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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Implementation Notes for GNU CLISP</title><link rel="stylesheet" type="text/css" href="impnotes.css" /><link rev="made" href="mailto:clisp-list@lists.sourceforge.net" /><meta name="generator" content="DocBook XSL Stylesheets V1.79.1" /><meta name="description" content="This document describes the GNU CLISP - an implementation of the ANSI CL standard. See for instructions on how to report bugs (both in the software and the documentaion). See for information on CLISP support." /><meta name="keywords" content="Lisp, Common Lisp, CLISP" /><meta name="date" content="'generated: 2017-10-27 14:57:00-04:00'" /><link rel="author" title="Authors" href="#authors" /><link rel="contents" title="Table of Contents" href="index.html" /><link rel="glossary" href="#glossary" /><link rel="help" href="#faq-help" title="How do I ask for help?" /><link rel="home" title="Home" href="http://clisp.org" /><link rel="index" href="idx.html" /></head><body><div class="book"><div class="titlepage"><div><div><h1 class="title"><a id="impnotes-top"></a>Implementation Notes for <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a></h1></div><div><h2 class="subtitle">These notes document <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> version 2.49.60+</h2></div><div><h3 class="corpauthor"><span class="inlinemediaobject"><img src="clisp.png" /></span></h3></div><div><div class="authorgroup"><a id="authors"></a><div class="author"><h3 class="author"><span class="firstname">Bruno</span> <span class="surname">Haible</span></h3><span class="contrib">The original author and long-time maintainer.</span> </div><div class="author"><h3 class="author"><span class="firstname">Michael</span> <span class="surname">Stoll</span></h3><span class="contrib">The original author.</span> </div><div class="author"><h3 class="author"><span class="firstname">Sam</span> <span class="surname">Steingold</span></h3><span class="contrib">Co-maintainer since 1998.</span> </div><div class="othercredit"><h3 class="othercredit"><span class="othername">Others</span></h3><span class="contrib">See
   <span class="emphasis"><em><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/COPYRIGHT"><code class="filename">COPYRIGHT</code></a></em></span>
   for the list of other contributors and the license.
 </span> </div></div></div><div><p class="copyright">Copyright © 1992-2010 Bruno Haible</p></div><div><p class="copyright">Copyright © 1998-2010 Sam Steingold</p></div><div><div class="legalnotice"><a id="legalese"></a><p class="legalnotice-title"><strong>Legal Status of the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
   Implementation Notes</strong></p><p>These notes are dually licensed under <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/copyleft/fdl.html" target="_top">FDL</a> and <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/copyleft/gpl.html" target="_top">GPL</a>.
   This means that you can redistribute this document under
   either of these two licenses, at your choice.</p><p><strong>These notes are covered by the <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/copyleft/fdl.html" target="_top">FDL</a>. </strong>Permission is granted to copy, distribute and/or modify this
    document under the terms of the GNU Free Documentation License
    (<a class="ulink" href="http://www.gnu.org/copyleft/fdl.html" target="_top">FDL</a>), either version 1.2 of the License, or (at your option) any
    later version published by the <a class="ulink" href="http://www.fsf.org" target="_top">Free Software Foundation (FSF)</a>;
    with no Invariant Sections,
    with no Front-Cover Text, and
    with no Back-Cover Texts.
    A copy of the license is included in <a class="xref" href="#fdl" title="Appendix B. GNU Free Documentation License">Appendix B, <em>GNU Free Documentation License</em></a>.
  </p><p><strong>These notes are covered by the <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/copyleft/gpl.html" target="_top">GPL</a>. </strong>This document documents free software; you can redistribute it
    and/or modify it under the terms of the GNU General Public License
    (<a class="ulink" href="http://www.gnu.org/copyleft/gpl.html" target="_top">GPL</a>), either version 2 of the License, or (at your option) any
    later version published by the <a class="ulink" href="http://www.fsf.org" target="_top">Free Software Foundation (FSF)</a>.
    A copy of the license is included in <a class="xref" href="#gpl" title="Appendix C. GNU General Public License">Appendix C, <em>GNU General Public License</em></a>.
  </p></div></div><div><div class="revhistory"><table style="border-style:solid; width:100%;" summary="Revision History"><tr><th align="left" valign="top" colspan="3"><strong>CLISP Release History</strong></th></tr><tr><td align="left">Release <span class="revnumber">1</span></td><td align="left"><span class="revdate">April 1987 - July 1992</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The project was
     started when both original authors, <span class="author"><span class="firstname">Bruno</span> <span class="surname">Haible</span></span> and <span class="author"><span class="firstname">Michael</span> <span class="surname">Stoll</span></span>, were
     students in Germany.</li><li class="listitem">The original version was for <a class="ulink" href="http://www.atari.org/" target="_top"><span class="platform">Atari</span></a> ST only,
     written in 68000 assembly language and <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a>.</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.0</span></td><td align="left"><span class="revdate">1992-10-09</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">the USENET newsgroup <a class="" href="https://groups.google.com/group/comp.os.linux">comp.os.linux</a>
 announcement (<a class="ulink" href="https://www.kernel.org/" target="_top"><span class="platform">Linux</span></a> binaries only)</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.1</span></td><td align="left"><span class="revdate">1993-01-01</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The first portable
     release, with source, released under <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/copyleft/gpl.html" target="_top">GPL</a>.</li><li class="listitem">Supported platforms: <a class="ulink" href="http://www.atari.org/" target="_top"><span class="platform">Atari</span></a> ST, <a class="ulink" href="http://www.amiga.org/" target="_top"><span class="platform">Amiga</span></a> 500-2000, <a class="ulink" href="http://www.freedos.org/" target="_top"><span class="platform">DOS</span></a>
     (emx, djgpp), <a class="ulink" href="http://www.os2.org/" target="_top"><span class="platform">OS/2</span></a> (emx), Unix (<a class="ulink" href="https://www.kernel.org/" target="_top"><span class="platform">Linux</span></a>, Sun4, Sun386, HP9000/800).
</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.1.1</span></td><td align="left"><span class="revdate">1993-01-11</span></td><td align="left">bruno</td></tr><tr><td align="left">Release <span class="revnumber">2.1.2</span></td><td align="left"><span class="revdate">1993-02-01</span></td><td align="left">bruno</td></tr><tr><td align="left">Release <span class="revnumber">2.1.3</span></td><td align="left"><span class="revdate">1993-02-03</span></td><td align="left">bruno</td></tr><tr><td align="left">Release <span class="revnumber">2.2</span></td><td align="left"><span class="revdate">1993-02-21</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Add test suite.
</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.2.1</span></td><td align="left"><span class="revdate">1993-03-04</span></td><td align="left">bruno</td></tr><tr><td align="left">Release <span class="revnumber">2.2.2</span></td><td align="left"><span class="revdate">1993-03-19</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="link" href="#ed" title="25.2.9. Function ED"><code class="varname">CUSTOM:*EDITOR*</code></a>
</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.3</span></td><td align="left"><span class="revdate">1993-03-30</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_load-time-value.html" target="_top"><code class="function">LOAD-TIME-VALUE</code></a></li><li class="listitem"><a class="link" href="#default-dir" title="20.3.5. Function EXT:DEFAULT-DIRECTORY"><code class="function">EXT:DEFAULT-DIRECTORY</code></a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.3.1</span></td><td align="left"><span class="revdate">1993-04-05</span></td><td align="left">bruno</td></tr><tr><td align="left">Release <span class="revnumber">2.4</span></td><td align="left"><span class="revdate">1993-05-24</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defpackage.html" target="_top"><code class="function">DEFPACKAGE</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_function-_a-expression.html" target="_top"><code class="function">FUNCTION-LAMBDA-EXPRESSION</code></a></li><li class="listitem"><a class="xref" href="#screen" title="32.1. Random Screen Access">Section 32.1, “Random Screen Access”</a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.5</span></td><td align="left"><span class="revdate">1993-06-29</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> function names.</li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_print-unr_dable-object.html" target="_top"><code class="function">PRINT-UNREADABLE-OBJECT</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_symbol-macrolet.html" target="_top"><code class="function">SYMBOL-MACROLET</code></a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.5.1</span></td><td align="left"><span class="revdate">1993-07-17</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">immutable objects</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.6</span></td><td align="left"><span class="revdate">1993-08-22</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Changed <a href="impnotes.html#bytecode" class="olink">bytecode</a> format</li><li class="listitem"><a class="link" href="#classes" title="4.2. Classes sec_4-3"><strong class="package"><span class="quote">“<span class="quote">CLOS</span>”</span></strong></a> package: <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_generic-function.html" target="_top"><code class="classname">GENERIC-FUNCTION</code></a>, <a class="link" href="#gen-flet"><code class="function">CLOS:GENERIC-FLET</code></a>, <a class="link" href="#gen-labels"><code class="function">CLOS:GENERIC-LABELS</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-slots.html" target="_top"><code class="function">WITH-SLOTS</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-accessors.html" target="_top"><code class="function">WITH-ACCESSORS</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_find-class.html" target="_top"><code class="function">FIND-CLASS</code></a>, (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_find-class.html" target="_top"><code class="function">FIND-CLASS</code></a>),
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_class-of.html" target="_top"><code class="function">CLASS-OF</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_class-name.html" target="_top"><code class="function">CLASS-NAME</code></a>, (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_class-name.html" target="_top"><code class="function">CLASS-NAME</code></a>), <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_slot-value.html" target="_top"><code class="function">SLOT-VALUE</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_slot-boundp.html" target="_top"><code class="function">SLOT-BOUNDP</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_slot-makunbound.html" target="_top"><code class="function">SLOT-MAKUNBOUND</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_slot-exists-p.html" target="_top"><code class="function">SLOT-EXISTS-P</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locfun_call-next-method.html" target="_top"><code class="function">CALL-NEXT-METHOD</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locfun_next-method-p.html" target="_top"><code class="function">NEXT-METHOD-P</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_no-_cable-method.html" target="_top"><code class="function">NO-APPLICABLE-METHOD</code></a>,
   <a class="link" href="#no-prim"><code class="function">CLOS:NO-PRIMARY-METHOD</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_no-next-method.html" target="_top"><code class="function">NO-NEXT-METHOD</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_find-method.html" target="_top"><code class="function">FIND-METHOD</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_add-method.html" target="_top"><code class="function">ADD-METHOD</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_remove-method.html" target="_top"><code class="function">REMOVE-METHOD</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_com_able-methods.html" target="_top"><code class="function">COMPUTE-APPLICABLE-METHODS</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_met_d-qualifiers.html" target="_top"><code class="function">METHOD-QUALIFIERS</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_fun_ion-keywords.html" target="_top"><code class="function">FUNCTION-KEYWORDS</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_slot-missing.html" target="_top"><code class="function">SLOT-MISSING</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_slot-unbound.html" target="_top"><code class="function">SLOT-UNBOUND</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_print-object.html" target="_top"><code class="function">PRINT-OBJECT</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_describe-object.html" target="_top"><code class="function">DESCRIBE-OBJECT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_sha_d-initialize.html" target="_top"><code class="function">SHARED-INITIALIZE</code></a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.6.1</span></td><td align="left"><span class="revdate">1993-09-01</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Changed <a href="impnotes.html#bytecode" class="olink">bytecode</a> format</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.7</span></td><td align="left"><span class="revdate">1993-09-27</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">top-level forms</li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_declaim.html" target="_top"><code class="function">DECLAIM</code></a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.8</span></td><td align="left"><span class="revdate">1993-11-08</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong></a>, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-2.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP-USER</span>”</span></strong></a></li><li class="listitem">New module: STDWIN</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.9</span></td><td align="left"><span class="revdate">1994-01-08</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Changed <a href="impnotes.html#bytecode" class="olink">bytecode</a> format</li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-condition.html" target="_top"><code class="function">DEFINE-CONDITION</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_ignore-errors.html" target="_top"><code class="function">IGNORE-ERRORS</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_handler-case.html" target="_top"><code class="function">HANDLER-CASE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_handler-bind.html" target="_top"><code class="function">HANDLER-BIND</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_restart-case.html" target="_top"><code class="function">RESTART-CASE</code></a>, <a class="link" href="#with-restarts" title="Macro EXT:WITH-RESTARTS"><code class="function">EXT:WITH-RESTARTS</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-simple-restart.html" target="_top"><code class="function">WITH-SIMPLE-RESTART</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_restart-bind.html" target="_top"><code class="function">RESTART-BIND</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-cond_ion-restarts.html" target="_top"><code class="function">WITH-CONDITION-RESTARTS</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_restart.html" target="_top"><code class="classname">RESTART</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_condition.html" target="_top"><code class="classname">CONDITION</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_serious-condition.html" target="_top"><code class="classname">SERIOUS-CONDITION</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_program-error.html" target="_top"><code class="classname">PROGRAM-ERROR</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_control-error.html" target="_top"><code class="classname">CONTROL-ERROR</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_arithmetic-error.html" target="_top"><code class="classname">ARITHMETIC-ERROR</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_division-by-zero.html" target="_top"><code class="classname">DIVISION-BY-ZERO</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_floati_int-overflow.html" target="_top"><code class="classname">FLOATING-POINT-OVERFLOW</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_floati_nt-underflow.html" target="_top"><code class="classname">FLOATING-POINT-UNDERFLOW</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_cell-error.html" target="_top"><code class="classname">CELL-ERROR</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_unbound-variable.html" target="_top"><code class="classname">UNBOUND-VARIABLE</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_undefined-function.html" target="_top"><code class="classname">UNDEFINED-FUNCTION</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_type-error.html" target="_top"><code class="classname">TYPE-ERROR</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_package-error.html" target="_top"><code class="classname">PACKAGE-ERROR</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_stream-error.html" target="_top"><code class="classname">STREAM-ERROR</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_end-of-file.html" target="_top"><code class="classname">END-OF-FILE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_file-error.html" target="_top"><code class="classname">FILE-ERROR</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_storage-condition.html" target="_top"><code class="classname">STORAGE-CONDITION</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_warning.html" target="_top"><code class="classname">WARNING</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_simple-condition.html" target="_top"><code class="classname">SIMPLE-CONDITION</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_simple-error.html" target="_top"><code class="classname">SIMPLE-ERROR</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_simple-type-error.html" target="_top"><code class="classname">SIMPLE-TYPE-ERROR</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_simple-warning.html" target="_top"><code class="classname">SIMPLE-WARNING</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-condition.html" target="_top"><code class="function">MAKE-CONDITION</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compute-restarts.html" target="_top"><code class="function">COMPUTE-RESTARTS</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_find-restart.html" target="_top"><code class="function">FIND-RESTART</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_invoke-restart.html" target="_top"><code class="function">INVOKE-RESTART</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_invoke-re_nteractively.html" target="_top"><code class="function">INVOKE-RESTART-INTERACTIVELY</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_abortcm_c_cm_use-value.html" target="_top"><code class="function">ABORT</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_abortcm_c_cm_use-value.html" target="_top"><code class="function">CONTINUE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_abortcm_c_cm_use-value.html" target="_top"><code class="function">MUFFLE-WARNING</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_abortcm_c_cm_use-value.html" target="_top"><code class="function">STORE-VALUE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_abortcm_c_cm_use-value.html" target="_top"><code class="function">USE-VALUE</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_invoke-debugger.html" target="_top"><code class="function">INVOKE-DEBUGGER</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_restart-name.html" target="_top"><code class="function">RESTART-NAME</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_arithmeti_or-operation.html" target="_top"><code class="function">ARITHMETIC-ERROR-OPERATION</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_arithmeti_or-operation.html" target="_top"><code class="function">ARITHMETIC-ERROR-OPERANDS</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_cell-error-name.html" target="_top"><code class="function">CELL-ERROR-NAME</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_type-erro_xpected-type.html" target="_top"><code class="function">TYPE-ERROR-DATUM</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_type-erro_xpected-type.html" target="_top"><code class="function">TYPE-ERROR-EXPECTED-TYPE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_package-error-package.html" target="_top"><code class="function">PACKAGE-ERROR-PACKAGE</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-error-stream.html" target="_top"><code class="function">STREAM-ERROR-STREAM</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_file-error-pathname.html" target="_top"><code class="function">FILE-ERROR-PATHNAME</code></a>,
   <code class="function">EXT:SIMPLE-CONDITION-FORMAT-STRING</code>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_simple-co_at-arguments.html" target="_top"><code class="function">SIMPLE-CONDITION-FORMAT-ARGUMENTS</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stbreak-on-signalsst.html" target="_top"><code class="varname">*BREAK-ON-SIGNALS*</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebugger-hookst.html" target="_top"><code class="varname">*DEBUGGER-HOOK*</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-readablyst.html" target="_top"><code class="varname">*PRINT-READABLY*</code></a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.10</span></td><td align="left"><span class="revdate">1994-06-22</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="link" href="#rd-ch-seq"><code class="function">EXT:READ-CHAR-SEQUENCE</code></a>, <a class="link" href="#wr-ch-seq"><code class="function">EXT:WRITE-CHAR-SEQUENCE</code></a>,
     <a class="link" href="#rd-by-seq"><code class="function">EXT:READ-BYTE-SEQUENCE</code></a>, <a class="link" href="#wr-by-seq"><code class="function">EXT:WRITE-BYTE-SEQUENCE</code></a></li><li class="listitem"><a class="xref" href="#gstream" title="31.6. Generic streams">Section 31.6, “Generic streams”</a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.11</span></td><td align="left"><span class="revdate">1994-07-04</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_loop.html" target="_top"><code class="function">LOOP</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locmac_loop-finish.html" target="_top"><code class="function">LOOP-FINISH</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_map-into.html" target="_top"><code class="function">MAP-INTO</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_d-long-float.html" target="_top"><code class="constant">LEAST-POSITIVE-NORMALIZED-SHORT-FLOAT</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_d-long-float.html" target="_top"><code class="constant">LEAST-NEGATIVE-NORMALIZED-SHORT-FLOAT</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_d-long-float.html" target="_top"><code class="constant">LEAST-POSITIVE-NORMALIZED-SINGLE-FLOAT</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_d-long-float.html" target="_top"><code class="constant">LEAST-NEGATIVE-NORMALIZED-SINGLE-FLOAT</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_d-long-float.html" target="_top"><code class="constant">LEAST-POSITIVE-NORMALIZED-DOUBLE-FLOAT</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_d-long-float.html" target="_top"><code class="constant">LEAST-NEGATIVE-NORMALIZED-DOUBLE-FLOAT</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_d-long-float.html" target="_top"><code class="constant">LEAST-POSITIVE-NORMALIZED-LONG-FLOAT</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_d-long-float.html" target="_top"><code class="constant">LEAST-NEGATIVE-NORMALIZED-LONG-FLOAT</code></a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.12</span></td><td align="left"><span class="revdate">1994-08-23</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">generational <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion</li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_destructuring-bind.html" target="_top"><code class="function">DESTRUCTURING-BIND</code></a></li><li class="listitem"><a class="link" href="#uncompile" title="25.2.2. Function EXT:UNCOMPILE"><code class="function">EXT:UNCOMPILE</code></a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.12.1</span></td><td align="left"><span class="revdate">1994-09-01</span></td><td align="left">bruno</td></tr><tr><td align="left">Release <span class="revnumber">2.13</span></td><td align="left"><span class="revdate">1994-10-26</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Changed <a href="impnotes.html#bytecode" class="olink">bytecode</a> format</li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_wild-pathname-p.html" target="_top"><code class="function">WILD-PATHNAME-P</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_pathname-match-p.html" target="_top"><code class="function">PATHNAME-MATCH-P</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_translate-pathname.html" target="_top"><code class="function">TRANSLATE-PATHNAME</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_logical-pathname.html" target="_top"><code class="function">LOGICAL-PATHNAME</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_logical-p_translations.html" target="_top"><code class="function">LOGICAL-PATHNAME-TRANSLATIONS</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_translate_cal-pathname.html" target="_top"><code class="function">TRANSLATE-LOGICAL-PATHNAME</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_load-logi_translations.html" target="_top"><code class="function">LOAD-LOGICAL-PATHNAME-TRANSLATIONS</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile-file-pathname.html" target="_top"><code class="function">COMPILE-FILE-PATHNAME</code></a>
</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.13.1</span></td><td align="left"><span class="revdate">1995-01-01</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Changed <a href="impnotes.html#bytecode" class="olink">bytecode</a> format</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.14</span></td><td align="left"><span class="revdate">1995-04-04</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_row-major-aref.html" target="_top"><code class="function">ROW-MAJOR-AREF</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_delete-package.html" target="_top"><code class="function">DELETE-PACKAGE</code></a>,
     <a class="link" href="#muffle-cerrors" title="Macro EXT:MUFFLE-CERRORS"><code class="function">EXT:MUFFLE-CERRORS</code></a>, <a href="impnotes.html#appease-cerrors" class="olink"><code class="function">EXT:APPEASE-CERRORS</code></a>, <a href="impnotes.html#exit-on-error" class="olink"><code class="function">EXT:EXIT-ON-ERROR</code></a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.15</span></td><td align="left"><span class="revdate">1995-04-25</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">New modules: <code class="filename">wildcard</code>,
     <span class="module"><a class="filename" href="#regexp-mod" title="33.4. POSIX Regular Expressions"><code class="filename">regexp</code></a></span></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_formatter.html" target="_top"><code class="function">FORMATTER</code></a>, <a class="link" href="#final" title="31.8. Finalization"><code class="function">EXT:FINALIZE</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_file-stream.html" target="_top"><code class="classname">FILE-STREAM</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_synonym-stream.html" target="_top"><code class="classname">SYNONYM-STREAM</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_broadcast-stream.html" target="_top"><code class="classname">BROADCAST-STREAM</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_concatenated-stream.html" target="_top"><code class="classname">CONCATENATED-STREAM</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_two-way-stream.html" target="_top"><code class="classname">TWO-WAY-STREAM</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_echo-stream.html" target="_top"><code class="classname">ECHO-STREAM</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string-stream.html" target="_top"><code class="classname">STRING-STREAM</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_open-stream-p.html" target="_top"><code class="function">OPEN-STREAM-P</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_synonym-stream-symbol.html" target="_top"><code class="function">SYNONYM-STREAM-SYMBOL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_broadcast_ream-streams.html" target="_top"><code class="function">BROADCAST-STREAM-STREAMS</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_concatena_ream-streams.html" target="_top"><code class="function">CONCATENATED-STREAM-STREAMS</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_two-way-s_utput-stream.html" target="_top"><code class="function">TWO-WAY-STREAM-INPUT-STREAM</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_two-way-s_utput-stream.html" target="_top"><code class="function">TWO-WAY-STREAM-OUTPUT-STREAM</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_echo-stre_utput-stream.html" target="_top"><code class="function">ECHO-STREAM-INPUT-STREAM</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_echo-stre_utput-stream.html" target="_top"><code class="function">ECHO-STREAM-OUTPUT-STREAM</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_print-not-readable.html" target="_top"><code class="classname">PRINT-NOT-READABLE</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_print-not_dable-object.html" target="_top"><code class="function">PRINT-NOT-READABLE-OBJECT</code></a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.16</span></td><td align="left"><span class="revdate">1995-06-23</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Changed <a href="impnotes.html#bytecode" class="olink">bytecode</a> format</li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_complement.html" target="_top"><code class="function">COMPLEMENT</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-stan_rd-io-syntax.html" target="_top"><code class="function">WITH-STANDARD-IO-SYNTAX</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_dynamic-extent.html" target="_top"><code class="literal">DYNAMIC-EXTENT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_lambda.html" target="_top"><code class="function">LAMBDA</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_ignorecm_ignorable.html" target="_top"><code class="literal">IGNORABLE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_constantly.html" target="_top"><code class="function">CONSTANTLY</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-hash_ble-iterator.html" target="_top"><code class="function">WITH-HASH-TABLE-ITERATOR</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_hash-table-rehash-size.html" target="_top"><code class="function">HASH-TABLE-REHASH-SIZE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_hash-tabl_sh-threshold.html" target="_top"><code class="function">HASH-TABLE-REHASH-THRESHOLD</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_hash-table-size.html" target="_top"><code class="function">HASH-TABLE-SIZE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_hash-table-test.html" target="_top"><code class="function">HASH-TABLE-TEST</code></a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.17</span></td><td align="left"><span class="revdate">1996-07-21</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Changed <a href="impnotes.html#bytecode" class="olink">bytecode</a> format</li><li class="listitem"><a class="link" href="#sose"><code class="function">SOCKET:SOCKET-SERVER</code></a>, <a class="link" href="#sose-close"><code class="function">SOCKET:SOCKET-SERVER-CLOSE</code></a>, <a class="link" href="#sose-hopo"><code class="function">SOCKET:SOCKET-SERVER-PORT</code></a>, <a class="link" href="#so-wait"><code class="function">SOCKET:SOCKET-WAIT</code></a>,
    <a class="link" href="#so-accept"><code class="function">SOCKET:SOCKET-ACCEPT</code></a>, <a class="link" href="#so-connect"><code class="function">SOCKET:SOCKET-CONNECT</code></a>, <a class="link" href="#sost-hopo"><code class="function">SOCKET:SOCKET-STREAM-HOST</code></a>, <a class="link" href="#sost-hopo"><code class="function">SOCKET:SOCKET-STREAM-PORT</code></a>,
    <code class="function">SOCKET:SOCKET-SERVICE-PORT</code>, <a class="link" href="#sost-peer"><code class="function">SOCKET:SOCKET-STREAM-PEER</code></a>
</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.18</span></td><td align="left"><span class="revdate">1997-05-03</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="link" href="#deflang"><code class="function">I18N:DEFLANGUAGE</code></a>, <a class="link" href="#def-i-l"><code class="function">I18N:DEFINTERNATIONAL</code></a>, <a class="link" href="#defloc"><code class="function">I18N:DEFLOCALIZED</code></a></li><li class="listitem"><a href="impnotes.html#load-comp" class="olink"><code class="varname">CUSTOM:*LOAD-COMPILING*</code></a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.19</span></td><td align="left"><span class="revdate">1997-08-07</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="ulink" href="http://www.cliki.net/CLX" target="_top"><span class="command"><strong>CLX</strong></span></a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.20</span></td><td align="left"><span class="revdate">1997-09-25</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stread-evalst.html" target="_top"><code class="varname">*READ-EVAL*</code></a></li><li class="listitem"><a class="link" href="#time" title="25.2.8. Macro TIME"><code class="function">EXT:TIMES</code></a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.20.1</span></td><td align="left"><span class="revdate">1997-12-06</span></td><td align="left">bruno</td></tr><tr><td align="left">Release <span class="revnumber">2.21</span></td><td align="left"><span class="revdate">1998-09-09</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Changed <a href="impnotes.html#bytecode" class="olink">bytecode</a> format</li><li class="listitem">Removed module STDWIN.</li><li class="listitem"><a class="link" href="#warn-fpc" title="Variable CUSTOM:*WARN-ON-FLOATING-POINT-CONTAGION*"><code class="varname">CUSTOM:*WARN-ON-FLOATING-POINT-CONTAGION*</code></a>, <a class="link" href="#flocont" title="12.2.4.1. Rule of Float Precision Contagion sec_12-1-4-4"><code class="varname">CUSTOM:*FLOATING-POINT-CONTAGION-ANSI*</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_floati_oint-inexact.html" target="_top"><code class="classname">FLOATING-POINT-INEXACT</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_floati_id-operation.html" target="_top"><code class="classname">FLOATING-POINT-INVALID-OPERATION</code></a></li><li class="listitem"><a class="link" href="#probe-dir" title="20.3.1. Function EXT:PROBE-DIRECTORY"><code class="function">EXT:PROBE-DIRECTORY</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_ensure-di_tories-exist.html" target="_top"><code class="function">ENSURE-DIRECTORIES-EXIST</code></a></li><li class="listitem"> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-right-marginst.html" target="_top"><code class="varname">*PRINT-RIGHT-MARGIN*</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_array-displacement.html" target="_top"><code class="function">ARRAY-DISPLACEMENT</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_boolean.html" target="_top"><code class="classname">BOOLEAN</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_copy-structure.html" target="_top"><code class="function">COPY-STRUCTURE</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_generic-function.html" target="_top"><code class="classname">GENERIC-FUNCTION</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_structure-object.html" target="_top"><code class="classname">STRUCTURE-OBJECT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_special-operator-p.html" target="_top"><code class="function">SPECIAL-OPERATOR-P</code></a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.22</span></td><td align="left"><span class="revdate">1999-01-08</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Changed <a href="impnotes.html#bytecode" class="olink">bytecode</a> format</li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_base-char.html" target="_top"><code class="classname">BASE-CHAR</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_extended-char.html" target="_top"><code class="classname">EXTENDED-CHAR</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_base-string.html" target="_top"><code class="classname">BASE-STRING</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-base-string.html" target="_top"><code class="classname">SIMPLE-BASE-STRING</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_get-setf-expansion.html" target="_top"><code class="function">GET-SETF-EXPANSION</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-setf-expander.html" target="_top"><code class="function">DEFINE-SETF-EXPANDER</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_parse-error.html" target="_top"><code class="classname">PARSE-ERROR</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_reader-error.html" target="_top"><code class="classname">READER-ERROR</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_unbound-slot-instance.html" target="_top"><code class="function">UNBOUND-SLOT-INSTANCE</code></a></li><li class="listitem"><a class="link" href="#sost-local"><code class="function">SOCKET:SOCKET-STREAM-LOCAL</code></a>, <a class="link" href="#sose-hopo"><code class="function">SOCKET:SOCKET-SERVER-HOST</code></a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.23</span></td><td align="left"><span class="revdate">1999-07-22</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">New module:
     <span class="module"><a class="filename" href="#postgresql" title="33.9. PostgreSQL Database Access"><code class="filename">postgresql</code></a></span></li><li class="listitem"><a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a>, <a class="link" href="#encoding" title="31.5. Encodings"><strong class="package"><span class="quote">“<span class="quote">CHARSET</span>”</span></strong></a>, <a href="impnotes.html#def-file-enc" class="olink"><code class="varname">CUSTOM:*DEFAULT-FILE-ENCODING*</code></a>, <a href="impnotes.html#path-enc" class="olink"><code class="varname">CUSTOM:*PATHNAME-ENCODING*</code></a>,
     <a href="impnotes.html#term-enc" class="olink"><code class="varname">CUSTOM:*TERMINAL-ENCODING*</code></a>, <a href="impnotes.html#misc-enc" class="olink"><code class="varname">CUSTOM:*MISC-ENCODING*</code></a> <a href="impnotes.html#foreign-enc" class="olink"><code class="varname">CUSTOM:*FOREIGN-ENCODING*</code></a>,
     <code class="varname">AFFI:*FOREIGN-ENCODING*</code></li><li class="listitem"><a class="xref" href="#gray" title="Chapter 30. Gray streams">Chapter 30, <em>Gray streams</em></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-external-format.html" target="_top"><code class="function">STREAM-EXTERNAL-FORMAT</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-package-iterator.html" target="_top"><code class="function">WITH-PACKAGE-ITERATOR</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_all_ate-instance.html" target="_top"><code class="function">ALLOCATE-INSTANCE</code></a></li><li class="listitem"><a class="xref" href="#weak-pointer" title="31.7.1. Weak Pointers">Section 31.7.1, “Weak Pointers”</a></li><li class="listitem"><a class="link" href="#bin-input" title="21.3.1. Binary input, READ-BYTE, EXT:READ-INTEGER &amp; EXT:READ-FLOAT"><code class="function">EXT:READ-INTEGER</code></a>, <a class="link" href="#bin-output" title="21.3.2. Binary output, WRITE-BYTE, EXT:WRITE-INTEGER &amp; EXT:WRITE-FLOAT"><code class="function">EXT:WRITE-INTEGER</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_simple-co_at-arguments.html" target="_top"><code class="function">SIMPLE-CONDITION-FORMAT-CONTROL</code></a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.24</span></td><td align="left"><span class="revdate">2000-03-06</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="link" href="#bin-input" title="21.3.1. Binary input, READ-BYTE, EXT:READ-INTEGER &amp; EXT:READ-FLOAT"><code class="function">EXT:READ-FLOAT</code></a>,
     <a class="link" href="#bin-output" title="21.3.2. Binary output, WRITE-BYTE, EXT:WRITE-INTEGER &amp; EXT:WRITE-FLOAT"><code class="function">EXT:WRITE-FLOAT</code></a></li><li class="listitem"><a class="link" href="#char-width" title="13.1.3. Function EXT:CHAR-WIDTH"><code class="function">EXT:CHAR-WIDTH</code></a>, <a class="link" href="#string-width" title="16.1.2. Function EXT:STRING-WIDTH"><code class="function">EXT:STRING-WIDTH</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-compilation-unit.html" target="_top"><code class="function">WITH-COMPILATION-UNIT</code></a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.25</span></td><td align="left"><span class="revdate">2001-03-15</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Changed <a href="impnotes.html#bytecode" class="olink">bytecode</a> format</li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_inspect.html" target="_top"><code class="function">INSPECT</code></a>,
    <code class="function">EXT:CLHS</code></li><li class="listitem"><a class="link" href="#string-byte" title="31.5.7. Converting between strings and byte vectors"><code class="function">EXT:CONVERT-STRING-FROM-BYTES</code></a>,
     <a class="link" href="#string-byte" title="31.5.7. Converting between strings and byte vectors"><code class="function">EXT:CONVERT-STRING-TO-BYTES</code></a></li><li class="listitem"><a class="link" href="#rbla"><code class="function">EXT:READ-BYTE-LOOKAHEAD</code></a>, <a class="link" href="#st-rbla"><code class="function">GRAY:STREAM-READ-BYTE-LOOKAHEAD</code></a>, <a class="link" href="#rbwhp"><code class="function">EXT:READ-BYTE-WILL-HANG-P</code></a>, <a class="link" href="#rbwhp"><code class="function">GRAY:STREAM-READ-BYTE-WILL-HANG-P</code></a>, <a class="link" href="#rbnh"><code class="function">EXT:READ-BYTE-NO-HANG</code></a>,
     <a class="link" href="#rbnh"><code class="function">GRAY:STREAM-READ-BYTE-NO-HANG</code></a></li><li class="listitem"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> improvements (UNC pathnames, registry,
     screen)</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.25.1</span></td><td align="left"><span class="revdate">2001-04-06</span></td><td align="left">sds</td></tr><tr><td align="left">Release <span class="revnumber">2.26</span></td><td align="left"><span class="revdate">2001-05-23</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Changed <a href="impnotes.html#bytecode" class="olink">bytecode</a> format</li><li class="listitem">dropped CLtL1,
     added <code class="constant">:LISP=CL</code> to <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-compiler-macro.html" target="_top"><code class="function">DEFINE-COMPILER-MACRO</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_upgraded-_ex-part-type.html" target="_top"><code class="function">UPGRADED-COMPLEX-PART-TYPE</code></a></li><li class="listitem"><a class="link" href="#run-prog"><code class="function">EXT:RUN-SHELL-COMMAND</code></a>, <a class="link" href="#run-prog"><code class="function">EXT:RUN-PROGRAM</code></a> accept <code class="constant">:WAIT</code></li><li class="listitem">compiler checks function call signatures
</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.27</span></td><td align="left"><span class="revdate">2001-07-17</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="link" href="#getenv" title="32.8. Operating System Environment"><code class="function">EXT:GETENV</code></a>)</code></li><li class="listitem"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/install.bat"><code class="filename">src/install.bat</code></a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.28</span></td><td align="left"><span class="revdate">2002-03-03</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Changed <a href="impnotes.html#bytecode" class="olink">bytecode</a> format</li><li class="listitem">[<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] Pretty-Printer</li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-load-form.html" target="_top"><code class="function">MAKE-LOAD-FORM</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-load_saving-slots.html" target="_top"><code class="function">MAKE-LOAD-FORM-SAVING-SLOTS</code></a></li><li class="listitem"><a class="xref" href="#weak-ht" title="31.7.9. Weak Hash Tables">Section 31.7.9, “Weak Hash Tables”</a></li><li class="listitem"><a class="link" href="#fcase" title="5.6. Macro EXT:FCASE"><code class="function">EXT:FCASE</code></a></li><li class="listitem"><a class="link" href="#gettext"><code class="function">I18N:GETTEXT</code></a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.29</span></td><td align="left"><span class="revdate">2002-07-25</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Bug-fix/portability:
   <a class="ulink" href="http://gcc.gnu.org/" target="_top"><span class="command"><strong>gcc</strong></span></a> 3.1 etc</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.30</span></td><td align="left"><span class="revdate">2002-09-15</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Do not bundle
    <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>, <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/gettext/" target="_top">gettext</a>, <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://tiswww.case.edu/php/chet/readline/readline.html" target="_top">readline</a>, <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://libsigsegv.sourceforge.net/" target="_top">libsigsegv</a>.</li><li class="listitem"><a class="link" href="#charset-UCS-4"><code class="constant">CHARSET:UCS-4</code></a></li><li class="listitem"><a class="link" href="#name-type-split" title="Name/type namestring split"><code class="varname">CUSTOM:*PARSE-NAMESTRING-DOT-FILE*</code></a></li><li class="listitem"><a class="link" href="#sost-shut"><code class="function">SOCKET:SOCKET-STREAM-SHUTDOWN</code></a></li><li class="listitem"><a class="link" href="#stream-lock"><code class="function">POSIX:STREAM-LOCK</code></a>, <a class="link" href="#copy-file"><code class="function">POSIX:COPY-FILE</code></a>,
     <a class="link" href="#dup-handle"><code class="function">POSIX:DUPLICATE-HANDLE</code></a></li><li class="listitem">New module: <span class="module"><a class="filename" href="#oracle" title="33.10. Oracle Interface"><code class="filename">oracle</code></a></span></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.31</span></td><td align="left"><span class="revdate">2003-09-01</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Changed <a href="impnotes.html#bytecode" class="olink">bytecode</a> format</li><li class="listitem">New modules:
     <span class="module"><a class="filename" href="#fastcgi" title="33.18. The FastCGI Interface"><code class="filename">fastcgi</code></a></span>, <span class="module"><a class="filename" href="#dir-key" title="33.8. Directory Access"><code class="filename">dirkey</code></a></span>, <span class="module"><a href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/bindings/win32/"><code class="filename">bindings/win32</code></a></span>,
     <span class="module"><a class="filename" href="#syscalls" title="33.2. System Calls"><code class="filename">syscalls</code></a></span>, <span class="module"><a class="filename" href="#netica" title="33.14. Netica Interface"><code class="filename">netica</code></a></span></li><li class="listitem">Support modules on <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>.</li><li class="listitem"><a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> 3.2</li><li class="listitem">New backquote implementation.</li><li class="listitem">Many [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] compliance fixes.</li><li class="listitem">More <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> functionality.</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.32</span></td><td align="left"><span class="revdate">2003-12-29</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">support
     <a class="ulink" href="http://www.unix.org/version2/whatsnew/lfs.html" target="_top"><span class="platform">LFS</span></a></li><li class="listitem">New modules: <span class="module"><a class="filename" href="#berkeley-db" title="33.7. Berkeley DB access"><code class="filename">berkeley-db</code></a></span>,
     <span class="module"><a class="filename" href="#pcre" title="33.15. Perl Compatible Regular Expressions"><code class="filename">pcre</code></a></span></li></ul></div>
</td></tr><tr><td align="left">Release <span class="revnumber">2.33</span></td><td align="left"><span class="revdate">2004-03-17</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Changed <a href="impnotes.html#bytecode" class="olink">bytecode</a> format</li><li class="listitem"><a class="link" href="#mod-expt" title="Function EXT:MOD-EXPT"><code class="function">EXT:MOD-EXPT</code></a>,
     <a class="link" href="#apropos" title="25.2.10. Functions APROPOS &amp; APROPOS-LIST"><code class="varname">CUSTOM:*APROPOS-MATCHER*</code></a>, <a class="link" href="#argv" title="25.3.5. Function EXT:ARGV"><code class="function">EXT:ARGV</code></a>, <a class="link" href="#st-position"><code class="function">GRAY:STREAM-POSITION</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-me_-combination.html" target="_top"><code class="function">DEFINE-METHOD-COMBINATION</code></a></li><li class="listitem">Portability: removed <a class="ulink" href="https://en.wikipedia.org/wiki/Acorn_Computers" target="_top"><span class="platform">Acorn</span></a> and <a class="ulink" href="http://www.amiga.org/" target="_top"><span class="platform">Amiga</span></a> support,
     fixed UNIXes.</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.33.1</span></td><td align="left"><span class="revdate">2004-05-22</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Bug-fixes, portability:
     <a class="ulink" href="http://gcc.gnu.org/" target="_top"><span class="command"><strong>gcc</strong></span></a> 3.4</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.33.2</span></td><td align="left"><span class="revdate">2004-06-02</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Portability: RedHat Fedora
     <a class="ulink" href="https://www.kernel.org/" target="_top"><span class="platform">Linux</span></a>/x86</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.34</span></td><td align="left"><span class="revdate">2005-07-20</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Changed <a href="impnotes.html#bytecode" class="olink">bytecode</a> format</li><li class="listitem"><a class="xref" href="#mop-chap" title="Chapter 29. Meta-Object Protocol">Chapter 29, <em>Meta-Object Protocol</em></a></li><li class="listitem"><a class="xref" href="#weak" title="31.7. Weak Objects">Section 31.7, “Weak Objects”</a></li><li class="listitem"><a class="xref" href="#package-case" title="11.5. Package Case-Sensitivity">Section 11.5, “Package Case-Sensitivity”</a></li><li class="listitem"><a href="impnotes.html#global-handler" class="olink"><code class="function">EXT:SET-GLOBAL-HANDLER</code></a>,
     <a href="impnotes.html#without-global-handlers" class="olink"><code class="function">EXT:WITHOUT-GLOBAL-HANDLERS</code></a></li><li class="listitem">Portability: removed <a class="ulink" href="http://www.freedos.org/" target="_top"><span class="platform">DOS</span></a> and <a class="ulink" href="http://www.os2.org/" target="_top"><span class="platform">OS/2</span></a>
     support.</li><li class="listitem">New modules: <span class="module"><a class="filename" href="#matlab" title="33.13. Matlab Interface"><code class="filename">matlab</code></a></span>, <span class="module"><a class="filename" href="#rawsock" title="33.17. Raw Socket Access"><code class="filename">rawsock</code></a></span>, <span class="module"><a class="filename" href="#zlib" title="33.16. Interface to zlib"><code class="filename">zlib</code></a></span>,
     <span class="module"><a class="filename" href="#i18n-mod" title="33.3. Internationalization of User Programs"><code class="filename">i18n</code></a></span>, <span class="module"><a class="filename" href="#pari" title="33.12. Computer Algebra System PARI"><code class="filename">pari</code></a></span>.</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.35</span></td><td align="left"><span class="revdate">2005-08-29</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="link" href="#compiled-file-p" title="24.7. Function EXT:COMPILED-FILE-P [CLRFI-2]"><code class="function">EXT:COMPILED-FILE-P</code></a></li><li class="listitem"><a class="link" href="#char-invertcase" title="13.7.1. Function EXT:CHAR-INVERTCASE"><code class="function">EXT:CHAR-INVERTCASE</code></a>, <a class="link" href="#string-invertcase" title="16.1.3. Functions EXT:STRING-INVERTCASE and EXT:NSTRING-INVERTCASE"><code class="function">EXT:STRING-INVERTCASE</code></a>,
     <a class="link" href="#string-invertcase" title="16.1.3. Functions EXT:STRING-INVERTCASE and EXT:NSTRING-INVERTCASE"><code class="function">EXT:NSTRING-INVERTCASE</code></a></li><li class="listitem"><a class="link" href="#fcntl"><code class="function">POSIX:STREAM-OPTIONS</code></a></li><li class="listitem">Close all <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a>s before
     <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/exec.html"><code class="function">exec</code></a>.</li></ul></div>
</td></tr><tr><td align="left">Release <span class="revnumber">2.36</span></td><td align="left"><span class="revdate">2005-12-04</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="link" href="#open-http" title="31.11.9. Function EXT:OPEN-HTTP and macro EXT:WITH-HTTP-INPUT"><code class="function">EXT:OPEN-HTTP</code></a>, <a class="link" href="#notspec-decl" title="Declaration EXT:NOTSPECIAL"><code class="literal">EXT:NOTSPECIAL</code></a>,
     <a class="link" href="#def-c-const"><code class="function">FFI:DEF-C-CONST</code></a>, <a class="link" href="#base64"><code class="constant">BASE64</code></a>
   </li><li class="listitem"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/clx/new-clx/demos/koch.lisp"><code class="filename">modules/clx/new-clx/demos/koch.lisp</code></a></li><li class="listitem"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/spvw_sigterm.d"><code class="filename">src/spvw_sigterm.d</code></a></li></ul></div>
</td></tr><tr><td align="left">Release <span class="revnumber">2.37</span></td><td align="left"><span class="revdate">2006-01-02</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="link" href="#sose"><code class="function">SOCKET:SOCKET-SERVER</code></a> accepts
     <code class="constant">:INTERFACE</code> and <code class="constant">:BACKLOG</code>.
   </li><li class="listitem">Fixed <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="link" href="#getenv" title="32.8. Operating System Environment"><code class="function">EXT:GETENV</code></a>)</code>.
</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.38</span></td><td align="left"><span class="revdate">2006-01-24</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a href="impnotes.html#image" class="olink"><code class="function">EXT:SAVEINITMEM</code></a> creates standalone
   executables.</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.39</span></td><td align="left"><span class="revdate">2006-07-16</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Reliable stack
     overflow detection and recovery.</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.40</span></td><td align="left"><span class="revdate">2006-09-23</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Changed <a href="impnotes.html#bytecode" class="olink">bytecode</a> format</li><li class="listitem">Keep doc string and <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> in the closure object.
</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.41</span></td><td align="left"><span class="revdate">2006-10-13</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="link" href="#dffi-default-lib"><code class="function">FFI:DEFAULT-FOREIGN-LIBRARY</code></a></li><li class="listitem">New module: <span class="module"><a class="filename" href="#libsvm" title="33.11. LibSVM Interface"><code class="filename">libsvm</code></a></span></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.42</span></td><td align="left"><span class="revdate">2007-10-16</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="xref" href="#defstruct-mop" title="8.2. The structure Meta-Object Protocol">Section 8.2, “The structure Meta-Object Protocol”</a></li><li class="listitem"><a class="link" href="#rename-dir" title="20.3.8. Function EXT:RENAME-DIRECTORY"><code class="function">EXT:RENAME-DIRECTORY</code></a></li><li class="listitem">Many additions to
     <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/clx/new-clx/demos/"><code class="filename">modules/clx/new-clx/demos/</code></a>
   </li><li class="listitem">New modules: <span class="module"><a class="filename" href="#gtk" title="33.20. GTK Interface"><code class="filename">gtk2</code></a></span>, <span class="module"><a class="filename" href="#gdbm" title="33.6. GDBM - The GNU database manager"><code class="filename">gdbm</code></a></span></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.43</span></td><td align="left"><span class="revdate">2007-11-18</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> build process is now in compliance
     with the GNU standards.</li><li class="listitem">Use <span class="command"><strong>gnulib-tool</strong></span> to sync
     with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/gnulib/" target="_top">Portability Library</a>.</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.43.1</span></td><td align="left"><span class="revdate">2008-02-24</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Portability: work around
     <a class="ulink" href="http://gcc.gnu.org/" target="_top"><span class="command"><strong>gcc</strong></span></a> <a class="ulink" href="http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34300" target="_top">bug
      34300</a> present in <a class="ulink" href="http://gcc.gnu.org/" target="_top"><span class="command"><strong>gcc</strong></span></a> 4.2 and 4.3.</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.44</span></td><td align="left"><span class="revdate">2008-02-02</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Do not bundle <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libffcall/" target="_top">libffcall</a>.
</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.44.1</span></td><td align="left"><span class="revdate">2008-02-24</span></td><td align="left">bruno</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Portability: work around
     <a class="ulink" href="http://gcc.gnu.org/" target="_top"><span class="command"><strong>gcc</strong></span></a> <a class="ulink" href="http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34300" target="_top">bug
      34300</a> present in <a class="ulink" href="http://gcc.gnu.org/" target="_top"><span class="command"><strong>gcc</strong></span></a> 4.2 and 4.3.</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.45</span></td><td align="left"><span class="revdate">2008-05-15</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Changed <a href="impnotes.html#bytecode" class="olink">bytecode</a> format</li><li class="listitem">Just-In-Time compilation (<span class="strong"><strong><a class="ulink" href="http://www.cygwin.com/acronyms/#PTC" target="_top">experimental</a></strong></span>)
     via <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/lightning/" target="_top">lightning</a>.</li><li class="listitem"><a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> and <a class="link" href="#def-c-var"><code class="function">FFI:DEF-C-VAR</code></a> accept <code class="constant">:VERSION</code>.
   </li><li class="listitem"><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-1.html">read-eval-print loop</a> commands accept arguments.</li><li class="listitem"><a class="xref" href="#stdio" title="33.2.14. Standard file input and output">Section 33.2.14, “Standard file input and output”</a>.</li><li class="listitem">Fixed cross-compilation.</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.46</span></td><td align="left"><span class="revdate">2008-07-02</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><code class="constant">:WORD-SIZE=64</code> in
     <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a> on 64-bit platforms.</li><li class="listitem"><a class="xref" href="#errno" title="33.2.15. Error handling">Section 33.2.15, “Error handling”</a>.</li><li class="listitem">Macro <code class="function">XLIB:WITH-OPEN-DISPLAY</code>.
   </li><li class="listitem">Fixed the remaining bugs in
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_special.html" target="_top"><code class="literal">SPECIAL</code></a> bindings in evaluated code on <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="strong"><strong><code class="option">TYPECODES</code></strong></span></a> platforms.
</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.47</span></td><td align="left"><span class="revdate">2008-10-23</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">New module: <span class="module"><a class="filename" href="#dbus" title="33.19. Interface to D-Bus"><code class="filename">dbus</code></a></span></li><li class="listitem"><a class="link" href="#probe-path" title="20.1.1. Function EXT:PROBE-PATHNAME"><code class="function">EXT:PROBE-PATHNAME</code></a></li><li class="listitem"><a class="link" href="#canonicalize" title="31.11.13. Function EXT:CANONICALIZE"><code class="function">EXT:CANONICALIZE</code></a></li><li class="listitem"><a class="link" href="#reopen" title="Variable CUSTOM:*REOPEN-OPEN-FILE*"><code class="varname">CUSTOM:*REOPEN-OPEN-FILE*</code></a></li><li class="listitem"><a class="link" href="#file-size"><code class="function">POSIX:FILE-SIZE</code></a></li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.48</span></td><td align="left"><span class="revdate">2009-07-28</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Thread support
   (<span class="strong"><strong><a class="ulink" href="http://www.cygwin.com/acronyms/#PTC" target="_top">experimental</a></strong></span>), see <a class="xref" href="#mt" title="32.5. Multiple Threads of Execution">Section 32.5, “Multiple Threads of Execution”</a></li><li class="listitem"><a class="link" href="#wait"><code class="function">POSIX:WAIT</code></a>
   </li><li class="listitem">
     <a class="link" href="#trim-if" title="17.1.1. Function EXT:TRIM-IF"><code class="function">EXT:TRIM-IF</code></a>
   </li><li class="listitem">
     <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/m4/clisp.m4"><code class="filename">src/m4/clisp.m4</code></a>
</li></ul></div></td></tr><tr><td align="left">Release <span class="revnumber">2.49</span></td><td align="left"><span class="revdate">2010-07-07</span></td><td align="left">sds</td></tr><tr><td align="left" colspan="3"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a href="clisp-link.html#opt-install" class="olink"><code class="varname">CUSTOM:*USER-LIB-DIRECTORY*</code></a>; <a class="link" href="#mod-dynload" title="32.2.5. Dynamic module loading">dynamic
    modules</a> are now the default build option</li><li class="listitem"><code class="option"><a href="clisp.html#opt-norl" class="olink">-disable-readline</a></code></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss065.html" target="_top">COMPILER-DIAGNOSTICS:USE-HANDLER</a></li><li class="listitem">Updated <span class="module"><a class="filename" href="#pari" title="33.12. Computer Algebra System PARI"><code class="filename">pari</code></a></span></li></ul></div></td></tr></table></div></div><div><div class="abstract"><a id="clisp-abstract"></a><p class="title"><strong>Abstract</strong></p><p>This document describes the
   <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> - an implementation of the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>].</p><p>See <a href="clisp.html#bugs" class="olink">the section called “Bugs”</a> for instructions
    on how to report bugs (both in the software and the documentaion).</p><p>See <a href="impnotes.html#faq-help" class="olink">Q: A.1.1.5</a> for
    information on <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> support.</p></div></div></div><hr /></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="preface"><a href="#overview">Overview</a></span></dt><dt><span class="preface"><a href="#conventions">Conventions</a></span></dt><dt><span class="part"><a href="#clhs-chapters">I. Chapters or the Common Lisp HyperSpec</a></span></dt><dd><dl><dt><span class="chapter"><a href="#intro">1. Introduction   chap-1</a></span></dt><dd><dl><dt><span class="section"><a href="#spec-symb">1.1. Special Symbols   sec_1-4-1-3</a></span></dt><dt><span class="section"><a href="#error-terms">1.2. Error Terminology   sec_1-4-2</a></span></dt><dt><span class="section"><a href="#cl-symb">1.3. Symbols in the Package <strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong>   sec_1-9</a></span></dt></dl></dd><dt><span class="chapter"><a href="#syntax">2. Syntax chap-2</a></span></dt><dd><dl><dt><span class="section"><a href="#std-char">2.1. Standard Characters   sec_2-1-3</a></span></dt><dt><span class="section"><a href="#reader-alg">2.2. Reader Algorithm   sec_2-2</a></span></dt><dt><span class="section"><a href="#tokens">2.3. Symbols as Tokens   sec_2-3-4</a></span></dt><dt><span class="section"><a href="#valid-patterns">2.4. Valid Patterns for Tokens   sec_2-3-5</a></span></dt><dt><span class="section"><a href="#backquote">2.5. Backquote   sec_2-4-6</a></span></dt><dt><span class="section"><a href="#sharpsign">2.6. Sharpsign   sec_2-4-8</a></span></dt></dl></dd><dt><span class="chapter"><a href="#eval">3. Evaluation and Compilation   chap-3</a></span></dt><dd><dl><dt><span class="section"><a href="#evaluation">3.1. Evaluation   sec_3-1</a></span></dt><dt><span class="section"><a href="#compilation">3.2. Compilation   sec_3-2</a></span></dt><dt><span class="section"><a href="#declarations">3.3. Declarations   sec_3-3</a></span></dt><dt><span class="section"><a href="#lalist">3.4. Lambda Lists   sec_3-4</a></span></dt></dl></dd><dt><span class="chapter"><a href="#types-classes">4. Types and Classes   chap-4</a></span></dt><dd><dl><dt><span class="section"><a href="#types">4.1. Types sec_4-2</a></span></dt><dt><span class="section"><a href="#classes">4.2. Classes   sec_4-3</a></span></dt><dt><span class="section"><a href="#clos-diff">4.3. Deviations from ANSI CL standard</a></span></dt><dt><span class="section"><a href="#metaclasses">4.4. Standard Metaclasses   sec_4-3-1-1</a></span></dt><dt><span class="section"><a href="#def-class">4.5. Defining Classes   sec_4-3-2</a></span></dt><dt><span class="section"><a href="#redef-class">4.6. Redefining Classes   sec_4-3-6</a></span></dt></dl></dd><dt><span class="chapter"><a href="#data">5. Data and Control Flow   chap-5</a></span></dt><dd><dl><dt><span class="section"><a href="#gen-ref">5.1. Generalized Reference   sec_5-1</a></span></dt><dt><span class="section"><a href="#setf-expansion">5.2. Setf Expansions   sec_5-1-1-2</a></span></dt><dt><span class="section"><a href="#extra-places">5.3. Kinds of Places   sec_5-1-2</a></span></dt><dt><span class="section"><a href="#misc-data">5.4. Miscellaneous</a></span></dt><dt><span class="section"><a href="#defconstant">5.5. Macro <code class="function">DEFCONSTANT</code></a></span></dt><dt><span class="section"><a href="#fcase">5.6. Macro <code class="function">EXT:FCASE</code></a></span></dt><dt><span class="section"><a href="#xor">5.7. Function <code class="function">EXT:XOR</code></a></span></dt><dt><span class="section"><a href="#eq">5.8. Function <code class="function">EQ</code></a></span></dt><dt><span class="section"><a href="#func">5.9. Special Operator <code class="function">FUNCTION</code></a></span></dt></dl></dd><dt><span class="chapter"><a href="#iteration">6. Iteration   chap-6</a></span></dt><dd><dl><dt><span class="section"><a href="#loop">6.1. The LOOP Facility   sec_6-1</a></span></dt><dt><span class="section"><a href="#iter-misc">6.2. Miscellaneous</a></span></dt></dl></dd><dt><span class="chapter"><a href="#objects">7. Objects chap-7</a></span></dt><dd><dl><dt><span class="section"><a href="#std-meth-combo">7.1. Standard Method Combination   sec_7-6-6-2</a></span></dt></dl></dd><dt><span class="chapter"><a href="#structures">8. Structures   chap-8</a></span></dt><dd><dl><dt><span class="section"><a href="#defstruct-options">8.1. The options for <code class="function">DEFSTRUCT</code></a></span></dt><dt><span class="section"><a href="#defstruct-mop">8.2. The structure Meta-Object Protocol</a></span></dt></dl></dd><dt><span class="chapter"><a href="#conditions">9. Conditions   chap-9</a></span></dt><dd><dl><dt><span class="section"><a href="#cond-nl">9.1. Embedded Newlines in Condition Reports   sec_9-1-3-1-3</a></span></dt><dt><span class="section"><a href="#cond-fname">9.2. Mentioning Containing Function in   Condition Reports sec_9-1-3-1-5</a></span></dt><dt><span class="section"><a href="#restarts">9.3. Interfaces to Restarts   sec_9-1-4-2-2</a></span></dt><dt><span class="section"><a href="#assertions">9.4. Assertions   sec_9-1-5</a></span></dt></dl></dd><dt><span class="chapter"><a href="#symbols">10. Symbols chap-10</a></span></dt><dt><span class="chapter"><a href="#packages">11. Packages   chap-11</a></span></dt><dd><dl><dt><span class="section"><a href="#pack-intro">11.1. Introduction to Packages   sec_11-1-1</a></span></dt><dt><span class="section"><a href="#pack-lock">11.2. Constraints on the <strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong> Package   for Conforming Programs - package locking  sec_11-1-2-1-2</a></span></dt><dt><span class="section"><a href="#clupack">11.3. The   <strong class="package"><span class="quote">“<span class="quote">COMMON-LISP-USER</span>”</span></strong> Package   sec_11-1-2-2</a></span></dt><dt><span class="section"><a href="#imppack">11.4. Implementation-Defined Packages   sec_11-1-2-4</a></span></dt><dt><span class="section"><a href="#package-case">11.5. Package Case-Sensitivity</a></span></dt></dl></dd><dt><span class="chapter"><a href="#numbers">12. Numbers chap-12</a></span></dt><dd><dl><dt><span class="section"><a href="#num-types">12.1. Numeric Types</a></span></dt><dt><span class="section"><a href="#num-concepts">12.2. Number Concepts   sec_12-1</a></span></dt></dl></dd><dt><span class="chapter"><a href="#characters">13. Characters   chap-13</a></span></dt><dd><dl><dt><span class="section"><a href="#char-intro">13.1. Introduction to Characters   sec_13-1</a></span></dt><dt><span class="section"><a href="#char-sets">13.2. Character sets</a></span></dt><dt><span class="section"><a href="#char-script">13.3. Character Scripts   sec_13-1-2-1</a></span></dt><dt><span class="section"><a href="#char-attrib">13.4. Character Attributes   sec_13-1-3</a></span></dt><dt><span class="section"><a href="#graph-char">13.5. Graphic Characters   sec_13-1-4-1</a></span></dt><dt><span class="section"><a href="#alpha-char">13.6. Alphabetic Characters   sec_13-1-4-2</a></span></dt><dt><span class="section"><a href="#char-case">13.7. Characters With Case   sec_13-1-4-3</a></span></dt><dt><span class="section"><a href="#num-char">13.8. Numeric Characters   sec_13-1-4-4</a></span></dt><dt><span class="section"><a href="#char-ord">13.9. Ordering of Characters   sec_13-1-6</a></span></dt><dt><span class="section"><a href="#char-names">13.10. Character Names   sec_13-1-7</a></span></dt><dt><span class="section"><a href="#clhs-newline">13.11. Treatment of Newline during Input and Output   sec_13-1-8</a></span></dt><dt><span class="section"><a href="#char-int">13.12. Character Encodings   sec_13-1-9</a></span></dt><dt><span class="section"><a href="#script-ext">13.13. Documentation of Implementation-Defined Scripts   sec_13-1-10</a></span></dt><dt><span class="section"><a href="#char-platform-dep">13.14. Platform-Dependent Characters</a></span></dt><dt><span class="section"><a href="#char-bits">13.15. Obsolete Constants</a></span></dt></dl></dd><dt><span class="chapter"><a href="#conses">14. Conses chap-14</a></span></dt><dd><dl><dt><span class="section"><a href="#cons-list">14.1. Conses as Lists   sec_14-1-2</a></span></dt></dl></dd><dt><span class="chapter"><a href="#arrays">15. Arrays chap-15</a></span></dt><dd><dl><dt><span class="section"><a href="#array-elts">15.1. Array Elements   sec_15-1-1</a></span></dt></dl></dd><dt><span class="chapter"><a href="#strings">16. Strings chap-16</a></span></dt><dd><dl><dt><span class="section"><a href="#string-misc">16.1. Miscellaneous</a></span></dt></dl></dd><dt><span class="chapter"><a href="#sequences">17. Sequences   chap-17</a></span></dt><dd><dl><dt><span class="section"><a href="#seq-func-ext">17.1. Additional Functions</a></span></dt><dt><span class="section"><a href="#seq-macro-ext">17.2. Additional Macros</a></span></dt><dt><span class="section"><a href="#nreverse-nreconc">17.3. Functions <code class="function">NREVERSE</code> &amp; <code class="function">NRECONC</code></a></span></dt><dt><span class="section"><a href="#rem-del">17.4. Functions <code class="function">REMOVE</code> &amp; <code class="function">DELETE</code></a></span></dt><dt><span class="section"><a href="#sorting">17.5. Functions <code class="function">SORT</code> &amp; <code class="function">STABLE-SORT</code></a></span></dt></dl></dd><dt><span class="chapter"><a href="#hash">18. Hash Tables chap-18</a></span></dt><dd><dl><dt><span class="section"><a href="#hash-mod-key">18.1. Modifying Hash Table Keys   sec_18-1-2</a></span></dt><dt><span class="section"><a href="#make-hash">18.2. Function <code class="function">MAKE-HASH-TABLE</code></a></span></dt><dt><span class="section"><a href="#defhash">18.3. Macro <code class="function">EXT:DEFINE-HASH-TABLE-TEST</code></a></span></dt><dt><span class="section"><a href="#ht-test">18.4. Function <code class="function">HASH-TABLE-TEST</code></a></span></dt><dt><span class="section"><a href="#dohash">18.5. Macro <code class="function">EXT:DOHASH</code></a></span></dt></dl></dd><dt><span class="chapter"><a href="#filenames">19. Filenames   chap-19</a></span></dt><dd><dl><dt><span class="section"><a href="#path-components">19.1. Pathname Components   sec_19-2-1</a></span></dt><dt><span class="section"><a href="#unspecific">19.2. :UNSPECIFIC as a Component Value  sec_19-2-2-2-3</a></span></dt><dt><span class="section"><a href="#path-external-notation">19.3. External notation</a></span></dt><dt><span class="section"><a href="#log-path">19.4. Logical Pathnames   sec_19-3</a></span></dt><dt><span class="section"><a href="#filename-misc">19.5. Miscellaneous</a></span></dt></dl></dd><dt><span class="chapter"><a href="#files">20. Files chap-20</a></span></dt><dd><dl><dt><span class="section"><a href="#dir-is-not-file">20.1. Directory is <span class="strong"><strong>not</strong></span> a file</a></span></dt><dt><span class="section"><a href="#file-func">20.2. File functions</a></span></dt><dt><span class="section"><a href="#dir-func">20.3. Directory functions</a></span></dt></dl></dd><dt><span class="chapter"><a href="#streams">21. Streams chap-21</a></span></dt><dd><dl><dt><span class="section"><a href="#streams-interactive">21.1. Interactive Streams  sec_21-1-1-1-3</a></span></dt><dt><span class="section"><a href="#terminal">21.2. Terminal interaction</a></span></dt><dt><span class="section"><a href="#bin-io">21.3. Binary Input and Output</a></span></dt><dt><span class="section"><a href="#bulk-io">21.4. Bulk Input and Output</a></span></dt><dt><span class="section"><a href="#non-block-io">21.5. Non-Blocking Input and Output</a></span></dt><dt><span class="section"><a href="#newline-convention">21.6. Newline Convention</a></span></dt><dt><span class="section"><a href="#stream-extfmt">21.7. Function <code class="function">STREAM-EXTERNAL-FORMAT</code></a></span></dt><dt><span class="section"><a href="#stream-eltype">21.8. Function <code class="function">STREAM-ELEMENT-TYPE</code></a></span></dt><dt><span class="section"><a href="#make-stream">21.9. Function <code class="function">EXT:MAKE-STREAM</code></a></span></dt><dt><span class="section"><a href="#file-pos">21.10. Function <code class="function">FILE-POSITION</code></a></span></dt><dt><span class="section"><a href="#elastic-newline">21.11. Function <code class="function">EXT:ELASTIC-NEWLINE</code></a></span></dt><dt><span class="section"><a href="#open">21.12. Function <code class="function">OPEN</code></a></span></dt><dt><span class="section"><a href="#clear-input">21.13. Function <code class="function">CLEAR-INPUT</code></a></span></dt><dt><span class="section"><a href="#close">21.14. Function <code class="function">CLOSE</code></a></span></dt><dt><span class="section"><a href="#open-stream-p">21.15. Function <code class="function">OPEN-STREAM-P</code></a></span></dt><dt><span class="section"><a href="#broadcast-stream">21.16. Class <code class="classname">BROADCAST-STREAM</code></a></span></dt><dt><span class="section"><a href="#stream-buffer">21.17. Functions   <code class="function">EXT:MAKE-BUFFERED-INPUT-STREAM</code>
    and   <code class="function">EXT:MAKE-BUFFERED-OUTPUT-STREAM</code>
     </a></span></dt><dt><span class="section"><a href="#stream-handles">21.18. Function   <code class="function">EXT:STREAM-HANDLES</code></a></span></dt></dl></dd><dt><span class="chapter"><a href="#printer">22. Printer chap-22</a></span></dt><dd><dl><dt><span class="section"><a href="#multi-rep">22.1. Multiple Possible Textual Representations   sec_22-1-1-1</a></span></dt><dt><span class="section"><a href="#write-float-decimal">22.2. Printing Floats   sec_22-1-3-1-3</a></span></dt><dt><span class="section"><a href="#spacecharprint">22.3. Printing Characters   sec_22-1-3-2</a></span></dt><dt><span class="section"><a href="#sym-pack-prefix">22.4. Package Prefixes for Symbols   sec_22-1-3-3-1</a></span></dt><dt><span class="section"><a href="#print-vector">22.5. Printing Other Vectors   sec_22-1-3-7</a></span></dt><dt><span class="section"><a href="#print-array">22.6. Printing Other Arrays   sec_22-1-3-8</a></span></dt><dt><span class="section"><a href="#clpp">22.7. The Lisp Pretty Printer   sec_22-2</a></span></dt><dt><span class="section"><a href="#print-formatted">22.8. Formatted Output   sec_22-3</a></span></dt><dt><span class="section"><a href="#write">22.9. Functions <code class="function">WRITE</code> &amp; <code class="function">WRITE-TO-STRING</code></a></span></dt><dt><span class="section"><a href="#print-unreadable-object">22.10. Macro <code class="function">PRINT-UNREADABLE-OBJECT</code></a></span></dt><dt><span class="section"><a href="#print-misc">22.11. Miscellaneous Issues</a></span></dt></dl></dd><dt><span class="chapter"><a href="#reader">23. Reader chap-23</a></span></dt><dd><dl><dt><span class="section"><a href="#rt-case">23.1. Effect of Readtable Case on the Lisp Reader   sec_23-1-2</a></span></dt><dt><span class="section"><a href="#recursive-p">23.2. The <em class="replaceable"><code>recursive-p</code></em> argument   sec_23-1-3-2</a></span></dt></dl></dd><dt><span class="chapter"><a href="#system">24. System Construction   chap-24</a></span></dt><dd><dl><dt><span class="section"><a href="#compilefile">24.1. Function <code class="function">COMPILE-FILE</code></a></span></dt><dt><span class="section"><a href="#compile-file-path">24.2. Function <code class="function">COMPILE-FILE-PATHNAME</code></a></span></dt><dt><span class="section"><a href="#require">24.3. Function <code class="function">REQUIRE</code></a></span></dt><dt><span class="section"><a href="#loadfile">24.4. Function <code class="function">LOAD</code></a></span></dt><dt><span class="section"><a href="#features">24.5. Variable <code class="varname">*FEATURES*</code></a></span></dt><dt><span class="section"><a href="#featurep">24.6. Function <code class="function">EXT:FEATUREP</code>   [CLRFI-1]</a></span></dt><dt><span class="section"><a href="#compiled-file-p">24.7. Function <code class="function">EXT:COMPILED-FILE-P</code>   [CLRFI-2]</a></span></dt></dl></dd><dt><span class="chapter"><a href="#environment">25. Environment   chap-25</a></span></dt><dd><dl><dt><span class="section"><a href="#repl">25.1. Top Level Loop   sec_25-1-1</a></span></dt><dt><span class="section"><a href="#debugger">25.2. Debugging Utilities   sec_25-1-2</a></span></dt><dt><span class="section"><a href="#environment-enq">25.3. Environment Inquiry   sec_25-1-3</a></span></dt><dt><span class="section"><a href="#clock">25.4. Time sec_25-1-4</a></span></dt></dl></dd><dt><span class="chapter"><a href="#glossary">26. Glossary   chap-26</a></span></dt><dt><span class="chapter"><a href="#appendix">27. Appendix   chap-a</a></span></dt><dt><span class="chapter"><a href="#issues">28. X3J13 Issue Index    [CLHS-ic]</a></span></dt></dl></dd><dt><span class="part"><a href="#ext-standard">II. Common Portable Extensions</a></span></dt><dd><dl><dt><span class="chapter"><a href="#mop-chap">29. Meta-Object Protocol</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-intro">29.1. Introduction</a></span></dt><dt><span class="section"><a href="#mop-overview">29.2. Overview</a></span></dt><dt><span class="section"><a href="#mop-classes">29.3. Classes</a></span></dt><dt><span class="section"><a href="#mop-sd">29.4. Slot Definitions</a></span></dt><dt><span class="section"><a href="#mop-gf">29.5. Generic Functions</a></span></dt><dt><span class="section"><a href="#mop-meth">29.6. Methods</a></span></dt><dt><span class="section"><a href="#mop-accessors">29.7. Accessor Methods</a></span></dt><dt><span class="section"><a href="#mop-specializers">29.8. Specializers</a></span></dt><dt><span class="section"><a href="#mop-meth-comb">29.9. Method Combinations</a></span></dt><dt><span class="section"><a href="#mop-slot-access">29.10. Slot Access</a></span></dt><dt><span class="section"><a href="#mop-dep-maint">29.11. Dependent Maintenance</a></span></dt><dt><span class="section"><a href="#mop-clisp">29.12. Deviations from AMOP</a></span></dt></dl></dd><dt><span class="chapter"><a href="#gray">30. Gray streams</a></span></dt><dd><dl><dt><span class="section"><a href="#gray-overview">30.1. Overview</a></span></dt><dt><span class="section"><a href="#gray-classes">30.2. Defined classes</a></span></dt><dt><span class="section"><a href="#gray-gf-general">30.3. General generic functions</a></span></dt><dt><span class="section"><a href="#gray-gf-char-in">30.4. Generic functions for character input</a></span></dt><dt><span class="section"><a href="#gray-gf-char-out">30.5. Generic functions for character output</a></span></dt><dt><span class="section"><a href="#gray-gf-byte-in">30.6. Generic functions for binary input</a></span></dt><dt><span class="section"><a href="#gray-gf-byte-out">30.7. Generic functions for binary output</a></span></dt><dt><span class="section"><a href="#fill-stream">30.8. Class <code class="classname">EXT:FILL-STREAM</code></a></span></dt></dl></dd></dl></dd><dt><span class="part"><a href="#ext-clisp">III. Extensions Specific to <span class="command"><strong>CLISP</strong></span></a></span></dt><dd><dl><dt><span class="chapter"><a href="#ext-p-indep">31. Platform Independent Extensions</a></span></dt><dd><dl><dt><span class="section"><a href="#custom-init-fini">31.1. Customizing <span class="command"><strong>CLISP</strong></span> Process   Initialization and Termination</a></span></dt><dt><span class="section"><a href="#image">31.2. Saving an Image</a></span></dt><dt><span class="section"><a href="#quit">31.3. Quitting <span class="command"><strong>CLISP</strong></span></a></span></dt><dt><span class="section"><a href="#i18n">31.4. Internationalization of <span class="command"><strong>CLISP</strong></span></a></span></dt><dt><span class="section"><a href="#encoding">31.5. Encodings</a></span></dt><dt><span class="section"><a href="#gstream">31.6. Generic streams</a></span></dt><dt><span class="section"><a href="#weak">31.7. Weak Objects</a></span></dt><dt><span class="section"><a href="#final">31.8. Finalization</a></span></dt><dt><span class="section"><a href="#prompt">31.9. The Prompt</a></span></dt><dt><span class="section"><a href="#ansi">31.10. Maximum ANSI CL compliance</a></span></dt><dt><span class="section"><a href="#macros3">31.11. Additional Fancy Macros and Functions</a></span></dt><dt><span class="section"><a href="#customize">31.12. Customizing <span class="command"><strong>CLISP</strong></span> behavior</a></span></dt><dt><span class="section"><a href="#code-walk">31.13. Code Walker</a></span></dt></dl></dd><dt><span class="chapter"><a href="#ext-platform">32. Platform Specific Extensions</a></span></dt><dd><dl><dt><span class="section"><a href="#screen">32.1. Random Screen Access</a></span></dt><dt><span class="section"><a href="#modules">32.2. External Modules</a></span></dt><dt><span class="section"><a href="#dffi">32.3. The Foreign Function Call Facility</a></span></dt><dt><span class="section"><a href="#socket">32.4. Socket Streams</a></span></dt><dt><span class="section"><a href="#mt">32.5. Multiple Threads of Execution</a></span></dt><dt><span class="section"><a href="#quickstart">32.6. Quickstarting delivery with <span class="command"><strong>CLISP</strong></span></a></span></dt><dt><span class="section"><a href="#shell">32.7. Shell, Pipes and Printing</a></span></dt><dt><span class="section"><a href="#getenv">32.8. Operating System Environment</a></span></dt></dl></dd><dt><span class="chapter"><a href="#ext-modules">33. Extensions Implemented as Modules</a></span></dt><dd><dl><dt><span class="section"><a href="#asdf">33.1. A System Definition Facility</a></span></dt><dt><span class="section"><a href="#syscalls">33.2. System Calls</a></span></dt><dt><span class="section"><a href="#i18n-mod">33.3. Internationalization of User Programs</a></span></dt><dt><span class="section"><a href="#regexp-mod">33.4. POSIX Regular Expressions</a></span></dt><dt><span class="section"><a href="#readline-mod">33.5. Advanced Readline and History Functionality</a></span></dt><dt><span class="section"><a href="#gdbm">33.6. GDBM - The GNU database manager</a></span></dt><dt><span class="section"><a href="#berkeley-db">33.7. Berkeley DB access</a></span></dt><dt><span class="section"><a href="#dir-key">33.8. Directory Access</a></span></dt><dt><span class="section"><a href="#postgresql">33.9. PostgreSQL Database Access</a></span></dt><dt><span class="section"><a href="#oracle">33.10. Oracle Interface</a></span></dt><dt><span class="section"><a href="#libsvm">33.11. LibSVM Interface</a></span></dt><dt><span class="section"><a href="#pari">33.12. Computer Algebra System PARI</a></span></dt><dt><span class="section"><a href="#matlab">33.13. Matlab Interface</a></span></dt><dt><span class="section"><a href="#netica">33.14. Netica Interface</a></span></dt><dt><span class="section"><a href="#pcre">33.15. Perl Compatible Regular Expressions</a></span></dt><dt><span class="section"><a href="#zlib">33.16. Interface to zlib</a></span></dt><dt><span class="section"><a href="#rawsock">33.17. Raw Socket Access</a></span></dt><dt><span class="section"><a href="#fastcgi">33.18. The FastCGI Interface</a></span></dt><dt><span class="section"><a href="#dbus">33.19. Interface to D-Bus</a></span></dt><dt><span class="section"><a href="#gtk">33.20. GTK Interface</a></span></dt></dl></dd></dl></dd><dt><span class="part"><a href="#internals">IV. Internals of the <span class="command"><strong>CLISP</strong></span> Implementation</a></span></dt><dd><dl><dt><span class="chapter"><a href="#source-files">34. The source files of <span class="command"><strong>CLISP</strong></span></a></span></dt><dd><dl><dt><span class="section"><a href="#src-file-types">34.1. File Types</a></span></dt><dt><span class="section"><a href="#src-preprocessing">34.2. Source Pre-Processing</a></span></dt><dt><span class="section"><a href="#src-files">34.3. Files</a></span></dt></dl></dd><dt><span class="chapter"><a href="#gc">35. Overview of <span class="command"><strong>CLISP</strong></span>'s Garbage Collection</a></span></dt><dd><dl><dt><span class="section"><a href="#internals-intro">35.1. Introduction</a></span></dt><dt><span class="section"><a href="#lisp-obj-in-c">35.2. Lisp objects in <span class="command"><strong>CLISP</strong></span></a></span></dt><dt><span class="section"><a href="#typecodes">35.3. Object Pointer Representations</a></span></dt><dt><span class="section"><a href="#memory-models">35.4. Memory Models</a></span></dt><dt><span class="section"><a href="#gc-safety">35.5. The burden of garbage-collection upon the rest of <span class="command"><strong>CLISP</strong></span></a></span></dt><dt><span class="section"><a href="#foreign-pointers">35.6. Foreign Pointers</a></span></dt><dt><span class="section"><a href="#nextgc-factor">35.7. Forcing or inhibiting Garbage Collections</a></span></dt><dt><span class="section"><a href="#gc-mt">35.8. Garbage Collection and Multithreading</a></span></dt></dl></dd><dt><span class="chapter"><a href="#extend">36. Extending <span class="command"><strong>CLISP</strong></span> Core</a></span></dt><dd><dl><dt><span class="section"><a href="#add-fun">36.1. Adding a built-in function</a></span></dt><dt><span class="section"><a href="#add-var">36.2. Adding a built-in variable</a></span></dt><dt><span class="section"><a href="#recompile">36.3. Recompilation</a></span></dt></dl></dd><dt><span class="chapter"><a href="#bytecode">37. The <span class="command"><strong>CLISP</strong></span> bytecode specification</a></span></dt><dd><dl><dt><span class="section"><a href="#byte-intro">37.1. Introduction</a></span></dt><dt><span class="section"><a href="#vm">37.2. The virtual machine</a></span></dt><dt><span class="section"><a href="#comp-fun">37.3. The structure of compiled functions</a></span></dt><dt><span class="section"><a href="#instr-struct">37.4. The general structure of the instructions</a></span></dt><dt><span class="section"><a href="#instr-set">37.5. The instruction set</a></span></dt><dt><span class="section"><a href="#compiler-introspection">37.6. Examining compiled closures</a></span></dt><dt><span class="section"><a href="#bytecode-design">37.7. Bytecode Design</a></span></dt></dl></dd></dl></dd><dt><span class="part"><a href="#appendices">V. Appendices</a></span></dt><dd><dl><dt><span class="appendix"><a href="#faq">A. Frequently Asked Questions (With Answers)   about <span class="command"><strong>CLISP</strong></span></a></span></dt><dt><span class="appendix"><a href="#fdl">B. GNU Free Documentation License</a></span></dt><dt><span class="appendix"><a href="#gpl">C. GNU General Public License</a></span></dt><dd><dl><dt><span class="section"><a href="#gpl-1">C.1. Preamble</a></span></dt><dt><span class="section"><a href="#gpl-2">C.2. TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION</a></span></dt><dt><span class="section"><a href="#gpl-3">C.3. How to Apply These Terms to Your New Programs</a></span></dt></dl></dd></dl></dd><dt><span class="index"><a href="#idx">Index</a></span></dt><dt><span class="bibliography"><a href="#references">References</a></span></dt></dl></div><div class="list-of-figures"><p><strong>List of Figures</strong></p><dl><dt>29.1. <a href="#mop-mo-cl-inheritance-fig">Inheritance structure of metaobject classes</a></dt><dt>29.2. <a href="#mop-cl-Inheritance-fig">Inheritance structure of class metaobject classes</a></dt><dt>29.3. <a href="#mop-sd-inheritance-fig">Inheritance structure of slot definition metaobject classes</a></dt><dt>29.4. <a href="#mop-gf-inheritance-fig">Inheritance structure of generic function metaobject classes</a></dt><dt>29.5. <a href="#mop-meth-inheritance-fig">Inheritance structure of method metaobject classes</a></dt><dt>29.6. <a href="#mop-specializers-inheritance-fig">Inheritance structure of specializer metaobject classes</a></dt><dt>29.7. <a href="#mop-meth-comb-inheritance-fig">Inheritance structure of method combination metaobject classes</a></dt></dl></div><div class="list-of-tables"><p><strong>List of Tables</strong></p><dl><dt>1. <a href="#conventions-tab">Mark-up conventions</a></dt><dt>3.1. <a href="#eval-limits-table">Function call limits</a></dt><dt>12.1. <a href="#bool-op-table">Boolean operations</a></dt><dt>12.2. <a href="#fixnum-lim-table">Fixnum limits</a></dt><dt>13.1. <a href="#char-code-limit-table">Number of characters</a></dt><dt>13.2. <a href="#standard-char-table">Standard characters</a></dt><dt>13.3. <a href="#semi-standard-char-table">Semi-standard characters</a></dt><dt>13.4. <a href="#extra-named-chars-table">Additional Named Characters</a></dt><dt>13.5. <a href="#ctrl-char-table">Additional syntax for characters with code from    <span class="keycode">#x00</span> to <span class="keycode">#x1F</span>:</a></dt><dt>13.6. <a href="#dos-win32-chars-table">Additional characters (<span class="platform">Win32</span> platform only.)</a></dt><dt>13.7. <a href="#unix-chars-table">Additional characters (<span class="strong"><strong>UNIX</strong></span> platform only.)</a></dt><dt>13.8. <a href="#char-bits-table">Character bit constants (obsolete)</a></dt><dt>15.1. <a href="#array-limit-table">Array limits</a></dt><dt>19.1. <a href="#min-filename-syntax-table">The minimum filename syntax that may be used portably</a></dt><dt>25.1. <a href="#debugger-main-deb-step">Commands common to the main loop, the debugger and the stepper</a></dt><dt>25.2. <a href="#debugger-deb-step">Commands common to the debugger and the stepper</a></dt><dt>25.3. <a href="#debugger-deb-step-1">Commands common to the debugger and the stepper</a></dt><dt>25.4. <a href="#debugger-eval-apply">Commands specific to <code class="function">EVAL</code>/<code class="function">APPLY</code></a></dt><dt>25.5. <a href="#debugger-deb">Commands specific to the debugger</a></dt><dt>25.6. <a href="#debugger-step">Commands specific to the stepper</a></dt><dt>25.7. <a href="#internal-time-units-table">Time granularity</a></dt><dt>29.1. <a href="#mop-inherit-struct">Direct Superclass Relationships   Among The Specified Metaobject Classes</a></dt><dt>29.2. <a href="#class-mo-initargs">Initialization arguments and    accessors for class metaobjects</a></dt><dt>29.3. <a href="#slotd-mo-initargs">Initialization arguments and   accessors for slot definition metaobjects</a></dt><dt>29.4. <a href="#gf-mo-initargs">Initialization arguments and accessors   for generic function metaobjects</a></dt><dt>29.5. <a href="#mop-meth-initargs">Initialization arguments and   accessors for method metaobjects</a></dt><dt>29.6. <a href="#mop-sa-instance-struct-table">The correspondence between slot access function and   underlying slot access generic function</a></dt><dt>35.1. <a href="#mem-models-comb-typecodes">Memory models with <span class="strong"><strong><code class="option">TYPECODES</code></strong></span></a></dt><dt>35.2. <a href="#mem-models-comb-heapcodes">Memory models with <span class="strong"><strong><code class="option">HEAPCODES</code></strong></span></a></dt></dl></div><div class="list-of-examples"><p><strong>List of Examples</strong></p><dl><dt>25.1. <a href="#trace-call-id">Identifying Individual Calls in <code class="function">TRACE</code></a></dt><dt>30.1. <a href="#ex-fill-stream">Example of <code class="classname">EXT:FILL-STREAM</code> usage</a></dt><dt>32.1. <a href="#mod-set-ex-bindings">Create a module set with GNU libc bindings</a></dt><dt>32.2. <a href="#dffi-simple">Simple declarations and access</a></dt><dt>32.3. <a href="#dffi-extern-var">External <span class="command"><strong>C</strong></span> variable and some accesses</a></dt><dt>32.4. <a href="#dffi-extern-func1">Calling an external function</a></dt><dt>32.5. <a href="#dffi-extern-func2">Another example for calling an external function</a></dt><dt>32.6. <a href="#dffi-ex-macro">Accessing <span class="command"><strong>cpp</strong></span> macros</a></dt><dt>32.7. <a href="#ex-call-in">Calling Lisp from <span class="command"><strong>C</strong></span></a></dt><dt>32.8. <a href="#ex-call-in-dll">Calling Lisp from <span class="command"><strong>C</strong></span> dynamically</a></dt><dt>32.9. <a href="#dffi-gethostname">Variable size arguments:   calling <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/gethostname.html"><code class="function">gethostname</code></a> from <span class="command"><strong>CLISP</strong></span></a></dt><dt>32.10. <a href="#dffi-dll-var">Accessing variables in shared libraries</a></dt><dt>32.11. <a href="#ex-dffi-validity">Controlling validity of resources</a></dt><dt>32.12. <a href="#ex-dffi-float">Floating point arrays</a></dt><dt>32.13. <a href="#socket-ex-server">Lisp read-eval-print loop server</a></dt><dt>32.14. <a href="#socket-ex-client">Lisp <span class="command"><strong>HTTP</strong></span> client</a></dt><dt>33.1. <a href="#ex-re-match"><code class="function">REGEXP:MATCH</code></a></dt><dt>33.2. <a href="#ex-re-quote"><code class="function">REGEXP:REGEXP-QUOTE</code></a></dt><dt>33.3. <a href="#re-count-shell-users">Count unix shell users</a></dt></dl></div><div class="preface"><div class="titlepage"><div><div><h1 class="title"><a id="overview"></a>Overview</h1></div></div></div><p>These notes discuss the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> implementation of <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> by <span class="author"><span class="firstname">Bruno</span> <span class="surname">Haible</span></span>
 and <span class="author"><span class="firstname">Michael</span> <span class="surname">Stoll</span></span>. The current maintainers are <span class="author"><span class="firstname">Bruno</span> <span class="surname">Haible</span></span> and <span class="author"><span class="firstname">Sam</span> <span class="surname">Steingold</span></span>.</p><p>This implementation is mostly conforming to the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>]
 available on-line as the [<span class="citation"><a class="link" href="#CLHS" title="Common Lisp HyperSpec">Common Lisp HyperSpec</a></span>] (but the printed <a class="ulink" href="http://www.ansi.org/" target="_top"><acronym class="acronym" title="The American National Standards Institute">ANSI</acronym></a> document
 remains the authoritative source of information).  [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] supersedes
 the earlier specifications <a class="xref" href="#CLtL1" title="Common Lisp: the Language (1st Edition)">[<abbr class="abbrev">CLtL1</abbr>]</a> and <a class="xref" href="#CLtL2" title="Common Lisp: the Language (2nd Edition)">[<abbr class="abbrev">CLtL2</abbr>]</a>.</p><p>The first part of these notes, <a class="xref" href="#clhs-chapters" title="Part I. Chapters or the Common Lisp HyperSpec">Part I, “Chapters or the Common Lisp HyperSpec”</a>,
 is indexed in parallel to the [<span class="citation"><a class="link" href="#CLHS" title="Common Lisp HyperSpec">Common Lisp HyperSpec</a></span>] and documents how <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
 implements the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>].</p><p>The second part, <a class="xref" href="#ext-standard" title="Part II. Common Portable Extensions">Part II, “Common Portable Extensions”</a>, documents the
 common extensions to the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>], specifically <a class="link" href="#mop-chap" title="Chapter 29. Meta-Object Protocol">Meta-Object Protocol</a> and <a class="link" href="#gray" title="Chapter 30. Gray streams"><strong class="package"><span class="quote">“<span class="quote">GRAY</span>”</span></strong></a>
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s.</p><p>The third part, <a class="xref" href="#ext-clisp" title="Part III. Extensions Specific to CLISP">Part III, “Extensions Specific to <span class="command"><strong>CLISP</strong></span>”</a>, documents the
 <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>-specific extensions, e.g., <a class="xref" href="#socket" title="32.4. Socket Streams">Section 32.4, “Socket Streams”</a>.</p><p>The fourth part, <a class="xref" href="#internals" title="Part IV. Internals of the CLISP Implementation">Part IV, “Internals of the <span class="command"><strong>CLISP</strong></span> Implementation”</a>, is intended mostly
 for developers as it documents the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> internals, e.g., <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion,
 adding new built-ins, and the <a href="impnotes.html#bytecode" class="olink">bytecode</a>s generated by the compiler
 (i.e., what is printed by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_disassemble.html" target="_top"><code class="function">DISASSEMBLE</code></a>).</p></div><div class="preface"><div class="titlepage"><div><div><h1 class="title"><a id="conventions"></a>Conventions</h1></div></div></div><p>The following is the mark-up notations used in this document:
 </p><div class="table"><a id="conventions-tab"></a><p class="title"><strong>Table 1. Mark-up conventions</strong></p><div class="table-contents"><table class="table" summary="Mark-up conventions" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="center">Object Kind</th><th align="center">Example</th></tr></thead><tbody><tr><td align="center">Function</td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CAR</code></a></td></tr><tr><td align="center">Variable</td><td align="center"><a href="impnotes.html#load-paths" class="olink"><code class="varname">CUSTOM:*LOAD-PATHS*</code></a></td></tr><tr><td align="center">Formal Argument</td><td align="center"><em class="replaceable"><code>x</code></em></td></tr><tr><td align="center">Keyword</td><td align="center"><code class="constant">:EOF</code></td></tr><tr><td align="center">Number</td><td align="center"><code class="literal">0</code></td></tr><tr><td align="center">Character</td><td align="center"><span class="keysym">#\Newline</span></td></tr><tr><td align="center">Class, type</td><td align="center"><a class="link" href="#regexp-api" title="Regular Expression API"><code class="classname">REGEXP:MATCH</code></a></td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> instruction</td><td align="center"><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-4-1.html"><code class="literal">~A</code></a></td></tr><tr><td align="center">Standard <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> keyword</td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a></td></tr><tr><td align="center">Declaration</td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_ftype.html" target="_top"><code class="literal">FTYPE</code></a></td></tr><tr><td align="center">Package</td><td align="center"><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-2.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP-USER</span>”</span></strong></a></td></tr><tr><td align="center">Real file</td><td align="center"><a class="link" href="#config-lisp"><code class="filename">config.lisp</code></a></td></tr><tr><td align="center">Abstract file</td><td align="center"><code class="filename">#P".c"</code></td></tr><tr><td align="center">Code (you are likely to type it)</td><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_cons.html" target="_top"><code class="function">CONS</code></a> 1 2)</code></td></tr><tr><td align="center">Data (<a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> is likely to print it)</td><td align="center"><span class="data"><code class="literal">#(1 2 3)</code></span></td></tr><tr><td align="center">Program listing</td><td align="center"><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defun.html" target="_top"><code class="function">DEFUN</code></a> cycle-length (n <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> (len 1) (top 0))
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_cond.html" target="_top"><code class="function">COND</code></a> ((<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eqcm_sleq__lteqcm_gteq.html" target="_top"><code class="function">=</code></a> n 1) (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_values.html" target="_top"><code class="function">VALUES</code></a> len top))
        ((<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_evenpcm_oddp.html" target="_top"><code class="function">EVENP</code></a> n) (cycle-length (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_ash.html" target="_top"><code class="function">ASH</code></a> n -1) (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_1plcm_1-.html" target="_top"><code class="function">1+</code></a> len) (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_maxcm_min.html" target="_top"><code class="function">MAX</code></a> top n)))
        (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET</code></a> ((next (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_1plcm_1-.html" target="_top"><code class="function">1+</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_st.html" target="_top"><code class="function">*</code></a> 3 n))))
             (cycle-length next (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_1plcm_1-.html" target="_top"><code class="function">1+</code></a> len) (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_maxcm_min.html" target="_top"><code class="function">MAX</code></a> top next))))))</pre></td></tr><tr><td align="center">Bytecode instruction</td><td align="center"><span class="byte"><code class="literal">(STOREV <em class="replaceable"><code>k</code></em> <em class="replaceable"><code>m</code></em>)</code></span></td></tr><tr><td align="center">First mention of an entity</td><td align="center"><strong class="first"><em class="firstterm">firstterm</em></strong></td></tr><tr><td align="center">External <a href="impnotes.html#modules" class="olink">module</a></td><td align="center"><span class="module"><a class="filename" href="#libsvm" title="33.11. LibSVM Interface"><code class="filename">libsvm</code></a></span>, <span class="module"><a href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/bindings/glibc/"><code class="filename">bindings/glibc</code></a></span></td></tr><tr><td align="center">Command line argument</td><td align="center"><code class="option"><a href="clisp.html#opt-exec-expr" class="olink">-x</a></code></td></tr><tr><td align="center">Interaction</td><td align="center"><pre class="screen">Computer output
<strong><code class="prompt">Prompt:</code></strong> <big><strong class="userinput"><code>user input</code></strong></big></pre>
    </td></tr></tbody></table></div></div><p><br class="table-break" /></p></div><div class="part"><div class="titlepage"><div><div><h1 class="title"><a id="clhs-chapters"></a>Part I. Chapters or the [<span class="citation"><a class="link" href="#CLHS" title="Common Lisp HyperSpec">Common Lisp HyperSpec</a></span>]</h1></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="chapter"><a href="#intro">1. Introduction   chap-1</a></span></dt><dd><dl><dt><span class="section"><a href="#spec-symb">1.1. Special Symbols   sec_1-4-1-3</a></span></dt><dt><span class="section"><a href="#error-terms">1.2. Error Terminology   sec_1-4-2</a></span></dt><dt><span class="section"><a href="#cl-symb">1.3. Symbols in the Package <strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong>   sec_1-9</a></span></dt></dl></dd><dt><span class="chapter"><a href="#syntax">2. Syntax chap-2</a></span></dt><dd><dl><dt><span class="section"><a href="#std-char">2.1. Standard Characters   sec_2-1-3</a></span></dt><dt><span class="section"><a href="#reader-alg">2.2. Reader Algorithm   sec_2-2</a></span></dt><dt><span class="section"><a href="#tokens">2.3. Symbols as Tokens   sec_2-3-4</a></span></dt><dt><span class="section"><a href="#valid-patterns">2.4. Valid Patterns for Tokens   sec_2-3-5</a></span></dt><dt><span class="section"><a href="#backquote">2.5. Backquote   sec_2-4-6</a></span></dt><dt><span class="section"><a href="#sharpsign">2.6. Sharpsign   sec_2-4-8</a></span></dt><dd><dl><dt><span class="section"><a href="#sharpsign-backslash">2.6.1. Sharpsign Backslash   sec_2-4-8-1</a></span></dt><dt><span class="section"><a href="#sharpsign-less-than">2.6.2. Sharpsign Less-Than-Sign   sec_2-4-8-20</a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="#eval">3. Evaluation and Compilation   chap-3</a></span></dt><dd><dl><dt><span class="section"><a href="#evaluation">3.1. Evaluation   sec_3-1</a></span></dt><dd><dl><dt><span class="section"><a href="#eval-environ">3.1.1. Introduction to Environments   sec_3-1-1</a></span></dt><dt><span class="section"><a href="#sym-forms">3.1.2. Symbols as Forms   sec_3-1-2-1-1</a></span></dt><dt><span class="section"><a href="#cons-forms">3.1.3. Conses as Forms   sec_3-1-2-1-2</a></span></dt><dt><span class="section"><a href="#specforms">3.1.4. Special Forms   sec_3-1-2-1-2-1</a></span></dt><dt><span class="section"><a href="#funforms">3.1.5. Function Forms   sec_3-1-2-1-2-3</a></span></dt><dt><span class="section"><a href="#defun">3.1.6. Macros <code class="function">DEFUN</code> &amp; <code class="function">DEFMACRO</code></a></span></dt></dl></dd><dt><span class="section"><a href="#compilation">3.2. Compilation   sec_3-2</a></span></dt><dd><dl><dt><span class="section"><a href="#compiler-terms">3.2.1. Compiler Terminology   sec_3-2-1</a></span></dt><dt><span class="section"><a href="#compilation-semantics">3.2.2. Compilation Semantics   sec_3-2-2</a></span></dt><dt><span class="section"><a href="#similarity">3.2.3. Definition of Similarity   sec_3-2-4-2-2</a></span></dt><dt><span class="section"><a href="#compile-errors">3.2.4. Exceptional Situations in the Compiler   sec_3-2-5</a></span></dt></dl></dd><dt><span class="section"><a href="#declarations">3.3. Declarations   sec_3-3</a></span></dt><dd><dl><dt><span class="section"><a href="#decl-min">3.3.1. Minimal Declaration Processing Requirements   sec_3-3-1</a></span></dt><dt><span class="section"><a href="#spec-decl">3.3.2. Declaration <code class="literal">SPECIAL</code></a></span></dt><dt><span class="section"><a href="#constant-notinline">3.3.3. Declaration <code class="literal">EXT:CONSTANT-NOTINLINE</code></a></span></dt><dt><span class="section"><a href="#constantp">3.3.4. Function <code class="function">CONSTANTP</code></a></span></dt><dt><span class="section"><a href="#safety-decl">3.3.5. Declaration <code class="literal">SAFETY</code></a></span></dt><dt><span class="section"><a href="#compile-decl">3.3.6. Declaration <code class="code">(COMPILE)</code></a></span></dt><dt><span class="section"><a href="#space-decl">3.3.7. Declaration <code class="literal">SPACE</code></a></span></dt></dl></dd><dt><span class="section"><a href="#lalist">3.4. Lambda Lists   sec_3-4</a></span></dt><dd><dl><dt><span class="section"><a href="#boa-lalist">3.4.1. Boa Lambda Lists   sec_3-4-6</a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="#types-classes">4. Types and Classes   chap-4</a></span></dt><dd><dl><dt><span class="section"><a href="#types">4.1. Types sec_4-2</a></span></dt><dd><dl><dt><span class="section"><a href="#type-spec">4.1.1. Type Specifiers   sec_4-2-3</a></span></dt></dl></dd><dt><span class="section"><a href="#classes">4.2. Classes   sec_4-3</a></span></dt><dt><span class="section"><a href="#clos-diff">4.3. Deviations from ANSI CL standard</a></span></dt><dt><span class="section"><a href="#metaclasses">4.4. Standard Metaclasses   sec_4-3-1-1</a></span></dt><dt><span class="section"><a href="#def-class">4.5. Defining Classes   sec_4-3-2</a></span></dt><dt><span class="section"><a href="#redef-class">4.6. Redefining Classes   sec_4-3-6</a></span></dt></dl></dd><dt><span class="chapter"><a href="#data">5. Data and Control Flow   chap-5</a></span></dt><dd><dl><dt><span class="section"><a href="#gen-ref">5.1. Generalized Reference   sec_5-1</a></span></dt><dt><span class="section"><a href="#setf-expansion">5.2. Setf Expansions   sec_5-1-1-2</a></span></dt><dt><span class="section"><a href="#extra-places">5.3. Kinds of Places   sec_5-1-2</a></span></dt><dt><span class="section"><a href="#misc-data">5.4. Miscellaneous</a></span></dt><dt><span class="section"><a href="#defconstant">5.5. Macro <code class="function">DEFCONSTANT</code></a></span></dt><dd><dl><dt><span class="section"><a href="#defconstant-similar">5.5.1. Variable <code class="varname">CUSTOM:*SUPPRESS-SIMILAR-CONSTANT-REDEFINITION-WARNING*</code></a></span></dt></dl></dd><dt><span class="section"><a href="#fcase">5.6. Macro <code class="function">EXT:FCASE</code></a></span></dt><dt><span class="section"><a href="#xor">5.7. Function <code class="function">EXT:XOR</code></a></span></dt><dt><span class="section"><a href="#eq">5.8. Function <code class="function">EQ</code></a></span></dt><dt><span class="section"><a href="#func">5.9. Special Operator <code class="function">FUNCTION</code></a></span></dt></dl></dd><dt><span class="chapter"><a href="#iteration">6. Iteration   chap-6</a></span></dt><dd><dl><dt><span class="section"><a href="#loop">6.1. The LOOP Facility   sec_6-1</a></span></dt><dd><dl><dt><span class="section"><a href="#loop-termination">6.1.1. Mixing Termination Test Clauses   sec_6-1-4</a></span></dt><dt><span class="section"><a href="#loop-inter-var-finally">6.1.2. Iteration variables in the loop epilogue</a></span></dt><dt><span class="section"><a href="#loop-ansi">6.1.3. Backward Compatibility</a></span></dt></dl></dd><dt><span class="section"><a href="#iter-misc">6.2. Miscellaneous</a></span></dt></dl></dd><dt><span class="chapter"><a href="#objects">7. Objects chap-7</a></span></dt><dd><dl><dt><span class="section"><a href="#std-meth-combo">7.1. Standard Method Combination   sec_7-6-6-2</a></span></dt></dl></dd><dt><span class="chapter"><a href="#structures">8. Structures   chap-8</a></span></dt><dd><dl><dt><span class="section"><a href="#defstruct-options">8.1. The options for <code class="function">DEFSTRUCT</code></a></span></dt><dd><dl><dt><span class="section"><a href="#defstruct-print-function">8.1.1. The <code class="constant">:PRINT-FUNCTION</code> option</a></span></dt><dt><span class="section"><a href="#defstruct-inherit">8.1.2. The <code class="constant">:INHERIT</code> option</a></span></dt></dl></dd><dt><span class="section"><a href="#defstruct-mop">8.2. The structure Meta-Object Protocol</a></span></dt></dl></dd><dt><span class="chapter"><a href="#conditions">9. Conditions   chap-9</a></span></dt><dd><dl><dt><span class="section"><a href="#cond-nl">9.1. Embedded Newlines in Condition Reports   sec_9-1-3-1-3</a></span></dt><dt><span class="section"><a href="#cond-fname">9.2. Mentioning Containing Function in   Condition Reports sec_9-1-3-1-5</a></span></dt><dt><span class="section"><a href="#restarts">9.3. Interfaces to Restarts   sec_9-1-4-2-2</a></span></dt><dt><span class="section"><a href="#assertions">9.4. Assertions   sec_9-1-5</a></span></dt></dl></dd><dt><span class="chapter"><a href="#symbols">10. Symbols chap-10</a></span></dt><dt><span class="chapter"><a href="#packages">11. Packages   chap-11</a></span></dt><dd><dl><dt><span class="section"><a href="#pack-intro">11.1. Introduction to Packages   sec_11-1-1</a></span></dt><dd><dl><dt><span class="section"><a href="#make-pack">11.1.1. Function <code class="function">MAKE-PACKAGE</code></a></span></dt><dt><span class="section"><a href="#defpack">11.1.2. Macro <code class="function">DEFPACKAGE</code></a></span></dt><dt><span class="section"><a href="#re-export">11.1.3. Function <code class="function">EXT:RE-EXPORT</code></a></span></dt><dt><span class="section"><a href="#pack-inverted">11.1.4. Function <code class="function">EXT:PACKAGE-CASE-INVERTED-P</code></a></span></dt><dt><span class="section"><a href="#pack-sensitive">11.1.5. Function <code class="function">EXT:PACKAGE-CASE-SENSITIVE-P</code></a></span></dt></dl></dd><dt><span class="section"><a href="#pack-lock">11.2. Constraints on the <strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong> Package   for Conforming Programs - package locking  sec_11-1-2-1-2</a></span></dt><dt><span class="section"><a href="#clupack">11.3. The   <strong class="package"><span class="quote">“<span class="quote">COMMON-LISP-USER</span>”</span></strong> Package   sec_11-1-2-2</a></span></dt><dt><span class="section"><a href="#imppack">11.4. Implementation-Defined Packages   sec_11-1-2-4</a></span></dt><dt><span class="section"><a href="#package-case">11.5. Package Case-Sensitivity</a></span></dt><dd><dl><dt><span class="section"><a href="#cs-clu">11.5.1. User Package for the Case-sensitive World</a></span></dt><dt><span class="section"><a href="#cs-pack-name">11.5.2. Package Names</a></span></dt><dt><span class="section"><a href="#cs-gensym-kwd">11.5.3. Gensyms and Keywords</a></span></dt><dt><span class="section"><a href="#case-sensitive-migration">11.5.4. Migration Tips</a></span></dt><dt><span class="section"><a href="#case-sensitive-startup">11.5.5. Using case-sensitive packages by default</a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="#numbers">12. Numbers chap-12</a></span></dt><dd><dl><dt><span class="section"><a href="#num-types">12.1. Numeric Types</a></span></dt><dt><span class="section"><a href="#num-concepts">12.2. Number Concepts   sec_12-1</a></span></dt><dd><dl><dt><span class="section"><a href="#num-ops">12.2.1. Numeric Operations   sec_12-1-1</a></span></dt><dt><span class="section"><a href="#num-const">12.2.2. Implementation-Dependent Numeric Constants   sec_12-1-2</a></span></dt><dt><span class="section"><a href="#float-subst">12.2.3. Rule of Float Substitutability   sec_12-1-3-3</a></span></dt><dt><span class="section"><a href="#float-comp">12.2.4. Floating-point Computations   sec_12-1-4</a></span></dt><dt><span class="section"><a href="#complex-comp">12.2.5. Complex Computations   sec_12-1-5</a></span></dt><dt><span class="section"><a href="#complex-rational">12.2.6. Rule of Canonical Representation   for Complex Rationals sec_12-1-5-3</a></span></dt><dt><span class="section"><a href="#random-state">12.2.7. Random-State Operations   sec_12-1-7</a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="#characters">13. Characters   chap-13</a></span></dt><dd><dl><dt><span class="section"><a href="#char-intro">13.1. Introduction to Characters   sec_13-1</a></span></dt><dd><dl><dt><span class="section"><a href="#char-code">13.1.1. Function <code class="function">CHAR-CODE</code></a></span></dt><dt><span class="section"><a href="#base-char">13.1.2. Type <code class="classname">BASE-CHAR</code></a></span></dt><dt><span class="section"><a href="#char-width">13.1.3. Function <code class="function">EXT:CHAR-WIDTH</code></a></span></dt></dl></dd><dt><span class="section"><a href="#char-sets">13.2. Character sets</a></span></dt><dt><span class="section"><a href="#char-script">13.3. Character Scripts   sec_13-1-2-1</a></span></dt><dt><span class="section"><a href="#char-attrib">13.4. Character Attributes   sec_13-1-3</a></span></dt><dd><dl><dt><span class="section"><a href="#input-char">13.4.1. Input Characters</a></span></dt></dl></dd><dt><span class="section"><a href="#graph-char">13.5. Graphic Characters   sec_13-1-4-1</a></span></dt><dt><span class="section"><a href="#alpha-char">13.6. Alphabetic Characters   sec_13-1-4-2</a></span></dt><dt><span class="section"><a href="#char-case">13.7. Characters With Case   sec_13-1-4-3</a></span></dt><dd><dl><dt><span class="section"><a href="#char-invertcase">13.7.1. Function <code class="function">EXT:CHAR-INVERTCASE</code></a></span></dt><dt><span class="section"><a href="#char-ext">13.7.2. Case of Implementation-Defined Characters   sec_13-1-4-3-4</a></span></dt></dl></dd><dt><span class="section"><a href="#num-char">13.8. Numeric Characters   sec_13-1-4-4</a></span></dt><dt><span class="section"><a href="#char-ord">13.9. Ordering of Characters   sec_13-1-6</a></span></dt><dt><span class="section"><a href="#char-names">13.10. Character Names   sec_13-1-7</a></span></dt><dt><span class="section"><a href="#clhs-newline">13.11. Treatment of Newline during Input and Output   sec_13-1-8</a></span></dt><dt><span class="section"><a href="#char-int">13.12. Character Encodings   sec_13-1-9</a></span></dt><dt><span class="section"><a href="#script-ext">13.13. Documentation of Implementation-Defined Scripts   sec_13-1-10</a></span></dt><dt><span class="section"><a href="#char-platform-dep">13.14. Platform-Dependent Characters</a></span></dt><dt><span class="section"><a href="#char-bits">13.15. Obsolete Constants</a></span></dt></dl></dd><dt><span class="chapter"><a href="#conses">14. Conses chap-14</a></span></dt><dd><dl><dt><span class="section"><a href="#cons-list">14.1. Conses as Lists   sec_14-1-2</a></span></dt><dd><dl><dt><span class="section"><a href="#map-func">14.1.1. Mapping Functions</a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="#arrays">15. Arrays chap-15</a></span></dt><dd><dl><dt><span class="section"><a href="#array-elts">15.1. Array Elements   sec_15-1-1</a></span></dt></dl></dd><dt><span class="chapter"><a href="#strings">16. Strings chap-16</a></span></dt><dd><dl><dt><span class="section"><a href="#string-misc">16.1. Miscellaneous</a></span></dt><dd><dl><dt><span class="section"><a href="#string-comp">16.1.1. String Comparison</a></span></dt><dt><span class="section"><a href="#string-width">16.1.2. Function <code class="function">EXT:STRING-WIDTH</code></a></span></dt><dt><span class="section"><a href="#string-invertcase">16.1.3. Functions <code class="function">EXT:STRING-INVERTCASE</code>   and <code class="function">EXT:NSTRING-INVERTCASE</code></a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="#sequences">17. Sequences   chap-17</a></span></dt><dd><dl><dt><span class="section"><a href="#seq-func-ext">17.1. Additional Functions</a></span></dt><dd><dl><dt><span class="section"><a href="#trim-if">17.1.1. Function <code class="function">EXT:TRIM-IF</code></a></span></dt></dl></dd><dt><span class="section"><a href="#seq-macro-ext">17.2. Additional Macros</a></span></dt><dd><dl><dt><span class="section"><a href="#doseq">17.2.1. Macro <code class="function">EXT:DOSEQ</code></a></span></dt></dl></dd><dt><span class="section"><a href="#nreverse-nreconc">17.3. Functions <code class="function">NREVERSE</code> &amp; <code class="function">NRECONC</code></a></span></dt><dt><span class="section"><a href="#rem-del">17.4. Functions <code class="function">REMOVE</code> &amp; <code class="function">DELETE</code></a></span></dt><dt><span class="section"><a href="#sorting">17.5. Functions <code class="function">SORT</code> &amp; <code class="function">STABLE-SORT</code></a></span></dt></dl></dd><dt><span class="chapter"><a href="#hash">18. Hash Tables chap-18</a></span></dt><dd><dl><dt><span class="section"><a href="#hash-mod-key">18.1. Modifying Hash Table Keys   sec_18-1-2</a></span></dt><dt><span class="section"><a href="#make-hash">18.2. Function <code class="function">MAKE-HASH-TABLE</code></a></span></dt><dd><dl><dt><span class="section"><a href="#hashtable-gc-rehash">18.2.1. Interaction between <code class="classname">HASH-TABLE</code>s and garbage-collection</a></span></dt></dl></dd><dt><span class="section"><a href="#defhash">18.3. Macro <code class="function">EXT:DEFINE-HASH-TABLE-TEST</code></a></span></dt><dt><span class="section"><a href="#ht-test">18.4. Function <code class="function">HASH-TABLE-TEST</code></a></span></dt><dt><span class="section"><a href="#dohash">18.5. Macro <code class="function">EXT:DOHASH</code></a></span></dt></dl></dd><dt><span class="chapter"><a href="#filenames">19. Filenames   chap-19</a></span></dt><dd><dl><dt><span class="section"><a href="#path-components">19.1. Pathname Components   sec_19-2-1</a></span></dt><dd><dl><dt><span class="section"><a href="#path-dir-canon">19.1.1. Directory canonicalization</a></span></dt><dt><span class="section"><a href="#path-platform-specific">19.1.2. Platform-specific issues</a></span></dt></dl></dd><dt><span class="section"><a href="#unspecific">19.2. :UNSPECIFIC as a Component Value  sec_19-2-2-2-3</a></span></dt><dt><span class="section"><a href="#path-external-notation">19.3. External notation</a></span></dt><dt><span class="section"><a href="#log-path">19.4. Logical Pathnames   sec_19-3</a></span></dt><dt><span class="section"><a href="#filename-misc">19.5. Miscellaneous</a></span></dt><dd><dl><dt><span class="section"><a href="#translate-pathname">19.5.1. Function <code class="function">TRANSLATE-PATHNAME</code></a></span></dt><dt><span class="section"><a href="#translate-logpath">19.5.2. Function <code class="function">TRANSLATE-LOGICAL-PATHNAME</code></a></span></dt><dt><span class="section"><a href="#parsename">19.5.3. Function <code class="function">PARSE-NAMESTRING</code></a></span></dt><dt><span class="section"><a href="#pathmerge">19.5.4. Function <code class="function">MERGE-PATHNAMES</code></a></span></dt><dt><span class="section"><a href="#load-lpt">19.5.5. Function <code class="function">LOAD-LOGICAL-PATHNAME-TRANSLATIONS</code></a></span></dt><dt><span class="section"><a href="#absolute-pathname">19.5.6. Function <code class="function">EXT:ABSOLUTE-PATHNAME</code></a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="#files">20. Files chap-20</a></span></dt><dd><dl><dt><span class="section"><a href="#dir-is-not-file">20.1. Directory is <span class="strong"><strong>not</strong></span> a file</a></span></dt><dd><dl><dt><span class="section"><a href="#probe-path">20.1.1. Function <code class="function">EXT:PROBE-PATHNAME</code></a></span></dt></dl></dd><dt><span class="section"><a href="#file-func">20.2. File functions</a></span></dt><dd><dl><dt><span class="section"><a href="#probe-file">20.2.1. Function <code class="function">PROBE-FILE</code></a></span></dt><dt><span class="section"><a href="#file-author">20.2.2. Function <code class="function">FILE-AUTHOR</code></a></span></dt><dt><span class="section"><a href="#del-file">20.2.3. Function <code class="function">DELETE-FILE</code></a></span></dt><dt><span class="section"><a href="#rename-file">20.2.4. Function <code class="function">RENAME-FILE</code></a></span></dt></dl></dd><dt><span class="section"><a href="#dir-func">20.3. Directory functions</a></span></dt><dd><dl><dt><span class="section"><a href="#probe-dir">20.3.1. Function <code class="function">EXT:PROBE-DIRECTORY</code></a></span></dt><dt><span class="section"><a href="#directory">20.3.2. Function <code class="function">DIRECTORY</code></a></span></dt><dt><span class="section"><a href="#dir">20.3.3. Function <code class="function">EXT:DIR</code></a></span></dt><dt><span class="section"><a href="#cd">20.3.4. Function <code class="function">EXT:CD</code></a></span></dt><dt><span class="section"><a href="#default-dir">20.3.5. Function <code class="function">EXT:DEFAULT-DIRECTORY</code></a></span></dt><dt><span class="section"><a href="#make-dir">20.3.6. Function <code class="function">EXT:MAKE-DIRECTORY</code></a></span></dt><dt><span class="section"><a href="#delete-dir">20.3.7. Function <code class="function">EXT:DELETE-DIRECTORY</code></a></span></dt><dt><span class="section"><a href="#rename-dir">20.3.8. Function <code class="function">EXT:RENAME-DIRECTORY</code></a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="#streams">21. Streams chap-21</a></span></dt><dd><dl><dt><span class="section"><a href="#streams-interactive">21.1. Interactive Streams  sec_21-1-1-1-3</a></span></dt><dd><dl><dt><span class="section"><a href="#stream-stdio-init">21.1.1. Initialization of Standard Streams</a></span></dt></dl></dd><dt><span class="section"><a href="#terminal">21.2. Terminal interaction</a></span></dt><dd><dl><dt><span class="section"><a href="#readline">21.2.1. Command line editing with GNU readline</a></span></dt><dt><span class="section"><a href="#with-kbd">21.2.2. Macro <code class="function">EXT:WITH-KEYBOARD</code></a></span></dt></dl></dd><dt><span class="section"><a href="#bin-io">21.3. Binary Input and Output</a></span></dt><dd><dl><dt><span class="section"><a href="#bin-input">21.3.1. Binary input, <code class="function">READ-BYTE</code>,   <code class="function">EXT:READ-INTEGER</code> &amp; <code class="function">EXT:READ-FLOAT</code></a></span></dt><dt><span class="section"><a href="#bin-output">21.3.2. Binary output, <code class="function">WRITE-BYTE</code>,   <code class="function">EXT:WRITE-INTEGER</code> &amp; <code class="function">EXT:WRITE-FLOAT</code></a></span></dt></dl></dd><dt><span class="section"><a href="#bulk-io">21.4. Bulk Input and Output</a></span></dt><dd><dl><dt><span class="section"><a href="#read-seq">21.4.1. Bulk Input</a></span></dt><dt><span class="section"><a href="#write-seq">21.4.2. Bulk Output</a></span></dt><dt><span class="section"><a href="#bulk-io-rationale">21.4.3. Rationale</a></span></dt></dl></dd><dt><span class="section"><a href="#non-block-io">21.5. Non-Blocking Input and Output</a></span></dt><dt><span class="section"><a href="#newline-convention">21.6. Newline Convention</a></span></dt><dd><dl><dt><span class="section"><a href="#nl-question">21.6.1. Should programs output a newline before   or after each line of output?</a></span></dt><dt><span class="section"><a href="#nl-trad-analysis">21.6.2. Analysis</a></span></dt><dt><span class="section"><a href="#nl-conclusion">21.6.3. Conclusion</a></span></dt><dt><span class="section"><a href="#nl-solution">21.6.4. Solution</a></span></dt><dt><span class="section"><a href="#nl-elnl-analysis">21.6.5. Elastic Newline Analysis</a></span></dt></dl></dd><dt><span class="section"><a href="#stream-extfmt">21.7. Function <code class="function">STREAM-EXTERNAL-FORMAT</code></a></span></dt><dt><span class="section"><a href="#stream-eltype">21.8. Function <code class="function">STREAM-ELEMENT-TYPE</code></a></span></dt><dd><dl><dt><span class="section"><a href="#bin-stdio">21.8.1. Binary input from <code class="varname">*STANDARD-INPUT*</code></a></span></dt></dl></dd><dt><span class="section"><a href="#make-stream">21.9. Function <code class="function">EXT:MAKE-STREAM</code></a></span></dt><dt><span class="section"><a href="#file-pos">21.10. Function <code class="function">FILE-POSITION</code></a></span></dt><dt><span class="section"><a href="#elastic-newline">21.11. Function <code class="function">EXT:ELASTIC-NEWLINE</code></a></span></dt><dt><span class="section"><a href="#open">21.12. Function <code class="function">OPEN</code></a></span></dt><dt><span class="section"><a href="#clear-input">21.13. Function <code class="function">CLEAR-INPUT</code></a></span></dt><dt><span class="section"><a href="#close">21.14. Function <code class="function">CLOSE</code></a></span></dt><dt><span class="section"><a href="#open-stream-p">21.15. Function <code class="function">OPEN-STREAM-P</code></a></span></dt><dt><span class="section"><a href="#broadcast-stream">21.16. Class <code class="classname">BROADCAST-STREAM</code></a></span></dt><dt><span class="section"><a href="#stream-buffer">21.17. Functions   <code class="function">EXT:MAKE-BUFFERED-INPUT-STREAM</code>
    and   <code class="function">EXT:MAKE-BUFFERED-OUTPUT-STREAM</code>
     </a></span></dt><dt><span class="section"><a href="#stream-handles">21.18. Function   <code class="function">EXT:STREAM-HANDLES</code></a></span></dt></dl></dd><dt><span class="chapter"><a href="#printer">22. Printer chap-22</a></span></dt><dd><dl><dt><span class="section"><a href="#multi-rep">22.1. Multiple Possible Textual Representations   sec_22-1-1-1</a></span></dt><dt><span class="section"><a href="#write-float-decimal">22.2. Printing Floats   sec_22-1-3-1-3</a></span></dt><dt><span class="section"><a href="#spacecharprint">22.3. Printing Characters   sec_22-1-3-2</a></span></dt><dt><span class="section"><a href="#sym-pack-prefix">22.4. Package Prefixes for Symbols   sec_22-1-3-3-1</a></span></dt><dt><span class="section"><a href="#print-vector">22.5. Printing Other Vectors   sec_22-1-3-7</a></span></dt><dt><span class="section"><a href="#print-array">22.6. Printing Other Arrays   sec_22-1-3-8</a></span></dt><dd><dl><dt><span class="section"><a href="#pathprint">22.6.1. Printing Pathnames   sec_22-1-3-11</a></span></dt></dl></dd><dt><span class="section"><a href="#clpp">22.7. The Lisp Pretty Printer   sec_22-2</a></span></dt><dd><dl><dt><span class="section"><a href="#pp-dispatch">22.7.1. Pretty Print Dispatch Table   sec_22-2-1-4</a></span></dt></dl></dd><dt><span class="section"><a href="#print-formatted">22.8. Formatted Output   sec_22-3</a></span></dt><dt><span class="section"><a href="#write">22.9. Functions <code class="function">WRITE</code> &amp; <code class="function">WRITE-TO-STRING</code></a></span></dt><dt><span class="section"><a href="#print-unreadable-object">22.10. Macro <code class="function">PRINT-UNREADABLE-OBJECT</code></a></span></dt><dt><span class="section"><a href="#print-misc">22.11. Miscellaneous Issues</a></span></dt></dl></dd><dt><span class="chapter"><a href="#reader">23. Reader chap-23</a></span></dt><dd><dl><dt><span class="section"><a href="#rt-case">23.1. Effect of Readtable Case on the Lisp Reader   sec_23-1-2</a></span></dt><dt><span class="section"><a href="#recursive-p">23.2. The <em class="replaceable"><code>recursive-p</code></em> argument   sec_23-1-3-2</a></span></dt></dl></dd><dt><span class="chapter"><a href="#system">24. System Construction   chap-24</a></span></dt><dd><dl><dt><span class="section"><a href="#compilefile">24.1. Function <code class="function">COMPILE-FILE</code></a></span></dt><dd><dl><dt><span class="section"><a href="#compile-file-output">24.1.1. Output files</a></span></dt><dt><span class="section"><a href="#compile-file-return">24.1.2. Return values</a></span></dt></dl></dd><dt><span class="section"><a href="#compile-file-path">24.2. Function <code class="function">COMPILE-FILE-PATHNAME</code></a></span></dt><dt><span class="section"><a href="#require">24.3. Function <code class="function">REQUIRE</code></a></span></dt><dd><dl><dt><span class="section"><a href="#require-return">24.3.1. Return value</a></span></dt><dt><span class="section"><a href="#require-search">24.3.2. Additional <code class="function">LOAD</code> locations</a></span></dt><dt><span class="section"><a href="#module-providers">24.3.3. User variable <code class="varname">CUSTOM::*MODULE-PROVIDER-FUNCTIONS*</code></a></span></dt><dt><span class="section"><a href="#lib-files">24.3.4. Interaction with <code class="function">COMPILE-FILE</code></a></span></dt></dl></dd><dt><span class="section"><a href="#loadfile">24.4. Function <code class="function">LOAD</code></a></span></dt><dt><span class="section"><a href="#features">24.5. Variable <code class="varname">*FEATURES*</code></a></span></dt><dt><span class="section"><a href="#featurep">24.6. Function <code class="function">EXT:FEATUREP</code>   [CLRFI-1]</a></span></dt><dt><span class="section"><a href="#compiled-file-p">24.7. Function <code class="function">EXT:COMPILED-FILE-P</code>   [CLRFI-2]</a></span></dt></dl></dd><dt><span class="chapter"><a href="#environment">25. Environment   chap-25</a></span></dt><dd><dl><dt><span class="section"><a href="#repl">25.1. Top Level Loop   sec_25-1-1</a></span></dt><dd><dl><dt><span class="section"><a href="#user-commands">25.1.1. User-defined Commands</a></span></dt></dl></dd><dt><span class="section"><a href="#debugger">25.2. Debugging Utilities   sec_25-1-2</a></span></dt><dd><dl><dt><span class="section"><a href="#disassemble">25.2.1. Function <code class="function">DISASSEMBLE</code></a></span></dt><dt><span class="section"><a href="#uncompile">25.2.2. Function <code class="function">EXT:UNCOMPILE</code></a></span></dt><dt><span class="section"><a href="#show-stack">25.2.3. Function <code class="function">EXT:SHOW-STACK</code></a></span></dt><dt><span class="section"><a href="#documentation">25.2.4. Function <code class="function">DOCUMENTATION</code></a></span></dt><dt><span class="section"><a href="#describe">25.2.5. Function <code class="function">DESCRIBE</code></a></span></dt><dt><span class="section"><a href="#trace">25.2.6. Macro <code class="function">TRACE</code></a></span></dt><dt><span class="section"><a href="#inspect">25.2.7. Function <code class="function">INSPECT</code></a></span></dt><dt><span class="section"><a href="#time">25.2.8. Macro <code class="function">TIME</code></a></span></dt><dt><span class="section"><a href="#ed">25.2.9. Function <code class="function">ED</code></a></span></dt><dt><span class="section"><a href="#apropos">25.2.10. Functions <code class="function">APROPOS</code> &amp; <code class="function">APROPOS-LIST</code></a></span></dt><dt><span class="section"><a href="#dribble">25.2.11. Function <code class="function">DRIBBLE</code></a></span></dt></dl></dd><dt><span class="section"><a href="#environment-enq">25.3. Environment Inquiry   sec_25-1-3</a></span></dt><dd><dl><dt><span class="section"><a href="#room">25.3.1. Function <code class="function">ROOM</code></a></span></dt><dt><span class="section"><a href="#gc-sect">25.3.2. Function <code class="function">EXT:GC</code>
   </a></span></dt><dt><span class="section"><a href="#machine">25.3.3. Machine</a></span></dt><dt><span class="section"><a href="#version">25.3.4. Function <code class="function">LISP-IMPLEMENTATION-VERSION</code></a></span></dt><dt><span class="section"><a href="#argv">25.3.5. Function <code class="function">EXT:ARGV</code></a></span></dt></dl></dd><dt><span class="section"><a href="#clock">25.4. Time sec_25-1-4</a></span></dt></dl></dd><dt><span class="chapter"><a href="#glossary">26. Glossary   chap-26</a></span></dt><dt><span class="chapter"><a href="#appendix">27. Appendix   chap-a</a></span></dt><dt><span class="chapter"><a href="#issues">28. X3J13 Issue Index    [CLHS-ic]</a></span></dt></dl></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="intro"></a>Chapter 1. Introduction
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-1.html">[chap-1]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#spec-symb">1.1. Special Symbols   sec_1-4-1-3</a></span></dt><dt><span class="section"><a href="#error-terms">1.2. Error Terminology   sec_1-4-2</a></span></dt><dt><span class="section"><a href="#cl-symb">1.3. Symbols in the Package <strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong>   sec_1-9</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="spec-symb"></a>1.1. Special Symbols
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_1-4-1-3.html">[sec_1-4-1-3]</a></h2></div></div></div><p>The <strong class="first"><em class="firstterm">final delimiter
  <a id="fin-delim" class="indexterm"></a></em></strong>
 of an interactive stream:
 </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a></span></dt><dd>type <span class="keycap"><strong>Control</strong></span>+<span class="keysym">D</span>
     at the beginning of a line</dd><dt><span class="term"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a></span></dt><dd>type <span class="keycap"><strong>Control</strong></span>+<span class="keysym">Z</span>,
     followed by <span class="keycap"><strong>Enter</strong></span></dd></dl></div><p>
 This final delimiter is never actually seen by programs; no need to
 test for <span class="keysym">#\^D</span> or <span class="keysym">#\^Z</span> - use
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-char-no-hang.html" target="_top"><code class="function">READ-CHAR-NO-HANG</code></a> to check for <code class="literal"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#end-of-stream">end-of-stream</a></code>.</p><p>A newline character can be entered by the user by pressing the
 <span class="keycap"><strong>Enter</strong></span> key.</p><p>See also <a class="xref" href="#clear-input" title="21.13. Function CLEAR-INPUT">Section 21.13, “Function <code class="function">CLEAR-INPUT</code>”</a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="error-terms"></a>1.2. Error Terminology
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_1-4-2.html">[sec_1-4-2]</a></h2></div></div></div><p>Safety settings are ignored by the interpreted code;
 therefore where the standard uses the phrase <span class="quote">“<span class="quote">should signal an
 error</span>”</span>, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.
 See <a class="xref" href="#safety-decl" title="3.3.5. Declaration SAFETY">Section 3.3.5, “Declaration <code class="literal">SAFETY</code>”</a> for the safety of compiled code.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="cl-symb"></a>1.3. Symbols in the Package <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong></a>
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_1-9.html">[sec_1-9]</a></h2></div></div></div><p>All 978 symbols in the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong></a> package specified by the
 [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] are implemented.</p></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="syntax"></a>Chapter 2. Syntax <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-2.html">[chap-2]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#std-char">2.1. Standard Characters   sec_2-1-3</a></span></dt><dt><span class="section"><a href="#reader-alg">2.2. Reader Algorithm   sec_2-2</a></span></dt><dt><span class="section"><a href="#tokens">2.3. Symbols as Tokens   sec_2-3-4</a></span></dt><dt><span class="section"><a href="#valid-patterns">2.4. Valid Patterns for Tokens   sec_2-3-5</a></span></dt><dt><span class="section"><a href="#backquote">2.5. Backquote   sec_2-4-6</a></span></dt><dt><span class="section"><a href="#sharpsign">2.6. Sharpsign   sec_2-4-8</a></span></dt><dd><dl><dt><span class="section"><a href="#sharpsign-backslash">2.6.1. Sharpsign Backslash   sec_2-4-8-1</a></span></dt><dt><span class="section"><a href="#sharpsign-less-than">2.6.2. Sharpsign Less-Than-Sign   sec_2-4-8-20</a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="std-char"></a>2.1. Standard Characters
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-1-3.html">[sec_2-1-3]</a></h2></div></div></div><p>The standard characters are <span class="keysym">#\Newline</span> and the
 <a class="link" href="#graph-char" title="13.5. Graphic Characters sec_13-1-4-1">graphic characters</a>
 with a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> between 32 and 126 (inclusive).</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="reader-alg"></a>2.2. Reader Algorithm
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-2.html">[sec_2-2]</a></h2></div></div></div><p>The requirement of step 4 that a <span class="quote">“<span class="quote"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_r.html#reader_macro_function">reader
   macro function</a> may return zero values or one value</span>”</span>
 <span class="strong"><strong>is</strong></span> enforced.  You can use the function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_values.html" target="_top"><code class="function">VALUES</code></a> to control the
 number of values returned.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="tokens"></a>2.3. Symbols as Tokens
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-3-4.html">[sec_2-3-4]</a></h2></div></div></div><p>A <strong class="first"><em class="firstterm">reserved token
  <a id="res-token" class="indexterm"></a></em></strong>,
 i.e., a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_t.html#token">token</a> that has
 <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#potential_number">potential number</a> syntax but cannot be
 interpreted as a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_number.html" target="_top"><code class="classname">NUMBER</code></a>, is interpreted as <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a> when being
 read.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="valid-patterns"></a>2.4. Valid Patterns for Tokens
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-3-5.html">[sec_2-3-5]</a></h2></div></div></div><p>When a token with package markers is read, then no checking is
 done whether the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_symbol-package.html" target="_top"><code class="function">SYMBOL-PACKAGE</code></a> part and the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_symbol-name.html" target="_top"><code class="function">SYMBOL-NAME</code></a> part do
 not have number syntax. (What would the purpose of this check be?)
 So we consider tokens like <span class="token">USER::</span> or <span class="token">:1</span> or
 <span class="token">LISP::4711</span> or <span class="token">21:3</span> as symbols.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="backquote"></a>2.5. Backquote
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-6.html">[sec_2-4-6]</a></h2></div></div></div><p>The backquote read macro also works when nested. Example:
<a id="bq-nested"></a></p><pre class="programlisting">
   (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eval.html" target="_top"><code class="function">EVAL</code></a> ``(,#'(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_lambda.html" target="_top"><code class="function">LAMBDA</code></a> () ',a) ,#'(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_lambda.html" target="_top"><code class="function">LAMBDA</code></a> () ',b)))
 ≡ (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eval.html" target="_top"><code class="function">EVAL</code></a> `(list #'(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_lambda.html" target="_top"><code class="function">LAMBDA</code></a> () ',a) #'(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_lambda.html" target="_top"><code class="function">LAMBDA</code></a> () ',b)))
 ≡ (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eval.html" target="_top"><code class="function">EVAL</code></a> (list 'list (list 'function (list 'lambda nil (list 'quote a)))
                     (list 'function (list 'lambda nil (list 'quote b)))))
</pre></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="sharpsign"></a>2.6. Sharpsign
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8.html">[sec_2-4-8]</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#sharpsign-backslash">2.6.1. Sharpsign Backslash   sec_2-4-8-1</a></span></dt><dt><span class="section"><a href="#sharpsign-less-than">2.6.2. Sharpsign Less-Than-Sign   sec_2-4-8-20</a></span></dt></dl></div><p>Reader macros are also defined for the following:
</p><div class="variablelist"><a id="extra-read-macro-table"></a><p class="title"><strong>Additional reader macros</strong></p><dl class="variablelist"><dt><span class="term"><span class="data"><code class="literal">#,</code></span></span></dt><dd>load-time evaluation, kept despite the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>]
    issue <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss315.html" target="_top">SHARP-COMMA-CONFUSION:REMOVE</a>.</dd><dt><span class="term"><span class="data"><code class="literal">#Y</code></span></span></dt><dd>compiled <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a> objects and <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_i.html#input">input</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>'s <a class="link" href="#encoding" title="31.5. Encodings"><code class="classname">EXT:ENCODING</code></a>s
 </dd><dt><span class="term"><span class="data"><code class="literal">#""</code></span></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_pathname.html" target="_top"><code class="classname">PATHNAME</code></a>: <code class="filename">#"test.lisp"</code>
   is the value of <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_pathname.html" target="_top"><code class="function">PATHNAME</code></a> "test.lisp")</code></dd></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="sharpsign-backslash"></a>2.6.1. Sharpsign Backslash
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-1.html">[sec_2-4-8-1]</a></h3></div></div></div><p><span class="keysym">#\Code</span> allows input of characters of arbitrary code:
 e.g., <span class="keysym">#\Code231</span> reads as the character
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> 231)</code>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="sharpsign-less-than"></a>2.6.2. Sharpsign Less-Than-Sign
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">[sec_2-4-8-20]</a></h3></div></div></div><p>This is the list of objects whose external representation cannot
 be meaningfully read in:</p><div class="variablelist"><a id="unreadable-objects"></a><p class="title"><strong>Unreadable objects</strong></p><dl class="variablelist"><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a><em class="replaceable"><code>type</code></em> ...&gt;</code></span></span></dt><dd>all <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_structure-object.html" target="_top"><code class="classname">STRUCTURE-OBJECT</code></a>s lacking a keyword
   constructor</dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>ARRAY <em class="replaceable"><code>type</code></em>
   <em class="replaceable"><code>dimensions</code></em>&gt;</code></span></span></dt><dd>all <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_array.html" target="_top"><code class="classname">ARRAY</code></a>s except <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>s, if
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-arrayst.html" target="_top"><code class="varname">*PRINT-ARRAY*</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>SYSTEM-FUNCTION <em class="replaceable"><code>name</code></em>&gt;</code></span></span></dt><dd>built-in function written in <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>
</dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>ADD-ON-SYSTEM-FUNCTION
   <em class="replaceable"><code>name</code></em>&gt;</code></span></span></dt><dd><a href="impnotes.html#modules" class="olink">module</a> function written in <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>
</dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>SPECIAL-OPERATOR
   <em class="replaceable"><code>name</code></em>&gt;</code></span></span></dt><dd>special operator handler</dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>COMPILED-FUNCTION
   <em class="replaceable"><code>name</code></em>&gt;</code></span></span></dt><dd>compiled function, if <a class="link" href="#pr-closure" title="Variable CUSTOM:*PRINT-CLOSURE*"><code class="varname">CUSTOM:*PRINT-CLOSURE*</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
</dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>FUNCTION <em class="replaceable"><code>name</code></em> ...&gt;</code></span></span></dt><dd>interpreted function, , if <a class="link" href="#pr-closure" title="Variable CUSTOM:*PRINT-CLOSURE*"><code class="varname">CUSTOM:*PRINT-CLOSURE*</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
</dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>FRAME-POINTER #x...&gt;</code></span></span></dt><dd>pointer to a stack frame</dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>DISABLED POINTER&gt;</code></span></span></dt><dd>frame pointer which has become invalid on exit from the
   corresponding <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_block.html" target="_top"><code class="function">BLOCK</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_tagbody.html" target="_top"><code class="function">TAGBODY</code></a></dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>...STREAM...&gt;</code></span></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a></dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>PACKAGE <em class="replaceable"><code>name</code></em>&gt;</code></span></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_package.html" target="_top"><code class="classname">PACKAGE</code></a></dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>HASH-TABLE #x...&gt;</code></span></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a>, if <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-arrayst.html" target="_top"><code class="varname">*PRINT-ARRAY*</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
</dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>READTABLE #x...&gt;</code></span></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_readtable.html" target="_top"><code class="classname">READTABLE</code></a></dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>SYMBOL-MACRO <em class="replaceable"><code>form</code></em>&gt;</code></span></span></dt><dd><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-symbol-macro.html"><code class="classname">SYMBOL-MACRO</code></a> handler</dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>MACRO <em class="replaceable"><code>function</code></em>&gt;</code></span></span></dt><dd>macro expander (defined by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmacro.html" target="_top"><code class="function">DEFMACRO</code></a> and friends)
</dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a><a class="link" href="#fptr"><code class="classname">FFI:FOREIGN-POINTER</code></a>
   #x...&gt;</code></span></span></dt><dd>foreign pointer (<span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platforms only.</span></span>)
</dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a><a class="link" href="#faddr"><code class="classname">FFI:FOREIGN-ADDRESS</code></a>
   #x...&gt;</code></span></span></dt><dd>foreign address
   (<span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platforms only.</span></span>)</dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a><a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a> <em class="replaceable"><code>name</code></em>
   #x...&gt;</code></span></span></dt><dd>foreign variable (<span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platforms only.</span></span>)
</dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a><a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a> <em class="replaceable"><code>name</code></em>
   #x...&gt;</code></span></span></dt><dd>foreign function (<span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platforms only.</span></span>)
</dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>UNBOUND&gt;</code></span></span></dt><dd><span class="quote">“<span class="quote">value</span>”</span> of an unbound symbol, an unsupplied
   optional or keyword argument</dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>SPECIAL REFERENCE&gt;</code></span></span></dt><dd>environment marker for variables declared <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_special.html" target="_top"><code class="literal">SPECIAL</code></a>
</dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>DOT&gt;</code></span></span></dt><dd>internal <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_readcm_re_g-whitespace.html" target="_top"><code class="function">READ</code></a> result for <span class="quote">“<span class="quote">.</span>”</span>
</dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>END OF FILE&gt;</code></span></span></dt><dd>internal <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_readcm_re_g-whitespace.html" target="_top"><code class="function">READ</code></a> result, when the <code class="literal"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#end-of-stream">end-of-stream</a></code> is reached
</dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>READ-LABEL ...&gt;</code></span></span></dt><dd>intermediate <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_readcm_re_g-whitespace.html" target="_top"><code class="function">READ</code></a> result for <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-16.html"><span class="data"><code class="literal">#n#</code></span></a>
</dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>ADDRESS #x...&gt;</code></span></span></dt><dd>machine address, should not occur
</dd><dt><span class="term"><span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>SYSTEM-POINTER #x...&gt;</code></span></span></dt><dd>should not occur</dd></dl></div></div></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="eval"></a>Chapter 3. Evaluation and Compilation
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-3.html">[chap-3]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#evaluation">3.1. Evaluation   sec_3-1</a></span></dt><dd><dl><dt><span class="section"><a href="#eval-environ">3.1.1. Introduction to Environments   sec_3-1-1</a></span></dt><dt><span class="section"><a href="#sym-forms">3.1.2. Symbols as Forms   sec_3-1-2-1-1</a></span></dt><dd><dl><dt><span class="section"><a href="#def-sym-mac">3.1.2.1. Macro <code class="function">DEFINE-SYMBOL-MACRO</code></a></span></dt><dt><span class="section"><a href="#dyn-var">3.1.2.2. Dynamic Variables   sec_3-1-2-1-1-2</a></span></dt></dl></dd><dt><span class="section"><a href="#cons-forms">3.1.3. Conses as Forms   sec_3-1-2-1-2</a></span></dt><dt><span class="section"><a href="#specforms">3.1.4. Special Forms   sec_3-1-2-1-2-1</a></span></dt><dd><dl><dt><span class="section"><a href="#eval-when">3.1.4.1. Special operator <code class="function">EVAL-WHEN</code></a></span></dt><dt><span class="section"><a href="#speop-the">3.1.4.2. Special operator <code class="function">THE</code></a></span></dt></dl></dd><dt><span class="section"><a href="#funforms">3.1.5. Function Forms   sec_3-1-2-1-2-3</a></span></dt><dd><dl><dt><span class="section"><a href="#sym-fun">3.1.5.1. Function <code class="function">SYMBOL-FUNCTION</code></a></span></dt></dl></dd><dt><span class="section"><a href="#defun">3.1.6. Macros <code class="function">DEFUN</code> &amp; <code class="function">DEFMACRO</code></a></span></dt></dl></dd><dt><span class="section"><a href="#compilation">3.2. Compilation   sec_3-2</a></span></dt><dd><dl><dt><span class="section"><a href="#compiler-terms">3.2.1. Compiler Terminology   sec_3-2-1</a></span></dt><dd><dl><dt><span class="section"><a href="#compile-jit">3.2.1.1. Just-In-Time Native Compilation</a></span></dt></dl></dd><dt><span class="section"><a href="#compilation-semantics">3.2.2. Compilation Semantics   sec_3-2-2</a></span></dt><dd><dl><dt><span class="section"><a href="#compiler-macros">3.2.2.1. Compiler Macros   sec_3-2-2-1</a></span></dt><dt><span class="section"><a href="#minimal-compilation">3.2.2.2. Minimal Compilation   sec_3-2-2-2</a></span></dt><dt><span class="section"><a href="#semantic-constraints">3.2.2.3. Semantic Constraints   sec_3-2-2-3</a></span></dt></dl></dd><dt><span class="section"><a href="#similarity">3.2.3. Definition of Similarity   sec_3-2-4-2-2</a></span></dt><dt><span class="section"><a href="#compile-errors">3.2.4. Exceptional Situations in the Compiler   sec_3-2-5</a></span></dt></dl></dd><dt><span class="section"><a href="#declarations">3.3. Declarations   sec_3-3</a></span></dt><dd><dl><dt><span class="section"><a href="#decl-min">3.3.1. Minimal Declaration Processing Requirements   sec_3-3-1</a></span></dt><dt><span class="section"><a href="#spec-decl">3.3.2. Declaration <code class="literal">SPECIAL</code></a></span></dt><dt><span class="section"><a href="#constant-notinline">3.3.3. Declaration <code class="literal">EXT:CONSTANT-NOTINLINE</code></a></span></dt><dt><span class="section"><a href="#constantp">3.3.4. Function <code class="function">CONSTANTP</code></a></span></dt><dt><span class="section"><a href="#safety-decl">3.3.5. Declaration <code class="literal">SAFETY</code></a></span></dt><dt><span class="section"><a href="#compile-decl">3.3.6. Declaration <code class="code">(COMPILE)</code></a></span></dt><dt><span class="section"><a href="#space-decl">3.3.7. Declaration <code class="literal">SPACE</code></a></span></dt></dl></dd><dt><span class="section"><a href="#lalist">3.4. Lambda Lists   sec_3-4</a></span></dt><dd><dl><dt><span class="section"><a href="#boa-lalist">3.4.1. Boa Lambda Lists   sec_3-4-6</a></span></dt></dl></dd></dl></div><p>All the functions built by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_function.html" target="_top"><code class="function">FUNCTION</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile.html" target="_top"><code class="function">COMPILE</code></a> and the like are
 atoms.  There are built-in functions written in <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>, compiled
 functions (both of type <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_compiled-function.html" target="_top"><code class="classname">COMPILED-FUNCTION</code></a>) and interpreted
 functions (of type <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a>).</p><div class="table"><a id="eval-limits-table"></a><p class="title"><strong>Table 3.1. Function call limits</strong></p><div class="table-contents"><table class="table" summary="Function call limits" border="1"><colgroup><col /><col /></colgroup><tbody><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_call-a_uments-limit.html" target="_top"><code class="constant">CALL-ARGUMENTS-LIMIT</code></a></td><td align="center">2<sup>12</sup>=4096</td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_multip_values-limit.html" target="_top"><code class="constant">MULTIPLE-VALUES-LIMIT</code></a></td><td align="center">2<sup>7</sup>=128</td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_lambda_meters-limit.html" target="_top"><code class="constant">LAMBDA-PARAMETERS-LIMIT</code></a></td><td align="center">2<sup>12</sup>=4096</td></tr></tbody></table></div></div><br class="table-break" /><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="evaluation"></a>3.1. Evaluation
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1.html">[sec_3-1]</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#eval-environ">3.1.1. Introduction to Environments   sec_3-1-1</a></span></dt><dt><span class="section"><a href="#sym-forms">3.1.2. Symbols as Forms   sec_3-1-2-1-1</a></span></dt><dd><dl><dt><span class="section"><a href="#def-sym-mac">3.1.2.1. Macro <code class="function">DEFINE-SYMBOL-MACRO</code></a></span></dt><dt><span class="section"><a href="#dyn-var">3.1.2.2. Dynamic Variables   sec_3-1-2-1-1-2</a></span></dt></dl></dd><dt><span class="section"><a href="#cons-forms">3.1.3. Conses as Forms   sec_3-1-2-1-2</a></span></dt><dt><span class="section"><a href="#specforms">3.1.4. Special Forms   sec_3-1-2-1-2-1</a></span></dt><dd><dl><dt><span class="section"><a href="#eval-when">3.1.4.1. Special operator <code class="function">EVAL-WHEN</code></a></span></dt><dt><span class="section"><a href="#speop-the">3.1.4.2. Special operator <code class="function">THE</code></a></span></dt></dl></dd><dt><span class="section"><a href="#funforms">3.1.5. Function Forms   sec_3-1-2-1-2-3</a></span></dt><dd><dl><dt><span class="section"><a href="#sym-fun">3.1.5.1. Function <code class="function">SYMBOL-FUNCTION</code></a></span></dt></dl></dd><dt><span class="section"><a href="#defun">3.1.6. Macros <code class="function">DEFUN</code> &amp; <code class="function">DEFMACRO</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="eval-environ"></a>3.1.1. Introduction to Environments
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1.html">[sec_3-1-1]</a></h3></div></div></div><p><a id="the-env"></a><strong>Macro <a class="link" href="#the-env" title="Macro EXT:THE-ENVIRONMENT"><code class="function">EXT:THE-ENVIRONMENT</code></a>. </strong>As in Scheme, the macro <code class="code">(<a class="link" href="#the-env" title="Macro EXT:THE-ENVIRONMENT"><code class="function">EXT:THE-ENVIRONMENT</code></a>)</code>
 returns the current <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a>.  This works only in interpreted code and
 is not compilable!</p><p><a id="eval-env"></a><strong>Function <code class="code">(EXT:EVAL-ENV
 <em class="replaceable"><code>form</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-4.html">environment</a></code></em>)</code>. </strong>evaluates a form in a given <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a>, just as if the
 form had been a part of the program that the <em class="replaceable"><code><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-4.html">environment</a></code></em> came from.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="sym-forms"></a>3.1.2. Symbols as Forms
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-1.html">[sec_3-1-2-1-1]</a></h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#def-sym-mac">3.1.2.1. Macro <code class="function">DEFINE-SYMBOL-MACRO</code></a></span></dt><dt><span class="section"><a href="#dyn-var">3.1.2.2. Dynamic Variables   sec_3-1-2-1-1-2</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="def-sym-mac"></a>3.1.2.1. Macro <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-symbol-macro.html" target="_top"><code class="function">DEFINE-SYMBOL-MACRO</code></a></h4></div></div></div><p>The macro <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-symbol-macro.html" target="_top"><code class="function">DEFINE-SYMBOL-MACRO</code></a> establishes <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-symbol-macro.html"><code class="classname">SYMBOL-MACRO</code></a>s with
 global scope (as opposed to <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-symbol-macro.html"><code class="classname">SYMBOL-MACRO</code></a>s defined with
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_symbol-macrolet.html" target="_top"><code class="function">SYMBOL-MACROLET</code></a>, which have local scope).</p><p>The function
 <strong class="first"><em class="firstterm"><a class="link" href="#symbol-mex"><code class="function">EXT:SYMBOL-MACRO-EXPAND</code></a><a id="symbol-mex" class="indexterm"></a></em></strong>
 tests for a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-symbol-macro.html"><code class="classname">SYMBOL-MACRO</code></a>: If <em class="replaceable"><code>symbol</code></em> is defined as a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-symbol-macro.html"><code class="classname">SYMBOL-MACRO</code></a>
 in the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-1.html">global environment</a>, <code class="code">(<a class="link" href="#symbol-mex"><code class="function">EXT:SYMBOL-MACRO-EXPAND</code></a> <em class="replaceable"><code>symbol</code></em>)</code> returns two
 values, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> and the expansion; otherwise it returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</p><p><a class="link" href="#symbol-mex"><code class="function">EXT:SYMBOL-MACRO-EXPAND</code></a> is a special case of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_macroexpa_acroexpand-1.html" target="_top"><code class="function">MACROEXPAND-1</code></a>. <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_macroexpa_acroexpand-1.html" target="_top"><code class="function">MACROEXPAND-1</code></a>
 can also test whether a symbol is defined as a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-symbol-macro.html"><code class="classname">SYMBOL-MACRO</code></a> in <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a>s
 other than the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-1.html">global environment</a>.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="dyn-var"></a>3.1.2.2. Dynamic Variables
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-1-2.html">[sec_3-1-2-1-1-2]</a></h4></div></div></div><p><span class="quote">“<span class="quote">Undefined variables</span>”</span>, i.e. <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-1.html">variable</a>s which are
 referenced outside any lexical binding for a variable of the same name
 and which are not declared <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_special.html" target="_top"><code class="literal">SPECIAL</code></a>, are treated like <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-1-2.html">dynamic variable</a>s
 in the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-1.html">global environment</a>.  The compiler <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_warning.html" target="_top"><code class="classname">WARNING</code></a> when it
 encounters an undefined variable.</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="cons-forms"></a>3.1.3. Conses as Forms
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-2.html">[sec_3-1-2-1-2]</a></h3></div></div></div><p>Lists of the form <code class="code">((<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <em class="replaceable"><code>symbol</code></em>) ...)</code> are also
 treated as function forms. This makes the syntax
 <code class="code">(<em class="replaceable"><code>function-name</code></em> <em class="replaceable"><code>arguments</code></em> ...)</code> consistent with the syntax
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_funcall.html" target="_top"><code class="function">FUNCALL</code></a> #'<em class="replaceable"><code>function-name</code></em> <em class="replaceable"><code>arguments</code></em> ...)</code>.
 It implements the item 7 of the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] issue <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss174.html" target="_top">FUNCTION-NAME:LARGE</a> and the
 definition of <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_f.html#function_form">function form</a>s,
 and is consistent with the use of <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_f.html#function_name">function name</a>s elsewhere in <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a>.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="specforms"></a>3.1.4. Special Forms
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-2-1.html">[sec_3-1-2-1-2-1]</a></h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#eval-when">3.1.4.1. Special operator <code class="function">EVAL-WHEN</code></a></span></dt><dt><span class="section"><a href="#speop-the">3.1.4.2. Special operator <code class="function">THE</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="eval-when"></a>3.1.4.1. Special operator <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_eval-when.html" target="_top"><code class="function">EVAL-WHEN</code></a></h4></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_eval-when.html" target="_top"><code class="function">EVAL-WHEN</code></a> also accepts the situations <code class="code">(NOT EVAL)</code>
 and <code class="code">(NOT COMPILE)</code>.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>The situations <code class="constant">EVAL</code>,
 <code class="constant">LOAD</code> and <code class="constant">COMPILE</code> are
 deprecated by the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>], and they are <span class="strong"><strong>not</strong></span> equivalent to the new
 standard situations <code class="constant">:EXECUTE</code>,
 <code class="constant">:LOAD-TOPLEVEL</code>
 and <code class="constant">:COMPILE-TOPLEVEL</code> in that they ignore the
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-2-3-1.html">top-level form</a> versus non-<a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-2-3-1.html">top-level form</a> distinction.</p></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="speop-the"></a>3.1.4.2. Special operator <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_the.html" target="_top"><code class="function">THE</code></a></h4></div></div></div><p>The special form <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_the.html" target="_top"><code class="function">THE</code></a> <em class="replaceable"><code>value-type</code></em> <em class="replaceable"><code>form</code></em>)</code> is
 similar to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_check-type.html" target="_top"><code class="function">CHECK-TYPE</code></a> but does a type check only in interpreted
 code (no type check is done in compiled code - but see the <a class="link" href="#ethe" title="31.11.1. Macro EXT:ETHE"><code class="function">EXT:ETHE</code></a>
 macro) and does not allow interactive error correction by the user.
</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="funforms"></a>3.1.5. Function Forms
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-2-3.html">[sec_3-1-2-1-2-3]</a></h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#sym-fun">3.1.5.1. Function <code class="function">SYMBOL-FUNCTION</code></a></span></dt></dl></div><p><strong>Constant <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_lambda_ist-keywords.html" target="_top"><code class="constant">LAMBDA-LIST-KEYWORDS</code></a>. </strong><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;ALLOW-OTHER-KEYS</code></a>
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;AUX</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;WHOLE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;ENVIRONMENT</code></a>)</code></p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="sym-fun"></a>3.1.5.1. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_symbol-function.html" target="_top"><code class="function">SYMBOL-FUNCTION</code></a></h4></div></div></div><p><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_symbol-function.html" target="_top"><code class="function">SYMBOL-FUNCTION</code></a> <em class="replaceable"><code>symbol</code></em>) <em class="replaceable"><code>object</code></em>)</code>
 requires <em class="replaceable"><code>object</code></em> to be either a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a>, a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_symbol-function.html" target="_top"><code class="function">SYMBOL-FUNCTION</code></a>
 return value, or a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-3.html">lambda expression</a>.  The <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-3.html">lambda expression</a> is thereby
 immediately converted to a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a>.</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="defun"></a>3.1.6. Macros <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defun.html" target="_top"><code class="function">DEFUN</code></a> &amp; <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmacro.html" target="_top"><code class="function">DEFMACRO</code></a></h3></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defun.html" target="_top"><code class="function">DEFUN</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmacro.html" target="_top"><code class="function">DEFMACRO</code></a> are allowed in non-toplevel positions. As
 an example, consider the old (<a class="xref" href="#CLtL1" title="Common Lisp: the Language (1st Edition)">[<abbr class="abbrev">CLtL1</abbr>]</a>) definition of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_gensym.html" target="_top"><code class="function">GENSYM</code></a>:</p><pre class="programlisting">
(let ((gensym-prefix "G")
      (gensym-count 1))
  (defun gensym (&amp;optional (x nil s))
    (when s
      (cond ((stringp x) (setq gensym-prefix x))
            ((integerp x)
             (if (minusp x)
               (error "~S: index ~S is negative" 'gensym x)
               (setq gensym-count x)))
            (t (error "~S: argument ~S of wrong type" 'gensym x))))
    (prog1
      (make-symbol
        (concatenate 'string
          gensym-prefix
          (write-to-string gensym-count :base 10 :radix nil)))
      (incf gensym-count))))
</pre><p>See also <a class="xref" href="#minimal-compilation" title="3.2.2.2. Minimal Compilation sec_3-2-2-2">Section 3.2.2.2, “Minimal Compilation   sec_3-2-2-2”</a>.</p><p><a id="arglist"></a><strong>Function <a class="link" href="#arglist" title="Function EXT:ARGLIST"><code class="function">EXT:ARGLIST</code></a>. </strong>Function <code class="code">(<a class="link" href="#arglist" title="Function EXT:ARGLIST"><code class="function">EXT:ARGLIST</code></a> <em class="replaceable"><code>name</code></em>)</code> returns the <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> of
 the function or macro that <em class="replaceable"><code>name</code></em> names and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> if <em class="replaceable"><code>name</code></em> is
 not <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_fboundp.html" target="_top"><code class="function">FBOUNDP</code></a>.  It also <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> when the macro <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> is not
 available due to the compiler optimization settings
 (see <a class="xref" href="#space-decl" title="3.3.7. Declaration SPACE">Section 3.3.7, “Declaration <code class="literal">SPACE</code>”</a>).</p><p><a id="suppress-check-redef"></a><strong>Variable <a class="link" href="#suppress-check-redef" title="Variable CUSTOM:*SUPPRESS-CHECK-REDEFINITION*"><code class="varname">CUSTOM:*SUPPRESS-CHECK-REDEFINITION*</code></a>. </strong>When <strong class="first"><em class="firstterm"><a class="link" href="#suppress-check-redef" title="Variable CUSTOM:*SUPPRESS-CHECK-REDEFINITION*"><code class="varname">CUSTOM:*SUPPRESS-CHECK-REDEFINITION*</code></a></em></strong> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>,
 <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> issues a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_style-warning.html" target="_top"><code class="classname">STYLE-WARNING</code></a> when a function (macro, variable, class,
 etc) is redefined in a different file than its original definition.
 It is <span class="strong"><strong>not</strong></span> a good idea to set this variable to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.
</p><p><a id="defun-accept-spelalist"></a><strong>Variable <a class="link" href="#defun-accept-spelalist" title="Variable CUSTOM:*DEFUN-ACCEPT-SPECIALIZED-LAMBDA-LIST*"><code class="varname">CUSTOM:*DEFUN-ACCEPT-SPECIALIZED-LAMBDA-LIST*</code></a>. </strong>When <strong class="first"><em class="firstterm"><a class="link" href="#defun-accept-spelalist" title="Variable CUSTOM:*DEFUN-ACCEPT-SPECIALIZED-LAMBDA-LIST*"><code class="varname">CUSTOM:*DEFUN-ACCEPT-SPECIALIZED-LAMBDA-LIST*</code></a></em></strong> is
non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defun.html" target="_top"><code class="function">DEFUN</code></a> accepts <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-3.html">specialized lambda list</a>s, converting type-parameter
associations to type <a class="link" href="#declarations" title="3.3. Declarations sec_3-3">declarations</a>:
</p><pre class="programlisting">(defun f ((x list) (y integer)) ...)</pre><p>
is equivalent to
</p><pre class="programlisting">(defun f (x y) (declare (type list x) (type integer y)) ...)</pre><p>
This extension is disabled by <code class="option"><a href="clisp.html#opt-ansi" class="olink">-ansi</a></code> and by setting <a href="impnotes.html#ansi" class="olink"><code class="varname">CUSTOM:*ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>,
but can be re-enabled by setting <a class="link" href="#defun-accept-spelalist" title="Variable CUSTOM:*DEFUN-ACCEPT-SPECIALIZED-LAMBDA-LIST*"><code class="varname">CUSTOM:*DEFUN-ACCEPT-SPECIALIZED-LAMBDA-LIST*</code></a> explicitly.
</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="compilation"></a>3.2. Compilation
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-2.html">[sec_3-2]</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#compiler-terms">3.2.1. Compiler Terminology   sec_3-2-1</a></span></dt><dd><dl><dt><span class="section"><a href="#compile-jit">3.2.1.1. Just-In-Time Native Compilation</a></span></dt></dl></dd><dt><span class="section"><a href="#compilation-semantics">3.2.2. Compilation Semantics   sec_3-2-2</a></span></dt><dd><dl><dt><span class="section"><a href="#compiler-macros">3.2.2.1. Compiler Macros   sec_3-2-2-1</a></span></dt><dt><span class="section"><a href="#minimal-compilation">3.2.2.2. Minimal Compilation   sec_3-2-2-2</a></span></dt><dt><span class="section"><a href="#semantic-constraints">3.2.2.3. Semantic Constraints   sec_3-2-2-3</a></span></dt></dl></dd><dt><span class="section"><a href="#similarity">3.2.3. Definition of Similarity   sec_3-2-4-2-2</a></span></dt><dt><span class="section"><a href="#compile-errors">3.2.4. Exceptional Situations in the Compiler   sec_3-2-5</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="compiler-terms"></a>3.2.1. Compiler Terminology
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-2-1.html">[sec_3-2-1]</a></h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#compile-jit">3.2.1.1. Just-In-Time Native Compilation</a></span></dt></dl></div><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> compiles to platform-independent <a href="impnotes.html#bytecode" class="olink">bytecode</a>.</p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="compile-jit"></a>3.2.1.1. Just-In-Time Native Compilation</h4></div><div><h5 class="subtitle"><span class="plat-dep">Platform Dependent: <span class="plat-dep">Only in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> built <span class="strong"><strong>with</strong></span>
   <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/lightning/" target="_top">lightning</a></span></span></h5></div></div></div><p>The code compiled to <a href="impnotes.html#bytecode" class="olink">bytecode</a>s with optimization levels
 </p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_or.html" target="_top"><code class="function">OR</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eqcm_sleq__lteqcm_gteq.html" target="_top"><code class="function">&gt;=</code></a> 0 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_optimize.html" target="_top"><code class="literal">SPACE</code></a>) (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eqcm_sleq__lteqcm_gteq.html" target="_top"><code class="function">&lt;=</code></a> 1 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_optimize.html" target="_top"><code class="literal">SPEED</code></a>))</pre><p>
 (by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile.html" target="_top"><code class="function">COMPILE</code></a>, <a href="impnotes.html#compilefile" class="olink"><code class="function">COMPILE-FILE</code></a>, or <a class="link" href="#compile-decl" title="3.3.6. Declaration (COMPILE)"><code class="code">(COMPILE)</code></a>) will be
 <span class="emphasis"><em>just-in-time</em></span> (i.e., on the first execution)
 compiled to native code using <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/lightning/" target="_top">lightning</a>.
</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="compilation-semantics"></a>3.2.2. Compilation Semantics
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-2-2.html">[sec_3-2-2]</a></h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#compiler-macros">3.2.2.1. Compiler Macros   sec_3-2-2-1</a></span></dt><dt><span class="section"><a href="#minimal-compilation">3.2.2.2. Minimal Compilation   sec_3-2-2-2</a></span></dt><dt><span class="section"><a href="#semantic-constraints">3.2.2.3. Semantic Constraints   sec_3-2-2-3</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="compiler-macros"></a>3.2.2.1. Compiler Macros
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-2-2-1.html">[sec_3-2-2-1]</a></h4></div></div></div><p>Compiler macros are expanded in the compiled code only, and
ignored by the interpreter.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="minimal-compilation"></a>3.2.2.2. Minimal Compilation
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-2-2-2.html">[sec_3-2-2-2]</a></h4></div></div></div><p>When a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defun.html" target="_top"><code class="function">DEFUN</code></a> form is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eval.html" target="_top"><code class="function">EVAL</code></a>uated, the macros used there are
 expanded, so they must be already defined, and their (re)definition
 does <span class="strong"><strong>not</strong></span> affect functions which are already defined.</p><p>This means that even the interpreted code is <span class="emphasis"><em>minimally
  compiled</em></span> in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="semantic-constraints"></a>3.2.2.3. Semantic Constraints
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-2-2-3.html">[sec_3-2-2-3]</a></h4></div></div></div><p>Non-conforming code that does not follow the rule
 </p><div class="blockquote"><blockquote class="blockquote"><p><span class="quote">“<span class="quote">Special proclamations for dynamic variables must
    be made in the compilation environment.</span>”</span></p></blockquote></div><p>
 can produce quite unexpected results, e.g., observable differences
 between <span class="emphasis"><em>compiled</em></span> and <span class="emphasis"><em>interpreted</em></span>
 programs:</p><pre class="programlisting">
(defun adder-c (value) (declare <a class="link" href="#compile-decl" title="3.3.6. Declaration (COMPILE)"><code class="code">(COMPILE)</code></a>) (lambda (x) (+ x value)))
⇒ <code class="computeroutput">ADDER-C</code><strong>	; </strong><em class="lineannotation"><span class="lineannotation">compiled function; <em class="replaceable"><code>value</code></em> is lexical</span></em>
(defun adder-i (value) (lambda (x) (+ x value)))
⇒ <code class="computeroutput">ADDER-I</code><strong>	; </strong><em class="lineannotation"><span class="lineannotation">interpreted function; <em class="replaceable"><code>value</code></em> is lexical</span></em>
(defparameter add-c-10 (adder-c 10))
⇒ <code class="computeroutput">ADD-C-10</code><strong>	; </strong><em class="lineannotation"><span class="lineannotation">compiled function</span></em>
(defparameter add-i-10 (adder-i 10))
⇒ <code class="computeroutput">ADD-I-10</code><strong>	; </strong><em class="lineannotation"><span class="lineannotation">interpreted function</span></em>
(funcall add-c-10 32)
⇒ <code class="computeroutput">42</code><strong>	; </strong><em class="lineannotation"><span class="lineannotation">as expected</span></em>
(funcall add-i-10 32)
⇒ <code class="computeroutput">42</code><strong>	; </strong><em class="lineannotation"><span class="lineannotation">as expected</span></em>
(defvar value 12)
⇒ <code class="computeroutput">VALUE</code><strong>	; </strong><em class="lineannotation"><span class="lineannotation">affects <code class="function">ADDER-I</code> and <code class="function">ADD-I-10</code> but <span class="strong"><strong>not</strong></span> <code class="function">ADDER-C</code> and <code class="function">ADD-C-10</code></span></em>
(funcall add-c-10 32)
⇒ <code class="computeroutput">42</code><strong>	; </strong><em class="lineannotation"><span class="lineannotation">as before</span></em>
(funcall add-i-10 32)
⇒ <code class="computeroutput">44</code><strong>	; </strong><em class="lineannotation"><span class="lineannotation"><em class="replaceable"><code>value</code></em> is now dynamic!</span></em>
</pre><p><a id="semantic-constraints-non-conf"></a><strong>Non-conformance. </strong>The code shown above has a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_special.html" target="_top"><code class="literal">SPECIAL</code></a> proclamation (by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defparametercm_defvar.html" target="_top"><code class="function">DEFVAR</code></a>)
 for the variable <em class="replaceable"><code>value</code></em> in the execution environment
 (before the last two <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_funcall.html" target="_top"><code class="function">FUNCALL</code></a>s)
 but not in the compilation environment: at the moment
 the <code class="function">ADDER-I</code> function is defined,
 <em class="replaceable"><code>value</code></em> is not known to be a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_special.html" target="_top"><code class="literal">SPECIAL</code></a> variable.
 Therefore the code is not conforming.</p><div class="simplesect"><div class="titlepage"><div><div><h5 class="title"><a id="semantic-constraints-rationale"></a>Rationale</h5></div></div></div><p>The function <code class="function">ADD-C-10</code> was compiled <span class="strong"><strong>before</strong></span>
 <em class="replaceable"><code>value</code></em> was declared <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_special.html" target="_top"><code class="literal">SPECIAL</code></a>, so the symbol <em class="replaceable"><code>value</code></em> was
 eliminated from its code and the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_special.html" target="_top"><code class="literal">SPECIAL</code></a> declaration did
 not affect the return value (i.e., <code class="code">(funcall
  add-c-10 32)</code> always returned <span class="returnvalue">42</span>).</p><p>On the opposite, function <code class="function">ADDER-I</code> was <span class="strong"><strong>not</strong></span>
 compiled, so <code class="function">ADD-I-10</code>
 was <span class="emphasis"><em>interpreted</em></span>.
 Whenever <code class="function">ADD-I-10</code> is executed, its definition is
 interpreted all over again.  Before <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defparametercm_defvar.html" target="_top"><code class="function">DEFVAR</code></a>, <em class="replaceable"><code>value</code></em> is evaluated as
 a lexical (because it is <span class="strong"><strong>not</strong></span> declared <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_special.html" target="_top"><code class="literal">SPECIAL</code></a> yet), but after
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defparametercm_defvar.html" target="_top"><code class="function">DEFVAR</code></a>, we see a globally <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_special.html" target="_top"><code class="literal">SPECIAL</code></a> symbol <em class="replaceable"><code>value</code></em> which
 can have only a global <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_symbol-value.html" target="_top"><code class="function">SYMBOL-VALUE</code></a> (not a local binding), and thus
 we are compelled to evaluate it to <span class="returnvalue">12</span>.</p><p>This behavior was implemented intentionally to ease interactive
 development, because <span class="emphasis"><em>usually</em></span>
 the <code class="function">ADDER-I</code> above would be followed by a
 (forgotten) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defparametercm_defvar.html" target="_top"><code class="function">DEFVAR</code></a>.</p><p>When a user compiles a program, the compiler is allowed to
 remember the information whether a variable was <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_special.html" target="_top"><code class="literal">SPECIAL</code></a> or not,
 because that allows the compiler to generate more efficient code,
 but in interpreted code, when the user changes the state of a variable,
 he does <span class="strong"><strong>not</strong></span> want to re-evaluate all <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defun.html" target="_top"><code class="function">DEFUN</code></a>s that use the variable.</p><p>[<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] gives the implementation freedom regarding
 interpreted evaluation, how much it wants to remember / cache, and how
 much it wants to re-evaluate according the current <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1.html">environment</a>,
 if it has changed. <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> implements <span class="emphasis"><em>ad-hoc
  look-up</em></span> for variables (but <span class="strong"><strong>not</strong></span> for macros, see
 <a class="xref" href="#minimal-compilation" title="3.2.2.2. Minimal Compilation sec_3-2-2-2">Section 3.2.2.2, “Minimal Compilation   sec_3-2-2-2”</a>).</p></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="similarity"></a>3.2.3. Definition of Similarity
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-2-4-2-2.html">[sec_3-2-4-2-2]</a></h3></div></div></div><p>Hash tables are <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-2-4-1.html">externalizable object</a>s.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="compile-errors"></a>3.2.4. Exceptional Situations in the Compiler
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-2-5.html">[sec_3-2-5]</a></h3></div></div></div><p>Both <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile.html" target="_top"><code class="function">COMPILE</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eval.html" target="_top"><code class="function">EVAL</code></a> may <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a> the <a class="link" href="#compile-errors" title="3.2.4. Exceptional Situations in the Compiler sec_3-2-5"><code class="classname">EXT:SOURCE-PROGRAM-ERROR</code></a>
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_condition.html" target="_top"><code class="classname">CONDITION</code></a> which derives from <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_program-error.html" target="_top"><code class="classname">PROGRAM-ERROR</code></a> and which contains
 additional slots with accessors </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="link" href="#compile-errors" title="3.2.4. Exceptional Situations in the Compiler sec_3-2-5"><code class="function">EXT:SOURCE-PROGRAM-ERROR-FORM</code></a></span></dt><dd>Returns the whole form in which the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> was
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed</dd><dt><span class="term"><a class="link" href="#compile-errors" title="3.2.4. Exceptional Situations in the Compiler sec_3-2-5"><code class="function">EXT:SOURCE-PROGRAM-ERROR-DETAIL</code></a></span></dt><dd>Returns the specific (usually small) part of the
   above which triggered the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a></dd></dl></div><p><a id="key-optional"></a><strong>Mixing <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>. </strong>It is a bad design to have both <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> in the
same <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a>, especially if the number of optional arguments is even:
the users will often forget to supply optional arguments when supplying
keys, e.g., <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-from-string.html" target="_top"><code class="function">READ-FROM-STRING</code></a> <em class="replaceable"><code>string</code></em> <code class="constant">:START</code> 5)</code>
instead of <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-from-string.html" target="_top"><code class="function">READ-FROM-STRING</code></a> <em class="replaceable"><code>string</code></em> t nil <code class="constant">:START</code> 5)</code>.
This is why the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> compiler issues a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_style-warning.html" target="_top"><code class="classname">STYLE-WARNING</code></a> in such cases:
</p><pre class="programlisting">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defun.html" target="_top"><code class="function">DEFUN</code></a> foo (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> b) (cons a b))
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile.html" target="_top"><code class="function">COMPILE</code></a> 'foo)
WARNING: in FOO : Mixing <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> in lambda list (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> A <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> B) is bad design
FOO ;
1 ;
NIL
</pre></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="declarations"></a>3.3. Declarations
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-3.html">[sec_3-3]</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#decl-min">3.3.1. Minimal Declaration Processing Requirements   sec_3-3-1</a></span></dt><dt><span class="section"><a href="#spec-decl">3.3.2. Declaration <code class="literal">SPECIAL</code></a></span></dt><dt><span class="section"><a href="#constant-notinline">3.3.3. Declaration <code class="literal">EXT:CONSTANT-NOTINLINE</code></a></span></dt><dt><span class="section"><a href="#constantp">3.3.4. Function <code class="function">CONSTANTP</code></a></span></dt><dt><span class="section"><a href="#safety-decl">3.3.5. Declaration <code class="literal">SAFETY</code></a></span></dt><dt><span class="section"><a href="#compile-decl">3.3.6. Declaration <code class="code">(COMPILE)</code></a></span></dt><dt><span class="section"><a href="#space-decl">3.3.7. Declaration <code class="literal">SPACE</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="decl-min"></a>3.3.1. Minimal Declaration Processing Requirements
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-3-1.html">[sec_3-3-1]</a></h3></div></div></div><p>The type declarations <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_type.html" target="_top"><code class="literal">TYPE</code></a> <em class="replaceable"><code>type</code></em> <em class="replaceable"><code>variable</code></em> ...)</code>
 and <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_ftype.html" target="_top"><code class="literal">FTYPE</code></a> <em class="replaceable"><code>type</code></em> <em class="replaceable"><code>function</code></em> ...)</code>
 are ignored by both the interpreter and the compiler.
 Use <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_check-type.html" target="_top"><code class="function">CHECK-TYPE</code></a> to force type checks.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="spec-decl"></a>3.3.2. Declaration <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_special.html" target="_top"><code class="literal">SPECIAL</code></a></h3></div></div></div><p><a id="notspec-decl"></a><strong>Declaration <a class="link" href="#notspec-decl" title="Declaration EXT:NOTSPECIAL"><code class="literal">EXT:NOTSPECIAL</code></a>. </strong>Declarations <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_proclaim.html" target="_top"><code class="function">PROCLAIM</code></a> '(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_special.html" target="_top"><code class="literal">SPECIAL</code></a> <em class="replaceable"><code>variable</code></em>))</code>
 and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defconstant.html" target="_top"><code class="function">DEFCONSTANT</code></a> are undone by the <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_proclaim.html" target="_top"><code class="function">PROCLAIM</code></a> '(<a class="link" href="#notspec-decl" title="Declaration EXT:NOTSPECIAL"><code class="literal">EXT:NOTSPECIAL</code></a>
  <em class="replaceable"><code>variable</code></em>))</code> declaration.  This declaration can be used only in
 global <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_proclaim.html" target="_top"><code class="function">PROCLAIM</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_declaim.html" target="_top"><code class="function">DECLAIM</code></a> forms, <span class="strong"><strong>not</strong></span> in local <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sym_declare.html" target="_top"><code class="function">DECLARE</code></a> forms.
</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>You cannot expect miracles: functions compiled <span class="strong"><strong>before</strong></span>
 the <a class="link" href="#notspec-decl" title="Declaration EXT:NOTSPECIAL"><code class="literal">EXT:NOTSPECIAL</code></a> proclamation was issued will still be treating <em class="replaceable"><code>variable</code></em> as
 special even after the <a class="link" href="#notspec-decl" title="Declaration EXT:NOTSPECIAL"><code class="literal">EXT:NOTSPECIAL</code></a> proclamation. See also
 <a class="xref" href="#semantic-constraints" title="3.2.2.3. Semantic Constraints sec_3-2-2-3">Section 3.2.2.3, “Semantic Constraints   sec_3-2-2-3”</a>.</p></div><p><a id="spe-var-p"></a><strong>Function <a class="link" href="#spe-var-p" title="Function EXT:SPECIAL-VARIABLE-P"><code class="function">EXT:SPECIAL-VARIABLE-P</code></a>. </strong>You can use the function <code class="code">(<a class="link" href="#spe-var-p" title="Function EXT:SPECIAL-VARIABLE-P"><code class="function">EXT:SPECIAL-VARIABLE-P</code></a> <em class="replaceable"><code>symbol</code></em>
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-4.html">environment</a></code></em>)</code> to check whether the <em class="replaceable"><code>symbol</code></em> is a
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-1-2.html">dynamic variable</a>.  <em class="replaceable"><code><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-4.html">environment</a></code></em> of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> or omitted means use the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-1.html">global environment</a>.
 You can also obtain the current <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a> using the macro
 <a class="link" href="#the-env" title="Macro EXT:THE-ENVIRONMENT"><code class="function">EXT:THE-ENVIRONMENT</code></a> (interpreted code only).
 This function will always return <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> for global special
 variables and <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-1-3.html">constant variable</a>s.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="constant-notinline"></a>3.3.3. Declaration <a class="link" href="#constant-notinline" title="3.3.3. Declaration EXT:CONSTANT-NOTINLINE"><code class="literal">EXT:CONSTANT-NOTINLINE</code></a></h3></div></div></div><p>Constants defined by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defconstant.html" target="_top"><code class="function">DEFCONSTANT</code></a> but proclaimed <a class="link" href="#constant-notinline" title="3.3.3. Declaration EXT:CONSTANT-NOTINLINE"><code class="literal">EXT:CONSTANT-NOTINLINE</code></a>
  will not be inlined by the compiler. This is useful for variables
  which remain constant within an a single Lisp process but may vary
  between processes and machines (such as endianness or word size) thus
  they should be written to <code class="filename">#P".fas"</code>s as symbols, not values.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="constantp"></a>3.3.4. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_constantp.html" target="_top"><code class="function">CONSTANTP</code></a></h3></div></div></div><p>Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_constantp.html" target="_top"><code class="function">CONSTANTP</code></a> fully complies with [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>].
Additionally, some non-trivial forms are identified as constants, e.g.,
<code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_constantp.html" target="_top"><code class="function">CONSTANTP</code></a> '(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_pl.html" target="_top"><code class="function">+</code></a> 1 2 3))</code> returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>Since <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defconstant.html" target="_top"><code class="function">DEFCONSTANT</code></a> initial value forms are not
evaluated at compile time, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_constantp.html" target="_top"><code class="function">CONSTANTP</code></a> will not report <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> of their
name within the same <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#compilation_unit">compilation unit</a> for the null <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a>.
This is consistent and matches questionable code using the pattern
<code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_if.html" target="_top"><code class="function">IF</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_constantp.html" target="_top"><code class="function">CONSTANTP</code></a> <em class="replaceable"><code>form</code></em>) (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eval.html" target="_top"><code class="function">EVAL</code></a> <em class="replaceable"><code>form</code></em>))</code>.
Use <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_eval-when.html" target="_top"><code class="function">EVAL-WHEN</code></a> if you need recognition and the value during
compile-time. See also <a class="xref" href="#compile-time-value" title="31.11.5. Macro EXT:COMPILE-TIME-VALUE">Section 31.11.5, “Macro <code class="function">EXT:COMPILE-TIME-VALUE</code>”</a>.
</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="safety-decl"></a>3.3.5. Declaration <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_optimize.html" target="_top"><code class="literal">SAFETY</code></a></h3></div></div></div><p>Declaration <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_optimize.html" target="_top"><code class="literal">OPTIMIZE</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_optimize.html" target="_top"><code class="literal">SAFETY</code></a> 3))</code>
 results in <span class="quote">“<span class="quote">safe</span>”</span> compiled code: function calls are never
 eliminated. This guarantees the semantics described in
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-5.html">[sec_3-5]</a>.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="compile-decl"></a>3.3.6. Declaration <a class="link" href="#compile-decl" title="3.3.6. Declaration (COMPILE)"><code class="code">(COMPILE)</code></a></h3></div></div></div><p>The declaration <a class="link" href="#compile-decl" title="3.3.6. Declaration (COMPILE)"><code class="code">(COMPILE)</code></a> has the effect that the current
 form is compiled prior to execution.  Examples:
</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_locally.html" target="_top"><code class="function">LOCALLY</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sym_declare.html" target="_top"><code class="function">DECLARE</code></a> (compile)) <em class="replaceable"><code>form</code></em>)</pre><p>
executes the compiled version of <em class="replaceable"><code>form</code></em>.</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET</code></a> ((x 0))
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_fletcm_scm_macrolet.html" target="_top"><code class="function">FLET</code></a> ((inc () (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sym_declare.html" target="_top"><code class="function">DECLARE</code></a> (compile)) (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_incfcm_decf.html" target="_top"><code class="function">INCF</code></a> x))
         (dec () (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_incfcm_decf.html" target="_top"><code class="function">DECF</code></a> x)))
    (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_values.html" target="_top"><code class="function">VALUES</code></a> #'inc #'dec)))</pre><p>
 returns two functions.  The first is compiled and increments <em class="replaceable"><code>x</code></em>, the
 second is interpreted (slower) and decrements the same <em class="replaceable"><code>x</code></em>.</p><p>This declaration can also be used to name the resulting compiled closure:
</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_lambda.html" target="_top"><code class="function">LAMBDA</code></a> (x) (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sym_declare.html" target="_top"><code class="function">DECLARE</code></a> (compile ident)) x)
⇒ <code class="computeroutput"><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html"><span class="data"><code class="literal">#&lt;</code></span></a><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_compiled-function.html" target="_top"><code class="classname">COMPILED-FUNCTION</code></a> IDENT&gt;</code>
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_function-_a-expression.html" target="_top"><code class="function">FUNCTION-LAMBDA-EXPRESSION</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stcm_ststcm_ststst.html" target="_top"><code class="varname">*</code></a>)
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></code><strong>	; </strong><em class="lineannotation"><span class="lineannotation">source is not preserved</span></em>
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a></code>
⇒ <code class="computeroutput">IDENT</code>
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_fboundp.html" target="_top"><code class="function">FBOUNDP</code></a> 'ident)
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></code><strong>	; </strong><em class="lineannotation"><span class="lineannotation">sic!</span></em>
</pre><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>The declaration <a class="link" href="#compile-decl" title="3.3.6. Declaration (COMPILE)"><code class="code">(COMPILE)</code></a> is ignored by the following
  <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_s.html#special_operator">special operator</a>s:
  </p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_fletcm_scm_macrolet.html" target="_top"><code class="function">LABELS</code></a></td></tr><tr><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_fletcm_scm_macrolet.html" target="_top"><code class="function">FLET</code></a></td></tr><tr><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_fletcm_scm_macrolet.html" target="_top"><code class="function">MACROLET</code></a></td></tr></table></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="space-decl"></a>3.3.7. Declaration <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_optimize.html" target="_top"><code class="literal">SPACE</code></a></h3></div></div></div><p>The declaration determines what metadata is recorded in the
 function object:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_optimize.html" target="_top"><code class="literal">SPACE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eqcm_sleq__lteqcm_gteq.html" target="_top"><code class="function">&gt;=</code></a> 2</span></dt><dd>documentation string is discarded
  </dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_optimize.html" target="_top"><code class="literal">SPACE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eqcm_sleq__lteqcm_gteq.html" target="_top"><code class="function">&gt;=</code></a> 3</span></dt><dd>the original <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> is also discarded (most
     information is still available, see <a href="impnotes.html#describe" class="olink"><code class="function">DESCRIBE</code></a>, but the names of
     the positional arguments are not).</dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="lalist"></a>3.4. Lambda Lists
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4.html">[sec_3-4]</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#boa-lalist">3.4.1. Boa Lambda Lists   sec_3-4-6</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="boa-lalist"></a>3.4.1. Boa Lambda Lists
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-6.html">[sec_3-4-6]</a></h3></div></div></div><p>The initial value of an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;AUX</code></a> variable in a boa <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> is
 the value of the corresponding slot's initial form.</p></div></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="types-classes"></a>Chapter 4. Types and Classes
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-4.html">[chap-4]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#types">4.1. Types sec_4-2</a></span></dt><dd><dl><dt><span class="section"><a href="#type-spec">4.1.1. Type Specifiers   sec_4-2-3</a></span></dt></dl></dd><dt><span class="section"><a href="#classes">4.2. Classes   sec_4-3</a></span></dt><dt><span class="section"><a href="#clos-diff">4.3. Deviations from ANSI CL standard</a></span></dt><dt><span class="section"><a href="#metaclasses">4.4. Standard Metaclasses   sec_4-3-1-1</a></span></dt><dt><span class="section"><a href="#def-class">4.5. Defining Classes   sec_4-3-2</a></span></dt><dt><span class="section"><a href="#redef-class">4.6. Redefining Classes   sec_4-3-6</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="types"></a>4.1. Types <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_4-2.html">[sec_4-2]</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#type-spec">4.1.1. Type Specifiers   sec_4-2-3</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="type-spec"></a>4.1.1. Type Specifiers
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_4-2-3.html">[sec_4-2-3]</a></h3></div></div></div><p>The general form of the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_complex.html" target="_top"><code class="classname">COMPLEX</code></a> <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_t.html#type_specifier">type specifier</a> is <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_complex.html" target="_top"><code class="classname">COMPLEX</code></a> <em class="replaceable"><code>type-of-real-part</code></em>
 <em class="replaceable"><code>type-of-imaginary-part</code></em>)</code></span>.
 The <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_t.html#type_specifier">type specifier</a> <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_complex.html" target="_top"><code class="classname">COMPLEX</code></a> <em class="replaceable"><code>type</code></em>)</code></span>
 is equivalent to <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_complex.html" target="_top"><code class="classname">COMPLEX</code></a> <em class="replaceable"><code>type</code></em>
 <em class="replaceable"><code>type</code></em>)</code></span>.</p><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_deftype.html" target="_top"><code class="function">DEFTYPE</code></a> <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a>s are subject to destructuring (nested <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a>s
 are allowed, as in <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmacro.html" target="_top"><code class="function">DEFMACRO</code></a>) and may contain a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;WHOLE</code></a> marker,
 but not an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;ENVIRONMENT</code></a> marker.</p><p><strong>Function <code class="code">(<code class="function">EXT:TYPE-EXPAND</code>
   <em class="replaceable"><code>type</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>once-p</code></em>)</code>. </strong>If <em class="replaceable"><code>type</code></em> is a user-defined <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_t.html#type_specifier">type specifier</a> this will expand it
 recursively until it is no longer a user-defined type
 (unless <em class="replaceable"><code>once-p</code></em> is supplied and non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>).
 Two values are returned - the expansion and an indicator (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>)
 of whether the original <em class="replaceable"><code>type</code></em> was a user-defined <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_t.html#type_specifier">type specifier</a>.
</p><div class="itemizedlist"><p class="title"><strong>The possible results of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_type-of.html" target="_top"><code class="function">TYPE-OF</code></a></strong></p><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_cons.html" target="_top"><code class="classname">CONS</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_null.html" target="_top"><code class="classname">NULL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_boolean.html" target="_top"><code class="classname">BOOLEAN</code></a>,
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_keyword.html" target="_top"><code class="classname">KEYWORD</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_bit.html" target="_top"><code class="classname">BIT</code></a>, <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> 0
    <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-6.html"><span class="data"><code class="literal">#.</code></span></a><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_ative-fixnum.html" target="_top"><code class="constant">MOST-POSITIVE-FIXNUM</code></a>)</code></span>,
   <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>
    <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-6.html"><span class="data"><code class="literal">#.</code></span></a><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_ative-fixnum.html" target="_top"><code class="constant">MOST-NEGATIVE-FIXNUM</code></a> (0))</code></span>,
   <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>
    (<a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-6.html"><span class="data"><code class="literal">#.</code></span></a><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_ative-fixnum.html" target="_top"><code class="constant">MOST-POSITIVE-FIXNUM</code></a>))</code></span>,
   <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> *
    (<a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-6.html"><span class="data"><code class="literal">#.</code></span></a><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_ative-fixnum.html" target="_top"><code class="constant">MOST-NEGATIVE-FIXNUM</code></a>))</code></span></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_rational.html" target="_top"><code class="classname">RATIONAL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SHORT-FLOAT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SINGLE-FLOAT</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">DOUBLE-FLOAT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">LONG-FLOAT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_complex.html" target="_top"><code class="classname">COMPLEX</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_base-char.html" target="_top"><code class="classname">BASE-CHAR</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_standard-char.html" target="_top"><code class="classname">STANDARD-CHAR</code></a></li><li class="listitem"><span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_array.html" target="_top"><code class="classname">ARRAY</code></a> <em class="replaceable"><code>element-type</code></em>
    <em class="replaceable"><code>dimensions</code></em>)</code></span>, <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-array.html" target="_top"><code class="classname">SIMPLE-ARRAY</code></a>
    <em class="replaceable"><code>element-type</code></em> <em class="replaceable"><code>dimensions</code></em>)</code></span></li><li class="listitem"><span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>
    <em class="replaceable"><code>size</code></em>)</code></span>, <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-vector.html" target="_top"><code class="classname">SIMPLE-VECTOR</code></a>
    <em class="replaceable"><code>size</code></em>)</code></span></li><li class="listitem"><span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>
    <em class="replaceable"><code>size</code></em>)</code></span>, <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-string.html" target="_top"><code class="classname">SIMPLE-STRING</code></a>
    <em class="replaceable"><code>size</code></em>)</code></span></li><li class="listitem"><span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_base-string.html" target="_top"><code class="classname">BASE-STRING</code></a>
    <em class="replaceable"><code>size</code></em>)</code></span>, <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-base-string.html" target="_top"><code class="classname">SIMPLE-BASE-STRING</code></a>
    <em class="replaceable"><code>size</code></em>)</code></span></li><li class="listitem"><span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_bit-vector.html" target="_top"><code class="classname">BIT-VECTOR</code></a>
    <em class="replaceable"><code>size</code></em>)</code></span>, <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-bit-vector.html" target="_top"><code class="classname">SIMPLE-BIT-VECTOR</code></a>
    <em class="replaceable"><code>size</code></em>)</code></span></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_compiled-function.html" target="_top"><code class="classname">COMPILED-FUNCTION</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_file-stream.html" target="_top"><code class="classname">FILE-STREAM</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_synonym-stream.html" target="_top"><code class="classname">SYNONYM-STREAM</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_broadcast-stream.html" target="_top"><code class="classname">BROADCAST-STREAM</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_concatenated-stream.html" target="_top"><code class="classname">CONCATENATED-STREAM</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_two-way-stream.html" target="_top"><code class="classname">TWO-WAY-STREAM</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_echo-stream.html" target="_top"><code class="classname">ECHO-STREAM</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string-stream.html" target="_top"><code class="classname">STRING-STREAM</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_package.html" target="_top"><code class="classname">PACKAGE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_readtable.html" target="_top"><code class="classname">READTABLE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_pathname.html" target="_top"><code class="classname">PATHNAME</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_logical-pathname.html" target="_top"><code class="classname">LOGICAL-PATHNAME</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_random-state.html" target="_top"><code class="classname">RANDOM-STATE</code></a>, <a class="link" href="#byte-type" title="12.2.1.4. Byte Operations on Integers sec_12-1-1-3-2"><span class="type">BYTE</span></a></li><li class="listitem"><code class="classname">SPECIAL-OPERATOR</code>,
   <code class="classname">LOAD-TIME-EVAL</code>, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-symbol-macro.html"><code class="classname">SYMBOL-MACRO</code></a>,
   <code class="classname">GLOBAL-SYMBOL-MACRO</code>, <a class="link" href="#encoding" title="31.5. Encodings"><code class="classname">EXT:ENCODING</code></a>,
   <a class="link" href="#fptr"><code class="classname">FFI:FOREIGN-POINTER</code></a>, <a class="link" href="#faddr"><code class="classname">FFI:FOREIGN-ADDRESS</code></a>, <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a>,
   <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a></li><li class="listitem"><a class="link" href="#weak-pointer" title="31.7.1. Weak Pointers"><code class="classname">EXT:WEAK-POINTER</code></a>, <a class="link" href="#weak-list" title="31.7.2. Weak Lists"><code class="classname">EXT:WEAK-LIST</code></a>, <a class="link" href="#weak-and-relation" title="31.7.3. Weak “And” Relations"><code class="classname">EXT:WEAK-AND-RELATION</code></a>,
   <a class="link" href="#weak-or-relation" title="31.7.4. Weak “Or” Relations"><code class="classname">EXT:WEAK-OR-RELATION</code></a>, <a class="link" href="#weak-mapping" title="31.7.5. Weak Associations"><code class="classname">EXT:WEAK-MAPPING</code></a>, <a class="link" href="#weak-and-mapping" title="31.7.6. Weak “And” Mappings"><code class="classname">EXT:WEAK-AND-MAPPING</code></a>,
   <a class="link" href="#weak-or-mapping" title="31.7.7. Weak “Or” Mappings"><code class="classname">EXT:WEAK-OR-MAPPING</code></a>, <a class="link" href="#weak-alist" title="31.7.8. Weak Association Lists"><code class="classname">EXT:WEAK-ALIST</code></a>,
   <a class="link" href="#reader" title="Chapter 23. Reader chap-23"><code class="classname">READ-LABEL</code></a>,
   <a class="link" href="#reader" title="Chapter 23. Reader chap-23"><code class="classname">FRAME-POINTER</code></a>,
   <code class="classname">SYSTEM-INTERNAL</code></li><li class="listitem"><code class="classname">ADDRESS</code> (should not
  occur)</li><li class="listitem">any other <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a> (structure types or <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a>
  classes)</li><li class="listitem">a class object (<a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> classes without a
   <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#proper_name">proper name</a>)</li></ul></div><p><a id="fixnum-char-ansi"></a><strong>Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_coerce.html" target="_top"><code class="function">COERCE</code></a>. </strong><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_fixnum.html" target="_top"><code class="classname">FIXNUM</code></a> is not a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#character_designator">character
  designator</a> in [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>], although <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> provides an
  obvious venue to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_coerce.html" target="_top"><code class="function">COERCE</code></a> a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_fixnum.html" target="_top"><code class="classname">FIXNUM</code></a> to a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>.
  When <a class="link" href="#fixnum-char-ansi" title="Function COERCE"><code class="varname">CUSTOM:*COERCE-FIXNUM-CHAR-ANSI*</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_coerce.html" target="_top"><code class="function">COERCE</code></a>s <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_fixnum.html" target="_top"><code class="classname">FIXNUM</code></a>s to
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>s via <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a>.
  When <a class="link" href="#fixnum-char-ansi" title="Function COERCE"><code class="varname">CUSTOM:*COERCE-FIXNUM-CHAR-ANSI*</code></a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_fixnum.html" target="_top"><code class="classname">FIXNUM</code></a>s cannot be
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_coerce.html" target="_top"><code class="function">COERCE</code></a>d to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>s.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="classes"></a>4.2. Classes
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_4-3.html">[sec_4-3]</a></h2></div></div></div><p>The <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> symbols are <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_export.html" target="_top"><code class="function">EXPORT</code></a>ed from the package <a class="link" href="#classes" title="4.2. Classes sec_4-3"><strong class="package"><span class="quote">“<span class="quote">CLOS</span>”</span></strong></a>.
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong></a> uses (as in <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_use-package.html" target="_top"><code class="function">USE-PACKAGE</code></a>) <a class="link" href="#classes" title="4.2. Classes sec_4-3"><strong class="package"><span class="quote">“<span class="quote">CLOS</span>”</span></strong></a> and <a class="link" href="#re-export" title="11.1.3. Function EXT:RE-EXPORT"><code class="function">EXT:RE-EXPORT</code></a>s the
 [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] standard exported symbols (the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> extensions, e.g.,
 those described in <a class="xref" href="#mop-chap" title="Chapter 29. Meta-Object Protocol">Chapter 29, <em>Meta-Object Protocol</em></a>, are <span class="strong"><strong>not</strong></span> <a class="link" href="#re-export" title="11.1.3. Function EXT:RE-EXPORT"><code class="function">EXT:RE-EXPORT</code></a>ed).
 Since <a class="link" href="#make-pack" title="11.1.1. Function MAKE-PACKAGE">the default <code class="constant">:USE</code> argument</a>
 to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-package.html" target="_top"><code class="function">MAKE-PACKAGE</code></a> is <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong></a>, the standard <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> symbols are normally
 visible in all user-defined packages.
 If you do not want them (for example, if you want to use the
 <a class="ulink" href="https://ftp.gnu.org/pub/gnu/clisp/packages/pcl.sept92f.clisp.tar.gz" target="_top">PCL</a>
 implementation of <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> instead of the native one), do the following:
</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defpackage.html" target="_top"><code class="function">DEFPACKAGE</code></a> "CL-NO-CLOS" (:use "CL"))
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_do-symbol_-all-symbols.html" target="_top"><code class="function">DO-EXTERNAL-SYMBOLS</code></a> (<em class="replaceable"><code>symbol</code></em> <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong></a>)
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_shadow.html" target="_top"><code class="function">SHADOW</code></a> <em class="replaceable"><code>symbol</code></em> "CL-NO-CLOS"))
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_do-symbol_-all-symbols.html" target="_top"><code class="function">DO-SYMBOLS</code></a> (<em class="replaceable"><code>symbol</code></em> "CL-NO-CLOS")
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_export.html" target="_top"><code class="function">EXPORT</code></a> <em class="replaceable"><code>symbol</code></em> "CL-NO-CLOS"))
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_in-package.html" target="_top"><code class="function">IN-PACKAGE</code></a> "CL-NO-CLOS")
(<a href="impnotes.html#loadfile" class="olink"><code class="function">LOAD</code></a> "pcl")<strong>	; </strong><em class="lineannotation"><span class="lineannotation">or whatever</span></em>
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defpackage.html" target="_top"><code class="function">DEFPACKAGE</code></a> "MY-USER" (:use "CL-NO-CLOS"))
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_in-package.html" target="_top"><code class="function">IN-PACKAGE</code></a> "MY-USER")
;; your code which uses PCL goes here
</pre></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="clos-diff"></a>4.3. Deviations from [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>]</h2></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> supports the option <code class="constant">:METACLASS</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_structure-class.html" target="_top"><code class="classname">STRUCTURE-CLASS</code></a>.
 This option is necessary in order to define a subclass of a
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defstruct.html" target="_top"><code class="function">DEFSTRUCT</code></a>-defined structure type using <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> instead of
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defstruct.html" target="_top"><code class="function">DEFSTRUCT</code></a>.</p><p>When <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locfun_call-next-method.html" target="_top"><code class="function">CALL-NEXT-METHOD</code></a> is called with arguments, the rule that
 the ordered set of applicable methods must be the same as for the
 original arguments is enforced by the implementation only in
 interpreted code.</p><p><strong class="first"><em class="firstterm"><a class="link" href="#gen-flet"><code class="function">CLOS:GENERIC-FLET</code></a><a id="gen-flet" class="indexterm"></a></em></strong> and
 <strong class="first"><em class="firstterm"><a class="link" href="#gen-labels"><code class="function">CLOS:GENERIC-LABELS</code></a><a id="gen-labels" class="indexterm"></a></em></strong>
 are implemented as macros, not as special operators (as permitted by
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-2-2.html">[sec_3-1-2-1-2-2]</a>).
 They are not imported into the packages <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-2.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP-USER</span>”</span></strong></a> and <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong></a> because
 of the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] issue <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss181.html" target="_top">GENERIC-FLET-POORLY-DESIGNED:DELETE</a>.</p><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_print-object.html" target="_top"><code class="function">PRINT-OBJECT</code></a> is only called on objects of type
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_standard-object.html" target="_top"><code class="classname">STANDARD-OBJECT</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_structure-object.html" target="_top"><code class="classname">STRUCTURE-OBJECT</code></a>.
 It is not called on other objects, like <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_cons.html" target="_top"><code class="classname">CONS</code></a>es
 and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_number.html" target="_top"><code class="classname">NUMBER</code></a>s, due to the performance concerns.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="metaclasses"></a>4.4. Standard Metaclasses
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_4-3-1-1.html">[sec_4-3-1-1]</a></h2></div></div></div><p>Among those classes listed in <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_4-3-7.html#classtypecorrespondence" target="_top">Figure
 4-8</a>, only the following are instances of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_built-in-class.html" target="_top"><code class="classname">BUILT-IN-CLASS</code></a>:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_number.html" target="_top"><code class="classname">NUMBER</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_complex.html" target="_top"><code class="classname">COMPLEX</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_real.html" target="_top"><code class="classname">REAL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_float.html" target="_top"><code class="classname">FLOAT</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_rational.html" target="_top"><code class="classname">RATIONAL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_ratio.html" target="_top"><code class="classname">RATIO</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_sequence.html" target="_top"><code class="classname">SEQUENCE</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_array.html" target="_top"><code class="classname">ARRAY</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_bit-vector.html" target="_top"><code class="classname">BIT-VECTOR</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_cons.html" target="_top"><code class="classname">CONS</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_null.html" target="_top"><code class="classname">NULL</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_package.html" target="_top"><code class="classname">PACKAGE</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_pathname.html" target="_top"><code class="classname">PATHNAME</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_logical-pathname.html" target="_top"><code class="classname">LOGICAL-PATHNAME</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_random-state.html" target="_top"><code class="classname">RANDOM-STATE</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_readtable.html" target="_top"><code class="classname">READTABLE</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_broadcast-stream.html" target="_top"><code class="classname">BROADCAST-STREAM</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_concatenated-stream.html" target="_top"><code class="classname">CONCATENATED-STREAM</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_echo-stream.html" target="_top"><code class="classname">ECHO-STREAM</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string-stream.html" target="_top"><code class="classname">STRING-STREAM</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_file-stream.html" target="_top"><code class="classname">FILE-STREAM</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_synonym-stream.html" target="_top"><code class="classname">SYNONYM-STREAM</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_two-way-stream.html" target="_top"><code class="classname">TWO-WAY-STREAM</code></a>
 </li></ul></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="def-class"></a>4.5. Defining Classes
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_4-3-2.html">[sec_4-3-2]</a></h2></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> supports the <code class="constant">:METACLASS</code> option.  Possible values are
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a> (the default), <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_structure-class.html" target="_top"><code class="classname">STRUCTURE-CLASS</code></a> (which creates
 structure classes, like <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defstruct.html" target="_top"><code class="function">DEFSTRUCT</code></a> does), and user-defined
 meta-classes (see <a class="xref" href="#validate-superclass" title="29.3.6.7. Generic Function CLOS:VALIDATE-SUPERCLASS">Section 29.3.6.7, “Generic Function <code class="function">CLOS:VALIDATE-SUPERCLASS</code>”</a>).</p><p>It is <span class="strong"><strong>not</strong></span> required that the superclasses of a class are
 defined before the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form for the class is evaluated.
 Use <a class="link" href="#mop-chap" title="Chapter 29. Meta-Object Protocol">Meta-Object Protocol</a> generic functions <a class="link" href="#class-finalized-p" title="29.3.3.9. Generic Function CLOS:CLASS-FINALIZED-P"><code class="function">CLOS:CLASS-FINALIZED-P</code></a> to check whether the
 class has been finalized and thus its instances can be created,
 and <a class="link" href="#finalize-inheritance" title="29.3.6.4. Generic Function CLOS:FINALIZE-INHERITANCE"><code class="function">CLOS:FINALIZE-INHERITANCE</code></a> to force class finalization.</p><p>See also <a class="xref" href="#mop-cl-defclass" title="29.3.1. Macro DEFCLASS">Section 29.3.1, “Macro <code class="function">DEFCLASS</code>”</a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="redef-class"></a>4.6. Redefining Classes
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_4-3-6.html">[sec_4-3-6]</a></h2></div></div></div><p>Trivial changes, e.g., those that can occur when doubly loading
 the same code, do not require updating the instances.
 These are the changes that do not modify the set of local slots
 accessible in instances, e.g., changes to slot options <code class="constant">:INITFORM</code>,
 <code class="constant">:DOCUMENTATION</code>, and changes to class options
 <code class="constant">:DEFAULT-INITARGS</code>, <code class="constant">:DOCUMENTATION</code>.</p><p>The instances are updated when they are first accessed, <span class="strong"><strong>not</strong></span> at
 the time when the class is redefined or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_mak_ces-obsolete.html" target="_top"><code class="function">MAKE-INSTANCES-OBSOLETE</code></a> is
 called.  When the class has been redefined several times since the
 instance was last accessed, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_upd_efined-class.html" target="_top"><code class="function">UPDATE-INSTANCE-FOR-REDEFINED-CLASS</code></a> is
 still called just once.</p></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="data"></a>Chapter 5. Data and Control Flow
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-5.html">[chap-5]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#gen-ref">5.1. Generalized Reference   sec_5-1</a></span></dt><dt><span class="section"><a href="#setf-expansion">5.2. Setf Expansions   sec_5-1-1-2</a></span></dt><dt><span class="section"><a href="#extra-places">5.3. Kinds of Places   sec_5-1-2</a></span></dt><dt><span class="section"><a href="#misc-data">5.4. Miscellaneous</a></span></dt><dt><span class="section"><a href="#defconstant">5.5. Macro <code class="function">DEFCONSTANT</code></a></span></dt><dd><dl><dt><span class="section"><a href="#defconstant-similar">5.5.1. Variable <code class="varname">CUSTOM:*SUPPRESS-SIMILAR-CONSTANT-REDEFINITION-WARNING*</code></a></span></dt></dl></dd><dt><span class="section"><a href="#fcase">5.6. Macro <code class="function">EXT:FCASE</code></a></span></dt><dt><span class="section"><a href="#xor">5.7. Function <code class="function">EXT:XOR</code></a></span></dt><dt><span class="section"><a href="#eq">5.8. Function <code class="function">EQ</code></a></span></dt><dt><span class="section"><a href="#func">5.9. Special Operator <code class="function">FUNCTION</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="gen-ref"></a>5.1. Generalized Reference
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_5-1.html">[sec_5-1]</a></h2></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> markers in <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defsetf.html" target="_top"><code class="function">DEFSETF</code></a> <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a>s are supported, but the
 corresponding keywords must appear literally in the program text.</p><p>An attempt to modify read-only data <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>.
 Program text and quoted constants loaded from files are considered
 read-only data.  This check is only performed for strings, not for
 conses, other kinds of arrays, and user-defined data types.</p><p>See also <a class="xref" href="#letf" title="31.11.2. Macros EXT:LETF &amp; EXT:LETF*">Section 31.11.2, “Macros <code class="function">EXT:LETF</code> &amp; <code class="function">EXT:LETF*</code>”</a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="setf-expansion"></a>5.2. Setf Expansions
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_5-1-1-2.html">[sec_5-1-1-2]</a></h2></div></div></div><p><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_get-setf-expansion.html" target="_top"><code class="function">GET-SETF-EXPANSION</code></a> <em class="replaceable"><code>form</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-4.html">environment</a></code></em>)</code>,
 <code class="code">(EXT:GET-SETF-METHOD <em class="replaceable"><code>form</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-4.html">environment</a></code></em>)</code>, and
 <code class="code">(EXT:GET-SETF-METHOD-MULTIPLE-VALUE <em class="replaceable"><code>form</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
  <em class="replaceable"><code><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-4.html">environment</a></code></em>)</code> receive as optional argument <em class="replaceable"><code><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-4.html">environment</a></code></em> the environment
  necessary for macro expansions. In <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-setf-expander.html" target="_top"><code class="function">DEFINE-SETF-EXPANDER</code></a>
  and <code class="function">EXT:DEFINE-SETF-METHOD</code> <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a>s, one can
  specify <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;ENVIRONMENT</code></a> and a variable, which will be bound to the
  environment.  This environment should be passed to all calls of
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_get-setf-expansion.html" target="_top"><code class="function">GET-SETF-EXPANSION</code></a>, <code class="function">EXT:GET-SETF-METHOD</code> and
 <code class="function">EXT:GET-SETF-METHOD-MULTIPLE-VALUE</code>.  If this is
 done, even local macros will be interpreted as places correctly.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="extra-places"></a>5.3. Kinds of Places
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_5-1-2.html">[sec_5-1-2]</a></h2></div></div></div><p>Additional <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a>s:
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_funcall.html" target="_top"><code class="function">FUNCALL</code></a></span></dt><dd><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_funcall.html" target="_top"><code class="function">FUNCALL</code></a> #'<em class="replaceable"><code>symbol</code></em> ...)
     <em class="replaceable"><code>object</code></em>)</code> and
    <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_funcall.html" target="_top"><code class="function">FUNCALL</code></a> '<em class="replaceable"><code>symbol</code></em> ...) <em class="replaceable"><code>object</code></em>)</code>
    are equivalent to <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<em class="replaceable"><code>symbol</code></em> ...) <em class="replaceable"><code>object</code></em>)</code>.
 </dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_progn.html" target="_top"><code class="function">PROGN</code></a></span></dt><dd><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_progn.html" target="_top"><code class="function">PROGN</code></a> <em class="replaceable"><code>form</code></em> ... <em class="replaceable"><code>place</code></em>)
     <em class="replaceable"><code>object</code></em>)</code></dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_locally.html" target="_top"><code class="function">LOCALLY</code></a></span></dt><dd><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_locally.html" target="_top"><code class="function">LOCALLY</code></a> <em class="replaceable"><code>declaration</code></em> ...
     <em class="replaceable"><code>form</code></em> ... <em class="replaceable"><code>place</code></em>) <em class="replaceable"><code>object</code></em>)</code>
  </dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_if.html" target="_top"><code class="function">IF</code></a></span></dt><dd><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_if.html" target="_top"><code class="function">IF</code></a> <em class="replaceable"><code>condition</code></em>
     <em class="replaceable"><code>place<sub>1</sub></code></em>
     <em class="replaceable"><code>place<sub>2</sub></code></em>)
     <em class="replaceable"><code>object</code></em>)</code></dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_set-dispa_ro-character.html" target="_top"><code class="function">GET-DISPATCH-MACRO-CHARACTER</code></a></span></dt><dd><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_set-dispa_ro-character.html" target="_top"><code class="function">GET-DISPATCH-MACRO-CHARACTER</code></a> ...)
     ...)</code> calls <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_set-dispa_ro-character.html" target="_top"><code class="function">SET-DISPATCH-MACRO-CHARACTER</code></a>.
 </dd><dt><span class="term"><a class="link" href="#lfd" title="Arbitrary Precision Floats"><code class="function">EXT:LONG-FLOAT-DIGITS</code></a>:</span></dt><dd><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="link" href="#lfd" title="Arbitrary Precision Floats"><code class="function">EXT:LONG-FLOAT-DIGITS</code></a>) <em class="replaceable"><code>digits</code></em>)</code> sets the
    default mantissa length of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">LONG-FLOAT</code></a>s to <em class="replaceable"><code>digits</code></em> bits.
 </dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_values-list.html" target="_top"><code class="function">VALUES-LIST</code></a></span></dt><dd><p class="simpara"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_values-list.html" target="_top"><code class="function">VALUES-LIST</code></a> <em class="replaceable"><code>list</code></em>) <em class="replaceable"><code>form</code></em>)</code>
    is equivalent to <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_values-list.html" target="_top"><code class="function">VALUES-LIST</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <em class="replaceable"><code>list</code></em>
     (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_multiple-value-list.html" target="_top"><code class="function">MULTIPLE-VALUE-LIST</code></a> <em class="replaceable"><code>form</code></em>)))</code>.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>Note that this <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a> is restricted: it can only be
     used in <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>, <a class="link" href="#letf" title="31.11.2. Macros EXT:LETF &amp; EXT:LETF*"><code class="function">EXT:LETF</code></a>, <a class="link" href="#letf" title="31.11.2. Macros EXT:LETF &amp; EXT:LETF*"><code class="function">EXT:LETF*</code></a>, not in other positions.
 </p></div></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="misc-data"></a>5.4. Miscellaneous</h2></div></div></div><div class="simplesect"><div class="titlepage"><div><div><h3 class="title"><a id="fle"></a>Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_function-_a-expression.html" target="_top"><code class="function">FUNCTION-LAMBDA-EXPRESSION</code></a></h3></div></div></div><p>The <em class="replaceable"><code>name</code></em> of a <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a> is a <span class="emphasis"><em>string</em></span>
(the name of the underlying <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> function), not a lisp <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_f.html#function_name">function name</a>.
</p></div><div class="simplesect"><div class="titlepage"><div><div><h3 class="title"><a id="des-bind"></a>Macro <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_destructuring-bind.html" target="_top"><code class="function">DESTRUCTURING-BIND</code></a></h3></div></div></div><p>This macro does not perform full error checking.</p></div><div class="simplesect"><div class="titlepage"><div><div><h3 class="title"><a id="macro-special"></a>Macros <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_prog1cm_prog2.html" target="_top"><code class="function">PROG1</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_prog1cm_prog2.html" target="_top"><code class="function">PROG2</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_and.html" target="_top"><code class="function">AND</code></a>,
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_or.html" target="_top"><code class="function">OR</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_psetq.html" target="_top"><code class="function">PSETQ</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_whencm_unless.html" target="_top"><code class="function">WHEN</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_whencm_unless.html" target="_top"><code class="function">UNLESS</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_cond.html" target="_top"><code class="function">COND</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_casecm_ccasecm_ecase.html" target="_top"><code class="function">CASE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_multiple-value-list.html" target="_top"><code class="function">MULTIPLE-VALUE-LIST</code></a>,
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_multiple-value-bind.html" target="_top"><code class="function">MULTIPLE-VALUE-BIND</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_multiple-value-setq.html" target="_top"><code class="function">MULTIPLE-VALUE-SETQ</code></a></h3></div></div></div><p>These macros are implemented as special operators
 (as permitted by <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-2-2.html">[sec_3-1-2-1-2-2]</a>)
 and, as such, are rather efficient.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="defconstant"></a>5.5. Macro <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defconstant.html" target="_top"><code class="function">DEFCONSTANT</code></a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#defconstant-similar">5.5.1. Variable <code class="varname">CUSTOM:*SUPPRESS-SIMILAR-CONSTANT-REDEFINITION-WARNING*</code></a></span></dt></dl></div><p>The initial value is <span class="strong"><strong>not</strong></span> evaluated at compile time,
 just like with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defparametercm_defvar.html" target="_top"><code class="function">DEFVAR</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defparametercm_defvar.html" target="_top"><code class="function">DEFPARAMETER</code></a>.
 Use <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_eval-when.html" target="_top"><code class="function">EVAL-WHEN</code></a> if you need the value at compile time.</p><p><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-1-3.html">constant variable</a>s may not be bound dynamically or lexically.</p><p>See also <a class="xref" href="#constant-notinline" title="3.3.3. Declaration EXT:CONSTANT-NOTINLINE">Section 3.3.3, “Declaration <code class="literal">EXT:CONSTANT-NOTINLINE</code>”</a>.</p><p>If you need to undo the effects of a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defconstant.html" target="_top"><code class="function">DEFCONSTANT</code></a> form,
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_proclaim.html" target="_top"><code class="function">PROCLAIM</code></a> the symbol <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_special.html" target="_top"><code class="literal">SPECIAL</code></a> (to turn the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-1-3.html">constant variable</a> into a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-1-2.html">dynamic variable</a>),
 and then <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_proclaim.html" target="_top"><code class="function">PROCLAIM</code></a> it <a class="link" href="#notspec-decl" title="Declaration EXT:NOTSPECIAL"><code class="literal">EXT:NOTSPECIAL</code></a> (to turn the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-1-2.html">dynamic variable</a> into a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-1-1.html">lexical variable</a>).
</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>If you follow the usual variable naming convention
 (<code class="varname">*FOO*</code> for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defparametercm_defvar.html" target="_top"><code class="function">DEFVAR</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defparametercm_defvar.html" target="_top"><code class="function">DEFPARAMETER</code></a>,
 <code class="constant">+BAR+</code> for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defconstant.html" target="_top"><code class="function">DEFCONSTANT</code></a>, <code class="varname">ZOT</code>
 for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET</code></a>/<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET*</code></a>), you will save yourself a lot of trouble.
 See also <a class="xref" href="#faq-scope" title="A.4.14.">Q: A.4.14</a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="defconstant-similar"></a>5.5.1. Variable <a class="link" href="#defconstant-similar" title="5.5.1. Variable CUSTOM:*SUPPRESS-SIMILAR-CONSTANT-REDEFINITION-WARNING*"><code class="varname">CUSTOM:*SUPPRESS-SIMILAR-CONSTANT-REDEFINITION-WARNING*</code></a></h3></div></div></div><p>If the variable being defined by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defconstant.html" target="_top"><code class="function">DEFCONSTANT</code></a> is already bound to
 a value which is not <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eql.html" target="_top"><code class="function">EQL</code></a> to the new value, a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_warning.html" target="_top"><code class="classname">WARNING</code></a> is issued.
 If, however, the new value is <strong class="first"><em class="firstterm">visually similar
  <a id="visually-similar" class="indexterm"></a></em></strong>
 (prints to the same string, as is commonly the case when re-loading files)
 to the old one, the warning can be suppressed by setting
 <a class="link" href="#defconstant-similar" title="5.5.1. Variable CUSTOM:*SUPPRESS-SIMILAR-CONSTANT-REDEFINITION-WARNING*"><code class="varname">CUSTOM:*SUPPRESS-SIMILAR-CONSTANT-REDEFINITION-WARNING*</code></a> to a non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> value.</p><p>The initial value of <a class="link" href="#defconstant-similar" title="5.5.1. Variable CUSTOM:*SUPPRESS-SIMILAR-CONSTANT-REDEFINITION-WARNING*"><code class="varname">CUSTOM:*SUPPRESS-SIMILAR-CONSTANT-REDEFINITION-WARNING*</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="fcase"></a>5.6. Macro <a class="link" href="#fcase" title="5.6. Macro EXT:FCASE"><code class="function">EXT:FCASE</code></a></h2></div></div></div><p>This macro allows specifying the test for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_casecm_ccasecm_ecase.html" target="_top"><code class="function">CASE</code></a>, e.g.,
</p><pre class="programlisting">
(fcase string= (subseq foo 0 (position #\Space foo))
  ("first" 1)
  (("second" "two") 2)
  (("true" "yes") t)
  (otherwise nil))
</pre><p>
is the same as
</p><pre class="programlisting">
(let ((var (subseq foo 0 (position #\Space foo))))
  (cond ((string= var "first") 1)
        ((or (string= var "second") (string= var "two")) 2)
        ((or (string= var "true") (string= var "yes")) t)
        (t nil)))
</pre><p>
If you use a built-in <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a> test (see <a class="xref" href="#ht-test" title="18.4. Function HASH-TABLE-TEST">Section 18.4, “Function <code class="function">HASH-TABLE-TEST</code>”</a>)
as the test (e.g., <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_equal.html" target="_top"><code class="function">EQUAL</code></a> instead of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stringeqc_ng-not-lessp.html" target="_top"><code class="function">STRING=</code></a> above, but not a test
defined using <a class="link" href="#defhash" title="18.3. Macro EXT:DEFINE-HASH-TABLE-TEST"><code class="function">EXT:DEFINE-HASH-TABLE-TEST</code></a>), the compiler will be able to optimize the
<a class="link" href="#fcase" title="5.6. Macro EXT:FCASE"><code class="function">EXT:FCASE</code></a> form better than the corresponding <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_cond.html" target="_top"><code class="function">COND</code></a> form.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="xor"></a>5.7. Function <code class="function">EXT:XOR</code></h2></div></div></div><p>This function checks that exactly one of its arguments is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
 and, if this is the case, returns its value and index in the argument
 list as <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_m.html#multiple_values">multiple values</a>, otherwise returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="eq"></a>5.8. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a></h2></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a> compares <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>s and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_fixnum.html" target="_top"><code class="classname">FIXNUM</code></a>s as <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eql.html" target="_top"><code class="function">EQL</code></a> does.
 No unnecessary copies are made of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>s and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_number.html" target="_top"><code class="classname">NUMBER</code></a>s.
 Nevertheless, one should use <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eql.html" target="_top"><code class="function">EQL</code></a> as it is more portable across <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a>
 implementations.</p><p><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET</code></a> ((<em class="replaceable"><code>x</code></em> <em class="replaceable"><code>y</code></em>)) (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a> <em class="replaceable"><code>x</code></em> <em class="replaceable"><code>x</code></em>))</code> always
 returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> for any Lisp object <em class="replaceable"><code>y</code></em>.
 See also <a class="xref" href="#dffi-eq" title="Equality of foreign values">Equality of foreign values</a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="func"></a>5.9. Special Operator <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_function.html" target="_top"><code class="function">FUNCTION</code></a></h2></div></div></div><p><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_function.html" target="_top"><code class="function">FUNCTION</code></a> <em class="replaceable"><code>symbol</code></em>)</code> returns the local function
 definition established by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_fletcm_scm_macrolet.html" target="_top"><code class="function">FLET</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_fletcm_scm_macrolet.html" target="_top"><code class="function">LABELS</code></a>, if it exists, otherwise
 the global function definition.</p><p><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_special-operator-p.html" target="_top"><code class="function">SPECIAL-OPERATOR-P</code></a> <em class="replaceable"><code>symbol</code></em>)</code> returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> or
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.  If it returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>, then <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_symbol-function.html" target="_top"><code class="function">SYMBOL-FUNCTION</code></a>
  <em class="replaceable"><code>symbol</code></em>)</code> returns the (useless) special operator handler.</p></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="iteration"></a>Chapter 6. Iteration
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-6.html">[chap-6]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#loop">6.1. The LOOP Facility   sec_6-1</a></span></dt><dd><dl><dt><span class="section"><a href="#loop-termination">6.1.1. Mixing Termination Test Clauses   sec_6-1-4</a></span></dt><dt><span class="section"><a href="#loop-inter-var-finally">6.1.2. Iteration variables in the loop epilogue</a></span></dt><dt><span class="section"><a href="#loop-ansi">6.1.3. Backward Compatibility</a></span></dt></dl></dd><dt><span class="section"><a href="#iter-misc">6.2. Miscellaneous</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="loop"></a>6.1. The LOOP Facility
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_6-1.html">[sec_6-1]</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#loop-termination">6.1.1. Mixing Termination Test Clauses   sec_6-1-4</a></span></dt><dt><span class="section"><a href="#loop-inter-var-finally">6.1.2. Iteration variables in the loop epilogue</a></span></dt><dt><span class="section"><a href="#loop-ansi">6.1.3. Backward Compatibility</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="loop-termination"></a>6.1.1. Mixing Termination Test Clauses
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_6-1-4.html">[sec_6-1-4]</a></h3></div></div></div><p>Mixing termination test clauses with different default return
 values is not allowed because it is not specifed whether
 </p><pre class="programlisting">
(loop repeat 1 thereis nil never nil)
</pre><p> should return <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> (the default return value
 from <code class="literal">NEVER</code>) of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> (the default return value from
 <code class="literal">THEREIS</code>).</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="loop-inter-var-finally"></a>6.1.2. Iteration variables in the loop epilogue</h3></div></div></div><p>The standard is unambiguous in that the iteration variables do
 still exist in the
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_6-1-7-2.html"><code class="literal">FINALLY</code></a>
 clause, but <span class="strong"><strong>not</strong></span> as to what values these variables might have.
 Therefore the code which relies on the values of such variables, e.g.,
 </p><pre class="programlisting">(loop for x on y finally (return x))</pre><p>
 is inherently non-portable across <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> implementations,
 and should be avoided.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="loop-ansi"></a>6.1.3. Backward Compatibility</h3></div></div></div><p>There have been some tightening in the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_loop.html" target="_top"><code class="function">LOOP</code></a> syntax between
 <a class="xref" href="#CLtL2" title="Common Lisp: the Language (2nd Edition)">[<abbr class="abbrev">CLtL2</abbr>]</a> and [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>], e.g., the following form is legal in the
 former but not the latter:</p><pre class="programlisting">
(loop initially for i from 1 to 5 do (print i) finally return i)
</pre><p>
When <strong class="first"><em class="firstterm"><a class="link" href="#loop-ansi" title="6.1.3. Backward Compatibility"><code class="varname">CUSTOM:*LOOP-ANSI*</code></a></em></strong> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, such forms are still
accepted in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> but elicit a warning at macro-expansion time.
When <a class="link" href="#loop-ansi" title="6.1.3. Backward Compatibility"><code class="varname">CUSTOM:*LOOP-ANSI*</code></a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="iter-misc"></a>6.2. Miscellaneous</h2></div></div></div><p>The macros <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_dolist.html" target="_top"><code class="function">DOLIST</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_dotimes.html" target="_top"><code class="function">DOTIMES</code></a> establish a single binding for
the iteration variable and assign it on each iteration.</p></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="objects"></a>Chapter 7. Objects <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html">[chap-7]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#std-meth-combo">7.1. Standard Method Combination   sec_7-6-6-2</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="std-meth-combo"></a>7.1. Standard Method Combination
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_7-6-6-2.html">[sec_7-6-6-2]</a></h2></div></div></div><p>Generic function
 <strong class="first"><em class="firstterm"><a class="link" href="#no-prim"><code class="function">CLOS:NO-PRIMARY-METHOD</code></a><a id="no-prim" class="indexterm"></a></em></strong>
 (similar to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_no-_cable-method.html" target="_top"><code class="function">NO-APPLICABLE-METHOD</code></a>) is called when there is an
 applicable method but no applicable <span class="emphasis"><em>primary</em></span>
 method.</p><p>The default methods for <a class="link" href="#no-prim"><code class="function">CLOS:NO-PRIMARY-METHOD</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_no-_cable-method.html" target="_top"><code class="function">NO-APPLICABLE-METHOD</code></a> and
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_no-next-method.html" target="_top"><code class="function">NO-NEXT-METHOD</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a> an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> of type
 <strong class="first"><em class="firstterm"><a class="link" href="#meth-call-err"><code class="classname">CLOS:METHOD-CALL-ERROR</code></a>
  <a id="meth-call-err" class="indexterm"></a></em></strong>.
 You can find out more information about the error using functions
 <code class="function">CLOS:METHOD-CALL-ERROR-GENERIC-FUNCTION</code>,
 <code class="function">CLOS:METHOD-CALL-ERROR-ARGUMENT-LIST</code>, and
 (only for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_no-next-method.html" target="_top"><code class="function">NO-NEXT-METHOD</code></a>)
 <code class="function">CLOS:METHOD-CALL-ERROR-METHOD</code>.
 Moreover, when the generic function has only one <span class="emphasis"><em>dispatching
 argument</em></span>, (i.e., such an argument that not all the
 corresponding parameter specializers are <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>), an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> of type
 <strong class="first"><em class="firstterm"><a class="link" href="#meth-call-type-err"><code class="classname">CLOS:METHOD-CALL-TYPE-ERROR</code></a>
  <a id="meth-call-type-err" class="indexterm"></a></em></strong>
  is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed, additionally making <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_type-erro_xpected-type.html" target="_top"><code class="function">TYPE-ERROR-DATUM</code></a> and
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_type-erro_xpected-type.html" target="_top"><code class="function">TYPE-ERROR-EXPECTED-TYPE</code></a> available.</p></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="structures"></a>Chapter 8. Structures
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-8.html">[chap-8]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#defstruct-options">8.1. The options for <code class="function">DEFSTRUCT</code></a></span></dt><dd><dl><dt><span class="section"><a href="#defstruct-print-function">8.1.1. The <code class="constant">:PRINT-FUNCTION</code> option</a></span></dt><dt><span class="section"><a href="#defstruct-inherit">8.1.2. The <code class="constant">:INHERIT</code> option</a></span></dt></dl></dd><dt><span class="section"><a href="#defstruct-mop">8.2. The structure Meta-Object Protocol</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="defstruct-options"></a>8.1. The options for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defstruct.html" target="_top"><code class="function">DEFSTRUCT</code></a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#defstruct-print-function">8.1.1. The <code class="constant">:PRINT-FUNCTION</code> option</a></span></dt><dt><span class="section"><a href="#defstruct-inherit">8.1.2. The <code class="constant">:INHERIT</code> option</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="defstruct-print-function"></a>8.1.1. The <code class="constant">:PRINT-FUNCTION</code> option</h3></div></div></div><p>The <code class="constant">:PRINT-FUNCTION</code> option should contain a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-3.html">lambda expression</a>
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_lambda.html" target="_top"><code class="function">LAMBDA</code></a> (object stream depth) (declare (ignore depth)) ...)</code>
 This <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-3.html">lambda expression</a> names a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a> whose task is to output the
 external representation of the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_structure-object.html" target="_top"><code class="classname">STRUCTURE-OBJECT</code></a> <em class="replaceable"><code>object</code></em> onto the
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> <em class="replaceable"><code>stream</code></em>. This may be done by outputting text onto the
 stream using <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_write-char.html" target="_top"><code class="function">WRITE-CHAR</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_write-str_m_write-line.html" target="_top"><code class="function">WRITE-STRING</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">WRITE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">PRIN1</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">PRINC</code></a>,
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">PRINT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">PPRINT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> and the like.
 The following rules must be obeyed:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The value of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-escapest.html" target="_top"><code class="varname">*PRINT-ESCAPE*</code></a> must be
  respected.</li><li class="listitem">The treatment of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-prettyst.html" target="_top"><code class="varname">*PRINT-PRETTY*</code></a> is up to you.
 </li><li class="listitem">The value of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-circlest.html" target="_top"><code class="varname">*PRINT-CIRCLE*</code></a> need not be
  respected.  This is managed by the system.  (But the print-circle
  mechanism handles only those objects that are direct or indirect
  components of the structure.)</li><li class="listitem">The value of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-l_int-lengthst.html" target="_top"><code class="varname">*PRINT-LEVEL*</code></a> is respected by
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">WRITE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">PRIN1</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">PRINC</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">PRINT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">PPRINT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> instructions
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-4-1.html"><code class="literal">~A</code></a>, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-4-2.html"><code class="literal">~S</code></a>, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-4-3.html"><code class="literal">~W</code></a>, and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> instructions
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-2-1.html"><code class="literal">~R</code></a>, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-2-2.html"><code class="literal">~D</code></a>, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-2-3.html"><code class="literal">~B</code></a>, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-2-4.html"><code class="literal">~O</code></a>, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-2-5.html"><code class="literal">~X</code></a>, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-3-1.html"><code class="literal">~F</code></a>,
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-3-2.html"><code class="literal">~E</code></a>, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-3-3.html"><code class="literal">~G</code></a>, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-3-4.html"><code class="literal">~$</code></a> with not-numerical arguments.
  Therefore the print-level mechanism works automatically if only these
  functions are used for outputting objects and if they are not called
  on objects with nesting level &gt; 1. (The print-level mechanism does
  not recognize how many parentheses you have output. It only counts how
  many times it was called recursively.)</li><li class="listitem">The value of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-l_int-lengthst.html" target="_top"><code class="varname">*PRINT-LENGTH*</code></a> must be respected,
  especially if you are outputting an arbitrary number of components.
 </li><li class="listitem">The value of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-readablyst.html" target="_top"><code class="varname">*PRINT-READABLY*</code></a> must be
  respected. Remember that the values of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-escapest.html" target="_top"><code class="varname">*PRINT-ESCAPE*</code></a>,
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-l_int-lengthst.html" target="_top"><code class="varname">*PRINT-LEVEL*</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-l_int-lengthst.html" target="_top"><code class="varname">*PRINT-LENGTH*</code></a> are ignored if
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-readablyst.html" target="_top"><code class="varname">*PRINT-READABLY*</code></a> is true.  The value of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-readablyst.html" target="_top"><code class="varname">*PRINT-READABLY*</code></a> is
  respected by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_print-unr_dable-object.html" target="_top"><code class="function">PRINT-UNREADABLE-OBJECT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">WRITE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">PRIN1</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">PRINC</code></a>,
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">PRINT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">PPRINT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> instructions <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-4-1.html"><code class="literal">~A</code></a>, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-4-2.html"><code class="literal">~S</code></a>,
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-4-3.html"><code class="literal">~W</code></a>, and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> instructions <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-2-1.html"><code class="literal">~R</code></a>, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-2-2.html"><code class="literal">~D</code></a>,
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-2-3.html"><code class="literal">~B</code></a>, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-2-4.html"><code class="literal">~O</code></a>, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-2-5.html"><code class="literal">~X</code></a>, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-3-1.html"><code class="literal">~F</code></a>, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-3-2.html"><code class="literal">~E</code></a>,
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-3-3.html"><code class="literal">~G</code></a>, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-3-4.html"><code class="literal">~$</code></a> with not-numerical arguments.  Therefore
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-readablyst.html" target="_top"><code class="varname">*PRINT-READABLY*</code></a> will be respected automatically if only these
  functions are used for printing objects.</li><li class="listitem">You need not worry about the values of
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-b_rint-radixst.html" target="_top"><code class="varname">*PRINT-BASE*</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-b_rint-radixst.html" target="_top"><code class="varname">*PRINT-RADIX*</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-casest.html" target="_top"><code class="varname">*PRINT-CASE*</code></a>,
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-gensymst.html" target="_top"><code class="varname">*PRINT-GENSYM*</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-arrayst.html" target="_top"><code class="varname">*PRINT-ARRAY*</code></a>, <a class="link" href="#pr-closure" title="Variable CUSTOM:*PRINT-CLOSURE*"><code class="varname">CUSTOM:*PRINT-CLOSURE*</code></a>,
  <a class="link" href="#pr-rpars" title="Variable CUSTOM:*PRINT-RPARS*"><code class="varname">CUSTOM:*PRINT-RPARS*</code></a>, <a class="link" href="#pr-indent" title="Variable CUSTOM:*PRINT-INDENT-LISTS*"><code class="varname">CUSTOM:*PRINT-INDENT-LISTS*</code></a>.</li></ul></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="defstruct-inherit"></a>8.1.2. The <code class="constant">:INHERIT</code> option</h3></div></div></div><p>The <code class="constant">:INHERIT</code> option is exactly like <code class="constant">:INCLUDE</code> except that it
 does not create new accessors for the inherited slots (this is a
 <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> extension).</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="defstruct-mop"></a>8.2. The structure <a class="link" href="#mop-chap" title="Chapter 29. Meta-Object Protocol">Meta-Object Protocol</a></h2></div></div></div><p>The following functions accept a structure <em class="replaceable"><code>name</code></em> as the only argument.
 If <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defstruct.html" target="_top"><code class="function">DEFSTRUCT</code></a> was given the <code class="constant">:TYPE</code> option (i.e., <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defstruct.html" target="_top"><code class="function">DEFSTRUCT</code></a> did
 <span class="strong"><strong>not</strong></span> define a new type), then <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_find-class.html" target="_top"><code class="function">FIND-CLASS</code></a> <em class="replaceable"><code>name</code></em>)</code>
 fails (and the regular <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> <a class="link" href="#mop-chap" title="Chapter 29. Meta-Object Protocol">Meta-Object Protocol</a> is not applicable), but these
 functions still work.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="function">EXT:STRUCTURE-SLOTS</code></span></dt><dd>Return the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s.
</dd><dt><span class="term"><code class="function">EXT:STRUCTURE-DIRECT-SLOTS</code></span></dt><dd>Return the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s.
</dd><dt><span class="term"><code class="function">EXT:STRUCTURE-KEYWORD-CONSTRUCTOR</code></span></dt><dd>Return the name (a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>) of the keyword
   constructor function for the structure, or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if the structure has
   no keyword constructor.</dd><dt><span class="term"><code class="function">EXT:STRUCTURE-BOA-CONSTRUCTORS</code></span></dt><dd>Return the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of names (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>s)
  of BOA constructors for the structure.</dd><dt><span class="term"><code class="function">EXT:STRUCTURE-COPIER</code></span></dt><dd>Return the name (a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>) of the copier for the
   structure.</dd><dt><span class="term"><code class="function">EXT:STRUCTURE-PREDICATE</code></span></dt><dd>Return the name (a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>) of the predicate for
   the structure.</dd></dl></div></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="conditions"></a>Chapter 9. Conditions
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-9.html">[chap-9]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#cond-nl">9.1. Embedded Newlines in Condition Reports   sec_9-1-3-1-3</a></span></dt><dt><span class="section"><a href="#cond-fname">9.2. Mentioning Containing Function in   Condition Reports sec_9-1-3-1-5</a></span></dt><dt><span class="section"><a href="#restarts">9.3. Interfaces to Restarts   sec_9-1-4-2-2</a></span></dt><dt><span class="section"><a href="#assertions">9.4. Assertions   sec_9-1-5</a></span></dt></dl></div><p>When an error occurred, you are in a break loop. You can evaluate
 forms as usual. The <a href="impnotes.html#debugger-main-deb-step" class="olink"><span class="command"><strong>help</strong></span></a> command (or help key if there is one) lists
 the available <a class="link" href="#debugger" title="25.2. Debugging Utilities sec_25-1-2">debugger</a> commands.</p><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="cond-nl"></a>9.1. Embedded Newlines in Condition Reports
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_9-1-3-1-3.html">[sec_9-1-3-1-3]</a></h2></div></div></div><p>The error message prefix for the first line is <span class="quote">“<span class="quote">*** - </span>”</span>.
 All subsequent lines are indented by 6 characters.
 Long lines are broken on <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-1-4-7.html">whitespace</a>
 (see <a class="xref" href="#fill-stream" title="30.8. Class EXT:FILL-STREAM">Section 30.8, “Class <code class="classname">EXT:FILL-STREAM</code>”</a>).</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="cond-fname"></a>9.2. Mentioning Containing Function in
  Condition Reports <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_9-1-3-1-5.html">[sec_9-1-3-1-5]</a></h2></div></div></div><p>Contrary to the recommendation of the standard, <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> usually
 does print the name of the containing function to simplify debugging
 in batch mode, see <a href="impnotes.html#exit-on-error" class="olink"><code class="function">EXT:EXIT-ON-ERROR</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="restarts"></a>9.3. Interfaces to Restarts
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_9-1-4-2-2.html">[sec_9-1-4-2-2]</a></h2></div></div></div><p><a id="restart-case"></a><strong>Macro <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_restart-case.html" target="_top"><code class="function">RESTART-CASE</code></a>. </strong>In <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_restart-case.html" target="_top"><code class="function">RESTART-CASE</code></a> <em class="replaceable"><code>form</code></em> {<em class="replaceable"><code>restart-clause</code></em>}*)</code>,
  the argument list can also be specified after the keyword/value pairs
  instead of before them, i.e., each <em class="replaceable"><code>restart-clause</code></em> can be either
  <code class="code">(<code class="varname">restart-name</code> <a href="impnotes.html#script-exec" class="olink"><code class="varname">EXT:*ARGS*</code></a>
   {<em class="replaceable"><code>keyword-value-pair</code></em>}* {<em class="replaceable"><code>form</code></em>}*)</code>
  or <code class="code">(<em class="replaceable"><code>restart-name</code></em>
   {<em class="replaceable"><code>keyword-value-pair</code></em>}* <a href="impnotes.html#script-exec" class="olink"><code class="varname">EXT:*ARGS*</code></a> {<em class="replaceable"><code>form</code></em>}*)</code>.
</p><p><a id="with-restarts"></a><strong>Macro <a class="link" href="#with-restarts" title="Macro EXT:WITH-RESTARTS"><code class="function">EXT:WITH-RESTARTS</code></a>. </strong>The macro <a class="link" href="#with-restarts" title="Macro EXT:WITH-RESTARTS"><code class="function">EXT:WITH-RESTARTS</code></a> is like <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_restart-case.html" target="_top"><code class="function">RESTART-CASE</code></a>, except that the
 forms are specified after the restart clauses instead of before them,
 and the restarts created are not implicitly associated with any <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_condition.html" target="_top"><code class="classname">CONDITION</code></a>.
 <code class="code">(<a class="link" href="#with-restarts" title="Macro EXT:WITH-RESTARTS"><code class="function">EXT:WITH-RESTARTS</code></a> ({<em class="replaceable"><code>restart-clause</code></em>}*) {<em class="replaceable"><code>form</code></em>}*)</code> is
 therefore equivalent to <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_restart-case.html" target="_top"><code class="function">RESTART-CASE</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_progn.html" target="_top"><code class="function">PROGN</code></a> {<em class="replaceable"><code>form</code></em>}*)
 {<em class="replaceable"><code>restart-clause</code></em>}*)</code>.</p><p><a id="compute-restarts"></a><strong>Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compute-restarts.html" target="_top"><code class="function">COMPUTE-RESTARTS</code></a>. </strong><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compute-restarts.html" target="_top"><code class="function">COMPUTE-RESTARTS</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_find-restart.html" target="_top"><code class="function">FIND-RESTART</code></a> behave as specified in
 [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>]: If the optional <em class="replaceable"><code>condition</code></em> argument is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>,
 only <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_restart.html" target="_top"><code class="classname">RESTART</code></a>s associated with that <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_condition.html" target="_top"><code class="classname">CONDITION</code></a>
 and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_restart.html" target="_top"><code class="classname">RESTART</code></a>s associated with no <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_condition.html" target="_top"><code class="classname">CONDITION</code></a> at all are considered.
 Therefore the effect of associating a restart to a condition is not to
 activate it, but to hide it from other conditions.
 This makes the syntax-dependent implicit association performed by
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_restart-case.html" target="_top"><code class="function">RESTART-CASE</code></a> nearly obsolete.</p><p><a id="muffle-cerrors"></a><strong>Macro <a class="link" href="#muffle-cerrors" title="Macro EXT:MUFFLE-CERRORS"><code class="function">EXT:MUFFLE-CERRORS</code></a>. </strong>The macro <code class="code">(<a class="link" href="#muffle-cerrors" title="Macro EXT:MUFFLE-CERRORS"><code class="function">EXT:MUFFLE-CERRORS</code></a> {<em class="replaceable"><code>form</code></em>}*)</code>
 executes the <em class="replaceable"><code>form</code></em>s; when a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#continuable">continuable</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> occurs whose <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_abortcm_c_cm_use-value.html" target="_top"><code class="function">CONTINUE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_restart.html" target="_top"><code class="classname">RESTART</code></a>
 can be invoked non-interactively (this includes all <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#continuable">continuable</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>s signaled
 by the function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_cerror.html" target="_top"><code class="function">CERROR</code></a>), no message is printed, instead, the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_abortcm_c_cm_use-value.html" target="_top"><code class="function">CONTINUE</code></a>
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_restart.html" target="_top"><code class="classname">RESTART</code></a> is invoked.</p><p><a id="appease-cerrors"></a><strong>Macro <a href="impnotes.html#appease-cerrors" class="olink"><code class="function">EXT:APPEASE-CERRORS</code></a>. </strong>The macro <code class="code">(<a href="impnotes.html#appease-cerrors" class="olink"><code class="function">EXT:APPEASE-CERRORS</code></a> {<em class="replaceable"><code>form</code></em>}*)</code>
 executes the <em class="replaceable"><code>form</code></em>s; when a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#continuable">continuable</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> occurs whose <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_abortcm_c_cm_use-value.html" target="_top"><code class="function">CONTINUE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_restart.html" target="_top"><code class="classname">RESTART</code></a>
 can be invoked non-interactively (this includes all <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#continuable">continuable</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>s <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed
 by the function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_cerror.html" target="_top"><code class="function">CERROR</code></a>), it is reported as a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_warning.html" target="_top"><code class="classname">WARNING</code></a>, and the
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_abortcm_c_cm_use-value.html" target="_top"><code class="function">CONTINUE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_restart.html" target="_top"><code class="classname">RESTART</code></a> is invoked.</p><p><a id="abort-on-error"></a><strong>Macro <a href="impnotes.html#abort-on-error" class="olink"><code class="function">EXT:ABORT-ON-ERROR</code></a>. </strong>The macro <code class="code">(<a href="impnotes.html#abort-on-error" class="olink"><code class="function">EXT:ABORT-ON-ERROR</code></a> {<em class="replaceable"><code>form</code></em>}*)</code>
 executes the <em class="replaceable"><code>form</code></em>s; when an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> occurs, or when a <span class="keycap"><strong>Control</strong></span>+<span class="keysym">C</span>
 interrupt occurs, the error message is printed and the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/res_abort.html" target="_top"><code class="function">ABORT</code></a>
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_restart.html" target="_top"><code class="classname">RESTART</code></a> is invoked.</p><p><a id="exit-on-error"></a><strong>Macro <a href="impnotes.html#exit-on-error" class="olink"><code class="function">EXT:EXIT-ON-ERROR</code></a>. </strong>The macro <code class="code">(<a href="impnotes.html#exit-on-error" class="olink"><code class="function">EXT:EXIT-ON-ERROR</code></a> {<em class="replaceable"><code>form</code></em>}*)</code>
 executes the <em class="replaceable"><code>form</code></em>s; when an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> occurs, or when a <span class="keycap"><strong>Control</strong></span>+<span class="keysym">C</span>
 interrupt occurs, the error message is printed and <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> terminates
 with an error status.</p><p><a id="err-pr-bt"></a><strong>Variable <a href="impnotes.html#err-pr-bt" class="olink"><code class="varname">CUSTOM:*REPORT-ERROR-PRINT-BACKTRACE*</code></a>. </strong>When this variable is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> the error message printed by
 <a href="impnotes.html#abort-on-error" class="olink"><code class="function">EXT:ABORT-ON-ERROR</code></a> and <a href="impnotes.html#exit-on-error" class="olink"><code class="function">EXT:EXIT-ON-ERROR</code></a> includes the <a class="link" href="#backtrace"><span class="command"><strong>backtrace</strong></span></a> (stack).
</p><p><a id="global-handler"></a><strong>Function <a href="impnotes.html#global-handler" class="olink"><code class="function">EXT:SET-GLOBAL-HANDLER</code></a>. </strong>The function <code class="code">(<a href="impnotes.html#global-handler" class="olink"><code class="function">EXT:SET-GLOBAL-HANDLER</code></a> <em class="replaceable"><code>condition</code></em> handler)</code>
 establishes a global handler for the <em class="replaceable"><code>condition</code></em>.
 The <em class="replaceable"><code>handler</code></em> should be <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_funcall.html" target="_top"><code class="function">FUNCALL</code></a>able (a
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a> or a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a>).
 If it returns, the next applicable handler is invoked, so if you do
 <span class="strong"><strong>not</strong></span> want to land in the <a class="link" href="#debugger" title="25.2. Debugging Utilities sec_25-1-2">debugger</a>, it should <span class="strong"><strong>not</strong></span> return.
 E.g., the option <code class="option"><a href="clisp.html#opt-on-error" class="olink">-on-error</a></code> <code class="option">abort</code> and the macro
 <a href="impnotes.html#abort-on-error" class="olink"><code class="function">EXT:ABORT-ON-ERROR</code></a> are implemented by installing the following handler:
 </p><pre class="programlisting">(defun sys::abortonerror (condition)
  (sys::report-error condition)
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_invoke-restart.html" target="_top"><code class="function">INVOKE-RESTART</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_find-restart.html" target="_top"><code class="function">FIND-RESTART</code></a> '<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_abortcm_c_cm_use-value.html" target="_top"><code class="function">ABORT</code></a> condition)))</pre><p>
 When <em class="replaceable"><code>handler</code></em> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the handler
 for <em class="replaceable"><code>condition</code></em> is removed and returned.
 When <em class="replaceable"><code>condition</code></em> is also <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, all global handlers are removed and returned
 as a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>, which can then be passed to <a href="impnotes.html#global-handler" class="olink"><code class="function">EXT:SET-GLOBAL-HANDLER</code></a> as the
 first argument and the handlers re-established.</p><p><a id="without-global-handlers"></a><strong>Macro <a href="impnotes.html#without-global-handlers" class="olink"><code class="function">EXT:WITHOUT-GLOBAL-HANDLERS</code></a>. </strong>The macro <code class="code">(<a href="impnotes.html#without-global-handlers" class="olink"><code class="function">EXT:WITHOUT-GLOBAL-HANDLERS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a>
  <em class="replaceable"><code>body</code></em>)</code> removes all global handlers by <code class="code">(<a href="impnotes.html#global-handler" class="olink"><code class="function">EXT:SET-GLOBAL-HANDLER</code></a>
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>)</code>, executes <em class="replaceable"><code>body</code></em> (where unhandled conditions now
 invoke the <a class="link" href="#debugger" title="25.2. Debugging Utilities sec_25-1-2">debugger</a>), and then restores the handlers.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="assertions"></a>9.4. Assertions
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_9-1-5.html">[sec_9-1-5]</a></h2></div></div></div><p>The prompt for replacement values (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_restart.html" target="_top"><code class="classname">RESTART</code></a>s <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/res_store-value.html" target="_top"><code class="function">STORE-VALUE</code></a>,
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/res_use-value.html" target="_top"><code class="function">USE-VALUE</code></a> et al) is terminated with <a class="link" href="#prompt-finish"><code class="varname">CUSTOM:*PROMPT-FINISH*</code></a> to indicate that
the value entered is treated as usual for the Lisp <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-1.html">read-eval-print loop</a>, i.e., it is
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eval.html" target="_top"><code class="function">EVAL</code></a>uated.</p></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="symbols"></a>Chapter 10. Symbols <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-10.html">[chap-10]</a></h2></div></div></div><p>No notes.</p></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="packages"></a>Chapter 11. Packages
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-11.html">[chap-11]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#pack-intro">11.1. Introduction to Packages   sec_11-1-1</a></span></dt><dd><dl><dt><span class="section"><a href="#make-pack">11.1.1. Function <code class="function">MAKE-PACKAGE</code></a></span></dt><dt><span class="section"><a href="#defpack">11.1.2. Macro <code class="function">DEFPACKAGE</code></a></span></dt><dt><span class="section"><a href="#re-export">11.1.3. Function <code class="function">EXT:RE-EXPORT</code></a></span></dt><dt><span class="section"><a href="#pack-inverted">11.1.4. Function <code class="function">EXT:PACKAGE-CASE-INVERTED-P</code></a></span></dt><dt><span class="section"><a href="#pack-sensitive">11.1.5. Function <code class="function">EXT:PACKAGE-CASE-SENSITIVE-P</code></a></span></dt></dl></dd><dt><span class="section"><a href="#pack-lock">11.2. Constraints on the <strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong> Package   for Conforming Programs - package locking  sec_11-1-2-1-2</a></span></dt><dt><span class="section"><a href="#clupack">11.3. The   <strong class="package"><span class="quote">“<span class="quote">COMMON-LISP-USER</span>”</span></strong> Package   sec_11-1-2-2</a></span></dt><dt><span class="section"><a href="#imppack">11.4. Implementation-Defined Packages   sec_11-1-2-4</a></span></dt><dt><span class="section"><a href="#package-case">11.5. Package Case-Sensitivity</a></span></dt><dd><dl><dt><span class="section"><a href="#cs-clu">11.5.1. User Package for the Case-sensitive World</a></span></dt><dt><span class="section"><a href="#cs-pack-name">11.5.2. Package Names</a></span></dt><dt><span class="section"><a href="#cs-gensym-kwd">11.5.3. Gensyms and Keywords</a></span></dt><dt><span class="section"><a href="#case-sensitive-migration">11.5.4. Migration Tips</a></span></dt><dt><span class="section"><a href="#case-sensitive-startup">11.5.5. Using case-sensitive packages by default</a></span></dt></dl></dd></dl></div><div class="variablelist"><p class="title"><strong>The [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] packages present in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a></strong></p><dl class="variablelist"><dt><span class="term"><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong></a></span></dt><dd>with the nicknames <strong class="package"><span class="quote">“<span class="quote">CL</span>”</span></strong>
    and <strong class="package"><span class="quote">“<span class="quote">LISP</span>”</span></strong></dd><dt><span class="term"><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-2.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP-USER</span>”</span></strong></a></span></dt><dd>with the nicknames <strong class="package"><span class="quote">“<span class="quote">CL-USER</span>”</span></strong>
    and <strong class="package"><span class="quote">“<span class="quote">USER</span>”</span></strong></dd><dt><span class="term"><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-3.html"><strong class="package"><span class="quote">“<span class="quote">KEYWORD</span>”</span></strong></a></span></dt><dd>with no nicknames
 </dd></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="pack-intro"></a>11.1. Introduction to Packages
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-1.html">[sec_11-1-1]</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#make-pack">11.1.1. Function <code class="function">MAKE-PACKAGE</code></a></span></dt><dt><span class="section"><a href="#defpack">11.1.2. Macro <code class="function">DEFPACKAGE</code></a></span></dt><dt><span class="section"><a href="#re-export">11.1.3. Function <code class="function">EXT:RE-EXPORT</code></a></span></dt><dt><span class="section"><a href="#pack-inverted">11.1.4. Function <code class="function">EXT:PACKAGE-CASE-INVERTED-P</code></a></span></dt><dt><span class="section"><a href="#pack-sensitive">11.1.5. Function <code class="function">EXT:PACKAGE-CASE-SENSITIVE-P</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="make-pack"></a>11.1.1. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-package.html" target="_top"><code class="function">MAKE-PACKAGE</code></a></h3></div></div></div><p>The default value of the <code class="constant">:USE</code> argument is
 <span class="data"><code class="literal">(<a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong></a>)</code></span>.</p><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-package.html" target="_top"><code class="function">MAKE-PACKAGE</code></a> accepts additional keyword arguments
 <a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-SENSITIVE</code></a> and <a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-INVERTED</code></a> (but <span class="strong"><strong>not</strong></span> <a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:MODERN</code></a>!)
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="defpack"></a>11.1.2. Macro <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defpackage.html" target="_top"><code class="function">DEFPACKAGE</code></a></h3></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defpackage.html" target="_top"><code class="function">DEFPACKAGE</code></a> accepts additional options <a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-SENSITIVE</code></a>,
 <a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-INVERTED</code></a>, and <a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:MODERN</code></a>.</p><p>When the package being defined already exists, it is modified as
 follows (and in this order):</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-SENSITIVE</code></a></span></dt><dd>adjusted with <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="link" href="#pack-sensitive" title="11.1.5. Function EXT:PACKAGE-CASE-SENSITIVE-P"><code class="function">EXT:PACKAGE-CASE-SENSITIVE-P</code></a>)</code>
     (with a warning)</dd><dt><span class="term"><a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-INVERTED</code></a></span></dt><dd>adjusted with <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="link" href="#pack-inverted" title="11.1.4. Function EXT:PACKAGE-CASE-INVERTED-P"><code class="function">EXT:PACKAGE-CASE-INVERTED-P</code></a>)</code>
     (with a warning)</dd><dt><span class="term"><a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:MODERN</code></a></span></dt><dd><p>if <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong></a> is being used, it is un-used and
     <a href="impnotes.html#package-case" class="olink"><strong class="package"><span class="quote">“<span class="quote">CS-COMMON-LISP</span>”</span></strong></a> is used instead; also, <a href="impnotes.html#package-case" class="olink"><strong class="package"><span class="quote">“<span class="quote">CS-COMMON-LISP</span>”</span></strong></a> is used instead of <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong></a>
     throughout the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defpackage.html" target="_top"><code class="function">DEFPACKAGE</code></a> form, e.g.,</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defpackage.html" target="_top"><code class="function">DEFPACKAGE</code></a> "FOO"
  (<a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:MODERN</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>)
  (<code class="constant">:USE</code> "COMMON-LISP" "EXT"))
</pre><p>is equivalent to</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defpackage.html" target="_top"><code class="function">DEFPACKAGE</code></a> "FOO"
  (<a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-SENSITIVE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>)
  (<a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-INVERTED</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>)
  (<code class="constant">:USE</code> "CS-COMMON-LISP" "EXT"))
</pre><p class="simpara"><code class="code">(<a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:MODERN</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>)</code> reverts the
      effects of <code class="code">(<a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:MODERN</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>)</code>.</p></dd><dt><span class="term"><code class="constant">:NICKNAMES</code></span></dt><dd>adjusted with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_rename-package.html" target="_top"><code class="function">RENAME-PACKAGE</code></a>
  </dd><dt><span class="term"><code class="constant">:DOCUMENTATION</code></span></dt><dd>reset to the new value with <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>
      <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_doc_umentationcp.html" target="_top"><code class="function">DOCUMENTATION</code></a>)</code></dd><dt><span class="term"><code class="constant">:SHADOW</code></span></dt><dd>adjusted with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_shadow.html" target="_top"><code class="function">SHADOW</code></a>
  </dd><dt><span class="term"><code class="constant">:SHADOWING-IMPORT-FROM</code></span></dt><dd>adjusted with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_shadowing-import.html" target="_top"><code class="function">SHADOWING-IMPORT</code></a>
  </dd><dt><span class="term"><code class="constant">:USE</code></span></dt><dd>adjusted with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_use-package.html" target="_top"><code class="function">USE-PACKAGE</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_unuse-package.html" target="_top"><code class="function">UNUSE-PACKAGE</code></a>
  </dd><dt><span class="term"><code class="constant">:IMPORT-FROM</code></span></dt><dd>adjusted with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_import.html" target="_top"><code class="function">IMPORT</code></a>
  </dd><dt><span class="term"><code class="constant">:INTERN</code></span></dt><dd>adjusted with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_intern.html" target="_top"><code class="function">INTERN</code></a> (but <span class="strong"><strong>not</strong></span> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_unintern.html" target="_top"><code class="function">UNINTERN</code></a>)
  </dd><dt><span class="term"><code class="constant">:EXPORT</code></span></dt><dd>adjusted with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_intern.html" target="_top"><code class="function">INTERN</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_export.html" target="_top"><code class="function">EXPORT</code></a> (but <span class="strong"><strong>not</strong></span>
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_unexport.html" target="_top"><code class="function">UNEXPORT</code></a>)</dd><dt><span class="term"><code class="constant">:SIZE</code></span></dt><dd>ignored</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="re-export"></a>11.1.3. Function <a class="link" href="#re-export" title="11.1.3. Function EXT:RE-EXPORT"><code class="function">EXT:RE-EXPORT</code></a></h3></div></div></div><p>The function <code class="code">(<a class="link" href="#re-export" title="11.1.3. Function EXT:RE-EXPORT"><code class="function">EXT:RE-EXPORT</code></a> <em class="replaceable"><code>FROM-PACK</code></em>
  <em class="replaceable"><code>TO-PACK</code></em>)</code> re-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_export.html" target="_top"><code class="function">EXPORT</code></a>s all external
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>s from <em class="replaceable"><code>FROM-PACK</code></em> also from
 <em class="replaceable"><code>TO-PACK</code></em>, provided it already uses
 <em class="replaceable"><code>FROM-PACK</code></em>; and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> otherwise.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="pack-inverted"></a>11.1.4. Function <a class="link" href="#pack-inverted" title="11.1.4. Function EXT:PACKAGE-CASE-INVERTED-P"><code class="function">EXT:PACKAGE-CASE-INVERTED-P</code></a></h3></div></div></div><p>Returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> if the argument is a
  <a class="link" href="#pack-case-inverted">case-inverted package</a>.
  This function is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>able, although it is probably not a good idea
  to change the case-inverted status of an existing package.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="pack-sensitive"></a>11.1.5. Function <a class="link" href="#pack-sensitive" title="11.1.5. Function EXT:PACKAGE-CASE-SENSITIVE-P"><code class="function">EXT:PACKAGE-CASE-SENSITIVE-P</code></a></h3></div></div></div><p>Returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> if the argument is a <a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-SENSITIVE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_package.html" target="_top"><code class="classname">PACKAGE</code></a>.
  This function is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>able, although it is probably not a good idea
  to change the case-sensitive status of an existing package.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="pack-lock"></a>11.2. Constraints on the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong></a> Package
  for Conforming Programs - package locking
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1-2.html">[sec_11-1-2-1-2]</a></h2></div></div></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>Locking discussed in this section has nothing to do with
  <a class="link" href="#mutex-lock"><code class="function">MT:MUTEX-LOCK</code></a>.</p></div><p><strong>Function <strong class="first"><em class="firstterm"><a class="link" href="#pack-lock" title="11.2. Constraints on the “COMMON-LISP” Package for Conforming Programs - package locking sec_11-1-2-1-2"><code class="function">EXT:PACKAGE-LOCK</code></a>
   <a id="pack-lock-f" class="indexterm"></a></em></strong>. </strong>Packages can be <span class="quote">“<span class="quote">locked</span>”</span>.
When a package is locked, attempts to change its symbol table or
redefine its symbols (as <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defun.html" target="_top"><code class="function">DEFUN</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmacro.html" target="_top"><code class="function">DEFMACRO</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defparametercm_defvar.html" target="_top"><code class="function">DEFVAR</code></a>,
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defparametercm_defvar.html" target="_top"><code class="function">DEFPARAMETER</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defconstant.html" target="_top"><code class="function">DEFCONSTANT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_deftype.html" target="_top"><code class="function">DEFTYPE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_declaration.html" target="_top"><code class="literal">DECLARATION</code></a>)
result in a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#continuable">continuable</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> (continuing overrides locking for this operation).
When <a class="link" href="#suppress-check-redef" title="Variable CUSTOM:*SUPPRESS-CHECK-REDEFINITION*"><code class="varname">CUSTOM:*SUPPRESS-CHECK-REDEFINITION*</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> (<span class="strong"><strong>not</strong></span> a good idea!), the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>
is not <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed for redefine operations.
Function <code class="code">(<a class="link" href="#pack-lock" title="11.2. Constraints on the “COMMON-LISP” Package for Conforming Programs - package locking sec_11-1-2-1-2"><code class="function">EXT:PACKAGE-LOCK</code></a> <em class="replaceable"><code>package</code></em>)</code>
returns the generalized boolean indicating whether the <em class="replaceable"><code>package</code></em> is locked.
A package (or a list thereof) can be locked using <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>
 (<a class="link" href="#pack-lock" title="11.2. Constraints on the “COMMON-LISP” Package for Conforming Programs - package locking sec_11-1-2-1-2"><code class="function">EXT:PACKAGE-LOCK</code></a> <em class="replaceable"><code>package-or-list</code></em>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>)</code>.
<a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> locks its system packages (specified in the variable
<a class="link" href="#pack-lock" title="11.2. Constraints on the “COMMON-LISP” Package for Conforming Programs - package locking sec_11-1-2-1-2"><code class="varname">CUSTOM:*SYSTEM-PACKAGE-LIST*</code></a>).</p><p><strong>Macro <a class="link" href="#without-pack-lock"><code class="function">EXT:WITHOUT-PACKAGE-LOCK</code></a>. </strong>If you want to evaluate some forms with certain packages unlocked,
 you can use
 <strong class="first"><em class="firstterm"><a class="link" href="#without-pack-lock"><code class="function">EXT:WITHOUT-PACKAGE-LOCK</code></a>
  <a id="without-pack-lock" class="indexterm"></a></em></strong>:
</p><pre class="programlisting">
(<a class="link" href="#without-pack-lock"><code class="function">EXT:WITHOUT-PACKAGE-LOCK</code></a> (<a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong></a> <a class="link" href="#ext-pac"><strong class="package"><span class="quote">“<span class="quote">EXT</span>”</span></strong></a> <a class="link" href="#classes" title="4.2. Classes sec_4-3"><strong class="package"><span class="quote">“<span class="quote">CLOS</span>”</span></strong></a>)
  (defun restart () ...))
</pre><p>
or
</p><pre class="programlisting">
(<a class="link" href="#without-pack-lock"><code class="function">EXT:WITHOUT-PACKAGE-LOCK</code></a> (<a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong></a>) (trace read-line))
</pre><p>
<code class="code">(<a class="link" href="#without-pack-lock"><code class="function">EXT:WITHOUT-PACKAGE-LOCK</code></a> () ...)</code>
temporarily unlocks all packages in <a class="link" href="#pack-lock" title="11.2. Constraints on the “COMMON-LISP” Package for Conforming Programs - package locking sec_11-1-2-1-2"><code class="varname">CUSTOM:*SYSTEM-PACKAGE-LIST*</code></a>.</p><p><strong>Variable <a class="link" href="#pack-lock" title="11.2. Constraints on the “COMMON-LISP” Package for Conforming Programs - package locking sec_11-1-2-1-2"><code class="varname">CUSTOM:*SYSTEM-PACKAGE-LIST*</code></a>. </strong>This variable specifies the default packages to be locked by <a href="impnotes.html#image" class="olink"><code class="function">EXT:SAVEINITMEM</code></a>
 and unlocked by <a class="link" href="#without-pack-lock"><code class="function">EXT:WITHOUT-PACKAGE-LOCK</code></a> as a list of package names.
 You may add names to this list, e.g., a module will add its package,
 but you should <span class="strong"><strong>not</strong></span> remove <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> internal packages from this list.
</p><p><strong>Discussion - see also
  <a class="ulink" href="https://groups.google.com/forum/#!msg/comp.lang.lisp/L1xRYHBY2Gs/qjVNn9pEeNgJ" target="_top">the USENET posting</a> by
  <span class="author"><span class="firstname">Steven M.</span> <span class="surname">Haflich</span></span>. </strong>This should prevent you from accidentally hosing yourself with
</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defstruct.html" target="_top"><code class="function">DEFSTRUCT</code></a> instance ...)
</pre><p>
and allow enforcing modularity.
Note that you will also get the <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#continuable">continuable</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> when you try to
assign (with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/spefor_setq.html" target="_top"><code class="function">SETQ</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_psetq.html" target="_top"><code class="function">PSETQ</code></a>, etc.) a value to an internal special
variable living in a locked package and not accessible in your current
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stpackagest.html" target="_top"><code class="varname">*PACKAGE*</code></a>, but only in the interpreted code and during compilation.
There is no check for package locks in compiled code because of the
performance considerations.
</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="clupack"></a>11.3. The
  <strong class="package"><span class="quote">“<span class="quote">COMMON-LISP-USER</span>”</span></strong> Package
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-2.html">[sec_11-1-2-2]</a></h2></div></div></div><p>The <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-2.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP-USER</span>”</span></strong></a> package uses the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong></a> and <a class="link" href="#ext-pac"><strong class="package"><span class="quote">“<span class="quote">EXT</span>”</span></strong></a> packages.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="imppack"></a>11.4. Implementation-Defined Packages
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-4.html">[sec_11-1-2-4]</a></h2></div></div></div><p>The following additional packages exist:</p><div class="variablelist"><p class="title"><strong>Implementation-Defined Packages</strong></p><dl class="variablelist"><dt><span class="term"><a class="link" href="#classes" title="4.2. Classes sec_4-3"><strong class="package"><span class="quote">“<span class="quote">CLOS</span>”</span></strong></a></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_export.html" target="_top"><code class="function">EXPORT</code></a>s all <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a>-specific symbols, including some
    <a class="link" href="#clos-diff" title="4.3. Deviations from ANSI CL standard">additional symbols</a>.
 </dd><dt><a id="sys-pac"></a><span class="term"><a class="link" href="#sys-pac"><strong class="package"><span class="quote">“<span class="quote">SYSTEM</span>”</span></strong></a></span></dt><dd>has the nickname <strong class="package"><span class="quote">“<span class="quote">SYS</span>”</span></strong>,
    and has no <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_export.html" target="_top"><code class="function">EXPORT</code></a>ed symbols.  It defines many system internals.
 </dd><dt><a id="ext-pac"></a><span class="term"><a class="link" href="#ext-pac"><strong class="package"><span class="quote">“<span class="quote">EXT</span>”</span></strong></a></span></dt><dd>
    is the umbrella package for all extensions: it imports and <a class="link" href="#re-export" title="11.1.3. Function EXT:RE-EXPORT"><code class="function">EXT:RE-EXPORT</code></a>s
    all the external symbols in all <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> extensions, so a simple
    <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_use-package.html" target="_top"><code class="function">USE-PACKAGE</code></a> "EXT")</code> is enough to
    make all the extensions available in the current package.
    This package uses packages (in addition to <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong></a>):
    <a class="link" href="#syscalls" title="33.2. System Calls"><strong class="package"><span class="quote">“<span class="quote">POSIX</span>”</span></strong></a>, <a class="link" href="#socket" title="32.4. Socket Streams"><strong class="package"><span class="quote">“<span class="quote">SOCKET</span>”</span></strong></a>, <a class="link" href="#gstream" title="31.6. Generic streams"><strong class="package"><span class="quote">“<span class="quote">GSTREAM</span>”</span></strong></a>, <a class="link" href="#gray" title="Chapter 30. Gray streams"><strong class="package"><span class="quote">“<span class="quote">GRAY</span>”</span></strong></a>,
    <a class="link" href="#i18n" title="31.4. Internationalization of CLISP"><strong class="package"><span class="quote">“<span class="quote">I18N</span>”</span></strong></a>, <a class="link" href="#customize" title="31.12. Customizing CLISP behavior"><strong class="package"><span class="quote">“<span class="quote">CUSTOM</span>”</span></strong></a>.</dd><dt><span class="term"><a class="link" href="#encoding" title="31.5. Encodings"><strong class="package"><span class="quote">“<span class="quote">CHARSET</span>”</span></strong></a></span></dt><dd>defines and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_export.html" target="_top"><code class="function">EXPORT</code></a>s some character sets, for use with
    <a class="link" href="#make-encoding" title="31.5.4. Function EXT:MAKE-ENCODING"><code class="function">EXT:MAKE-ENCODING</code></a> and as <a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a> argument.
 </dd><dt><span class="term"><a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a></span></dt><dd>implements the <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility">foreign function
     interface</a>.  Some platforms only.
 </dd><dt><span class="term"><a class="link" href="#screen" title="32.1. Random Screen Access"><strong class="package"><span class="quote">“<span class="quote">SCREEN</span>”</span></strong></a></span></dt><dd>defines an API for <a class="link" href="#screen" title="32.1. Random Screen Access">random screen
     access</a>.  Some platforms only.
 </dd><dt><span class="term"><a href="impnotes.html#package-case" class="olink"><strong class="package"><span class="quote">“<span class="quote">CS-COMMON-LISP</span>”</span></strong></a><br /></span><span class="term"><a href="impnotes.html#cs-clu" class="olink"><strong class="package"><span class="quote">“<span class="quote">CS-COMMON-LISP-USER</span>”</span></strong></a></span></dt><dd><a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-SENSITIVE</code></a> versions of <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong></a> and <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-2.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP-USER</span>”</span></strong></a>.
    See <a class="xref" href="#package-case" title="11.5. Package Case-Sensitivity">Section 11.5, “Package Case-Sensitivity”</a>.</dd></dl></div><p>All pre-existing packages except <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-2.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP-USER</span>”</span></strong></a> belong to the
 implementation, in the sense that the programs that do not follow
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1-2.html">[sec_11-1-2-1-2]</a>
 (<span class="quote">“<span class="quote">Constraints on the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">‘<span class="quote">COMMON-LISP</span>’</span></strong></a> Package for Conforming Programs</span>”</span>)
 cause undefined behavior.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="package-case"></a>11.5. Package Case-Sensitivity</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#cs-clu">11.5.1. User Package for the Case-sensitive World</a></span></dt><dt><span class="section"><a href="#cs-pack-name">11.5.2. Package Names</a></span></dt><dt><span class="section"><a href="#cs-gensym-kwd">11.5.3. Gensyms and Keywords</a></span></dt><dt><span class="section"><a href="#case-sensitive-migration">11.5.4. Migration Tips</a></span></dt><dt><span class="section"><a href="#case-sensitive-startup">11.5.5. Using case-sensitive packages by default</a></span></dt></dl></div><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> supports programs written with case sensitive symbols. For
example, with case sensitive symbols, the symbols <code class="literal">cdr</code>
(the function equivalent to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_rest.html" target="_top"><code class="function">REST</code></a>) and the symbol <code class="literal">CDR</code>
(a user-defined type denoting a Call Data Record) are different and unrelated.
</p><p>There are some incompatibilities between programs assuming case
sensitive symbols and programs assuming the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] case insensitive symbols.
For example, <code class="code">(eq 'KB 'Kb)</code> evaluates to false in a case
sensitive world and to true in a case insensitive world. However, unlike some
commercial <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> implementations, <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> allows both kinds of programs to
coexist in the same process and interoperate with each other. Example:
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="filename">OLD.lisp</code></span></dt><dd><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_in-package.html" target="_top"><code class="function">IN-PACKAGE</code></a> "OLD")
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defun.html" target="_top"><code class="function">DEFUN</code></a> FOO () ...)
</pre></dd><dt><span class="term"><code class="filename">modern.lisp</code></span></dt><dd><pre class="programlisting">
(in-package "NEW")
(defun bar () (old:foo))
(symbol-name 'bar) ; ⇒ <code class="computeroutput">"bar"</code>
</pre></dd></dl></div><p>This is achieved through specification of the symbol case policy at
the package level. A <strong class="first"><em class="firstterm">modern package
  <a id="pack-modern" class="indexterm"></a></em></strong>
 is one that is declared to be both case-sensitive and case-inverted and
 which use the symbols from the <a href="impnotes.html#package-case" class="olink"><strong class="package"><span class="quote">“<span class="quote">CS-COMMON-LISP</span>”</span></strong></a> package.</p><p>A <strong class="first"><em class="firstterm">case-sensitive package
  <a id="pack-case-sensitive" class="indexterm"></a></em></strong>
 is one whose <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defpackage.html" target="_top"><code class="function">DEFPACKAGE</code></a> declaration (or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-package.html" target="_top"><code class="function">MAKE-PACKAGE</code></a>
 creation form) has the option <code class="code">(<a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-SENSITIVE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>)</code>.
 In a case-sensitive package, the reader does <span class="strong"><strong>not</strong></span> uppercase the
 symbol name before calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_intern.html" target="_top"><code class="function">INTERN</code></a>.  Similarly, the printer, when
 printing the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_symbol-name.html" target="_top"><code class="function">SYMBOL-NAME</code></a> part of a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a> (i.e. the part after
 the package markers), behaves as if the readtable's case were set
 to <code class="constant">:PRESERVE</code>.
 See also <a class="xref" href="#pack-sensitive" title="11.1.5. Function EXT:PACKAGE-CASE-SENSITIVE-P">Section 11.1.5, “Function <code class="function">EXT:PACKAGE-CASE-SENSITIVE-P</code>”</a>.</p><p>A <strong class="first"><em class="firstterm">case-inverted package
  <a id="pack-case-inverted" class="indexterm"></a>
 </em></strong> is one whose <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defpackage.html" target="_top"><code class="function">DEFPACKAGE</code></a> declaration (or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-package.html" target="_top"><code class="function">MAKE-PACKAGE</code></a>
 creation form) has the option <code class="code">(<a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-INVERTED</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>)</code>.
 In the context of a case-inverted package, symbol names are
 case-inverted: upper case characters are mapped to lower case, lower
 case characters are mapped to upper case, and other characters are left
 untouched.  Every symbol thus conceptually has two symbol names: an
 old-world symbol name and a modern-world symbol name, which is the
 case-inverted old-world name.  The first symbol name is returned by the
 function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_symbol-name.html" target="_top"><code class="function">SYMBOL-NAME</code></a>, the modern one by the
 function <code class="function">cs-cl:symbol-name</code>.  The internal
 functions for creating or looking up symbols in a package, which
 traditionally took a string argument, now conceptually take two string
 arguments: old-style-string and inverted-string.  Actually, a function
 like <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_intern.html" target="_top"><code class="function">INTERN</code></a> takes the old-style-string as argument and computes the
 inverted-string from it; whereas the
 function <code class="function">cs-cl:intern</code> takes the inverted-string as
 argument and computes the old-style-string from it.
 See also <a class="xref" href="#pack-inverted" title="11.1.4. Function EXT:PACKAGE-CASE-INVERTED-P">Section 11.1.4, “Function <code class="function">EXT:PACKAGE-CASE-INVERTED-P</code>”</a>.</p><p>For a few built-in functions, a variant for the case-inverted
world is defined in the <a href="impnotes.html#package-case" class="olink"><strong class="package"><span class="quote">“<span class="quote">CS-COMMON-LISP</span>”</span></strong></a> package, which has the nickname
 <strong class="package"><span class="quote">“<span class="quote">CS-CL</span>”</span></strong>:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="function">cs-cl:symbol-name</code></span></dt><dd>returns the case-inverted symbol name.
  </dd><dt><span class="term"><code class="function">cs-cl:intern</code><br /></span><span class="term"><code class="function">cs-cl:find-symbol</code></span></dt><dd>work consistently with
     <code class="function">cs-cl:symbol-name</code>.</dd><dt><span class="term"><code class="function">cs-cl:shadow</code><br /></span><span class="term"><code class="function">cs-cl:find-all-symbols</code><br /></span><span class="term"><code class="function">cs-cl:string=</code><br /></span><span class="term"><code class="function">cs-cl:string/=</code><br /></span><span class="term"><code class="function">cs-cl:string&lt;</code><br /></span><span class="term"><code class="function">cs-cl:string&gt;</code><br /></span><span class="term"><code class="function">cs-cl:string&lt;=</code><br /></span><span class="term"><code class="function">cs-cl:string&gt;=</code><br /></span><span class="term"><code class="function">cs-cl:string-trim</code><br /></span><span class="term"><code class="function">cs-cl:string-left-trim</code><br /></span><span class="term"><code class="function">cs-cl:string-right-trim</code></span></dt><dd>convert a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a> to a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> and therefore
     exist in a variant that uses <code class="function">cs-cl:symbol-name</code>
     instead of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_symbol-name.html" target="_top"><code class="function">SYMBOL-NAME</code></a>.</dd><dt><span class="term"><code class="function">cs-cl:make-package</code></span></dt><dd>creates a case-inverted <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_package.html" target="_top"><code class="classname">PACKAGE</code></a>.
</dd></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="cs-clu"></a>11.5.1. User Package for the Case-sensitive World</h3></div></div></div><p>A package <a href="impnotes.html#cs-clu" class="olink"><strong class="package"><span class="quote">“<span class="quote">CS-COMMON-LISP-USER</span>”</span></strong></a> is provided for the user to modify and work in.
It plays the same role as <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-2.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP-USER</span>”</span></strong></a>, but for the case-sensitive
world.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="cs-pack-name"></a>11.5.2. Package Names</h3></div></div></div><p>The handling of package names is unchanged.  Package names are
 still usually uppercase.  The package names are also subject to
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_readtable-case.html" target="_top"><code class="function">READTABLE-CASE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_streadtablest.html" target="_top"><code class="varname">*READTABLE*</code></a>)</code>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="cs-gensym-kwd"></a>11.5.3. Gensyms and Keywords</h3></div></div></div><p>Note that gensyms and keywords are still treated traditionally:
even in a case-sensitive package,</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stringeqc_ng-not-lessp.html" target="_top"><code class="function">STRING=</code></a> '#:FooBar '#:foobar)
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a></code>
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a> ':KeyWord ':keyword)
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a></code></pre><p>
We believe this has a limited negative impact for the moment,
but can be changed some time in the future.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="case-sensitive-migration"></a>11.5.4. Migration Tips</h3></div></div></div><p>The following practices will pose no problems when migrating to a
modern case-sensitive world:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Using [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] symbols in lowercase.</li><li class="listitem">Macros that create symbols by suffixing or prefixing
  given symbols.</li><li class="listitem">Comparing symbol names as in
  <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stringeqc_ng-not-lessp.html" target="_top"><code class="function">STRING=</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_symbol-name.html" target="_top"><code class="function">SYMBOL-NAME</code></a> <em class="replaceable"><code>x</code></em>) (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_symbol-name.html" target="_top"><code class="function">SYMBOL-NAME</code></a> <em class="replaceable"><code>y</code></em>))</code>.
</li></ul></div><p>The following practices will not work in a case-sensitive world or
can give problems:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Accessing the same symbol in both upper- and
  lowercase from the same source file.</li><li class="listitem">Macros that create symbols in other packages than the
  original symbols.</li><li class="listitem">Comparing <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_symbol-name.html" target="_top"><code class="function">SYMBOL-NAME</code></a> return values with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a>.
</li><li class="listitem">Comparing <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_symbol-name.html" target="_top"><code class="function">SYMBOL-NAME</code></a> x)</code> with
  <code class="code">(cs-cl:symbol-name y)</code>.</li></ul></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="case-sensitive-startup"></a>11.5.5. Using case-sensitive packages by default</h3></div></div></div><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> supports a command-line option <code class="option"><a href="clisp.html#opt-modern" class="olink">-modern</a></code> that
 sets the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stpackagest.html" target="_top"><code class="varname">*PACKAGE*</code></a> initially to the <a href="impnotes.html#cs-clu" class="olink"><strong class="package"><span class="quote">“<span class="quote">CS-COMMON-LISP-USER</span>”</span></strong></a> package, and
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-casest.html" target="_top"><code class="varname">*PRINT-CASE*</code></a> to <code class="constant">:DOWNCASE</code>.</p><p>For packages to be located in the <span class="quote">“<span class="quote">modern</span>”</span>
 (case-sensitive) world, you need to augment their <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defpackage.html" target="_top"><code class="function">DEFPACKAGE</code></a>
 declaration by adding the option <code class="code">(<a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:MODERN</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>)</code>,
 see <a class="xref" href="#defpack" title="11.1.2. Macro DEFPACKAGE">Section 11.1.2, “Macro <code class="function">DEFPACKAGE</code>”</a>.</p></div></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="numbers"></a>Chapter 12. Numbers <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-12.html">[chap-12]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#num-types">12.1. Numeric Types</a></span></dt><dt><span class="section"><a href="#num-concepts">12.2. Number Concepts   sec_12-1</a></span></dt><dd><dl><dt><span class="section"><a href="#num-ops">12.2.1. Numeric Operations   sec_12-1-1</a></span></dt><dd><dl><dt><span class="section"><a href="#int-func-ext">12.2.1.1. Additional Integer Functions</a></span></dt><dt><span class="section"><a href="#float-decode">12.2.1.2. Function <code class="function">DECODE-FLOAT</code></a></span></dt><dt><span class="section"><a href="#bool-ops">12.2.1.3. Boolean Operations   convar_boole-_cm_boole-xor</a></span></dt><dt><span class="section"><a href="#byte-type">12.2.1.4. Byte Operations on Integers   sec_12-1-1-3-2</a></span></dt><dt><span class="section"><a href="#float-notes">12.2.1.5. Floating Point Arithmetics</a></span></dt></dl></dd><dt><span class="section"><a href="#num-const">12.2.2. Implementation-Dependent Numeric Constants   sec_12-1-2</a></span></dt><dd><dl><dt><span class="section"><a href="#fixnum-lim">12.2.2.1. Fixnum Limits</a></span></dt><dt><span class="section"><a href="#bignum-lim">12.2.2.2. Bignum Limits</a></span></dt><dt><span class="section"><a href="#float-lim">12.2.2.3. Float Limits</a></span></dt></dl></dd><dt><span class="section"><a href="#float-subst">12.2.3. Rule of Float Substitutability   sec_12-1-3-3</a></span></dt><dt><span class="section"><a href="#float-comp">12.2.4. Floating-point Computations   sec_12-1-4</a></span></dt><dd><dl><dt><span class="section"><a href="#flocont">12.2.4.1. Rule of Float Precision Contagion   sec_12-1-4-4</a></span></dt><dt><span class="section"><a href="#floratcont">12.2.4.2. Rule of Float and Rational Contagion   sec_12-1-4-1</a></span></dt></dl></dd><dt><span class="section"><a href="#complex-comp">12.2.5. Complex Computations   sec_12-1-5</a></span></dt><dt><span class="section"><a href="#complex-rational">12.2.6. Rule of Canonical Representation   for Complex Rationals sec_12-1-5-3</a></span></dt><dt><span class="section"><a href="#random-state">12.2.7. Random-State Operations   sec_12-1-7</a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="num-types"></a>12.1. Numeric Types</h2></div></div></div><p>The type <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_number.html" target="_top"><code class="classname">NUMBER</code></a> is the disjoint union of the types
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_real.html" target="_top"><code class="classname">REAL</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_complex.html" target="_top"><code class="classname">COMPLEX</code></a> (<a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#exhaustive_partition">exhaustive
 partition</a>)</p><p>The type <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_real.html" target="_top"><code class="classname">REAL</code></a> is the disjoint union of the types
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_rational.html" target="_top"><code class="classname">RATIONAL</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_float.html" target="_top"><code class="classname">FLOAT</code></a>.</p><p>The type <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_rational.html" target="_top"><code class="classname">RATIONAL</code></a> is the disjoint union of the types
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_ratio.html" target="_top"><code class="classname">RATIO</code></a>.</p><p>The type <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> is the disjoint union of the types
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_fixnum.html" target="_top"><code class="classname">FIXNUM</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_bignum.html" target="_top"><code class="classname">BIGNUM</code></a>.</p><p>The type <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_float.html" target="_top"><code class="classname">FLOAT</code></a> is the disjoint union of the types
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SHORT-FLOAT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SINGLE-FLOAT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">DOUBLE-FLOAT</code></a> and
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">LONG-FLOAT</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="num-concepts"></a>12.2. Number Concepts
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_12-1.html">[sec_12-1]</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#num-ops">12.2.1. Numeric Operations   sec_12-1-1</a></span></dt><dd><dl><dt><span class="section"><a href="#int-func-ext">12.2.1.1. Additional Integer Functions</a></span></dt><dt><span class="section"><a href="#float-decode">12.2.1.2. Function <code class="function">DECODE-FLOAT</code></a></span></dt><dt><span class="section"><a href="#bool-ops">12.2.1.3. Boolean Operations   convar_boole-_cm_boole-xor</a></span></dt><dt><span class="section"><a href="#byte-type">12.2.1.4. Byte Operations on Integers   sec_12-1-1-3-2</a></span></dt><dt><span class="section"><a href="#float-notes">12.2.1.5. Floating Point Arithmetics</a></span></dt></dl></dd><dt><span class="section"><a href="#num-const">12.2.2. Implementation-Dependent Numeric Constants   sec_12-1-2</a></span></dt><dd><dl><dt><span class="section"><a href="#fixnum-lim">12.2.2.1. Fixnum Limits</a></span></dt><dt><span class="section"><a href="#bignum-lim">12.2.2.2. Bignum Limits</a></span></dt><dt><span class="section"><a href="#float-lim">12.2.2.3. Float Limits</a></span></dt></dl></dd><dt><span class="section"><a href="#float-subst">12.2.3. Rule of Float Substitutability   sec_12-1-3-3</a></span></dt><dt><span class="section"><a href="#float-comp">12.2.4. Floating-point Computations   sec_12-1-4</a></span></dt><dd><dl><dt><span class="section"><a href="#flocont">12.2.4.1. Rule of Float Precision Contagion   sec_12-1-4-4</a></span></dt><dt><span class="section"><a href="#floratcont">12.2.4.2. Rule of Float and Rational Contagion   sec_12-1-4-1</a></span></dt></dl></dd><dt><span class="section"><a href="#complex-comp">12.2.5. Complex Computations   sec_12-1-5</a></span></dt><dt><span class="section"><a href="#complex-rational">12.2.6. Rule of Canonical Representation   for Complex Rationals sec_12-1-5-3</a></span></dt><dt><span class="section"><a href="#random-state">12.2.7. Random-State Operations   sec_12-1-7</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="num-ops"></a>12.2.1. Numeric Operations
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_12-1-1.html">[sec_12-1-1]</a></h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#int-func-ext">12.2.1.1. Additional Integer Functions</a></span></dt><dt><span class="section"><a href="#float-decode">12.2.1.2. Function <code class="function">DECODE-FLOAT</code></a></span></dt><dt><span class="section"><a href="#bool-ops">12.2.1.3. Boolean Operations   convar_boole-_cm_boole-xor</a></span></dt><dt><span class="section"><a href="#byte-type">12.2.1.4. Byte Operations on Integers   sec_12-1-1-3-2</a></span></dt><dt><span class="section"><a href="#float-notes">12.2.1.5. Floating Point Arithmetics</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="int-func-ext"></a>12.2.1.1. Additional Integer Functions</h4></div></div></div><p><a id="factorial"></a><strong>Function <code class="function">EXT:!</code> </strong><code class="code">(<code class="function">EXT:!</code> <em class="replaceable"><code>n</code></em>)</code> returns the
 factorial of <em class="replaceable"><code>n</code></em>, <em class="replaceable"><code>n</code></em> being a nonnegative <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>.</p><p><a id="exquo"></a><strong>Function <code class="function">EXT:EXQUO</code>. </strong><code class="code">(<code class="function">EXT:EXQUO</code> <em class="replaceable"><code>x</code></em> <em class="replaceable"><code>y</code></em>)</code> returns
 the integer quotient <code class="varname">x/y</code> of two integers
 <em class="replaceable"><code>x</code></em>,<em class="replaceable"><code>y</code></em>, and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> when the quotient is not
 integer.  (This is more efficient than <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_sl.html" target="_top"><code class="function">/</code></a>.)</p><p><a id="xgcd"></a><strong>Function <code class="function">EXT:XGCD</code>. </strong><code class="code">(<code class="function">EXT:XGCD</code> <em class="replaceable"><code>x<sub>1</sub></code></em> ... <em class="replaceable"><code>x<sub>n</sub></code></em>)</code>
 returns the values <em class="replaceable"><code>l</code></em>, <em class="replaceable"><code>k<sub>1</sub></code></em>, ..., <em class="replaceable"><code>k<sub>n</sub></code></em>, where <em class="replaceable"><code>l</code></em> is the
 greatest common divisor of the integers <em class="replaceable"><code>x<sub>1</sub></code></em>, ..., <em class="replaceable"><code>x<sub>n</sub></code></em>, and
 <em class="replaceable"><code>k<sub>1</sub></code></em>, ..., <em class="replaceable"><code>k<sub>n</sub></code></em> are the integer coefficients such that
</p><pre class="programlisting">
<em class="replaceable"><code>l</code></em> = (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_gcd.html" target="_top"><code class="function">GCD</code></a> <em class="replaceable"><code>x<sub>1</sub></code></em> ... <em class="replaceable"><code>x<sub>n</sub></code></em>)
  = (+ (* <em class="replaceable"><code>k<sub>1</sub></code></em> <em class="replaceable"><code>x<sub>1</sub></code></em>) ... (* <em class="replaceable"><code>k<sub>n</sub></code></em> <em class="replaceable"><code>x<sub>n</sub></code></em>))
</pre><p><a id="mod-expt"></a><strong>Function <a class="link" href="#mod-expt" title="Function EXT:MOD-EXPT"><code class="function">EXT:MOD-EXPT</code></a>. </strong><code class="code">(<a class="link" href="#mod-expt" title="Function EXT:MOD-EXPT"><code class="function">EXT:MOD-EXPT</code></a> <em class="replaceable"><code>k</code></em> <em class="replaceable"><code>l</code></em> <em class="replaceable"><code>m</code></em>)</code>
 is equivalent to <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_modcm_rem.html" target="_top"><code class="function">MOD</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_expcm_expt.html" target="_top"><code class="function">EXPT</code></a> <em class="replaceable"><code>k</code></em> <em class="replaceable"><code>l</code></em>) <em class="replaceable"><code>m</code></em>)</code>
 except it is more efficient for very large arguments.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="float-decode"></a>12.2.1.2. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_decode-fl_decode-float.html" target="_top"><code class="function">DECODE-FLOAT</code></a></h4></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_decode-fl_decode-float.html" target="_top"><code class="function">FLOAT-RADIX</code></a> always returns <span class="returnvalue">2</span>.</p><p><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_decode-fl_decode-float.html" target="_top"><code class="function">FLOAT-DIGITS</code></a> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>digits</code></em>)</code> coerces
 <em class="replaceable"><code>number</code></em> (a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_real.html" target="_top"><code class="classname">REAL</code></a>) to a floating point number with at least
 <em class="replaceable"><code>digits</code></em> mantissa digits.  The following always evaluates to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>:
 </p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eqcm_sleq__lteqcm_gteq.html" target="_top"><code class="function">&gt;=</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_decode-fl_decode-float.html" target="_top"><code class="function">FLOAT-DIGITS</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_decode-fl_decode-float.html" target="_top"><code class="function">FLOAT-DIGITS</code></a> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>digits</code></em>)) <em class="replaceable"><code>digits</code></em>)
</pre></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="bool-ops"></a>12.2.1.3. Boolean Operations
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_boole-_cm_boole-xor.html">[convar_boole-_cm_boole-xor]</a></h4></div></div></div><div class="table"><a id="bool-op-table"></a><p class="title"><strong>Table 12.1. Boolean operations</strong></p><div class="table-contents"><table class="table" summary="Boolean operations" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="left">constant</th><th align="left">value</th></tr></thead><tbody><tr><td align="left"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_boole-_cm_boole-xor.html" target="_top"><code class="constant">BOOLE-CLR</code></a></td><td align="left">0</td></tr><tr><td align="left"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_boole-_cm_boole-xor.html" target="_top"><code class="constant">BOOLE-SET</code></a></td><td align="left">15</td></tr><tr><td align="left"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_boole-_cm_boole-xor.html" target="_top"><code class="constant">BOOLE-1</code></a></td><td align="left">10</td></tr><tr><td align="left"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_boole-_cm_boole-xor.html" target="_top"><code class="constant">BOOLE-2</code></a></td><td align="left">12</td></tr><tr><td align="left"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_boole-_cm_boole-xor.html" target="_top"><code class="constant">BOOLE-C1</code></a></td><td align="left">5</td></tr><tr><td align="left"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_boole-_cm_boole-xor.html" target="_top"><code class="constant">BOOLE-C2</code></a></td><td align="left">3</td></tr><tr><td align="left"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_boole-_cm_boole-xor.html" target="_top"><code class="constant">BOOLE-AND</code></a></td><td align="left">8</td></tr><tr><td align="left"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_boole-_cm_boole-xor.html" target="_top"><code class="constant">BOOLE-IOR</code></a></td><td align="left">14</td></tr><tr><td align="left"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_boole-_cm_boole-xor.html" target="_top"><code class="constant">BOOLE-XOR</code></a></td><td align="left">6</td></tr><tr><td align="left"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_boole-_cm_boole-xor.html" target="_top"><code class="constant">BOOLE-EQV</code></a></td><td align="left">9</td></tr><tr><td align="left"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_boole-_cm_boole-xor.html" target="_top"><code class="constant">BOOLE-NAND</code></a></td><td align="left">7</td></tr><tr><td align="left"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_boole-_cm_boole-xor.html" target="_top"><code class="constant">BOOLE-NOR</code></a></td><td align="left">1</td></tr><tr><td align="left"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_boole-_cm_boole-xor.html" target="_top"><code class="constant">BOOLE-ANDC1</code></a></td><td align="left">4</td></tr><tr><td align="left"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_boole-_cm_boole-xor.html" target="_top"><code class="constant">BOOLE-ANDC2</code></a></td><td align="left">2</td></tr><tr><td align="left"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_boole-_cm_boole-xor.html" target="_top"><code class="constant">BOOLE-ORC1</code></a></td><td align="left">13</td></tr><tr><td align="left"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_boole-_cm_boole-xor.html" target="_top"><code class="constant">BOOLE-ORC2</code></a></td><td align="left">11</td></tr></tbody></table></div></div><br class="table-break" /></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="byte-type"></a>12.2.1.4. Byte Operations on Integers
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_12-1-1-3-2.html">[sec_12-1-1-3-2]</a></h4></div></div></div><p>Byte specifiers are objects of built-in type <a class="link" href="#byte-type" title="12.2.1.4. Byte Operations on Integers sec_12-1-1-3-2"><span class="type">BYTE</span></a>,
 not <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>s.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="float-notes"></a>12.2.1.5. Floating Point Arithmetics</h4></div></div></div><p><a id="expt"></a><strong>Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_expcm_expt.html" target="_top"><code class="function">EXPT</code></a>. </strong><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_expcm_expt.html" target="_top"><code class="function">EXPT</code></a> <em class="replaceable"><code>base</code></em> <em class="replaceable"><code>exponent</code></em>)</code>
 is not very precise if <em class="replaceable"><code>exponent</code></em> has a large
 absolute value.</p><p><a id="log"></a><strong>Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_log.html" target="_top"><code class="function">LOG</code></a>. </strong><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_log.html" target="_top"><code class="function">LOG</code></a> <em class="replaceable"><code>number</code></em> <em class="replaceable"><code>base</code></em>)</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> if
 <code class="literal"><em class="replaceable"><code>base</code></em> = 1</code>.</p><p><a id="pi"></a><strong>Constant <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_pi.html" target="_top"><code class="constant">PI</code></a>. </strong>The value of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_pi.html" target="_top"><code class="constant">PI</code></a> is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">LONG-FLOAT</code></a> with the precision given
  by <code class="code">(<a class="link" href="#lfd" title="Arbitrary Precision Floats"><code class="function">EXT:LONG-FLOAT-DIGITS</code></a>)</code>.  When this precision is changed, the value of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_pi.html" target="_top"><code class="constant">PI</code></a> is
  automatically recomputed.  Therefore <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_pi.html" target="_top"><code class="constant">PI</code></a> is <span class="strong"><strong>not</strong></span> a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-1-3.html">constant variable</a>.
</p><p><a id="ucpt"></a><strong>Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_upgraded-_ex-part-type.html" target="_top"><code class="function">UPGRADED-COMPLEX-PART-TYPE</code></a>. </strong>When the argument is not a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_r.html#recognizable_subtype">recognizable subtype</a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_real.html" target="_top"><code class="classname">REAL</code></a>,
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_upgraded-_ex-part-type.html" target="_top"><code class="function">UPGRADED-COMPLEX-PART-TYPE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>, otherwise it
 returns its argument (even though a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_complex.html" target="_top"><code class="classname">COMPLEX</code></a> number in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> can
 always have <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_realpartcm_imagpart.html" target="_top"><code class="function">REALPART</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_realpartcm_imagpart.html" target="_top"><code class="function">IMAGPART</code></a> of any type) because it allows
 the most precise type inference.</p><p><a id="default-float-format"></a><strong>Variable <a class="link" href="#default-float-format" title="Variable CUSTOM:*DEFAULT-FLOAT-FORMAT*"><code class="varname">CUSTOM:*DEFAULT-FLOAT-FORMAT*</code></a>. </strong>When rational numbers are to be converted to floats (due to
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_float.html" target="_top"><code class="function">FLOAT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_coerce.html" target="_top"><code class="function">COERCE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_sqrtcm_isqrt.html" target="_top"><code class="function">SQRT</code></a> or a transcendental function), the result
 type is given by the variable <a class="link" href="#default-float-format" title="Variable CUSTOM:*DEFAULT-FLOAT-FORMAT*"><code class="varname">CUSTOM:*DEFAULT-FLOAT-FORMAT*</code></a>.
 See also <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stread-de_oat-formatst.html" target="_top"><code class="varname">*READ-DEFAULT-FLOAT-FORMAT*</code></a>.</p><p><a id="no-underflow"></a><strong>Macro <a class="link" href="#no-underflow" title="Macro EXT:WITHOUT-FLOATING-POINT-UNDERFLOW"><code class="function">EXT:WITHOUT-FLOATING-POINT-UNDERFLOW</code></a>. </strong>The macro <code class="code">(<a class="link" href="#no-underflow" title="Macro EXT:WITHOUT-FLOATING-POINT-UNDERFLOW"><code class="function">EXT:WITHOUT-FLOATING-POINT-UNDERFLOW</code></a> {<em class="replaceable"><code>form</code></em>}*)</code> executes the
 <em class="replaceable"><code>form</code></em>s, with errors of type <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_floati_nt-underflow.html" target="_top"><code class="classname">FLOATING-POINT-UNDERFLOW</code></a> inhibited.
 Floating point operations will silently return zero instead of
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ing an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> of type <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_floati_nt-underflow.html" target="_top"><code class="classname">FLOATING-POINT-UNDERFLOW</code></a>.
</p><p><a id="float-invalid-op"></a><strong>Condition <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_floati_id-operation.html" target="_top"><code class="classname">FLOATING-POINT-INVALID-OPERATION</code></a>. </strong>This <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_condition.html" target="_top"><code class="classname">CONDITION</code></a> is never <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed by <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.</p><p><a id="float-inexact"></a><strong>Condition <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_floati_oint-inexact.html" target="_top"><code class="classname">FLOATING-POINT-INEXACT</code></a>. </strong>This <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_condition.html" target="_top"><code class="classname">CONDITION</code></a> is never <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed by <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="num-const"></a>12.2.2. Implementation-Dependent Numeric Constants
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_12-1-2.html">[sec_12-1-2]</a></h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#fixnum-lim">12.2.2.1. Fixnum Limits</a></span></dt><dt><span class="section"><a href="#bignum-lim">12.2.2.2. Bignum Limits</a></span></dt><dt><span class="section"><a href="#float-lim">12.2.2.3. Float Limits</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="fixnum-lim"></a>12.2.2.1. Fixnum Limits</h4></div></div></div><div class="table"><a id="fixnum-lim-table"></a><p class="title"><strong>Table 12.2. Fixnum limits</strong></p><div class="table-contents"><table class="table" summary="Fixnum limits" border="1"><colgroup><col align="center" class="vars" /><col align="center" class="b32" /><col align="center" class="b64" /></colgroup><thead><tr><th align="center">CPU type</th><th align="center">32-bit CPU</th><th align="center">64-bit CPU</th></tr></thead><tbody><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_ative-fixnum.html" target="_top"><code class="constant">MOST-POSITIVE-FIXNUM</code></a></td><td align="center">2<sup>24</sup>-1 = 16777215</td><td align="center">2<sup>48</sup>-1 = 281474976710655</td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_ative-fixnum.html" target="_top"><code class="constant">MOST-NEGATIVE-FIXNUM</code></a></td><td align="center">-2<sup>24</sup> = -16777216</td><td align="center">-2<sup>48</sup> = -281474976710656</td></tr></tbody></table></div></div><br class="table-break" /></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="bignum-lim"></a>12.2.2.2. Bignum Limits</h4></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_bignum.html" target="_top"><code class="classname">BIGNUM</code></a>s are limited in size.  Their maximum size is
 <code class="literal">32*(2<sup>16</sup>-2)=2097088</code> bits.
 The largest representable <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_bignum.html" target="_top"><code class="classname">BIGNUM</code></a> is therefore
 <code class="literal">2<sup>2097088</sup>-1</code>.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="float-lim"></a>12.2.2.3. Float Limits</h4></div></div></div><p>Together with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_pi.html" target="_top"><code class="constant">PI</code></a>, the other <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">LONG-FLOAT</code></a> constants
 </p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_d-long-float.html" target="_top"><code class="constant">LEAST-NEGATIVE-LONG-FLOAT</code></a></td><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_short-_tive-epsilon.html" target="_top"><code class="constant">LONG-FLOAT-EPSILON</code></a></td></tr><tr><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_d-long-float.html" target="_top"><code class="constant">LEAST-NEGATIVE-NORMALIZED-LONG-FLOAT</code></a></td><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_short-_tive-epsilon.html" target="_top"><code class="constant">LONG-FLOAT-NEGATIVE-EPSILON</code></a></td></tr><tr><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_d-long-float.html" target="_top"><code class="constant">LEAST-POSITIVE-LONG-FLOAT</code></a></td><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_d-long-float.html" target="_top"><code class="constant">MOST-NEGATIVE-LONG-FLOAT</code></a></td></tr><tr><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_d-long-float.html" target="_top"><code class="constant">LEAST-POSITIVE-NORMALIZED-LONG-FLOAT</code></a></td><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_d-long-float.html" target="_top"><code class="constant">MOST-POSITIVE-LONG-FLOAT</code></a></td></tr></table><p>
 are recomputed whenever <code class="code">(<a class="link" href="#lfd" title="Arbitrary Precision Floats"><code class="function">EXT:LONG-FLOAT-DIGITS</code></a>)</code> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>ed.
 They are <span class="strong"><strong>not</strong></span> <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-1-3.html">constant variable</a>s.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="long-float-wider-than-bignum"></a>Warning</h3><p>Since the exponent of a
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">LONG-FLOAT</code></a> is a <a class="link" href="#floating-types-table">signed 32-bits
   integer</a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_d-long-float.html" target="_top"><code class="constant">MOST-POSITIVE-LONG-FLOAT</code></a> is about
  <code class="literal">2<sup>2<sup>31</sup></sup></code>,
  which is <span class="emphasis"><em>much</em></span> larger that the largest
  representable <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_bignum.html" target="_top"><code class="classname">BIGNUM</code></a>, which is <a class="link" href="#bignum-lim" title="12.2.2.2. Bignum Limits">less than</a>
  <code class="literal">2<sup>2<sup>21</sup></sup></code>.
  This, obviously, means that <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_floorcm_f_undcm_fround.html" target="_top"><code class="function">ROUND</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_floorcm_f_undcm_fround.html" target="_top"><code class="function">TRUNCATE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_floorcm_f_undcm_fround.html" target="_top"><code class="function">FLOOR</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_floorcm_f_undcm_fround.html" target="_top"><code class="function">CEILING</code></a>
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> on large <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">LONG-FLOAT</code></a>s.
  Less obviously, this means that <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> "<a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-3-2.html"><code class="literal">~E</code></a>"
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_d-long-float.html" target="_top"><code class="constant">MOST-POSITIVE-LONG-FLOAT</code></a>)</code> also fails.</p></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="float-subst"></a>12.2.3. Rule of Float Substitutability
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_12-1-3-3.html">[sec_12-1-3-3]</a></h3></div></div></div><p>When a mathematical function may return an exact (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_rational.html" target="_top"><code class="classname">RATIONAL</code></a>) or
 inexact (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_float.html" target="_top"><code class="classname">FLOAT</code></a>) result, it always returns the exact result.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="float-comp"></a>12.2.4. Floating-point Computations
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_12-1-4.html">[sec_12-1-4]</a></h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#flocont">12.2.4.1. Rule of Float Precision Contagion   sec_12-1-4-4</a></span></dt><dt><span class="section"><a href="#floratcont">12.2.4.2. Rule of Float and Rational Contagion   sec_12-1-4-1</a></span></dt></dl></div><p>There are four floating point types: <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SHORT-FLOAT</code></a>,
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SINGLE-FLOAT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">DOUBLE-FLOAT</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">LONG-FLOAT</code></a>:
</p><div class="informaltable"><a id="floating-types-table"></a><table class="informaltable" border="1"><colgroup><col /><col /><col /><col /><col /></colgroup><thead><tr><th align="center">type</th><th align="center">sign</th><th align="center">mantissa</th><th align="center">exponent</th><th align="center">comment</th></tr></thead><tbody><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SHORT-FLOAT</code></a></td><td align="center">1 bit</td><td align="center">16+1 bits</td><td align="center">8 bits</td><td align="center">immediate</td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SINGLE-FLOAT</code></a></td><td align="center">1 bit</td><td align="center">23+1 bits</td><td align="center">8 bits</td><td align="center"><a class="ulink" href="http://grouper.ieee.org/groups/754/" target="_top">IEEE 754</a></td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">DOUBLE-FLOAT</code></a></td><td align="center">1 bit</td><td align="center">52+1 bits</td><td align="center">11 bits</td><td align="center"><a class="ulink" href="http://grouper.ieee.org/groups/754/" target="_top">IEEE 754</a></td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">LONG-FLOAT</code></a></td><td align="center">1 bit</td><td align="center">&gt;=64 bits</td><td align="center">32 bits</td><td align="center">variable
 length</td></tr></tbody></table></div><p>The single and double float formats are those of the <a class="ulink" href="http://grouper.ieee.org/groups/754/" target="_top">IEEE 754</a>
 <span class="quote">“<span class="quote">Standard for Binary Floating-Point Arithmetic</span>”</span>,
 except that <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> does not support features like
 <code class="literal">±0</code>, <code class="literal">±inf</code>,
 <code class="literal">NaN</code>, gradual underflow, etc.
 <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> does not make use of these features, so, to reduce portability
 problems, <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> by design returns the same floating point results on
 all platforms (<a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> has a floating-point emulation built in for
 platforms that do not support <a class="ulink" href="http://grouper.ieee.org/groups/754/" target="_top">IEEE 754</a>).  Note that
 </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">When you got a <code class="literal">NaN</code>
    in your program, your program is broken, so you will spend time
    determining where the <code class="literal">NaN</code> came from.
    It is better to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a> an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> in this case.</li><li class="listitem">When you got unnormalized floats in your program,
    your results will have a greatly reduced accuracy anyway.
    Since <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> has the means to cope with this - <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">LONG-FLOAT</code></a>s of
    <a class="link" href="#lfd" title="Arbitrary Precision Floats">variable precision</a> - it does not
    need unnormalized floats.</li></ul></div><p>
 This is why <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a> does not contain the
 <code class="constant">:IEEE-FLOATING-POINT</code> keyword.</p><p><a id="lfd"></a><strong>Arbitrary Precision Floats. </strong><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">LONG-FLOAT</code></a>s have variable mantissa length, which is a
 multiple of 16 (or 32, depending on the word size of the processor).
 The default length used when <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">LONG-FLOAT</code></a>s are <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_readcm_re_g-whitespace.html" target="_top"><code class="function">READ</code></a> is given by the
 <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a> <code class="code">(<a class="link" href="#lfd" title="Arbitrary Precision Floats"><code class="function">EXT:LONG-FLOAT-DIGITS</code></a>)</code>.  It can be set by <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="link" href="#lfd" title="Arbitrary Precision Floats"><code class="function">EXT:LONG-FLOAT-DIGITS</code></a>) <em class="replaceable"><code>n</code></em>)</code>,
 where <em class="replaceable"><code>n</code></em> is a positive <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>.  E.g., <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="link" href="#lfd" title="Arbitrary Precision Floats"><code class="function">EXT:LONG-FLOAT-DIGITS</code></a>)
 3322)</code> sets the default precision of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">LONG-FLOAT</code></a>s to about
 1000 decimal digits.</p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="flocont"></a>12.2.4.1. Rule of Float Precision Contagion
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_12-1-4-4.html">[sec_12-1-4-4]</a></h4></div></div></div><p>The floating point contagion is controlled by the variable
 <a class="link" href="#flocont" title="12.2.4.1. Rule of Float Precision Contagion sec_12-1-4-4"><code class="varname">CUSTOM:*FLOATING-POINT-CONTAGION-ANSI*</code></a>.  When it is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, contagion is done as per the
 [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>]: <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SHORT-FLOAT</code></a> → <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SINGLE-FLOAT</code></a> →
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">DOUBLE-FLOAT</code></a> → <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">LONG-FLOAT</code></a>.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term">Rationale:</span></dt><dd>See it pragmatically: save what you can and let
  others worry about the rest.</dd><dt><span class="term">Brief:</span></dt><dd><a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> knows the number's <span class="emphasis"><em>precision</em></span>,
   not <span class="emphasis"><em>accuracy</em></span>, so preserving the precision can be
   accomplished reliably, while anything relating to the accuracy is
   just a speculation - only the user (programmer) knows what it is in
   each case.</dd><dt><span class="term">Detailed:</span></dt><dd>A computer float is an approximation of a real number.
  One can think of it as a random variable with the mean equal to
  itself and standard deviation equal to half the last significant digit.
  E.g., <code class="literal">1.5</code> is actually <code class="literal">1.5±0.05</code>.
  Consider adding <code class="literal">1.5</code> and <code class="literal">1.75</code>.
  [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] requires that <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_pl.html" target="_top"><code class="function">+</code></a> 1.5 1.75)</code>
  return <span class="returnvalue">3.25</span>, while traditional <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
  would return <span class="returnvalue">3.3</span>.
  The implied random variables are: <code class="literal">3.25±0.005</code>
  and <code class="literal">3.3±0.05</code>.
  Note that the traditional <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> way <span class="strong"><strong>does</strong></span>
  lie about the mean: the mean <span class="strong"><strong>is</strong></span> <code class="literal">3.25</code> and
  nothing else, while the standard way
  <span class="strong"><strong>could</strong></span> be lying about the deviation
  (accuracy): if the implied accuracy of <code class="literal">1.5</code> (i.e., 0.05)
  is its actual accuracy, then the accuracy of the result cannot be
  smaller that that.  Therefore, since <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> has no way of knowing the
  actual accuracy, [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] (and all the other standard engineering
  programming languages, like <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>, <a class="dict" href="http://foldoc.org/Fortran"><span class="command"><strong>Fortran</strong></span></a>
  etc) decided that keeping the accuracy correct is the business of the
  programmer, while the language should preserve what it can - the precision.
  </dd><dt><span class="term">Experience:</span></dt><dd>Rounding errors accumulate, and if a computation
  is conducted with insufficient precision, an outright incorrect
  result can be returned.
  (E.g., <code class="code">E(x<sup>2</sup>) -
  E(x)<sup>2</sup></code> can be negative!)
  The user should not mix floats of different precision (that's what
  <a class="link" href="#warn-fpc" title="Variable CUSTOM:*WARN-ON-FLOATING-POINT-CONTAGION*"><code class="varname">CUSTOM:*WARN-ON-FLOATING-POINT-CONTAGION*</code></a> is for), but one should not be penalized for this too
  harshly.</dd></dl></div><p>When <a class="link" href="#flocont" title="12.2.4.1. Rule of Float Precision Contagion sec_12-1-4-4"><code class="varname">CUSTOM:*FLOATING-POINT-CONTAGION-ANSI*</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the traditional <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> method is used,
 namely the result of an arithmetic operation whose arguments are of
 different float types is rounded to the float format of the shortest
 (least precise) of the arguments: <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_rational.html" target="_top"><code class="classname">RATIONAL</code></a> →
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">LONG-FLOAT</code></a> → <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">DOUBLE-FLOAT</code></a> → <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SINGLE-FLOAT</code></a>
 → <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SHORT-FLOAT</code></a> (in contrast to
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_12-1-4-4.html">[sec_12-1-4-4]</a>!)</p><div class="variablelist"><dl class="variablelist"><dt><span class="term">Rationale:</span></dt><dd>See it mathematically.  Add intervals:
  <code class="code">{1.0 ± 1e-8} + {1.0 ± 1e-16} = {2.0 ±
  1e-8}</code>.  So, if we add <code class="literal">1.0s0</code> and
  <code class="literal">1.0d0</code>, we should get <code class="literal">2.0s0</code>.
  </dd><dt><span class="term">Brief:</span></dt><dd>Do not suggest high accuracy of a result by giving
  it a precision that is greater than its accuracy.
  </dd><dt><span class="term">Example:</span></dt><dd><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_-.html" target="_top"><code class="function">-</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_pl.html" target="_top"><code class="function">+</code></a> 1.7 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_pi.html" target="_top"><code class="constant">PI</code></a>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_pi.html" target="_top"><code class="constant">PI</code></a>)</code>
  should not return <span class="returnvalue">1.700000726342836417234L0</span>,
   it should return <span class="returnvalue">1.7f0</span> (or
   <span class="returnvalue">1.700001f0</span> if there were rounding errors).
</dd><dt><span class="term">Experience:</span></dt><dd>If in a computation using thousands of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SHORT-FLOAT</code></a>s,
  a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">LONG-FLOAT</code></a> (like <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_pi.html" target="_top"><code class="constant">PI</code></a>) happens to be used, the long precision
  should not propagate throughout all the intermediate values.
  Otherwise, the long result would look precise, but its accuracy is
  only that of a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SHORT-FLOAT</code></a>; furthermore much computation time
  would be lost by calculating with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">LONG-FLOAT</code></a>s when only
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SHORT-FLOAT</code></a>s would be needed.</dd></dl></div><div class="simplesect"><div class="titlepage"><div><div><h5 class="title"><a id="warn-fpc"></a>Variable <a class="link" href="#warn-fpc" title="Variable CUSTOM:*WARN-ON-FLOATING-POINT-CONTAGION*"><code class="varname">CUSTOM:*WARN-ON-FLOATING-POINT-CONTAGION*</code></a></h5></div></div></div><p>If the variable <a class="link" href="#warn-fpc" title="Variable CUSTOM:*WARN-ON-FLOATING-POINT-CONTAGION*"><code class="varname">CUSTOM:*WARN-ON-FLOATING-POINT-CONTAGION*</code></a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_warning.html" target="_top"><code class="classname">WARNING</code></a> is emitted for
 every coercion involving different floating-point types.
 As explained above, float precision contagion is not a good idea.
 You can avoid the contagion by doing all your computations with the
 same floating-point type (and using <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_float.html" target="_top"><code class="function">FLOAT</code></a> to convert all constants,
 e.g., <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_pi.html" target="_top"><code class="constant">PI</code></a>, to your preferred type).</p><p>This variable helps you eliminate all occurrences of float
 precision contagion: set it to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> to have <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a> a
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_warning.html" target="_top"><code class="classname">WARNING</code></a> on float precision contagion; set it to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_error.html" target="_top"><code class="function">ERROR</code></a> to have
 <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a> an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> on float precision contagion, so that you
 can look at the stack <a class="link" href="#backtrace"><span class="command"><strong>backtrace</strong></span></a>.</p></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="floratcont"></a>12.2.4.2. Rule of Float and Rational Contagion
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_12-1-4-1.html">[sec_12-1-4-1]</a></h4></div></div></div><p>The contagion between floating point and rational numbers is controlled
 by the variable <a class="link" href="#floratcont" title="12.2.4.2. Rule of Float and Rational Contagion sec_12-1-4-1"><code class="varname">CUSTOM:*FLOATING-POINT-RATIONAL-CONTAGION-ANSI*</code></a>.  When it is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, contagion is done as per
 the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>]: <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_rational.html" target="_top"><code class="classname">RATIONAL</code></a> → <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_float.html" target="_top"><code class="classname">FLOAT</code></a>.</p><p>When <a class="link" href="#floratcont" title="12.2.4.2. Rule of Float and Rational Contagion sec_12-1-4-1"><code class="varname">CUSTOM:*FLOATING-POINT-RATIONAL-CONTAGION-ANSI*</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the traditional <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> method is used,
 namely if the result is mathematically an exact rational number, this
 rational number is returned (in contrast to
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_12-1-4-1.html">[sec_12-1-4-1]</a>!)</p><p><a class="link" href="#floratcont" title="12.2.4.2. Rule of Float and Rational Contagion sec_12-1-4-1"><code class="varname">CUSTOM:*FLOATING-POINT-RATIONAL-CONTAGION-ANSI*</code></a> has an effect only in those few cases when the mathematical
 result is exact although one of the arguments is a floating-point number,
 such as <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_st.html" target="_top"><code class="function">*</code></a> 0 1.618)</code>, <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_sl.html" target="_top"><code class="function">/</code></a> 0 1.618)</code>,
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_asincm_acoscm_atan.html" target="_top"><code class="function">ATAN</code></a> 0 1.0)</code>, <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_expcm_expt.html" target="_top"><code class="function">EXPT</code></a> 2.0 0)</code>,
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_phase.html" target="_top"><code class="function">PHASE</code></a> 2.718)</code>.</p><div class="simplesect"><div class="titlepage"><div><div><h5 class="title"><a id="warn-fprc"></a>Variable <a class="link" href="#warn-fprc" title="Variable CUSTOM:*WARN-ON-FLOATING-POINT-RATIONAL-CONTAGION*"><code class="varname">CUSTOM:*WARN-ON-FLOATING-POINT-RATIONAL-CONTAGION*</code></a></h5></div></div></div><p>If the variable <a class="link" href="#warn-fprc" title="Variable CUSTOM:*WARN-ON-FLOATING-POINT-RATIONAL-CONTAGION*"><code class="varname">CUSTOM:*WARN-ON-FLOATING-POINT-RATIONAL-CONTAGION*</code></a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_warning.html" target="_top"><code class="classname">WARNING</code></a> is emitted for
 every avoidable coercion from a rational number to a floating-point number.
 You can avoid such coercions by calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_float.html" target="_top"><code class="function">FLOAT</code></a> to convert the particular
 rational numbers to your preferred floating-point type.</p><p>This variable helps you eliminate all occurrences of avoidable
 coercions to a floating-point number when a rational number result
 would be possible: set it to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> to have <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a> a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_warning.html" target="_top"><code class="classname">WARNING</code></a>
 in such situations; set it to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_error.html" target="_top"><code class="function">ERROR</code></a> to have <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a> an
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> in such situations, so that you can look at the stack
 <a class="link" href="#backtrace"><span class="command"><strong>backtrace</strong></span></a>.</p></div><div class="simplesect"><div class="titlepage"><div><div><h5 class="title"><a id="phasecont"></a>Variable <a class="link" href="#phasecont" title="Variable CUSTOM:*PHASE-ANSI*"><code class="varname">CUSTOM:*PHASE-ANSI*</code></a></h5></div></div></div><p>A similar variable, <a class="link" href="#phasecont" title="Variable CUSTOM:*PHASE-ANSI*"><code class="varname">CUSTOM:*PHASE-ANSI*</code></a>, controls the return
 value of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_phase.html" target="_top"><code class="function">PHASE</code></a> when the argument is an exact nonnegative <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_real.html" target="_top"><code class="classname">REAL</code></a>.
 Namely, if <a class="link" href="#phasecont" title="Variable CUSTOM:*PHASE-ANSI*"><code class="varname">CUSTOM:*PHASE-ANSI*</code></a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, it returns a floating-point zero;
 if <a class="link" href="#phasecont" title="Variable CUSTOM:*PHASE-ANSI*"><code class="varname">CUSTOM:*PHASE-ANSI*</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, it returns an exact zero.  Example:
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_phase.html" target="_top"><code class="function">PHASE</code></a> 2/3)</code></p></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="complex-comp"></a>12.2.5. Complex Computations
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_12-1-5.html">[sec_12-1-5]</a></h3></div></div></div><p>Complex numbers can have a real part and an imaginary part of
 different types. For example, <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_sqrtcm_isqrt.html" target="_top"><code class="function">SQRT</code></a> -9.0)</code> evaluates to
 the number <span class="data"><code class="literal"><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-11.html"><span class="data"><code class="literal">#C</code></span></a>(0 3.0)</code></span>,
 which has a real part of exactly <code class="literal">0</code>,
 not only <span class="data"><code class="literal">0.0</code></span>
 (which would mean <span class="quote">“<span class="quote">approximately 0</span>”</span>).</p><p>The <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_t.html#type_specifier">type specifier</a> for this is <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_complex.html" target="_top"><code class="classname">COMPLEX</code></a>
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SINGLE-FLOAT</code></a>)</code></span>, and <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_complex.html" target="_top"><code class="classname">COMPLEX</code></a>
  <code class="varname">type-of-real-part</code>
  <code class="varname">type-of-imaginary-part</code>)</code></span> in general.</p><p>The <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_t.html#type_specifier">type specifier</a> <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_complex.html" target="_top"><code class="classname">COMPLEX</code></a>
  <em class="replaceable"><code>type</code></em>)</code></span> is equivalent to <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_complex.html" target="_top"><code class="classname">COMPLEX</code></a>
  <em class="replaceable"><code>type</code></em> <em class="replaceable"><code>type</code></em>)</code></span>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="complex-rational"></a>12.2.6. Rule of Canonical Representation
  for Complex Rationals <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_12-1-5-3.html">[sec_12-1-5-3]</a></h3></div></div></div><p>Complex numbers can have a real part and an imaginary part of
 different types.  If the imaginary part is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eql.html" target="_top"><code class="function">EQL</code></a> to <code class="literal">0</code>,
 the number is automatically converted to a real number.</p><p>This has the advantage that
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET</code></a> ((x (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_sqrtcm_isqrt.html" target="_top"><code class="function">SQRT</code></a> -9.0))) (* x x))</code> - instead of
 evaluating to <span class="data"><code class="literal"><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-11.html"><span class="data"><code class="literal">#C</code></span></a>(-9.0 0.0)</code></span>,
 with <em class="replaceable"><code>x</code></em> = <span class="data"><code class="literal"><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-11.html"><span class="data"><code class="literal">#C</code></span></a>(0.0 3.0)</code></span> -
 evaluates to <span class="data"><code class="literal"><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-11.html"><span class="data"><code class="literal">#C</code></span></a>(-9.0 0)</code></span> =
 <span class="data"><code class="literal">-9.0</code></span>,
 with <em class="replaceable"><code>x</code></em> = <span class="data"><code class="literal"><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-11.html"><span class="data"><code class="literal">#C</code></span></a>(0 3.0)</code></span>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="random-state"></a>12.2.7. Random-State Operations
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_12-1-7.html">[sec_12-1-7]</a></h3></div></div></div><p>To ease reproducibility, the variable <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_strandom-statest.html" target="_top"><code class="varname">*RANDOM-STATE*</code></a> is
 initialized to the same value on each invocation, so that
 </p><pre class="screen"><strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp.html#clisp" class="olink">clisp</a></strong></span> <code class="option"><a href="clisp.html#opt-norc" class="olink">-norc</a></code> <code class="option"><a href="clisp.html#opt-exec-expr" class="olink">-x</a></code> '(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_random.html" target="_top"><code class="function">RANDOM</code></a> 1s0)'</pre><p>
 will always print the same number.</p><p>If you want a new random state on each invocation, you can arrange
 for that by using <a href="impnotes.html#init-func" class="olink">init function</a>: </p><pre class="screen">
<strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp.html#clisp" class="olink">clisp</a></strong></span> <code class="option"><a href="clisp.html#opt-norc" class="olink">-norc</a></code> <code class="option"><a href="clisp.html#opt-exec-expr" class="olink">-x</a></code> '(<a href="impnotes.html#image" class="olink"><code class="function">EXT:SAVEINITMEM</code></a> "foo" :init-function (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_lambda.html" target="_top"><code class="function">LAMBDA</code></a> () (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/spefor_setq.html" target="_top"><code class="function">SETQ</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_strandom-statest.html" target="_top"><code class="varname">*RANDOM-STATE*</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-random-state.html" target="_top"><code class="function">MAKE-RANDOM-STATE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>))))'
<strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp.html#clisp" class="olink">clisp</a></strong></span> <code class="option"><a href="clisp.html#opt-norc" class="olink">-norc</a></code> <code class="option"><a href="clisp.html#opt-memfile" class="olink">-M</a></code> foo.mem <code class="option"><a href="clisp.html#opt-exec-expr" class="olink">-x</a></code> '(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_random.html" target="_top"><code class="function">RANDOM</code></a> 1s0)'</pre><p>
 or by placing <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/spefor_setq.html" target="_top"><code class="function">SETQ</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_strandom-statest.html" target="_top"><code class="varname">*RANDOM-STATE*</code></a>
    (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-random-state.html" target="_top"><code class="function">MAKE-RANDOM-STATE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>))</code> into your <a href="clisp.html#opt-norc" class="olink">RC file</a>.</p></div></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="characters"></a>Chapter 13. Characters
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-13.html">[chap-13]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#char-intro">13.1. Introduction to Characters   sec_13-1</a></span></dt><dd><dl><dt><span class="section"><a href="#char-code">13.1.1. Function <code class="function">CHAR-CODE</code></a></span></dt><dt><span class="section"><a href="#base-char">13.1.2. Type <code class="classname">BASE-CHAR</code></a></span></dt><dt><span class="section"><a href="#char-width">13.1.3. Function <code class="function">EXT:CHAR-WIDTH</code></a></span></dt></dl></dd><dt><span class="section"><a href="#char-sets">13.2. Character sets</a></span></dt><dt><span class="section"><a href="#char-script">13.3. Character Scripts   sec_13-1-2-1</a></span></dt><dt><span class="section"><a href="#char-attrib">13.4. Character Attributes   sec_13-1-3</a></span></dt><dd><dl><dt><span class="section"><a href="#input-char">13.4.1. Input Characters</a></span></dt></dl></dd><dt><span class="section"><a href="#graph-char">13.5. Graphic Characters   sec_13-1-4-1</a></span></dt><dt><span class="section"><a href="#alpha-char">13.6. Alphabetic Characters   sec_13-1-4-2</a></span></dt><dt><span class="section"><a href="#char-case">13.7. Characters With Case   sec_13-1-4-3</a></span></dt><dd><dl><dt><span class="section"><a href="#char-invertcase">13.7.1. Function <code class="function">EXT:CHAR-INVERTCASE</code></a></span></dt><dt><span class="section"><a href="#char-ext">13.7.2. Case of Implementation-Defined Characters   sec_13-1-4-3-4</a></span></dt></dl></dd><dt><span class="section"><a href="#num-char">13.8. Numeric Characters   sec_13-1-4-4</a></span></dt><dt><span class="section"><a href="#char-ord">13.9. Ordering of Characters   sec_13-1-6</a></span></dt><dt><span class="section"><a href="#char-names">13.10. Character Names   sec_13-1-7</a></span></dt><dt><span class="section"><a href="#clhs-newline">13.11. Treatment of Newline during Input and Output   sec_13-1-8</a></span></dt><dt><span class="section"><a href="#char-int">13.12. Character Encodings   sec_13-1-9</a></span></dt><dt><span class="section"><a href="#script-ext">13.13. Documentation of Implementation-Defined Scripts   sec_13-1-10</a></span></dt><dt><span class="section"><a href="#char-platform-dep">13.14. Platform-Dependent Characters</a></span></dt><dt><span class="section"><a href="#char-bits">13.15. Obsolete Constants</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="char-intro"></a>13.1. Introduction to Characters
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_13-1.html">[sec_13-1]</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#char-code">13.1.1. Function <code class="function">CHAR-CODE</code></a></span></dt><dt><span class="section"><a href="#base-char">13.1.2. Type <code class="classname">BASE-CHAR</code></a></span></dt><dt><span class="section"><a href="#char-width">13.1.3. Function <code class="function">EXT:CHAR-WIDTH</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="char-code"></a>13.1.1. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_char-code.html" target="_top"><code class="function">CHAR-CODE</code></a></h3></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_char-code.html" target="_top"><code class="function">CHAR-CODE</code></a> takes values from <code class="literal">0</code> (inclusive) to
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_char-code-limit.html" target="_top"><code class="constant">CHAR-CODE-LIMIT</code></a> (exclusive), i.e., the implementation
 supports exactly <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_char-code-limit.html" target="_top"><code class="constant">CHAR-CODE-LIMIT</code></a> characters.</p><div class="table"><a id="char-code-limit-table"></a><p class="title"><strong>Table 13.1. Number of characters</strong></p><div class="table-contents"><table class="table" summary="Number of characters" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">binaries built</th><th align="center"><span class="strong"><strong>without</strong></span> <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> support</th><th align="center"><span class="strong"><strong>with</strong></span> <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> support</th></tr></thead><tbody><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_char-code-limit.html" target="_top"><code class="constant">CHAR-CODE-LIMIT</code></a></td><td align="center">2<sup>8</sup> = 256</td><td align="center">17 * 2<sup>16</sup> = 1114112</td></tr></tbody></table></div></div><br class="table-break" /></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="base-char"></a>13.1.2. Type <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_base-char.html" target="_top"><code class="classname">BASE-CHAR</code></a></h3></div></div></div><p>The types <code class="classname">EXT:STRING-CHAR</code> and
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_base-char.html" target="_top"><code class="classname">BASE-CHAR</code></a> are equivalent to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>.
 <code class="classname">EXT:STRING-CHAR</code> used to be available as
 <code class="classname">STRING-CHAR</code> prior to removal from [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] by
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss026.html" target="_top">CHARACTER-PROPOSAL:2</a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="char-width"></a>13.1.3. Function <a class="link" href="#char-width" title="13.1.3. Function EXT:CHAR-WIDTH"><code class="function">EXT:CHAR-WIDTH</code></a></h3></div></div></div><p><code class="code">(<a class="link" href="#char-width" title="13.1.3. Function EXT:CHAR-WIDTH"><code class="function">EXT:CHAR-WIDTH</code></a> <em class="replaceable"><code>char</code></em>)</code> returns the number of screen
 columns occupied by <em class="replaceable"><code>char</code></em>.  The value is </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">0</span></dt><dd>for non-spacing
     characters (such as control characters and many combining
     characters);</dd><dt><span class="term">2</span></dt><dd>for double-width East
     Asian characters;</dd><dt><span class="term">1</span></dt><dd>for all other
     characters.</dd></dl></div><p>
 See also function <a class="link" href="#string-width" title="16.1.2. Function EXT:STRING-WIDTH"><code class="function">EXT:STRING-WIDTH</code></a>.
</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="char-sets"></a>13.2. Character sets</h2></div></div></div><p>The characters are ordered according to a superset of the
 <a class="link" href="#charset-ASCII">ASCII character set</a>.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep">Only in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> built <span class="strong"><strong>with</strong></span> compile-time flag <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a></span></span></span></dt><dd>More precisely, <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> uses the 21-bit <a class="ulink" href="http://www.unicode.org" target="_top">Unicode</a> <a class="ulink" href="http://www.unicode.org/unicode/reports/tr28/" target="_top">3.2</a>
 character set (ISO 10646, also known as UCS-4).
</dd></dl></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep">Only in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> built <span class="strong"><strong>without</strong></span> compile-time flag <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a></span></span></span></dt><dd><p>More precisely, <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> uses the ISO Latin-1 (ISO
 8859-1) character set:
</p><div class="informaltable"><a id="latin-1-table"></a><table class="informaltable" border="1"><colgroup><col /><col /><col /><col /><col /><col /><col /><col /><col /><col /><col /><col /><col /><col /><col /><col /><col /></colgroup><thead><tr><th align="center"> </th><th align="center">#x0</th><th align="center">#x1</th><th align="center">#x2</th><th align="center">#x3</th><th align="center">#x4</th><th align="center">#x5</th><th align="center">#x6</th><th align="center">#x7</th><th align="center">#x8</th><th align="center">#x9</th><th align="center">#xA</th><th align="center">#xB</th><th align="center">#xC</th><th align="center">#xD</th><th align="center">#xE</th><th align="center">#xF</th></tr></thead><tbody><tr><td align="center">#x00</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td></tr><tr><td align="center">#x10</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td><td align="center">**</td></tr><tr><td align="center">#x20</td><td align="center"> </td><td align="center">!</td><td align="center">"</td><td align="center">#</td><td align="center">$</td><td align="center">%</td><td align="center">&amp;</td><td align="center">'</td><td align="center">(</td><td align="center">)</td><td align="center">*</td><td align="center">+</td><td align="center">,</td><td align="center">-</td><td align="center">.</td><td align="center">/</td></tr><tr><td align="center">#x30</td><td align="center">0</td><td align="center">1</td><td align="center">2</td><td align="center">3</td><td align="center">4</td><td align="center">5</td><td align="center">6</td><td align="center">7</td><td align="center">8</td><td align="center">9</td><td align="center">:</td><td align="center">;</td><td align="center">&lt;</td><td align="center">=</td><td align="center">&gt;</td><td align="center">?</td></tr><tr><td align="center">#x40</td><td align="center">@</td><td align="center">A</td><td align="center">B</td><td align="center">C</td><td align="center">D</td><td align="center">E</td><td align="center">F</td><td align="center">G</td><td align="center">H</td><td align="center">I</td><td align="center">J</td><td align="center">K</td><td align="center">L</td><td align="center">M</td><td align="center">N</td><td align="center">O</td></tr><tr><td align="center">#x50</td><td align="center">P</td><td align="center">Q</td><td align="center">R</td><td align="center">S</td><td align="center">T</td><td align="center">U</td><td align="center">V</td><td align="center">W</td><td align="center">X</td><td align="center">Y</td><td align="center">Z</td><td align="center">[</td><td align="center">\</td><td align="center">]</td><td align="center">^</td><td align="center">_</td></tr><tr><td align="center">#x60</td><td align="center">`</td><td align="center">a</td><td align="center">b</td><td align="center">c</td><td align="center">d</td><td align="center">e</td><td align="center">f</td><td align="center">g</td><td align="center">h</td><td align="center">i</td><td align="center">j</td><td align="center">k</td><td align="center">l</td><td align="center">m</td><td align="center">n</td><td align="center">o</td></tr><tr><td align="center">#x70</td><td align="center">p</td><td align="center">q</td><td align="center">r</td><td align="center">s</td><td align="center">t</td><td align="center">u</td><td align="center">v</td><td align="center">w</td><td align="center">x</td><td align="center">y</td><td align="center">z</td><td align="center">{</td><td align="center">|</td><td align="center">}</td><td align="center">~</td><td align="center"> </td></tr><tr><td align="center">#x80</td><td align="center"> </td><td align="center"> </td><td align="center"> </td><td align="center"> </td><td align="center"> </td><td align="center"> </td><td align="center"> </td><td align="center">
   </td><td align="center"> </td><td align="center"> </td><td align="center"> </td><td align="center"> </td><td align="center"> </td><td align="center"> </td><td align="center"> </td><td align="center"> </td></tr><tr><td align="center">#x90</td><td align="center"> </td><td align="center"> </td><td align="center"> </td><td align="center"> </td><td align="center"> </td><td align="center"> </td><td align="center"> </td><td align="center">
   </td><td align="center"> </td><td align="center"> </td><td align="center"> </td><td align="center"> </td><td align="center"> </td><td align="center"> </td><td align="center"> </td><td align="center"> </td></tr><tr><td align="center">#xA0</td><td align="center"> </td><td align="center">¡</td><td align="center">¢</td><td align="center">£</td><td align="center">¤</td><td align="center">¥</td><td align="center">¦</td><td align="center">§</td><td align="center">¨</td><td align="center">©</td><td align="center">ª</td><td align="center">«</td><td align="center">¬</td><td align="center"></td><td align="center">®</td><td align="center">¯</td></tr><tr><td align="center">#xB0</td><td align="center">°</td><td align="center">±</td><td align="center">²</td><td align="center">³</td><td align="center">´</td><td align="center">µ</td><td align="center">¶</td><td align="center">·</td><td align="center">¸</td><td align="center">¹</td><td align="center">º</td><td align="center">»</td><td align="center">¼</td><td align="center">½</td><td align="center">¾</td><td align="center">¿</td></tr><tr><td align="center">#xC0</td><td align="center">À</td><td align="center">Á</td><td align="center">Â</td><td align="center">Ã</td><td align="center">Ä</td><td align="center">Å</td><td align="center">Æ</td><td align="center">Ç</td><td align="center">È</td><td align="center">É</td><td align="center">Ê</td><td align="center">Ë</td><td align="center">Ì</td><td align="center">Í</td><td align="center">Î</td><td align="center">Ï</td></tr><tr><td align="center">#xD0</td><td align="center">Ð</td><td align="center">Ñ</td><td align="center">Ò</td><td align="center">Ó</td><td align="center">Ô</td><td align="center">Õ</td><td align="center">Ö</td><td align="center">×</td><td align="center">Ø</td><td align="center">Ù</td><td align="center">Ú</td><td align="center">Û</td><td align="center">Ü</td><td align="center">Ý</td><td align="center">Þ</td><td align="center">ß</td></tr><tr><td align="center">#xE0</td><td align="center">à</td><td align="center">á</td><td align="center">â</td><td align="center">ã</td><td align="center">ä</td><td align="center">å</td><td align="center">æ</td><td align="center">ç</td><td align="center">è</td><td align="center">é</td><td align="center">ê</td><td align="center">ë</td><td align="center">ì</td><td align="center">í</td><td align="center">î</td><td align="center">ï</td></tr><tr><td align="center">#xF0</td><td align="center">ð</td><td align="center">ñ</td><td align="center">ò</td><td align="center">ó</td><td align="center">ô</td><td align="center">õ</td><td align="center">ö</td><td align="center">÷</td><td align="center">ø</td><td align="center">ù</td><td align="center">ú</td><td align="center">û</td><td align="center">ü</td><td align="center">ý</td><td align="center">þ</td><td align="center">ÿ</td></tr></tbody></table></div><p>
Here ** are control characters, not graphic
  characters.  (The characters left blank here cannot be represented in
  this character set).
</p></dd></dl></div><div class="table"><a id="standard-char-table"></a><p class="title"><strong>Table 13.2. Standard characters</strong></p><div class="table-contents"><table class="table" summary="Standard characters" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="center">character</th><th align="center">code</th></tr></thead><tbody><tr><td align="center"><span class="keysym">#\Space</span></td><td align="center"><span class="keycode">#x20</span></td></tr><tr><td align="center"><span class="keysym">#\Newline</span></td><td align="center"><span class="keycode">#x0A</span></td></tr></tbody></table></div></div><br class="table-break" /><div class="table"><a id="semi-standard-char-table"></a><p class="title"><strong>Table 13.3. Semi-standard characters</strong></p><div class="table-contents"><table class="table" summary="Semi-standard characters" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="center">character</th><th align="center">code</th></tr></thead><tbody><tr><td align="center"><span class="keysym">#\Backspace</span></td><td align="center"><span class="keycode">#x08</span></td></tr><tr><td align="center"><span class="keysym">#\Tab</span></td><td align="center"><span class="keycode">#x09</span></td></tr><tr><td align="center"><span class="keysym">#\Linefeed</span></td><td align="center"><span class="keycode">#x0A</span></td></tr><tr><td align="center"><span class="keysym">#\Page</span></td><td align="center"><span class="keycode">#x0C</span></td></tr><tr><td align="center"><span class="keysym">#\Return</span></td><td align="center"><span class="keycode">#x0D</span></td></tr></tbody></table></div></div><br class="table-break" /><p><span class="keysym">#\Newline</span> is the <a class="link" href="#newline" title="31.5.3. Line Terminators">line terminator</a>.</p><div class="table"><a id="extra-named-chars-table"></a><p class="title"><strong>Table 13.4. Additional Named Characters</strong></p><div class="table-contents"><table class="table" summary="Additional Named Characters" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="center">character</th><th align="center">code</th></tr></thead><tbody><tr><td align="center"><span class="keysym">#\Null</span></td><td align="center"><span class="keycode">#x00</span></td></tr><tr><td align="center"><span class="keysym">#\Bell</span></td><td align="center"><span class="keycode">#x07</span></td></tr><tr><td align="center"><span class="keysym">#\Escape</span></td><td align="center"><span class="keycode">#x1B</span></td></tr></tbody></table></div></div><br class="table-break" /><div class="table"><a id="ctrl-char-table"></a><p class="title"><strong>Table 13.5. Additional syntax for characters with code from
   <span class="keycode">#x00</span> to <span class="keycode">#x1F</span>:</strong></p><div class="table-contents"><table class="table" summary="Additional syntax for characters with code from&#10;   #x00 to #x1F:" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="center">character</th><th align="center">code</th></tr></thead><tbody><tr><td align="center"><span class="keysym">#\^@</span></td><td align="center"><span class="keycode">#x00</span></td></tr><tr><td align="center"><span class="keysym">#\^A</span> … <span class="keysym">#\^Z</span></td><td align="center"><span class="keycode">#x01</span> …
                   <span class="keycode">#x1A</span></td></tr><tr><td align="center"><span class="keysym">#\^[</span></td><td align="center"><span class="keycode">#x1B</span></td></tr><tr><td align="center"><span class="keysym">#\^\</span></td><td align="center"><span class="keycode">#x1C</span></td></tr><tr><td align="center"><span class="keysym">#\^]</span></td><td align="center"><span class="keycode">#x1D</span></td></tr><tr><td align="center"><span class="keysym">#\^^</span></td><td align="center"><span class="keycode">#x1E</span></td></tr><tr><td align="center"><span class="keysym">#\^_</span></td><td align="center"><span class="keycode">#x1F</span></td></tr></tbody></table></div></div><br class="table-break" /><p>See also <a class="xref" href="#sharpsign-backslash" title="2.6.1. Sharpsign Backslash sec_2-4-8-1">Section 2.6.1, “Sharpsign Backslash   sec_2-4-8-1”</a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="char-script"></a>13.3. Character Scripts
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_13-1-2-1.html">[sec_13-1-2-1]</a></h2></div></div></div><p>The only defined character script is the type <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>
 itself.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="char-attrib"></a>13.4. Character Attributes
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_13-1-3.html">[sec_13-1-3]</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#input-char">13.4.1. Input Characters</a></span></dt></dl></div><p>Characters have no implementation-defined or <a class="xref" href="#CLtL1" title="Common Lisp: the Language (1st Edition)">[<abbr class="abbrev">CLtL1</abbr>]</a> font and bit
 attributes.  All characters are simple characters.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="input-char"></a>13.4.1. Input Characters</h3></div></div></div><p>For backward compatibility, there is a class <a class="link" href="#input-char" title="13.4.1. Input Characters"><code class="classname">SYS::INPUT-CHARACTER</code></a>
 representing either a character with font and bits, or a keystroke.
 The following functions work with objects of types <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>
 and <a class="link" href="#input-char" title="13.4.1. Input Characters"><code class="classname">SYS::INPUT-CHARACTER</code></a>.
 Note that <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eql.html" target="_top"><code class="function">EQL</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_equal.html" target="_top"><code class="function">EQUAL</code></a> are equivalent to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a> on objects of type
 <a class="link" href="#input-char" title="13.4.1. Input Characters"><code class="classname">SYS::INPUT-CHARACTER</code></a>.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">EXT:CHAR-FONT-LIMIT</code> = 16</span></dt><dd>The system uses only font 0.
  </dd><dt><span class="term"><code class="constant">EXT:CHAR-BITS-LIMIT</code> = 16</span></dt><dd><p>Character bits:
    </p><div class="informaltable"><a id="bit-table"></a><table class="informaltable" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="center">key</th><th align="center">value</th></tr></thead><tbody><tr><td align="center"><code class="constant">:CONTROL</code></td><td align="center"><a class="link" href="#char-bits" title="13.15. Obsolete Constants"><code class="constant">EXT:CHAR-CONTROL-BIT</code></a></td></tr><tr><td align="center"><code class="constant">:META</code></td><td align="center"><a class="link" href="#char-bits" title="13.15. Obsolete Constants"><code class="constant">EXT:CHAR-META-BIT</code></a></td></tr><tr><td align="center"><code class="constant">:SUPER</code></td><td align="center"><a class="link" href="#char-bits" title="13.15. Obsolete Constants"><code class="constant">EXT:CHAR-SUPER-BIT</code></a></td></tr><tr><td align="center"><code class="constant">:HYPER</code></td><td align="center"><a class="link" href="#char-bits" title="13.15. Obsolete Constants"><code class="constant">EXT:CHAR-HYPER-BIT</code></a></td></tr></tbody></table></div></dd><dt><span class="term"><code class="code">(<code class="function">EXT:CHAR-FONT</code>
  <em class="replaceable"><code>object</code></em>)</code></span></dt><dd>returns the font of a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a> or <a class="link" href="#input-char" title="13.4.1. Input Characters"><code class="classname">SYS::INPUT-CHARACTER</code></a>.
  </dd><dt><span class="term"><code class="code">(<code class="function">EXT:CHAR-BITS</code>
  <em class="replaceable"><code>object</code></em>)</code></span></dt><dd>returns the bits of a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a> or <a class="link" href="#input-char" title="13.4.1. Input Characters"><code class="classname">SYS::INPUT-CHARACTER</code></a>.
  </dd><dt><span class="term"><code class="code">(<code class="function">EXT:MAKE-CHAR</code>
     <em class="replaceable"><code>char</code></em> [<em class="replaceable"><code>bits</code></em>
            [<em class="replaceable"><code>font</code></em>]])</code></span></dt><dd>returns a new <a class="link" href="#input-char" title="13.4.1. Input Characters"><code class="classname">SYS::INPUT-CHARACTER</code></a>, or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if such a
 character cannot be created.</dd><dt><span class="term"><code class="code">(<code class="function">EXT:CHAR-BIT</code>
  <em class="replaceable"><code>object</code></em> <em class="replaceable"><code>name</code></em>)</code></span></dt><dd>returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> if the named bit is set in <em class="replaceable"><code>object</code></em>,
  else <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</dd><dt><span class="term"><code class="code">(<code class="function">EXT:SET-CHAR-BIT</code>
  <em class="replaceable"><code>object</code></em> <em class="replaceable"><code>name</code></em> <em class="replaceable"><code>new-value</code></em>)</code></span></dt><dd>returns a new <a class="link" href="#input-char" title="13.4.1. Input Characters"><code class="classname">SYS::INPUT-CHARACTER</code></a> with the named bit set or
   unset, depending on the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_boolean.html" target="_top"><code class="classname">BOOLEAN</code></a> <em class="replaceable"><code>new-value</code></em>.
 </dd></dl></div><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p><a class="link" href="#input-char" title="13.4.1. Input Characters"><code class="classname">SYS::INPUT-CHARACTER</code></a> is <span class="strong"><strong>not</strong></span> a subtype of
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>.</p></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platforms only.</span></span></span></dt><dd>The system itself uses this <a class="link" href="#input-char" title="13.4.1. Input Characters"><code class="classname">SYS::INPUT-CHARACTER</code></a> type only to
 mention special keys and <span class="keycap"><strong>Control</strong></span>/<span class="keycap"><strong>Alternate</strong></span>/<span class="keycap"><strong>Shift</strong></span> key status on return from
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-char.html" target="_top"><code class="function">READ-CHAR</code></a> <a href="impnotes.html#with-kbd" class="olink"><code class="varname">EXT:*KEYBOARD-INPUT*</code></a>)</code>.</dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="graph-char"></a>13.5. Graphic Characters
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_13-1-4-1.html">[sec_13-1-4-1]</a></h2></div></div></div><p>The <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_g.html#graphic">graphic</a> characters are those <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> characters which are
 defined by the <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> standard, excluding the ranges
 <span class="keycode">U0000</span> … <span class="keycode">U001F</span> and
 <span class="keycode">U007F</span> … <span class="keycode">U009F</span>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="alpha-char"></a>13.6. Alphabetic Characters
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_13-1-4-2.html">[sec_13-1-4-2]</a></h2></div></div></div><p>The alphabetic characters are those <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> characters which are
 defined as letters by the <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> standard, e.g., the <a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a> characters
</p><div class="literallayout"><p><code class="literal">             ABCDEFGHIJKLMNOPQRSTUVWXYZ<br />
             abcdefghijklmnopqrstuvwxyz</code></p></div><p>
and the international alphabetic characters from the character set:
</p><div class="literallayout"><p><code class="literal">             ÇüéâäàåçêëèïîìÄÅÉæÆôöòûùÿÖÜßáíóúñÑªºãõØøÀÃÕ</code></p></div><p>
etc.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="char-case"></a>13.7. Characters With Case
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_13-1-4-3.html">[sec_13-1-4-3]</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#char-invertcase">13.7.1. Function <code class="function">EXT:CHAR-INVERTCASE</code></a></span></dt><dt><span class="section"><a href="#char-ext">13.7.2. Case of Implementation-Defined Characters   sec_13-1-4-3-4</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="char-invertcase"></a>13.7.1. Function <a class="link" href="#char-invertcase" title="13.7.1. Function EXT:CHAR-INVERTCASE"><code class="function">EXT:CHAR-INVERTCASE</code></a></h3></div></div></div><p><code class="code">(<a class="link" href="#char-invertcase" title="13.7.1. Function EXT:CHAR-INVERTCASE"><code class="function">EXT:CHAR-INVERTCASE</code></a> <em class="replaceable"><code>char</code></em>)</code> returns the corresponding
 character in the other case for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_charcm_schar.html" target="_top"><code class="function">CHAR</code></a>, i.e., <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_char-upca_har-downcase.html" target="_top"><code class="function">CHAR-UPCASE</code></a> for a
 lowercase character and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_char-upca_har-downcase.html" target="_top"><code class="function">CHAR-DOWNCASE</code></a> for an uppercase character; for
 a character that does not have a case attribute, the argument is returned.
 See also <a class="link" href="#string-invertcase" title="16.1.3. Functions EXT:STRING-INVERTCASE and EXT:NSTRING-INVERTCASE"><code class="function">EXT:STRING-INVERTCASE</code></a> and <a class="link" href="#string-invertcase" title="16.1.3. Functions EXT:STRING-INVERTCASE and EXT:NSTRING-INVERTCASE"><code class="function">EXT:NSTRING-INVERTCASE</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="char-ext"></a>13.7.2. Case of Implementation-Defined Characters
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_13-1-4-3-4.html">[sec_13-1-4-3-4]</a></h3></div></div></div><p>The characters with case are those <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> characters <em class="replaceable"><code>c</code></em>, for
 which the upper case mapping <em class="replaceable"><code>uc</code></em> and the lower case mapping <em class="replaceable"><code>lc</code></em>
 have the following properties:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><em class="replaceable"><code>uc</code></em> and <em class="replaceable"><code>lc</code></em> are different</li><li class="listitem"><em class="replaceable"><code>c</code></em> is one of <em class="replaceable"><code>uc</code></em> and <em class="replaceable"><code>lc</code></em></li><li class="listitem">the upper case mapping of <em class="replaceable"><code>uc</code></em> and of <em class="replaceable"><code>lc</code></em>
   is <em class="replaceable"><code>uc</code></em></li><li class="listitem">the lower case mapping of <em class="replaceable"><code>uc</code></em> and of <em class="replaceable"><code>lc</code></em>
   is <em class="replaceable"><code>lc</code></em></li></ul></div><p>The titlecase property of <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> characters has no equivalent in
 <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a>.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="num-char"></a>13.8. Numeric Characters
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_13-1-4-4.html">[sec_13-1-4-4]</a></h2></div></div></div><p>The numeric characters are those <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> characters which are
 defined as digits by the <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> standard.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="char-ord"></a>13.9. Ordering of Characters
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_13-1-6.html">[sec_13-1-6]</a></h2></div></div></div><p>The characters are ordered according to their <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> code.</p><p>The functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_chareqcm__ar-not-lessp.html" target="_top"><code class="function">CHAR-EQUAL</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_chareqcm__ar-not-lessp.html" target="_top"><code class="function">CHAR-NOT-EQUAL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_chareqcm__ar-not-lessp.html" target="_top"><code class="function">CHAR-LESSP</code></a>,
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_chareqcm__ar-not-lessp.html" target="_top"><code class="function">CHAR-GREATERP</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_chareqcm__ar-not-lessp.html" target="_top"><code class="function">CHAR-NOT-GREATERP</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_chareqcm__ar-not-lessp.html" target="_top"><code class="function">CHAR-NOT-LESSP</code></a> ignore bits and
 font attributes of their arguments.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="char-names"></a>13.10. Character Names
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_13-1-7.html">[sec_13-1-7]</a></h2></div></div></div><p>Character names of non-<a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a> characters are the names defined by
 <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a>, with spaces replaced by underscores, and converted to upper case.
 There are two exceptions, though:
 </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="keysym">#\U0001F514</span></span></dt><dd> has the name <code class="literal">UNICODE_BELL</code>,
     because the name <code class="literal">BELL</code> is already taken by the
     <a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a> control character with code 7 (the audible bell character).
   </dd><dt><span class="term"><span class="keysym">#\U0001F5CF</span></span></dt><dd>has the name <code class="literal">UNICODE_PAGE</code>,
     because the name <code class="literal">PAGE</code> is already taken by the
     <a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a> control character with code 12 (the form feed or page
   separator character).</dd></dl></div><p>
</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="clhs-newline"></a>13.11. Treatment of Newline during Input and Output
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_13-1-8.html">[sec_13-1-8]</a></h2></div></div></div><p>Newlines are written according to the stream's <a class="link" href="#encoding" title="31.5. Encodings"><code class="classname">EXT:ENCODING</code></a>, see the
 function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-external-format.html" target="_top"><code class="function">STREAM-EXTERNAL-FORMAT</code></a> and the description of <a class="link" href="#encoding" title="31.5. Encodings"><code class="classname">EXT:ENCODING</code></a>s,
 in particular, <a class="link" href="#newline" title="31.5.3. Line Terminators">line terminator</a>s.
 The default behavior is as follows:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platform only.</span></span></span></dt><dd>When writing to a file, <span class="keysym">#\Newline</span> is converted to
 <span class="keycode">CR</span>/<span class="keycode">LF</span>. (This is the usual convention on <a class="ulink" href="http://www.freedos.org/" target="_top"><span class="platform">DOS</span></a>.)
 For example, <span class="keysym">#\Return</span>+<span class="keysym">#\Newline</span> is written as <span class="keycode">CR</span>/<span class="keycode">CR</span>/<span class="keycode">LF</span>.
</dd></dl></div><p>When reading from a file, <span class="keycode">CR</span>/<span class="keycode">LF</span> is converted to <span class="keysym">#\Newline</span>
 (the usual convention on <a class="ulink" href="http://www.freedos.org/" target="_top"><span class="platform">DOS</span></a>), and <span class="keycode">CR</span> not followed by <span class="keycode">LF</span> is
 converted to <span class="keysym">#\Newline</span> as well (the usual conversion on MacOS, also used
 by some programs on <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>).
 If you do not want this, i.e., if you really want to distinguish
 <span class="keycode">LF</span>, <span class="keycode">CR</span> and <span class="keycode">CR</span>/<span class="keycode">LF</span>, you have to resort to
 binary input (function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-byte.html" target="_top"><code class="function">READ-BYTE</code></a>).</p><p><strong>Justification. </strong><a class="ulink" href="http://www.unicode.org/reports/tr13/tr13-9.html" target="_top">Unicode
  Newline Guidelines</a> say: <span class="quote">“<span class="quote">Even if you know which
  characters represents NLF on your particular platform, on input and in
  interpretation, treat CR, LF, CRLF, and NEL the same. Only on output do
  you need to distinguish between them.</span>”</span></p><p><strong>Rationale. </strong>In <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>, <span class="keysym">#\Newline</span> is identical to <span class="keysym">#\Linefeed</span>
 (which is specifically permitted by the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] in
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_13-1-7.html">[sec_13-1-7]</a> <span class="quote">“<span class="quote">Character Names</span>”</span>).
 Consider a file containing exactly this string:
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_concatenate.html" target="_top"><code class="function">CONCATENATE</code></a> '<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/any_string.html" target="_top"><code class="literal">STRING</code></a> "foo" (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_string.html" target="_top"><code class="function">STRING</code></a> <span class="keysym">#\Linefeed</span>)
  "bar" (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_string.html" target="_top"><code class="function">STRING</code></a> <span class="keysym">#\Return</span>) (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_string.html" target="_top"><code class="function">STRING</code></a> <span class="keysym">#\Linefeed</span>))</code>
 Suppose we open it with <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_open.html" target="_top"><code class="function">OPEN</code></a> "foo" <a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a> <code class="constant">:DOS</code>)</code>.
 What should <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-line.html" target="_top"><code class="function">READ-LINE</code></a> return?
 Right now, it returns <span class="returnvalue">"foo"</span>
 (the second <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-line.html" target="_top"><code class="function">READ-LINE</code></a> returns <span class="returnvalue">"bar"</span>
 and reaches <code class="literal"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#end-of-stream">end-of-stream</a></code>).
 If our i/o were <span class="quote">“<span class="quote">faithful</span>”</span>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-line.html" target="_top"><code class="function">READ-LINE</code></a> would have
 returned the string <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_concatenate.html" target="_top"><code class="function">CONCATENATE</code></a> '<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/any_string.html" target="_top"><code class="literal">STRING</code></a> "foo" (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_string.html" target="_top"><code class="function">STRING</code></a>
  <span class="keysym">#\Linefeed</span>) "bar")</code>, i.e., a string with an embedded <span class="keysym">#\Newline</span>
 between <span class="returnvalue">"foo"</span>
 and <span class="returnvalue">"bar"</span> (because a single <span class="keysym">#\Linefeed</span> is not a
 <span class="keysym">#\Newline</span> in the specified <a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a>, it will not make <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-line.html" target="_top"><code class="function">READ-LINE</code></a> return,
 but it <span class="strong"><strong>is</strong></span> a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <span class="keysym">#\Newline</span>!)  Even though the specification for
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-line.html" target="_top"><code class="function">READ-LINE</code></a> does not explicitly forbids newlines inside the returned
 string, such behavior would be quite surprising, to say the least.
 Moreover, this line (with an embedded <span class="keysym">#\Newline</span>) would be written as two
 lines (when writing to a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> with <a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a> of <code class="constant">:DOS</code>), because
 the embedded <span class="keysym">#\Newline</span> would be written as <span class="keycode">CR</span>+<span class="keycode">LF</span>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="char-int"></a>13.12. Character Encodings
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_13-1-9.html">[sec_13-1-9]</a></h2></div></div></div><p>The integer returned by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_char-int.html" target="_top"><code class="function">CHAR-INT</code></a> is the same as the character's
 code (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_char-code.html" target="_top"><code class="function">CHAR-CODE</code></a>).</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="script-ext"></a>13.13. Documentation of Implementation-Defined Scripts
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_13-1-10.html">[sec_13-1-10]</a></h2></div></div></div><p>See <a class="xref" href="#encoding" title="31.5. Encodings">Section 31.5, “Encodings”</a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="char-platform-dep"></a>13.14. Platform-Dependent Characters</h2></div></div></div><p>The characters that are not <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_g.html#graphic">graphic</a> chars and the space character
 have names:</p><div class="table"><a id="dos-win32-chars-table"></a><p class="title"><strong>Table 13.6. Additional characters (<span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platform only.</span></span>)</strong></p><div class="table-contents"><table class="table" summary="Additional characters (Win32 platform only.)" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="center">code</th><th align="center">char</th></tr></thead><tbody><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x00)</code></td><td align="center"><span class="keysym">#\Null</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x07)</code></td><td align="center"><span class="keysym">#\Bell</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x08)</code></td><td align="center"><span class="keysym">#\Backspace</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x09)</code></td><td align="center"><span class="keysym">#\Tab</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x0A)</code></td><td align="center"><span class="keysym">#\Newline</span></td><td align="center"><span class="keysym">#\Linefeed</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x0B)</code></td><td align="center"><span class="keysym">#\Code11</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x0C)</code></td><td align="center"><span class="keysym">#\Page</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x0D)</code></td><td align="center"><span class="keysym">#\Return</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x1A)</code></td><td align="center"><span class="keysym">#\Code26</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x1B)</code></td><td align="center"><span class="keysym">#\Escape</span></td><td align="center"><span class="keysym">#\Esc</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x20)</code></td><td align="center"><span class="keysym">#\Space</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x7F)</code></td><td align="center"><span class="keysym">#\Rubout</span></td></tr></tbody></table></div></div><br class="table-break" /><div class="table"><a id="unix-chars-table"></a><p class="title"><strong>Table 13.7. Additional characters (<span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> platform only.</span></span>)</strong></p><div class="table-contents"><table class="table" summary="Additional characters (UNIX platform only.)" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="center">code</th><th align="center">char</th></tr></thead><tbody><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x00)</code></td><td align="center"><span class="keysym">#\Null</span></td><td align="center"><span class="keysym">#\Nul</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x01)</code></td><td align="center"><span class="keysym">#\Soh</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x02)</code></td><td align="center"><span class="keysym">#\Stx</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x03)</code></td><td align="center"><span class="keysym">#\Etx</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x04)</code></td><td align="center"><span class="keysym">#\Eot</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x05)</code></td><td align="center"><span class="keysym">#\Enq</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x06)</code></td><td align="center"><span class="keysym">#\Ack</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x07)</code></td><td align="center"><span class="keysym">#\Bell</span></td><td align="center"><span class="keysym">#\Bel</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x08)</code></td><td align="center"><span class="keysym">#\Backspace</span></td><td align="center"><span class="keysym">#\Bs</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x09)</code></td><td align="center"><span class="keysym">#\Tab</span></td><td align="center"><span class="keysym">#\Ht</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x0A)</code></td><td align="center"><span class="keysym">#\Newline</span></td><td align="center"><span class="keysym">#\Nl</span></td><td align="center"><span class="keysym">#\Linefeed</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x0B)</code></td><td align="center"><span class="keysym">#\Vt</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x0C)</code></td><td align="center"><span class="keysym">#\Page</span></td><td align="center"><span class="keysym">#\Np</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x0D)</code></td><td align="center"><span class="keysym">#\Return</span></td><td align="center"><span class="keysym">#\Cr</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x0E)</code></td><td align="center"><span class="keysym">#\So</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x0F)</code></td><td align="center"><span class="keysym">#\Si</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x10)</code></td><td align="center"><span class="keysym">#\Dle</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x11)</code></td><td align="center"><span class="keysym">#\Dc1</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x12)</code></td><td align="center"><span class="keysym">#\Dc2</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x13)</code></td><td align="center"><span class="keysym">#\Dc3</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x14)</code></td><td align="center"><span class="keysym">#\Dc4</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x15)</code></td><td align="center"><span class="keysym">#\Nak</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x16)</code></td><td align="center"><span class="keysym">#\Syn</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x17)</code></td><td align="center"><span class="keysym">#\Etb</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x18)</code></td><td align="center"><span class="keysym">#\Can</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x19)</code></td><td align="center"><span class="keysym">#\Em</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x1A)</code></td><td align="center"><span class="keysym">#\Sub</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x1B)</code></td><td align="center"><span class="keysym">#\Escape</span></td><td align="center"><span class="keysym">#\Esc</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x1C)</code></td><td align="center"><span class="keysym">#\Fs</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x1D)</code></td><td align="center"><span class="keysym">#\Gs</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x1E)</code></td><td align="center"><span class="keysym">#\Rs</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x1F)</code></td><td align="center"><span class="keysym">#\Us</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x20)</code></td><td align="center"><span class="keysym">#\Space</span></td><td align="center"><span class="keysym">#\Sp</span></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> #x7F)</code></td><td align="center"><span class="keysym">#\Rubout</span></td><td align="center"><span class="keysym">#\Delete</span></td><td align="center"><span class="keysym">#\Del</span></td></tr></tbody></table></div></div><br class="table-break" /></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="char-bits"></a>13.15. Obsolete Constants</h2></div></div></div><div class="table"><a id="char-bits-table"></a><p class="title"><strong>Table 13.8. Character bit constants (obsolete)</strong></p><div class="table-contents"><table class="table" summary="Character bit constants (obsolete)" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="center">constant</th><th align="center">value</th></tr></thead><tbody><tr><td align="center"><a class="link" href="#char-bits" title="13.15. Obsolete Constants"><code class="constant">EXT:CHAR-CONTROL-BIT</code></a></td><td align="center">1</td></tr><tr><td align="center"><a class="link" href="#char-bits" title="13.15. Obsolete Constants"><code class="constant">EXT:CHAR-META-BIT</code></a></td><td align="center">2</td></tr><tr><td align="center"><a class="link" href="#char-bits" title="13.15. Obsolete Constants"><code class="constant">EXT:CHAR-SUPER-BIT</code></a></td><td align="center">4</td></tr><tr><td align="center"><a class="link" href="#char-bits" title="13.15. Obsolete Constants"><code class="constant">EXT:CHAR-HYPER-BIT</code></a></td><td align="center">8</td></tr></tbody></table></div></div><br class="table-break" /></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="conses"></a>Chapter 14. Conses <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-14.html">[chap-14]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#cons-list">14.1. Conses as Lists   sec_14-1-2</a></span></dt><dd><dl><dt><span class="section"><a href="#map-func">14.1.1. Mapping Functions</a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="cons-list"></a>14.1. Conses as Lists
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_14-1-2.html">[sec_14-1-2]</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#map-func">14.1.1. Mapping Functions</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="map-func"></a>14.1.1. Mapping Functions</h3></div></div></div><p><a id="mapcap"></a><strong>Function <a class="link" href="#mapcap" title="Function EXT:MAPCAP"><code class="function">EXT:MAPCAP</code></a>. </strong>The function <a class="link" href="#mapcap" title="Function EXT:MAPCAP"><code class="function">EXT:MAPCAP</code></a> is like <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_mapccm_ma_istcm_mapcon.html" target="_top"><code class="function">MAPCAN</code></a>, except that it
 concatenates the resulting lists with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_append.html" target="_top"><code class="function">APPEND</code></a> instead of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_nconc.html" target="_top"><code class="function">NCONC</code></a>:
</p><pre class="programlisting">(<a class="link" href="#mapcap" title="Function EXT:MAPCAP"><code class="function">EXT:MAPCAP</code></a> <em class="replaceable"><code>function</code></em> <em class="replaceable"><code>x<sub>1</sub></code></em> ... <em class="replaceable"><code>x<sub>n</sub></code></em>) ≡
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_apply.html" target="_top"><code class="function">APPLY</code></a> #'<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_append.html" target="_top"><code class="function">APPEND</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_mapccm_ma_istcm_mapcon.html" target="_top"><code class="function">MAPCAR</code></a> <em class="replaceable"><code>function</code></em> <em class="replaceable"><code>x<sub>1</sub></code></em> ... <em class="replaceable"><code>x<sub>n</sub></code></em>))</pre><p>
(Actually a bit more efficient that this would have been.)</p><p><a id="maplap"></a><strong>Function <a class="link" href="#mapcap" title="Function EXT:MAPCAP"><code class="function">EXT:MAPLAP</code></a>. </strong>The function <a class="link" href="#mapcap" title="Function EXT:MAPCAP"><code class="function">EXT:MAPLAP</code></a> is like <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_mapccm_ma_istcm_mapcon.html" target="_top"><code class="function">MAPCON</code></a>, except that it
 concatenates the resulting lists with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_append.html" target="_top"><code class="function">APPEND</code></a> instead of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_nconc.html" target="_top"><code class="function">NCONC</code></a>:
 </p><pre class="programlisting">(<a class="link" href="#mapcap" title="Function EXT:MAPCAP"><code class="function">EXT:MAPLAP</code></a> <em class="replaceable"><code>function</code></em> <em class="replaceable"><code>x<sub>1</sub></code></em> ... <em class="replaceable"><code>x<sub>n</sub></code></em>) ≡
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_apply.html" target="_top"><code class="function">APPLY</code></a> #'<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_append.html" target="_top"><code class="function">APPEND</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_mapccm_ma_istcm_mapcon.html" target="_top"><code class="function">MAPLIST</code></a> <em class="replaceable"><code>function</code></em> <em class="replaceable"><code>x<sub>1</sub></code></em> ... <em class="replaceable"><code>x<sub>n</sub></code></em>))</pre><p>
 (Actually a bit more efficient that this would have been.)</p></div></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="arrays"></a>Chapter 15. Arrays <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-15.html">[chap-15]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#array-elts">15.1. Array Elements   sec_15-1-1</a></span></dt></dl></div><p><strong>Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-array.html" target="_top"><code class="function">MAKE-ARRAY</code></a>. </strong><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-array.html" target="_top"><code class="function">MAKE-ARRAY</code></a> can return specialized arrays for the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_array-element-type.html" target="_top"><code class="function">ARRAY-ELEMENT-TYPE</code></a>s
 <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 2)</code></span>,
 <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 4)</code></span>,
 <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span>, <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 16)</code></span>, <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 32)</code></span>, and, of course, the required
 specializations <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_nil.html" target="_top"><code class="classname">NIL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_bit.html" target="_top"><code class="classname">BIT</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>.</p><p><strong>Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_adjust-array.html" target="_top"><code class="function">ADJUST-ARRAY</code></a> for displaced arrays. </strong>An array to which another array is displaced should not be shrunk
 (using <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_adjust-array.html" target="_top"><code class="function">ADJUST-ARRAY</code></a>) in such a way that the other array points into
 void space.  This cannot be checked at the time <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_adjust-array.html" target="_top"><code class="function">ADJUST-ARRAY</code></a> is
 called!</p><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="array-elts"></a>15.1. Array Elements
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_15-1-1.html">[sec_15-1-1]</a></h2></div></div></div><div class="table"><a id="array-limit-table"></a><p class="title"><strong>Table 15.1. Array limits</strong></p><div class="table-contents"><table class="table" summary="Array limits" border="1"><colgroup><col align="center" class="vars" /><col align="center" class="b32" /><col align="center" class="b64" /></colgroup><thead><tr><th align="center">CPU type</th><th align="center">32-bit CPU</th><th align="center">64-bit CPU</th></tr></thead><tbody><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_array-rank-limit.html" target="_top"><code class="constant">ARRAY-RANK-LIMIT</code></a></td><td colspan="2" align="center">2<sup>12</sup> = 4096</td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_array-_ension-limit.html" target="_top"><code class="constant">ARRAY-DIMENSION-LIMIT</code></a></td><td align="center">2<sup>24</sup>-1 = 16777215</td><td align="center">2<sup>32</sup>-1 = 4294967295</td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_array-_l-size-limit.html" target="_top"><code class="constant">ARRAY-TOTAL-SIZE-LIMIT</code></a></td><td align="center">2<sup>24</sup>-1 = 16777215</td><td align="center">2<sup>32</sup>-1 = 4294967295</td></tr></tbody></table></div></div><br class="table-break" /></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="strings"></a>Chapter 16. Strings <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-16.html">[chap-16]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#string-misc">16.1. Miscellaneous</a></span></dt><dd><dl><dt><span class="section"><a href="#string-comp">16.1.1. String Comparison</a></span></dt><dt><span class="section"><a href="#string-width">16.1.2. Function <code class="function">EXT:STRING-WIDTH</code></a></span></dt><dt><span class="section"><a href="#string-invertcase">16.1.3. Functions <code class="function">EXT:STRING-INVERTCASE</code>   and <code class="function">EXT:NSTRING-INVERTCASE</code></a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="string-misc"></a>16.1. Miscellaneous</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#string-comp">16.1.1. String Comparison</a></span></dt><dt><span class="section"><a href="#string-width">16.1.2. Function <code class="function">EXT:STRING-WIDTH</code></a></span></dt><dt><span class="section"><a href="#string-invertcase">16.1.3. Functions <code class="function">EXT:STRING-INVERTCASE</code>   and <code class="function">EXT:NSTRING-INVERTCASE</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="string-comp"></a>16.1.1. String Comparison</h3></div></div></div><p>String comparison (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stringeqc_ng-not-lessp.html" target="_top"><code class="function">STRING&lt;</code></a> and friends) is based on the
 function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_chareqcm__ar-not-lessp.html" target="_top"><code class="function">CHAR&lt;=</code></a> (see <a class="xref" href="#char-ord" title="13.9. Ordering of Characters sec_13-1-6">Section 13.9, “Ordering of Characters   sec_13-1-6”</a>).
 Therefore diphthongs do <span class="strong"><strong>not</strong></span> obey the usual national rules.  Example:
 <code class="literal">o &lt; oe &lt; z &lt; ö</code>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="string-width"></a>16.1.2. Function <a class="link" href="#string-width" title="16.1.2. Function EXT:STRING-WIDTH"><code class="function">EXT:STRING-WIDTH</code></a></h3></div></div></div><p><code class="code">(<a class="link" href="#string-width" title="16.1.2. Function EXT:STRING-WIDTH"><code class="function">EXT:STRING-WIDTH</code></a> <em class="replaceable"><code>string</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <em class="replaceable"><code>start</code></em>
  <em class="replaceable"><code>end</code></em>)</code> returns the number of screen columns occupied by
 <em class="replaceable"><code>string</code></em>.  This is computed as the sum of all <a class="link" href="#char-width" title="13.1.3. Function EXT:CHAR-WIDTH"><code class="function">EXT:CHAR-WIDTH</code></a>s of all
 of the <em class="replaceable"><code>string</code></em>'s characters:</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_reduce.html" target="_top"><code class="function">REDUCE</code></a> #'<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_pl.html" target="_top"><code class="function">+</code></a> <em class="replaceable"><code>string</code></em> <code class="constant">:KEY</code> #'<a class="link" href="#char-width" title="13.1.3. Function EXT:CHAR-WIDTH"><code class="function">EXT:CHAR-WIDTH</code></a>)
</pre></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="string-invertcase"></a>16.1.3. Functions <a class="link" href="#string-invertcase" title="16.1.3. Functions EXT:STRING-INVERTCASE and EXT:NSTRING-INVERTCASE"><code class="function">EXT:STRING-INVERTCASE</code></a>
  and <a class="link" href="#string-invertcase" title="16.1.3. Functions EXT:STRING-INVERTCASE and EXT:NSTRING-INVERTCASE"><code class="function">EXT:NSTRING-INVERTCASE</code></a></h3></div></div></div><p><code class="code">(<a class="link" href="#string-invertcase" title="16.1.3. Functions EXT:STRING-INVERTCASE and EXT:NSTRING-INVERTCASE"><code class="function">EXT:STRING-INVERTCASE</code></a> <em class="replaceable"><code>string</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <em class="replaceable"><code>start</code></em> <em class="replaceable"><code>end</code></em>)</code>
 and <code class="code">(<a class="link" href="#string-invertcase" title="16.1.3. Functions EXT:STRING-INVERTCASE and EXT:NSTRING-INVERTCASE"><code class="function">EXT:NSTRING-INVERTCASE</code></a> <em class="replaceable"><code>string</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <em class="replaceable"><code>start</code></em> <em class="replaceable"><code>end</code></em>)</code>
 are similar to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_string-up_g-capitalize.html" target="_top"><code class="function">STRING-UPCASE</code></a> et al: they use <a class="link" href="#char-invertcase" title="13.7.1. Function EXT:CHAR-INVERTCASE"><code class="function">EXT:CHAR-INVERTCASE</code></a> to
 invert the case of each characters in the argument string region.</p></div></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="sequences"></a>Chapter 17. Sequences
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-17.html">[chap-17]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#seq-func-ext">17.1. Additional Functions</a></span></dt><dd><dl><dt><span class="section"><a href="#trim-if">17.1.1. Function <code class="function">EXT:TRIM-IF</code></a></span></dt></dl></dd><dt><span class="section"><a href="#seq-macro-ext">17.2. Additional Macros</a></span></dt><dd><dl><dt><span class="section"><a href="#doseq">17.2.1. Macro <code class="function">EXT:DOSEQ</code></a></span></dt></dl></dd><dt><span class="section"><a href="#nreverse-nreconc">17.3. Functions <code class="function">NREVERSE</code> &amp; <code class="function">NRECONC</code></a></span></dt><dt><span class="section"><a href="#rem-del">17.4. Functions <code class="function">REMOVE</code> &amp; <code class="function">DELETE</code></a></span></dt><dt><span class="section"><a href="#sorting">17.5. Functions <code class="function">SORT</code> &amp; <code class="function">STABLE-SORT</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="seq-func-ext"></a>17.1. Additional Functions</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#trim-if">17.1.1. Function <code class="function">EXT:TRIM-IF</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="trim-if"></a>17.1.1. Function <code class="function">EXT:TRIM-IF</code></h3></div></div></div><p>Function <code class="code">(<code class="function">EXT:TRIM-IF</code> <em class="replaceable"><code>predicate</code></em>
  <em class="replaceable"><code>sequence</code></em>)</code> returns the portion of <em class="replaceable"><code>sequence</code></em> without the
 leading and trailing elements which match <em class="replaceable"><code>predicate</code></em>.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="seq-macro-ext"></a>17.2. Additional Macros</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#doseq">17.2.1. Macro <code class="function">EXT:DOSEQ</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="doseq"></a>17.2.1. Macro <a class="link" href="#doseq" title="17.2.1. Macro EXT:DOSEQ"><code class="function">EXT:DOSEQ</code></a></h3></div></div></div><p>For iteration through a sequence, a macro <a class="link" href="#doseq" title="17.2.1. Macro EXT:DOSEQ"><code class="function">EXT:DOSEQ</code></a>,
 similar to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_dolist.html" target="_top"><code class="function">DOLIST</code></a>, may be used instead of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_map.html" target="_top"><code class="function">MAP</code></a>:</p><pre class="programlisting">
(<a class="link" href="#doseq" title="17.2.1. Macro EXT:DOSEQ"><code class="function">EXT:DOSEQ</code></a> (<em class="replaceable"><code>variable</code></em> <em class="replaceable"><code>sequence-form</code></em> [<em class="replaceable"><code>result-form</code></em>])
  {<em class="replaceable"><code>declaration</code></em>}*
  {<em class="replaceable"><code>tag</code></em>|<em class="replaceable"><code>form</code></em>}*)
</pre><p><a class="link" href="#doseq" title="17.2.1. Macro EXT:DOSEQ"><code class="function">EXT:DOSEQ</code></a> forms are <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_i.html#iteration_form">iteration form</a>s.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="nreverse-nreconc"></a>17.3. Functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_reversecm_nreverse.html" target="_top"><code class="function">NREVERSE</code></a> &amp; <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_revappendcm_nreconc.html" target="_top"><code class="function">NRECONC</code></a></h2></div></div></div><p><strong>Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_reversecm_nreverse.html" target="_top"><code class="function">NREVERSE</code></a>. </strong>The result of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_reversecm_nreverse.html" target="_top"><code class="function">NREVERSE</code></a> is always <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a> to the argument.
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_reversecm_nreverse.html" target="_top"><code class="function">NREVERSE</code></a> on a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> swaps pairs of elements.
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_reversecm_nreverse.html" target="_top"><code class="function">NREVERSE</code></a> on a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> swaps the first and the last
 element and reverses the list chaining between them.</p><p><strong>Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_revappendcm_nreconc.html" target="_top"><code class="function">NRECONC</code></a>. </strong>The result of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_revappendcm_nreconc.html" target="_top"><code class="function">NRECONC</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a> to the first argument unless it is
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, in which case the result is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a> to the second argument.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="rem-del"></a>17.4. Functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_removecm__elete-if-not.html" target="_top"><code class="function">REMOVE</code></a> &amp; <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_removecm__elete-if-not.html" target="_top"><code class="function">DELETE</code></a></h2></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_removecm__elete-if-not.html" target="_top"><code class="function">REMOVE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_removecm__elete-if-not.html" target="_top"><code class="function">REMOVE-IF</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_removecm__elete-if-not.html" target="_top"><code class="function">REMOVE-IF-NOT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_remove-du_e-duplicates.html" target="_top"><code class="function">REMOVE-DUPLICATES</code></a> return
 their argument unchanged, if no element has to be removed.</p><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_removecm__elete-if-not.html" target="_top"><code class="function">DELETE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_removecm__elete-if-not.html" target="_top"><code class="function">DELETE-IF</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_removecm__elete-if-not.html" target="_top"><code class="function">DELETE-IF-NOT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_remove-du_e-duplicates.html" target="_top"><code class="function">DELETE-DUPLICATES</code></a>
 destructively modify their argument: If the argument is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>,
 the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDR</code></a> parts are modified.  If the argument is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> with
 fill pointer, the fill pointer is lowered and the remaining elements are
 compacted below the new fill pointer.</p><p><a id="count-ansi"></a><strong>Variable <a class="link" href="#count-ansi" title="Variable CUSTOM:*SEQUENCE-COUNT-ANSI*"><code class="varname">CUSTOM:*SEQUENCE-COUNT-ANSI*</code></a>. </strong>Contrary to the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] issue <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss283.html" target="_top">RANGE-OF-COUNT-KEYWORD:NIL-OR-INTEGER</a>,
 negative <code class="constant">:COUNT</code> keyword arguments are not allowed unless you set
 <a class="link" href="#count-ansi" title="Variable CUSTOM:*SEQUENCE-COUNT-ANSI*"><code class="varname">CUSTOM:*SEQUENCE-COUNT-ANSI*</code></a> to a non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> value, in which case <span class="quote">“<span class="quote">using a
 negative integer value is functionally equivalent to using a value of
 zero</span>”</span>, as per the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] issue.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="sorting"></a>17.5. Functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_sortcm_stable-sort.html" target="_top"><code class="function">SORT</code></a> &amp; <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_sortcm_stable-sort.html" target="_top"><code class="function">STABLE-SORT</code></a></h2></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_sortcm_stable-sort.html" target="_top"><code class="function">SORT</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_sortcm_stable-sort.html" target="_top"><code class="function">STABLE-SORT</code></a> accept two additional keyword arguments
 <code class="constant">:START</code> and <code class="constant">:END</code>:</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_sortcm_stable-sort.html" target="_top"><code class="function">SORT</code></a> <em class="replaceable"><code>sequence</code></em> <em class="replaceable"><code>predicate</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:KEY</code> <code class="constant">:START</code> <code class="constant">:END</code>)
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_sortcm_stable-sort.html" target="_top"><code class="function">STABLE-SORT</code></a> <em class="replaceable"><code>sequence</code></em> <em class="replaceable"><code>predicate</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:KEY</code> <code class="constant">:START</code> <code class="constant">:END</code>)
</pre><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_sortcm_stable-sort.html" target="_top"><code class="function">SORT</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_sortcm_stable-sort.html" target="_top"><code class="function">STABLE-SORT</code></a> are identical.
 They implement the mergesort algorithm.
 Worst case complexity: <code class="varname">O(n*log(n))</code> comparisons,
 where <em class="replaceable"><code>n</code></em> is the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_length.html" target="_top"><code class="function">LENGTH</code></a> of the subsequence bounded
 by the <code class="constant">:START</code> and <code class="constant">:END</code> arguments.</p></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="hash"></a>Chapter 18. Hash Tables <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-18.html">[chap-18]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#hash-mod-key">18.1. Modifying Hash Table Keys   sec_18-1-2</a></span></dt><dt><span class="section"><a href="#make-hash">18.2. Function <code class="function">MAKE-HASH-TABLE</code></a></span></dt><dd><dl><dt><span class="section"><a href="#hashtable-gc-rehash">18.2.1. Interaction between <code class="classname">HASH-TABLE</code>s and garbage-collection</a></span></dt></dl></dd><dt><span class="section"><a href="#defhash">18.3. Macro <code class="function">EXT:DEFINE-HASH-TABLE-TEST</code></a></span></dt><dt><span class="section"><a href="#ht-test">18.4. Function <code class="function">HASH-TABLE-TEST</code></a></span></dt><dt><span class="section"><a href="#dohash">18.5. Macro <code class="function">EXT:DOHASH</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="hash-mod-key"></a>18.1. Modifying Hash Table Keys
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_18-1-2.html">[sec_18-1-2]</a></h2></div></div></div><p>If you <span class="quote">“<span class="quote">visibly modify</span>”</span> a key, consequences are
 <span class="emphasis"><em>unpredictable</em></span>:</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET</code></a> ((<em class="replaceable"><code>hash-table</code></em> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-hash-table.html" target="_top"><code class="function">MAKE-HASH-TABLE</code></a> :test '<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_equalp.html" target="_top"><code class="function">EQUALP</code></a>)))
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_gethash.html" target="_top"><code class="function">GETHASH</code></a> <em class="replaceable"><code>hash-table</code></em> <em class="replaceable"><code>hash-table</code></em>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>)
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_gethash.html" target="_top"><code class="function">GETHASH</code></a> <em class="replaceable"><code>hash-table</code></em> <em class="replaceable"><code>hash-table</code></em>))
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></code> ;
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></code></pre><p>
 because <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_gethash.html" target="_top"><code class="function">GETHASH</code></a>)</code> modifies <em class="replaceable"><code>hash-table</code></em>, the very next
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_gethash.html" target="_top"><code class="function">GETHASH</code></a> does <span class="strong"><strong>not</strong></span> find it in itself.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="make-hash"></a>18.2. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-hash-table.html" target="_top"><code class="function">MAKE-HASH-TABLE</code></a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#hashtable-gc-rehash">18.2.1. Interaction between <code class="classname">HASH-TABLE</code>s and garbage-collection</a></span></dt></dl></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-hash-table.html" target="_top"><code class="function">MAKE-HASH-TABLE</code></a> accepts two additional keyword arguments
 <code class="constant">:INITIAL-CONTENTS</code> and <code class="constant">:WEAK</code>:</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-hash-table.html" target="_top"><code class="function">MAKE-HASH-TABLE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :TEST :INITIAL-CONTENTS :SIZE
                 :REHASH-SIZE :REHASH-THRESHOLD
                 :WARN-IF-NEEDS-REHASH-AFTER-GC :WEAK)
</pre><p>The <code class="constant">:TEST</code> argument can be, other than one of the symbols <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a>,
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eql.html" target="_top"><code class="function">EQL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_equal.html" target="_top"><code class="function">EQUAL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_equalp.html" target="_top"><code class="function">EQUALP</code></a>, one of the symbols <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="constant">EXT:FASTHASH-EQ</code></a> and
 <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="constant">EXT:STABLEHASH-EQ</code></a>.  Both of these tests use <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a> as the comparison
 function; they differ in their performance characteristics.
 </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="constant">EXT:FASTHASH-EQ</code></a></span></dt><dd>This uses the fastest possible hash function.
     Its drawback is that its hash codes become invalid at every <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion
     (except if all keys are <a class="link" href="#immediate-o" title="Immediate objects">immediate object</a>s),
     thus requiring a reorganization of the hash table at the first
     access after each <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion. Especially when generational <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion is used,
     which leads to frequent small <a href="impnotes.html#gc" class="olink">garbage-collect</a>ions, large hash table with this test
     can lead to scalability problems.</dd><dt><span class="term"><a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="constant">EXT:STABLEHASH-EQ</code></a></span></dt><dd>This uses a slower hash function that has the
     property that its hash codes for instances of the classes <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>,
     <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="classname">EXT:STANDARD-STABLEHASH</code></a> (subclass of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_standard-object.html" target="_top"><code class="classname">STANDARD-OBJECT</code></a>) and
     <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="classname">EXT:STRUCTURE-STABLEHASH</code></a> (subclass of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_structure-object.html" target="_top"><code class="classname">STRUCTURE-OBJECT</code></a>) are
     stable across GCs.
     This test can thus avoid the scalability problems if all keys,
     other than <a class="link" href="#immediate-o" title="Immediate objects">immediate object</a>s, are <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>, <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="classname">EXT:STANDARD-STABLEHASH</code></a> or
     <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="classname">EXT:STRUCTURE-STABLEHASH</code></a> instances.</dd></dl></div><p>
 One can recommend to use <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="constant">EXT:FASTHASH-EQ</code></a> for short-lived hash tables.
 For tables with a longer lifespan which can be big or accessed
 frequently, it is recommended to use <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="constant">EXT:STABLEHASH-EQ</code></a>, and to modify the
 objects that are used as its keys to become instances of
 <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="classname">EXT:STANDARD-STABLEHASH</code></a> or <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="classname">EXT:STRUCTURE-STABLEHASH</code></a>.
</p><p>When the symbol <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a> or the function <code class="literal">#'eq</code> is
used as a <code class="constant">:TEST</code> argument, the value of the variable
 <strong class="first"><em class="firstterm"><code class="varname">CUSTOM:*EQ-HASHFUNCTION*</code>
  <a id="eq-hashfunction" class="indexterm"></a></em></strong> is used instead.
This value must be one of <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="constant">EXT:FASTHASH-EQ</code></a>, <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="constant">EXT:STABLEHASH-EQ</code></a>.</p><p>Similarly, the <code class="constant">:TEST</code> argument can also be one
 of the symbols <code class="constant">EXT:FASTHASH-EQL</code>,
 <code class="constant">EXT:STABLEHASH-EQL</code>,
 <code class="constant">EXT:FASTHASH-EQUAL</code>,
 <code class="constant">EXT:STABLEHASH-EQUAL</code>.
 The same remarks apply as for <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="constant">EXT:FASTHASH-EQ</code></a> and <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="constant">EXT:STABLEHASH-EQ</code></a>.
 When the symbol <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eql.html" target="_top"><code class="function">EQL</code></a> or the function <code class="literal">#'eql</code> is used
 as a <code class="constant">:TEST</code> argument, the value of the variable
 <strong class="first"><em class="firstterm"><code class="varname">CUSTOM:*EQL-HASHFUNCTION*</code>
  <a id="eql-hashfunction" class="indexterm"></a></em></strong> is used
 instead; this value must be one of <code class="constant">EXT:FASTHASH-EQL</code>,
 <code class="constant">EXT:STABLEHASH-EQL</code>.
 Similarly, when the symbol <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_equal.html" target="_top"><code class="function">EQUAL</code></a> or the function <code class="literal">#'equal</code>
 is used as a <code class="constant">:TEST</code> argument, the value of the variable
 <strong class="first"><em class="firstterm"><code class="varname">CUSTOM:*EQUAL-HASHFUNCTION*</code>
  <a id="equal-hashfunction" class="indexterm"></a></em></strong> is used
 instead; this value must be one of <code class="constant">EXT:FASTHASH-EQUAL</code>,
 <code class="constant">EXT:STABLEHASH-EQUAL</code>.</p><p>The <code class="constant">:WARN-IF-NEEDS-REHASH-AFTER-GC</code> argument,
if true, causes a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_warning.html" target="_top"><code class="classname">WARNING</code></a> to be <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed when an object is stored
into the table which will force table reorganizations at the first
access of the table after each <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion.
This keyword argument can be used to check whether <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="constant">EXT:STABLEHASH-EQ</code></a>
should be preferred over <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="constant">EXT:FASTHASH-EQ</code></a> for a particular table.
Use <code class="function">HASH-TABLE-WARN-IF-NEEDS-REHASH-AFTER-GC</code>
to check and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> this parameter after the table has been created.</p><p>The <code class="constant">:INITIAL-CONTENTS</code> argument is an
 <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_a.html#association_list">association list</a> that is used to initialize the new hash table.</p><p>The <code class="constant">:REHASH-THRESHOLD</code> argument is ignored.</p><p>The <code class="constant">:WEAK</code> argument can take the following values:
 </p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> (default)</td></tr><tr><td><code class="constant">:KEY</code></td></tr><tr><td><code class="constant">:VALUE</code></td></tr><tr><td><code class="constant">:KEY-AND-VALUE</code></td></tr><tr><td><code class="constant">:KEY-OR-VALUE</code></td></tr></table><p>
and specifies whether the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a> is <span class="emphasis"><em>weak</em></span>:
if the key, value, either or both are not accessible for the <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion
purposes, i.e., if they are only accessible via weak <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a>s
and <a class="link" href="#weak-pointer" title="31.7.1. Weak Pointers"><code class="classname">EXT:WEAK-POINTER</code></a>s, it is <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed and removed from the weak
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a>.</p><p>The <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>able predicate <code class="function">EXT:HASH-TABLE-WEAK-P</code>
checks whether the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a> is weak.</p><p>Note that the only test that makes sense for weak hash tables are
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a> and its variants <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="constant">EXT:FASTHASH-EQ</code></a> and <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="constant">EXT:STABLEHASH-EQ</code></a>.</p><p>Just like all other <a class="link" href="#weak" title="31.7. Weak Objects">weak objects</a>, weak
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a>s cannot be printed readably.</p><p>See also <a class="xref" href="#weak-ht" title="31.7.9. Weak Hash Tables">Section 31.7.9, “Weak Hash Tables”</a>.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="hashtable-gc-rehash"></a>18.2.1. Interaction between <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a>s and <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion</h3></div></div></div><p>When a hash table contains keys to be compared by identity - such
 as <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_number.html" target="_top"><code class="classname">NUMBER</code></a>s in <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a>s with the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_hash-table-test.html" target="_top"><code class="function">HASH-TABLE-TEST</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a>;
 or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_cons.html" target="_top"><code class="classname">CONS</code></a>es in tables which test with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eql.html" target="_top"><code class="function">EQL</code></a>;
 or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a>s in tables which test with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eql.html" target="_top"><code class="function">EQL</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_equal.html" target="_top"><code class="function">EQUAL</code></a>;
 or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_standard-object.html" target="_top"><code class="classname">STANDARD-OBJECT</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_structure-object.html" target="_top"><code class="classname">STRUCTURE-OBJECT</code></a> instances in tables which
 test with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eql.html" target="_top"><code class="function">EQL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_equal.html" target="_top"><code class="function">EQUAL</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_equalp.html" target="_top"><code class="function">EQUALP</code></a>;
 - the hash code will in general depend on the object's address in
 memory.  Therefore it will in general be invalidated after a <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion,
 and the hash table's internal structure must be recomputed at the next
 table access.</p><p>While <code class="constant">:WARN-IF-NEEDS-REHASH-AFTER-GC</code> can help
 checking the efficiency of a particular <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a>, the variable
<strong class="first"><em class="firstterm"><a class="link" href="#hashtable-gc-rehash-warn"><code class="varname">CUSTOM:*WARN-ON-HASHTABLE-NEEDING-REHASH-AFTER-GC*</code></a>
 <a id="hashtable-gc-rehash-warn" class="indexterm"></a></em></strong>
 achieves the same effect for all <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a>s in the system at once:
 when <a class="link" href="#hashtable-gc-rehash-warn"><code class="varname">CUSTOM:*WARN-ON-HASHTABLE-NEEDING-REHASH-AFTER-GC*</code></a> is true and a
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a> needs to be rehashed after a <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion, a warning is
 issued that shows the inefficient <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a>.</p><p>What can be done to avoid the inefficiencies detected by these warnings?
 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">In many cases you can solve the problem
    by using the <code class="function">STABLEHASH</code> variant of the hash
    test.</li><li class="listitem">In other cases, namely <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_standard-object.html" target="_top"><code class="classname">STANDARD-OBJECT</code></a> or
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_structure-object.html" target="_top"><code class="classname">STRUCTURE-OBJECT</code></a> instances, you can solve the problem by making
    the key object classes inherit from <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="classname">EXT:STANDARD-STABLEHASH</code></a> or
    <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="classname">EXT:STRUCTURE-STABLEHASH</code></a>, respectively.</li><li class="listitem">In the remaining cases, you should store a hash key
    inside the object, of which you can guarantee uniqueness through
    your application (for example the ID of an object in a database, or
    the serial number of an object), and use this key as hash key
    instead of the original object.</li></ol></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="defhash"></a>18.3. Macro <a class="link" href="#defhash" title="18.3. Macro EXT:DEFINE-HASH-TABLE-TEST"><code class="function">EXT:DEFINE-HASH-TABLE-TEST</code></a></h2></div></div></div><p>You can define a new hash table test using the macro
 <a class="link" href="#defhash" title="18.3. Macro EXT:DEFINE-HASH-TABLE-TEST"><code class="function">EXT:DEFINE-HASH-TABLE-TEST</code></a>: <code class="code">(<a class="link" href="#defhash" title="18.3. Macro EXT:DEFINE-HASH-TABLE-TEST"><code class="function">EXT:DEFINE-HASH-TABLE-TEST</code></a> test-name <em class="replaceable"><code>test-function</code></em> <em class="replaceable"><code>hash-function</code></em>)</code>, after
 which <em class="replaceable"><code>name</code></em> can be passed as the <code class="constant">:TEST</code> argument to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-hash-table.html" target="_top"><code class="function">MAKE-HASH-TABLE</code></a>.
 E.g.: </p><pre class="programlisting">(<a class="link" href="#defhash" title="18.3. Macro EXT:DEFINE-HASH-TABLE-TEST"><code class="function">EXT:DEFINE-HASH-TABLE-TEST</code></a> string <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stringeqc_ng-not-lessp.html" target="_top"><code class="function">STRING=</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_sxhash.html" target="_top"><code class="function">SXHASH</code></a>)
⇒ <code class="computeroutput">STRING</code>
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-hash-table.html" target="_top"><code class="function">MAKE-HASH-TABLE</code></a> :test 'string)
⇒ <code class="computeroutput">#S(HASH-TABLE :TEST (#&lt;SYSTEM-FUNCTION STRING=&gt; . #&lt;SYSTEM-FUNCTION SXHASH&gt;))</code></pre><p>
(which is not too useful because it is equivalent to an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_equal.html" target="_top"><code class="function">EQUAL</code></a>
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a> but less efficient).</p><p>The fundamental requirement is that the <em class="replaceable"><code>test-function</code></em> and <em class="replaceable"><code>hash-function</code></em> are
 consistent: </p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_funcall.html" target="_top"><code class="function">FUNCALL</code></a> <em class="replaceable"><code>test-function</code></em> <em class="replaceable"><code>x</code></em> <em class="replaceable"><code>y</code></em>) ⇒
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eqcm_sleq__lteqcm_gteq.html" target="_top"><code class="function">=</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_funcall.html" target="_top"><code class="function">FUNCALL</code></a> <em class="replaceable"><code>hash-function</code></em> <em class="replaceable"><code>x</code></em>) (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_funcall.html" target="_top"><code class="function">FUNCALL</code></a> <em class="replaceable"><code>hash-function</code></em> <em class="replaceable"><code>y</code></em>))</pre><p>
 This means that the following definition: </p><pre class="programlisting">
(<a class="link" href="#defhash" title="18.3. Macro EXT:DEFINE-HASH-TABLE-TEST"><code class="function">EXT:DEFINE-HASH-TABLE-TEST</code></a> number <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eqcm_sleq__lteqcm_gteq.html" target="_top"><code class="function">=</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_sxhash.html" target="_top"><code class="function">SXHASH</code></a>)<strong>	; </strong><em class="lineannotation"><span class="lineannotation">broken!</span></em></pre><p>
 is <span class="strong"><strong>not</strong></span> correct because </p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eqcm_sleq__lteqcm_gteq.html" target="_top"><code class="function">=</code></a> 1 1d0)
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a></code><strong>	; </strong><em class="lineannotation"><span class="lineannotation">same object!</span></em>
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eqcm_sleq__lteqcm_gteq.html" target="_top"><code class="function">=</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_sxhash.html" target="_top"><code class="function">SXHASH</code></a> 1) (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_sxhash.html" target="_top"><code class="function">SXHASH</code></a> 1d0))
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></code><strong>	; </strong><em class="lineannotation"><span class="lineannotation">different buckets!</span></em></pre><p>
 The correct way is, e.g.: </p><pre class="programlisting">
(<a class="link" href="#defhash" title="18.3. Macro EXT:DEFINE-HASH-TABLE-TEST"><code class="function">EXT:DEFINE-HASH-TABLE-TEST</code></a> number <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eqcm_sleq__lteqcm_gteq.html" target="_top"><code class="function">=</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_lambda.html" target="_top"><code class="function">LAMBDA</code></a> (x) (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_sxhash.html" target="_top"><code class="function">SXHASH</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_coerce.html" target="_top"><code class="function">COERCE</code></a> x '<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SHORT-FLOAT</code></a>))))</pre><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>Note that <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_coerce.html" target="_top"><code class="function">COERCE</code></a>ing to a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SHORT-FLOAT</code></a> does <span class="strong"><strong>not</strong></span> cons up
  <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_f.html#fresh">fresh</a> objects while <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_coerce.html" target="_top"><code class="function">COERCE</code></a>ing to a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">DOUBLE-FLOAT</code></a> does.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ht-test"></a>18.4. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_hash-table-test.html" target="_top"><code class="function">HASH-TABLE-TEST</code></a></h2></div></div></div><p>Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_hash-table-test.html" target="_top"><code class="function">HASH-TABLE-TEST</code></a> returns either one of
 </p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="constant">EXT:FASTHASH-EQ</code></a></td><td><code class="constant">EXT:FASTHASH-EQUAL</code></td></tr><tr><td><a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="constant">EXT:STABLEHASH-EQ</code></a></td><td><code class="constant">EXT:STABLEHASH-EQUAL</code></td></tr><tr><td><code class="constant">EXT:FASTHASH-EQL</code></td><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_equalp.html" target="_top"><code class="function">EQUALP</code></a></td></tr><tr><td><code class="constant">EXT:STABLEHASH-EQL</code></td><td> </td></tr></table><p>
 (but <span class="strong"><strong>not</strong></span> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eql.html" target="_top"><code class="function">EQL</code></a> nor <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_equal.html" target="_top"><code class="function">EQUAL</code></a> anymore), or, for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a>s
 created with a user-defined <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_hash-table-test.html" target="_top"><code class="function">HASH-TABLE-TEST</code></a> (see macro <a class="link" href="#defhash" title="18.3. Macro EXT:DEFINE-HASH-TABLE-TEST"><code class="function">EXT:DEFINE-HASH-TABLE-TEST</code></a>),
 a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_cons.html" target="_top"><code class="classname">CONS</code></a> cell <span class="returnvalue">(<em class="replaceable"><code>test-function</code></em> . <em class="replaceable"><code>hash-function</code></em>)</span>.
</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="dohash"></a>18.5. Macro <a class="link" href="#dohash" title="18.5. Macro EXT:DOHASH"><code class="function">EXT:DOHASH</code></a></h2></div></div></div><p>For iteration through a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a>, a macro <a class="link" href="#dohash" title="18.5. Macro EXT:DOHASH"><code class="function">EXT:DOHASH</code></a>,
 similar to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_dolist.html" target="_top"><code class="function">DOLIST</code></a>, can be used instead of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_maphash.html" target="_top"><code class="function">MAPHASH</code></a>:</p><pre class="programlisting">
(<a class="link" href="#dohash" title="18.5. Macro EXT:DOHASH"><code class="function">EXT:DOHASH</code></a> (<em class="replaceable"><code>key-var</code></em> <em class="replaceable"><code>value-var</code></em> <em class="replaceable"><code>hash-table-form</code></em> [<em class="replaceable"><code>resultform</code></em>])
  {<em class="replaceable"><code>declaration</code></em>}*
  {<em class="replaceable"><code>tag</code></em>|<em class="replaceable"><code>form</code></em>}*)
</pre><p><a class="link" href="#dohash" title="18.5. Macro EXT:DOHASH"><code class="function">EXT:DOHASH</code></a> forms are <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_i.html#iteration_form">iteration form</a>s.</p></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="filenames"></a>Chapter 19. Filenames
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-19.html">[chap-19]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#path-components">19.1. Pathname Components   sec_19-2-1</a></span></dt><dd><dl><dt><span class="section"><a href="#path-dir-canon">19.1.1. Directory canonicalization</a></span></dt><dt><span class="section"><a href="#path-platform-specific">19.1.2. Platform-specific issues</a></span></dt></dl></dd><dt><span class="section"><a href="#unspecific">19.2. :UNSPECIFIC as a Component Value  sec_19-2-2-2-3</a></span></dt><dt><span class="section"><a href="#path-external-notation">19.3. External notation</a></span></dt><dt><span class="section"><a href="#log-path">19.4. Logical Pathnames   sec_19-3</a></span></dt><dt><span class="section"><a href="#filename-misc">19.5. Miscellaneous</a></span></dt><dd><dl><dt><span class="section"><a href="#translate-pathname">19.5.1. Function <code class="function">TRANSLATE-PATHNAME</code></a></span></dt><dt><span class="section"><a href="#translate-logpath">19.5.2. Function <code class="function">TRANSLATE-LOGICAL-PATHNAME</code></a></span></dt><dt><span class="section"><a href="#parsename">19.5.3. Function <code class="function">PARSE-NAMESTRING</code></a></span></dt><dt><span class="section"><a href="#pathmerge">19.5.4. Function <code class="function">MERGE-PATHNAMES</code></a></span></dt><dt><span class="section"><a href="#load-lpt">19.5.5. Function <code class="function">LOAD-LOGICAL-PATHNAME-TRANSLATIONS</code></a></span></dt><dt><span class="section"><a href="#absolute-pathname">19.5.6. Function <code class="function">EXT:ABSOLUTE-PATHNAME</code></a></span></dt></dl></dd></dl></div><p>For most operations, pathnames denoting files and pathnames
 denoting directories cannot be used interchangeably.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> platform only.</span></span></span></dt><dd>For example, <code class="filename">#P"foo/bar"</code> denotes
 the file <code class="filename">#P"bar"</code> in the directory <code class="filename">#P"foo"</code>,
 while <code class="filename">#P"foo/bar/"</code> denotes the subdirectory
 <code class="filename">#P"bar"</code> of the directory <code class="filename">#P"foo"</code>.
</dd><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platform only.</span></span></span></dt><dd>For example, <code class="filename">#P"foo\\bar"</code>
 denotes the file <code class="filename">#P"bar"</code> in the directory <code class="filename">#P"foo"</code>,
 while <code class="filename">#P"foo\\bar\\"</code> denotes the subdirectory
 <code class="filename">#P"bar"</code> of the directory <code class="filename">#P"foo"</code>.
</dd><dt><a id="device-prefix"></a><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> and <a class="ulink" href="http://cygwin.com/" target="_top"><span class="platform">Cygwin</span></a> platforms only.</span></span></span></dt><dd>User variable <strong class="first"><em class="firstterm"><a class="link" href="#device-prefix"><code class="varname">CUSTOM:*DEVICE-PREFIX*</code></a></em></strong>
  controls translation between <a class="ulink" href="http://cygwin.com/" target="_top"><span class="platform">Cygwin</span></a> pathnames
  (e.g., <code class="filename">#P"/cygdrive/c/gnu/clisp/"</code>) and native
  <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> pathnames (e.g., <code class="filename">#P"C:\\gnu\\clisp\\"</code>)
  When it is set to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, no translations occur and the <a class="ulink" href="http://cygwin.com/" target="_top"><span class="platform">Cygwin</span></a> port
  will not understand the native paths and the native <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> port will
  not understand the <a class="ulink" href="http://cygwin.com/" target="_top"><span class="platform">Cygwin</span></a> paths.
  When its value is a string, it is used by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_parse-namestring.html" target="_top"><code class="function">PARSE-NAMESTRING</code></a> to
  translate into the appropriate platform-specific representation,
  so that on <a class="ulink" href="http://cygwin.com/" target="_top"><span class="platform">Cygwin</span></a>, <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_parse-namestring.html" target="_top"><code class="function">PARSE-NAMESTRING</code></a> "c:/gnu/clisp/")</code>
  returns <code class="filename">#P"/cygdrive/c/gnu/clisp/"</code>,
  while on <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_parse-namestring.html" target="_top"><code class="function">PARSE-NAMESTRING</code></a> "/cygdrive/c/gnu/clisp/")</code>
  returns <code class="filename">#P"C:/gnu/clisp/"</code>.
  The initial value is <code class="literal">"cygdrive"</code>, you should edit
  <a class="link" href="#config-lisp"><code class="filename">config.lisp</code></a> to change it.</dd></dl></div><p>This is especially important for the
 <a class="link" href="#dir" title="20.3.3. Function EXT:DIR">directory-handling functions</a>.</p><div class="table"><a id="min-filename-syntax-table"></a><p class="title"><strong>Table 19.1. The minimum filename syntax that may be used portably</strong></p><div class="table-contents"><table class="table" summary="The minimum filename syntax that may be used portably" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="left">pathname</th><th align="left">meaning</th></tr></thead><tbody><tr><td align="left"><code class="filename">"xxx"</code></td><td align="left">for a file with name <em class="replaceable"><code>xxx</code></em></td></tr><tr><td align="left"><code class="filename">"xxx.yy"</code></td><td align="left">for a file with name <em class="replaceable"><code>xxx</code></em> and type
   <em class="replaceable"><code>yy</code></em></td></tr><tr><td align="left"><code class="filename">".yy"</code></td><td align="left">for a pathname with type <em class="replaceable"><code>yy</code></em> and no
    name or with name <em class="replaceable"><code>.yy</code></em> and no type,
    depending on the value of <a class="link" href="#name-type-split" title="Name/type namestring split"><code class="varname">CUSTOM:*PARSE-NAMESTRING-DOT-FILE*</code></a>.</td></tr></tbody></table></div></div><br class="table-break" /><p>Hereby <em class="replaceable"><code>xxx</code></em> denotes 1 to 8 characters,
 and <em class="replaceable"><code>yy</code></em> denotes 1 to 3 characters, each of
 which being either an alphanumeric character or the underscore
 <span class="keysym">#\_</span>.  Other properties of pathname syntax vary between
 operating systems.</p><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="path-components"></a>19.1. Pathname Components
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_19-2-1.html">[sec_19-2-1]</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#path-dir-canon">19.1.1. Directory canonicalization</a></span></dt><dt><span class="section"><a href="#path-platform-specific">19.1.2. Platform-specific issues</a></span></dt></dl></div><p>When a pathname is to be fully specified (no wildcards), that
 means that no <code class="constant">:WILD</code>, <code class="constant">:WILD-INFERIORS</code> is allowed, no wildcard
 characters are allowed in the strings, and <em class="replaceable"><code>name</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> may not
 be allowed either.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="path-dir-canon"></a>19.1.1. Directory canonicalization</h3></div></div></div><p>As permitted by the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-pathname.html" target="_top"><code class="function">MAKE-PATHNAME</code></a> specification, the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_pathname.html" target="_top"><code class="classname">PATHNAME</code></a>
 directory component is canonicalized when the pathname is constructed:
 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><code class="filename">""</code> and
    <code class="filename">"."</code> are removed</li><li class="listitem"><code class="filename">".."</code>,
    <code class="filename">"*"</code>, and <code class="filename">"**"</code> are converted
    to <code class="constant">:UP</code>, <code class="constant">:WILD</code> and <code class="constant">:WILD-INFERIORS</code>,
    respectively</li><li class="listitem">patterns <code class="filename">foo/../</code> are
    collapsed</li></ol></div><p>
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="path-platform-specific"></a>19.1.2. Platform-specific issues</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> platform only.</span></span></span></dt><dd><div class="variablelist"><p class="title"><strong>Pathname components</strong></p><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>host</code></em></span></dt><dd>always <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></dd><dt><span class="term"><em class="replaceable"><code>device</code></em></span></dt><dd>always <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></dd><dt><span class="term"><code class="code"><em class="replaceable"><code>directory</code></em> = (<em class="replaceable"><code>startpoint</code></em>
  . <em class="replaceable"><code>subdirs</code></em>)</code></span></dt><dd><div class="informaltable"><table class="informaltable" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="center">element</th><th align="center">values</th><th align="center">meaning</th></tr></thead><tbody><tr><td align="center"><em class="replaceable"><code>startpoint</code></em></td><td align="center"><code class="constant">:RELATIVE</code> | <code class="constant">:ABSOLUTE</code></td><td align="center"> </td></tr><tr><td align="center"><em class="replaceable"><code>subdirs</code></em></td><td align="center"><span class="data"><code class="literal">()</code></span> | <span class="data"><code class="literal">(<em class="replaceable"><code>subdir</code></em>
      . <em class="replaceable"><code>subdirs</code></em>)</code></span></td><td align="center"> </td></tr><tr><td align="center"><em class="replaceable"><code>subdir</code></em></td><td align="center"><code class="constant">:WILD-INFERIORS</code></td><td align="center"><code class="filename">**</code> or
     <code class="filename">...</code>, all subdirectories</td></tr><tr><td align="center"><em class="replaceable"><code>subdir</code></em></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-string.html" target="_top"><code class="classname">SIMPLE-STRING</code></a>,
     may contain wildcard characters <code class="filename">"?"</code> and
  <code class="filename">"*"</code> (may also be specified as <code class="constant">:WILD</code>)</td><td align="center"> </td></tr></tbody></table></div></dd><dt><span class="term"><em class="replaceable"><code>name</code></em><br /></span><span class="term"><em class="replaceable"><code>type</code></em></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-string.html" target="_top"><code class="classname">SIMPLE-STRING</code></a>, may contain wildcard characters <code class="filename">"?"</code> and
  <code class="filename">"*"</code> (may also be specified as <code class="constant">:WILD</code>)
 </dd><dt><span class="term"><em class="replaceable"><code>version</code></em></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> or <code class="constant">:WILD</code> or <code class="constant">:NEWEST</code>
    (after merging the defaults)</dd></dl></div><p>A <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> filename is <a class="link" href="#name-type-split" title="Name/type namestring split">split into name and type</a>.</p><div class="informaltable"><a id="unix-filename-table"></a><table class="informaltable" border="1"><colgroup><col /><col /></colgroup><tbody><tr><td align="center">External notation:</td><td align="center">
  <code class="filename">"server:sub1.typ/sub2.typ/name.typ"</code></td></tr><tr><td align="center">using defaults:</td><td align="center">
  <code class="filename">       "sub1.typ/sub2.typ/name.typ"</code></td></tr><tr><td align="center">or</td><td align="center">
  <code class="filename">                         "name.typ"</code></td></tr><tr><td align="center">or</td><td align="center">
  <code class="filename">       "sub1.typ/**/sub3.typ/x*.lisp"</code></td></tr><tr><td align="center">or similar.</td><td align="center"> </td></tr></tbody></table></div></dd></dl></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platform only.</span></span></span></dt><dd><div class="variablelist"><p class="title"><strong>Pathname components</strong></p><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>host</code></em></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-string.html" target="_top"><code class="classname">SIMPLE-STRING</code></a>, wildcard characters may
   occur but do not act as wildcards</dd><dt><span class="term"><em class="replaceable"><code>device</code></em></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> or <code class="constant">:WILD</code> or <code class="filename">A</code>|...|<code class="filename">Z</code>
 </dd><dt><span class="term"><code class="code"><em class="replaceable"><code>directory</code></em> = (<em class="replaceable"><code>startpoint</code></em>
  . <em class="replaceable"><code>subdirs</code></em>)</code></span></dt><dd><div class="informaltable"><table class="informaltable" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="center">element</th><th align="center">values</th><th align="center">meaning</th></tr></thead><tbody><tr><td align="center"><em class="replaceable"><code>startpoint</code></em></td><td align="center"><code class="constant">:RELATIVE</code> | <code class="constant">:ABSOLUTE</code></td><td align="center"> </td></tr><tr><td align="center"><em class="replaceable"><code>subdirs</code></em></td><td align="center"><span class="data"><code class="literal">()</code></span> | <span class="data"><code class="literal">(<em class="replaceable"><code>subdir</code></em>
      . <em class="replaceable"><code>subdirs</code></em>)</code></span></td><td align="center"> </td></tr><tr><td align="center"><em class="replaceable"><code>subdir</code></em></td><td align="center"><code class="constant">:WILD-INFERIORS</code></td><td align="center"><code class="filename">**</code> or
     <code class="filename">...</code>, all subdirectories</td></tr><tr><td align="center"><em class="replaceable"><code>subdir</code></em></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-string.html" target="_top"><code class="classname">SIMPLE-STRING</code></a>,
     may contain wildcard characters <code class="filename">"?"</code> and
  <code class="filename">"*"</code> (may also be specified as <code class="constant">:WILD</code>)</td><td align="center"> </td></tr></tbody></table></div></dd><dt><span class="term"><em class="replaceable"><code>name</code></em><br /></span><span class="term"><em class="replaceable"><code>type</code></em></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-string.html" target="_top"><code class="classname">SIMPLE-STRING</code></a>, may contain wildcard characters <code class="filename">"?"</code> and
  <code class="filename">"*"</code> (may also be specified as <code class="constant">:WILD</code>)
 </dd><dt><span class="term"><em class="replaceable"><code>version</code></em></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> or <code class="constant">:WILD</code> or <code class="constant">:NEWEST</code>
    (after merging the defaults)</dd></dl></div><p>If <em class="replaceable"><code>host</code></em> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, <em class="replaceable"><code>device</code></em> must be <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</p><p>A <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> filename is <a class="link" href="#name-type-split" title="Name/type namestring split">split into name and type</a>.</p><div class="informaltable"><a id="win32-filename-table"></a><table class="informaltable" border="1"><colgroup><col /><col /></colgroup><tbody><tr><td align="center">External notation:</td><td align="center"><code class="filename">"A:\sub1.typ\sub2.typ\name.typ"</code></td></tr><tr><td align="center">using defaults:</td><td align="center"><code class="filename">  "\sub1.typ\sub2.typ\name.typ"</code></td></tr><tr><td align="center">or</td><td align="center"><code class="filename">                     "name.typ"</code></td></tr><tr><td align="center">or</td><td align="center"><code class="filename">"*:\sub1.typ\**\sub3.typ\x*.lisp"</code></td></tr><tr><td align="center">or similar.</td><td align="center"> </td></tr></tbody></table></div><p>Instead of <code class="filename">"\"</code> one may use <code class="filename">"/"</code>, as usual for DOS
 calls.</p><p>If <em class="replaceable"><code>host</code></em> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and the <em class="replaceable"><code>directory</code></em>'s <em class="replaceable"><code>startpoint</code></em>
 is not <code class="constant">:ABSOLUTE</code>, <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_parse-namestring.html" target="_top"><code class="function">PARSE-NAMESTRING</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_namestrin_h-namestring.html" target="_top"><code class="function">NAMESTRING</code></a>
 <em class="replaceable"><code>pathname</code></em>))</code> will not be the same as <em class="replaceable"><code>pathname</code></em>.</p></dd></dl></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platforms only.</span></span></span></dt><dd>The wildcard characters: <code class="filename">"*"</code> matches any
 sequence of characters, <code class="filename">"?"</code> matches any one character.
 </dd></dl></div><p><a id="name-type-split"></a><strong>Name/type namestring split. </strong></p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platforms only.</span></span></span></dt><dd><p>A filename is split into name and type according to the
 following rule: </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">if there is no <code class="filename">"."</code> in the filename, then the
   <em class="replaceable"><code>name</code></em> is everything, <em class="replaceable"><code>type</code></em> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>;</li><li class="listitem">if there is a <code class="filename">"."</code>, then <em class="replaceable"><code>name</code></em> is the part
   before and <em class="replaceable"><code>type</code></em> the part after the last dot.</li><li class="listitem"><p>if the only <code class="filename">"."</code> is the first character, then
   the behavior depends on the value of the user variable
    <strong class="first"><em class="firstterm"><a class="link" href="#name-type-split" title="Name/type namestring split"><code class="varname">CUSTOM:*PARSE-NAMESTRING-DOT-FILE*</code></a></em></strong>
   which can be either
   </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:TYPE</code></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> <em class="replaceable"><code>name</code></em>, everything after the <code class="filename">"."</code>
     is the <em class="replaceable"><code>type</code></em>; or</dd><dt><span class="term"><code class="constant">:NAME</code></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> <em class="replaceable"><code>type</code></em>, everything is the
     <em class="replaceable"><code>name</code></em></dd></dl></div><p>
   </p></li></ul></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>Due to this name/type splitting rule, there are pathnames
   that cannot result from <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_parse-namestring.html" target="_top"><code class="function">PARSE-NAMESTRING</code></a>.
   To get a pathname whose type contains a dot or whose name contains a
   dot and whose type is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-pathname.html" target="_top"><code class="function">MAKE-PATHNAME</code></a> must be used.  Example:
   <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-pathname.html" target="_top"><code class="function">MAKE-PATHNAME</code></a> <code class="constant">:NAME</code> "foo.bar")</code>.</p></div></dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="unspecific"></a>19.2. :UNSPECIFIC as a Component Value
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_19-2-2-2-3.html">[sec_19-2-2-2-3]</a></h2></div></div></div><p>The symbol <code class="constant">:UNSPECIFIC</code> is not permitted as a
 pathname component for any slot of any pathname.
 It is also illegal to pass it as an argument to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-pathname.html" target="_top"><code class="function">MAKE-PATHNAME</code></a>,
 although it <span class="strong"><strong>is</strong></span> a legal argument (treated as <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>)
 to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_user-homedir-pathname.html" target="_top"><code class="function">USER-HOMEDIR-PATHNAME</code></a>.</p><p>The only use for <code class="constant">:UNSPECIFIC</code> is that it is
 returned by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_pathname-_name-version.html" target="_top"><code class="function">PATHNAME-DEVICE</code></a> for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_logical-pathname.html" target="_top"><code class="classname">LOGICAL-PATHNAME</code></a>s, as required by
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_19-3-2-1.html">[sec_19-3-2-1]</a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="path-external-notation"></a>19.3. External notation</h2></div></div></div><p>External notation of pathnames (cf. <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_parse-namestring.html" target="_top"><code class="function">PARSE-NAMESTRING</code></a> and
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_namestrin_h-namestring.html" target="_top"><code class="function">NAMESTRING</code></a>), of course without spaces, [,],{,}:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> platform only.</span></span></span></dt><dd><div class="informaltable"><a id="unix-path-external-table"></a><table class="informaltable" border="1"><colgroup><col /><col /></colgroup><tbody><tr><td align="center">[ <code class="filename">"/"</code> ]</td><td align="center"><code class="filename">"/"</code> denotes absolute pathnames</td></tr><tr><td align="center">{ <em class="replaceable"><code>name</code></em> <code class="filename">"/"</code> }</td><td align="center">each <em class="replaceable"><code>name</code></em> is a subdirectory</td></tr><tr><td align="center">[ <em class="replaceable"><code>name</code></em> [<code class="filename">"."</code> <em class="replaceable"><code>type</code></em>] ]</td><td align="center">filename with type (extension)</td></tr></tbody></table></div><p>Name and type may be <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>s of any <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_length.html" target="_top"><code class="function">LENGTH</code></a>
 (consisting of <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#printing">printing</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>s, except <code class="filename">"/"</code>).</p></dd><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platform only.</span></span></span></dt><dd><div class="informaltable"><a id="win32-path-external-table"></a><table class="informaltable" border="1"><colgroup><col /><col /></colgroup><tbody><tr><td align="center">[ [<em class="replaceable"><code>drivespec</code></em>] : ]</td><td align="center">a letter <code class="filename">"*"</code>|<code class="filename">a</code>|...|<code class="filename">z</code>|<code class="filename">A</code>|...|<code class="filename">Z</code></td></tr><tr><td align="center">{ <em class="replaceable"><code>name</code></em> [. <em class="replaceable"><code>type</code></em>] \ }</td><td align="center">each <em class="replaceable"><code>name</code></em> is a subdirectory, <code class="filename">"\"</code> may be
     replaced by <code class="filename">"/"</code></td></tr><tr><td align="center">[ <em class="replaceable"><code>name</code></em> [. <em class="replaceable"><code>type</code></em>] ]</td><td align="center">filename with type (extension)</td></tr></tbody></table></div><p>Name and type may be <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>s of any <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_length.html" target="_top"><code class="function">LENGTH</code></a>
 (consisting of <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#printing">printing</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>s, except <code class="filename">"/"</code>,
 <code class="filename">"\"</code>, <code class="filename">":"</code>).</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="log-path"></a>19.4. Logical Pathnames
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_19-3.html">[sec_19-3]</a></h2></div></div></div><p>No notes.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="filename-misc"></a>19.5. Miscellaneous</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#translate-pathname">19.5.1. Function <code class="function">TRANSLATE-PATHNAME</code></a></span></dt><dt><span class="section"><a href="#translate-logpath">19.5.2. Function <code class="function">TRANSLATE-LOGICAL-PATHNAME</code></a></span></dt><dt><span class="section"><a href="#parsename">19.5.3. Function <code class="function">PARSE-NAMESTRING</code></a></span></dt><dt><span class="section"><a href="#pathmerge">19.5.4. Function <code class="function">MERGE-PATHNAMES</code></a></span></dt><dt><span class="section"><a href="#load-lpt">19.5.5. Function <code class="function">LOAD-LOGICAL-PATHNAME-TRANSLATIONS</code></a></span></dt><dt><span class="section"><a href="#absolute-pathname">19.5.6. Function <code class="function">EXT:ABSOLUTE-PATHNAME</code></a></span></dt></dl></div><p><a id="path-des"></a><strong>Pathname Designators. </strong>When <a class="link" href="#parsename" title="19.5.3. Function PARSE-NAMESTRING"><code class="varname">CUSTOM:*PARSE-NAMESTRING-ANSI*</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a> is also treated as a
  <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#pathname_designator">pathname designator</a>,
  namely its <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_symbol-name.html" target="_top"><code class="function">SYMBOL-NAME</code></a> is converted to the
  operating system's preferred pathname case.</p><p><a id="path-match"></a><strong>Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_pathname-match-p.html" target="_top"><code class="function">PATHNAME-MATCH-P</code></a>. </strong><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_pathname-match-p.html" target="_top"><code class="function">PATHNAME-MATCH-P</code></a> does not interpret missing components as
  wild.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="translate-pathname"></a>19.5.1. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_translate-pathname.html" target="_top"><code class="function">TRANSLATE-PATHNAME</code></a></h3></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_translate-pathname.html" target="_top"><code class="function">TRANSLATE-PATHNAME</code></a> accepts three additional keyword arguments:
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_translate-pathname.html" target="_top"><code class="function">TRANSLATE-PATHNAME</code></a> <em class="replaceable"><code>source</code></em>
 <em class="replaceable"><code>from-wildname</code></em>
 <em class="replaceable"><code>to-wildname</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:ALL</code>
 <code class="constant">:MERGE</code> <code class="constant">:ABSOLUTE</code>)</code></p><p>If <code class="constant">:ALL</code> is specified and non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, a list of all resulting
 pathnames, corresponding to all matches of <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_pathname-match-p.html" target="_top"><code class="function">PATHNAME-MATCH-P</code></a>
  <em class="replaceable"><code>source</code></em> <em class="replaceable"><code>from-wildname</code></em>)</code>, is
 returned.</p><p>If <code class="constant">:MERGE</code> is specified and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, unspecified pieces of
 <em class="replaceable"><code>to-pathname</code></em> are not replaced by
 corresponding pieces of <em class="replaceable"><code>source</code></em>.</p><p>If <code class="constant">:ABSOLUTE</code> is specified and non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the returned
 pathnames are converted to absolute by merging in the current process'
 directory, therefore rendering pathnames suitable for the OS and
 external programs.  So, to pass a pathname to an external program, you
 do <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_namestrin_h-namestring.html" target="_top"><code class="function">NAMESTRING</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_translate-pathname.html" target="_top"><code class="function">TRANSLATE-PATHNAME</code></a> <em class="replaceable"><code>pathname</code></em>
 #P"" #P"" <code class="constant">:ABSOLUTE</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>))</code> or <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_namestrin_h-namestring.html" target="_top"><code class="function">NAMESTRING</code></a>
 (<a class="link" href="#absolute-pathname" title="19.5.6. Function EXT:ABSOLUTE-PATHNAME"><code class="function">EXT:ABSOLUTE-PATHNAME</code></a> <em class="replaceable"><code>pathname</code></em>))</code>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="translate-logpath"></a>19.5.2. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_translate_cal-pathname.html" target="_top"><code class="function">TRANSLATE-LOGICAL-PATHNAME</code></a></h3></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_translate_cal-pathname.html" target="_top"><code class="function">TRANSLATE-LOGICAL-PATHNAME</code></a> accepts an additional keyword
 argument <code class="constant">:ABSOLUTE</code>, similar to <a class="xref" href="#translate-pathname" title="19.5.1. Function TRANSLATE-PATHNAME">Section 19.5.1, “Function <code class="function">TRANSLATE-PATHNAME</code>”</a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="parsename"></a>19.5.3. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_parse-namestring.html" target="_top"><code class="function">PARSE-NAMESTRING</code></a></h3></div></div></div><p><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_parse-namestring.html" target="_top"><code class="function">PARSE-NAMESTRING</code></a> <em class="replaceable"><code>string</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
   <em class="replaceable"><code>host</code></em> <em class="replaceable"><code>defaults</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <em class="replaceable"><code>start</code></em> <em class="replaceable"><code>end</code></em>
   <em class="replaceable"><code>junk-allowed</code></em>)</code>
 returns a logical pathname only if <em class="replaceable"><code>host</code></em> is a
 <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_l.html#logical_host">logical host</a>
 or <em class="replaceable"><code>host</code></em> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and <em class="replaceable"><code>defaults</code></em> is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_logical-pathname.html" target="_top"><code class="classname">LOGICAL-PATHNAME</code></a>.
 To construct a logical pathname from a string, the function
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_logical-pathname.html" target="_top"><code class="function">LOGICAL-PATHNAME</code></a> can be used.</p><p>The [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] behavior of recognizing logical pathnames when
 the <em class="replaceable"><code>string</code></em> begins with some alphanumeric characters followed by a
 colon (<span class="keysym">#\:</span>) can be very confusing
 (cf. <code class="filename">"c:/autoexec.bat"</code>,
 <code class="filename">"home:.clisprc"</code> and
 <code class="filename">"prep:/pub/gnu"</code>)
 and therefore is disabled by default.
 To enable the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] behavior, you should set <a class="link" href="#parsename" title="19.5.3. Function PARSE-NAMESTRING"><code class="varname">CUSTOM:*PARSE-NAMESTRING-ANSI*</code></a> to non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
 Note that this also disables treating <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>s as <a class="link" href="#path-des" title="Pathname Designators">pathname designator</a>s.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="pathmerge"></a>19.5.4. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_merge-pathnames.html" target="_top"><code class="function">MERGE-PATHNAMES</code></a></h3></div></div></div><p><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_merge-pathnames.html" target="_top"><code class="function">MERGE-PATHNAMES</code></a> <em class="replaceable"><code>pathname</code></em>
   [<em class="replaceable"><code>default-pathname</code></em>])</code> returns a
   logical pathname only if
 <em class="replaceable"><code>default-pathname</code></em> is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_logical-pathname.html" target="_top"><code class="classname">LOGICAL-PATHNAME</code></a>.
 To construct a logical pathname from a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>, the function
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_logical-pathname.html" target="_top"><code class="function">LOGICAL-PATHNAME</code></a> can be used.</p><p>When both <em class="replaceable"><code>pathname</code></em> and <em class="replaceable"><code>default-pathname</code></em>
 are relative pathnames, the behavior depends on <a class="link" href="#pathmerge" title="19.5.4. Function MERGE-PATHNAMES"><code class="varname">CUSTOM:*MERGE-PATHNAMES-ANSI*</code></a>: when it is
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, then <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> retains its traditional behavior:
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_merge-pathnames.html" target="_top"><code class="function">MERGE-PATHNAMES</code></a> #P"x/" #P"y/")</code>
 evaluates to <code class="filename">#P"x/"</code></p><p><strong>Rationale. </strong><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_merge-pathnames.html" target="_top"><code class="function">MERGE-PATHNAMES</code></a> is used to specify default components for
 pathnames, so there is some analogy between
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_merge-pathnames.html" target="_top"><code class="function">MERGE-PATHNAMES</code></a> a b)</code> and
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_or.html" target="_top"><code class="function">OR</code></a> a b)</code>.  Obviously, putting in the
 same default a second time should do the same as putting it in once:
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_or.html" target="_top"><code class="function">OR</code></a> a b b)</code> is the same as <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_or.html" target="_top"><code class="function">OR</code></a> a b)</code>, so
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_merge-pathnames.html" target="_top"><code class="function">MERGE-PATHNAMES</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_merge-pathnames.html" target="_top"><code class="function">MERGE-PATHNAMES</code></a> a b) b)</code>
 should be the same as <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_merge-pathnames.html" target="_top"><code class="function">MERGE-PATHNAMES</code></a> a b)</code>.
</p><p>(This question actually does matter because in <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> there is no
 distinction between <span class="quote">“<span class="quote">pathnames with defaults merged-in</span>”</span> and
 <span class="quote">“<span class="quote">pathnames with defaults not yet applied</span>”</span>.)</p><p>Now, <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_merge-pathnames.html" target="_top"><code class="function">MERGE-PATHNAMES</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_merge-pathnames.html" target="_top"><code class="function">MERGE-PATHNAMES</code></a> #P"x/" #P"y/")
  #P"y/")</code> and <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_merge-pathnames.html" target="_top"><code class="function">MERGE-PATHNAMES</code></a> #P"x/" #P"y/")</code> are
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_equal.html" target="_top"><code class="function">EQUAL</code></a> in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> (when <a class="link" href="#pathmerge" title="19.5.4. Function MERGE-PATHNAMES"><code class="varname">CUSTOM:*MERGE-PATHNAMES-ANSI*</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>), but not in
 implementations that strictly follow the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>].
 In fact, the above <span class="emphasis"><em>twice-default = once-default</em></span>
 rule holds for all pathnames in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.</p><p>Conversely, when <a class="link" href="#pathmerge" title="19.5.4. Function MERGE-PATHNAMES"><code class="varname">CUSTOM:*MERGE-PATHNAMES-ANSI*</code></a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the normal [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>]
 behavior is exhibited: <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_merge-pathnames.html" target="_top"><code class="function">MERGE-PATHNAMES</code></a> #P"x/" #P"y/")</code>
 evaluates to <code class="filename">#P"y/x/"</code>.</p><p><strong>Rationale. </strong><span class="quote">“<span class="quote">merge</span>”</span> is <span class="emphasis"><em>merge</em></span> and
 not <span class="emphasis"><em>or</em></span>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="load-lpt"></a>19.5.5. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_load-logi_translations.html" target="_top"><code class="function">LOAD-LOGICAL-PATHNAME-TRANSLATIONS</code></a></h3></div></div></div><p>When the <em class="replaceable"><code>host</code></em> argument to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_load-logi_translations.html" target="_top"><code class="function">LOAD-LOGICAL-PATHNAME-TRANSLATIONS</code></a>
is not a defined logical host yet, we proceed as follows:
</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">If both <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html">environment variable</a>s
  <code class="envar">LOGICAL_HOST_<em class="replaceable"><code>host</code></em>_FROM</code> and
  <code class="envar">LOGICAL_HOST_<em class="replaceable"><code>host</code></em>_TO</code> exist, then their values
  define the map of the <em class="replaceable"><code>host</code></em>.</li><li class="listitem">If the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html">environment variable</a>
  <code class="envar">LOGICAL_HOST_<em class="replaceable"><code>host</code></em></code> exists, its value is read from,
  and the result is passed to <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_logical-p_translations.html" target="_top"><code class="function">LOGICAL-PATHNAME-TRANSLATIONS</code></a>)</code>.</li><li class="listitem">Variable <a href="impnotes.html#load-lpt" class="olink"><code class="varname">CUSTOM:*LOAD-LOGICAL-PATHNAME-TRANSLATIONS-DATABASE*</code></a> is consulted.
  Its value should be a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of files and/or directories,
  which are searched for in the <a href="impnotes.html#load-paths" class="olink"><code class="varname">CUSTOM:*LOAD-PATHS*</code></a>, just like for <a href="impnotes.html#loadfile" class="olink"><code class="function">LOAD</code></a>.
  When the element is a file, it is repeatedly <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_readcm_re_g-whitespace.html" target="_top"><code class="function">READ</code></a> from,
  <a class="ulink" href="http://www.franz.com/support/documentation/6.0/doc/pathnames.htm#load-logical-pathname-translations-2" target="_top">Allegro CL-style</a>,
  odd objects being host names and even object being their
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_logical-p_translations.html" target="_top"><code class="function">LOGICAL-PATHNAME-TRANSLATIONS</code></a>.
  When the element is a directory, a file, named <code class="filename"><em class="replaceable"><code>host</code></em></code>
  or <code class="filename"><em class="replaceable"><code>host</code></em>.host</code>, in that directory, is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_readcm_re_g-whitespace.html" target="_top"><code class="function">READ</code></a>
from once, <a class="ulink" href="http://common-lisp.net/project/cmucl/doc/cmu-user/extensions.html#logical-pathnames" target="_top">CMUCL-style</a>,
  the object read being the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_logical-p_translations.html" target="_top"><code class="function">LOGICAL-PATHNAME-TRANSLATIONS</code></a> of the
  <em class="replaceable"><code>host</code></em>.</li></ol></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="absolute-pathname"></a>19.5.6. Function <a class="link" href="#absolute-pathname" title="19.5.6. Function EXT:ABSOLUTE-PATHNAME"><code class="function">EXT:ABSOLUTE-PATHNAME</code></a></h3></div></div></div><p><code class="code">(<a class="link" href="#absolute-pathname" title="19.5.6. Function EXT:ABSOLUTE-PATHNAME"><code class="function">EXT:ABSOLUTE-PATHNAME</code></a> <em class="replaceable"><code>pathname</code></em>)</code> converts the <em class="replaceable"><code>pathname</code></em>
 to a physical pathname, then - if its directory component is not
 absolute - converts it to an absolute pathname, by merging in the
 current process' directory. This is like <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_truename.html" target="_top"><code class="function">TRUENAME</code></a>, except that it
 does not verify that a file named by the <em class="replaceable"><code>pathname</code></em> exists, not even that
 its directory exists. It does no filesystem accesses, except to
 determine the current directory. This function is useful when you want
 to save a pathname over time, or pass a pathname to an external
 program.</p></div></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="files"></a>Chapter 20. Files <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-20.html">[chap-20]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#dir-is-not-file">20.1. Directory is <span class="strong"><strong>not</strong></span> a file</a></span></dt><dd><dl><dt><span class="section"><a href="#probe-path">20.1.1. Function <code class="function">EXT:PROBE-PATHNAME</code></a></span></dt></dl></dd><dt><span class="section"><a href="#file-func">20.2. File functions</a></span></dt><dd><dl><dt><span class="section"><a href="#probe-file">20.2.1. Function <code class="function">PROBE-FILE</code></a></span></dt><dt><span class="section"><a href="#file-author">20.2.2. Function <code class="function">FILE-AUTHOR</code></a></span></dt><dt><span class="section"><a href="#del-file">20.2.3. Function <code class="function">DELETE-FILE</code></a></span></dt><dt><span class="section"><a href="#rename-file">20.2.4. Function <code class="function">RENAME-FILE</code></a></span></dt></dl></dd><dt><span class="section"><a href="#dir-func">20.3. Directory functions</a></span></dt><dd><dl><dt><span class="section"><a href="#probe-dir">20.3.1. Function <code class="function">EXT:PROBE-DIRECTORY</code></a></span></dt><dt><span class="section"><a href="#directory">20.3.2. Function <code class="function">DIRECTORY</code></a></span></dt><dt><span class="section"><a href="#dir">20.3.3. Function <code class="function">EXT:DIR</code></a></span></dt><dt><span class="section"><a href="#cd">20.3.4. Function <code class="function">EXT:CD</code></a></span></dt><dt><span class="section"><a href="#default-dir">20.3.5. Function <code class="function">EXT:DEFAULT-DIRECTORY</code></a></span></dt><dt><span class="section"><a href="#make-dir">20.3.6. Function <code class="function">EXT:MAKE-DIRECTORY</code></a></span></dt><dt><span class="section"><a href="#delete-dir">20.3.7. Function <code class="function">EXT:DELETE-DIRECTORY</code></a></span></dt><dt><span class="section"><a href="#rename-dir">20.3.8. Function <code class="function">EXT:RENAME-DIRECTORY</code></a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="dir-is-not-file"></a>20.1. Directory is <span class="strong"><strong>not</strong></span> a file</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#probe-path">20.1.1. Function <code class="function">EXT:PROBE-PATHNAME</code></a></span></dt></dl></div><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> has traditionally taken the view that a directory is a
 separate object and <span class="strong"><strong>not</strong></span> a special kind of file, so whenever the
 standard says that a function operates on <span class="emphasis"><em>files</em></span>
 without specifically mentioning that it also works on
 <span class="emphasis"><em>directories</em></span>, <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> when passed a
 directory.</p><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> provides separate directory functions, such as
 <a class="link" href="#delete-dir" title="20.3.7. Function EXT:DELETE-DIRECTORY"><code class="function">EXT:DELETE-DIRECTORY</code></a>, <a class="link" href="#rename-dir" title="20.3.8. Function EXT:RENAME-DIRECTORY"><code class="function">EXT:RENAME-DIRECTORY</code></a> et al.</p><p>You can use <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_directory.html" target="_top"><code class="function">DIRECTORY</code></a> or <a class="link" href="#probe-path" title="20.1.1. Function EXT:PROBE-PATHNAME"><code class="function">EXT:PROBE-PATHNAME</code></a> to figure out whether a
 given namestring refers to a file or a directory.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="probe-path"></a>20.1.1. Function <a class="link" href="#probe-path" title="20.1.1. Function EXT:PROBE-PATHNAME"><code class="function">EXT:PROBE-PATHNAME</code></a></h3></div></div></div><p>Function <code class="code">(<a class="link" href="#probe-path" title="20.1.1. Function EXT:PROBE-PATHNAME"><code class="function">EXT:PROBE-PATHNAME</code></a> <em class="replaceable"><code>pathname</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> (<code class="constant">:ERROR</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>))</code>
 figures out whether the argument refers to an existing directory or an
 existing regular file, and returns 4 values
 if the filesystem object exists: </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_truename.html" target="_top"><code class="function">TRUENAME</code></a></li><li class="listitem"><a class="link" href="#absolute-pathname" title="19.5.6. Function EXT:ABSOLUTE-PATHNAME"><code class="function">EXT:ABSOLUTE-PATHNAME</code></a></li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_file-write-date.html" target="_top"><code class="function">FILE-WRITE-DATE</code></a></li><li class="listitem"><a class="link" href="#file-size"><code class="function">POSIX:FILE-SIZE</code></a></li></ol></div><p> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if it does not exist.
 E.g., if you have a file <em class="replaceable"><code>file</code></em>, a directory <em class="replaceable"><code>directory</code></em>,
 a symbolic link <code class="filename">link-file</code> pointing to <em class="replaceable"><code>file</code></em>
 and a symbolic link <code class="filename">link-dir</code> pointing to <em class="replaceable"><code>directory</code></em>,
 then</p><pre class="programlisting">
(<a class="link" href="#probe-path" title="20.1.1. Function EXT:PROBE-PATHNAME"><code class="function">EXT:PROBE-PATHNAME</code></a> #P"filename")
⇒ <code class="computeroutput">#P"/.../filename"</code>
⇒ <code class="computeroutput">#P"/.../filename"</code>
⇒ <code class="computeroutput">3427467015</code>
⇒ <code class="computeroutput">3171976</code>
(<a class="link" href="#probe-path" title="20.1.1. Function EXT:PROBE-PATHNAME"><code class="function">EXT:PROBE-PATHNAME</code></a> #P"filename/")
⇒ <code class="computeroutput">#P"/.../filename"</code>
⇒ <code class="computeroutput">#P"/.../filename"</code>
⇒ <code class="computeroutput">3427467015</code>
⇒ <code class="computeroutput">3171976</code>
(<a class="link" href="#probe-path" title="20.1.1. Function EXT:PROBE-PATHNAME"><code class="function">EXT:PROBE-PATHNAME</code></a> #P"directory")
⇒ <code class="computeroutput">#P"/.../directory/"</code>
⇒ <code class="computeroutput">#P"/.../directory/"</code>
⇒ <code class="computeroutput">3426940352</code>
⇒ <code class="computeroutput">1024</code>
(<a class="link" href="#probe-path" title="20.1.1. Function EXT:PROBE-PATHNAME"><code class="function">EXT:PROBE-PATHNAME</code></a> #P"directory/")
⇒ <code class="computeroutput">#P"/.../directory/"</code>
⇒ <code class="computeroutput">#P"/.../directory/"</code>
⇒ <code class="computeroutput">3426940352</code>
⇒ <code class="computeroutput">1024</code>
(<a class="link" href="#probe-path" title="20.1.1. Function EXT:PROBE-PATHNAME"><code class="function">EXT:PROBE-PATHNAME</code></a> #P"link-file")
⇒ <code class="computeroutput">#P"/.../filename"</code>
⇒ <code class="computeroutput">#P"/.../link-file"</code>
⇒ <code class="computeroutput">3427467015</code>
⇒ <code class="computeroutput">3171976</code>
(<a class="link" href="#probe-path" title="20.1.1. Function EXT:PROBE-PATHNAME"><code class="function">EXT:PROBE-PATHNAME</code></a> #P"link-file/")
⇒ <code class="computeroutput">#P"/.../filename"</code>
⇒ <code class="computeroutput">#P"/.../link-file"</code>
⇒ <code class="computeroutput">3427467015</code>
⇒ <code class="computeroutput">3171976</code>
(<a class="link" href="#probe-path" title="20.1.1. Function EXT:PROBE-PATHNAME"><code class="function">EXT:PROBE-PATHNAME</code></a> #P"link-dir")
⇒ <code class="computeroutput">#P"/.../directory/"</code>
⇒ <code class="computeroutput">#P"/.../link-dir/"</code>
⇒ <code class="computeroutput">3426940352</code>
⇒ <code class="computeroutput">1024</code>
(<a class="link" href="#probe-path" title="20.1.1. Function EXT:PROBE-PATHNAME"><code class="function">EXT:PROBE-PATHNAME</code></a> #P"link-dir/")
⇒ <code class="computeroutput">#P"/.../directory/"</code>
⇒ <code class="computeroutput">#P"/.../link-dir/"</code>
⇒ <code class="computeroutput">3426940352</code>
⇒ <code class="computeroutput">1024</code>
</pre><p>This function may also <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> if, e.g., its argument resides
under a tree for which you do not have sufficient access privileges;
unless <code class="constant">:ERROR</code> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, in which case <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> is returned instead.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="file-func"></a>20.2. File functions</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#probe-file">20.2.1. Function <code class="function">PROBE-FILE</code></a></span></dt><dt><span class="section"><a href="#file-author">20.2.2. Function <code class="function">FILE-AUTHOR</code></a></span></dt><dt><span class="section"><a href="#del-file">20.2.3. Function <code class="function">DELETE-FILE</code></a></span></dt><dt><span class="section"><a href="#rename-file">20.2.4. Function <code class="function">RENAME-FILE</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="probe-file"></a>20.2.1. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_probe-file.html" target="_top"><code class="function">PROBE-FILE</code></a></h3></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_probe-file.html" target="_top"><code class="function">PROBE-FILE</code></a> cannot be used to check whether a directory exists.
 Use functions <a class="link" href="#probe-dir" title="20.3.1. Function EXT:PROBE-DIRECTORY"><code class="function">EXT:PROBE-DIRECTORY</code></a>, <a class="link" href="#probe-path" title="20.1.1. Function EXT:PROBE-PATHNAME"><code class="function">EXT:PROBE-PATHNAME</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_directory.html" target="_top"><code class="function">DIRECTORY</code></a> for this.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="file-author"></a>20.2.2. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_file-author.html" target="_top"><code class="function">FILE-AUTHOR</code></a></h3></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_file-author.html" target="_top"><code class="function">FILE-AUTHOR</code></a> always returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, because the operating systems
 <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> is ported to do not store a file's author in the file system.
 Some operating systems, such as <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, have the notion of a file's
 <span class="emphasis"><em>owner</em></span>, and some other <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> implementations return
 the user name of the file owner.  <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> does not do this, because
 <span class="emphasis"><em>owner</em></span> and <span class="emphasis"><em>author</em></span> are not the
 same; in particular, authorship is preserved by copying, while
 ownership is not.</p><p>Use <a class="link" href="#file-owner"><code class="function">OS:FILE-OWNER</code></a>
 to find the owner of the file.  See also
 <a class="link" href="#file-properties"><code class="function">OS:FILE-PROPERTIES</code></a>
 (<span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platform only.</span></span>).</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="del-file"></a>20.2.3. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_delete-file.html" target="_top"><code class="function">DELETE-FILE</code></a></h3></div></div></div><p><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_delete-file.html" target="_top"><code class="function">DELETE-FILE</code></a> <em class="replaceable"><code>pathname</code></em>)</code> deletes the pathname
 <em class="replaceable"><code>pathname</code></em>, not its <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_truename.html" target="_top"><code class="function">TRUENAME</code></a>, and returns the absolute pathname it
 actually removed or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if <em class="replaceable"><code>pathname</code></em> did not exist.
 When <em class="replaceable"><code>pathname</code></em> points to a file which is currently open in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>,
 an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.
 To remove a directory, use <a class="link" href="#delete-dir" title="20.3.7. Function EXT:DELETE-DIRECTORY"><code class="function">EXT:DELETE-DIRECTORY</code></a> instead.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="rename-file"></a>20.2.4. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_rename-file.html" target="_top"><code class="function">RENAME-FILE</code></a></h3></div></div></div><p>This functions accepts and extra keyword argument <code class="constant">:IF-EXISTS</code>.
 When it is <code class="constant">:ERROR</code> (the default), an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if the destination
 pathname names an existing file, otherwise (e.g., if it is <code class="constant">:OVERWRITE</code>)
 the destination file atomically overwritten.</p><p>When <a href="impnotes.html#ansi" class="olink"><code class="varname">CUSTOM:*ANSI*</code></a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, only the standard two arguments are accepted,
 and and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed when the destination pathname names an existing file.</p><p>This function cannot operate on directories,
 use <a class="link" href="#rename-dir" title="20.3.8. Function EXT:RENAME-DIRECTORY"><code class="function">EXT:RENAME-DIRECTORY</code></a> to rename a directory.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="dir-func"></a>20.3. Directory functions</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#probe-dir">20.3.1. Function <code class="function">EXT:PROBE-DIRECTORY</code></a></span></dt><dt><span class="section"><a href="#directory">20.3.2. Function <code class="function">DIRECTORY</code></a></span></dt><dt><span class="section"><a href="#dir">20.3.3. Function <code class="function">EXT:DIR</code></a></span></dt><dt><span class="section"><a href="#cd">20.3.4. Function <code class="function">EXT:CD</code></a></span></dt><dt><span class="section"><a href="#default-dir">20.3.5. Function <code class="function">EXT:DEFAULT-DIRECTORY</code></a></span></dt><dt><span class="section"><a href="#make-dir">20.3.6. Function <code class="function">EXT:MAKE-DIRECTORY</code></a></span></dt><dt><span class="section"><a href="#delete-dir">20.3.7. Function <code class="function">EXT:DELETE-DIRECTORY</code></a></span></dt><dt><span class="section"><a href="#rename-dir">20.3.8. Function <code class="function">EXT:RENAME-DIRECTORY</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="probe-dir"></a>20.3.1. Function <a class="link" href="#probe-dir" title="20.3.1. Function EXT:PROBE-DIRECTORY"><code class="function">EXT:PROBE-DIRECTORY</code></a></h3></div></div></div><p><code class="code">(<a class="link" href="#probe-dir" title="20.3.1. Function EXT:PROBE-DIRECTORY"><code class="function">EXT:PROBE-DIRECTORY</code></a> <em class="replaceable"><code>pathname</code></em>)</code> tests whether <em class="replaceable"><code>pathname</code></em> exists
 and is a directory.
 It will, unlike <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_probe-file.html" target="_top"><code class="function">PROBE-FILE</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_truename.html" target="_top"><code class="function">TRUENAME</code></a>, not <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a> an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>
 if the parent directory of <em class="replaceable"><code>pathname</code></em> does not exist.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="directory"></a>20.3.2. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_directory.html" target="_top"><code class="function">DIRECTORY</code></a></h3></div></div></div><p><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_directory.html" target="_top"><code class="function">DIRECTORY</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>pathname</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
  :FULL :CIRCLE <code class="constant">:IF-DOES-NOT-EXIST</code>)</code> can run in two modes:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">If <em class="replaceable"><code>pathname</code></em> contains no name or type component, a
  list of all matching directories is produced.
  E.g., <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_directory.html" target="_top"><code class="function">DIRECTORY</code></a> "/etc/*/")</code> lists
  all subdirectories in the directory
  <code class="filename">#P"/etc/"</code>.</li><li class="listitem">Otherwise a list of all matching files is returned.
  E.g., <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_directory.html" target="_top"><code class="function">DIRECTORY</code></a> "/etc/*")</code> lists all
  regular files in the directory <code class="filename">#P"/etc/"</code>.
</li></ul></div><p>

If you want <span class="strong"><strong>all</strong></span> the files <span class="strong"><strong>and</strong></span> subdirectories in the current directory,
 you should use <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_nconc.html" target="_top"><code class="function">NCONC</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_directory.html" target="_top"><code class="function">DIRECTORY</code></a> "*/") (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_directory.html" target="_top"><code class="function">DIRECTORY</code></a> "*"))</code>.
If you want all the files and subdirectories in all the subdirectories
under the current directory (similar to the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/ls.html"><span class="command"><strong>ls
 <code class="option">-R</code></strong></span></a> <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> command), use
<code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_nconc.html" target="_top"><code class="function">NCONC</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_directory.html" target="_top"><code class="function">DIRECTORY</code></a> "**/") (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_directory.html" target="_top"><code class="function">DIRECTORY</code></a> "**/*"))</code>.</p><div class="variablelist"><p class="title"><strong>Keyword arguments accepted by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_directory.html" target="_top"><code class="function">DIRECTORY</code></a></strong></p><dl class="variablelist"><dt><span class="term"><code class="constant">:FULL</code></span></dt><dd>If this argument is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, additional
  information is returned: for each matching file you get a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of
  at least four elements <span class="returnvalue">(<em class="replaceable"><code>file-pathname</code></em>
    <em class="replaceable"><code>file-truename</code></em>
    <em class="replaceable"><code>file-write-date-as-decoded-time</code></em>
    <em class="replaceable"><code>file-length</code></em>)</span>.
</dd><dt><span class="term"><code class="constant">:CIRCLE</code></span></dt><dd>If this argument is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_directory.html" target="_top"><code class="function">DIRECTORY</code></a> avoids
 endless loops that may result from symbolic links.
</dd><dt><span class="term"><code class="constant">:IF-DOES-NOT-EXIST</code></span></dt><dd><p>This argument controls the treatment of links
  pointing to non-existent files and can take the following values:
  </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:DISCARD</code> (default)</span></dt><dd>discard the bad directory entries
   </dd><dt><span class="term"><code class="constant">:ERROR</code></span></dt><dd>an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed on bad directory entries
      (this corresponds to the default behavior of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_directory.html" target="_top"><code class="function">DIRECTORY</code></a> in <a class="ulink" href="http://www.cons.org/cmucl/" target="_top"><span class="command"><strong>CMU CL</strong></span></a>)
   </dd><dt><span class="term"><code class="constant">:KEEP</code></span></dt><dd>keep bad directory entries in the returned list
      (this roughly corresponds to the <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_directory.html" target="_top"><code class="function">DIRECTORY</code></a>
       ... <code class="constant">:TRUNAMEP</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>)</code> call in <a class="ulink" href="http://www.cons.org/cmucl/" target="_top"><span class="command"><strong>CMU CL</strong></span></a>)
   </dd><dt><span class="term"><code class="constant">:IGNORE</code></span></dt><dd>Similar to <code class="constant">:DISCARD</code>, but also do
      <span class="strong"><strong>not</strong></span> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a> an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> when a directory is unaccessible (contrary
      to the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] specification).</dd></dl></div></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="dir"></a>20.3.3. Function <code class="function">EXT:DIR</code></h3></div></div></div><p><code class="code">(<code class="function">EXT:DIR</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
 <em class="replaceable"><code>pathname</code></em>)</code> is like <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_directory.html" target="_top"><code class="function">DIRECTORY</code></a>, but displays the pathnames
 instead of returning them. <code class="code">(EXT:DIR)</code>
 shows the contents of the current directory.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="cd"></a>20.3.4. Function <a class="link" href="#cd" title="20.3.4. Function EXT:CD"><code class="function">EXT:CD</code></a></h3></div></div></div><p><code class="code">(<a class="link" href="#cd" title="20.3.4. Function EXT:CD"><code class="function">EXT:CD</code></a> <em class="replaceable"><code>pathname</code></em>)</code> sets the current working directory,
 <code class="code">(<a class="link" href="#cd" title="20.3.4. Function EXT:CD"><code class="function">EXT:CD</code></a>)</code> returns it.
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> platform only.</span></span></span></dt><dd><code class="code">(<a class="link" href="#cd" title="20.3.4. Function EXT:CD"><code class="function">EXT:CD</code></a> [<em class="replaceable"><code>pathname</code></em>])</code>
   manages the current directory.</dd><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platform only.</span></span></span></dt><dd><code class="code">(<a class="link" href="#cd" title="20.3.4. Function EXT:CD"><code class="function">EXT:CD</code></a> [<em class="replaceable"><code>pathname</code></em>])</code>
   manages the current device and the current directory.
   </dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="default-dir"></a>20.3.5. Function <a class="link" href="#default-dir" title="20.3.5. Function EXT:DEFAULT-DIRECTORY"><code class="function">EXT:DEFAULT-DIRECTORY</code></a></h3></div></div></div><p><code class="code">(<a class="link" href="#default-dir" title="20.3.5. Function EXT:DEFAULT-DIRECTORY"><code class="function">EXT:DEFAULT-DIRECTORY</code></a>)</code> is equivalent to <code class="code">(<a class="link" href="#cd" title="20.3.4. Function EXT:CD"><code class="function">EXT:CD</code></a>)</code>.
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="link" href="#default-dir" title="20.3.5. Function EXT:DEFAULT-DIRECTORY"><code class="function">EXT:DEFAULT-DIRECTORY</code></a>) <em class="replaceable"><code>pathname</code></em>)</code> is equivalent to
 <code class="code">(<a class="link" href="#cd" title="20.3.4. Function EXT:CD"><code class="function">EXT:CD</code></a> <em class="replaceable"><code>pathname</code></em>)</code>, except for the return value.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="make-dir"></a>20.3.6. Function <code class="function">EXT:MAKE-DIRECTORY</code></h3></div></div></div><p><code class="code">(<code class="function">EXT:MAKE-DIRECTORY</code> <em class="replaceable"><code>directory</code></em>)</code>
 creates a new subdirectory.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="delete-dir"></a>20.3.7. Function <a class="link" href="#delete-dir" title="20.3.7. Function EXT:DELETE-DIRECTORY"><code class="function">EXT:DELETE-DIRECTORY</code></a></h3></div></div></div><p><code class="code">(<a class="link" href="#delete-dir" title="20.3.7. Function EXT:DELETE-DIRECTORY"><code class="function">EXT:DELETE-DIRECTORY</code></a> <em class="replaceable"><code>directory</code></em>)</code>
 removes an (empty) subdirectory.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="rename-dir"></a>20.3.8. Function <a class="link" href="#rename-dir" title="20.3.8. Function EXT:RENAME-DIRECTORY"><code class="function">EXT:RENAME-DIRECTORY</code></a></h3></div></div></div><p><code class="code">(<a class="link" href="#rename-dir" title="20.3.8. Function EXT:RENAME-DIRECTORY"><code class="function">EXT:RENAME-DIRECTORY</code></a> <em class="replaceable"><code>old-directory</code></em>
  <em class="replaceable"><code>new-directory</code></em>)</code> renames a
 subdirectory to a new name.</p></div></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="streams"></a>Chapter 21. Streams <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-21.html">[chap-21]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#streams-interactive">21.1. Interactive Streams  sec_21-1-1-1-3</a></span></dt><dd><dl><dt><span class="section"><a href="#stream-stdio-init">21.1.1. Initialization of Standard Streams</a></span></dt></dl></dd><dt><span class="section"><a href="#terminal">21.2. Terminal interaction</a></span></dt><dd><dl><dt><span class="section"><a href="#readline">21.2.1. Command line editing with GNU readline</a></span></dt><dt><span class="section"><a href="#with-kbd">21.2.2. Macro <code class="function">EXT:WITH-KEYBOARD</code></a></span></dt></dl></dd><dt><span class="section"><a href="#bin-io">21.3. Binary Input and Output</a></span></dt><dd><dl><dt><span class="section"><a href="#bin-input">21.3.1. Binary input, <code class="function">READ-BYTE</code>,   <code class="function">EXT:READ-INTEGER</code> &amp; <code class="function">EXT:READ-FLOAT</code></a></span></dt><dt><span class="section"><a href="#bin-output">21.3.2. Binary output, <code class="function">WRITE-BYTE</code>,   <code class="function">EXT:WRITE-INTEGER</code> &amp; <code class="function">EXT:WRITE-FLOAT</code></a></span></dt></dl></dd><dt><span class="section"><a href="#bulk-io">21.4. Bulk Input and Output</a></span></dt><dd><dl><dt><span class="section"><a href="#read-seq">21.4.1. Bulk Input</a></span></dt><dt><span class="section"><a href="#write-seq">21.4.2. Bulk Output</a></span></dt><dt><span class="section"><a href="#bulk-io-rationale">21.4.3. Rationale</a></span></dt></dl></dd><dt><span class="section"><a href="#non-block-io">21.5. Non-Blocking Input and Output</a></span></dt><dt><span class="section"><a href="#newline-convention">21.6. Newline Convention</a></span></dt><dd><dl><dt><span class="section"><a href="#nl-question">21.6.1. Should programs output a newline before   or after each line of output?</a></span></dt><dt><span class="section"><a href="#nl-trad-analysis">21.6.2. Analysis</a></span></dt><dt><span class="section"><a href="#nl-conclusion">21.6.3. Conclusion</a></span></dt><dt><span class="section"><a href="#nl-solution">21.6.4. Solution</a></span></dt><dt><span class="section"><a href="#nl-elnl-analysis">21.6.5. Elastic Newline Analysis</a></span></dt></dl></dd><dt><span class="section"><a href="#stream-extfmt">21.7. Function <code class="function">STREAM-EXTERNAL-FORMAT</code></a></span></dt><dt><span class="section"><a href="#stream-eltype">21.8. Function <code class="function">STREAM-ELEMENT-TYPE</code></a></span></dt><dd><dl><dt><span class="section"><a href="#bin-stdio">21.8.1. Binary input from <code class="varname">*STANDARD-INPUT*</code></a></span></dt></dl></dd><dt><span class="section"><a href="#make-stream">21.9. Function <code class="function">EXT:MAKE-STREAM</code></a></span></dt><dt><span class="section"><a href="#file-pos">21.10. Function <code class="function">FILE-POSITION</code></a></span></dt><dt><span class="section"><a href="#elastic-newline">21.11. Function <code class="function">EXT:ELASTIC-NEWLINE</code></a></span></dt><dt><span class="section"><a href="#open">21.12. Function <code class="function">OPEN</code></a></span></dt><dt><span class="section"><a href="#clear-input">21.13. Function <code class="function">CLEAR-INPUT</code></a></span></dt><dt><span class="section"><a href="#close">21.14. Function <code class="function">CLOSE</code></a></span></dt><dt><span class="section"><a href="#open-stream-p">21.15. Function <code class="function">OPEN-STREAM-P</code></a></span></dt><dt><span class="section"><a href="#broadcast-stream">21.16. Class <code class="classname">BROADCAST-STREAM</code></a></span></dt><dt><span class="section"><a href="#stream-buffer">21.17. Functions   <code class="function">EXT:MAKE-BUFFERED-INPUT-STREAM</code>
    and   <code class="function">EXT:MAKE-BUFFERED-OUTPUT-STREAM</code>
     </a></span></dt><dt><span class="section"><a href="#stream-handles">21.18. Function   <code class="function">EXT:STREAM-HANDLES</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="streams-interactive"></a>21.1. Interactive Streams
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_21-1-1-1-3.html">[sec_21-1-1-1-3]</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#stream-stdio-init">21.1.1. Initialization of Standard Streams</a></span></dt></dl></div><p>Interactive streams are those whose next input might depend on a
 prompt one might output.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="stream-stdio-init"></a>21.1.1. Initialization of Standard Streams</h3></div></div></div><p>When run interactively, <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> creates a single <span class="quote">“<span class="quote">terminal</span>”</span>
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> and binds <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stterminal-iost.html" target="_top"><code class="varname">*TERMINAL-IO*</code></a> to it.
 All other standard streams (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-INPUT*</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-OUTPUT*</code></a>
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*ERROR-OUTPUT*</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*TRACE-OUTPUT*</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*QUERY-IO*</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*DEBUG-IO*</code></a>)
 are <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_synonym-stream.html" target="_top"><code class="classname">SYNONYM-STREAM</code></a>s pointing to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stterminal-iost.html" target="_top"><code class="varname">*TERMINAL-IO*</code></a>.
 This has the benefit of avoiding unwanted blank lines from <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_terpricm_fresh-line.html" target="_top"><code class="function">FRESH-LINE</code></a>,
 see <a class="xref" href="#newline-convention" title="21.6. Newline Convention">Section 21.6, “Newline Convention”</a>.</p><p>However, there may be situations, especially in <a href="clisp.html#batch-mode" class="olink">batch mode</a>,
 when one wants to use a <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>-style i/o where <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-OUTPUT*</code></a>
 and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*ERROR-OUTPUT*</code></a> point to different OS <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a> so that they can be
 <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_07">redirected</a>
 to files in the command line and examined separately.
 Often <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> can detect such situations (<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/stdout.html"><code class="varname">stdout</code></a> and <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/stderr.html"><code class="varname">stderr</code></a> not being
 the terminal) and handle them just as expected.
 However, there may be cases when one needs to do something like:
</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/spefor_setq.html" target="_top"><code class="function">SETQ</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-INPUT*</code></a> (<a class="link" href="#make-stream" title="21.9. Function EXT:MAKE-STREAM"><code class="function">EXT:MAKE-STREAM</code></a> <code class="constant">:INPUT</code>)
      <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-OUTPUT*</code></a> (<a class="link" href="#make-stream" title="21.9. Function EXT:MAKE-STREAM"><code class="function">EXT:MAKE-STREAM</code></a> <code class="constant">:OUTPUT</code> <a class="link" href="#buffered"><code class="constant">:BUFFERED</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>)
      <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*ERROR-OUTPUT*</code></a> (<a class="link" href="#make-stream" title="21.9. Function EXT:MAKE-STREAM"><code class="function">EXT:MAKE-STREAM</code></a> <code class="constant">:ERROR</code> <a class="link" href="#buffered"><code class="constant">:BUFFERED</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>))
</pre><p> in the <a href="clisp.html#opt-exec-file" class="olink">script</a> or <a href="impnotes.html#init-func" class="olink">init function</a>.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="terminal"></a>21.2. Terminal interaction</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#readline">21.2.1. Command line editing with GNU readline</a></span></dt><dt><span class="section"><a href="#with-kbd">21.2.2. Macro <code class="function">EXT:WITH-KEYBOARD</code></a></span></dt></dl></div><p>See also <a class="xref" href="#screen" title="32.1. Random Screen Access">Section 32.1, “Random Screen Access”</a>.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="readline"></a>21.2.1. Command line editing with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://tiswww.case.edu/php/chet/readline/readline.html" target="_top">readline</a></h3></div><div><h4 class="subtitle"><span class="plat-dep">Platform Dependent: <span class="plat-dep">Only in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> linked against the
   <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://tiswww.case.edu/php/chet/readline/readline.html" target="_top">readline</a> library.</span></span></h4></div></div></div><p>Input through <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stterminal-iost.html" target="_top"><code class="varname">*TERMINAL-IO*</code></a> uses the <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://tiswww.case.edu/php/chet/readline/readline.html" target="_top">readline</a> library.
  Arrow keys can be used to move within the input history.
  The <span class="keycode">TAB</span> key completes the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a> name or
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_pathname.html" target="_top"><code class="classname">PATHNAME</code></a> that is being typed.
  See <a class="ulink" href="http://tiswww.case.edu/php/chet/readline/rluserman.html" target="_top">readline user
  manual</a> for general details and
  <a href="clisp.html#completion" class="olink"><span class="keycode">TAB</span> key</a> for <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>-specific
  extensions.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>The <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://tiswww.case.edu/php/chet/readline/readline.html" target="_top">readline</a> library is <span class="strong"><strong>not</strong></span> used (even when
   <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> is linked against it) if the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/stdin.html"><code class="varname">stdin</code></a> and <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/stdout.html"><code class="varname">stdout</code></a> do not both
   refer to the same terminal.
   This is determined by the function <code class="function">stdio_same_tty_p</code>
   in file <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/stream.d"><code class="filename">src/stream.d</code></a>.
   In some exotic cases, e.g., when running under <a class="ulink" href="http://sources.redhat.com/gdb/" target="_top"><span class="command"><strong>gdb</strong></span></a> in
   an <span class="command"><strong>rxvt</strong></span> window under <a class="ulink" href="http://cygwin.com/" target="_top"><span class="platform">Cygwin</span></a>, this may be
   determined incorrectly.</p></div><p>See also <a class="xref" href="#readline-mod" title="33.5. Advanced Readline and History Functionality">Section 33.5, “Advanced Readline and History Functionality”</a>.</p><p><a id="readline-config"></a><strong>Linking against <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://tiswww.case.edu/php/chet/readline/readline.html" target="_top">readline</a>. </strong>For <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> to use <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://tiswww.case.edu/php/chet/readline/readline.html" target="_top">readline</a> it has to be detected by
  the <a class="ulink" href="http://www.gnu.org/software/autoconf/" target="_top"><span class="command"><strong>configure</strong></span></a> process.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>If you run it as
     </p><pre class="screen"><strong><code class="prompt">$</code></strong> ./configure --with-readline</pre><p>
     it will fail if it cannot find a valid modern <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://tiswww.case.edu/php/chet/readline/readline.html" target="_top">readline</a>
     installation.</p></li><li class="listitem">If you use the option
     <code class="option">--without-readline</code>, it will not even try to
     find <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://tiswww.case.edu/php/chet/readline/readline.html" target="_top">readline</a>.</li><li class="listitem">The default behavior
     (<code class="option">--with-readline=default</code>) is to use <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://tiswww.case.edu/php/chet/readline/readline.html" target="_top">readline</a> if
     it is found and link <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> without it otherwise.
  </li></ul></div><p>
  You can find out whether <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://tiswww.case.edu/php/chet/readline/readline.html" target="_top">readline</a> has been detected by running
  </p><pre class="screen"><strong><code class="prompt">$</code></strong> <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/grep.html"><span class="command"><strong>grep</strong></span></a> HAVE_READLINE config.h</pre><p>
  in your build directory.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="with-kbd"></a>21.2.2. Macro <a class="link" href="#with-kbd" title="21.2.2. Macro EXT:WITH-KEYBOARD"><code class="function">EXT:WITH-KEYBOARD</code></a></h3></div><div><h4 class="subtitle"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platforms only.</span></span></h4></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stterminal-iost.html" target="_top"><code class="varname">*TERMINAL-IO*</code></a> is not the only stream that
 communicates directly with the user: During execution of the body of a
 <code class="code">(<a class="link" href="#with-kbd" title="21.2.2. Macro EXT:WITH-KEYBOARD"><code class="function">EXT:WITH-KEYBOARD</code></a> . <em class="replaceable"><code>body</code></em>)</code> form,
 <strong class="first"><em class="firstterm"><a href="impnotes.html#with-kbd" class="olink"><code class="varname">EXT:*KEYBOARD-INPUT*</code></a></em></strong> is the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> that reads the
 keystrokes from the keyboard.
 It returns every keystroke in detail as an <a class="link" href="#input-char" title="13.4.1. Input Characters"><code class="classname">SYS::INPUT-CHARACTER</code></a> with the
 following slots (see <a class="xref" href="#input-char" title="13.4.1. Input Characters">Section 13.4.1, “Input Characters”</a> for accessing them):
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>char</code></em></span></dt><dd><p class="simpara">the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a> for standard keys
    (accessed with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_character.html" target="_top"><code class="function">CHARACTER</code></a>)</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>For non-standard keys <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_character.html" target="_top"><code class="function">CHARACTER</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>, use <a class="link" href="#with-kbd" title="21.2.2. Macro EXT:WITH-KEYBOARD"><code class="function">EXT:CHAR-KEY</code></a>:
</p><pre class="programlisting">
(<a class="link" href="#with-kbd" title="21.2.2. Macro EXT:WITH-KEYBOARD"><code class="function">EXT:WITH-KEYBOARD</code></a>
 (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_loop.html" target="_top"><code class="function">LOOP</code></a> :for <em class="replaceable"><code>char</code></em> = (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-char.html" target="_top"><code class="function">READ-CHAR</code></a> <a href="impnotes.html#with-kbd" class="olink"><code class="varname">EXT:*KEYBOARD-INPUT*</code></a>)
   :for <em class="replaceable"><code>key</code></em> = (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_or.html" target="_top"><code class="function">OR</code></a> (<a class="link" href="#with-kbd" title="21.2.2. Macro EXT:WITH-KEYBOARD"><code class="function">EXT:CHAR-KEY</code></a> <em class="replaceable"><code>char</code></em>) (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_character.html" target="_top"><code class="function">CHARACTER</code></a> <em class="replaceable"><code>char</code></em>))
   :do (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">PRINT</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_listcm_listst.html" target="_top"><code class="function">LIST</code></a> <em class="replaceable"><code>char</code></em> <em class="replaceable"><code>key</code></em>))
   :when (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eql.html" target="_top"><code class="function">EQL</code></a> <em class="replaceable"><code>key</code></em> #\Space) :return (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_listcm_listst.html" target="_top"><code class="function">LIST</code></a> <em class="replaceable"><code>char</code></em> <em class="replaceable"><code>key</code></em>)))
</pre></div></dd><dt><span class="term"><em class="replaceable"><code>key</code></em></span></dt><dd><p>the key name, for non-standard keys
    (accessed with <a class="link" href="#with-kbd" title="21.2.2. Macro EXT:WITH-KEYBOARD"><code class="function">EXT:CHAR-KEY</code></a>):
    </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platforms only.</span></span></span></dt><dd><div class="informaltable"><a id="unix-kbd-keys"></a><table class="informaltable" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="center">key</th><th align="center">value</th></tr></thead><tbody><tr><td align="center"><span class="keycode">F1</span>..<span class="keycode">F12</span></td><td align="center"><code class="constant">:F1</code>..<code class="constant">:F12</code>
          </td></tr><tr><td align="center"><span class="keycode">Insert</span></td><td align="center"><code class="constant">:INSERT</code></td></tr><tr><td align="center"><span class="keycode">Delete</span></td><td align="center"><code class="constant">:DELETE</code></td></tr><tr><td align="center"><span class="keycode">Home</span></td><td align="center"><code class="constant">:HOME</code></td></tr><tr><td align="center"><span class="keycode">End</span></td><td align="center"><code class="constant">:END</code></td></tr><tr><td align="center"><span class="keycode">Center</span></td><td align="center"><code class="constant">:CENTER</code></td></tr><tr><td align="center"><span class="keycode">PgUp</span></td><td align="center"><code class="constant">:PGUP</code></td></tr><tr><td align="center"><span class="keycode">PgDn</span></td><td align="center"><code class="constant">:PGDN</code></td></tr><tr><td align="center">Arrow keys</td><td align="center"><code class="constant">:LEFT</code> <code class="constant">:RIGHT</code>
            <code class="constant">:UP</code> <code class="constant">:DOWN</code></td></tr></tbody></table></div></dd></dl></div></dd><dt><span class="term"><em class="replaceable"><code>bits</code></em></span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:HYPER</code></span></dt><dd>(<span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platform only.</span></span>) if a non-standard key.
        These keys are:
        
        <span class="emphasis"><em>[<a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>]:</em></span>
        Function keys, cursor keypads, numeric keypad.
        
     </dd><dt><span class="term"><code class="constant">:SUPER</code></span></dt><dd>(<span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platform only.</span></span>) if pressed together with <span class="keycap"><strong>Shift</strong></span>
        key(s) and if the keystroke would have been different without
        <span class="keycap"><strong>Shift</strong></span>.</dd><dt><span class="term"><code class="constant">:CONTROL</code></span></dt><dd>if pressed together with the <span class="keycap"><strong>Control</strong></span> key.
     </dd><dt><span class="term"><code class="constant">:META</code></span></dt><dd>(<span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platform only.</span></span>) if pressed together with the
        <span class="keycap"><strong>Alternate</strong></span> key.</dd></dl></div></dd><dt><span class="term"><em class="replaceable"><code>font</code></em></span></dt><dd>Always <code class="literal">0</code>.</dd></dl></div><p>
This keyboard input is not echoed on the screen.  During execution of a
<code class="code">(<a class="link" href="#with-kbd" title="21.2.2. Macro EXT:WITH-KEYBOARD"><code class="function">EXT:WITH-KEYBOARD</code></a> . <em class="replaceable"><code>body</code></em>)</code> form, no input from
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stterminal-iost.html" target="_top"><code class="varname">*TERMINAL-IO*</code></a> or any synonymous stream should be requested.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>Since <a class="link" href="#input-char" title="13.4.1. Input Characters"><code class="classname">SYS::INPUT-CHARACTER</code></a> is <span class="strong"><strong>not</strong></span> a subtype of
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-line.html" target="_top"><code class="function">READ-LINE</code></a> on <a href="impnotes.html#with-kbd" class="olink"><code class="varname">EXT:*KEYBOARD-INPUT*</code></a> is illegal.</p></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="bin-io"></a>21.3. Binary Input and Output</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#bin-input">21.3.1. Binary input, <code class="function">READ-BYTE</code>,   <code class="function">EXT:READ-INTEGER</code> &amp; <code class="function">EXT:READ-FLOAT</code></a></span></dt><dt><span class="section"><a href="#bin-output">21.3.2. Binary output, <code class="function">WRITE-BYTE</code>,   <code class="function">EXT:WRITE-INTEGER</code> &amp; <code class="function">EXT:WRITE-FLOAT</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="bin-input"></a>21.3.1. Binary input, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-byte.html" target="_top"><code class="function">READ-BYTE</code></a>,
  <a class="link" href="#bin-input" title="21.3.1. Binary input, READ-BYTE, EXT:READ-INTEGER &amp; EXT:READ-FLOAT"><code class="function">EXT:READ-INTEGER</code></a> &amp; <a class="link" href="#bin-input" title="21.3.1. Binary input, READ-BYTE, EXT:READ-INTEGER &amp; EXT:READ-FLOAT"><code class="function">EXT:READ-FLOAT</code></a></h3></div></div></div><p>The function <code class="code">(<a class="link" href="#bin-input" title="21.3.1. Binary input, READ-BYTE, EXT:READ-INTEGER &amp; EXT:READ-FLOAT"><code class="function">EXT:READ-INTEGER</code></a> <em class="replaceable"><code>stream</code></em>
    <em class="replaceable"><code>element-type</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <a class="link" href="#endianness" title="Endianness"><em class="replaceable"><code>ENDIANNESS</code></em></a> <em class="replaceable"><code>eof-error-p</code></em> <em class="replaceable"><code>eof-value</code></em>)</code>
 reads a multi-byte <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> from <em class="replaceable"><code>stream</code></em>, which should be a
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span>.
 <em class="replaceable"><code>element-type</code></em> should be <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_t.html#type_equivalent">type equivalent</a> to <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> <em class="replaceable"><code>n</code></em>)</code></span>,
 where <em class="replaceable"><code>n</code></em> is a multiple of 8.</p><p><code class="code">(<a class="link" href="#bin-input" title="21.3.1. Binary input, READ-BYTE, EXT:READ-INTEGER &amp; EXT:READ-FLOAT"><code class="function">EXT:READ-INTEGER</code></a> <em class="replaceable"><code>stream</code></em> <em class="replaceable"><code>element-type</code></em>)</code> is like
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-byte.html" target="_top"><code class="function">READ-BYTE</code></a> <em class="replaceable"><code>stream</code></em>)</code> if <em class="replaceable"><code>stream</code></em>'s
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> were set to <em class="replaceable"><code>element-type</code></em>,
 except that <em class="replaceable"><code>stream</code></em>'s <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_file-position.html" target="_top"><code class="function">FILE-POSITION</code></a> will increase by
 <sup><em class="replaceable"><code>n</code></em></sup>/<sub>8</sub>
 instead of 1.</p><p>Together with <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a>)</code>, this
 function permits mixed character/binary input from a stream.</p><p>The function <code class="code">(<a class="link" href="#bin-input" title="21.3.1. Binary input, READ-BYTE, EXT:READ-INTEGER &amp; EXT:READ-FLOAT"><code class="function">EXT:READ-FLOAT</code></a> <em class="replaceable"><code>stream</code></em> <em class="replaceable"><code>element-type</code></em>
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <a class="link" href="#endianness" title="Endianness"><em class="replaceable"><code>ENDIANNESS</code></em></a> <em class="replaceable"><code>eof-error-p</code></em> <em class="replaceable"><code>eof-value</code></em>)</code> reads a
 floating-point number in <a class="ulink" href="http://grouper.ieee.org/groups/754/" target="_top">IEEE 754</a> binary representation from
 <em class="replaceable"><code>stream</code></em>, which should be a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> with
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span>.  <em class="replaceable"><code>element-type</code></em> should be
 <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_t.html#type_equivalent">type equivalent</a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SINGLE-FLOAT</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">DOUBLE-FLOAT</code></a>.</p><p><a id="endianness"></a><strong>Endianness. </strong><strong class="first"><em class="firstterm"><a class="link" href="#endianness" title="Endianness"><em class="replaceable"><code>ENDIANNESS</code></em></a>
   <a id="endianness-i" class="indexterm"></a></em></strong>
  can be <code class="constant">:LITTLE</code> or <code class="constant">:BIG</code>.
  The default is <code class="constant">:LITTLE</code>, which corresponds
  to the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-byte.html" target="_top"><code class="function">READ-BYTE</code></a> behavior in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="bin-output"></a>21.3.2. Binary output, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_write-byte.html" target="_top"><code class="function">WRITE-BYTE</code></a>,
  <a class="link" href="#bin-output" title="21.3.2. Binary output, WRITE-BYTE, EXT:WRITE-INTEGER &amp; EXT:WRITE-FLOAT"><code class="function">EXT:WRITE-INTEGER</code></a> &amp; <a class="link" href="#bin-output" title="21.3.2. Binary output, WRITE-BYTE, EXT:WRITE-INTEGER &amp; EXT:WRITE-FLOAT"><code class="function">EXT:WRITE-FLOAT</code></a></h3></div></div></div><p>The function <code class="code">(<a class="link" href="#bin-output" title="21.3.2. Binary output, WRITE-BYTE, EXT:WRITE-INTEGER &amp; EXT:WRITE-FLOAT"><code class="function">EXT:WRITE-INTEGER</code></a> <em class="replaceable"><code>integer</code></em> <em class="replaceable"><code>stream</code></em> <em class="replaceable"><code>element-type</code></em>
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <a class="link" href="#endianness" title="Endianness"><em class="replaceable"><code>ENDIANNESS</code></em></a>)</code> writes a multi-byte <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> to
 <em class="replaceable"><code>stream</code></em>, which should be a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> with
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span>.  <em class="replaceable"><code>element-type</code></em> should be
 <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_t.html#type_equivalent">type equivalent</a> to <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> <em class="replaceable"><code>n</code></em>)</code></span>, where <em class="replaceable"><code>n</code></em> is a multiple of 8.</p><p><code class="code">(<a class="link" href="#bin-output" title="21.3.2. Binary output, WRITE-BYTE, EXT:WRITE-INTEGER &amp; EXT:WRITE-FLOAT"><code class="function">EXT:WRITE-INTEGER</code></a> <em class="replaceable"><code>integer</code></em> <em class="replaceable"><code>stream</code></em> <em class="replaceable"><code>element-type</code></em>)</code> is
 like <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_write-byte.html" target="_top"><code class="function">WRITE-BYTE</code></a> <em class="replaceable"><code>integer</code></em> <em class="replaceable"><code>stream</code></em>)</code> if <em class="replaceable"><code>stream</code></em>'s
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> were set to <em class="replaceable"><code>element-type</code></em>, except that <em class="replaceable"><code>stream</code></em>'s
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_file-position.html" target="_top"><code class="function">FILE-POSITION</code></a> will increase by
 <sup><em class="replaceable"><code>n</code></em></sup>/<sub>8</sub>
 instead of 1.</p><p>Together with <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a>)</code>, this
  function permits mixed character/binary output to a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>.</p><p>The function <code class="code">(<a class="link" href="#bin-output" title="21.3.2. Binary output, WRITE-BYTE, EXT:WRITE-INTEGER &amp; EXT:WRITE-FLOAT"><code class="function">EXT:WRITE-FLOAT</code></a> <em class="replaceable"><code>float</code></em>
  <em class="replaceable"><code>stream</code></em> <em class="replaceable"><code>element-type</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <a class="link" href="#endianness" title="Endianness"><em class="replaceable"><code>ENDIANNESS</code></em></a>)</code> writes a
 floating-point number in <a class="ulink" href="http://grouper.ieee.org/groups/754/" target="_top">IEEE 754</a> binary representation to
 <em class="replaceable"><code>stream</code></em>, which should be a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a>
 <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span>.  <em class="replaceable"><code>element-type</code></em> should be
 <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_t.html#type_equivalent">type equivalent</a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SINGLE-FLOAT</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">DOUBLE-FLOAT</code></a>.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="bulk-io"></a>21.4. Bulk Input and Output</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#read-seq">21.4.1. Bulk Input</a></span></dt><dt><span class="section"><a href="#write-seq">21.4.2. Bulk Output</a></span></dt><dt><span class="section"><a href="#bulk-io-rationale">21.4.3. Rationale</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="read-seq"></a>21.4.1. Bulk Input</h3></div></div></div><p>In addition to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-sequence.html" target="_top"><code class="function">READ-SEQUENCE</code></a>, the following two functions are provided:
</p><div class="variablelist"><dl class="variablelist"><dt><a id="rd-by-seq"></a><span class="term"><a class="link" href="#rd-by-seq"><code class="function">EXT:READ-BYTE-SEQUENCE</code></a>
   performs multiple <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-byte.html" target="_top"><code class="function">READ-BYTE</code></a> operations:</span></dt><dd><p class="simpara"><code class="code">(<a class="link" href="#rd-by-seq"><code class="function">EXT:READ-BYTE-SEQUENCE</code></a> <em class="replaceable"><code>sequence</code></em>
   <em class="replaceable"><code>stream</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:START</code> <code class="constant">:END</code> :NO-HANG :INTERACTIVE)</code>
   fills the subsequence of <em class="replaceable"><code>sequence</code></em> specified by <code class="constant">:START</code> and <code class="constant">:END</code>
   with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>s consecutively read from <em class="replaceable"><code>stream</code></em>.  It returns the
   index of the first element of <em class="replaceable"><code>sequence</code></em> that was not updated (=
   <em class="replaceable"><code>end</code></em> or &lt; <em class="replaceable"><code>end</code></em> if the <em class="replaceable"><code>stream</code></em> reached its end).
   When <em class="replaceable"><code>no-hang</code></em> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, it does not block: it treats input
   unavailability as <code class="literal"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#end-of-stream">end-of-stream</a></code>. When <em class="replaceable"><code>no-hang</code></em> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and <em class="replaceable"><code>interactive</code></em> is
   non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, it can block for reading the first byte but does not block
   for any further bytes.</p><p class="simpara">This function is especially efficient if <em class="replaceable"><code>sequence</code></em> is a
   <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8))</code></span> and <em class="replaceable"><code>stream</code></em> is a <a class="link" href="#open" title="21.12. Function OPEN">file</a>/<a class="link" href="#pipe" title="32.7.2. Pipes">pipe</a>/<a class="link" href="#socket" title="32.4. Socket Streams">socket</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>
   with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span>.
 </p></dd><dt><a id="rd-ch-seq"></a><span class="term"><a class="link" href="#rd-ch-seq"><code class="function">EXT:READ-CHAR-SEQUENCE</code></a>
   performs multiple <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-char.html" target="_top"><code class="function">READ-CHAR</code></a> operations:</span></dt><dd><p class="simpara"><code class="code">(<a class="link" href="#rd-ch-seq"><code class="function">EXT:READ-CHAR-SEQUENCE</code></a> <em class="replaceable"><code>sequence</code></em> <em class="replaceable"><code>stream</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    <code class="constant">:START</code> <code class="constant">:END</code>)</code> fills the subsequence of <em class="replaceable"><code>sequence</code></em>
   specified by <code class="constant">:START</code> and <code class="constant">:END</code> with characters consecutively read
   from <em class="replaceable"><code>stream</code></em>.  It returns the index of the first element of
   <em class="replaceable"><code>sequence</code></em> that was not updated (= <em class="replaceable"><code>end</code></em> or &lt; <em class="replaceable"><code>end</code></em> if the
   <em class="replaceable"><code>stream</code></em> reached its end).</p><p class="simpara">This function is especially efficient if <em class="replaceable"><code>sequence</code></em> is a
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> and <em class="replaceable"><code>stream</code></em> is a <a class="link" href="#open" title="21.12. Function OPEN">file</a>/<a class="link" href="#pipe" title="32.7.2. Pipes">pipe</a>/<a class="link" href="#socket" title="32.4. Socket Streams">socket</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> with
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a> or an <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_i.html#input">input</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string-stream.html" target="_top"><code class="classname">STRING-STREAM</code></a>.
 </p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="write-seq"></a>21.4.2. Bulk Output</h3></div></div></div><p>In addition to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_write-sequence.html" target="_top"><code class="function">WRITE-SEQUENCE</code></a>, the following two functions are provided:
</p><div class="variablelist"><dl class="variablelist"><dt><a id="wr-by-seq"></a><span class="term"><a class="link" href="#wr-by-seq"><code class="function">EXT:WRITE-BYTE-SEQUENCE</code></a>
   performs multiple <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_write-byte.html" target="_top"><code class="function">WRITE-BYTE</code></a> operations:</span></dt><dd><p class="simpara"><code class="code">(<a class="link" href="#wr-by-seq"><code class="function">EXT:WRITE-BYTE-SEQUENCE</code></a> <em class="replaceable"><code>sequence</code></em> <em class="replaceable"><code>stream</code></em>
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:START</code> <code class="constant">:END</code> :NO-HANG :INTERACTIVE)</code> outputs
  the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>s of the subsequence of <em class="replaceable"><code>sequence</code></em> specified by
  <code class="constant">:START</code> and <code class="constant">:END</code> to <em class="replaceable"><code>stream</code></em>.
  When <em class="replaceable"><code>no-hang</code></em> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, does not block.
  When <em class="replaceable"><code>no-hang</code></em> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and <em class="replaceable"><code>interactive</code></em> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, it can
  block for writing the first byte but does not block for any further
  bytes.  Returns two values: <em class="replaceable"><code>sequence</code></em> and the index of the first
  byte that was not output.</p><p class="simpara">This function is especially efficient if <em class="replaceable"><code>sequence</code></em> is a
  <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8))</code></span> and <em class="replaceable"><code>stream</code></em> is a <a class="link" href="#open" title="21.12. Function OPEN">file</a>/<a class="link" href="#pipe" title="32.7.2. Pipes">pipe</a>/<a class="link" href="#socket" title="32.4. Socket Streams">socket</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> with
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span>.</p></dd><dt><a id="wr-ch-seq"></a><span class="term"><a class="link" href="#wr-ch-seq"><code class="function">EXT:WRITE-CHAR-SEQUENCE</code></a>
  performs multiple <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_write-char.html" target="_top"><code class="function">WRITE-CHAR</code></a> operations:</span></dt><dd><p class="simpara"><code class="code">(<a class="link" href="#wr-ch-seq"><code class="function">EXT:WRITE-CHAR-SEQUENCE</code></a> <em class="replaceable"><code>sequence</code></em> <em class="replaceable"><code>stream</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
  <code class="constant">:START</code> <code class="constant">:END</code>)</code> outputs the characters of the subsequence of
  <em class="replaceable"><code>sequence</code></em> specified by <code class="constant">:START</code> and <code class="constant">:END</code> to <em class="replaceable"><code>stream</code></em>.
  Returns the <em class="replaceable"><code>sequence</code></em> argument.</p><p class="simpara">This function is especially efficient if <em class="replaceable"><code>sequence</code></em> is a
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> and <em class="replaceable"><code>stream</code></em> is a <a class="link" href="#open" title="21.12. Function OPEN">file</a>/<a class="link" href="#pipe" title="32.7.2. Pipes">pipe</a>/<a class="link" href="#socket" title="32.4. Socket Streams">socket</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> with
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>.</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="bulk-io-rationale"></a>21.4.3. Rationale</h3></div></div></div><p>The rationale for <a class="link" href="#rd-ch-seq"><code class="function">EXT:READ-CHAR-SEQUENCE</code></a>, <a class="link" href="#rd-by-seq"><code class="function">EXT:READ-BYTE-SEQUENCE</code></a>, <a class="link" href="#wr-ch-seq"><code class="function">EXT:WRITE-CHAR-SEQUENCE</code></a> and
 <a class="link" href="#wr-by-seq"><code class="function">EXT:WRITE-BYTE-SEQUENCE</code></a> is that some <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s support both character and binary
 i/o, and when you read into a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_sequence.html" target="_top"><code class="classname">SEQUENCE</code></a> that can hold both (e.g.,
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-vector.html" target="_top"><code class="classname">SIMPLE-VECTOR</code></a>) you cannot determine which kind of
 input to use.  In such situation <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-sequence.html" target="_top"><code class="function">READ-SEQUENCE</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_write-sequence.html" target="_top"><code class="function">WRITE-SEQUENCE</code></a>
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a> an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>, while <a class="link" href="#rd-ch-seq"><code class="function">EXT:READ-CHAR-SEQUENCE</code></a>, <a class="link" href="#rd-by-seq"><code class="function">EXT:READ-BYTE-SEQUENCE</code></a>, <a class="link" href="#wr-ch-seq"><code class="function">EXT:WRITE-CHAR-SEQUENCE</code></a> and
 <a class="link" href="#wr-by-seq"><code class="function">EXT:WRITE-BYTE-SEQUENCE</code></a> work just fine.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="non-block-io"></a>21.5. Non-Blocking Input and Output</h2></div></div></div><p>In addition to the standard functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_listen.html" target="_top"><code class="function">LISTEN</code></a> and
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-char-no-hang.html" target="_top"><code class="function">READ-CHAR-NO-HANG</code></a>, <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> provides the following functionality
 facilitating non-blocking input and output, both binary and
 character.</p><div class="variablelist"><dl class="variablelist"><dt><a id="rcwhp"></a><span class="term"><code class="code">(<a class="link" href="#rcwhp"><code class="function">EXT:READ-CHAR-WILL-HANG-P</code></a> <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara"><a class="link" href="#rcwhp"><code class="function">EXT:READ-CHAR-WILL-HANG-P</code></a> queries the stream's input status.
  It returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-char.html" target="_top"><code class="function">READ-CHAR</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_peek-char.html" target="_top"><code class="function">PEEK-CHAR</code></a> with a
  <em class="replaceable"><code>peek-type</code></em> of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> will return immediately.
  Otherwise it returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.  (In the latter case the standard
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_listen.html" target="_top"><code class="function">LISTEN</code></a> function would return <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.)</p><p class="simpara">Note the difference with <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_not.html" target="_top"><code class="function">NOT</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_listen.html" target="_top"><code class="function">LISTEN</code></a>
  <em class="replaceable"><code>stream</code></em>))</code>: When the <code class="literal"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#end-of-stream">end-of-stream</a></code> is reached, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_listen.html" target="_top"><code class="function">LISTEN</code></a> returns
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, whereas <a class="link" href="#rcwhp"><code class="function">EXT:READ-CHAR-WILL-HANG-P</code></a> returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</p><p class="simpara">Note also that <a class="link" href="#rcwhp"><code class="function">EXT:READ-CHAR-WILL-HANG-P</code></a> is not a good way to test for <code class="literal"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#end-of-stream">end-of-stream</a></code>:
  If <a class="link" href="#rcwhp"><code class="function">EXT:READ-CHAR-WILL-HANG-P</code></a> returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>, this does not mean that the <em class="replaceable"><code>stream</code></em> will
  deliver more characters.  It only means that it is not known at this
  moment whether the <em class="replaceable"><code>stream</code></em> is already at <code class="literal"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#end-of-stream">end-of-stream</a></code>, or will deliver
  more characters.</p></dd><dt><a id="rbla"></a><span class="term"><code class="code">(<a class="link" href="#rbla"><code class="function">EXT:READ-BYTE-LOOKAHEAD</code></a> <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd>To be called only if <em class="replaceable"><code>stream</code></em>'s
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> is <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span> or <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_signed-byte.html" target="_top"><code class="classname">SIGNED-BYTE</code></a> 8)</code></span>.
   Returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> if <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-byte.html" target="_top"><code class="function">READ-BYTE</code></a> would return immediately with an
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> result.
   Returns <code class="constant">:EOF</code> if the <code class="literal"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#end-of-stream">end-of-stream</a></code> is already known to be reached.
   If <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-byte.html" target="_top"><code class="function">READ-BYTE</code></a>'s value is not available immediately, returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
   instead of waiting.</dd><dt><a id="rbwhp"></a><span class="term"><code class="code">(<a class="link" href="#rbwhp"><code class="function">EXT:READ-BYTE-WILL-HANG-P</code></a> <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd>To be called only if <em class="replaceable"><code>stream</code></em>'s
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> is <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span> or <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_signed-byte.html" target="_top"><code class="classname">SIGNED-BYTE</code></a> 8)</code></span>.
   Returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-byte.html" target="_top"><code class="function">READ-BYTE</code></a> will return immediately.
   Otherwise it returns true.</dd><dt><a id="rbnh"></a><span class="term"><code class="code">(<a class="link" href="#rbnh"><code class="function">EXT:READ-BYTE-NO-HANG</code></a> <em class="replaceable"><code>stream</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
    <em class="replaceable"><code>eof-error-p</code></em> <em class="replaceable"><code>eof-value</code></em>)</code></span></dt><dd>To be called only if <em class="replaceable"><code>stream</code></em>'s
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> is <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span> or <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_signed-byte.html" target="_top"><code class="classname">SIGNED-BYTE</code></a> 8)</code></span>.
   Returns an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> or does <code class="literal"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#end-of-stream">end-of-stream</a></code> handling, like <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-byte.html" target="_top"><code class="function">READ-BYTE</code></a>,
   if that would return immediately.
   If <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-byte.html" target="_top"><code class="function">READ-BYTE</code></a>'s value is not available immediately, returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
   instead of waiting.</dd></dl></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="listen-byte"></a><code class="function">LISTEN</code> on binary streams</h3><p>The [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] specification for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_listen.html" target="_top"><code class="function">LISTEN</code></a> mentions <span class="quote">“<span class="quote">character
   availability</span>”</span> as the criterion that determines the return value.
  Since a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a> is <span class="emphasis"><em>never</em></span> available on a
  binary <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> (i.e., a stream with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> being a
  subtype of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>), <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_listen.html" target="_top"><code class="function">LISTEN</code></a> returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> for such streams.
  (You can use <a class="link" href="#so-status"><code class="function">SOCKET:SOCKET-STATUS</code></a> to check binary streams).
  Any other behavior would be hard to make consistent: consider a bivalent
  stream, i.e., a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> that can be operated upon by both
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-char.html" target="_top"><code class="function">READ-CHAR</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-byte.html" target="_top"><code class="function">READ-BYTE</code></a>.
  What should <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_listen.html" target="_top"><code class="function">LISTEN</code></a> return on such a stream if what is actually available
  on the stream at the moment is only a part of a multi-byte character?
  Right now one can use first <a class="link" href="#so-status"><code class="function">SOCKET:SOCKET-STATUS</code></a> to check if anything at all is
  available and then use <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_listen.html" target="_top"><code class="function">LISTEN</code></a> to make sure that a full <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>
  is actually there.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="newline-convention"></a>21.6. Newline Convention</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#nl-question">21.6.1. Should programs output a newline before   or after each line of output?</a></span></dt><dt><span class="section"><a href="#nl-trad-analysis">21.6.2. Analysis</a></span></dt><dt><span class="section"><a href="#nl-conclusion">21.6.3. Conclusion</a></span></dt><dt><span class="section"><a href="#nl-solution">21.6.4. Solution</a></span></dt><dt><span class="section"><a href="#nl-elnl-analysis">21.6.5. Elastic Newline Analysis</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="nl-question"></a>21.6.1. Should programs output a newline before
  or after each line of output?</h3></div></div></div><p>The answer is complicated. There is an antagonism between
 the <span class="quote">“<span class="quote">old Lisp way</span>”</span> of outputting a newline before the
 line's contents (exemplified by the functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">PRINT</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">PPRINT</code></a>) and
 the <span class="quote">“<span class="quote">Unix way</span>”</span> of outputting a newline after the line's
 contents. Which one is <span class="quote">“<span class="quote">right</span>”</span>?</p><p>A newline convention is, by definition, a consistent way to use
 the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_terpricm_fresh-line.html" target="_top"><code class="function">TERPRI</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_terpricm_fresh-line.html" target="_top"><code class="function">FRESH-LINE</code></a> functions or - in <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> notation -
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-1-2.html"><code class="literal">~%</code></a> and <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-1-3.html"><code class="literal">~&amp;</code></a> directives in such a way that the
 resulting output is properly subdivided into lines.</p><p>Three newline conventions are conceivable:</p><div class="orderedlist"><ol class="orderedlist" type="A"><li class="listitem">Print a newline before the line, and nothing after it.
   As a format string: <span class="format"><span class="quote">“<span class="quote">~%First line.~%Second line.</span>”</span></span>
 </li><li class="listitem">Print a newline if needed before the line,
   and a newline always after it. As a format string:
   <span class="format"><span class="quote">“<span class="quote">~&amp;First line.~%Second line.~%</span>”</span></span>
 </li><li class="listitem">Print nothing before the line, and a newline always
   after it. As a format string:
   <span class="format"><span class="quote">“<span class="quote">First line.~%Second line.~%</span>”</span></span>
</li></ol></div><p>The most important criterion is interoperability.  Two newline
conventions are interoperable if, when parts of a program use one of the
convention and other parts of the program use the other conventions,
lines are still properly separated.  It is easily seen that <span class="strong"><strong>A</strong></span> and
<span class="strong"><strong>B</strong></span> are interoperable, <span class="strong"><strong>B</strong></span> and <span class="strong"><strong>C</strong></span> are interoperable as well,
but <span class="strong"><strong>A</strong></span> and <span class="strong"><strong>C</strong></span> are not interoperable: When an output with
convention <span class="strong"><strong>A</strong></span> is followed by output in convention <span class="strong"><strong>C</strong></span>, two lines
are appended without a line separator.  This should not happen.</p><p>Therefore, in what follows, we consider five kinds of programs:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="strong"><strong>A</strong></span>: using convention <span class="strong"><strong>A</strong></span> exclusively,
</li><li class="listitem"><span class="strong"><strong>AB</strong></span>: mixing conventions <span class="strong"><strong>A</strong></span> and <span class="strong"><strong>B</strong></span>,
</li><li class="listitem"><span class="strong"><strong>B</strong></span>: using convention <span class="strong"><strong>B</strong></span> exclusively,
</li><li class="listitem"><span class="strong"><strong>BC</strong></span>: mixing conventions <span class="strong"><strong>B</strong></span> and <span class="strong"><strong>C</strong></span>,
</li><li class="listitem"><span class="strong"><strong>C</strong></span>: using convention <span class="strong"><strong>C</strong></span> exclusively.
</li></ul></div><p>Which of these five kinds of programs operation is satisfactory?
Let us consider different criteria:</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">Do extra blank lines occur during normal operation?
 </li><li class="listitem">What happens if <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_terpricm_fresh-line.html" target="_top"><code class="function">FRESH-LINE</code></a> prints a newline when
   it is not needed, i.e. when it cannot tell for sure whether the
   current column is 0?  (This situation happens, for example, when
   logging to a file: After the user has entered a line interactively,
   the column on screen is 0, but since the input has not been echoed in
   the log file, the column in the log file is usually not 0, and
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_terpricm_fresh-line.html" target="_top"><code class="function">FRESH-LINE</code></a> <span class="strong"><strong>must</strong></span> output a newline. Then a blank
   line is visible on the screen.)</li><li class="listitem">What happens if <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_terpricm_fresh-line.html" target="_top"><code class="function">FRESH-LINE</code></a> omits a newline when it
   would be needed?
   (This is more rare, but can happen, for example, when standard output
   and standard error are different streams but are joined outside the
   Lisp implementation, at the OS level.
   Such as in <span class="command"><strong>lisp | cat</strong></span>.)</li><li class="listitem"><p>Is it possible to reliably output a blank line
     before or after a paragraph of text? I.e. what happens with
   </p><div class="orderedlist"><ol class="orderedlist" type="A"><li class="listitem"><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
        <span class="format"><span class="quote">“<span class="quote">~%~%First line.~%Second line.</span>”</span></span>
      </li><li class="listitem">
        <span class="format"><span class="quote">“<span class="quote">~%First line.~%Second line.~%</span>”</span></span>
    </li></ol></div></li><li class="listitem"><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
        <span class="format"><span class="quote">“<span class="quote">~&amp;~%First line.~%Second line.~%</span>”</span></span>
      </li><li class="listitem">
        <span class="format"><span class="quote">“<span class="quote">~&amp;First line.~%Second line.~%~%</span>”</span></span>
    </li></ol></div></li><li class="listitem"><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
        <span class="format"><span class="quote">“<span class="quote">~%First line.~%Second line.~%</span>”</span></span>
      </li><li class="listitem">
        <span class="format"><span class="quote">“<span class="quote">First line.~%Second line.~%~%</span>”</span></span>
 </li></ol></div></li></ol></div></li><li class="listitem">Is it possible to optimize away blank lines?
   I.e. is it possible to avoid a blank line even though another piece
   of code uses one of A1 ... C2, without risking that adjacent lines be
   unseparated?</li></ol></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="nl-trad-analysis"></a>21.6.2. Analysis</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="strong"><strong>A</strong></span>: No extra blank lines.</li><li class="listitem"><span class="strong"><strong>AB</strong></span>: An extra blank line each time one
     switches from convention <span class="strong"><strong>B</strong></span> to <span class="strong"><strong>A</strong></span>.</li><li class="listitem"><span class="strong"><strong>B</strong></span>: No extra blank lines.</li><li class="listitem"><span class="strong"><strong>BC</strong></span>: No extra blank lines.</li><li class="listitem"><span class="strong"><strong>C</strong></span>: No extra blank lines.</li></ul></div></li><li class="listitem"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="strong"><strong>A</strong></span>: No extra blank lines.</li><li class="listitem"><span class="strong"><strong>AB</strong></span>: Blank lines can occur when
     convention <span class="strong"><strong>B</strong></span> is used.</li><li class="listitem"><span class="strong"><strong>B</strong></span>: Blank lines can occur.</li><li class="listitem"><span class="strong"><strong>BC</strong></span>: Blank lines can occur when
     convention <span class="strong"><strong>B</strong></span> is used.</li><li class="listitem"><span class="strong"><strong>C</strong></span>: No extra blank lines.</li></ul></div></li><li class="listitem"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="strong"><strong>A</strong></span>: No problem.</li><li class="listitem"><span class="strong"><strong>AB</strong></span>: Lines can be unseparated when one
     switches from convention <span class="strong"><strong>A</strong></span> to <span class="strong"><strong>B</strong></span>.</li><li class="listitem"><span class="strong"><strong>B</strong></span>: No problem.</li><li class="listitem"><span class="strong"><strong>BC</strong></span>: No problem.</li><li class="listitem"><span class="strong"><strong>C</strong></span>: No problem.</li></ul></div></li><li class="listitem"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="strong"><strong>A</strong></span>: No problem.</li><li class="listitem"><span class="strong"><strong>AB</strong></span>: The blank line is omitted when using
     A2 before switching to <span class="strong"><strong>B</strong></span>.</li><li class="listitem"><span class="strong"><strong>B</strong></span>: No problem.</li><li class="listitem"><span class="strong"><strong>BC</strong></span>: No problem.</li><li class="listitem"><span class="strong"><strong>C</strong></span>: No problem.</li></ul></div></li><li class="listitem"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="strong"><strong>A</strong></span>: Yes, using
     <span class="format"><span class="quote">“<span class="quote">~&amp;First line.~%Second line.</span>”</span></span>
     eats a previous blank line.</li><li class="listitem"><span class="strong"><strong>AB</strong></span>: Not really: Using
     <span class="format"><span class="quote">“<span class="quote">~&amp;First line.~%Second line.</span>”</span></span>
     may eat a previous blank line or a following blank line, but you
     cannot know in advance which one.</li><li class="listitem"><span class="strong"><strong>B</strong></span>: Yes, using
     <span class="format"><span class="quote">“<span class="quote">~&amp;First line.~%Second line.</span>”</span></span>
     eats a following blank line.</li><li class="listitem"><span class="strong"><strong>BC</strong></span>: Impossible.</li><li class="listitem"><span class="strong"><strong>C</strong></span>: Impossible.
     To optimize blank lines in case <span class="strong"><strong>C</strong></span> would require the opposite of
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_terpricm_fresh-line.html" target="_top"><code class="function">FRESH-LINE</code></a>, namely a conditional newline that is annullated if the
     <span class="emphasis"><em>next</em></span> output on the stream will be a
     newline. (<a class="link" href="#elastic-newline" title="21.11. Function EXT:ELASTIC-NEWLINE"><code class="function">EXT:ELASTIC-NEWLINE</code></a>, see below.)</li></ul></div></li></ol></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="nl-conclusion"></a>21.6.3. Conclusion</h3></div></div></div><p>Each approach has its advantages and disadvantages.</p><p>When used globally (i.e. no interoperability requirements),
 <span class="strong"><strong>A</strong></span>, <span class="strong"><strong>B</strong></span>, <span class="strong"><strong>C</strong></span> can be compared as follows:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="strong"><strong>A</strong></span> and <span class="strong"><strong>C</strong></span> are equally perfect if eating
    blank lines is not a requirement.</li><li class="listitem">If eating blank lines is desirable, <span class="strong"><strong>A</strong></span> is perfect.
  </li><li class="listitem"><span class="strong"><strong>B</strong></span> is not so good, because it is suboptimal in case 2.
</li></ul></div><p>For <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> built-ins, however, the interoperability requirement
 with both <span class="strong"><strong>A</strong></span> and <span class="strong"><strong>C</strong></span> is a major requirement. Therefore we have
 to choose <span class="strong"><strong>B</strong></span>, and accept the drawbacks:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="strong"><strong>AB</strong></span>: An extra blank line each time one
    switches from convention <span class="strong"><strong>B</strong></span> to <span class="strong"><strong>A</strong></span>.</li><li class="listitem"><span class="strong"><strong>B</strong></span>: When logging to a file, blank lines can
    occur.</li><li class="listitem"><span class="strong"><strong>AB</strong></span>: When joining two output streams into
    one, lines can be unseparated.</li><li class="listitem"><span class="strong"><strong>AB</strong></span>: Blank lines after a paragraph can be
    eaten by <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.</li><li class="listitem"><span class="strong"><strong>AB</strong></span>: Optimizing blank lines is not really
    possible.</li></ul></div><p>
 And to minimize the drawbacks, we recommend the user programs to use
 approach <span class="strong"><strong>B</strong></span> or <span class="strong"><strong>C</strong></span>, but not <span class="strong"><strong>A</strong></span>.</p><p>Another drawback of <span class="strong"><strong>B</strong></span> is, however, that in interactive sessions
 the cursor is nearly always positioned at the beginning of a line,
 pointing the user's focus to the wrong point and taking away a screen
 line.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="nl-solution"></a>21.6.4. Solution</h3></div></div></div><p>To solve this, we introduce the concept of an <strong class="first"><em class="firstterm">elastic
  newline</em></strong>, output by the function <a class="link" href="#elastic-newline" title="21.11. Function EXT:ELASTIC-NEWLINE"><code class="function">EXT:ELASTIC-NEWLINE</code></a>.
 This is the converse of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_terpricm_fresh-line.html" target="_top"><code class="function">FRESH-LINE</code></a>: It waits for the next character
 and outputs a newline when the next character is not a newline; then
 the next character is processed normally.
 As a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> directive, we write it <a class="link" href="#format-dot"><code class="literal">~.</code></a>.
 <a class="link" href="#elastic-newline" title="21.11. Function EXT:ELASTIC-NEWLINE"><code class="function">EXT:ELASTIC-NEWLINE</code></a> followed by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_terpricm_fresh-line.html" target="_top"><code class="function">FRESH-LINE</code></a> leads to exactly one newline
 always.</p><p>Elastic newline leads to a slightly different newline convention:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="strong"><strong>B'</strong></span>:
   Print a newline if needed before the line, and a newline if needed after it.
   As a format string:
   <span class="format"><span class="quote">“<span class="quote">~&amp;First line.~%Second line.~.</span>”</span></span>
</li></ul></div><p>The five programs being considered are now:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="strong"><strong>A</strong></span>: using convention <span class="strong"><strong>A</strong></span> exclusively,
 </li><li class="listitem"><span class="strong"><strong>AB'</strong></span>: mixing conventions <span class="strong"><strong>A</strong></span> and <span class="strong"><strong>B'</strong></span>,
 </li><li class="listitem"><span class="strong"><strong>B'</strong></span>: using convention <span class="strong"><strong>B'</strong></span> exclusively,
 </li><li class="listitem"><span class="strong"><strong>B'C</strong></span>: mixing conventions <span class="strong"><strong>B'</strong></span> and <span class="strong"><strong>C</strong></span>,
 </li><li class="listitem"><span class="strong"><strong>C</strong></span>: using convention <span class="strong"><strong>C</strong></span> exclusively,
</li></ul></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="nl-elnl-analysis"></a>21.6.5. Elastic Newline Analysis</h3></div></div></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="strong"><strong>A</strong></span>: No extra blank lines.</li><li class="listitem"><span class="strong"><strong>AB'</strong></span>: No extra blank lines.</li><li class="listitem"><span class="strong"><strong>B'</strong></span>: No extra blank lines.</li><li class="listitem"><span class="strong"><strong>B'C</strong></span>: No extra blank lines.</li><li class="listitem"><span class="strong"><strong>C</strong></span>: No extra blank lines.</li></ul></div></li><li class="listitem"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="strong"><strong>A</strong></span>: No extra blank lines.</li><li class="listitem"><span class="strong"><strong>AB'</strong></span>: Blank lines can occur when
     convention <span class="strong"><strong>B'</strong></span> is used.</li><li class="listitem"><span class="strong"><strong>B'</strong></span>: Blank lines can occur.</li><li class="listitem"><span class="strong"><strong>B'C</strong></span>: Blank lines can occur when
     convention <span class="strong"><strong>B'</strong></span> is used.</li><li class="listitem"><span class="strong"><strong>C</strong></span>: No extra blank lines.</li></ul></div></li><li class="listitem"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="strong"><strong>A</strong></span>: No problem.</li><li class="listitem"><span class="strong"><strong>AB'</strong></span>: Lines can be unseparated when one
     switches from convention <span class="strong"><strong>A</strong></span> to <span class="strong"><strong>B'</strong></span>.</li><li class="listitem"><span class="strong"><strong>B'</strong></span>: Lines can be unseparated when one
     switches from one stream to another without performing a
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_finish-ou_clear-output.html" target="_top"><code class="function">FORCE-OUTPUT</code></a>. This is a general problem with buffered streams;
     <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>'s <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_terpricm_fresh-line.html" target="_top"><code class="function">FRESH-LINE</code></a> contains a workaround that is limited to
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-OUTPUT*</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*ERROR-OUTPUT*</code></a>.</li><li class="listitem"><span class="strong"><strong>B'C</strong></span>: No problem.</li><li class="listitem"><span class="strong"><strong>C</strong></span>: No problem.</li></ul></div></li><li class="listitem"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="strong"><strong>A</strong></span>: No problem.</li><li class="listitem"><span class="strong"><strong>AB'</strong></span>: The blank line is omitted when
     using A2 before switching to <span class="strong"><strong>B'</strong></span> or when using B2 before switching
     to <span class="strong"><strong>A</strong></span>.</li><li class="listitem"><span class="strong"><strong>B'</strong></span>: No problem.</li><li class="listitem"><span class="strong"><strong>B'C</strong></span>: No problem.</li><li class="listitem"><span class="strong"><strong>C</strong></span>: No problem.</li></ul></div></li><li class="listitem"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="strong"><strong>A</strong></span>: Yes, using
     <span class="format"><span class="quote">“<span class="quote">~&amp;First line.~%Second line.</span>”</span></span>
     eats a previous blank line.</li><li class="listitem"><span class="strong"><strong>AB'</strong></span>: Not really: Using
     <span class="format"><span class="quote">“<span class="quote">~&amp;First line.~%Second line.</span>”</span></span>
     may eat a previous blank line or a following blank line, but you
     cannot know in advance which one.</li><li class="listitem"><span class="strong"><strong>B'</strong></span>: Yes, using
     <span class="format"><span class="quote">“<span class="quote">~&amp;First line.~%Second line.</span>”</span></span>
     eats a following blank line.</li><li class="listitem"><span class="strong"><strong>B'C</strong></span>: Impossible.</li><li class="listitem"><span class="strong"><strong>C</strong></span>: Yes, using
     <span class="format"><span class="quote">“<span class="quote">First line.~%Second line.~.</span>”</span></span>
     eats a following blank line.</li></ul></div></li></ol></div><p>Now criterium 1 is satisfied perfectly. We therefore choose
 <span class="strong"><strong>B'</strong></span>, not <span class="strong"><strong>B</strong></span>, for use inside <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>, and programs can use
 either <span class="strong"><strong>A</strong></span> or <span class="strong"><strong>C</strong></span> without problems during normal operation.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="stream-extfmt"></a>21.7. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-external-format.html" target="_top"><code class="function">STREAM-EXTERNAL-FORMAT</code></a></h2></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-external-format.html" target="_top"><code class="function">STREAM-EXTERNAL-FORMAT</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>able: <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-external-format.html" target="_top"><code class="function">STREAM-EXTERNAL-FORMAT</code></a> <em class="replaceable"><code>stream</code></em> [<em class="replaceable"><code>direction</code></em>]) <em class="replaceable"><code>encoding</code></em>)</code>,
 <em class="replaceable"><code>direction</code></em> can be <code class="constant">:INPUT</code>, <code class="constant">:OUTPUT</code>, or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
 If no <em class="replaceable"><code>direction</code></em> is given, the operation is nonrecursive.</p><p>This will <span class="strong"><strong>not</strong></span> work on <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stterminal-iost.html" target="_top"><code class="varname">*TERMINAL-IO*</code></a> et al, use <a href="impnotes.html#term-enc" class="olink"><code class="varname">CUSTOM:*TERMINAL-ENCODING*</code></a>
 instead.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="stream-eltype"></a>21.8. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#bin-stdio">21.8.1. Binary input from <code class="varname">*STANDARD-INPUT*</code></a></span></dt></dl></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>able. The <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> of
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s created by the functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_open.html" target="_top"><code class="function">OPEN</code></a>, <a class="link" href="#pipe" title="32.7.2. Pipes"><code class="function">EXT:MAKE-PIPE-INPUT-STREAM</code></a>
  <a class="link" href="#pipe" title="32.7.2. Pipes"><code class="function">EXT:MAKE-PIPE-OUTPUT-STREAM</code></a>, <a class="link" href="#pipe" title="32.7.2. Pipes"><code class="function">EXT:MAKE-PIPE-IO-STREAM</code></a>, <a class="link" href="#so-accept"><code class="function">SOCKET:SOCKET-ACCEPT</code></a>, <a class="link" href="#so-connect"><code class="function">SOCKET:SOCKET-CONNECT</code></a>
  can be modified, if the old and the new <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a>s are either
 </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">both equivalent to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a> or
    <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span> or <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_signed-byte.html" target="_top"><code class="classname">SIGNED-BYTE</code></a> 8)</code></span>; or</li><li class="listitem">both equivalent to <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> <em class="replaceable"><code>n</code></em>)</code></span> or <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_signed-byte.html" target="_top"><code class="classname">SIGNED-BYTE</code></a> <em class="replaceable"><code>n</code></em>)</code></span>, with the
    same <em class="replaceable"><code>n</code></em>.</li></ul></div><p>Functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> and <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a>)</code> are <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_generic-function.html" target="_top"><code class="classname">GENERIC-FUNCTION</code></a>s, see
 <a class="xref" href="#gray" title="Chapter 30. Gray streams">Chapter 30, <em>Gray streams</em></a>.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="stream-eltype-stdio"></a>Warning</h3><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> expects to be able to
  do <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a> i/o on standard streams like <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stterminal-iost.html" target="_top"><code class="varname">*TERMINAL-IO*</code></a>,
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-OUTPUT*</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-INPUT*</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*ERROR-OUTPUT*</code></a>,
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*QUERY-IO*</code></a> et al, thus it is a <span class="strong"><strong>very</strong></span> bad idea
  to change their <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> even when you can. Use
  <a class="link" href="#make-stream" title="21.9. Function EXT:MAKE-STREAM"><code class="function">EXT:MAKE-STREAM</code></a> instead, see <a class="xref" href="#bin-stdio" title="21.8.1. Binary input from *STANDARD-INPUT*">Section 21.8.1, “Binary input from <code class="varname">*STANDARD-INPUT*</code>”</a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="bin-stdio"></a>21.8.1. Binary input from <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-INPUT*</code></a></h3></div></div></div><p>Note that you cannot change <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> for some
 built-in streams, such as <a class="link" href="#terminal" title="21.2. Terminal interaction">terminal streams</a>,
 which is normally the value of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stterminal-iost.html" target="_top"><code class="varname">*TERMINAL-IO*</code></a>.
 Since <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-INPUT*</code></a> normally is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_synonym-stream.html" target="_top"><code class="classname">SYNONYM-STREAM</code></a> pointing
 to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stterminal-iost.html" target="_top"><code class="varname">*TERMINAL-IO*</code></a>, you cannot use <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-byte.html" target="_top"><code class="function">READ-BYTE</code></a> on it.</p><p>Since <a class="ulink" href="https://en.wikipedia.org/wiki/Common_Gateway_Interface" target="_top">CGI</a>
 (Common Gateway Interface) provides the form data for
 <span class="command"><strong>METHOD="POST"</strong></span> on the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/stdin.html"><code class="varname">stdin</code></a>,
 and the server will <span class="strong"><strong>not</strong></span> send you an <code class="literal"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#end-of-stream">end-of-stream</a></code> on the end of the data,
 you will need to use
 <code class="code">(<a class="link" href="#getenv" title="32.8. Operating System Environment"><code class="function">EXT:GETENV</code></a> <code class="envar">"CONTENT_LENGTH"</code>)</code>
 to determine how much data you should read from <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/stdin.html"><code class="varname">stdin</code></a>.
 <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> will detect that <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/stdin.html"><code class="varname">stdin</code></a> is not a terminal and create a regular
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_file-stream.html" target="_top"><code class="classname">FILE-STREAM</code></a> which can be passed to <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a>)</code>.
 To test this functionality interactively,
 you will need to open the standard input in the binary mode:
</p><pre class="programlisting">
(let ((buf (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-array.html" target="_top"><code class="function">MAKE-ARRAY</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_parse-integer.html" target="_top"><code class="function">PARSE-INTEGER</code></a> (<a class="link" href="#getenv" title="32.8. Operating System Environment"><code class="function">EXT:GETENV</code></a> "CONTENT_LENGTH"))
                       :element-type '<span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span>)))
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-open-stream.html" target="_top"><code class="function">WITH-OPEN-STREAM</code></a> (in (<a class="link" href="#make-stream" title="21.9. Function EXT:MAKE-STREAM"><code class="function">EXT:MAKE-STREAM</code></a> <code class="constant">:INPUT</code> <a class="link" href="#eltype"><code class="constant">:ELEMENT-TYPE</code></a> '<span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span>))
    (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-sequence.html" target="_top"><code class="function">READ-SEQUENCE</code></a> buf in))
  buf)
</pre></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="make-stream"></a>21.9. Function <a class="link" href="#make-stream" title="21.9. Function EXT:MAKE-STREAM"><code class="function">EXT:MAKE-STREAM</code></a></h2></div></div></div><p>Function <a class="link" href="#make-stream" title="21.9. Function EXT:MAKE-STREAM"><code class="function">EXT:MAKE-STREAM</code></a> creates a Lisp stream out of an OS <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a>:
 <code class="code">(<a class="link" href="#make-stream" title="21.9. Function EXT:MAKE-STREAM"><code class="function">EXT:MAKE-STREAM</code></a> <em class="replaceable"><code>object</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:DIRECTION</code>
  <a class="link" href="#eltype"><code class="constant">:ELEMENT-TYPE</code></a> <a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a> <a class="link" href="#buffered"><code class="constant">:BUFFERED</code></a>)</code></p><p><em class="replaceable"><code>object</code></em> designates an OS handle (a <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a>),
 and should be one of the following: </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">number</span></dt><dd>denotes the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a> of this value
  </dd><dt><span class="term"><code class="constant">:INPUT</code></span></dt><dd>denotes <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
    process standard input, that is, the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a> corresponding to <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/stdin.html"><code class="varname">stdin</code></a>
    (0 on <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>)</dd><dt><span class="term"><code class="constant">:OUTPUT</code></span></dt><dd>denotes <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
    process standard output, that is, the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a> corresponding to <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/stdout.html"><code class="varname">stdout</code></a>
    (1 on <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>)</dd><dt><span class="term"><code class="constant">:ERROR</code></span></dt><dd>denotes <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
    process error output, that is, the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a> corresponding to <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/stderr.html"><code class="varname">stderr</code></a>
    (2 on <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>)</dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a></span></dt><dd>denotes the handle of this stream, which should be
     a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_file-stream.html" target="_top"><code class="classname">FILE-STREAM</code></a> or a <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-STREAM</code></a></dd></dl></div><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="make-stream-warn-buffering"></a>Beware of buffering!</h3><p>When there are several Lisp <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s backed by the same OS
  <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a>, the behavior may be highly confusing when some of the
  Lisp streams are <a class="link" href="#buffered"><code class="constant">:BUFFERED</code></a>.  Use <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_finish-ou_clear-output.html" target="_top"><code class="function">FORCE-OUTPUT</code></a> for <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_o.html#output">output</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s,
  and <a class="link" href="#bulk-io" title="21.4. Bulk Input and Output">bulk input</a> for <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_i.html#input">input</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s.</p></div><p>The handle is duplicated (with <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/dup.html"><code class="function">dup</code></a>),
 so it is safe to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a> a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> returned by <a class="link" href="#make-stream" title="21.9. Function EXT:MAKE-STREAM"><code class="function">EXT:MAKE-STREAM</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="file-pos"></a>21.10. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_file-position.html" target="_top"><code class="function">FILE-POSITION</code></a></h2></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_file-position.html" target="_top"><code class="function">FILE-POSITION</code></a> works on any <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_file-stream.html" target="_top"><code class="classname">FILE-STREAM</code></a>.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platform only.</span></span></span></dt><dd>When a <span class="keysym">#\Newline</span> is output to (respectively input from)
  a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_file-stream.html" target="_top"><code class="classname">FILE-STREAM</code></a>, its file position is increased by 2 since <span class="keysym">#\Newline</span> is
  encoded as <span class="keycode">CR</span>/<span class="keycode">LF</span> in the file.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="elastic-newline"></a>21.11. Function <a class="link" href="#elastic-newline" title="21.11. Function EXT:ELASTIC-NEWLINE"><code class="function">EXT:ELASTIC-NEWLINE</code></a></h2></div></div></div><p>The function <code class="code">(<a class="link" href="#elastic-newline" title="21.11. Function EXT:ELASTIC-NEWLINE"><code class="function">EXT:ELASTIC-NEWLINE</code></a> [<em class="replaceable"><code>stream</code></em>])</code> is like
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_terpricm_fresh-line.html" target="_top"><code class="function">FRESH-LINE</code></a> but the other way around: It outputs a conditional newline
 on <em class="replaceable"><code>stream</code></em>, which is canceled if the <span class="emphasis"><em>next</em></span>
 output on <em class="replaceable"><code>stream</code></em> happens to be a newline.  More precisely, it
 causes a newline to be output right before the next character is
 written on <em class="replaceable"><code>stream</code></em>, if this character is not a newline.
 The newline is also output if the next operation on the stream is
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_terpricm_fresh-line.html" target="_top"><code class="function">FRESH-LINE</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_finish-ou_clear-output.html" target="_top"><code class="function">FINISH-OUTPUT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_finish-ou_clear-output.html" target="_top"><code class="function">FORCE-OUTPUT</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a>.</p><p>The functionality of <a class="link" href="#elastic-newline" title="21.11. Function EXT:ELASTIC-NEWLINE"><code class="function">EXT:ELASTIC-NEWLINE</code></a> is also available through
 the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> directive <a class="link" href="#format-dot"><code class="literal">~.</code></a>.</p><p>A technique for avoiding unnecessary blank lines in output is to
 begin each chunk of output with a call to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_terpricm_fresh-line.html" target="_top"><code class="function">FRESH-LINE</code></a> and to terminate it
 with a call to <a class="link" href="#elastic-newline" title="21.11. Function EXT:ELASTIC-NEWLINE"><code class="function">EXT:ELASTIC-NEWLINE</code></a>.</p><p>See also <a class="xref" href="#newline-convention" title="21.6. Newline Convention">Section 21.6, “Newline Convention”</a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="open"></a>21.12. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_open.html" target="_top"><code class="function">OPEN</code></a></h2></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_open.html" target="_top"><code class="function">OPEN</code></a> accepts an additional keyword <a class="link" href="#buffered"><code class="constant">:BUFFERED</code></a>.</p><div class="variablelist"><p class="title"><strong>The acceptable values for the arguments to the
   <a class="link" href="#open" title="21.12. Function OPEN">file</a>/<a class="link" href="#pipe" title="32.7.2. Pipes">pipe</a>/<a class="link" href="#socket" title="32.4. Socket Streams">socket</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> functions</strong></p><dl class="variablelist"><dt><a id="eltype"></a><span class="term"><a class="link" href="#eltype"><code class="constant">:ELEMENT-TYPE</code></a></span></dt><dd><p class="simpara">types equivalent to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a> or
    <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> <em class="replaceable"><code>n</code></em>)</code></span>, <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_signed-byte.html" target="_top"><code class="classname">SIGNED-BYTE</code></a> <em class="replaceable"><code>n</code></em>)</code></span>; if the stream is to be
    un<a class="link" href="#buffered"><code class="constant">:BUFFERED</code></a>, <em class="replaceable"><code>n</code></em> must be a multiple of 8.</p><p class="simpara">If <em class="replaceable"><code>n</code></em> is not a multiple of 8, <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> will use the
    specified number of bits for i/o, and write the file length
    (as a number of <em class="replaceable"><code>n</code></em>-bit bytes) in the preamble.</p><p class="simpara">This is done to ensure the input/output consistency:
    suppose you open a file with <a class="link" href="#eltype"><code class="constant">:ELEMENT-TYPE</code></a> of <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 3)</code></span> and write 7 bytes
    (i.e., 21 bit) there.
    The underlying OS can do input/output only in whole 8-bit bytes.
    Thus the OS will report the size of the file as 3 (8-bit) bytes.
    Without the preamble <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> will have no way to know how many
    3-bit bytes to read from this file - 6, 7 or 8.</p><p class="simpara">See also <a class="xref" href="#stream-eltype" title="21.8. Function STREAM-ELEMENT-TYPE">Section 21.8, “Function <code class="function">STREAM-ELEMENT-TYPE</code>”</a>.</p></dd><dt><a id="extfmt"></a><span class="term"><a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a></span></dt><dd><p class="simpara"><a class="link" href="#encoding" title="31.5. Encodings"><code class="classname">EXT:ENCODING</code></a>s, (constant) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>s in the
    <a class="link" href="#encoding" title="31.5. Encodings"><strong class="package"><span class="quote">“<span class="quote">CHARSET</span>”</span></strong></a> package, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>s (denoting <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/iconv.html"><code class="function">iconv</code></a>-based encodings),
    the symbol <code class="constant">:DEFAULT</code>, and the <a class="link" href="#newline" title="31.5.3. Line Terminators">line terminator</a> keywords
    <code class="constant">:UNIX</code>, <code class="constant">:MAC</code>, <code class="constant">:DOS</code>.  The default encoding is <a href="impnotes.html#def-file-enc" class="olink"><code class="varname">CUSTOM:*DEFAULT-FILE-ENCODING*</code></a>.
    This argument determines how the lisp <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a> data is
    converted to/from the 8-bit bytes that the underlying OS uses.</p><p class="simpara">See also <a class="xref" href="#stream-extfmt" title="21.7. Function STREAM-EXTERNAL-FORMAT">Section 21.7, “Function <code class="function">STREAM-EXTERNAL-FORMAT</code>”</a>.</p></dd><dt><a id="buffered"></a><span class="term"><a class="link" href="#buffered"><code class="constant">:BUFFERED</code></a></span></dt><dd><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>, or <code class="constant">:DEFAULT</code>.
    Have <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> manage an internal buffer for input or output (in
    addition to the buffering that might be used by the underlying OS).
    Buffering is a known general technique to significantly speed up i/o.
  </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">for functions that create <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-STREAM</code></a>s and
    <a class="link" href="#pipe" title="32.7.2. Pipes">pipes</a>, <code class="constant">:DEFAULT</code> is equivalent to
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> on the input side and to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> on the output side; if you are
    transmitting a lot of data then using buffering
    will significantly speed up your i/o;</li><li class="listitem">for functions that <a class="link" href="#open" title="21.12. Function OPEN">open</a>
    files, <code class="constant">:DEFAULT</code> means that buffered file streams will be returned
    for regular files and (on <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>) block-devices, and unbuffered file
    streams for special files.</li></ul></div><p>
  Note that some files, notably those on the <code class="filename">/proc</code>
  filesystem (on <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> systems), are actually, despite their innocuous
  appearance, special files, so you might need to supply an explicit
  <a class="link" href="#buffered"><code class="constant">:BUFFERED</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> argument for them.  Actually, <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> detects that
  the file is a <code class="filename">/proc</code> file, so that one is covered,
  but there are probably more strange beasts out there!
</p></dd></dl></div><div class="simplesect"><div class="titlepage"><div><div><h3 class="title"><a id="reopen"></a>Variable <a class="link" href="#reopen" title="Variable CUSTOM:*REOPEN-OPEN-FILE*"><code class="varname">CUSTOM:*REOPEN-OPEN-FILE*</code></a></h3></div></div></div><p>When an already opened file is opened again, and <span class="strong"><strong>not</strong></span> both the
 existing and the new <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s are read-only (i.e., <code class="constant">:DIRECTION</code> is
 <code class="constant">:INPUT</code> or <code class="constant">:INPUT-IMMUTABLE</code>), the streams can
 mess up each other and produce unexpected results.
 The user variable <strong class="first"><em class="firstterm"><a class="link" href="#reopen" title="Variable CUSTOM:*REOPEN-OPEN-FILE*"><code class="varname">CUSTOM:*REOPEN-OPEN-FILE*</code></a></em></strong> controls how <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
 handles the situation and can take 4 values: </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></span></dt><dd>
     do nothing: do not even check that there are other <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s
     pointing to the same file</dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_warn.html" target="_top"><code class="function">WARN</code></a></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a> a
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_warning.html" target="_top"><code class="classname">WARNING</code></a> and proceed</dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a>
     the <span class="emphasis"><em>other</em></span> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s and proceed
     (this could be dangerous and is not generally recommended)
  </dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_error.html" target="_top"><code class="function">ERROR</code></a> (default)</span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>
     a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#continuable">continuable</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a></dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="clear-input"></a>21.13. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_clear-input.html" target="_top"><code class="function">CLEAR-INPUT</code></a></h2></div></div></div><p>Calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_clear-input.html" target="_top"><code class="function">CLEAR-INPUT</code></a> on a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> removes the <code class="literal"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#end-of-stream">end-of-stream</a></code> state,
 thus making it available for further input.</p><p>This allows reading from a file as it is being appended to,
as if with <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/tail.html"><span class="command"><strong>tail -f</strong></span></a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="close"></a>21.14. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a></h2></div></div></div><p>Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a> is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_generic-function.html" target="_top"><code class="classname">GENERIC-FUNCTION</code></a>, see
 <a class="xref" href="#gray" title="Chapter 30. Gray streams">Chapter 30, <em>Gray streams</em></a>.</p><p>When the <code class="constant">:ABORT</code> argument is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a> will not
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> even when the underlying OS call fails.</p><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_get-outpu_tream-string.html" target="_top"><code class="function">GET-OUTPUT-STREAM-STRING</code></a> returns the same value after
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a> as it would before it.</p><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a> on an already closed <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> does nothing and returns
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.</p><p>If you do not <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a> your <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> explicitly, it will be
 closed at <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion time automatically
 (with <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a> <em class="replaceable"><code>stream</code></em> <code class="constant">:ABORT</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>)</code>).
 This is <span class="strong"><strong>not</strong></span> recommended though because <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion is not deterministic.
 Please use <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-open-stream.html" target="_top"><code class="function">WITH-OPEN-STREAM</code></a> etc.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="open-stream-p"></a>21.15. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_open-stream-p.html" target="_top"><code class="function">OPEN-STREAM-P</code></a></h2></div></div></div><p>Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_open-stream-p.html" target="_top"><code class="function">OPEN-STREAM-P</code></a> is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_generic-function.html" target="_top"><code class="classname">GENERIC-FUNCTION</code></a>, see
 <a class="xref" href="#gray" title="Chapter 30. Gray streams">Chapter 30, <em>Gray streams</em></a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="broadcast-stream"></a>21.16. Class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_broadcast-stream.html" target="_top"><code class="classname">BROADCAST-STREAM</code></a></h2></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_input-str_put-stream-p.html" target="_top"><code class="function">INPUT-STREAM-P</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_interactive-stream-p.html" target="_top"><code class="function">INTERACTIVE-STREAM-P</code></a> return false for
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_broadcast-stream.html" target="_top"><code class="classname">BROADCAST-STREAM</code></a>s.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="stream-buffer"></a>21.17. Functions
  <strong class="first"><em class="firstterm"><code class="function">EXT:MAKE-BUFFERED-INPUT-STREAM</code>
   <a id="stream-buffer-i" class="indexterm"></a></em></strong> and
  <strong class="first"><em class="firstterm"><code class="function">EXT:MAKE-BUFFERED-OUTPUT-STREAM</code>
   <a id="stream-buffer-o" class="indexterm"></a></em></strong>
 </h2></div></div></div><p><strong><code class="code">(EXT:MAKE-BUFFERED-OUTPUT-STREAM
   <em class="replaceable"><code>function</code></em>)</code>. </strong>Returns a buffered <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_o.html#output">output</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>.
 <em class="replaceable"><code>function</code></em> is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a> expecting one argument, a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-string.html" target="_top"><code class="classname">SIMPLE-STRING</code></a>.
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_write-char.html" target="_top"><code class="function">WRITE-CHAR</code></a> collects the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>s in a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>, until a
 newline character is written or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_finish-ou_clear-output.html" target="_top"><code class="function">FORCE-OUTPUT</code></a>/<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_finish-ou_clear-output.html" target="_top"><code class="function">FINISH-OUTPUT</code></a> is called.
 Then <em class="replaceable"><code>function</code></em> is called with a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-string.html" target="_top"><code class="classname">SIMPLE-STRING</code></a> as argument,
 that contains the characters collected so far.
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_finish-ou_clear-output.html" target="_top"><code class="function">CLEAR-OUTPUT</code></a> discards the characters collected so far.</p><p><strong><code class="code">(EXT:MAKE-BUFFERED-INPUT-STREAM <em class="replaceable"><code>function</code></em>
   <em class="replaceable"><code>mode</code></em>)</code>. </strong>Returns a buffered <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_i.html#input">input</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>.
 <em class="replaceable"><code>function</code></em> is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a> of 0 arguments that returns
 either <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> (stands for <code class="literal"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#end-of-stream">end-of-stream</a></code>) or up to three values
 <em class="replaceable"><code>string</code></em>, <em class="replaceable"><code>start</code></em>, <em class="replaceable"><code>end</code></em>.
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-char.html" target="_top"><code class="function">READ-CHAR</code></a> returns the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>s of the current <em class="replaceable"><code>string</code></em> one
 after another, as delimited by <em class="replaceable"><code>start</code></em> and <em class="replaceable"><code>end</code></em>, which default to
 <code class="literal">0</code> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, respectively.
 When the <em class="replaceable"><code>string</code></em> is consumed, <em class="replaceable"><code>function</code></em> is called again.
 The <em class="replaceable"><code>string</code></em> returned by <em class="replaceable"><code>function</code></em> should not be changed by the user.
 <em class="replaceable"><code>function</code></em> should copy the <em class="replaceable"><code>string</code></em> with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_copy-seq.html" target="_top"><code class="function">COPY-SEQ</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_subseq.html" target="_top"><code class="function">SUBSEQ</code></a> before
 returning if the original <em class="replaceable"><code>string</code></em> is to be modified.
 <em class="replaceable"><code>mode</code></em> determines the behavior of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_listen.html" target="_top"><code class="function">LISTEN</code></a>
 when the current <em class="replaceable"><code>string</code></em> buffer is empty:
 </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></span></dt><dd>the stream acts like a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_file-stream.html" target="_top"><code class="classname">FILE-STREAM</code></a>,
     i.e. <em class="replaceable"><code>function</code></em> is called</dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a></span></dt><dd>the stream acts like an interactive stream without
     <code class="literal"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#end-of-stream">end-of-stream</a></code>, i.e. one can assume that further characters will always
     arrive, without calling <em class="replaceable"><code>function</code></em></dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a></span></dt><dd>this <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a> tells, upon call, if further
     non-empty <em class="replaceable"><code>string</code></em>s are to be expected.</dd></dl></div><p>
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_clear-input.html" target="_top"><code class="function">CLEAR-INPUT</code></a> discards the rest of the current <em class="replaceable"><code>string</code></em>,
 so <em class="replaceable"><code>function</code></em> will be called upon the next <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-char.html" target="_top"><code class="function">READ-CHAR</code></a> operation.
</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="stream-handles"></a>21.18. Function
  <code class="function">EXT:STREAM-HANDLES</code></h2></div></div></div><p>The function <code class="code">(EXT:STREAM-HANDLES <em class="replaceable"><code>stream</code></em>)</code> returns
two values:</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">The OS <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a> for the <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_i.html#input">input</a> side of the
<em class="replaceable"><code>stream</code></em>, or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if the <em class="replaceable"><code>stream</code></em> is an <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_o.html#output">output</a>-only <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>
or if there is no <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a> associated with it.</li><li class="listitem">The OS <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a> for the <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_o.html#output">output</a> side of the
<em class="replaceable"><code>stream</code></em>, or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if the <em class="replaceable"><code>stream</code></em> is an <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_i.html#input">input</a>-only <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>
or if there is no <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a> associated with it.</li></ol></div><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>It is dangerous to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a> the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a>s returned by
this function.  This may lead to <code class="constant">EBADF</code>
OS <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>s and, eventually, segmentation faults.  Always use <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a>
on the original Lisp <em class="replaceable"><code>stream</code></em>s instead.</p></div></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="printer"></a>Chapter 22. Printer <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-22.html">[chap-22]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#multi-rep">22.1. Multiple Possible Textual Representations   sec_22-1-1-1</a></span></dt><dt><span class="section"><a href="#write-float-decimal">22.2. Printing Floats   sec_22-1-3-1-3</a></span></dt><dt><span class="section"><a href="#spacecharprint">22.3. Printing Characters   sec_22-1-3-2</a></span></dt><dt><span class="section"><a href="#sym-pack-prefix">22.4. Package Prefixes for Symbols   sec_22-1-3-3-1</a></span></dt><dt><span class="section"><a href="#print-vector">22.5. Printing Other Vectors   sec_22-1-3-7</a></span></dt><dt><span class="section"><a href="#print-array">22.6. Printing Other Arrays   sec_22-1-3-8</a></span></dt><dd><dl><dt><span class="section"><a href="#pathprint">22.6.1. Printing Pathnames   sec_22-1-3-11</a></span></dt></dl></dd><dt><span class="section"><a href="#clpp">22.7. The Lisp Pretty Printer   sec_22-2</a></span></dt><dd><dl><dt><span class="section"><a href="#pp-dispatch">22.7.1. Pretty Print Dispatch Table   sec_22-2-1-4</a></span></dt></dl></dd><dt><span class="section"><a href="#print-formatted">22.8. Formatted Output   sec_22-3</a></span></dt><dt><span class="section"><a href="#write">22.9. Functions <code class="function">WRITE</code> &amp; <code class="function">WRITE-TO-STRING</code></a></span></dt><dt><span class="section"><a href="#print-unreadable-object">22.10. Macro <code class="function">PRINT-UNREADABLE-OBJECT</code></a></span></dt><dt><span class="section"><a href="#print-misc">22.11. Miscellaneous Issues</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="multi-rep"></a>22.1. Multiple Possible Textual Representations
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-1-1-1.html">[sec_22-1-1-1]</a></h2></div></div></div><div class="simplesect"><div class="titlepage"><div><div><h3 class="title"><a id="pr-closure"></a>Variable <a class="link" href="#pr-closure" title="Variable CUSTOM:*PRINT-CLOSURE*"><code class="varname">CUSTOM:*PRINT-CLOSURE*</code></a></h3></div></div></div><p>An additional variable <a class="link" href="#pr-closure" title="Variable CUSTOM:*PRINT-CLOSURE*"><code class="varname">CUSTOM:*PRINT-CLOSURE*</code></a> controls whether compiled and
 interpreted functions (closures) are output in detailed form.
 If <a class="link" href="#pr-closure" title="Variable CUSTOM:*PRINT-CLOSURE*"><code class="varname">CUSTOM:*PRINT-CLOSURE*</code></a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, a readable syntax is used for closures:
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term">interpreted closures</span></dt><dd><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-13.html"><span class="data"><code class="literal">#S</code></span></a>(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a> ...)</dd><dt><span class="term">compiled closures</span></dt><dd><span class="data"><code class="literal">#Y(...)</code></span> (this is what you
would see if you open a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <code class="filename">#P".fas"</code> in a text editor)</dd></dl></div><p>This feature is turned off by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-stan_rd-io-syntax.html" target="_top"><code class="function">WITH-STANDARD-IO-SYNTAX</code></a> because
 it is easy to get wrong (see below) and non-portable.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>Closures often refer to value cells or other entities from the
<a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a>.  The correct operation of a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a> may depend on the access
to the same value cells as some other, related <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a>s.
If you want to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">WRITE</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_readcm_re_g-whitespace.html" target="_top"><code class="function">READ</code></a> back <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a>s so that their semantics
is preserved, you have to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">WRITE</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_readcm_re_g-whitespace.html" target="_top"><code class="function">READ</code></a> <span class="strong"><strong>all</strong></span> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a>s that share
some structure in the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a> <span class="emphasis"><em>together</em></span>, and you have to
either bind <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-readablyst.html" target="_top"><code class="varname">*PRINT-READABLY*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> or use <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-stan_rd-io-syntax.html" target="_top"><code class="function">WITH-STANDARD-IO-SYNTAX</code></a>:
</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_values.html" target="_top"><code class="function">VALUES</code></a> my-pop my-push)
      `(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET</code></a> ((storage ()))
         (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_values.html" target="_top"><code class="function">VALUES</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_lambda.html" target="_top"><code class="function">LAMBDA</code></a> () (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_pop.html" target="_top"><code class="function">POP</code></a> storage))
                 (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_lambda.html" target="_top"><code class="function">LAMBDA</code></a> (x) (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_push.html" target="_top"><code class="function">PUSH</code></a> x storage)))))
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET</code></a> ((pair (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-from-string.html" target="_top"><code class="function">READ-FROM-STRING</code></a>
             (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-stan_rd-io-syntax.html" target="_top"><code class="function">WITH-STANDARD-IO-SYNTAX</code></a>
               (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET</code></a> ((<a class="link" href="#pr-closure" title="Variable CUSTOM:*PRINT-CLOSURE*"><code class="varname">CUSTOM:*PRINT-CLOSURE*</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>))
                 (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_write-to-_nc-to-string.html" target="_top"><code class="function">PRIN1-TO-STRING</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_cons.html" target="_top"><code class="function">CONS</code></a> my-pop my-push)))))))
   (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/spefor_setq.html" target="_top"><code class="function">SETQ</code></a> my-pop-1 (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CAR</code></a> pair)
         my-push-1 (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDR</code></a> pair)))
</pre><p>
Note that <code class="function">my-pop</code> and <code class="function">my-push</code>
share environment between themselves but <span class="strong"><strong>not</strong></span> with
<code class="function">my-pop-1</code> and <code class="function">my-push-1</code> which
can be easily seen if you do </p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET</code></a> ((<a class="link" href="#pr-closure" title="Variable CUSTOM:*PRINT-CLOSURE*"><code class="varname">CUSTOM:*PRINT-CLOSURE*</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>) (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-circlest.html" target="_top"><code class="varname">*PRINT-CIRCLE*</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>))
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">PRINT</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_listcm_listst.html" target="_top"><code class="function">LIST</code></a> my-pop my-push my-pop-1 my-push-1)))
</pre><p> but which is not at all obvious from the usual
<a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html"><span class="data"><code class="literal">#&lt;</code></span></a> output.</p></div><p><a class="link" href="#pr-closure" title="Variable CUSTOM:*PRINT-CLOSURE*"><code class="varname">CUSTOM:*PRINT-CLOSURE*</code></a> is initially set to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</p></div><div class="simplesect"><div class="titlepage"><div><div><h3 class="title"><a id="pr-rpars"></a>Variable <a class="link" href="#pr-rpars" title="Variable CUSTOM:*PRINT-RPARS*"><code class="varname">CUSTOM:*PRINT-RPARS*</code></a></h3></div></div></div><p>An additional variable <a class="link" href="#pr-rpars" title="Variable CUSTOM:*PRINT-RPARS*"><code class="varname">CUSTOM:*PRINT-RPARS*</code></a> controls
 the output of the right (closing) parentheses.
 If <a class="link" href="#pr-rpars" title="Variable CUSTOM:*PRINT-RPARS*"><code class="varname">CUSTOM:*PRINT-RPARS*</code></a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, closing parentheses which do not fit onto
 the same line as the the corresponding opening parenthesis are output
 just below their corresponding opening parenthesis, in the same column.
 </p><p><a class="link" href="#pr-rpars" title="Variable CUSTOM:*PRINT-RPARS*"><code class="varname">CUSTOM:*PRINT-RPARS*</code></a> is initially set to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</p></div><div class="simplesect"><div class="titlepage"><div><div><h3 class="title"><a id="pr-indent"></a>Variable <a class="link" href="#pr-indent" title="Variable CUSTOM:*PRINT-INDENT-LISTS*"><code class="varname">CUSTOM:*PRINT-INDENT-LISTS*</code></a></h3></div></div></div><p>An additional variable <a class="link" href="#pr-indent" title="Variable CUSTOM:*PRINT-INDENT-LISTS*"><code class="varname">CUSTOM:*PRINT-INDENT-LISTS*</code></a> controls the indentation of
 lists that span more than one line.
 It specifies by how many characters items within the list will be
 indented relative to the beginning of the list.</p><p><a class="link" href="#pr-indent" title="Variable CUSTOM:*PRINT-INDENT-LISTS*"><code class="varname">CUSTOM:*PRINT-INDENT-LISTS*</code></a> is initially set to <code class="literal">1</code>.</p></div><div class="simplesect"><div class="titlepage"><div><div><h3 class="title"><a id="ppr-first-newline"></a>Variable <a class="link" href="#ppr-first-newline" title="Variable CUSTOM:*PPRINT-FIRST-NEWLINE*"><code class="varname">CUSTOM:*PPRINT-FIRST-NEWLINE*</code></a></h3></div></div></div><p>An additional variable <a class="link" href="#ppr-first-newline" title="Variable CUSTOM:*PPRINT-FIRST-NEWLINE*"><code class="varname">CUSTOM:*PPRINT-FIRST-NEWLINE*</code></a> controls
 pretty-printing of multi-line objects.
 When <a class="link" href="#ppr-first-newline" title="Variable CUSTOM:*PPRINT-FIRST-NEWLINE*"><code class="varname">CUSTOM:*PPRINT-FIRST-NEWLINE*</code></a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>,
 and the current line already has some characters on it,
 and the next object will be printed on several lines,
 and it does not start with a <span class="keysym">#\Newline</span>,
 then a <span class="keysym">#\Newline</span> is printed before the object.
 E.g., when you type <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> "return value: ~S~%" <em class="replaceable"><code>v</code></em>)</code>
 you want want to see a terse one-line output when <em class="replaceable"><code>v</code></em> is something
 short (like <code class="literal">0</code> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>), but you probably want to see
 something nice, like </p><pre class="screen">
return value:
(long list which does not fit
 on one line)</pre><p>
instead of </p><pre class="screen">
return value: (long list which does not fit
 on one line)</pre><p> when it does not.</p><p><a class="link" href="#ppr-first-newline" title="Variable CUSTOM:*PPRINT-FIRST-NEWLINE*"><code class="varname">CUSTOM:*PPRINT-FIRST-NEWLINE*</code></a> has no effect if <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-prettyst.html" target="_top"><code class="varname">*PRINT-PRETTY*</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</p><p><a class="link" href="#ppr-first-newline" title="Variable CUSTOM:*PPRINT-FIRST-NEWLINE*"><code class="varname">CUSTOM:*PPRINT-FIRST-NEWLINE*</code></a> is initially set to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="write-float-decimal"></a>22.2. Printing Floats
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-1-3-1-3.html">[sec_22-1-3-1-3]</a></h2></div></div></div><p>In the absence of <a class="link" href="#write-float-decimal" title="22.2. Printing Floats sec_22-1-3-1-3"><code class="function">SYS::WRITE-FLOAT-DECIMAL</code></a>, floating point numbers
 are output in radix 2.  This function is defined in <a class="link" href="#floatprint-lisp"><code class="filename">floatprint.lisp</code></a>
 and is not available if you run <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> without a <a href="impnotes.html#image" class="olink">memory image</a> (which
 you should never do anyway!)</p><p>If <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-readablyst.html" target="_top"><code class="varname">*PRINT-READABLY*</code></a> is true, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stread-de_oat-formatst.html" target="_top"><code class="varname">*READ-DEFAULT-FLOAT-FORMAT*</code></a>
 has no influence on the way <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_float.html" target="_top"><code class="classname">FLOAT</code></a>s are printed.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="spacecharprint"></a>22.3. Printing Characters
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-1-3-2.html">[sec_22-1-3-2]</a></h2></div></div></div><p>Characters are printed as specified in [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] using
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-1.html"><span class="data"><code class="literal">#\</code></span></a>, with one exception: when <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#printer_escaping">printer escaping</a> is in effect,
 the space character is printed as
 <span class="quote">“<span class="quote"><code class="computeroutput">#\Space</code></span>”</span> when the
 variable <a class="link" href="#spacecharprint" title="22.3. Printing Characters sec_22-1-3-2"><code class="varname">CUSTOM:*PRINT-SPACE-CHAR-ANSI*</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
 When <a class="link" href="#spacecharprint" title="22.3. Printing Characters sec_22-1-3-2"><code class="varname">CUSTOM:*PRINT-SPACE-CHAR-ANSI*</code></a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, it is printed as
 <span class="quote">“<span class="quote"><code class="computeroutput">#\ </code></span>”</span>; this is how
 [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] specifies it.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="sym-pack-prefix"></a>22.4. Package Prefixes for Symbols
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-1-3-3-1.html">[sec_22-1-3-3-1]</a></h2></div></div></div><p><a id="pr-sym-pack-prefix"></a><strong>Variable <a class="link" href="#pr-sym-pack-prefix" title="Variable CUSTOM:*PRINT-SYMBOL-PACKAGE-PREFIX-SHORTEST*"><code class="function">CUSTOM:*PRINT-SYMBOL-PACKAGE-PREFIX-SHORTEST*</code></a>. </strong>When <a class="link" href="#pr-sym-pack-prefix" title="Variable CUSTOM:*PRINT-SYMBOL-PACKAGE-PREFIX-SHORTEST*"><code class="function">CUSTOM:*PRINT-SYMBOL-PACKAGE-PREFIX-SHORTEST*</code></a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the package
  prefix is not the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_package-name.html" target="_top"><code class="function">PACKAGE-NAME</code></a> but the shortest (nick)name as
  returned by <a class="link" href="#package-shortest-name"><code class="function">EXT:PACKAGE-SHORTEST-NAME</code></a>.  This variable is ignored when
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-readablyst.html" target="_top"><code class="varname">*PRINT-READABLY*</code></a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="print-vector"></a>22.5. Printing Other Vectors
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-1-3-7.html">[sec_22-1-3-7]</a></h2></div></div></div><p>When <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-readablyst.html" target="_top"><code class="varname">*PRINT-READABLY*</code></a> is true, other vectors are written as
 follows: if the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_array-element-type.html" target="_top"><code class="function">ARRAY-ELEMENT-TYPE</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>, the syntax
 <code class="computeroutput">#(<em class="replaceable"><code>x<sub>1</sub></code></em> ... <em class="replaceable"><code>x<sub>n</sub></code></em>)</code> is used.
 Otherwise, the syntax <code class="computeroutput">#A(<em class="replaceable"><code>element-type</code></em>
  <em class="replaceable"><code>dimensions</code></em> <em class="replaceable"><code>contents</code></em>)</code> is used.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="print-array"></a>22.6. Printing Other Arrays
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-1-3-8.html">[sec_22-1-3-8]</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#pathprint">22.6.1. Printing Pathnames   sec_22-1-3-11</a></span></dt></dl></div><p>When <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-readablyst.html" target="_top"><code class="varname">*PRINT-READABLY*</code></a> is true, other arrays are written as
 follows: if the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_array-element-type.html" target="_top"><code class="function">ARRAY-ELEMENT-TYPE</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>, the syntax
 <code class="computeroutput"><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-12.html"><span class="data"><code class="literal">#<em class="replaceable"><code>rank</code></em>A</code></span></a> <em class="replaceable"><code>contents</code></em></code> is used.
 Otherwise, the syntax <code class="computeroutput">#A(<em class="replaceable"><code>element-type</code></em> <em class="replaceable"><code>dimensions</code></em>
 <em class="replaceable"><code>contents</code></em>)</code> is used.</p><p>As explicitly permitted by this section, specialized <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_bit.html" target="_top"><code class="classname">BIT</code></a> and
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_array.html" target="_top"><code class="classname">ARRAY</code></a>s are printed with the innermost lists generated
 by the printing algorithm being instead printed using <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_bit-vector.html" target="_top"><code class="classname">BIT-VECTOR</code></a> and
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> syntax, respectively.</p><p><a id="pr-empty-arr-ansi"></a><strong>Variable <a class="link" href="#pr-empty-arr-ansi" title="Variable CUSTOM:*PRINT-EMPTY-ARRAYS-ANSI*"><code class="varname">CUSTOM:*PRINT-EMPTY-ARRAYS-ANSI*</code></a>. </strong>Empty <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_array.html" target="_top"><code class="classname">ARRAY</code></a>s, i.e., arrays with no elements and zero
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_array-total-size.html" target="_top"><code class="function">ARRAY-TOTAL-SIZE</code></a> (because one of its dimensions is zero) are printed
 with the readable syntax <code class="computeroutput">#A(<em class="replaceable"><code>element-type</code></em> <em class="replaceable"><code>dimensions</code></em>
 <em class="replaceable"><code>contents</code></em>)</code>, unless the variable <a class="link" href="#pr-empty-arr-ansi" title="Variable CUSTOM:*PRINT-EMPTY-ARRAYS-ANSI*"><code class="varname">CUSTOM:*PRINT-EMPTY-ARRAYS-ANSI*</code></a> is
 non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, in which case the arrays are printed using the
 [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>]-prescribed syntax <code class="computeroutput"><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-12.html"><span class="data"><code class="literal">#<em class="replaceable"><code>rank</code></em>A</code></span></a> <em class="replaceable"><code>contents</code></em></code>
 which often loses the dimension information.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="pathprint"></a>22.6.1. Printing Pathnames
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-1-3-11.html">[sec_22-1-3-11]</a></h3></div></div></div><p>Pathnames are printed as follows: If <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-escapest.html" target="_top"><code class="varname">*PRINT-ESCAPE*</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>,
 only the namestring is printed; otherwise it is printed with the
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-14.html"><span class="data"><code class="literal">#P</code></span></a> syntax, as per the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] issue <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss276.html" target="_top">PRINT-READABLY-BEHAVIOR:CLARIFY</a>.
 But, if <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-readablyst.html" target="_top"><code class="varname">*PRINT-READABLY*</code></a> is true, we are in trouble as <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-14.html"><span class="data"><code class="literal">#P</code></span></a> is
 ambiguous (which is verboten when <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-readablyst.html" target="_top"><code class="varname">*PRINT-READABLY*</code></a> is true), while
 being mandated by the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>].
 Therefore, in this case, <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>'s behavior is determined by the value
 of <a class="link" href="#pathprint" title="22.6.1. Printing Pathnames sec_22-1-3-11"><code class="varname">CUSTOM:*PRINT-PATHNAMES-ANSI*</code></a>: when it is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, we print pathnames like this:
<code class="computeroutput"><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-18.html"><span class="data"><code class="literal">#-</code></span></a>CLISP <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-14.html"><span class="data"><code class="literal">#P</code></span></a>"..."
<a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-17.html"><span class="data"><code class="literal">#+</code></span></a>CLISP <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-13.html"><span class="data"><code class="literal">#S</code></span></a>(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_pathname.html" target="_top"><code class="classname">PATHNAME</code></a> ...)</code>.
Otherwise, when the variable <a class="link" href="#pathprint" title="22.6.1. Printing Pathnames sec_22-1-3-11"><code class="varname">CUSTOM:*PRINT-PATHNAMES-ANSI*</code></a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the
<a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-14.html"><span class="data"><code class="literal">#P</code></span></a> notation is used as per <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_1-5-1-4-1.html">[sec_1-5-1-4-1]</a>
<span class="quote">“<span class="quote">Resolution of Apparent Conflicts in Exceptional Situations</span>”</span>.
</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>The <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-13.html"><span class="data"><code class="literal">#S</code></span></a> notation for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_pathname.html" target="_top"><code class="classname">PATHNAME</code></a>s is used
  extensively in the [<span class="citation"><a class="link" href="#CLHS" title="Common Lisp HyperSpec">Common Lisp HyperSpec</a></span>] (see examples for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_pathname.html" target="_top"><code class="function">PATHNAME</code></a>,
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_pathnamep.html" target="_top"><code class="function">PATHNAMEP</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_parse-namestring.html" target="_top"><code class="function">PARSE-NAMESTRING</code></a> et al), but was decided against, see
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss260.html" target="_top">PATHNAME-PRINT-READ:SHARPSIGN-P</a>.</p></div><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>When both <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-readablyst.html" target="_top"><code class="varname">*PRINT-READABLY*</code></a> and <a class="link" href="#pathprint" title="22.6.1. Printing Pathnames sec_22-1-3-11"><code class="varname">CUSTOM:*PRINT-PATHNAMES-ANSI*</code></a> are
  non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and the namestring will be parsed to a dissimilar object
  (with the current value of <a class="link" href="#name-type-split" title="Name/type namestring split"><code class="varname">CUSTOM:*PARSE-NAMESTRING-DOT-FILE*</code></a>), an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> of type
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_print-not-readable.html" target="_top"><code class="classname">PRINT-NOT-READABLE</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.</p></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="clpp"></a>22.7. The Lisp Pretty Printer
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-2.html">[sec_22-2]</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#pp-dispatch">22.7.1. Pretty Print Dispatch Table   sec_22-2-1-4</a></span></dt></dl></div><p>The Lisp Pretty Printer implementation is <span class="strong"><strong>not</strong></span> perfect yet.
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_pprint-logical-block.html" target="_top"><code class="function">PPRINT-LOGICAL-BLOCK</code></a> does not respect <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-linesst.html" target="_top"><code class="varname">*PRINT-LINES*</code></a>.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="pp-dispatch"></a>22.7.1. Pretty Print Dispatch Table
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-2-1-4.html">[sec_22-2-1-4]</a></h3></div></div></div><p>A <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#pprint_dispatch_table">pprint dispatch table</a> is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_cons.html" target="_top"><code class="function">CONS</code></a>
 of a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-p_t-dispatchst.html" target="_top"><code class="varname">*PRINT-PPRINT-DISPATCH*</code></a> and an <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_a.html#association_list">association list</a> which maps
 types into priorities and print functions.
 Their use is strongly discouraged because of the performance issues:
 when <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-p_t-dispatchst.html" target="_top"><code class="varname">*PRINT-PPRINT-DISPATCH*</code></a> is non-trivial and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-prettyst.html" target="_top"><code class="varname">*PRINT-PRETTY*</code></a>
 is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, printing of every object requires a lookup in the table,
 which entails many calls to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_typep.html" target="_top"><code class="function">TYPEP</code></a> (which cannot be made fast
 enough).</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="print-formatted"></a>22.8. Formatted Output
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3.html">[sec_22-3]</a></h2></div><div><h3 class="subtitle">Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a></h3></div></div></div><p>The additional <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> instruction
 <strong class="first"><em class="firstterm"><code class="literal">~!</code><a id="format-bang" class="indexterm"></a></em></strong>
 is similar to <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-5-4.html"><code class="literal">~/</code></a>, but avoids putting a function name into a
 string, thus it is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_readcm_re_g-whitespace.html" target="_top"><code class="function">READ</code></a> in the current <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stpackagest.html" target="_top"><code class="varname">*PACKAGE*</code></a>, so, even if the
 function is not interned in the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-2.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP-USER</span>”</span></strong></a> package, you might not need
 to specify the package explicitly.
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> <em class="replaceable"><code>stream</code></em> "~arguments!" <em class="replaceable"><code>function</code></em> <em class="replaceable"><code>object</code></em>)</code> is
  equivalent to <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_funcall.html" target="_top"><code class="function">FUNCALL</code></a> <em class="replaceable"><code>function</code></em> <em class="replaceable"><code>stream</code></em> <em class="replaceable"><code>object</code></em>
  <em class="replaceable"><code>colon-modifier-p</code></em>
  <em class="replaceable"><code>atsign-modifier-p</code></em> <em class="replaceable"><code>arguments</code></em>)</code>.</p><p>The additional <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> instruction
 <strong class="first"><em class="firstterm"><code class="literal">~.</code><a id="format-dot" class="indexterm"></a></em></strong>
 is a kind of opposite to <code class="code">~&amp;</code>: It outputs a conditional
 newline, by calling the function <a class="link" href="#elastic-newline" title="21.11. Function EXT:ELASTIC-NEWLINE"><code class="function">EXT:ELASTIC-NEWLINE</code></a>.
 <code class="code">~<em class="replaceable"><code>n</code></em>.</code> outputs <em class="replaceable"><code>n-1</code></em> newlines
 followed by an <a class="link" href="#elastic-newline" title="21.11. Function EXT:ELASTIC-NEWLINE"><code class="function">EXT:ELASTIC-NEWLINE</code></a>. <code class="code">~0.</code> does nothing.</p><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-2-1.html"><code class="literal">~R</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-2-1.html"><code class="literal">~:R</code></a> can output only
 integers in the range <code class="code">|<em class="replaceable"><code>n</code></em>| &lt;
  <em class="replaceable"><code>10<sup>66</sup></code></em></code>.
 The output is in English, according to the American conventions, and
 these conventions are identical to the British conventions only in the
 range <code class="code">|<em class="replaceable"><code>n</code></em>| &lt;
  <em class="replaceable"><code>10<sup>9</sup></code></em></code>.</p><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-1-1.html"><code class="literal">~:@C</code></a> does not output the character itself, only the
 instruction how to type the character.</p><p>For <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-3-2.html"><code class="literal">~E</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-3-3.html"><code class="literal">~G</code></a>, the value of
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stread-de_oat-formatst.html" target="_top"><code class="varname">*READ-DEFAULT-FLOAT-FORMAT*</code></a> does not matter if <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-readablyst.html" target="_top"><code class="varname">*PRINT-READABLY*</code></a>
 is true.</p><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-6-1.html"><code class="literal">~T</code></a> can determine the current column of any
 built-in stream.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="write"></a>22.9. Functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">WRITE</code></a> &amp; <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_write-to-_nc-to-string.html" target="_top"><code class="function">WRITE-TO-STRING</code></a></h2></div></div></div><p>The functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">WRITE</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_write-to-_nc-to-string.html" target="_top"><code class="function">WRITE-TO-STRING</code></a> have an additional
 keyword argument <code class="constant">:CLOSURE</code> which is used to bind
 <a class="link" href="#pr-closure" title="Variable CUSTOM:*PRINT-CLOSURE*"><code class="varname">CUSTOM:*PRINT-CLOSURE*</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="print-unreadable-object"></a>22.10. Macro <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_print-unr_dable-object.html" target="_top"><code class="function">PRINT-UNREADABLE-OBJECT</code></a></h2></div></div></div><p><a id="pr-unreadable-ansi"></a><strong>Variable <a class="link" href="#pr-unreadable-ansi" title="Variable CUSTOM:*PRINT-UNREADABLE-ANSI*"><code class="varname">CUSTOM:*PRINT-UNREADABLE-ANSI*</code></a>. </strong>The macro <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_print-unr_dable-object.html" target="_top"><code class="function">PRINT-UNREADABLE-OBJECT</code></a>, when invoked without body forms,
 suppresses the trailing space if only the type is to be printed, and
 suppresses the leading space if only the identity is to be printed.  This
 behaviour can be turned off set setting the variable <a class="link" href="#pr-unreadable-ansi" title="Variable CUSTOM:*PRINT-UNREADABLE-ANSI*"><code class="varname">CUSTOM:*PRINT-UNREADABLE-ANSI*</code></a>
 to a non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> value: in this case, a trailing or leading space are output,
 as prescribed by [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>].</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="print-misc"></a>22.11. Miscellaneous Issues</h2></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-casest.html" target="_top"><code class="varname">*PRINT-CASE*</code></a> controls the output not only of symbols, but also
 of characters and some <span class="data"><code class="literal"><a href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-20.html">#&lt;</a>unreadable&gt;</code></span> objects.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platforms only.</span></span></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-prettyst.html" target="_top"><code class="varname">*PRINT-PRETTY*</code></a> is initially <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> but set to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>
 in <a class="link" href="#config-lisp"><code class="filename">config.lisp</code></a>.  This makes screen output prettier.
 </dd></dl></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-arrayst.html" target="_top"><code class="varname">*PRINT-ARRAY*</code></a> is initially set to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.</p></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="reader"></a>Chapter 23. Reader <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-23.html">[chap-23]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#rt-case">23.1. Effect of Readtable Case on the Lisp Reader   sec_23-1-2</a></span></dt><dt><span class="section"><a href="#recursive-p">23.2. The <em class="replaceable"><code>recursive-p</code></em> argument   sec_23-1-3-2</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="rt-case"></a>23.1. Effect of Readtable Case on the Lisp Reader
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_23-1-2.html">[sec_23-1-2]</a></h2></div></div></div><p>When the value of <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_readtable-case.html" target="_top"><code class="function">READTABLE-CASE</code></a>
 <em class="replaceable"><code>readtable</code></em>)</code> is
 <code class="constant">:INVERT</code>, it applies to the package name and the
 symbol name of a symbol separately (not to the entire token at once).
 An alternative to the use of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_readtable-case.html" target="_top"><code class="function">READTABLE-CASE</code></a> is the use of the
 <a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-SENSITIVE</code></a> option of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-package.html" target="_top"><code class="function">MAKE-PACKAGE</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defpackage.html" target="_top"><code class="function">DEFPACKAGE</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="recursive-p"></a>23.2. The <em class="replaceable"><code>recursive-p</code></em> argument
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_23-1-3-2.html">[sec_23-1-3-2]</a></h2></div></div></div><p>When non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> <em class="replaceable"><code>recursive-p</code></em> argument is passed to a top-level <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_readcm_re_g-whitespace.html" target="_top"><code class="function">READ</code></a>
 call, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.</p></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="system"></a>Chapter 24. System Construction
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-24.html">[chap-24]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#compilefile">24.1. Function <code class="function">COMPILE-FILE</code></a></span></dt><dd><dl><dt><span class="section"><a href="#compile-file-output">24.1.1. Output files</a></span></dt><dt><span class="section"><a href="#compile-file-return">24.1.2. Return values</a></span></dt></dl></dd><dt><span class="section"><a href="#compile-file-path">24.2. Function <code class="function">COMPILE-FILE-PATHNAME</code></a></span></dt><dt><span class="section"><a href="#require">24.3. Function <code class="function">REQUIRE</code></a></span></dt><dd><dl><dt><span class="section"><a href="#require-return">24.3.1. Return value</a></span></dt><dt><span class="section"><a href="#require-search">24.3.2. Additional <code class="function">LOAD</code> locations</a></span></dt><dt><span class="section"><a href="#module-providers">24.3.3. User variable <code class="varname">CUSTOM::*MODULE-PROVIDER-FUNCTIONS*</code></a></span></dt><dt><span class="section"><a href="#lib-files">24.3.4. Interaction with <code class="function">COMPILE-FILE</code></a></span></dt></dl></dd><dt><span class="section"><a href="#loadfile">24.4. Function <code class="function">LOAD</code></a></span></dt><dt><span class="section"><a href="#features">24.5. Variable <code class="varname">*FEATURES*</code></a></span></dt><dt><span class="section"><a href="#featurep">24.6. Function <code class="function">EXT:FEATUREP</code>   [CLRFI-1]</a></span></dt><dt><span class="section"><a href="#compiled-file-p">24.7. Function <code class="function">EXT:COMPILED-FILE-P</code>   [CLRFI-2]</a></span></dt></dl></div><p>The compiler can be called not only by the functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile.html" target="_top"><code class="function">COMPILE</code></a>,
 <a href="impnotes.html#compilefile" class="olink"><code class="function">COMPILE-FILE</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_disassemble.html" target="_top"><code class="function">DISASSEMBLE</code></a>, but also by the declaration
 <a class="link" href="#compile-decl" title="3.3.6. Declaration (COMPILE)"><code class="code">(COMPILE)</code></a>.</p><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="compilefile"></a>24.1. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile-file.html" target="_top"><code class="function">COMPILE-FILE</code></a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#compile-file-output">24.1.1. Output files</a></span></dt><dt><span class="section"><a href="#compile-file-return">24.1.2. Return values</a></span></dt></dl></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile-file.html" target="_top"><code class="function">COMPILE-FILE</code></a> compiles a file to a platform-independent
 <a href="impnotes.html#bytecode" class="olink">bytecode</a>:
</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile-file.html" target="_top"><code class="function">COMPILE-FILE</code></a> <em class="replaceable"><code>filename</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:OUTPUT-FILE</code> :LISTING <a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a>
                            ((<code class="constant">:WARNINGS</code> <a class="link" href="#compile-warn"><code class="varname">CUSTOM:*COMPILE-WARNINGS*</code></a>) <a class="link" href="#compile-warn"><code class="varname">CUSTOM:*COMPILE-WARNINGS*</code></a>)
                            ((<code class="constant">:VERBOSE</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stcompile_le-verbosest.html" target="_top"><code class="varname">*COMPILE-VERBOSE*</code></a>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stcompile_le-verbosest.html" target="_top"><code class="varname">*COMPILE-VERBOSE*</code></a>)
                            ((<code class="constant">:PRINT</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stcompile_le-verbosest.html" target="_top"><code class="varname">*COMPILE-PRINT*</code></a>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stcompile_le-verbosest.html" target="_top"><code class="varname">*COMPILE-PRINT*</code></a>))
</pre><div class="variablelist"><a id="compile-file-arguments"></a><p class="title"><strong>Options for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile-file.html" target="_top"><code class="function">COMPILE-FILE</code></a></strong></p><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>filename</code></em></span></dt><dd>the file to be compiled, should be a <a class="link" href="#path-des" title="Pathname Designators">pathname designator</a>.
 </dd><dt><span class="term"><code class="constant">:OUTPUT-FILE</code></span></dt><dd>should be <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> or a <a class="link" href="#path-des" title="Pathname Designators">pathname designator</a> or an
   <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_o.html#output">output</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>.  The default is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.</dd><dt><span class="term"><code class="constant">:LISTING</code></span></dt><dd>should be <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> or a <a class="link" href="#path-des" title="Pathname Designators">pathname designator</a> or an
   <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_o.html#output">output</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>.  The default is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</dd><dt><span class="term"><a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a></span></dt><dd>the <a class="link" href="#encoding" title="31.5. Encodings"><code class="classname">EXT:ENCODING</code></a> of the <em class="replaceable"><code>filename</code></em>.
</dd><dt><span class="term"><code class="constant">:WARNINGS</code></span></dt><dd>specifies whether warnings should also appear on the
   screen.</dd><dt><span class="term"><code class="constant">:VERBOSE</code></span></dt><dd>specifies whether error messages should also appear
   on the screen.</dd><dt><span class="term"><code class="constant">:PRINT</code></span></dt><dd>specifies whether an indication which forms are
   being compiled should appear on the screen.
</dd></dl></div><p>The variables <strong class="first"><em class="firstterm"><a class="link" href="#compile-warn"><code class="varname">CUSTOM:*COMPILE-WARNINGS*</code></a>
  <a id="compile-warn" class="indexterm"></a></em></strong>
 (initially set to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>), <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stcompile_le-verbosest.html" target="_top"><code class="varname">*COMPILE-VERBOSE*</code></a> (initially set to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>,
 affected by <code class="option"><a href="clisp.html#opt-verbose" class="olink">-v</a></code>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stcompile_le-verbosest.html" target="_top"><code class="varname">*COMPILE-PRINT*</code></a> (initially set to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>,
 affected by <code class="option"><a href="clisp.html#opt-verbose" class="olink">-v</a></code>) provide defaults for the <code class="constant">:WARNINGS</code>, <code class="constant">:VERBOSE</code>,
 <code class="constant">:PRINT</code> keyword arguments, respectively, and are bound by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile-file.html" target="_top"><code class="function">COMPILE-FILE</code></a>
 to the values of the arguments, i.e., these arguments are recursive.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="compile-file-output"></a>24.1.1. Output files</h3></div></div></div><p>For each input file (default file type: <code class="filename">#P".lisp"</code>)
 the following files are generated:
</p><div class="informaltable"><a id="compile-file-new-files-table"></a><table class="informaltable" border="1"><colgroup><col /><col /><col /><col align="left" /></colgroup><thead><tr><th align="center">File</th><th align="center">When</th><th align="center">Default file type</th><th align="left">Contents</th></tr></thead><tbody><tr><td align="center">output file</td><td align="center">only if <code class="constant">:OUTPUT-FILE</code> is not <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></td><td align="center"><code class="filename">#P".fas"</code></td><td align="left">can be loaded using the <a href="impnotes.html#loadfile" class="olink"><code class="function">LOAD</code></a> function</td></tr><tr><td align="center">auxiliary output file</td><td align="center">only if <code class="constant">:OUTPUT-FILE</code> is not <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></td><td align="center"><a class="link" href="#lib-files" title="24.3.4. Interaction with COMPILE-FILE"><code class="filename">#P".lib"</code></a></td><td align="left">used by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile-file.html" target="_top"><code class="function">COMPILE-FILE</code></a> when compiling a <a href="impnotes.html#require" class="olink"><code class="function">REQUIRE</code></a> form referring
    to the input file</td></tr><tr><td align="center">listing file</td><td align="center">only if <code class="constant">:LISTING</code> is not <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></td><td align="center"><code class="filename">#P".lis"</code></td><td align="left">disassembly of the output file</td></tr><tr><td align="center"><a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> output file</td><td align="center">only if <code class="constant">:OUTPUT-FILE</code> is not <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></td><td align="center"><code class="filename">#P".c"</code></td><td align="left"><a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>; this file is created only if the source contains
    <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> forms</td></tr></tbody></table></div><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="c-file-overwrite"></a>Warning</h3><p>If you have two files in the same
directory - <code class="filename">#P"foo.lisp"</code> and <code class="filename">#P"foo.c"</code>, and you
compile the first file with <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>, the second file will be
<span class="emphasis"><em>clobbered</em></span> if you have any <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> forms in
the first one!</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="compile-file-return"></a>24.1.2. Return values</h3></div></div></div><p>As per [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>], <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile-file.html" target="_top"><code class="function">COMPILE-FILE</code></a> returns 3 values:
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term">output-truename</span></dt><dd>the truename of the output <code class="filename">#P".fas"</code>, or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
  if the file could not be created, in which case the compilation is
  considered to have failed</dd><dt><span class="term">warnings-p</span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if no conditions of type <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_warning.html" target="_top"><code class="classname">WARNING</code></a>
  were detected during compilation, and the number of such conditions otherwise
</dd><dt><span class="term">failure-p</span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if no conditions of type <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_warning.html" target="_top"><code class="classname">WARNING</code></a>
  (other than <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_style-warning.html" target="_top"><code class="classname">STYLE-WARNING</code></a>) were detected during compilation,
  and the number of such conditions otherwise
</dd></dl></div><p>
Since <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> tends to be relatively garrulous with warnings
 (see, e.g., <a class="xref" href="#flocont" title="12.2.4.1. Rule of Float Precision Contagion sec_12-1-4-4">Section 12.2.4.1, “Rule of Float Precision Contagion   sec_12-1-4-4”</a>), the non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> tertiary return value
 (called <em class="replaceable"><code>failure-p</code></em> by the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>])
 does <span class="strong"><strong>not</strong></span> indicate a failure of compilation.
The correct way to check whether <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile-file.html" target="_top"><code class="function">COMPILE-FILE</code></a> has failed is the
 <span class="emphasis"><em>primary</em></span> return value.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="compile-file-path"></a>24.2. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile-file-pathname.html" target="_top"><code class="function">COMPILE-FILE-PATHNAME</code></a></h2></div></div></div><p>The default for the <code class="constant">:OUTPUT-FILE</code> argument is
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>, which means <code class="filename">#P".fas"</code>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="require"></a>24.3. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_providecm_require.html" target="_top"><code class="function">REQUIRE</code></a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#require-return">24.3.1. Return value</a></span></dt><dt><span class="section"><a href="#require-search">24.3.2. Additional <code class="function">LOAD</code> locations</a></span></dt><dt><span class="section"><a href="#module-providers">24.3.3. User variable <code class="varname">CUSTOM::*MODULE-PROVIDER-FUNCTIONS*</code></a></span></dt><dt><span class="section"><a href="#lib-files">24.3.4. Interaction with <code class="function">COMPILE-FILE</code></a></span></dt></dl></div><p>The function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_providecm_require.html" target="_top"><code class="function">REQUIRE</code></a> receives as the optional argument either
 a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_pathname.html" target="_top"><code class="classname">PATHNAME</code></a> or a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_pathname.html" target="_top"><code class="classname">PATHNAME</code></a>s: files to be <a href="impnotes.html#loadfile" class="olink"><code class="function">LOAD</code></a>ed
 if the required module is not already present.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="require-return"></a>24.3.1. Return value</h3></div></div></div><p>When the module is already present, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> is returned;
 otherwise returns the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_truename.html" target="_top"><code class="function">TRUENAME</code></a> which was loaded to satisfy the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_providecm_require.html" target="_top"><code class="function">REQUIRE</code></a>ment
 (or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> thereof iff the second argument is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>).</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="require-search"></a>24.3.2. Additional <a href="impnotes.html#loadfile" class="olink"><code class="function">LOAD</code></a> locations</h3></div></div></div><p>In addition to (and <span class="strong"><strong>before</strong></span>) <a href="impnotes.html#load-paths" class="olink"><code class="varname">CUSTOM:*LOAD-PATHS*</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_providecm_require.html" target="_top"><code class="function">REQUIRE</code></a> tries to
 find the file to <a href="impnotes.html#loadfile" class="olink"><code class="function">LOAD</code></a> in the following locations:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p class="simpara"><span class="plat-dep">Platform Dependent: <span class="plat-dep">Only in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> built <span class="strong"><strong>without</strong></span> configure flag <code class="option"><a href="impnotes.html#mod-dynload" class="olink">--without-dynamic-modules</a></code>.</span></span></p><p class="simpara">The system-wide external modules directory
    <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_merge-pathnames.html" target="_top"><code class="function">MERGE-PATHNAMES</code></a> "dynmod/" <a href="clisp.html#opt-libdir" class="olink"><code class="varname">CUSTOM:*LIB-DIRECTORY*</code></a>)</code>.</p></li><li class="listitem"><p class="simpara"><span class="plat-dep">Platform Dependent: <span class="plat-dep">Only in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> built <span class="strong"><strong>without</strong></span> configure flag <code class="option"><a href="impnotes.html#mod-dynload" class="olink">--without-dynamic-modules</a></code>.</span></span></p><p class="simpara">The user external modules directory <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_merge-pathnames.html" target="_top"><code class="function">MERGE-PATHNAMES</code></a>
     "dynmod/" <a href="clisp-link.html#opt-install" class="olink"><code class="varname">CUSTOM:*USER-LIB-DIRECTORY*</code></a>)</code>
    (when <a href="clisp-link.html#opt-install" class="olink"><code class="varname">CUSTOM:*USER-LIB-DIRECTORY*</code></a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>).</p></li><li class="listitem">When <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_providecm_require.html" target="_top"><code class="function">REQUIRE</code></a> was called while <a href="impnotes.html#loadfile" class="olink"><code class="function">LOAD</code></a>ing, the
    directory with the file being loaded (i.e., <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-pathname.html" target="_top"><code class="function">MAKE-PATHNAME</code></a>
     :name <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> :type <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> :defaults <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stload-pa_d-truenamest.html" target="_top"><code class="varname">*LOAD-TRUENAME*</code></a>)</code>).
</li></ul></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="module-providers"></a>24.3.3. User variable <a class="link" href="#module-providers" title="24.3.3. User variable CUSTOM::*MODULE-PROVIDER-FUNCTIONS*"><code class="varname">CUSTOM::*MODULE-PROVIDER-FUNCTIONS*</code></a></h3></div></div></div><p>When <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_providecm_require.html" target="_top"><code class="function">REQUIRE</code></a> is called without the second (pathname) argument,
 the elements of the <a class="link" href="#module-providers" title="24.3.3. User variable CUSTOM::*MODULE-PROVIDER-FUNCTIONS*"><code class="varname">CUSTOM::*MODULE-PROVIDER-FUNCTIONS*</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> are called one by one
 on the first (module name) argument until one of them returns non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
 If all of them return <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, <a href="impnotes.html#loadfile" class="olink"><code class="function">LOAD</code></a> is called as described
 <a class="link" href="#require-search" title="24.3.2. Additional LOAD locations">above</a>.</p><p>Initially the lisp is empty; <code class="code">(require "<span class="module"><a class="filename" href="#asdf" title="33.1. A System Definition Facility"><code class="filename">asdf</code></a></span>")</code>
 modifies it (<span class="plat-dep">Platform Dependent: <span class="plat-dep">if <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> was configured with the
 option <code class="option">--with-module=asdf</code></span></span>).</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="lib-files"></a>24.3.4. Interaction with <a href="impnotes.html#compilefile" class="olink"><code class="function">COMPILE-FILE</code></a></h3></div></div></div><p>At compile time, <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_providecm_require.html" target="_top"><code class="function">REQUIRE</code></a> <code class="filename">#P"foo"</code>)</code>
forms are treated specially: <a href="impnotes.html#load-paths" class="olink"><code class="varname">CUSTOM:*LOAD-PATHS*</code></a> is searched for
<code class="filename">#P"foo.lisp"</code> <span class="strong"><strong>and</strong></span> <code class="filename">#P"foo.lib"</code>.
If the latest such file is a <code class="filename">#P".lisp"</code>, it is compiled;
otherwise the <a class="link" href="#lib-files" title="24.3.4. Interaction with COMPILE-FILE"><code class="filename">#P".lib"</code></a> is loaded.
If neither is found, <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_providecm_require.html" target="_top"><code class="function">REQUIRE</code></a> <code class="filename">#P"foo"</code>)</code> is called.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="module-user-file-name-conflict"></a>Warning</h3><p>It is a <span class="strong"><strong>very</strong></span> bad
idea to name your files the same way as <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> modules
(whether <a class="link" href="#included-modules" title="32.2.9. Modules included in the source distribution">system-supplied</a>
or <a href="clisp-link.html#opt-install" class="olink">user-installed</a>)
because then <a href="impnotes.html#require" class="olink"><code class="function">REQUIRE</code></a> will use different files at compile
and execution times.</p></div><p>The <a class="link" href="#lib-files" title="24.3.4. Interaction with COMPILE-FILE"><code class="filename">#P".lib"</code></a> is a <span class="quote">“<span class="quote">header</span>”</span> file which contains the
constant, variable, inline and macro definitions necessary for
compilation of the files that <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_providecm_require.html" target="_top"><code class="function">REQUIRE</code></a> this file, but not the function
definitions and calls that are not necessary for that.
Thus it is <span class="strong"><strong>not</strong></span> necessary to either enclose <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_providecm_require.html" target="_top"><code class="function">REQUIRE</code></a> forms in
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_eval-when.html" target="_top"><code class="function">EVAL-WHEN</code></a> or to load the required files in the makefiles: if you have
two files, <code class="filename">#P"foo.lisp"</code> and <code class="filename">#P"bar.lisp"</code>, and the
latter requires the former, you can write in your <code class="filename">Makefile</code>:
</p><pre class="programlisting">
all: foo.fas bar.fas

foo.fas: foo.lisp
	clisp <code class="option"><a href="clisp.html#opt-compile" class="olink">-c</a></code> foo

bar.fas: bar.lisp foo.fas
	clisp <code class="option"><a href="clisp.html#opt-compile" class="olink">-c</a></code> bar
</pre><p>
instead of the more cumbersome (and slower, since <a class="link" href="#lib-files" title="24.3.4. Interaction with COMPILE-FILE"><code class="filename">#P".lib"</code></a>s are
usually smaller and load faster that <code class="filename">#P".fas"</code>s):
</p><pre class="programlisting">
bar.fas: bar.lisp foo.fas
        <span class="command"><strong><a href="clisp.html#clisp" class="olink">clisp</a></strong></span> <code class="option"><a href="clisp.html#opt-init" class="olink">-i</a></code> foo <code class="option"><a href="clisp.html#opt-compile" class="olink">-c</a></code> bar
</pre><p>
Thus, you do not need to <code class="code">(<a href="impnotes.html#loadfile" class="olink"><code class="function">LOAD</code></a> <code class="filename">#P"foo"</code>)</code> in order
to <code class="code">(<a href="impnotes.html#compilefile" class="olink"><code class="function">COMPILE-FILE</code></a> <code class="filename">#P"bar.lisp"</code>)</code>.
If memory is tight, and if <code class="filename">#P"foo.lisp"</code> contains only a few inline
functions, macros, constants or variables, this is a space and time
saver.  If <code class="filename">#P"foo.lisp"</code> does a lot of initializations or side effects
when being loaded, this is important as well.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="loadfile"></a>24.4. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_load.html" target="_top"><code class="function">LOAD</code></a></h2></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_load.html" target="_top"><code class="function">LOAD</code></a> accepts four additional keyword arguments <code class="constant">:ECHO</code>,
 <code class="constant">:COMPILING</code>, <code class="constant">:EXTRA-FILE-TYPES</code>, and <code class="constant">:OBSOLETE-ACTION</code>.</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_load.html" target="_top"><code class="function">LOAD</code></a> <em class="replaceable"><code>filename</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> ((<code class="constant">:VERBOSE</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stload-pr_ad-verbosest.html" target="_top"><code class="varname">*LOAD-VERBOSE*</code></a>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stload-pr_ad-verbosest.html" target="_top"><code class="varname">*LOAD-VERBOSE*</code></a>)
                    ((<code class="constant">:PRINT</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stload-pr_ad-verbosest.html" target="_top"><code class="varname">*LOAD-PRINT*</code></a>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stload-pr_ad-verbosest.html" target="_top"><code class="varname">*LOAD-PRINT*</code></a>)
                    ((<code class="constant">:ECHO</code> <a href="impnotes.html#load-echo" class="olink"><code class="varname">CUSTOM:*LOAD-ECHO*</code></a>) <a href="impnotes.html#load-echo" class="olink"><code class="varname">CUSTOM:*LOAD-ECHO*</code></a>) <code class="constant">:IF-DOES-NOT-EXIST</code>
                    ((<code class="constant">:COMPILING</code> <a href="impnotes.html#load-comp" class="olink"><code class="varname">CUSTOM:*LOAD-COMPILING*</code></a>) <a href="impnotes.html#load-comp" class="olink"><code class="varname">CUSTOM:*LOAD-COMPILING*</code></a>) <code class="constant">:EXTRA-FILE-TYPES</code>
                    ((<code class="constant">:OBSOLETE-ACTION</code> <a class="link" href="#load-obs"><code class="varname">CUSTOM:*LOAD-OBSOLETE-ACTION*</code></a>) <a class="link" href="#load-obs"><code class="varname">CUSTOM:*LOAD-OBSOLETE-ACTION*</code></a>)
                    (ignore-pathname-defaults nil))
</pre><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:VERBOSE</code></span></dt><dd>causes <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_load.html" target="_top"><code class="function">LOAD</code></a> to emit a short message that a file is
    being loaded.  The default is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stload-pr_ad-verbosest.html" target="_top"><code class="varname">*LOAD-VERBOSE*</code></a>, which is initially
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>, but can be changed by the <code class="option"><a href="clisp.html#opt-verbose" class="olink">-v</a></code> option.
 </dd><dt><span class="term"><code class="constant">:PRINT</code></span></dt><dd>causes <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_load.html" target="_top"><code class="function">LOAD</code></a> to print the value of each form.  The
    default is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stload-pr_ad-verbosest.html" target="_top"><code class="varname">*LOAD-PRINT*</code></a>, which is initially <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, but can be
    changed by the <code class="option"><a href="clisp.html#opt-verbose" class="olink">-v</a></code> option.</dd><dt><span class="term"><code class="constant">:ECHO</code></span></dt><dd>causes the input from the file to be echoed to
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-OUTPUT*</code></a> (normally to the screen).  Should there be an
    error in the file, you can see at one glance where it is.
    The default is <strong class="first"><em class="firstterm"><a href="impnotes.html#load-echo" class="olink"><code class="varname">CUSTOM:*LOAD-ECHO*</code></a>
     <a id="load-echo" class="indexterm"></a></em></strong>,
     which is initially <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, but can be changed by the <code class="option"><a href="clisp.html#opt-verbose" class="olink">-v</a></code> option.
 </dd><dt><span class="term"><code class="constant">:COMPILING</code></span></dt><dd>causes each form read to be compiled on the fly.
    The compiled code is executed at once and - in contrast to
    <a href="impnotes.html#compilefile" class="olink"><code class="function">COMPILE-FILE</code></a> - not written to a file.
    The default is <strong class="first"><em class="firstterm"><a href="impnotes.html#load-comp" class="olink"><code class="varname">CUSTOM:*LOAD-COMPILING*</code></a>
     <a id="load-comp" class="indexterm"></a></em></strong>,
     which is initially <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, but can be changed by the <code class="option"><a href="clisp.html#opt-load-comp" class="olink">-C</a></code> option.
 </dd><dt><span class="term"><code class="constant">:EXTRA-FILE-TYPES</code></span></dt><dd><p class="simpara">Specifies the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of additional file types
    considered for loading, in addition to <strong class="first"><em class="firstterm"><a class="link" href="#source-types"><code class="varname">CUSTOM:*SOURCE-FILE-TYPES*</code></a>
     <a id="source-types" class="indexterm"></a></em></strong>
    (which is initially <span class="data"><code class="literal">("lisp" "lsp" "cl")</code></span>)
    and <strong class="first"><em class="firstterm"><a class="link" href="#compiled-types"><code class="varname">CUSTOM:*COMPILED-FILE-TYPES*</code></a>
      <a id="compiled-types" class="indexterm"></a></em></strong>
    (which is initially <span class="data"><code class="literal">("fas")</code></span>).
   </p><p class="simpara">When <em class="replaceable"><code>filename</code></em> does not specify a unique file
    (e.g., <em class="replaceable"><code>filename</code></em> is <code class="filename">#P"foo"</code> and both <code class="filename">#P"foo.lisp"</code>
    and <code class="filename">#P"foo.fas"</code> are found in the
    <a href="impnotes.html#load-paths" class="olink"><code class="varname">CUSTOM:*LOAD-PATHS*</code></a>), then the <span class="emphasis"><em>newest</em></span> file is loaded.
 </p></dd><dt><span class="term"><code class="constant">:OBSOLETE-ACTION</code></span></dt><dd><p>Specifies the action to take when loading a
    <code class="filename">#P".fas"</code> with a different <a href="impnotes.html#bytecode" class="olink">bytecode</a> version from the one
    supported by this <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> version.  The possible actions are
    </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:DELETE</code></span></dt><dd>delete the <code class="filename">#P".fas"</code> and proceed as with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
     </dd><dt><span class="term"><code class="constant">:ERROR</code></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a> an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>
     </dd><dt><span class="term"><code class="constant">:COMPILE</code></span></dt><dd>recompile the source file (if found in <a href="impnotes.html#load-paths" class="olink"><code class="varname">CUSTOM:*LOAD-PATHS*</code></a>)
        and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_load.html" target="_top"><code class="function">LOAD</code></a> the result</dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> (default)</span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_warn.html" target="_top"><code class="function">WARN</code></a> and <a class="link" href="#load-paths" title="Variable CUSTOM:*LOAD-PATHS*">look
         for another matching file</a>
    </dd></dl></div><p>
    If no file can be loaded and <code class="constant">:IF-DOES-NOT-EXIST</code> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.
    The default is <strong class="first"><em class="firstterm"><a class="link" href="#load-obs"><code class="varname">CUSTOM:*LOAD-OBSOLETE-ACTION*</code></a>
     <a id="load-obs" class="indexterm"></a></em></strong>,
    which is initially <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</p></dd><dt><span class="term"><code class="constant">:IGNORE-PATHNAME-DEFAULTS</code></span></dt><dd>Do not merge <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdefault_e-defaultsst.html" target="_top"><code class="varname">*DEFAULT-PATHNAME-DEFAULTS*</code></a> to the
   argument using <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_merge-pathnames.html" target="_top"><code class="function">MERGE-PATHNAMES</code></a> (as required by [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>]) and rely
   on <a href="impnotes.html#load-paths" class="olink"><code class="varname">CUSTOM:*LOAD-PATHS*</code></a> instead.</dd></dl></div><p>The variables <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stload-pr_ad-verbosest.html" target="_top"><code class="varname">*LOAD-VERBOSE*</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stload-pr_ad-verbosest.html" target="_top"><code class="varname">*LOAD-PRINT*</code></a>,
<a class="link" href="#load-obs"><code class="varname">CUSTOM:*LOAD-OBSOLETE-ACTION*</code></a>, <a href="impnotes.html#load-comp" class="olink"><code class="varname">CUSTOM:*LOAD-COMPILING*</code></a>, and <a href="impnotes.html#load-echo" class="olink"><code class="varname">CUSTOM:*LOAD-ECHO*</code></a> are bound by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_load.html" target="_top"><code class="function">LOAD</code></a> when it
receives a corresponding keyword argument (<code class="constant">:VERBOSE</code>, <code class="constant">:PRINT</code>,
<code class="constant">:OBSOLETE-ACTION</code>, <code class="constant">:COMPILING</code>, and <code class="constant">:ECHO</code>), i.e., these arguments
are recursive, just like the arguments <code class="constant">:WARNINGS</code>, <code class="constant">:VERBOSE</code>, and
<code class="constant">:PRINT</code> for <a href="impnotes.html#compilefile" class="olink"><code class="function">COMPILE-FILE</code></a>.</p><p>When evaluation of a read form <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>, three <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_restart.html" target="_top"><code class="classname">RESTART</code></a>s are
 available:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">SKIP</code></span></dt><dd>Skip this form and read the next one.
  </dd><dt><span class="term"><code class="literal">RETRY</code></span></dt><dd>Try to evaluate this form again.
  </dd><dt><span class="term"><code class="literal">STOP</code></span></dt><dd>Stop loading the file.
</dd></dl></div><p>On success, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_load.html" target="_top"><code class="function">LOAD</code></a> returns the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_truename.html" target="_top"><code class="function">TRUENAME</code></a> of the file which it loaded,
 or the <em class="replaceable"><code>filename</code></em> argument if it is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> but not a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_file-stream.html" target="_top"><code class="classname">FILE-STREAM</code></a>.
</p><p><a id="load-paths"></a><strong>Variable <a href="impnotes.html#load-paths" class="olink"><code class="varname">CUSTOM:*LOAD-PATHS*</code></a>. </strong>The variable <a href="impnotes.html#load-paths" class="olink"><code class="varname">CUSTOM:*LOAD-PATHS*</code></a> contains a list of directories where the
 files are looked for - in addition to the specified or current
 directory - by <a href="impnotes.html#loadfile" class="olink"><code class="function">LOAD</code></a>, <a href="impnotes.html#require" class="olink"><code class="function">REQUIRE</code></a>, <a href="impnotes.html#compilefile" class="olink"><code class="function">COMPILE-FILE</code></a> and
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_load-logi_translations.html" target="_top"><code class="function">LOAD-LOGICAL-PATHNAME-TRANSLATIONS</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="features"></a>24.5. Variable <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stfeaturesst.html" target="_top"><code class="varname">*FEATURES*</code></a></h2></div></div></div><p>The variable <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stfeaturesst.html" target="_top"><code class="varname">*FEATURES*</code></a> initially contains the following symbols
</p><div class="variablelist"><a id="features-table"></a><p class="title"><strong>Default <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stfeaturesst.html" target="_top"><code class="varname">*FEATURES*</code></a></strong></p><dl class="variablelist"><dt><span class="term"><code class="constant">:CLISP</code></span></dt><dd>the name of this implementation
</dd><dt><span class="term"><code class="constant">:ANSI-CL</code></span></dt><dd><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#purports_to_conform">purports to
    conform</a> to [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>]</dd><dt><span class="term"><code class="constant">:COMMON-LISP</code></span></dt><dd>required by [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>]</dd><dt><span class="term"><code class="constant">:INTERPRETER</code></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eval.html" target="_top"><code class="function">EVAL</code></a> is implemented</dd><dt><span class="term"><code class="constant">:COMPILER</code></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile.html" target="_top"><code class="function">COMPILE</code></a> and <a href="impnotes.html#compilefile" class="olink"><code class="function">COMPILE-FILE</code></a> are implemented
</dd><dt><span class="term"><code class="constant">:SOCKETS</code></span></dt><dd>see <a class="xref" href="#socket" title="32.4. Socket Streams">Section 32.4, “Socket Streams”</a>
</dd><dt><span class="term"><code class="constant">:MT</code></span></dt><dd>see <a class="xref" href="#mt" title="32.5. Multiple Threads of Execution">Section 32.5, “Multiple Threads of Execution”</a>
</dd><dt><span class="term"><code class="constant">:GENERIC-STREAMS</code></span></dt><dd>see <a class="xref" href="#gstream" title="31.6. Generic streams">Section 31.6, “Generic streams”</a>
</dd><dt><span class="term"><code class="constant">:LOGICAL-PATHNAMES</code></span></dt><dd><a class="link" href="#log-path" title="19.4. Logical Pathnames sec_19-3">Logical Pathnames</a>
   are implemented</dd><dt><span class="term"><code class="constant">:FFI</code></span></dt><dd>if a foreign function interface
   (see <a class="xref" href="#dffi" title="32.3. The Foreign Function Call Facility">Section 32.3, “The Foreign Function Call Facility”</a>) is supported
   (<span class="plat-dep">Platform Dependent: <span class="plat-dep">Many <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>
    platforms only</span></span>)</dd><dt><span class="term"><code class="constant">:GETTEXT</code></span></dt><dd>if internationalization (see <a class="xref" href="#i18n" title="31.4. Internationalization of CLISP">Section 31.4, “Internationalization of <span class="command"><strong>CLISP</strong></span>”</a>)
   using the <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/gettext/" target="_top">gettext</a> package is supported
   (<span class="plat-dep">Platform Dependent: <span class="plat-dep">most <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> platforms
    only</span></span>)</dd><dt><span class="term"><code class="constant">:UNICODE</code></span></dt><dd>if <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> (ISO 10646) characters are supported
   (see <a class="xref" href="#encoding" title="31.5. Encodings">Section 31.5, “Encodings”</a>)</dd><dt><span class="term"><code class="constant">:LOOP</code></span></dt><dd><span class="quote">“<span class="quote">extended</span>”</span> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_loop.html" target="_top"><code class="function">LOOP</code></a> form is implemented
</dd><dt><span class="term"><code class="constant">:CLOS</code></span></dt><dd><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> is implemented</dd><dt><span class="term"><code class="constant">:MOP</code></span></dt><dd><a class="link" href="#mop-chap" title="Chapter 29. Meta-Object Protocol">Meta-Object Protocol</a> is implemented</dd><dt><span class="term"><code class="constant">:WORD-SIZE=64</code></span></dt><dd>if <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> was built for a 64-bit CPU.  This could
   be useful on platforms with 64-bit CPUs which have a 32-bit mode
   emulation (e.g., <span class="platform">i386</span> is
   emulated on <span class="platform">x86_64</span>
   and <span class="platform">ia64</span>) so that the user can
   decide which ABI library to load dynamically using <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>.
</dd><dt><span class="term"><code class="constant">:WIN32</code></span></dt><dd>if <em class="replaceable"><code>hardware</code></em> = PC (clone) and <em class="replaceable"><code>operating system</code></em> = <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>
  (Windows 95/98/Me/NT/2000/XP)</dd><dt><span class="term"><code class="constant">:PC386</code></span></dt><dd>if <em class="replaceable"><code>hardware</code></em> = PC (clone).  It can be used as an
   indicator for the mainstream hardware characteristics (such as the
   existence of a graphics card with a non-graphics text mode,
   or the presence of a keyboard with arrows and
   <span class="keysym">Insert</span>/<span class="keysym">Delete</span> keys,
   or an ISA/VLB/PCI bus) or software characteristics (such as the
   <span class="keycap"><strong>Control</strong></span>+<span class="keycap"><strong>Alternate</strong></span>+<span class="keysym">Delete</span> keyboard
   combination).</dd><dt><span class="term"><code class="constant">:UNIX</code></span></dt><dd>if <em class="replaceable"><code>operating system</code></em> = <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> (in this case the <em class="replaceable"><code>hardware</code></em> is irrelevant!)
</dd><dt><span class="term"><code class="constant">:BEOS</code></span></dt><dd>if <em class="replaceable"><code>operating system</code></em> = <a class="ulink" href="https://www.haiku-os.org/" target="_top"><span class="platform">BeOS</span></a> (in that case <code class="constant">:UNIX</code> is also present)
</dd><dt><span class="term"><code class="constant">:CYGWIN</code></span></dt><dd>if <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> is using the <a class="ulink" href="http://cygwin.com/" target="_top"><span class="platform">Cygwin</span></a> <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> compatibility
  layer on top of <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> (in that case <code class="constant">:UNIX</code> is also present)
</dd><dt><span class="term"><code class="constant">:MACOS</code></span></dt><dd>if <em class="replaceable"><code>operating system</code></em> = <a class="ulink" href="http://www.apple.com/macosx/" target="_top"><span class="platform">Mac OS X</span></a> (in that case <code class="constant">:UNIX</code> is also present)
</dd></dl></div><p>Each <a href="impnotes.html#modules" class="olink">module</a> should add the appropriate keyword, e.g.,
 <a class="link" href="#syscalls" title="33.2. System Calls"><code class="constant">:SYSCALLS</code></a>,
 <a class="link" href="#dir-key" title="33.8. Directory Access"><code class="constant">:DIRKEY</code></a>,
 <a class="link" href="#regexp-mod" title="33.4. POSIX Regular Expressions"><code class="constant">:REGEXP</code></a>,
 <a class="link" href="#pcre" title="33.15. Perl Compatible Regular Expressions"><code class="constant">:PCRE</code></a>, etc.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="featurep"></a>24.6. Function <code class="function">EXT:FEATUREP</code>
  <a class="ulink" href="http://clrfi.alu.org/clrfi/clrfi-1-featurep" target="_top">[CLRFI-1]</a></h2></div></div></div><p><code class="code">(EXT:FEATUREP <em class="replaceable"><code>form</code></em>)</code> provides run-time access to
 the read-time conditionals <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-17.html"><span class="data"><code class="literal">#+</code></span></a> and <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-18.html"><span class="data"><code class="literal">#-</code></span></a>.
 <em class="replaceable"><code>form</code></em> is a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_24-1-2-1.html">feature exression</a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="compiled-file-p"></a>24.7. Function <a class="link" href="#compiled-file-p" title="24.7. Function EXT:COMPILED-FILE-P [CLRFI-2]"><code class="function">EXT:COMPILED-FILE-P</code></a>
  <a class="ulink" href="http://clrfi.alu.org/clrfi/clrfi-2-compiled-file-p" target="_top">[CLRFI-2]</a></h2></div></div></div><p><code class="code">(<a class="link" href="#compiled-file-p" title="24.7. Function EXT:COMPILED-FILE-P [CLRFI-2]"><code class="function">EXT:COMPILED-FILE-P</code></a> <em class="replaceable"><code>filename</code></em>)</code> returns non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
 when the file <em class="replaceable"><code>filename</code></em> exists, is readable, and appears to be a
 <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>-compiled <code class="filename">#P".fas"</code> file compatible with the currently used
 <a href="impnotes.html#bytecode" class="olink">bytecode</a> format.</p><p>System definition facilities (such as <a class="ulink" href="http://common-lisp.net/project/asdf/" target="_top"><code class="function">asdf</code></a> or <a class="ulink" href="http://www.cliki.net/mk-defsystem" target="_top"><code class="function">defsystem</code></a>) can
 use it to determine whether the file needs to be recompiled.</p></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="environment"></a>Chapter 25. Environment
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-25.html">[chap-25]</a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#repl">25.1. Top Level Loop   sec_25-1-1</a></span></dt><dd><dl><dt><span class="section"><a href="#user-commands">25.1.1. User-defined Commands</a></span></dt></dl></dd><dt><span class="section"><a href="#debugger">25.2. Debugging Utilities   sec_25-1-2</a></span></dt><dd><dl><dt><span class="section"><a href="#disassemble">25.2.1. Function <code class="function">DISASSEMBLE</code></a></span></dt><dt><span class="section"><a href="#uncompile">25.2.2. Function <code class="function">EXT:UNCOMPILE</code></a></span></dt><dt><span class="section"><a href="#show-stack">25.2.3. Function <code class="function">EXT:SHOW-STACK</code></a></span></dt><dt><span class="section"><a href="#documentation">25.2.4. Function <code class="function">DOCUMENTATION</code></a></span></dt><dt><span class="section"><a href="#describe">25.2.5. Function <code class="function">DESCRIBE</code></a></span></dt><dt><span class="section"><a href="#trace">25.2.6. Macro <code class="function">TRACE</code></a></span></dt><dt><span class="section"><a href="#inspect">25.2.7. Function <code class="function">INSPECT</code></a></span></dt><dt><span class="section"><a href="#time">25.2.8. Macro <code class="function">TIME</code></a></span></dt><dt><span class="section"><a href="#ed">25.2.9. Function <code class="function">ED</code></a></span></dt><dt><span class="section"><a href="#apropos">25.2.10. Functions <code class="function">APROPOS</code> &amp; <code class="function">APROPOS-LIST</code></a></span></dt><dt><span class="section"><a href="#dribble">25.2.11. Function <code class="function">DRIBBLE</code></a></span></dt><dd><dl><dt><span class="section"><a href="#dribble-script">25.2.11.1. Scripting and <code class="function">DRIBBLE</code></a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="#environment-enq">25.3. Environment Inquiry   sec_25-1-3</a></span></dt><dd><dl><dt><span class="section"><a href="#room">25.3.1. Function <code class="function">ROOM</code></a></span></dt><dt><span class="section"><a href="#gc-sect">25.3.2. Function <code class="function">EXT:GC</code>
   </a></span></dt><dt><span class="section"><a href="#machine">25.3.3. Machine</a></span></dt><dt><span class="section"><a href="#version">25.3.4. Function <code class="function">LISP-IMPLEMENTATION-VERSION</code></a></span></dt><dt><span class="section"><a href="#argv">25.3.5. Function <code class="function">EXT:ARGV</code></a></span></dt></dl></dd><dt><span class="section"><a href="#clock">25.4. Time sec_25-1-4</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="repl"></a>25.1. Top Level Loop
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-1.html">[sec_25-1-1]</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#user-commands">25.1.1. User-defined Commands</a></span></dt></dl></div><p>The debugger may be invoked through the functions
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_invoke-debugger.html" target="_top"><code class="function">INVOKE-DEBUGGER</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_break.html" target="_top"><code class="function">BREAK</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_error.html" target="_top"><code class="function">ERROR</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_cerror.html" target="_top"><code class="function">CERROR</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_warn.html" target="_top"><code class="function">WARN</code></a>.
 The stepper is invoked through the macro <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_step.html" target="_top"><code class="function">STEP</code></a>.
 Debugger and stepper execute subordinate <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-1.html">read-eval-print loop</a>
 (called <strong class="first"><em class="firstterm">break loops</em></strong>)
 which are similar to the main <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-1.html">read-eval-print loop</a> except for the
 <a class="link" href="#prompt" title="31.9. The Prompt">prompt</a> and the set of available commands.
 Commands must be typed literally, in any case,
 without surrounding quotes or <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-1-4-7.html">whitespace</a>.
 Each command has a keyword abbreviation,
 indicated in the second column.</p><div class="table"><a id="debugger-main-deb-step"></a><p class="title"><strong>Table 25.1. Commands common to the main loop, the debugger and the stepper</strong></p><div class="table-contents"><table class="table" summary="Commands common to the main loop, the debugger and the stepper" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">command</th><th align="center">abbreviation</th><th align="center">operation</th></tr></thead><tbody><tr><td align="center"><a href="impnotes.html#debugger-main-deb-step" class="olink"><span class="command"><strong>help</strong></span></a></td><td align="center"><span class="command"><strong>:h</strong></span></td><td align="center">print a list of available commands</td></tr><tr><td align="center"><span class="command"><strong>LocalSymbols</strong></span></td><td align="center"><span class="command"><strong>:ls</strong></span></td><td align="center">print the list of
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>s <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_intern.html" target="_top"><code class="function">INTERN</code></a>ed in a given <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_package.html" target="_top"><code class="classname">PACKAGE</code></a>.</td></tr></tbody></table></div></div><br class="table-break" /><div class="table"><a id="debugger-deb-step"></a><p class="title"><strong>Table 25.2. Commands common to the debugger and the stepper</strong></p><div class="table-contents"><table class="table" summary="Commands common to the debugger and the stepper" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">command</th><th align="center">abbreviation</th><th align="center">operation</th></tr></thead><tbody><tr><td align="center"><span class="command"><strong>Abort</strong></span></td><td align="center"><span class="command"><strong>:a</strong></span></td><td align="center">abort to the next most recent <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-1.html">read-eval-print loop</a></td></tr><tr><td align="center"><span class="command"><strong>Unwind</strong></span></td><td align="center"><span class="command"><strong>:uw</strong></span></td><td align="center">abort to the next most recent <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-1.html">read-eval-print loop</a></td></tr><tr><td align="center"><span class="command"><strong>Quit</strong></span></td><td align="center"><span class="command"><strong>:q</strong></span></td><td align="center">quit to the top <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-1.html">read-eval-print loop</a></td></tr></tbody></table></div></div><br class="table-break" /><p>The stack is organized into frames and other stack elements.
 Usually every invocation of an interpreted function and every
 evaluation of an interpreted form corresponds to one stack frame.
 Special forms such as <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET*</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_unwind-protect.html" target="_top"><code class="function">UNWIND-PROTECT</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_catch.html" target="_top"><code class="function">CATCH</code></a>
 produce special kinds of stack frames.</p><p><a id="cur-frame"></a>In a break loop there is a
 <strong class="first"><em class="firstterm"><a class="link" href="#cur-frame">current stack frame</a></em></strong>, which is initially the most recent
 stack frame but can be moved using the debugger
 commands <span class="command"><strong>Up</strong></span> and <span class="command"><strong>Down</strong></span>.</p><p>Evaluation of forms in a break loop occurs in the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a> of the
 <a class="link" href="#cur-frame">current stack frame</a> and <span class="emphasis"><em>at the same time</em></span> in the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-2.html">dynamic environment</a>
 of the debugger's caller.  This means that to inspect or modify a
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-1-1.html">lexical variable</a> all you have to do is to move the <a class="link" href="#cur-frame">current stack frame</a> to be just
 below the frame that corresponds to the form or the function call that
 binds that variable.</p><p><a id="stack-mode"></a><strong>Stack Printing Mode. </strong>There is a current <strong class="first"><em class="firstterm">stack mode</em></strong> which defines
 in how much detail the stack is shown by the stack-related debugger
 commands (<a class="link" href="#backtrace"><span class="command"><strong>backtrace</strong></span></a> et al):</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">All the stack elements are considered.
    This mode works fine for debugging compiled functions.</li><li class="listitem">All the frames are considered.</li><li class="listitem">Only lexical frames (frames that correspond to special
    forms that modify the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a>) are considered.</li><li class="listitem">Only <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eval.html" target="_top"><code class="function">EVAL</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_apply.html" target="_top"><code class="function">APPLY</code></a> frames are considered.
    Every evaluation of a form in the interpreter corresponds to an
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eval.html" target="_top"><code class="function">EVAL</code></a> frame.  This is the default.</li><li class="listitem">Only <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_apply.html" target="_top"><code class="function">APPLY</code></a> frames are considered.
    Every invocation of an interpreted function corresponds to one
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_apply.html" target="_top"><code class="function">APPLY</code></a> frame.</li></ol></div><div class="table"><a id="debugger-deb-step-1"></a><p class="title"><strong>Table 25.3. Commands common to the debugger and the stepper</strong></p><div class="table-contents"><table class="table" summary="Commands common to the debugger and the stepper" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">command</th><th align="center">abbreviation</th><th align="center">operation</th></tr></thead><tbody><tr><td align="center"><span class="command"><strong>Error</strong></span></td><td align="center"><span class="command"><strong>:e</strong></span></td><td align="center">print the last error object.</td></tr><tr><td align="center"><span class="command"><strong>Inspect</strong></span></td><td align="center"><span class="command"><strong>:i</strong></span></td><td align="center"><a class="link" href="#inspect" title="25.2.7. Function INSPECT"><code class="function">INSPECT</code></a> the last error object.</td></tr><tr><td align="center"><span class="command"><strong>Where</strong></span></td><td align="center"><span class="command"><strong>:w</strong></span></td><td align="center">show the <a class="link" href="#cur-frame">current stack frame</a>.</td></tr><tr><td align="center"><span class="command"><strong>Up</strong></span></td><td align="center"><span class="command"><strong>:u</strong></span></td><td align="center">go up one frame, i.e., to the caller if in mode-5</td></tr><tr><td align="center"><span class="command"><strong>Down</strong></span></td><td align="center"><span class="command"><strong>:d</strong></span></td><td align="center">do down one frame, i.e., to the callee if in mode-5</td></tr><tr><td align="center"><span class="command"><strong>Top</strong></span></td><td align="center"><span class="command"><strong>:t</strong></span></td><td align="center">go to top frame, i.e., to the top-level form if in mode-4
 </td></tr><tr><td align="center"><span class="command"><strong>Bottom</strong></span></td><td align="center"><span class="command"><strong>:b</strong></span></td><td align="center">go to bottom (most recent) frame, i.e., most probably to the
   form or function that caused the debugger to be entered.</td></tr><tr><td align="center"><span class="command"><strong>Mode</strong></span> <a class="link" href="#stack-mode" title="Stack Printing Mode"><em class="replaceable"><code>stack-mode</code></em></a></td><td align="center"><span class="command"><strong>:m</strong></span> <a class="link" href="#stack-mode" title="Stack Printing Mode"><em class="replaceable"><code>stack-mode</code></em></a></td><td align="center">set the current stack printing mode</td></tr><tr><td align="center"><a id="frame-limit"></a><span class="command"><strong>Frame-limit</strong></span> <em class="replaceable"><code>l</code></em></td><td align="center"><span class="command"><strong>:fl</strong></span></td><td align="center">set the <a class="link" href="#frame-limit"><em class="replaceable"><code>frame-limit</code></em></a>: this many frames will be printed
   by <a class="link" href="#backtrace"><span class="command"><strong>backtrace</strong></span></a> at most.</td></tr><tr><td align="center"><a id="backtrace"></a><a class="link" href="#backtrace"><span class="command"><strong>backtrace</strong></span></a> [<a class="link" href="#stack-mode" title="Stack Printing Mode"><em class="replaceable"><code>stack-mode</code></em></a> [<em class="replaceable"><code>l</code></em>]]</td><td align="center"><span class="command"><strong>:bt</strong></span> [<a class="link" href="#stack-mode" title="Stack Printing Mode"><em class="replaceable"><code>stack-mode</code></em></a> [<em class="replaceable"><code>l</code></em>]]</td><td align="center">list the stack in the given <a class="link" href="#stack-mode" title="Stack Printing Mode"><em class="replaceable"><code>stack-mode</code></em></a>, bottom frame first,
  top frame last; at most <em class="replaceable"><code>l</code></em> frames are printed;
  calls <a class="link" href="#show-stack" title="25.2.3. Function EXT:SHOW-STACK"><code class="function">EXT:SHOW-STACK</code></a>.</td></tr></tbody></table></div></div><br class="table-break" /><p>If the <a class="link" href="#cur-frame">current stack frame</a> is an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eval.html" target="_top"><code class="function">EVAL</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_apply.html" target="_top"><code class="function">APPLY</code></a> frame, the
  following commands are available as well:</p><div class="table"><a id="debugger-eval-apply"></a><p class="title"><strong>Table 25.4. Commands specific to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eval.html" target="_top"><code class="function">EVAL</code></a>/<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_apply.html" target="_top"><code class="function">APPLY</code></a></strong></p><div class="table-contents"><table class="table" summary="Commands specific to EVAL/APPLY" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">command</th><th align="center">abbreviation</th><th align="center">operation</th></tr></thead><tbody><tr><td align="center"><span class="command"><strong>Break+</strong></span></td><td align="center"><span class="command"><strong>:br+</strong></span></td><td align="center">set a breakpoint in the current frame.  When the corresponding
  form or function will be left, the debugger will be entered again, with
  the variable <a class="link" href="#trace-val"><code class="varname">EXT:*TRACE-VALUES*</code></a> containing a list of its values.</td></tr><tr><td align="center"><span class="command"><strong>Break-</strong></span></td><td align="center"><span class="command"><strong>:br-</strong></span></td><td align="center">remove a breakpoint from the current frame.</td></tr><tr><td align="center"><span class="command"><strong>Redo</strong></span></td><td align="center"><span class="command"><strong>:rd</strong></span></td><td align="center">re-evaluate the corresponding form or function call. This
  command can be used to restart parts of a computation without
  aborting it entirely.</td></tr><tr><td align="center"><span class="command"><strong>Return</strong></span> <em class="replaceable"><code>value</code></em></td><td align="center"><span class="command"><strong>:rt</strong></span> <em class="replaceable"><code>value</code></em></td><td align="center">leave the current frame, returning the given value.</td></tr></tbody></table></div></div><br class="table-break" /><div class="table"><a id="debugger-deb"></a><p class="title"><strong>Table 25.5. Commands specific to the debugger</strong></p><div class="table-contents"><table class="table" summary="Commands specific to the debugger" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">command</th><th align="center">abbreviation</th><th align="center">operation</th></tr></thead><tbody><tr><td align="center"><span class="command"><strong>Continue</strong></span></td><td align="center"><span class="command"><strong>:c</strong></span></td><td align="center">continue evaluation of the program.</td></tr></tbody></table></div></div><br class="table-break" /><div class="table"><a id="debugger-step"></a><p class="title"><strong>Table 25.6. Commands specific to the stepper</strong></p><div class="table-contents"><table class="table" summary="Commands specific to the stepper" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">command</th><th align="center">abbreviation</th><th align="center">operation</th></tr></thead><tbody><tr><td align="center"><span class="command"><strong>Step</strong></span></td><td align="center"><span class="command"><strong>:s</strong></span></td><td align="center">step into a form: evaluate this form in single step mode
   </td></tr><tr><td align="center"><span class="command"><strong>Next</strong></span></td><td align="center"><span class="command"><strong>:n</strong></span></td><td align="center">step over a form: evaluate this form at once
   </td></tr><tr><td align="center"><span class="command"><strong>Over</strong></span></td><td align="center"><span class="command"><strong>:o</strong></span></td><td align="center">step over this level: evaluate at once up to the next return
   </td></tr><tr><td align="center"><span class="command"><strong>Continue</strong></span></td><td align="center"><span class="command"><strong>:c</strong></span></td><td align="center">switch off single step mode, continue evaluation
   </td></tr></tbody></table></div></div><br class="table-break" /><p>The stepper is usually used like this: If some form returns a
 strange value or results in an error, call <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_step.html" target="_top"><code class="function">STEP</code></a>
 <em class="replaceable"><code>form</code></em>)</code> and navigate using the
 commands <span class="command"><strong>Step</strong></span> and <span class="command"><strong>Next</strong></span> until you
 reach the form you regard as responsible.  If you are too fast (execute
 <span class="command"><strong>Next</strong></span> once and get the error), there is no way back;
 you have to restart the entire stepper session.  If you are too slow
 (stepped into a function or a form which certainly is OK), a couple of
 <span class="command"><strong>Next</strong></span> commands or one <span class="command"><strong>Over</strong></span> command
 will help.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="user-commands"></a>25.1.1. User-defined Commands</h3></div></div></div><p>You can set <strong class="first"><em class="firstterm"><a class="link" href="#user-commands" title="25.1.1. User-defined Commands"><code class="varname">CUSTOM:*USER-COMMANDS*</code></a></em></strong> to a list of
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a>s, each returning a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>
 of <strong class="first"><em class="firstterm">bindings</em></strong>, i.e., either a
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a></span></dt><dd>the help string printed by <a href="impnotes.html#debugger-main-deb-step" class="olink"><span class="command"><strong>help</strong></span></a> in addition to the
  standard <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> help</dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_cons.html" target="_top"><code class="classname">CONS</code></a> <span class="data"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>
   . <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a>)</code></span></span></dt><dd>the actual binding: when the user types the string,
   the function is called on the remainder of the string, i.e., the part
   of the string after the command.</dd></dl></div><p> E.g.,
</p><pre class="programlisting">
(setq <a class="link" href="#user-commands" title="25.1.1. User-defined Commands"><code class="varname">CUSTOM:*USER-COMMANDS*</code></a>
      (list (lambda () (list (format nil "~2%User-defined commands:")))
            (lambda ()
              (flet ((panic (argline)
                       (format t "don't panic~@[ because of ~A~], ~D~%"
                               (and (plusp (length argline)) argline)
                               (random 42))))
                (list (format nil "~%panic   :p    hit the panic button!")
                      (cons "panic" #'panic)
                      (cons ":p" #'panic))))
            (lambda ()
              (let ((curses #("ouch" "yuk" "bletch")))
                (flet ((swear (argline)
                         (format t "~A: ~A!~%" argline
                                 (aref curses (random (length curses))))))
                  (list (format nil "~%swear   :e    curse")
                        (cons "swear" #'swear)
                        (cons ":e" #'swear)))))))
</pre></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="debugger"></a>25.2. Debugging Utilities
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-2.html">[sec_25-1-2]</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#disassemble">25.2.1. Function <code class="function">DISASSEMBLE</code></a></span></dt><dt><span class="section"><a href="#uncompile">25.2.2. Function <code class="function">EXT:UNCOMPILE</code></a></span></dt><dt><span class="section"><a href="#show-stack">25.2.3. Function <code class="function">EXT:SHOW-STACK</code></a></span></dt><dt><span class="section"><a href="#documentation">25.2.4. Function <code class="function">DOCUMENTATION</code></a></span></dt><dt><span class="section"><a href="#describe">25.2.5. Function <code class="function">DESCRIBE</code></a></span></dt><dt><span class="section"><a href="#trace">25.2.6. Macro <code class="function">TRACE</code></a></span></dt><dt><span class="section"><a href="#inspect">25.2.7. Function <code class="function">INSPECT</code></a></span></dt><dt><span class="section"><a href="#time">25.2.8. Macro <code class="function">TIME</code></a></span></dt><dt><span class="section"><a href="#ed">25.2.9. Function <code class="function">ED</code></a></span></dt><dt><span class="section"><a href="#apropos">25.2.10. Functions <code class="function">APROPOS</code> &amp; <code class="function">APROPOS-LIST</code></a></span></dt><dt><span class="section"><a href="#dribble">25.2.11. Function <code class="function">DRIBBLE</code></a></span></dt><dd><dl><dt><span class="section"><a href="#dribble-script">25.2.11.1. Scripting and <code class="function">DRIBBLE</code></a></span></dt></dl></dd></dl></div><div class="list-of-examples"><p><strong>List of Examples</strong></p><dl><dt>25.1. <a href="#trace-call-id">Identifying Individual Calls in <code class="function">TRACE</code></a></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="disassemble"></a>25.2.1. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_disassemble.html" target="_top"><code class="function">DISASSEMBLE</code></a></h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> platform only.</span></span></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_disassemble.html" target="_top"><code class="function">DISASSEMBLE</code></a> can disassemble to machine code,
    provided that <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://sources.redhat.com/gdb/" target="_top"><span class="command"><strong>gdb</strong></span></a> is present. In that case the argument may be a
   <code class="classname">EXT:SYSTEM-FUNCTION</code>, a <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a>, a
   special operator handler, a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a> denoting one of these, an
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> (address), or a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="uncompile"></a>25.2.2. Function <a class="link" href="#uncompile" title="25.2.2. Function EXT:UNCOMPILE"><code class="function">EXT:UNCOMPILE</code></a></h3></div></div></div><p>The function <a class="link" href="#uncompile" title="25.2.2. Function EXT:UNCOMPILE"><code class="function">EXT:UNCOMPILE</code></a> does the converse of
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile.html" target="_top"><code class="function">COMPILE</code></a>: <code class="code">(<a class="link" href="#uncompile" title="25.2.2. Function EXT:UNCOMPILE"><code class="function">EXT:UNCOMPILE</code></a> <em class="replaceable"><code>function</code></em>)</code> reverts a compiled
 <em class="replaceable"><code>function</code></em> (name), that has been entered or loaded in the same session
 and then compiled, back to its interpreted form.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="show-stack"></a>25.2.3. Function <a class="link" href="#show-stack" title="25.2.3. Function EXT:SHOW-STACK"><code class="function">EXT:SHOW-STACK</code></a></h3></div></div></div><p>The function <a class="link" href="#show-stack" title="25.2.3. Function EXT:SHOW-STACK"><code class="function">EXT:SHOW-STACK</code></a> is called by the <a class="link" href="#backtrace"><span class="command"><strong>backtrace</strong></span></a> command.</p><p>It prints to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-OUTPUT*</code></a> and accepts 3 optional
arguments:</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><a class="link" href="#stack-mode" title="Stack Printing Mode"><em class="replaceable"><code>stack-mode</code></em></a></li><li class="listitem"><a class="link" href="#frame-limit"><em class="replaceable"><code>frame-limit</code></em></a></li><li class="listitem"><em class="replaceable"><code>start-frame</code></em></li></ol></div><p>It can used to find out what all the threads are up to:
</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_loop.html" target="_top"><code class="function">LOOP</code></a> :with out = <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-OUTPUT*</code></a> :for <em class="replaceable"><code>thread</code></em> :in (<a class="link" href="#list-threads"><code class="function">MT:LIST-THREADS</code></a>) :do
   (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> out "===~A===~;" <em class="replaceable"><code>thread</code></em>)
   (<a class="link" href="#thread-interrupt"><code class="function">MT:THREAD-INTERRUPT</code></a> <em class="replaceable"><code>thread</code></em> :function
     (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_lambda.html" target="_top"><code class="function">LAMBDA</code></a> () (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET</code></a> ((<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-OUTPUT*</code></a> out)) (<a class="link" href="#show-stack" title="25.2.3. Function EXT:SHOW-STACK"><code class="function">EXT:SHOW-STACK</code></a> 1 3)))))
</pre><p>
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="documentation"></a>25.2.4. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_doc_umentationcp.html" target="_top"><code class="function">DOCUMENTATION</code></a></h3></div></div></div><p>No on-line documentation is available for the system functions
 (yet), but see <a class="xref" href="#describe" title="25.2.5. Function DESCRIBE">Section 25.2.5, “Function <code class="function">DESCRIBE</code>”</a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="describe"></a>25.2.5. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_describe.html" target="_top"><code class="function">DESCRIBE</code></a></h3></div></div></div><p>When <a class="link" href="#browse-url" title="31.11.11. Function EXT:BROWSE-URL"><code class="varname">CUSTOM:*BROWSER*</code></a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, and <a href="impnotes.html#clhs-root" class="olink"><code class="function">CUSTOM:CLHS-ROOT</code></a> returns a valid URL,
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_describe.html" target="_top"><code class="function">DESCRIBE</code></a> on a standard <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> symbol will point your web browser to the
 appropriate [<span class="citation"><a class="link" href="#CLHS" title="Common Lisp HyperSpec">Common Lisp HyperSpec</a></span>] page.</p><p>Also, when <a class="link" href="#browse-url" title="31.11.11. Function EXT:BROWSE-URL"><code class="varname">CUSTOM:*BROWSER*</code></a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, and <a href="impnotes.html#impnotes-root" class="olink"><code class="function">CUSTOM:IMPNOTES-ROOT</code></a> returns a
 valid URL, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_describe.html" target="_top"><code class="function">DESCRIBE</code></a> on symbols and packages documented in these
 implementation notes will point your web browser to the appropriate
 page.</p><p>To do this, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_describe.html" target="_top"><code class="function">DESCRIBE</code></a> will retrieve the appropriate tables from
 <a href="impnotes.html#clhs-root" class="olink"><code class="function">CUSTOM:CLHS-ROOT</code></a> and <a href="impnotes.html#impnotes-root" class="olink"><code class="function">CUSTOM:IMPNOTES-ROOT</code></a> on the first relevant invocation.
 These operations are logged to <a class="link" href="#http-log-stream" title="31.11.10. Variable CUSTOM:*HTTP-LOG-STREAM*"><code class="varname">CUSTOM:*HTTP-LOG-STREAM*</code></a>.</p><p><a id="clhs-root"></a><strong>Function <a href="impnotes.html#clhs-root" class="olink"><code class="function">CUSTOM:CLHS-ROOT</code></a>. </strong>Function <a href="impnotes.html#clhs-root" class="olink"><code class="function">CUSTOM:CLHS-ROOT</code></a> is defined in <a class="link" href="#config-lisp"><code class="filename">config.lisp</code></a>.  By default it
 looks at <code class="code">(<a class="link" href="#getenv" title="32.8. Operating System Environment"><code class="function">EXT:GETENV</code></a> "CLHSROOT")</code> and <a class="link" href="#clhs-root" title="Function CUSTOM:CLHS-ROOT"><code class="varname">CUSTOM:*CLHS-ROOT-DEFAULT*</code></a>,
 but you may redefine it in <a class="link" href="#config-lisp"><code class="filename">config.lisp</code></a> or <a href="clisp.html#opt-norc" class="olink">RC file</a>.
 The return value should be a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> terminated with a <code class="filename">"/"</code>,
 e.g., <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/" target="_top">http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/</a> or <code class="filename">/usr/doc/HyperSpec/</code>.
 If the return value is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the feature is completely disabled.
 <a class="link" href="#clhs-root" title="Function CUSTOM:CLHS-ROOT"><code class="varname">CUSTOM:*CLHS-ROOT-DEFAULT*</code></a> is initialized in <a class="link" href="#config-lisp"><code class="filename">config.lisp</code></a> based on
 the <code class="option">--hyperspec</code> passed to the top-level <a class="ulink" href="http://www.gnu.org/software/autoconf/" target="_top"><span class="command"><strong>configure</strong></span></a>
 script when <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> was built.</p><p><a id="impnotes-root"></a><strong>Function <a href="impnotes.html#impnotes-root" class="olink"><code class="function">CUSTOM:IMPNOTES-ROOT</code></a>. </strong>Function <a href="impnotes.html#impnotes-root" class="olink"><code class="function">CUSTOM:IMPNOTES-ROOT</code></a> is defined in <a class="link" href="#config-lisp"><code class="filename">config.lisp</code></a>.  By default it
 looks at <code class="code">(<a class="link" href="#getenv" title="32.8. Operating System Environment"><code class="function">EXT:GETENV</code></a> "IMPNOTES")</code> and <a class="link" href="#impnotes-root" title="Function CUSTOM:IMPNOTES-ROOT"><code class="varname">CUSTOM:*IMPNOTES-ROOT-DEFAULT*</code></a>,
 but you may redefine it in <a class="link" href="#config-lisp"><code class="filename">config.lisp</code></a> or <a href="clisp.html#opt-norc" class="olink">RC file</a>.
 The return value should be a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> terminated with a <code class="filename">"/"</code>,
 e.g., <a class="ulink" href="http://clisp.org/impnotes/" target="_top">http://clisp.org/impnotes/</a>, or the path to
 the monolithic page, e.g., <a class="ulink" href="http://clisp.org/impnotes.html" target="_top">http://clisp.org/impnotes.html</a>
 or <code class="filename">/usr/doc/clisp/impnotes.html</code>.
 If the return value is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the feature is completely disabled.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="trace"></a>25.2.6. Macro <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_tracecm_untrace.html" target="_top"><code class="function">TRACE</code></a></h3></div></div></div><div class="list-of-examples"><p><strong>List of Examples</strong></p><dl><dt>25.1. <a href="#trace-call-id">Identifying Individual Calls in <code class="function">TRACE</code></a></dt></dl></div><p><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_tracecm_untrace.html" target="_top"><code class="function">TRACE</code></a> <em class="replaceable"><code>function-name</code></em> ...)</code> makes the
 functions <em class="replaceable"><code>function-name</code></em>, ... traced.  Each <em class="replaceable"><code>function-name</code></em> should be either
 a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_f.html#function_name">function name</a> or a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> <code class="code">(<em class="replaceable"><code>function-name</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
 <code class="constant">:SUPPRESS-IF</code> <code class="constant">:MAX-DEPTH</code>
 <code class="constant">:STEP-IF</code> <code class="constant">:BINDINGS</code>
 <code class="constant">:PRE</code> <code class="constant">:POST</code>
 <code class="constant">:PRE-BREAK-IF</code> <code class="constant">:POST-BREAK-IF</code>
 <code class="constant">:PRE-PRINT</code> <code class="constant">:POST-PRINT</code>
 <code class="constant">:PRINT</code>)</code>, where</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:SUPPRESS-IF</code> <em class="replaceable"><code>form</code></em></span></dt><dd>no trace output as long as <em class="replaceable"><code>form</code></em> is true
  </dd><dt><span class="term"><code class="constant">:MAX-DEPTH</code> <em class="replaceable"><code>form</code></em></span></dt><dd>no trace output as long as <code class="code">(&gt;
  *trace-level* <em class="replaceable"><code>form</code></em>)</code>. This is useful for tracing functions that
  are use by the tracer itself, such as <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_print-object.html" target="_top"><code class="function">PRINT-OBJECT</code></a>, or otherwise when
  tracing would lead to an infinite recursion.
  </dd><dt><span class="term"><code class="constant">:STEP-IF</code> <em class="replaceable"><code>form</code></em></span></dt><dd>invokes the stepper as soon as <em class="replaceable"><code>form</code></em> is true
  </dd><dt><span class="term"><code class="constant">:BINDINGS</code>
   ((<em class="replaceable"><code>variable</code></em> <em class="replaceable"><code>form</code></em>)...)</span></dt><dd>binds <em class="replaceable"><code>variable</code></em>s to the result of evaluation of
    <em class="replaceable"><code>form</code></em>s around evaluation of all of the following forms
  </dd><dt><span class="term"><code class="constant">:PRE</code> <em class="replaceable"><code>form</code></em></span></dt><dd>evaluates <em class="replaceable"><code>form</code></em> before calling the function
  </dd><dt><span class="term"><code class="constant">:POST</code> <em class="replaceable"><code>form</code></em></span></dt><dd>evaluates <em class="replaceable"><code>form</code></em> after return from the function
  </dd><dt><span class="term"><code class="constant">:PRE-BREAK-IF</code> <em class="replaceable"><code>form</code></em></span></dt><dd>goes into the break loop before calling the
   function if <em class="replaceable"><code>form</code></em> is true</dd><dt><span class="term"><code class="constant">:POST-BREAK-IF</code> <em class="replaceable"><code>form</code></em></span></dt><dd>goes into the break loop after return from the
   function if <em class="replaceable"><code>form</code></em> is true</dd><dt><span class="term"><code class="constant">:PRE-PRINT</code> <em class="replaceable"><code>form</code></em></span></dt><dd>prints the values of <em class="replaceable"><code>form</code></em> before calling the
   function</dd><dt><span class="term"><code class="constant">:POST-PRINT</code> <em class="replaceable"><code>form</code></em></span></dt><dd>prints the values of <em class="replaceable"><code>form</code></em> after return from the
   function</dd><dt><span class="term"><code class="constant">:PRINT</code> <em class="replaceable"><code>form</code></em></span></dt><dd>prints the values of <em class="replaceable"><code>form</code></em> both before calling
   and after return from the function</dd></dl></div><p>In all these forms you can access the following variables:
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="varname">EXT:*TRACE-FUNCTION*</code></span></dt><dd>the traced function itself
  </dd><dt><span class="term"><code class="varname">EXT:*TRACE-ARGS*</code></span></dt><dd>the arguments to the function
  </dd><dt><span class="term"><code class="varname">EXT:*TRACE-FORM*</code></span></dt><dd>the function/macro call as form
  </dd><dt><a id="trace-val"></a><span class="term"><a class="link" href="#trace-val"><code class="varname">EXT:*TRACE-VALUES*</code></a></span></dt><dd>after return from the function: the list of return
  values from the function call</dd></dl></div><p>
and you can leave the function call with specified values by using
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_return.html" target="_top"><code class="function">RETURN</code></a>.</p><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_tracecm_untrace.html" target="_top"><code class="function">TRACE</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_tracecm_untrace.html" target="_top"><code class="function">UNTRACE</code></a> are also applicable to functions
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <em class="replaceable"><code>symbol</code></em>)</code> and to macros, but not to
 locally defined functions and macros.</p><div class="simplesect"><div class="titlepage"><div><div><h4 class="title"><a id="trace-out"></a>Trace output</h4></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_tracecm_untrace.html" target="_top"><code class="function">TRACE</code></a> prints this line before evaluating the form:
<code class="computeroutput"><em class="replaceable"><code>trace level</code></em>. Trace: <em class="replaceable"><code>form</code></em></code>
and after evaluating the form it prints:
<code class="computeroutput"><em class="replaceable"><code>trace level</code></em>. Trace: <em class="replaceable"><code>function-name</code></em> ==&gt; <em class="replaceable"><code>result</code></em></code>
where <span class="quote">“<span class="quote">trace level</span>”</span> is the total nesting level.
</p></div><div class="simplesect"><div class="titlepage"><div><div><h4 class="title"><a id="trace-indent"></a>Variable <a class="link" href="#trace-indent" title="Variable CUSTOM:*TRACE-INDENT*"><code class="varname">CUSTOM:*TRACE-INDENT*</code></a></h4></div></div></div><p>If you want the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_tracecm_untrace.html" target="_top"><code class="function">TRACE</code></a> level to be indicated by the indentation
in addition to the printed numbers, set <a class="link" href="#trace-indent" title="Variable CUSTOM:*TRACE-INDENT*"><code class="varname">CUSTOM:*TRACE-INDENT*</code></a> to non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
Initially it is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> since many nested traced calls will easily
exhaust the available line length.</p></div><div class="simplesect"><div class="titlepage"><div><div><h4 class="title"><a id="trace-eg"></a>Examples</h4></div></div></div><div class="example"><a id="trace-call-id"></a><p class="title"><strong>Example 25.1. Identifying Individual Calls in <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_tracecm_untrace.html" target="_top"><code class="function">TRACE</code></a></strong></p><div class="example-contents"><p>Suppose the trace level above is not enough for you to identify
 individual calls.  You can give each call a unique id and print it:
</p><pre class="programlisting">
(defun f0 (x)
  (cond ((zerop x) 1)
        ((zerop (random 2)) (* x (f0 (1- x))))
        (t (* x (f1 (1- x))))))
⇒ <code class="computeroutput">F0</code>
(defun f1 (x)
  (cond ((zerop x) 1)
        ((zerop (random 2)) (* x (f0 (1- x))))
        (t (* x (f1 (1- x))))))
⇒ <code class="computeroutput">F1</code>
(defvar *f0-call-count* 0)
⇒ <code class="computeroutput">*F0-CALL-COUNT*</code>
(defvar *id0*)
⇒ <code class="computeroutput">*ID0*</code>
(defvar *cc0*)
⇒ <code class="computeroutput">*CC0*</code>
(defvar *f1-call-count* 0)
⇒ <code class="computeroutput">*F1-CALL-COUNT*</code>
(defvar *id1*)
⇒ <code class="computeroutput">*ID1*</code>
(defvar *cc1*)
⇒ <code class="computeroutput">*CC1*</code>
(trace (f0 :bindings ((*cc0* (incf *f0-call-count*))
                      (*id0* (gensym "F0-")))
           :pre-print (list 'enter *id0* *cc0*)
           :post-print (list 'exit *id0* *cc0*))
       (f1 :bindings ((*cc1* (incf *f1-call-count*))
                      (*id1* (gensym "F1-")))
           :pre-print (list 'enter *id1* *cc1*)
           :post-print (list 'exit *id1* *cc1*)))
;; Tracing function F0.
;; Tracing function F1.
⇒ <code class="computeroutput">(F0 F1)</code>
(f0 10)
1. Trace: (F0 '10)
(ENTER #:F0-2926 1)
2. Trace: (F1 '9)
(ENTER #:F1-2927 1)
3. Trace: (F0 '8)
(ENTER #:F0-2928 2)
4. Trace: (F1 '7)
(ENTER #:F1-2929 2)
5. Trace: (F1 '6)
(ENTER #:F1-2930 3)
6. Trace: (F1 '5)
(ENTER #:F1-2931 4)
7. Trace: (F1 '4)
(ENTER #:F1-2932 5)
8. Trace: (F0 '3)
(ENTER #:F0-2933 3)
9. Trace: (F1 '2)
(ENTER #:F1-2934 6)
10. Trace: (F0 '1)
(ENTER #:F0-2935 4)
11. Trace: (F1 '0)
(ENTER #:F1-2936 7)
(EXIT #:F1-2936 7)
11. Trace: F1 ==&gt; 1
(EXIT #:F0-2935 4)
10. Trace: F0 ==&gt; 1
(EXIT #:F1-2934 6)
9. Trace: F1 ==&gt; 2
(EXIT #:F0-2933 3)
8. Trace: F0 ==&gt; 6
(EXIT #:F1-2932 5)
7. Trace: F1 ==&gt; 24
(EXIT #:F1-2931 4)
6. Trace: F1 ==&gt; 120
(EXIT #:F1-2930 3)
5. Trace: F1 ==&gt; 720
(EXIT #:F1-2929 2)
4. Trace: F1 ==&gt; 5040
(EXIT #:F0-2928 2)
3. Trace: F0 ==&gt; 40320
(EXIT #:F1-2927 1)
2. Trace: F1 ==&gt; 362880
(EXIT #:F0-2926 1)
1. Trace: F0 ==&gt; 3628800
⇒ <code class="computeroutput">3628800</code>
*f0-call-count*
⇒ <code class="computeroutput">4</code>
*f1-call-count*
⇒ <code class="computeroutput">7</code></pre></div></div><br class="example-break" /></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="inspect"></a>25.2.7. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_inspect.html" target="_top"><code class="function">INSPECT</code></a></h3></div></div></div><p>The function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_inspect.html" target="_top"><code class="function">INSPECT</code></a> accepts a keyword argument
 <code class="constant">:FRONTEND</code>, which specifies the way <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> will
 interact with the user, and defaults
 to <code class="varname">CUSTOM:*INSPECT-FRONTEND*</code>.
</p><div class="variablelist"><p class="title"><strong>Available <code class="constant">:FRONTEND</code>s for
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_inspect.html" target="_top"><code class="function">INSPECT</code></a> in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a></strong></p><dl class="variablelist"><dt><span class="term"><code class="constant">:TTY</code></span></dt><dd>The interaction is conducted via the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stterminal-iost.html" target="_top"><code class="varname">*TERMINAL-IO*</code></a>
    stream.  Please use the <a href="impnotes.html#debugger-main-deb-step" class="olink"><span class="command"><strong>help</strong></span></a> command to get the list of all
    available commands.</dd><dt><span class="term"><code class="constant">:HTTP</code></span></dt><dd><p class="simpara">A window in your Web browser (specified by the
    <a class="link" href="#browse-url" title="31.11.11. Function EXT:BROWSE-URL"><code class="constant">:BROWSER</code></a> keyword argument) is opened and it is controlled by
    <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> via a <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-STREAM</code></a>, using the <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> protocol.
    You should be able to use all the standard browser features.</p><p class="simpara">Since <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> is not multitasking at this time, you will not
    be able to do anything else during an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_inspect.html" target="_top"><code class="function">INSPECT</code></a> session.  Please click on
    the <strong class="userinput"><code>quit</code></strong> link to terminate the session.</p><p class="simpara">Please be aware though, that once you terminate an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_inspect.html" target="_top"><code class="function">INSPECT</code></a>
    session, all links in all <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_inspect.html" target="_top"><code class="function">INSPECT</code></a> windows in your browser will become
    obsolete and using them in a new <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_inspect.html" target="_top"><code class="function">INSPECT</code></a> session will result in
    unpredictable behavior.</p></dd></dl></div><p>The function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_inspect.html" target="_top"><code class="function">INSPECT</code></a> also accepts a keyword argument <a class="link" href="#browse-url" title="31.11.11. Function EXT:BROWSE-URL"><code class="constant">:BROWSER</code></a>,
 which specifies the browser used by the <code class="constant">:HTTP</code>
 front-end and defaults to <code class="varname">CUSTOM:*INSPECT-BROWSER*</code>.</p><p>The function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_inspect.html" target="_top"><code class="function">INSPECT</code></a> binds some
 <a class="link" href="#clpp" title="22.7. The Lisp Pretty Printer sec_22-2">pretty-printer</a> variables:
 </p><div class="informaltable"><a id="inspect-vars"></a><table class="informaltable" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="left">Variable</th><th align="left">Bound to</th></tr></thead><tbody><tr><td align="left"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-l_int-lengthst.html" target="_top"><code class="varname">*PRINT-LENGTH*</code></a></td><td align="left"><code class="varname">CUSTOM:*INSPECT-PRINT-LENGTH*</code></td></tr><tr><td align="left"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-l_int-lengthst.html" target="_top"><code class="varname">*PRINT-LEVEL*</code></a></td><td align="left"><code class="varname">CUSTOM:*INSPECT-PRINT-LEVEL*</code></td></tr><tr><td align="left"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-linesst.html" target="_top"><code class="varname">*PRINT-LINES*</code></a></td><td align="left"><code class="varname">CUSTOM:*INSPECT-PRINT-LINES*</code></td></tr></tbody></table></div><p>User variable
 <strong class="first"><em class="firstterm"><code class="varname">CUSTOM:*INSPECT-LENGTH*</code>
  <a id="inspect-length" class="indexterm"></a></em></strong>
 specifies the number of sequence elements or slots printed in detail
 when a sequence or a structure or a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> object is inspected.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="time"></a>25.2.8. Macro <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_time.html" target="_top"><code class="function">TIME</code></a></h3></div></div></div><p>The timing data printed by the macro <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_time.html" target="_top"><code class="function">TIME</code></a> includes:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">the real time (<span class="quote">“<span class="quote">wall</span>”</span> time,
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_get-internal-real-time.html" target="_top"><code class="function">GET-INTERNAL-REAL-TIME</code></a>),</li><li class="listitem">the run time (processor time for this process,
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_get-internal-run-time.html" target="_top"><code class="function">GET-INTERNAL-RUN-TIME</code></a>),</li><li class="listitem">the number of bytes allocated, and</li><li class="listitem">the number of <a href="impnotes.html#gc" class="olink">garbage-collect</a>ions performed, if any.
</li></ul></div><p>The macro <strong class="first"><em class="firstterm"><a class="link" href="#time" title="25.2.8. Macro TIME"><code class="function">EXT:TIMES</code></a>
  <a id="times" class="indexterm"></a></em></strong> (mnemonic:
 <span class="quote">“<span class="quote"><span class="emphasis"><em>TIME</em></span> and <span class="emphasis"><em>S</em></span>pace</span>”</span>)
 is like the macro <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_time.html" target="_top"><code class="function">TIME</code></a>: <code class="code">(<a class="link" href="#time" title="25.2.8. Macro TIME"><code class="function">EXT:TIMES</code></a> <em class="replaceable"><code>form</code></em>)</code> evaluates the
 <em class="replaceable"><code>form</code></em>, and, as a side effect, outputs detailed information about the
 memory allocations caused by this evaluation.  It also prints
 everything printed by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_time.html" target="_top"><code class="function">TIME</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="ed"></a>25.2.9. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_ed.html" target="_top"><code class="function">ED</code></a></h3></div></div></div><p>The function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_ed.html" target="_top"><code class="function">ED</code></a> calls the external editor specified by the value of
 <code class="code">(<a class="link" href="#getenv" title="32.8. Operating System Environment"><code class="function">EXT:GETENV</code></a> "EDITOR")</code> or, failing that, the value of the variable
 <strong class="first"><em class="firstterm"><a class="link" href="#ed" title="25.2.9. Function ED"><code class="varname">CUSTOM:*EDITOR*</code></a><a id="editor" class="indexterm"></a></em></strong>
  (set in <a class="link" href="#config-lisp"><code class="filename">config.lisp</code></a>).
 If the argument is a function name which was defined in the current
 session (not loaded from a file), the program text to be edited is a
 pretty-printed version (without comments) of the text which was used to
 define the function.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="apropos"></a>25.2.10. Functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_aproposcm_apropos-list.html" target="_top"><code class="function">APROPOS</code></a> &amp; <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_aproposcm_apropos-list.html" target="_top"><code class="function">APROPOS-LIST</code></a></h3></div></div></div><p>The search performed by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_aproposcm_apropos-list.html" target="_top"><code class="function">APROPOS</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_aproposcm_apropos-list.html" target="_top"><code class="function">APROPOS-LIST</code></a> is
 case-insensitive.</p><p><strong>Variable <a class="link" href="#apropos" title="25.2.10. Functions APROPOS &amp; APROPOS-LIST"><code class="varname">CUSTOM:*APROPOS-DO-MORE*</code></a>. </strong>You can make <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_aproposcm_apropos-list.html" target="_top"><code class="function">APROPOS</code></a> print more information about the symbols it
 found by setting <a class="link" href="#apropos" title="25.2.10. Functions APROPOS &amp; APROPOS-LIST"><code class="varname">CUSTOM:*APROPOS-DO-MORE*</code></a> to a list containing some of
 <code class="constant">:FUNCTION</code>, <code class="constant">:VARIABLE</code>, <code class="constant">:TYPE</code>, and <code class="constant">:CLASS</code>
 or just set it to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> to get all of the values.</p><p><strong>Variable <a class="link" href="#apropos" title="25.2.10. Functions APROPOS &amp; APROPOS-LIST"><code class="varname">CUSTOM:*APROPOS-MATCHER*</code></a>. </strong>You can make <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_aproposcm_apropos-list.html" target="_top"><code class="function">APROPOS</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_aproposcm_apropos-list.html" target="_top"><code class="function">APROPOS-LIST</code></a> be more flexible in
 their search by setting <a class="link" href="#apropos" title="25.2.10. Functions APROPOS &amp; APROPOS-LIST"><code class="varname">CUSTOM:*APROPOS-MATCHER*</code></a> to a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a> of one
 argument, a pattern (a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>), returning a new <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a> of one
 argument, a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a> name (also a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>),
 which returns non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> when the symbol name matches the pattern
 for the purposes of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_aproposcm_apropos-list.html" target="_top"><code class="function">APROPOS</code></a>.
 When <a class="link" href="#apropos" title="25.2.10. Functions APROPOS &amp; APROPOS-LIST"><code class="varname">CUSTOM:*APROPOS-MATCHER*</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_search.html" target="_top"><code class="function">SEARCH</code></a> is used.
 Some <a href="impnotes.html#modules" class="olink">module</a>s come with functions which can be used for
 <a class="link" href="#apropos" title="25.2.10. Functions APROPOS &amp; APROPOS-LIST"><code class="varname">CUSTOM:*APROPOS-MATCHER*</code></a>, e.g., <a class="link" href="#re-matcher"><code class="function">REGEXP:REGEXP-MATCHER</code></a>,
 <a class="link" href="#fnmatch-matcher" title="(POSIX:FNMATCH-MATCHER pattern)"><code class="function">POSIX:FNMATCH-MATCHER</code></a>,
 <a class="link" href="#pcre-matcher"><code class="function">PCRE:PCRE-MATCHER</code></a>.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="dribble"></a>25.2.11. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_dribble.html" target="_top"><code class="function">DRIBBLE</code></a></h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#dribble-script">25.2.11.1. Scripting and <code class="function">DRIBBLE</code></a></span></dt></dl></div><p>If <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_dribble.html" target="_top"><code class="function">DRIBBLE</code></a> is called with an argument, and dribbling is already
 enabled, a warning is printed, and the new dribbling request is
 ignored.</p><p>Dribbling is implemented via a kind (but <span class="strong"><strong>not</strong></span> a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_r.html#recognizable_subtype">recognizable subtype</a>)
 of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_two-way-stream.html" target="_top"><code class="classname">TWO-WAY-STREAM</code></a>, named <a class="link" href="#dribble" title="25.2.11. Function DRIBBLE"><code class="classname">EXT:DRIBBLE-STREAM</code></a>.
 If you have a <em class="replaceable"><code>source</code></em> <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_b.html#bidirectional">bidirectional</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> <em class="replaceable"><code>x</code></em> and you want all transactions
 (input and output) on <em class="replaceable"><code>x</code></em> to be copied to the <em class="replaceable"><code>target</code></em> <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_o.html#output">output</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> <em class="replaceable"><code>y</code></em>,
 you can do <a id="dribble-example"></a></p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defparametercm_defvar.html" target="_top"><code class="function">DEFVAR</code></a> *loggable* <em class="replaceable"><code>x</code></em>)
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/spefor_setq.html" target="_top"><code class="function">SETQ</code></a> <em class="replaceable"><code>x</code></em> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-synonym-stream.html" target="_top"><code class="function">MAKE-SYNONYM-STREAM</code></a> '*loggable*))
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defun.html" target="_top"><code class="function">DEFUN</code></a> toggle-logging (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> s)
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_multiple-value-bind.html" target="_top"><code class="function">MULTIPLE-VALUE-BIND</code></a> (source target) (dribble-toggle *loggable* s)
    (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_whencm_unless.html" target="_top"><code class="function">WHEN</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_streamp.html" target="_top"><code class="function">STREAMP</code></a> source) (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/spefor_setq.html" target="_top"><code class="function">SETQ</code></a> *loggable* source))
    target))
(toggle-logging <em class="replaceable"><code>y</code></em>)<strong>	; </strong><em class="lineannotation"><span class="lineannotation">start logging</span></em>
...
(toggle-logging)<strong>	; </strong><em class="lineannotation"><span class="lineannotation">finish logging</span></em>
...
(toggle-logging <em class="replaceable"><code>y</code></em>)<strong>	; </strong><em class="lineannotation"><span class="lineannotation">restart logging</span></em>
...
(toggle-logging)<strong>	; </strong><em class="lineannotation"><span class="lineannotation">finish logging</span></em>
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a> <em class="replaceable"><code>y</code></em>)
</pre><div class="variablelist"><dl class="variablelist"><dt><a id="drist"></a><span class="term"><code class="code">
    (<code class="function">EXT:DRIBBLE-STREAM</code> <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd>When <em class="replaceable"><code>stream</code></em> is a <a class="link" href="#dribble" title="25.2.11. Function DRIBBLE"><code class="classname">EXT:DRIBBLE-STREAM</code></a>, returns two values:
    the <em class="replaceable"><code>source</code></em> and the <em class="replaceable"><code>target</code></em> streams.  Otherwise returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
 </dd><dt><a id="drist-p"></a><span class="term"><code class="code">
    (<code class="function">EXT:DRIBBLE-STREAM-P</code> <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd>When <em class="replaceable"><code>stream</code></em> is a <a class="link" href="#dribble" title="25.2.11. Function DRIBBLE"><code class="classname">EXT:DRIBBLE-STREAM</code></a>, returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>, otherwise
    returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</dd><dt><a id="drist-so"></a><span class="term"><code class="code">
    (<code class="function">EXT:DRIBBLE-STREAM-SOURCE</code> <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd>When <em class="replaceable"><code>stream</code></em> is a <a class="link" href="#dribble" title="25.2.11. Function DRIBBLE"><code class="classname">EXT:DRIBBLE-STREAM</code></a>, returns its
    <em class="replaceable"><code>source</code></em> stream, otherwise signals a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_type-error.html" target="_top"><code class="classname">TYPE-ERROR</code></a>.
 </dd><dt><a id="drist-ta"></a><span class="term"><code class="code">
    (<code class="function">EXT:DRIBBLE-STREAM-TARGET</code> <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd>When <em class="replaceable"><code>stream</code></em> is a <a class="link" href="#dribble" title="25.2.11. Function DRIBBLE"><code class="classname">EXT:DRIBBLE-STREAM</code></a>, returns its
    <em class="replaceable"><code>target</code></em> stream, otherwise signals a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_type-error.html" target="_top"><code class="classname">TYPE-ERROR</code></a>.
 </dd><dt><a id="mk-drist"></a><span class="term"><code class="code">
     (<code class="function">EXT:MAKE-DRIBBLE-STREAM</code>
     <em class="replaceable"><code>source</code></em> <em class="replaceable"><code>target</code></em>)</code></span></dt><dd>Create a new <a class="link" href="#dribble" title="25.2.11. Function DRIBBLE"><code class="classname">EXT:DRIBBLE-STREAM</code></a>.
 </dd><dt><a id="dri-toggle"></a><span class="term"><code class="code">
    (<code class="function">EXT:DRIBBLE-TOGGLE</code> <em class="replaceable"><code>stream</code></em>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>pathname</code></em>)</code></span></dt><dd>When <em class="replaceable"><code>stream</code></em> is a <a class="link" href="#dribble" title="25.2.11. Function DRIBBLE"><code class="classname">EXT:DRIBBLE-STREAM</code></a> and <em class="replaceable"><code>pathname</code></em> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>,
    writes a dribble termination note to the <em class="replaceable"><code>stream</code></em>'s <em class="replaceable"><code>target</code></em>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> and returns <em class="replaceable"><code>stream</code></em>'s <em class="replaceable"><code>source</code></em> and <em class="replaceable"><code>target</code></em>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s;
    when <em class="replaceable"><code>stream</code></em> is not a <a class="link" href="#dribble" title="25.2.11. Function DRIBBLE"><code class="classname">EXT:DRIBBLE-STREAM</code></a> and <em class="replaceable"><code>pathname</code></em> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>,
    creates a new <a class="link" href="#dribble" title="25.2.11. Function DRIBBLE"><code class="classname">EXT:DRIBBLE-STREAM</code></a>, dribbling from <em class="replaceable"><code>stream</code></em> to <em class="replaceable"><code>pathname</code></em>,
    writes a dribble initialization note to <em class="replaceable"><code>pathname</code></em>,
    and return the <a class="link" href="#dribble" title="25.2.11. Function DRIBBLE"><code class="classname">EXT:DRIBBLE-STREAM</code></a> (the second value is the <em class="replaceable"><code>target</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>);
    otherwise <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_warn.html" target="_top"><code class="function">WARN</code></a> that no appropriate action may be taken.
    <em class="replaceable"><code>pathname</code></em> may be an open <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_o.html#output">output</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> or a <a class="link" href="#path-des" title="Pathname Designators">pathname designator</a>.
    See <a class="link" href="#dribble-example">above</a> for the sample usage.
    See also <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/dribble.lisp"><code class="filename">src/dribble.lisp</code></a> in
    the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> source tree.
</dd></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="dribble-script"></a>25.2.11.1. Scripting and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_dribble.html" target="_top"><code class="function">DRIBBLE</code></a></h4></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_dribble.html" target="_top"><code class="function">DRIBBLE</code></a> works by operating on <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stterminal-iost.html" target="_top"><code class="varname">*TERMINAL-IO*</code></a>,
 thus is does <span class="strong"><strong>not</strong></span> work when <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> acts as a script interpreter
 (see <a class="xref" href="#quickstart-unix" title="32.6.2. Scripting with CLISP">Section 32.6.2, “Scripting with <span class="command"><strong>CLISP</strong></span>”</a>).</p><p>Traditionally, <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> implementations set <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-INPUT*</code></a>,
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-OUTPUT*</code></a>, and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*ERROR-OUTPUT*</code></a> to a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_synonym-stream.html" target="_top"><code class="classname">SYNONYM-STREAM</code></a>
 pointing to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stterminal-iost.html" target="_top"><code class="varname">*TERMINAL-IO*</code></a>, and <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> is no exception.
 Thus changing <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stterminal-iost.html" target="_top"><code class="varname">*TERMINAL-IO*</code></a> to a dribble stream affects all
 standard i/o.</p><p>On the other hand, when <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> acts as a script interpreter, it
 adheres to the <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/stdio.h.html">&lt;<code class="filename">stdio.h</code>&gt;</a> <a class="link" href="#script-exec" title="Script execution">conventions</a>,
 thus <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-INPUT*</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-OUTPUT*</code></a>, and
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*ERROR-OUTPUT*</code></a> are normal <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_file-stream.html" target="_top"><code class="classname">FILE-STREAM</code></a>s,
 and thus are <span class="strong"><strong>not</strong></span> affected by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_dribble.html" target="_top"><code class="function">DRIBBLE</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stterminal-iost.html" target="_top"><code class="varname">*TERMINAL-IO*</code></a> - and
 thus <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">PRINT</code></a> ... <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>)</code> - <span class="strong"><strong>is</strong></span> still affected).
 The [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] explicitly permits this behavior by stating
 </p><div class="blockquote"><blockquote class="blockquote"><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_dribble.html" target="_top"><code class="function">DRIBBLE</code></a> is intended primarily for interactive
   debugging; its effect cannot be relied upon when used in a program.
</p></blockquote></div></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="environment-enq"></a>25.3. Environment Inquiry
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-3.html">[sec_25-1-3]</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#room">25.3.1. Function <code class="function">ROOM</code></a></span></dt><dt><span class="section"><a href="#gc-sect">25.3.2. Function <code class="function">EXT:GC</code>
   </a></span></dt><dt><span class="section"><a href="#machine">25.3.3. Machine</a></span></dt><dt><span class="section"><a href="#version">25.3.4. Function <code class="function">LISP-IMPLEMENTATION-VERSION</code></a></span></dt><dt><span class="section"><a href="#argv">25.3.5. Function <code class="function">EXT:ARGV</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="room"></a>25.3.1. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_room.html" target="_top"><code class="function">ROOM</code></a></h3></div></div></div><p>The function <strong class="first"><em class="firstterm"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_room.html" target="_top"><code class="function">ROOM</code></a>
  <a id="room-func" class="indexterm"></a></em></strong>
  returns five values:</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">space occupied by Lisp objects (in
    bytes)</li><li class="listitem">space available for allocating Lisp objects until
    the next <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion is triggered (in bytes)</li><li class="listitem">space permanently allocated (in
    bytes)</li><li class="listitem">the number of times <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion was done in this
    <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> session</li><li class="listitem">the cumulative space freed by all the <a href="impnotes.html#gc" class="olink">garbage-collect</a>ions in
    this <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> session (in bytes)</li><li class="listitem">the total time (in <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_intern_s-per-second.html" target="_top"><code class="constant">INTERNAL-TIME-UNITS-PER-SECOND</code></a>)
    spent collecting garbage</li></ol></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="gc-sect"></a>25.3.2. Function <strong class="first"><em class="firstterm"><code class="function">EXT:GC</code>
   <a id="gc-func" class="indexterm"></a></em></strong></h3></div></div></div><p>This function starts a global <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion and returns the same values
 as <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_room.html" target="_top"><code class="function">ROOM</code></a>.</p><p>When the optional parameter is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> also invalidates
 just-in-time compiled objects.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="machine"></a>25.3.3. Machine</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> platform only.</span></span></span></dt><dd>The functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_short-sit_ng-site-name.html" target="_top"><code class="function">SHORT-SITE-NAME</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_short-sit_ng-site-name.html" target="_top"><code class="function">LONG-SITE-NAME</code></a>
   should be defined in a site-specific <a class="link" href="#config-lisp"><code class="filename">config.lisp</code></a> file.
   The default implementations try to read the value of the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html">environment variable</a>
   <code class="envar">ORGANIZATION</code>, and, failing that,
   call <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/uname.html"><code class="function">uname</code></a>.
</dd><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platform only.</span></span></span></dt><dd>The functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_short-sit_ng-site-name.html" target="_top"><code class="function">SHORT-SITE-NAME</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_short-sit_ng-site-name.html" target="_top"><code class="function">LONG-SITE-NAME</code></a>
   should be defined in a site-specific <a class="link" href="#config-lisp"><code class="filename">config.lisp</code></a> file.
   The default implementations try to read the registry.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="version"></a>25.3.4. Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_lisp-impl_tion-version.html" target="_top"><code class="function">LISP-IMPLEMENTATION-VERSION</code></a></h3></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_lisp-impl_tion-version.html" target="_top"><code class="function">LISP-IMPLEMENTATION-VERSION</code></a> returns
 the numeric version (like <code class="literal">3.14</code>), and
 the release date (like <code class="literal">"1999-07-21"</code>).
 When running on the same machine on which <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> was built, it appends
  the binary build and <a href="impnotes.html#image" class="olink">memory image</a> dump date in <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-4-2.html">universal time</a>
  (like <code class="literal">3141592654</code>).
 When running on a different machine, it appends the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_machine-instance.html" target="_top"><code class="function">MACHINE-INSTANCE</code></a>
  of the machine on which it was built.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="argv"></a>25.3.5. Function <a class="link" href="#argv" title="25.3.5. Function EXT:ARGV"><code class="function">EXT:ARGV</code></a></h3></div></div></div><p>This function will return a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_f.html#fresh">fresh</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-vector.html" target="_top"><code class="classname">SIMPLE-VECTOR</code></a> of
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> command line arguments passed to the runtime, including
 those already processed by <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.
 Use <a href="impnotes.html#script-exec" class="olink"><code class="varname">EXT:*ARGS*</code></a> instead of this function to get the arguments for your program.
</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="clock"></a>25.4. Time <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-4.html">[sec_25-1-4]</a></h2></div></div></div><div class="variablelist"><a id="default-tz"></a><p class="title"><strong>Default Time Zone</strong></p><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep">No platform supports this currently</span></span></span></dt><dd>The variable <strong class="first"><em class="firstterm"><a class="link" href="#default-tz" title="Default Time Zone"><code class="varname">CUSTOM:*DEFAULT-TIME-ZONE*</code></a></em></strong>
   contains the default time zone used by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_encode-universal-time.html" target="_top"><code class="function">ENCODE-UNIVERSAL-TIME</code></a> and
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_decode-universal-time.html" target="_top"><code class="function">DECODE-UNIVERSAL-TIME</code></a>.  It is initially set to -1
   (which means 1 hour east of Greenwich, i.e., Mid European Time).
</dd></dl></div><p>The <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_t.html#time_zone">time zone</a> in a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-4-1.html">decoded time</a> does not necessarily have be an
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>, but (as <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_float.html" target="_top"><code class="classname">FLOAT</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_rational.html" target="_top"><code class="classname">RATIONAL</code></a> number)
 it should be a multiple of <span class="data"><code class="literal">1/3600</code></span>.</p><div class="table"><a id="internal-time-units-table"></a><p class="title"><strong>Table 25.7. Time granularity</strong></p><div class="table-contents"><table class="table" summary="Time granularity" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">platform</th><th align="center"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a></th><th align="center"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a></th></tr></thead><tbody><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_intern_s-per-second.html" target="_top"><code class="constant">INTERNAL-TIME-UNITS-PER-SECOND</code></a></td><td align="center">1,000,000</td><td align="center">10,000,000</td></tr></tbody></table></div></div><br class="table-break" /><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_get-internal-run-time.html" target="_top"><code class="function">GET-INTERNAL-RUN-TIME</code></a> returns the amount of run time
 consumed by the current <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> process since its startup.</p></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="glossary"></a>Chapter 26. Glossary
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-26.html">[chap-26]</a></h2></div></div></div><p>No notes.</p></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="appendix"></a>Chapter 27. Appendix
  <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-a.html">[chap-a]</a></h2></div></div></div><p>No notes.</p></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="issues"></a>Chapter 28. X3J13 Issue Index
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/Issues-Categorized.html" target="_top">[CLHS-ic]</a></h2></div></div></div><p>This is the list of [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] issues and their current status in
 <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>, i.e., whether <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> supports code that makes use of the
 functionality specified by the vote.</p><div class="variablelist"><a id="issues-list"></a><p class="title"><strong>X3J13 Issues</strong></p><dl class="variablelist"><dt><a id="iss001"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss001.html" target="_top">&amp;ENVIRONMENT-BINDING-ORDER:FIRST</a></span></dt><dd>yes</dd><dt><a id="iss002"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss002.html" target="_top">ACCESS-ERROR-NAME</a></span></dt><dd>yes</dd><dt><a id="iss003"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss003.html" target="_top">ADJUST-ARRAY-DISPLACEMENT</a></span></dt><dd>yes</dd><dt><a id="iss004"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss004.html" target="_top">ADJUST-ARRAY-FILL-POINTER</a></span></dt><dd>yes</dd><dt><a id="iss005"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss005.html" target="_top">ADJUST-ARRAY-NOT-ADJUSTABLE:IMPLICIT-COPY</a></span></dt><dd>yes</dd><dt><a id="iss006"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss006.html" target="_top">ALLOCATE-INSTANCE:ADD</a></span></dt><dd>yes</dd><dt><a id="iss007"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss007.html" target="_top">ALLOW-LOCAL-INLINE:INLINE-NOTINLINE</a></span></dt><dd>yes</dd><dt><a id="iss008"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss008.html" target="_top">ALLOW-OTHER-KEYS-NIL:PERMIT</a></span></dt><dd>yes</dd><dt><a id="iss009"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss009.html" target="_top">AREF-1D</a></span></dt><dd>yes</dd><dt><a id="iss010"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss010.html" target="_top">ARGUMENT-MISMATCH-ERROR-AGAIN:CONSISTENT</a></span></dt><dd>yes</dd><dt><a id="iss011"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss011.html" target="_top">ARGUMENT-MISMATCH-ERROR-MOON:FIX</a></span></dt><dd>yes</dd><dt><a id="iss012"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss012.html" target="_top">ARGUMENT-MISMATCH-ERROR:MORE-CLARIFICATIONS</a></span></dt><dd>yes, except for argument list checking in
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locfun_call-next-method.html" target="_top"><code class="function">CALL-NEXT-METHOD</code></a> in compiled code (items 11,12)
 </dd><dt><a id="iss013"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss013.html" target="_top">ARGUMENTS-UNDERSPECIFIED:SPECIFY</a></span></dt><dd>yes</dd><dt><a id="iss014"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss014.html" target="_top">ARRAY-DIMENSION-LIMIT-IMPLICATIONS:ALL-FIXNUM</a></span></dt><dd>yes</dd><dt><a id="iss015"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss015.html" target="_top">ARRAY-TYPE-ELEMENT-TYPE-SEMANTICS:UNIFY-UPGRADING</a></span></dt><dd>yes</dd><dt><a id="iss016"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss016.html" target="_top">ASSERT-ERROR-TYPE:ERROR</a></span></dt><dd>yes</dd><dt><a id="iss017"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss017.html" target="_top">ASSOC-RASSOC-IF-KEY</a></span></dt><dd>yes</dd><dt><a id="iss018"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss018.html" target="_top">ASSOC-RASSOC-IF-KEY:YES</a></span></dt><dd>yes</dd><dt><a id="iss019"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss019.html" target="_top">BOA-AUX-INITIALIZATION:ERROR-ON-READ</a></span></dt><dd>yes</dd><dt><a id="iss020"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss020.html" target="_top">BREAK-ON-WARNINGS-OBSOLETE:REMOVE</a></span></dt><dd>yes</dd><dt><a id="iss021"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss021.html" target="_top">BROADCAST-STREAM-RETURN-VALUES:CLARIFY-MINIMALLY</a></span></dt><dd>yes</dd><dt><a id="iss022"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss022.html" target="_top">BUTLAST-NEGATIVE:SHOULD-SIGNAL</a></span></dt><dd>yes</dd><dt><a id="iss023"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss023.html" target="_top">CHANGE-CLASS-INITARGS:PERMIT</a></span></dt><dd>yes</dd><dt><a id="iss024"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss024.html" target="_top">CHAR-NAME-CASE:X3J13-MAR-91</a></span></dt><dd>yes</dd><dt><a id="iss025"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss025.html" target="_top">CHARACTER-LOOSE-ENDS:FIX</a></span></dt><dd>yes</dd><dt><a id="iss026"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss026.html" target="_top">CHARACTER-PROPOSAL:2</a></span></dt><dd>yes</dd><dt><a id="iss027"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss027.html" target="_top">CHARACTER-PROPOSAL:2-1-1</a></span></dt><dd>yes</dd><dt><a id="iss028"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss028.html" target="_top">CHARACTER-PROPOSAL:2-1-2</a></span></dt><dd>yes</dd><dt><a id="iss029"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss029.html" target="_top">CHARACTER-PROPOSAL:2-2-1</a></span></dt><dd>yes</dd><dt><a id="iss030"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss030.html" target="_top">CHARACTER-PROPOSAL:2-3-1</a></span></dt><dd>yes</dd><dt><a id="iss031"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss031.html" target="_top">CHARACTER-PROPOSAL:2-3-2</a></span></dt><dd>yes</dd><dt><a id="iss032"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss032.html" target="_top">CHARACTER-PROPOSAL:2-3-3</a></span></dt><dd>yes</dd><dt><a id="iss033"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss033.html" target="_top">CHARACTER-PROPOSAL:2-3-4</a></span></dt><dd>yes</dd><dt><a id="iss034"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss034.html" target="_top">CHARACTER-PROPOSAL:2-3-5</a></span></dt><dd>yes</dd><dt><a id="iss035"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss035.html" target="_top">CHARACTER-PROPOSAL:2-3-6</a></span></dt><dd>yes</dd><dt><a id="iss036"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss036.html" target="_top">CHARACTER-PROPOSAL:2-4-1</a></span></dt><dd>yes</dd><dt><a id="iss037"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss037.html" target="_top">CHARACTER-PROPOSAL:2-4-2</a></span></dt><dd>yes</dd><dt><a id="iss038"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss038.html" target="_top">CHARACTER-PROPOSAL:2-4-3</a></span></dt><dd>yes</dd><dt><a id="iss039"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss039.html" target="_top">CHARACTER-PROPOSAL:2-5-2</a></span></dt><dd>yes</dd><dt><a id="iss040"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss040.html" target="_top">CHARACTER-PROPOSAL:2-5-6</a></span></dt><dd>yes</dd><dt><a id="iss041"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss041.html" target="_top">CHARACTER-PROPOSAL:2-5-7</a></span></dt><dd>yes</dd><dt><a id="iss042"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss042.html" target="_top">CHARACTER-PROPOSAL:2-6-1</a></span></dt><dd>yes</dd><dt><a id="iss043"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss043.html" target="_top">CHARACTER-PROPOSAL:2-6-2</a></span></dt><dd>yes</dd><dt><a id="iss044"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss044.html" target="_top">CHARACTER-PROPOSAL:2-6-3</a></span></dt><dd>yes</dd><dt><a id="iss045"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss045.html" target="_top">CHARACTER-PROPOSAL:2-6-5</a></span></dt><dd>yes</dd><dt><a id="iss046"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss046.html" target="_top">CHARACTER-VS-CHAR:LESS-INCONSISTENT-SHORT</a></span></dt><dd>yes</dd><dt><a id="iss047"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss047.html" target="_top">CLASS-OBJECT-SPECIALIZER:AFFIRM</a></span></dt><dd>yes</dd><dt><a id="iss048"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss048.html" target="_top">CLOS-CONDITIONS-AGAIN:ALLOW-SUBSET</a></span></dt><dd>yes</dd><dt><a id="iss049"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss049.html" target="_top">CLOS-CONDITIONS:INTEGRATE</a></span></dt><dd>yes</dd><dt><a id="iss050"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss050.html" target="_top">CLOS-ERROR-CHECKING-ORDER:NO-APPLICABLE-METHOD-FIRST</a></span></dt><dd>yes</dd><dt><a id="iss051"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss051.html" target="_top">CLOS-MACRO-COMPILATION:MINIMAL</a></span></dt><dd>yes</dd><dt><a id="iss052"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss052.html" target="_top">CLOSE-CONSTRUCTED-STREAM:ARGUMENT-STREAM-ONLY</a></span></dt><dd>yes</dd><dt><a id="iss053"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss053.html" target="_top">CLOSED-STREAM-OPERATIONS:ALLOW-INQUIRY</a></span></dt><dd>yes</dd><dt><a id="iss054"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss054.html" target="_top">COERCING-SETF-NAME-TO-FUNCTION:ALL-FUNCTION-NAMES</a></span></dt><dd>yes</dd><dt><a id="iss055"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss055.html" target="_top">COLON-NUMBER</a></span></dt><dd>yes</dd><dt><a id="iss056"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss056.html" target="_top">COMMON-FEATURES:SPECIFY</a></span></dt><dd>yes</dd><dt><a id="iss057"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss057.html" target="_top">COMMON-TYPE:REMOVE</a></span></dt><dd>yes</dd><dt><a id="iss058"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss058.html" target="_top">COMPILE-ARGUMENT-PROBLEMS-AGAIN:FIX</a></span></dt><dd>yes</dd><dt><a id="iss059"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss059.html" target="_top">COMPILE-FILE-HANDLING-OF-TOP-LEVEL-FORMS:CLARIFY</a></span></dt><dd>yes</dd><dt><a id="iss060"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss060.html" target="_top">COMPILE-FILE-OUTPUT-FILE-DEFAULTS:INPUT-FILE</a></span></dt><dd>yes</dd><dt><a id="iss061"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss061.html" target="_top">COMPILE-FILE-PACKAGE</a></span></dt><dd>yes</dd><dt><a id="iss062"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss062.html" target="_top">COMPILE-FILE-PATHNAME-ARGUMENTS:MAKE-CONSISTENT</a></span></dt><dd>yes</dd><dt><a id="iss063"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss063.html" target="_top">COMPILE-FILE-SYMBOL-HANDLING:NEW-REQUIRE-CONSISTENCY</a></span></dt><dd>yes</dd><dt><a id="iss064"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss064.html" target="_top">COMPILED-FUNCTION-REQUIREMENTS:TIGHTEN</a></span></dt><dd>yes</dd><dt><a id="iss065"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss065.html" target="_top">COMPILER-DIAGNOSTICS:USE-HANDLER</a></span></dt><dd>yes</dd><dt><a id="iss066"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss066.html" target="_top">COMPILER-LET-CONFUSION:ELIMINATE</a></span></dt><dd>yes</dd><dt><a id="iss067"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss067.html" target="_top">COMPILER-VERBOSITY:LIKE-LOAD</a></span></dt><dd>yes</dd><dt><a id="iss068"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss068.html" target="_top">COMPILER-WARNING-STREAM</a></span></dt><dd>yes</dd><dt><a id="iss069"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss069.html" target="_top">COMPLEX-ATAN-BRANCH-CUT:TWEAK</a></span></dt><dd>yes</dd><dt><a id="iss070"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss070.html" target="_top">COMPLEX-ATANH-BOGUS-FORMULA:TWEAK-MORE</a></span></dt><dd>yes</dd><dt><a id="iss071"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss071.html" target="_top">COMPLEX-RATIONAL-RESULT:EXTEND</a></span></dt><dd>yes</dd><dt><a id="iss072"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss072.html" target="_top">COMPUTE-APPLICABLE-METHODS:GENERIC</a></span></dt><dd>yes</dd><dt><a id="iss073"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss073.html" target="_top">CONCATENATE-SEQUENCE:SIGNAL-ERROR</a></span></dt><dd>yes</dd><dt><a id="iss074"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss074.html" target="_top">CONDITION-ACCESSORS-SETFABLE:NO</a></span></dt><dd>yes</dd><dt><a id="iss075"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss075.html" target="_top">CONDITION-RESTARTS:BUGGY</a></span></dt><dd>yes</dd><dt><a id="iss076"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss076.html" target="_top">CONDITION-RESTARTS:PERMIT-ASSOCIATION</a></span></dt><dd>yes</dd><dt><a id="iss077"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss077.html" target="_top">CONDITION-SLOTS:HIDDEN</a></span></dt><dd>yes</dd><dt><a id="iss078"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss078.html" target="_top">CONS-TYPE-SPECIFIER:ADD</a></span></dt><dd>yes</dd><dt><a id="iss079"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss079.html" target="_top">CONSTANT-CIRCULAR-COMPILATION:YES</a></span></dt><dd>yes</dd><dt><a id="iss080"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss080.html" target="_top">CONSTANT-COLLAPSING:GENERALIZE</a></span></dt><dd>yes</dd><dt><a id="iss081"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss081.html" target="_top">CONSTANT-COMPILABLE-TYPES:SPECIFY</a></span></dt><dd>yes</dd><dt><a id="iss082"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss082.html" target="_top">CONSTANT-FUNCTION-COMPILATION:NO</a></span></dt><dd><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> can dump compiled functions defined in the
    global <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a>. Interpreted functions can <span class="strong"><strong>not</strong></span> be dumped;
    this should not be a problem, because an
    <span class="emphasis"><em>interpreted</em></span> function in a
    <span class="emphasis"><em>compiled</em></span> file usually indicate a programmer
    error (often an extra <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_quote.html" target="_top"><code class="function">QUOTE</code></a>).</dd><dt><a id="iss083"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss083.html" target="_top">CONSTANT-MODIFICATION:DISALLOW</a></span></dt><dd>yes</dd><dt><a id="iss084"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss084.html" target="_top">CONSTANTP-DEFINITION:INTENTIONAL</a></span></dt><dd>yes</dd><dt><a id="iss085"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss085.html" target="_top">CONSTANTP-ENVIRONMENT:ADD-ARG</a></span></dt><dd>yes</dd><dt><a id="iss086"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss086.html" target="_top">CONTAGION-ON-NUMERICAL-COMPARISONS:TRANSITIVE</a></span></dt><dd>yes</dd><dt><a id="iss087"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss087.html" target="_top">COPY-SYMBOL-COPY-PLIST:COPY-LIST</a></span></dt><dd>yes</dd><dt><a id="iss088"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss088.html" target="_top">COPY-SYMBOL-PRINT-NAME:EQUAL</a></span></dt><dd>yes</dd><dt><a id="iss089"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss089.html" target="_top">DATA-IO:ADD-SUPPORT</a></span></dt><dd>yes</dd><dt><a id="iss090"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss090.html" target="_top">DATA-TYPES-HIERARCHY-UNDERSPECIFIED</a></span></dt><dd>yes</dd><dt><a id="iss091"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss091.html" target="_top">DEBUGGER-HOOK-VS-BREAK:CLARIFY</a></span></dt><dd>yes</dd><dt><a id="iss092"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss092.html" target="_top">DECLARATION-SCOPE:NO-HOISTING</a></span></dt><dd>yes</dd><dt><a id="iss093"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss093.html" target="_top">DECLARE-ARRAY-TYPE-ELEMENT-REFERENCES:RESTRICTIVE</a></span></dt><dd>yes</dd><dt><a id="iss094"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss094.html" target="_top">DECLARE-FUNCTION-AMBIGUITY:DELETE-FTYPE-ABBREVIATION</a></span></dt><dd>yes</dd><dt><a id="iss095"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss095.html" target="_top">DECLARE-MACROS:FLUSH</a></span></dt><dd>yes</dd><dt><a id="iss096"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss096.html" target="_top">DECLARE-TYPE-FREE:LEXICAL</a></span></dt><dd>yes</dd><dt><a id="iss097"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss097.html" target="_top">DECLS-AND-DOC</a></span></dt><dd>there is no writeup, but all affected
    operators are fully implemented as specified
 </dd><dt><a id="iss098"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss098.html" target="_top">DECODE-UNIVERSAL-TIME-DAYLIGHT:LIKE-ENCODE</a></span></dt><dd>yes</dd><dt><a id="iss099"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss099.html" target="_top">DEFCONSTANT-SPECIAL:NO</a></span></dt><dd>yes</dd><dt><a id="iss100"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss100.html" target="_top">DEFGENERIC-DECLARE:ALLOW-MULTIPLE</a></span></dt><dd>yes</dd><dt><a id="iss101"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss101.html" target="_top">DEFINE-COMPILER-MACRO:X3J13-NOV89</a></span></dt><dd>yes</dd><dt><a id="iss102"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss102.html" target="_top">DEFINE-CONDITION-SYNTAX:INCOMPATIBLY-MORE-LIKE-DEFCLASS+EMPHASIZE-READ-ONLY</a></span></dt><dd>yes</dd><dt><a id="iss103"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss103.html" target="_top">DEFINE-METHOD-COMBINATION-BEHAVIOR:CLARIFY</a></span></dt><dd>no</dd><dt><a id="iss104"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss104.html" target="_top">DEFINING-MACROS-NON-TOP-LEVEL:ALLOW</a></span></dt><dd>yes</dd><dt><a id="iss105"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss105.html" target="_top">DEFMACRO-BLOCK-SCOPE:EXCLUDES-BINDINGS</a></span></dt><dd>yes</dd><dt><a id="iss106"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss106.html" target="_top">DEFMACRO-LAMBDA-LIST:TIGHTEN-DESCRIPTION</a></span></dt><dd>yes</dd><dt><a id="iss107"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss107.html" target="_top">DEFMETHOD-DECLARATION-SCOPE:CORRESPONDS-TO-BINDINGS</a></span></dt><dd>yes</dd><dt><a id="iss108"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss108.html" target="_top">DEFPACKAGE:ADDITION</a></span></dt><dd>yes</dd><dt><a id="iss109"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss109.html" target="_top">DEFSTRUCT-CONSTRUCTOR-KEY-MIXTURE:ALLOW-KEY</a></span></dt><dd>yes</dd><dt><a id="iss110"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss110.html" target="_top">DEFSTRUCT-CONSTRUCTOR-OPTIONS:EXPLICIT</a></span></dt><dd>yes</dd><dt><a id="iss111"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss111.html" target="_top">DEFSTRUCT-CONSTRUCTOR-SLOT-VARIABLES:NOT-BOUND</a></span></dt><dd>yes</dd><dt><a id="iss112"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss112.html" target="_top">DEFSTRUCT-COPIER-ARGUMENT-TYPE:RESTRICT</a></span></dt><dd>yes</dd><dt><a id="iss113"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss113.html" target="_top">DEFSTRUCT-COPIER:ARGUMENT-TYPE</a></span></dt><dd>yes</dd><dt><a id="iss114"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss114.html" target="_top">DEFSTRUCT-DEFAULT-VALUE-EVALUATION:IFF-NEEDED</a></span></dt><dd>yes</dd><dt><a id="iss115"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss115.html" target="_top">DEFSTRUCT-INCLUDE-DEFTYPE:EXPLICITLY-UNDEFINED</a></span></dt><dd>yes</dd><dt><a id="iss116"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss116.html" target="_top">DEFSTRUCT-PRINT-FUNCTION-AGAIN:X3J13-MAR-93</a></span></dt><dd>yes</dd><dt><a id="iss117"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss117.html" target="_top">DEFSTRUCT-PRINT-FUNCTION-INHERITANCE:YES</a></span></dt><dd>yes</dd><dt><a id="iss118"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss118.html" target="_top">DEFSTRUCT-REDEFINITION:ERROR</a></span></dt><dd>yes</dd><dt><a id="iss119"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss119.html" target="_top">DEFSTRUCT-SLOTS-CONSTRAINTS-NAME:DUPLICATES-ERROR</a></span></dt><dd>yes</dd><dt><a id="iss120"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss120.html" target="_top">DEFSTRUCT-SLOTS-CONSTRAINTS-NUMBER</a></span></dt><dd>yes</dd><dt><a id="iss121"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss121.html" target="_top">DEFTYPE-DESTRUCTURING:YES</a></span></dt><dd>yes</dd><dt><a id="iss122"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss122.html" target="_top">DEFTYPE-KEY:ALLOW</a></span></dt><dd>yes</dd><dt><a id="iss123"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss123.html" target="_top">DEFVAR-DOCUMENTATION:UNEVALUATED</a></span></dt><dd>yes</dd><dt><a id="iss124"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss124.html" target="_top">DEFVAR-INIT-TIME:NOT-DELAYED</a></span></dt><dd>yes</dd><dt><a id="iss125"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss125.html" target="_top">DEFVAR-INITIALIZATION:CONSERVATIVE</a></span></dt><dd>yes</dd><dt><a id="iss126"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss126.html" target="_top">DEPRECATION-POSITION:LIMITED</a></span></dt><dd>yes</dd><dt><a id="iss127"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss127.html" target="_top">DESCRIBE-INTERACTIVE:NO</a></span></dt><dd>yes</dd><dt><a id="iss128"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss128.html" target="_top">DESCRIBE-UNDERSPECIFIED:DESCRIBE-OBJECT</a></span></dt><dd>yes</dd><dt><a id="iss129"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss129.html" target="_top">DESTRUCTIVE-OPERATIONS:SPECIFY</a></span></dt><dd>yes</dd><dt><a id="iss130"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss130.html" target="_top">DESTRUCTURING-BIND:NEW-MACRO</a></span></dt><dd>yes</dd><dt><a id="iss131"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss131.html" target="_top">DISASSEMBLE-SIDE-EFFECT:DO-NOT-INSTALL</a></span></dt><dd>yes</dd><dt><a id="iss132"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss132.html" target="_top">DISPLACED-ARRAY-PREDICATE:ADD</a></span></dt><dd>yes</dd><dt><a id="iss133"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss133.html" target="_top">DO-SYMBOLS-BLOCK-SCOPE:ENTIRE-FORM</a></span></dt><dd>yes</dd><dt><a id="iss134"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss134.html" target="_top">DO-SYMBOLS-DUPLICATES</a></span></dt><dd>yes</dd><dt><a id="iss135"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss135.html" target="_top">DOCUMENTATION-FUNCTION-BUGS:FIX</a></span></dt><dd>yes</dd><dt><a id="iss136"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss136.html" target="_top">DOCUMENTATION-FUNCTION-TANGLED:REQUIRE-ARGUMENT</a></span></dt><dd>yes</dd><dt><a id="iss137"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss137.html" target="_top">DOTIMES-IGNORE:X3J13-MAR91</a></span></dt><dd>yes</dd><dt><a id="iss138"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss138.html" target="_top">DOTTED-LIST-ARGUMENTS:CLARIFY</a></span></dt><dd>yes</dd><dt><a id="iss139"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss139.html" target="_top">DOTTED-MACRO-FORMS:ALLOW</a></span></dt><dd>yes</dd><dt><a id="iss140"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss140.html" target="_top">DRIBBLE-TECHNIQUE</a></span></dt><dd>yes</dd><dt><a id="iss141"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss141.html" target="_top">DYNAMIC-EXTENT-FUNCTION:EXTEND</a></span></dt><dd>yes</dd><dt><a id="iss142"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss142.html" target="_top">DYNAMIC-EXTENT:NEW-DECLARATION</a></span></dt><dd>yes</dd><dt><a id="iss143"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss143.html" target="_top">EQUAL-STRUCTURE:MAYBE-STATUS-QUO</a></span></dt><dd>yes</dd><dt><a id="iss144"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss144.html" target="_top">ERROR-TERMINOLOGY-WARNING:MIGHT</a></span></dt><dd>yes</dd><dt><a id="iss145"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss145.html" target="_top">EVAL-OTHER:SELF-EVALUATE</a></span></dt><dd>yes</dd><dt><a id="iss146"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss146.html" target="_top">EVAL-TOP-LEVEL:LOAD-LIKE-COMPILE-FILE</a></span></dt><dd>yes</dd><dt><a id="iss147"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss147.html" target="_top">EVAL-WHEN-NON-TOP-LEVEL:GENERALIZE-EVAL-NEW-KEYWORDS</a></span></dt><dd>yes</dd><dt><a id="iss148"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss148.html" target="_top">EVAL-WHEN-OBSOLETE-KEYWORDS:X3J13-MAR-1993</a></span></dt><dd>no</dd><dt><a id="iss149"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss149.html" target="_top">EVALHOOK-STEP-CONFUSION:FIX</a></span></dt><dd>yes</dd><dt><a id="iss150"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss150.html" target="_top">EVALHOOK-STEP-CONFUSION:X3J13-NOV-89</a></span></dt><dd>yes</dd><dt><a id="iss151"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss151.html" target="_top">EXIT-EXTENT-AND-CONDITION-SYSTEM:LIKE-DYNAMIC-BINDINGS</a></span></dt><dd>yes</dd><dt><a id="iss152"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss152.html" target="_top">EXIT-EXTENT:MINIMAL</a></span></dt><dd>yes, actually implement MEDIUM
 </dd><dt><a id="iss153"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss153.html" target="_top">EXPT-RATIO:P.211</a></span></dt><dd>yes</dd><dt><a id="iss154"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss154.html" target="_top">EXTENSIONS-POSITION:DOCUMENTATION</a></span></dt><dd>yes</dd><dt><a id="iss155"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss155.html" target="_top">EXTERNAL-FORMAT-FOR-EVERY-FILE-CONNECTION:MINIMUM</a></span></dt><dd>yes</dd><dt><a id="iss156"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss156.html" target="_top">EXTRA-RETURN-VALUES:NO</a></span></dt><dd>yes</dd><dt><a id="iss157"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss157.html" target="_top">FILE-OPEN-ERROR:SIGNAL-FILE-ERROR</a></span></dt><dd>yes</dd><dt><a id="iss158"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss158.html" target="_top">FIXNUM-NON-PORTABLE:TIGHTEN-DEFINITION</a></span></dt><dd>yes</dd><dt><a id="iss159"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss159.html" target="_top">FLET-DECLARATIONS</a></span></dt><dd>yes</dd><dt><a id="iss160"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss160.html" target="_top">FLET-DECLARATIONS:ALLOW</a></span></dt><dd>yes</dd><dt><a id="iss161"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss161.html" target="_top">FLET-IMPLICIT-BLOCK:YES</a></span></dt><dd>yes</dd><dt><a id="iss162"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss162.html" target="_top">FLOAT-UNDERFLOW:ADD-VARIABLES</a></span></dt><dd>yes</dd><dt><a id="iss163"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss163.html" target="_top">FLOATING-POINT-CONDITION-NAMES:X3J13-NOV-89</a></span></dt><dd>yes</dd><dt><a id="iss164"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss164.html" target="_top">FORMAT-ATSIGN-COLON</a></span></dt><dd>yes</dd><dt><a id="iss165"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss165.html" target="_top">FORMAT-COLON-UPARROW-SCOPE</a></span></dt><dd>yes</dd><dt><a id="iss166"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss166.html" target="_top">FORMAT-COMMA-INTERVAL</a></span></dt><dd>yes</dd><dt><a id="iss167"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss167.html" target="_top">FORMAT-E-EXPONENT-SIGN:FORCE-SIGN</a></span></dt><dd>yes</dd><dt><a id="iss168"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss168.html" target="_top">FORMAT-OP-C</a></span></dt><dd>yes</dd><dt><a id="iss169"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss169.html" target="_top">FORMAT-PRETTY-PRINT:YES</a></span></dt><dd>yes, except that <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-3-1.html"><code class="literal">~F</code></a>, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-3-2.html"><code class="literal">~E</code></a>,
    <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-3-3.html"><code class="literal">~G</code></a>, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-3-4.html"><code class="literal">~$</code></a> also bind <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-b_rint-radixst.html" target="_top"><code class="varname">*PRINT-BASE*</code></a> to 10 and
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-b_rint-radixst.html" target="_top"><code class="varname">*PRINT-RADIX*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></dd><dt><a id="iss170"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss170.html" target="_top">FORMAT-STRING-ARGUMENTS:SPECIFY</a></span></dt><dd>yes</dd><dt><a id="iss171"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss171.html" target="_top">FUNCTION-CALL-EVALUATION-ORDER:MORE-UNSPECIFIED</a></span></dt><dd>yes</dd><dt><a id="iss172"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss172.html" target="_top">FUNCTION-COMPOSITION:JAN89-X3J13</a></span></dt><dd>yes</dd><dt><a id="iss173"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss173.html" target="_top">FUNCTION-DEFINITION:JAN89-X3J13</a></span></dt><dd>yes</dd><dt><a id="iss174"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss174.html" target="_top">FUNCTION-NAME:LARGE</a></span></dt><dd>yes</dd><dt><a id="iss175"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss175.html" target="_top">FUNCTION-TYPE</a></span></dt><dd>yes</dd><dt><a id="iss176"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss176.html" target="_top">FUNCTION-TYPE-ARGUMENT-TYPE-SEMANTICS:RESTRICTIVE</a></span></dt><dd>yes</dd><dt><a id="iss177"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss177.html" target="_top">FUNCTION-TYPE-KEY-NAME:SPECIFY-KEYWORD</a></span></dt><dd>yes</dd><dt><a id="iss178"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss178.html" target="_top">FUNCTION-TYPE-REST-LIST-ELEMENT:USE-ACTUAL-ARGUMENT-TYPE</a></span></dt><dd>yes</dd><dt><a id="iss179"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss179.html" target="_top">FUNCTION-TYPE:X3J13-MARCH-88</a></span></dt><dd>yes</dd><dt><a id="iss180"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss180.html" target="_top">GENERALIZE-PRETTY-PRINTER:UNIFY</a></span></dt><dd>no</dd><dt><a id="iss181"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss181.html" target="_top">GENERIC-FLET-POORLY-DESIGNED:DELETE</a></span></dt><dd>yes</dd><dt><a id="iss182"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss182.html" target="_top">GENSYM-NAME-STICKINESS:LIKE-TEFLON</a></span></dt><dd>yes</dd><dt><a id="iss183"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss183.html" target="_top">GENTEMP-BAD-IDEA:DEPRECATE</a></span></dt><dd>yes</dd><dt><a id="iss184"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss184.html" target="_top">GET-MACRO-CHARACTER-READTABLE:NIL-STANDARD</a></span></dt><dd>yes</dd><dt><a id="iss185"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss185.html" target="_top">GET-SETF-METHOD-ENVIRONMENT:ADD-ARG</a></span></dt><dd>yes</dd><dt><a id="iss186"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss186.html" target="_top">HASH-TABLE-ACCESS:X3J13-MAR-89</a></span></dt><dd>yes</dd><dt><a id="iss187"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss187.html" target="_top">HASH-TABLE-KEY-MODIFICATION:SPECIFY</a></span></dt><dd>yes</dd><dt><a id="iss188"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss188.html" target="_top">HASH-TABLE-PACKAGE-GENERATORS:ADD-WITH-WRAPPER</a></span></dt><dd>yes</dd><dt><a id="iss189"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss189.html" target="_top">HASH-TABLE-REHASH-SIZE-INTEGER</a></span></dt><dd>yes</dd><dt><a id="iss190"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss190.html" target="_top">HASH-TABLE-SIZE:INTENDED-ENTRIES</a></span></dt><dd>yes</dd><dt><a id="iss191"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss191.html" target="_top">HASH-TABLE-TESTS:ADD-EQUALP</a></span></dt><dd>yes</dd><dt><a id="iss192"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss192.html" target="_top">IEEE-ATAN-BRANCH-CUT:SPLIT</a></span></dt><dd>yes</dd><dt><a id="iss193"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss193.html" target="_top">IGNORE-USE-TERMINOLOGY:VALUE-ONLY</a></span></dt><dd>yes</dd><dt><a id="iss194"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss194.html" target="_top">IMPORT-SETF-SYMBOL-PACKAGE</a></span></dt><dd>yes</dd><dt><a id="iss195"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss195.html" target="_top">IN-PACKAGE-FUNCTIONALITY:MAR89-X3J13</a></span></dt><dd>yes</dd><dt><a id="iss196"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss196.html" target="_top">IN-SYNTAX:MINIMAL</a></span></dt><dd>yes</dd><dt><a id="iss197"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss197.html" target="_top">INITIALIZATION-FUNCTION-KEYWORD-CHECKING</a></span></dt><dd>yes</dd><dt><a id="iss198"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss198.html" target="_top">ISO-COMPATIBILITY:ADD-SUBSTRATE</a></span></dt><dd>yes</dd><dt><a id="iss199"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss199.html" target="_top">JUN90-TRIVIAL-ISSUES:11</a></span></dt><dd>yes</dd><dt><a id="iss200"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss200.html" target="_top">JUN90-TRIVIAL-ISSUES:14</a></span></dt><dd>yes</dd><dt><a id="iss201"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss201.html" target="_top">JUN90-TRIVIAL-ISSUES:24</a></span></dt><dd>yes</dd><dt><a id="iss202"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss202.html" target="_top">JUN90-TRIVIAL-ISSUES:25</a></span></dt><dd>yes</dd><dt><a id="iss203"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss203.html" target="_top">JUN90-TRIVIAL-ISSUES:27</a></span></dt><dd>yes for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_the.html" target="_top"><code class="function">THE</code></a>, no for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_apply.html" target="_top"><code class="function">APPLY</code></a> (spec not clear)
 </dd><dt><a id="iss204"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss204.html" target="_top">JUN90-TRIVIAL-ISSUES:3</a></span></dt><dd>yes</dd><dt><a id="iss205"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss205.html" target="_top">JUN90-TRIVIAL-ISSUES:4</a></span></dt><dd>yes</dd><dt><a id="iss206"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss206.html" target="_top">JUN90-TRIVIAL-ISSUES:5</a></span></dt><dd>yes</dd><dt><a id="iss207"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss207.html" target="_top">JUN90-TRIVIAL-ISSUES:9</a></span></dt><dd>yes</dd><dt><a id="iss208"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss208.html" target="_top">KEYWORD-ARGUMENT-NAME-PACKAGE:ANY</a></span></dt><dd>yes</dd><dt><a id="iss209"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss209.html" target="_top">LAST-N</a></span></dt><dd>yes</dd><dt><a id="iss210"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss210.html" target="_top">LCM-NO-ARGUMENTS:1</a></span></dt><dd>yes</dd><dt><a id="iss211"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss211.html" target="_top">LEXICAL-CONSTRUCT-GLOBAL-DEFINITION:UNDEFINED</a></span></dt><dd>yes</dd><dt><a id="iss212"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss212.html" target="_top">LISP-PACKAGE-NAME:COMMON-LISP</a></span></dt><dd>yes</dd><dt><a id="iss213"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss213.html" target="_top">LISP-SYMBOL-REDEFINITION-AGAIN:MORE-FIXES</a></span></dt><dd>yes</dd><dt><a id="iss214"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss214.html" target="_top">LISP-SYMBOL-REDEFINITION:MAR89-X3J13</a></span></dt><dd>yes</dd><dt><a id="iss215"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss215.html" target="_top">LOAD-OBJECTS:MAKE-LOAD-FORM</a></span></dt><dd>yes</dd><dt><a id="iss216"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss216.html" target="_top">LOAD-TIME-EVAL:R**2-NEW-SPECIAL-FORM</a></span></dt><dd>obsolete</dd><dt><a id="iss217"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss217.html" target="_top">LOAD-TIME-EVAL:R**3-NEW-SPECIAL-FORM</a></span></dt><dd>yes</dd><dt><a id="iss218"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss218.html" target="_top">LOAD-TRUENAME:NEW-PATHNAME-VARIABLES</a></span></dt><dd>yes</dd><dt><a id="iss219"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss219.html" target="_top">LOCALLY-TOP-LEVEL:SPECIAL-FORM</a></span></dt><dd>yes</dd><dt><a id="iss220"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss220.html" target="_top">LOOP-AND-DISCREPANCY:NO-REITERATION</a></span></dt><dd>yes</dd><dt><a id="iss221"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss221.html" target="_top">LOOP-FOR-AS-ON-TYPO:FIX-TYPO</a></span></dt><dd>yes</dd><dt><a id="iss222"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss222.html" target="_top">LOOP-INITFORM-ENVIRONMENT:PARTIAL-INTERLEAVING-VAGUE</a></span></dt><dd>no</dd><dt><a id="iss223"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss223.html" target="_top">LOOP-MISCELLANEOUS-REPAIRS:FIX</a></span></dt><dd>yes</dd><dt><a id="iss224"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss224.html" target="_top">LOOP-NAMED-BLOCK-NIL:OVERRIDE</a></span></dt><dd>yes</dd><dt><a id="iss225"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss225.html" target="_top">LOOP-PRESENT-SYMBOLS-TYPO:FLUSH-WRONG-WORDS</a></span></dt><dd>yes</dd><dt><a id="iss226"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss226.html" target="_top">LOOP-SYNTAX-OVERHAUL:REPAIR</a></span></dt><dd>yes</dd><dt><a id="iss227"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss227.html" target="_top">MACRO-AS-FUNCTION:DISALLOW</a></span></dt><dd>yes</dd><dt><a id="iss228"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss228.html" target="_top">MACRO-DECLARATIONS:MAKE-EXPLICIT</a></span></dt><dd>yes</dd><dt><a id="iss229"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss229.html" target="_top">MACRO-ENVIRONMENT-EXTENT:DYNAMIC</a></span></dt><dd>yes</dd><dt><a id="iss230"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss230.html" target="_top">MACRO-FUNCTION-ENVIRONMENT</a></span></dt><dd>obsolete</dd><dt><a id="iss231"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss231.html" target="_top">MACRO-FUNCTION-ENVIRONMENT:YES</a></span></dt><dd>yes</dd><dt><a id="iss232"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss232.html" target="_top">MACRO-SUBFORMS-TOP-LEVEL-P:ADD-CONSTRAINTS</a></span></dt><dd>no</dd><dt><a id="iss233"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss233.html" target="_top">MACROEXPAND-HOOK-DEFAULT:EXPLICITLY-VAGUE</a></span></dt><dd>yes</dd><dt><a id="iss234"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss234.html" target="_top">MACROEXPAND-HOOK-INITIAL-VALUE:IMPLEMENTATION-DEPENDENT</a></span></dt><dd>yes</dd><dt><a id="iss235"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss235.html" target="_top">MACROEXPAND-RETURN-VALUE:TRUE</a></span></dt><dd>yes</dd><dt><a id="iss236"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss236.html" target="_top">MAKE-LOAD-FORM-CONFUSION:REWRITE</a></span></dt><dd>yes</dd><dt><a id="iss237"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss237.html" target="_top">MAKE-LOAD-FORM-SAVING-SLOTS:NO-INITFORMS</a></span></dt><dd>yes</dd><dt><a id="iss238"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss238.html" target="_top">MAKE-PACKAGE-USE-DEFAULT:IMPLEMENTATION-DEPENDENT</a></span></dt><dd>yes</dd><dt><a id="iss239"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss239.html" target="_top">MAP-INTO:ADD-FUNCTION</a></span></dt><dd>yes</dd><dt><a id="iss240"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss240.html" target="_top">MAPPING-DESTRUCTIVE-INTERACTION:EXPLICITLY-VAGUE</a></span></dt><dd>yes</dd><dt><a id="iss241"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss241.html" target="_top">METACLASS-OF-SYSTEM-CLASS:UNSPECIFIED</a></span></dt><dd>yes</dd><dt><a id="iss242"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss242.html" target="_top">METHOD-COMBINATION-ARGUMENTS:CLARIFY</a></span></dt><dd>no</dd><dt><a id="iss243"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss243.html" target="_top">METHOD-INITFORM:FORBID-CALL-NEXT-METHOD</a></span></dt><dd>no</dd><dt><a id="iss244"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss244.html" target="_top">MUFFLE-WARNING-CONDITION-ARGUMENT</a></span></dt><dd>yes</dd><dt><a id="iss245"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss245.html" target="_top">MULTIPLE-VALUE-SETQ-ORDER:LIKE-SETF-OF-VALUES</a></span></dt><dd>yes</dd><dt><a id="iss246"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss246.html" target="_top">MULTIPLE-VALUES-LIMIT-ON-VARIABLES:UNDEFINED</a></span></dt><dd>yes</dd><dt><a id="iss247"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss247.html" target="_top">NINTERSECTION-DESTRUCTION</a></span></dt><dd>yes</dd><dt><a id="iss248"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss248.html" target="_top">NINTERSECTION-DESTRUCTION:REVERT</a></span></dt><dd>yes</dd><dt><a id="iss249"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss249.html" target="_top">NOT-AND-NULL-RETURN-VALUE:X3J13-MAR-93</a></span></dt><dd>yes</dd><dt><a id="iss250"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss250.html" target="_top">NTH-VALUE:ADD</a></span></dt><dd>yes</dd><dt><a id="iss251"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss251.html" target="_top">OPTIMIZE-DEBUG-INFO:NEW-QUALITY</a></span></dt><dd>yes</dd><dt><a id="iss252"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss252.html" target="_top">PACKAGE-CLUTTER:REDUCE</a></span></dt><dd>yes</dd><dt><a id="iss253"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss253.html" target="_top">PACKAGE-DELETION:NEW-FUNCTION</a></span></dt><dd>yes</dd><dt><a id="iss254"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss254.html" target="_top">PACKAGE-FUNCTION-CONSISTENCY:MORE-PERMISSIVE</a></span></dt><dd>yes</dd><dt><a id="iss255"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss255.html" target="_top">PARSE-ERROR-STREAM:SPLIT-TYPES</a></span></dt><dd>yes</dd><dt><a id="iss256"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss256.html" target="_top">PATHNAME-COMPONENT-CASE:KEYWORD-ARGUMENT</a></span></dt><dd>yes</dd><dt><a id="iss257"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss257.html" target="_top">PATHNAME-COMPONENT-VALUE:SPECIFY</a></span></dt><dd>no</dd><dt><a id="iss258"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss258.html" target="_top">PATHNAME-HOST-PARSING:RECOGNIZE-LOGICAL-HOST-NAMES</a></span></dt><dd>yes when <a class="link" href="#parsename" title="19.5.3. Function PARSE-NAMESTRING"><code class="varname">CUSTOM:*PARSE-NAMESTRING-ANSI*</code></a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
 </dd><dt><a id="iss259"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss259.html" target="_top">PATHNAME-LOGICAL:ADD</a></span></dt><dd>yes</dd><dt><a id="iss260"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss260.html" target="_top">PATHNAME-PRINT-READ:SHARPSIGN-P</a></span></dt><dd>yes</dd><dt><a id="iss261"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss261.html" target="_top">PATHNAME-STREAM</a></span></dt><dd>yes</dd><dt><a id="iss262"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss262.html" target="_top">PATHNAME-STREAM:FILES-OR-SYNONYM</a></span></dt><dd>yes</dd><dt><a id="iss263"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss263.html" target="_top">PATHNAME-SUBDIRECTORY-LIST:NEW-REPRESENTATION</a></span></dt><dd>yes</dd><dt><a id="iss264"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss264.html" target="_top">PATHNAME-SYMBOL</a></span></dt><dd>yes when <a class="link" href="#parsename" title="19.5.3. Function PARSE-NAMESTRING"><code class="varname">CUSTOM:*PARSE-NAMESTRING-ANSI*</code></a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
 </dd><dt><a id="iss265"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss265.html" target="_top">PATHNAME-SYNTAX-ERROR-TIME:EXPLICITLY-VAGUE</a></span></dt><dd>yes</dd><dt><a id="iss266"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss266.html" target="_top">PATHNAME-UNSPECIFIC-COMPONENT:NEW-TOKEN</a></span></dt><dd>yes</dd><dt><a id="iss267"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss267.html" target="_top">PATHNAME-WILD:NEW-FUNCTIONS</a></span></dt><dd>yes</dd><dt><a id="iss268"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss268.html" target="_top">PEEK-CHAR-READ-CHAR-ECHO:FIRST-READ-CHAR</a></span></dt><dd>yes</dd><dt><a id="iss269"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss269.html" target="_top">PLIST-DUPLICATES:ALLOW</a></span></dt><dd>yes</dd><dt><a id="iss270"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss270.html" target="_top">PRETTY-PRINT-INTERFACE</a></span></dt><dd>yes</dd><dt><a id="iss271"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss271.html" target="_top">PRINC-READABLY:X3J13-DEC-91</a></span></dt><dd>yes</dd><dt><a id="iss272"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss272.html" target="_top">PRINT-CASE-BEHAVIOR:CLARIFY</a></span></dt><dd>yes</dd><dt><a id="iss273"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss273.html" target="_top">PRINT-CASE-PRINT-ESCAPE-INTERACTION:VERTICAL-BAR-RULE-NO-UPCASE</a></span></dt><dd>yes</dd><dt><a id="iss274"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss274.html" target="_top">PRINT-CIRCLE-SHARED:RESPECT-PRINT-CIRCLE</a></span></dt><dd>yes</dd><dt><a id="iss275"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss275.html" target="_top">PRINT-CIRCLE-STRUCTURE:USER-FUNCTIONS-WORK</a></span></dt><dd>yes</dd><dt><a id="iss276"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss276.html" target="_top">PRINT-READABLY-BEHAVIOR:CLARIFY</a></span></dt><dd>yes</dd><dt><a id="iss277"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss277.html" target="_top">PRINTER-WHITESPACE:JUST-ONE-SPACE</a></span></dt><dd>yes</dd><dt><a id="iss278"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss278.html" target="_top">PROCLAIM-ETC-IN-COMPILE-FILE:NEW-MACRO</a></span></dt><dd>yes</dd><dt><a id="iss279"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss279.html" target="_top">PUSH-EVALUATION-ORDER:FIRST-ITEM</a></span></dt><dd>yes</dd><dt><a id="iss280"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss280.html" target="_top">PUSH-EVALUATION-ORDER:ITEM-FIRST</a></span></dt><dd>yes</dd><dt><a id="iss281"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss281.html" target="_top">PUSHNEW-STORE-REQUIRED:UNSPECIFIED</a></span></dt><dd>yes</dd><dt><a id="iss282"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss282.html" target="_top">QUOTE-SEMANTICS:NO-COPYING</a></span></dt><dd>yes</dd><dt><a id="iss283"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss283.html" target="_top">RANGE-OF-COUNT-KEYWORD:NIL-OR-INTEGER</a></span></dt><dd>yes, when <a class="link" href="#count-ansi" title="Variable CUSTOM:*SEQUENCE-COUNT-ANSI*"><code class="varname">CUSTOM:*SEQUENCE-COUNT-ANSI*</code></a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>;
    otherwise negative <code class="constant">:COUNT</code> values are not allowed.
 </dd><dt><a id="iss284"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss284.html" target="_top">RANGE-OF-START-AND-END-PARAMETERS:INTEGER-AND-INTEGER-NIL</a></span></dt><dd>yes</dd><dt><a id="iss285"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss285.html" target="_top">READ-AND-WRITE-BYTES:NEW-FUNCTIONS</a></span></dt><dd>yes</dd><dt><a id="iss286"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss286.html" target="_top">READ-CASE-SENSITIVITY:READTABLE-KEYWORDS</a></span></dt><dd>yes</dd><dt><a id="iss287"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss287.html" target="_top">READ-MODIFY-WRITE-EVALUATION-ORDER:DELAYED-ACCESS-STORES</a></span></dt><dd>no</dd><dt><a id="iss288"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss288.html" target="_top">READ-SUPPRESS-CONFUSING:GENERALIZE</a></span></dt><dd>yes, except that <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-delimited-list.html" target="_top"><code class="function">READ-DELIMITED-LIST</code></a> still
    constructs a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a></dd><dt><a id="iss289"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss289.html" target="_top">READER-ERROR:NEW-TYPE</a></span></dt><dd>yes</dd><dt><a id="iss290"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss290.html" target="_top">REAL-NUMBER-TYPE:X3J13-MAR-89</a></span></dt><dd>yes</dd><dt><a id="iss291"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss291.html" target="_top">RECURSIVE-DEFTYPE:EXPLICITLY-VAGUE</a></span></dt><dd>yes</dd><dt><a id="iss292"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss292.html" target="_top">REDUCE-ARGUMENT-EXTRACTION</a></span></dt><dd>yes</dd><dt><a id="iss293"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss293.html" target="_top">REMF-DESTRUCTION-UNSPECIFIED:X3J13-MAR-89</a></span></dt><dd>yes</dd><dt><a id="iss294"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss294.html" target="_top">REQUIRE-PATHNAME-DEFAULTS-AGAIN:X3J13-DEC-91</a></span></dt><dd>yes</dd><dt><a id="iss295"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss295.html" target="_top">REQUIRE-PATHNAME-DEFAULTS-YET-AGAIN:RESTORE-ARGUMENT</a></span></dt><dd>yes</dd><dt><a id="iss296"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss296.html" target="_top">REQUIRE-PATHNAME-DEFAULTS:ELIMINATE</a></span></dt><dd>superseded by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss294.html" target="_top">REQUIRE-PATHNAME-DEFAULTS-AGAIN:X3J13-DEC-91</a></dd><dt><a id="iss297"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss297.html" target="_top">REST-LIST-ALLOCATION:MAY-SHARE</a></span></dt><dd>yes</dd><dt><a id="iss298"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss298.html" target="_top">RESULT-LISTS-SHARED:SPECIFY</a></span></dt><dd>yes</dd><dt><a id="iss299"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss299.html" target="_top">RETURN-VALUES-UNSPECIFIED:SPECIFY</a></span></dt><dd>yes</dd><dt><a id="iss300"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss300.html" target="_top">ROOM-DEFAULT-ARGUMENT:NEW-VALUE</a></span></dt><dd>yes</dd><dt><a id="iss301"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss301.html" target="_top">SELF-MODIFYING-CODE:FORBID</a></span></dt><dd>yes</dd><dt><a id="iss302"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss302.html" target="_top">SEQUENCE-TYPE-LENGTH:MUST-MATCH</a></span></dt><dd>yes</dd><dt><a id="iss303"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss303.html" target="_top">SETF-APPLY-EXPANSION:IGNORE-EXPANDER</a></span></dt><dd>yes</dd><dt><a id="iss304"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss304.html" target="_top">SETF-FIND-CLASS:ALLOW-NIL</a></span></dt><dd>yes</dd><dt><a id="iss305"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss305.html" target="_top">SETF-FUNCTIONS-AGAIN:MINIMAL-CHANGES</a></span></dt><dd>yes</dd><dt><a id="iss306"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss306.html" target="_top">SETF-GET-DEFAULT:EVALUATED-BUT-IGNORED</a></span></dt><dd>yes</dd><dt><a id="iss307"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss307.html" target="_top">SETF-MACRO-EXPANSION:LAST</a></span></dt><dd>yes</dd><dt><a id="iss308"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss308.html" target="_top">SETF-METHOD-VS-SETF-METHOD:RENAME-OLD-TERMS</a></span></dt><dd>yes</dd><dt><a id="iss309"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss309.html" target="_top">SETF-MULTIPLE-STORE-VARIABLES:ALLOW</a></span></dt><dd>yes</dd><dt><a id="iss310"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss310.html" target="_top">SETF-OF-APPLY:ONLY-AREF-AND-FRIENDS</a></span></dt><dd>yes</dd><dt><a id="iss311"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss311.html" target="_top">SETF-OF-VALUES:ADD</a></span></dt><dd>yes</dd><dt><a id="iss312"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss312.html" target="_top">SETF-SUB-METHODS:DELAYED-ACCESS-STORES</a></span></dt><dd>yes</dd><dt><a id="iss313"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss313.html" target="_top">SHADOW-ALREADY-PRESENT</a></span></dt><dd>yes</dd><dt><a id="iss314"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss314.html" target="_top">SHADOW-ALREADY-PRESENT:WORKS</a></span></dt><dd>yes</dd><dt><a id="iss315"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss315.html" target="_top">SHARP-COMMA-CONFUSION:REMOVE</a></span></dt><dd>no</dd><dt><a id="iss316"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss316.html" target="_top">SHARP-O-FOOBAR:CONSEQUENCES-UNDEFINED</a></span></dt><dd>yes</dd><dt><a id="iss317"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss317.html" target="_top">SHARP-STAR-DELIMITER:NORMAL-DELIMITER</a></span></dt><dd>yes</dd><dt><a id="iss318"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss318.html" target="_top">SHARPSIGN-PLUS-MINUS-PACKAGE:KEYWORD</a></span></dt><dd>yes</dd><dt><a id="iss319"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss319.html" target="_top">SLOT-MISSING-VALUES:SPECIFY</a></span></dt><dd>yes</dd><dt><a id="iss320"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss320.html" target="_top">SLOT-VALUE-METACLASSES:LESS-MINIMAL</a></span></dt><dd>yes</dd><dt><a id="iss321"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss321.html" target="_top">SPECIAL-FORM-P-MISNOMER:RENAME</a></span></dt><dd>yes</dd><dt><a id="iss322"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss322.html" target="_top">SPECIAL-TYPE-SHADOWING:CLARIFY</a></span></dt><dd>yes</dd><dt><a id="iss323"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss323.html" target="_top">STANDARD-INPUT-INITIAL-BINDING:DEFINED-CONTRACTS</a></span></dt><dd>yes</dd><dt><a id="iss324"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss324.html" target="_top">STANDARD-REPERTOIRE-GRATUITOUS:RENAME</a></span></dt><dd>yes</dd><dt><a id="iss325"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss325.html" target="_top">STEP-ENVIRONMENT:CURRENT</a></span></dt><dd>yes</dd><dt><a id="iss326"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss326.html" target="_top">STEP-MINIMAL:PERMIT-PROGN</a></span></dt><dd>yes</dd><dt><a id="iss327"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss327.html" target="_top">STREAM-ACCESS:ADD-TYPES-ACCESSORS</a></span></dt><dd>yes</dd><dt><a id="iss328"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss328.html" target="_top">STREAM-CAPABILITIES:INTERACTIVE-STREAM-P</a></span></dt><dd>yes</dd><dt><a id="iss329"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss329.html" target="_top">STRING-COERCION:MAKE-CONSISTENT</a></span></dt><dd>yes</dd><dt><a id="iss330"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss330.html" target="_top">STRING-OUTPUT-STREAM-BASHING:UNDEFINED</a></span></dt><dd>yes</dd><dt><a id="iss331"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss331.html" target="_top">STRUCTURE-READ-PRINT-SYNTAX:KEYWORDS</a></span></dt><dd>yes</dd><dt><a id="iss332"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss332.html" target="_top">SUBSEQ-OUT-OF-BOUNDS</a></span></dt><dd>yes</dd><dt><a id="iss333"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss333.html" target="_top">SUBSEQ-OUT-OF-BOUNDS:IS-AN-ERROR</a></span></dt><dd>yes</dd><dt><a id="iss334"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss334.html" target="_top">SUBSETTING-POSITION:NONE</a></span></dt><dd>yes</dd><dt><a id="iss335"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss335.html" target="_top">SUBTYPEP-ENVIRONMENT:ADD-ARG</a></span></dt><dd>yes</dd><dt><a id="iss336"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss336.html" target="_top">SUBTYPEP-TOO-VAGUE:CLARIFY-MORE</a></span></dt><dd>yes</dd><dt><a id="iss337"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss337.html" target="_top">SXHASH-DEFINITION:SIMILAR-FOR-SXHASH</a></span></dt><dd>yes</dd><dt><a id="iss338"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss338.html" target="_top">SYMBOL-MACROLET-DECLARE:ALLOW</a></span></dt><dd>yes</dd><dt><a id="iss339"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss339.html" target="_top">SYMBOL-MACROLET-SEMANTICS:SPECIAL-FORM</a></span></dt><dd>yes</dd><dt><a id="iss340"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss340.html" target="_top">SYMBOL-MACROLET-TYPE-DECLARATION:NO</a></span></dt><dd>yes</dd><dt><a id="iss341"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss341.html" target="_top">SYMBOL-MACROS-AND-PROCLAIMED-SPECIALS:SIGNALS-AN-ERROR</a></span></dt><dd>yes</dd><dt><a id="iss342"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss342.html" target="_top">SYMBOL-PRINT-ESCAPE-BEHAVIOR:CLARIFY</a></span></dt><dd>yes</dd><dt><a id="iss343"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss343.html" target="_top">SYNTACTIC-ENVIRONMENT-ACCESS:RETRACTED-MAR91</a></span></dt><dd>yes</dd><dt><a id="iss344"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss344.html" target="_top">TAGBODY-TAG-EXPANSION:NO</a></span></dt><dd>yes</dd><dt><a id="iss345"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss345.html" target="_top">TAILP-NIL:T</a></span></dt><dd>yes</dd><dt><a id="iss346"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss346.html" target="_top">TEST-NOT-IF-NOT:FLUSH-ALL</a></span></dt><dd>yes, but no warning</dd><dt><a id="iss347"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss347.html" target="_top">THE-AMBIGUITY:FOR-DECLARATION</a></span></dt><dd>yes</dd><dt><a id="iss348"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss348.html" target="_top">THE-VALUES:RETURN-NUMBER-RECEIVED</a></span></dt><dd>yes</dd><dt><a id="iss349"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss349.html" target="_top">TIME-ZONE-NON-INTEGER:ALLOW</a></span></dt><dd>yes</dd><dt><a id="iss350"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss350.html" target="_top">TYPE-DECLARATION-ABBREVIATION:ALLOW-ALL</a></span></dt><dd>no</dd><dt><a id="iss351"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss351.html" target="_top">TYPE-OF-AND-PREDEFINED-CLASSES:TYPE-OF-HANDLES-FLOATS</a></span></dt><dd>yes</dd><dt><a id="iss352"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss352.html" target="_top">TYPE-OF-AND-PREDEFINED-CLASSES:UNIFY-AND-EXTEND</a></span></dt><dd>yes</dd><dt><a id="iss353"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss353.html" target="_top">TYPE-OF-UNDERCONSTRAINED:ADD-CONSTRAINTS</a></span></dt><dd>yes</dd><dt><a id="iss354"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss354.html" target="_top">TYPE-SPECIFIER-ABBREVIATION:X3J13-JUN90-GUESS</a></span></dt><dd>yes</dd><dt><a id="iss355"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss355.html" target="_top">UNDEFINED-VARIABLES-AND-FUNCTIONS:COMPROMISE</a></span></dt><dd>yes</dd><dt><a id="iss356"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss356.html" target="_top">UNINITIALIZED-ELEMENTS:CONSEQUENCES-UNDEFINED</a></span></dt><dd>yes, could add error checking
 </dd><dt><a id="iss357"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss357.html" target="_top">UNREAD-CHAR-AFTER-PEEK-CHAR:DONT-ALLOW</a></span></dt><dd>yes</dd><dt><a id="iss358"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss358.html" target="_top">UNSOLICITED-MESSAGES:NOT-TO-SYSTEM-USER-STREAMS</a></span></dt><dd>yes</dd><dt><a id="iss359"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss359.html" target="_top">VARIABLE-LIST-ASYMMETRY:SYMMETRIZE</a></span></dt><dd>yes</dd><dt><a id="iss360"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss360.html" target="_top">WITH-ADDED-METHODS:DELETE</a></span></dt><dd>yes</dd><dt><a id="iss361"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss361.html" target="_top">WITH-COMPILATION-UNIT:NEW-MACRO</a></span></dt><dd>yes</dd><dt><a id="iss362"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss362.html" target="_top">WITH-OPEN-FILE-DOES-NOT-EXIST:STREAM-IS-NIL</a></span></dt><dd>yes</dd><dt><a id="iss363"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss363.html" target="_top">WITH-OPEN-FILE-SETQ:EXPLICITLY-VAGUE</a></span></dt><dd>yes</dd><dt><a id="iss364"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss364.html" target="_top">WITH-OPEN-FILE-STREAM-EXTENT:DYNAMIC-EXTENT</a></span></dt><dd>yes</dd><dt><a id="iss365"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss365.html" target="_top">WITH-OUTPUT-TO-STRING-APPEND-STYLE:VECTOR-PUSH-EXTEND</a></span></dt><dd>yes</dd><dt><a id="iss366"></a><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss366.html" target="_top">WITH-STANDARD-IO-SYNTAX-READTABLE:X3J13-MAR-91</a></span></dt><dd>yes</dd></dl></div></div></div><div class="part"><div class="titlepage"><div><div><h1 class="title"><a id="ext-standard"></a>Part II. Common Portable Extensions</h1></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="chapter"><a href="#mop-chap">29. Meta-Object Protocol</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-intro">29.1. Introduction</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-intro-notation">29.1.1. Notation</a></span></dt><dt><span class="section"><a href="#mop-package">29.1.2. Package</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-overview">29.2. Overview</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-metaobjects">29.2.1. Metaobjects</a></span></dt><dt><span class="section"><a href="#mop-mo-cl-inheritance">29.2.2. Inheritance Structure of Metaobject Classes</a></span></dt><dt><span class="section"><a href="#mop-ui-macro">29.2.3. Processing of the User Interface Macros</a></span></dt><dt><span class="section"><a href="#mop-ov-mo-init">29.2.4. Metaobject Initialization Protocol</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-classes">29.3. Classes</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-cl-defclass">29.3.1. Macro <code class="function">DEFCLASS</code></a></span></dt><dt><span class="section"><a href="#mop-cl-Inheritance">29.3.2. Inheritance Structure of class metaobject Classes</a></span></dt><dt><span class="section"><a href="#mop-cl-readers">29.3.3. Introspection: Readers for class metaobjects</a></span></dt><dt><span class="section"><a href="#mop-cl-finalization">29.3.4. Class Finalization Protocol</a></span></dt><dt><span class="section"><a href="#mop-cl-init">29.3.5. Class Initialization</a></span></dt><dt><span class="section"><a href="#mop-cl-customize">29.3.6. Customization</a></span></dt><dt><span class="section"><a href="#mop-cl-dep">29.3.7. Updating Dependencies</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-sd">29.4. Slot Definitions</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-sd-inheritance">29.4.1. Inheritance Structure of slot definition metaobject Classes</a></span></dt><dt><span class="section"><a href="#mop-sd-readers">29.4.2. Introspection: Readers for slot definition metaobjects</a></span></dt><dt><span class="section"><a href="#mop-sd-init">29.4.3. Initialization of slot definition metaobjects</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-gf">29.5. Generic Functions</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-gf-inheritance">29.5.1. Inheritance Structure of generic function metaobject Classes</a></span></dt><dt><span class="section"><a href="#mop-gf-readers">29.5.2. Introspection: Readers for generic function metaobjects</a></span></dt><dt><span class="section"><a href="#mop-gf-init">29.5.3. Initialization of Generic Functions</a></span></dt><dt><span class="section"><a href="#mop-gf-customize">29.5.4. Customization</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-meth">29.6. Methods</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-meth-inheritance">29.6.1. Inheritance Structure of method metaobject Classes</a></span></dt><dt><span class="section"><a href="#mop-meth-mo-readers">29.6.2. Introspection: Readers for method metaobjects</a></span></dt><dt><span class="section"><a href="#mop-meth-init">29.6.3. Initialization of Methods</a></span></dt><dt><span class="section"><a href="#mop-meth-customize">29.6.4. Customization</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-accessors">29.7. Accessor Methods</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-acc-readers">29.7.1. Introspection</a></span></dt><dt><span class="section"><a href="#mop-acc-customize">29.7.2. Customization</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-specializers">29.8. Specializers</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-specializers-inheritance">29.8.1. Inheritance Structure of Specializer Metaobject Classes</a></span></dt><dt><span class="section"><a href="#mop-spec-readers">29.8.2. Introspection</a></span></dt><dt><span class="section"><a href="#mop-spec-init">29.8.3. Initialization</a></span></dt><dt><span class="section"><a href="#mop-spec-dep">29.8.4. Updating Dependencies</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-meth-comb">29.9. Method Combinations</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-meth-comb-inheritance">29.9.1. Inheritance Structure of method combination metaobject Classes</a></span></dt><dt><span class="section"><a href="#mop-meth-comb-customize">29.9.2. Customization</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-slot-access">29.10. Slot Access</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-sa-instance-struct">29.10.1. Instance Structure Protocol</a></span></dt><dt><span class="section"><a href="#mop-sa-funcallable">29.10.2. Funcallable Instances</a></span></dt><dt><span class="section"><a href="#mop-sa-customize">29.10.3. Customization</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-dep-maint">29.11. Dependent Maintenance</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-dep-maint-protocol">29.11.1. Protocol</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-clisp">29.12. Deviations from AMOP</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-clisp-warn">29.12.1. Warning <code class="classname">CLOS:CLOS-WARNING</code></a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="#gray">30. Gray streams</a></span></dt><dd><dl><dt><span class="section"><a href="#gray-overview">30.1. Overview</a></span></dt><dt><span class="section"><a href="#gray-classes">30.2. Defined classes</a></span></dt><dt><span class="section"><a href="#gray-gf-general">30.3. General generic functions</a></span></dt><dt><span class="section"><a href="#gray-gf-char-in">30.4. Generic functions for character input</a></span></dt><dt><span class="section"><a href="#gray-gf-char-out">30.5. Generic functions for character output</a></span></dt><dt><span class="section"><a href="#gray-gf-byte-in">30.6. Generic functions for binary input</a></span></dt><dt><span class="section"><a href="#gray-gf-byte-out">30.7. Generic functions for binary output</a></span></dt><dt><span class="section"><a href="#fill-stream">30.8. Class <code class="classname">EXT:FILL-STREAM</code></a></span></dt></dl></dd></dl></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="mop-chap"></a>Chapter 29. Meta-Object Protocol</h2></div><div><h3 class="subtitle"><em>Adapted from chapters 5 and 6 of [<span class="citation"><a class="link" href="#amop" title="The Art of the Metaobject Protocol">AMOP</a></span>]</em></h3></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#mop-intro">29.1. Introduction</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-intro-notation">29.1.1. Notation</a></span></dt><dt><span class="section"><a href="#mop-package">29.1.2. Package</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-overview">29.2. Overview</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-metaobjects">29.2.1. Metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-mo-classes">29.2.1.1. Classes</a></span></dt><dt><span class="section"><a href="#mop-mo-slot-defs">29.2.1.2. Slot Definitions</a></span></dt><dt><span class="section"><a href="#mop-mo-gen-funs">29.2.1.3. Generic Functions</a></span></dt><dt><span class="section"><a href="#mop-mo-methods">29.2.1.4. Methods</a></span></dt><dt><span class="section"><a href="#mop-mo-spec">29.2.1.5. Specializers</a></span></dt><dt><span class="section"><a href="#mop-mo-meth-combs">29.2.1.6. Method Combinations</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-mo-cl-inheritance">29.2.2. Inheritance Structure of Metaobject Classes</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-ov-impl-and-user-spec">29.2.2.1. Implementation and User Specialization</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-ui-macro">29.2.3. Processing of the User Interface Macros</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-compile-ui-macro">29.2.3.1. Compile-file Processing of the User Interface Macros</a></span></dt><dt><span class="section"><a href="#mop-ov-ui-others">29.2.3.2. Compile-file Processing of Specific User Interface Macros</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-ov-mo-init">29.2.4. Metaobject Initialization Protocol</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-classes">29.3. Classes</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-cl-defclass">29.3.1. Macro <code class="function">DEFCLASS</code></a></span></dt><dt><span class="section"><a href="#mop-cl-Inheritance">29.3.2. Inheritance Structure of class metaobject Classes</a></span></dt><dt><span class="section"><a href="#mop-cl-readers">29.3.3. Introspection: Readers for class metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#class-name">29.3.3.1. Generic Function <code class="function">CLASS-NAME</code></a></span></dt><dt><span class="section"><a href="#class-direct-superclasses">29.3.3.2. Generic Function <code class="function">CLOS:CLASS-DIRECT-SUPERCLASSES</code></a></span></dt><dt><span class="section"><a href="#class-direct-slots">29.3.3.3. Generic Function <code class="function">CLOS:CLASS-DIRECT-SLOTS</code></a></span></dt><dt><span class="section"><a href="#class-direct-default-initargs">29.3.3.4. Generic Function <code class="function">CLOS:CLASS-DIRECT-DEFAULT-INITARGS</code></a></span></dt><dt><span class="section"><a href="#cpl">29.3.3.5. Generic Function <code class="function">CLOS:CLASS-PRECEDENCE-LIST</code></a></span></dt><dt><span class="section"><a href="#class-direct-subclasses">29.3.3.6. Generic Function <code class="function">CLOS:CLASS-DIRECT-SUBCLASSES</code></a></span></dt><dt><span class="section"><a href="#class-slots">29.3.3.7. Generic Function <code class="function">CLOS:CLASS-SLOTS</code></a></span></dt><dt><span class="section"><a href="#class-default-initargs">29.3.3.8. Generic Function <code class="function">CLOS:CLASS-DEFAULT-INITARGS</code></a></span></dt><dt><span class="section"><a href="#class-finalized-p">29.3.3.9. Generic Function <code class="function">CLOS:CLASS-FINALIZED-P</code></a></span></dt><dt><span class="section"><a href="#class-prototype">29.3.3.10. Generic Function <code class="function">CLOS:CLASS-PROTOTYPE</code></a></span></dt><dt><span class="section"><a href="#mop-cl-readers-methods">29.3.3.11. Methods</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-cl-finalization">29.3.4. Class Finalization Protocol</a></span></dt><dt><span class="section"><a href="#mop-cl-init">29.3.5. Class Initialization</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-cl-init-mo">29.3.5.1. Initialization of class metaobjects</a></span></dt><dt><span class="section"><a href="#mop-cl-reinit-mo">29.3.5.2. Reinitialization of class metaobjects</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-cl-customize">29.3.6. Customization</a></span></dt><dd><dl><dt><span class="section"><a href="#setf-class-name">29.3.6.1. Generic Function <code class="code">(SETF CLASS-NAME)</code></a></span></dt><dt><span class="section"><a href="#ensure-class">29.3.6.2. Generic Function <code class="function">CLOS:ENSURE-CLASS</code></a></span></dt><dt><span class="section"><a href="#ensure-class-UC">29.3.6.3. Generic Function <code class="function">CLOS:ENSURE-CLASS-USING-CLASS</code></a></span></dt><dt><span class="section"><a href="#finalize-inheritance">29.3.6.4. Generic Function <code class="function">CLOS:FINALIZE-INHERITANCE</code></a></span></dt><dt><span class="section"><a href="#mop-make-instance">29.3.6.5. Generic Function <code class="function">MAKE-INSTANCE</code></a></span></dt><dt><span class="section"><a href="#alloc-instance">29.3.6.6. Generic Function <code class="function">ALLOCATE-INSTANCE</code></a></span></dt><dt><span class="section"><a href="#validate-superclass">29.3.6.7. Generic Function <code class="function">CLOS:VALIDATE-SUPERCLASS</code></a></span></dt><dt><span class="section"><a href="#compute-dsd-initargs">29.3.6.8. Generic Function <code class="function">CLOS:COMPUTE-DIRECT-SLOT-DEFINITION-INITARGS</code></a></span></dt><dt><span class="section"><a href="#dsd-class">29.3.6.9. Generic Function <code class="function">CLOS:DIRECT-SLOT-DEFINITION-CLASS</code></a></span></dt><dt><span class="section"><a href="#compute-cpl">29.3.6.10. Generic Function <code class="function">CLOS:COMPUTE-CLASS-PRECEDENCE-LIST</code></a></span></dt><dt><span class="section"><a href="#compute-slots">29.3.6.11. Generic Function <code class="function">CLOS:COMPUTE-SLOTS</code></a></span></dt><dt><span class="section"><a href="#compute-esd">29.3.6.12. Generic Function <code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION</code></a></span></dt><dt><span class="section"><a href="#compute-esd-initargs">29.3.6.13. Generic Function <code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION-INITARGS</code></a></span></dt><dt><span class="section"><a href="#esd-class">29.3.6.14. Generic Function <code class="function">CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS</code></a></span></dt><dt><span class="section"><a href="#compute-default-initargs">29.3.6.15. Generic Function <code class="function">CLOS:COMPUTE-DEFAULT-INITARGS</code></a></span></dt></dl></dd><dt><span class="section"><a href="#mop-cl-dep">29.3.7. Updating Dependencies</a></span></dt><dd><dl><dt><span class="section"><a href="#add-direct-subclass">29.3.7.1. Generic Function <code class="function">CLOS:ADD-DIRECT-SUBCLASS</code></a></span></dt><dt><span class="section"><a href="#remove-direct-subclass">29.3.7.2. Generic Function <code class="function">CLOS:REMOVE-DIRECT-SUBCLASS</code></a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="#mop-sd">29.4. Slot Definitions</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-sd-inheritance">29.4.1. Inheritance Structure of slot definition metaobject Classes</a></span></dt><dt><span class="section"><a href="#mop-sd-readers">29.4.2. Introspection: Readers for slot definition metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-sd-readers-GFs">29.4.2.1. Generic Functions</a></span></dt><dt><span class="section"><a href="#slotd-mo-readers-methods">29.4.2.2. Methods</a></span></dt><dt><span class="section"><a href="#slotd-mo-readers-dsd">29.4.2.3. Readers for direct slot definition metaobjects</a></span></dt><dt><span class="section"><a href="#slotd-mo-readers-esd">29.4.2.4. Readers for effective slot definition metaobjects</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-sd-init">29.4.3. Initialization of slot definition metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#slotdef-mo-methods">29.4.3.1. Methods</a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="#mop-gf">29.5. Generic Functions</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-gf-inheritance">29.5.1. Inheritance Structure of generic function metaobject Classes</a></span></dt><dt><span class="section"><a href="#mop-gf-readers">29.5.2. Introspection: Readers for generic function metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#gf-name">29.5.2.1. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-NAME</code></a></span></dt><dt><span class="section"><a href="#gf-methods">29.5.2.2. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-METHODS</code></a></span></dt><dt><span class="section"><a href="#gf-lambda-list">29.5.2.3. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-LAMBDA-LIST</code></a></span></dt><dt><span class="section"><a href="#gf-argument-precedence-order">29.5.2.4. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-ARGUMENT-PRECEDENCE-ORDER</code></a></span></dt><dt><span class="section"><a href="#gf-declarations">29.5.2.5. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-DECLARATIONS</code></a></span></dt><dt><span class="section"><a href="#gf-method-class">29.5.2.6. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-METHOD-CLASS</code></a></span></dt><dt><span class="section"><a href="#gf-method-combination">29.5.2.7. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-METHOD-COMBINATION</code></a></span></dt><dt><span class="section"><a href="#gf-name-methods">29.5.2.8. Methods</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-gf-init">29.5.3. Initialization of Generic Functions</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-gf-init-defgeneric">29.5.3.1. Macro <code class="function">DEFGENERIC</code></a></span></dt><dt><span class="section"><a href="#mop-gf-invocation">29.5.3.2. Generic Function Invocation Protocol</a></span></dt><dt><span class="section"><a href="#mop-gf-init-mo">29.5.3.3. Initialization of generic function metaobjects</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-gf-customize">29.5.4. Customization</a></span></dt><dd><dl><dt><span class="section"><a href="#setf-gf-name">29.5.4.1. Generic Function <code class="code">(SETF CLOS:GENERIC-FUNCTION-NAME)</code></a></span></dt><dt><span class="section"><a href="#ensure-gf">29.5.4.2. Generic Function <code class="function">ENSURE-GENERIC-FUNCTION</code></a></span></dt><dt><span class="section"><a href="#ensure-gf-UC">29.5.4.3. Generic Function <code class="function">CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS</code></a></span></dt><dt><span class="section"><a href="#mop-add-method">29.5.4.4. Generic Function <code class="function">ADD-METHOD</code></a></span></dt><dt><span class="section"><a href="#mop-remove-method">29.5.4.5. Generic Function <code class="function">REMOVE-METHOD</code></a></span></dt><dt><span class="section"><a href="#compute-applicable-methods">29.5.4.6. Generic Function <code class="function">CLOS:COMPUTE-APPLICABLE-METHODS</code></a></span></dt><dt><span class="section"><a href="#compute-applicable-methods-UC">29.5.4.7. Generic Function <code class="function">CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES</code></a></span></dt><dt><span class="section"><a href="#compute-effective-method">29.5.4.8. Generic Function <code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD</code></a></span></dt><dt><span class="section"><a href="#compute-effective-method-as-function">29.5.4.9. Function <code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD-AS-FUNCTION</code></a></span></dt><dt><span class="section"><a href="#make-method-lambda">29.5.4.10. Generic Function <code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a></span></dt><dt><span class="section"><a href="#compute-discriminating-function">29.5.4.11. Generic Function <code class="function">CLOS:COMPUTE-DISCRIMINATING-FUNCTION</code></a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="#mop-meth">29.6. Methods</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-meth-inheritance">29.6.1. Inheritance Structure of method metaobject Classes</a></span></dt><dt><span class="section"><a href="#mop-meth-mo-readers">29.6.2. Introspection: Readers for method metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#method-specializers">29.6.2.1. Generic Function <code class="function">CLOS:METHOD-SPECIALIZERS</code></a></span></dt><dt><span class="section"><a href="#method-qualifiers">29.6.2.2. Generic Function <code class="function">METHOD-QUALIFIERS</code></a></span></dt><dt><span class="section"><a href="#method-lambda-list">29.6.2.3. Generic Function <code class="function">CLOS:METHOD-LAMBDA-LIST</code></a></span></dt><dt><span class="section"><a href="#method-gf">29.6.2.4. Generic Function <code class="function">CLOS:METHOD-GENERIC-FUNCTION</code></a></span></dt><dt><span class="section"><a href="#method-function">29.6.2.5. Generic Function <code class="function">CLOS:METHOD-FUNCTION</code></a></span></dt><dt><span class="section"><a href="#mop-meth-mo-readers-methods">29.6.2.6. Methods</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-meth-init">29.6.3. Initialization of Methods</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-meth-init-defmethod">29.6.3.1. Macro <code class="function">DEFMETHOD</code></a></span></dt><dt><span class="section"><a href="#mop-meth-init-mo">29.6.3.2. Initialization of method metaobjects</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-meth-customize">29.6.4. Customization</a></span></dt><dd><dl><dt><span class="section"><a href="#extract-lambda-list">29.6.4.1. Function <code class="function">CLOS:EXTRACT-LAMBDA-LIST</code></a></span></dt><dt><span class="section"><a href="#extract-specializer-names">29.6.4.2. Function <code class="function">CLOS:EXTRACT-SPECIALIZER-NAMES</code></a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="#mop-accessors">29.7. Accessor Methods</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-acc-readers">29.7.1. Introspection</a></span></dt><dd><dl><dt><span class="section"><a href="#accessor-method-slotdef">29.7.1.1. Generic Function <code class="function">CLOS:ACCESSOR-METHOD-SLOT-DEFINITION</code></a></span></dt></dl></dd><dt><span class="section"><a href="#mop-acc-customize">29.7.2. Customization</a></span></dt><dd><dl><dt><span class="section"><a href="#reader-method-class">29.7.2.1. Generic Function <code class="function">CLOS:READER-METHOD-CLASS</code></a></span></dt><dt><span class="section"><a href="#writer-method-class">29.7.2.2. Generic Function <code class="function">CLOS:WRITER-METHOD-CLASS</code></a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="#mop-specializers">29.8. Specializers</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-specializers-inheritance">29.8.1. Inheritance Structure of Specializer Metaobject Classes</a></span></dt><dt><span class="section"><a href="#mop-spec-readers">29.8.2. Introspection</a></span></dt><dd><dl><dt><span class="section"><a href="#eql-specializer-object">29.8.2.1. Function <code class="function">CLOS:EQL-SPECIALIZER-OBJECT</code></a></span></dt></dl></dd><dt><span class="section"><a href="#mop-spec-init">29.8.3. Initialization</a></span></dt><dd><dl><dt><span class="section"><a href="#intern-eql-specializer">29.8.3.1. Function <code class="function">CLOS:INTERN-EQL-SPECIALIZER</code></a></span></dt></dl></dd><dt><span class="section"><a href="#mop-spec-dep">29.8.4. Updating Dependencies</a></span></dt><dd><dl><dt><span class="section"><a href="#specializer-direct-methods">29.8.4.1. Generic Function <code class="function">CLOS:SPECIALIZER-DIRECT-METHODS</code></a></span></dt><dt><span class="section"><a href="#specializer-direct-gfs">29.8.4.2. Generic Function <code class="function">CLOS:SPECIALIZER-DIRECT-GENERIC-FUNCTIONS</code></a></span></dt><dt><span class="section"><a href="#add-direct-method">29.8.4.3. Generic Function <code class="function">CLOS:ADD-DIRECT-METHOD</code></a></span></dt><dt><span class="section"><a href="#remove-direct-method">29.8.4.4. Generic Function <code class="function">CLOS:REMOVE-DIRECT-METHOD</code></a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="#mop-meth-comb">29.9. Method Combinations</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-meth-comb-inheritance">29.9.1. Inheritance Structure of method combination metaobject Classes</a></span></dt><dt><span class="section"><a href="#mop-meth-comb-customize">29.9.2. Customization</a></span></dt><dd><dl><dt><span class="section"><a href="#find-method-combination">29.9.2.1. Generic Function <code class="function">CLOS:FIND-METHOD-COMBINATION</code></a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="#mop-slot-access">29.10. Slot Access</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-sa-instance-struct">29.10.1. Instance Structure Protocol</a></span></dt><dt><span class="section"><a href="#mop-sa-funcallable">29.10.2. Funcallable Instances</a></span></dt><dt><span class="section"><a href="#mop-sa-customize">29.10.3. Customization</a></span></dt><dd><dl><dt><span class="section"><a href="#standard-instance-access">29.10.3.1. Function <code class="function">CLOS:STANDARD-INSTANCE-ACCESS</code></a></span></dt><dt><span class="section"><a href="#funcallable-standard-instance-access">29.10.3.2. Function <code class="function">CLOS:FUNCALLABLE-STANDARD-INSTANCE-ACCESS</code></a></span></dt><dt><span class="section"><a href="#set-fif">29.10.3.3. Function <code class="function">CLOS:SET-FUNCALLABLE-INSTANCE-FUNCTION</code></a></span></dt><dt><span class="section"><a href="#slot-value-UC">29.10.3.4. Generic Function <code class="function">CLOS:SLOT-VALUE-USING-CLASS</code></a></span></dt><dt><span class="section"><a href="#setf-slot-value-UC">29.10.3.5. Generic Function <code class="code">(SETF CLOS:SLOT-VALUE-USING-CLASS)</code></a></span></dt><dt><span class="section"><a href="#slot-boundp-UC">29.10.3.6. Generic Function <code class="function">CLOS:SLOT-BOUNDP-USING-CLASS</code></a></span></dt><dt><span class="section"><a href="#slot-makunbound-UC">29.10.3.7. Generic Function <code class="function">CLOS:SLOT-MAKUNBOUND-USING-CLASS</code></a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="#mop-dep-maint">29.11. Dependent Maintenance</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-dep-maint-protocol">29.11.1. Protocol</a></span></dt><dd><dl><dt><span class="section"><a href="#update-dependent">29.11.1.1. Generic Function <code class="function">CLOS:UPDATE-DEPENDENT</code></a></span></dt><dt><span class="section"><a href="#add-dependent">29.11.1.2. Generic Function <code class="function">CLOS:ADD-DEPENDENT</code></a></span></dt><dt><span class="section"><a href="#remove-dependent">29.11.1.3. Generic Function <code class="function">CLOS:REMOVE-DEPENDENT</code></a></span></dt><dt><span class="section"><a href="#map-dependents">29.11.1.4. Generic Function <code class="function">CLOS:MAP-DEPENDENTS</code></a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="#mop-clisp">29.12. Deviations from AMOP</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-clisp-warn">29.12.1. Warning <code class="classname">CLOS:CLOS-WARNING</code></a></span></dt><dd><dl><dt><span class="section"><a href="#mop-clisp-gf-already-called-warning">29.12.1.1. Warning   <code class="classname">CLOS:GF-ALREADY-CALLED-WARNING</code></a></span></dt><dt><span class="section"><a href="#mop-clisp-gf-replacing-method-warning">29.12.1.2. Warning   <code class="classname">CLOS:GF-REPLACING-METHOD-WARNING</code></a></span></dt><dt><span class="section"><a href="#class-obsolescence-warning">29.12.1.3. Warning   <code class="classname">CLOS:CLASS-OBSOLESCENCE-WARNING</code></a></span></dt></dl></dd></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="mop-intro"></a>29.1. Introduction</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-intro-notation">29.1.1. Notation</a></span></dt><dt><span class="section"><a href="#mop-package">29.1.2. Package</a></span></dt></dl></div><p>The <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> specification ([<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] Chanpter 7) describes the
standard Programmer Interface for the <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> Object System (<a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a>).  This
document extends that specification by defining a metaobject protocol
for <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> - that is, a description of <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> itself as an extensible
<a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> program.  In this description, the fundamental elements of <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a>
programs (classes, slot definitions, generic functions, methods,
specializers and method combinations) are represented by first-class
objects.  The behavior of <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> is provided by these objects, or, more
precisely, by methods specialized to the classes of these objects.
</p><p>Because these objects represent pieces of <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> programs, and
because their behavior provides the behavior of the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> language
itself, they are considered meta-level objects or metaobjects.  The
protocol followed by the metaobjects to provide the behavior of <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a>
is called the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> <span class="quote">“<span class="quote">Metaobject Protocol</span>”</span> (MOP).</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-intro-notation"></a>29.1.1. Notation</h3></div></div></div><p>The description of functions follows the same form as used in the
<a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> specification.  The description of generic functions is similar
to that in the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> specification, but some minor changes have been
made in the way methods are presented.</p><p>The following is an example of the format for the syntax
description of a generic function:
</p><pre class="programlisting">
(<code class="function">gf1</code> <em class="replaceable"><code>x</code></em> <em class="replaceable"><code>y</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>v</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <em class="replaceable"><code>k</code></em>)
</pre><p>This description indicates that <code class="function">gf1</code> is a
generic function with two required parameters, <em class="replaceable"><code>x</code></em> and <em class="replaceable"><code>y</code></em>, an
optional parameter <em class="replaceable"><code>v</code></em> and a keyword parameter <em class="replaceable"><code>k</code></em>.</p><p>The description of a generic function includes a description of
its behavior.  This provides the general behavior, or protocol of the
generic function.  All methods defined on the generic function, both
portable and specified, must have behavior consistent with this
description.</p><p>Every generic function described here is an instance of the class
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a> and uses the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_7-6-6-2.html" target="_top"><code class="function">STANDARD</code></a> method
combination.</p><p>The description of a generic function also includes descriptions
of the specified methods for that generic function.  In the description
of these methods, a <strong class="first"><em class="firstterm">method signature</em></strong> is used to
describe the parameters and parameter specializers of each method. The
following is an example of the format for a method signature:
</p><pre class="programlisting">
<span class="method"><code class="literal">(<code class="function">gf1</code> (<em class="replaceable"><code>x</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>) <em class="replaceable"><code>y</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>v</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <em class="replaceable"><code>k</code></em>)</code></span>
</pre><p>This signature indicates that this primary method on the generic
function <code class="function">gf1</code> has two required parameters, named
<em class="replaceable"><code>x</code></em> and <em class="replaceable"><code>y</code></em>.  In addition, there is an optional parameter <em class="replaceable"><code>v</code></em> and
a keyword parameter <em class="replaceable"><code>k</code></em>.  This signature also indicates that the
method's parameter specializers are the classes <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>.
</p><p>The description of each method includes a description of the
behavior particular to that method.</p><p>An abbreviated syntax is used when referring to a method defined
elsewhere in the document.  This abbreviated syntax includes the name of
the generic function, the qualifiers, and the parameter specializers.  A
reference to the method with the signature shown above is written as:
<span class="method"><code class="literal"><code class="function">gf1</code> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</code></span>.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-package"></a>29.1.2. Package</h3></div></div></div><p>The package exporting the <a class="link" href="#mop-chap" title="Chapter 29. Meta-Object Protocol">Meta-Object Protocol</a> symbols is unspecified.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>The symbols specified by the <a class="link" href="#mop-chap" title="Chapter 29. Meta-Object Protocol">Meta-Object Protocol</a> are
  exported from the package <a class="link" href="#classes" title="4.2. Classes sec_4-3"><strong class="package"><span class="quote">“<span class="quote">CLOS</span>”</span></strong></a> and <a class="link" href="#re-export" title="11.1.3. Function EXT:RE-EXPORT"><code class="function">EXT:RE-EXPORT</code></a>ed from the package
  <a class="link" href="#ext-pac"><strong class="package"><span class="quote">“<span class="quote">EXT</span>”</span></strong></a>.</p></div><p>The package exporting the <a class="link" href="#mop-chap" title="Chapter 29. Meta-Object Protocol">Meta-Object Protocol</a> symbols is different in other
implementations: In <a class="ulink" href="http://sbcl.sourceforge.net/" target="_top"><span class="command"><strong>SBCL</strong></span></a> it is the package
 <strong class="package"><span class="quote">“<span class="quote">SB-MOP</span>”</span></strong>;
in <a class="ulink" href="http://openmcl.clozure.com/" target="_top"><span class="command"><strong>OpenMCL</strong></span></a> it is the package
 <strong class="package"><span class="quote">“<span class="quote">OPENMCL-MOP</span>”</span></strong>.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="mop-overview"></a>29.2. Overview</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-metaobjects">29.2.1. Metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-mo-classes">29.2.1.1. Classes</a></span></dt><dt><span class="section"><a href="#mop-mo-slot-defs">29.2.1.2. Slot Definitions</a></span></dt><dt><span class="section"><a href="#mop-mo-gen-funs">29.2.1.3. Generic Functions</a></span></dt><dt><span class="section"><a href="#mop-mo-methods">29.2.1.4. Methods</a></span></dt><dt><span class="section"><a href="#mop-mo-spec">29.2.1.5. Specializers</a></span></dt><dt><span class="section"><a href="#mop-mo-meth-combs">29.2.1.6. Method Combinations</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-mo-cl-inheritance">29.2.2. Inheritance Structure of Metaobject Classes</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-ov-impl-and-user-spec">29.2.2.1. Implementation and User Specialization</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-portable-restrictions">29.2.2.1.1. Restrictions on Portable Programs</a></span></dt><dt><span class="section"><a href="#mop-impl-restrictions">29.2.2.1.2. Restrictions on Implementations</a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="#mop-ui-macro">29.2.3. Processing of the User Interface Macros</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-compile-ui-macro">29.2.3.1. Compile-file Processing of the User Interface Macros</a></span></dt><dt><span class="section"><a href="#mop-ov-ui-others">29.2.3.2. Compile-file Processing of Specific User Interface Macros</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-ov-mo-init">29.2.4. Metaobject Initialization Protocol</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-metaobjects"></a>29.2.1. Metaobjects</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-mo-classes">29.2.1.1. Classes</a></span></dt><dt><span class="section"><a href="#mop-mo-slot-defs">29.2.1.2. Slot Definitions</a></span></dt><dt><span class="section"><a href="#mop-mo-gen-funs">29.2.1.3. Generic Functions</a></span></dt><dt><span class="section"><a href="#mop-mo-methods">29.2.1.4. Methods</a></span></dt><dt><span class="section"><a href="#mop-mo-spec">29.2.1.5. Specializers</a></span></dt><dt><span class="section"><a href="#mop-mo-meth-combs">29.2.1.6. Method Combinations</a></span></dt></dl></div><p>For each kind of program element there is a corresponding
 <strong class="first"><em class="firstterm">basic metaobject class
  <a id="mop-ba-mo-cl" class="indexterm"></a></em></strong>.
These are the classes: <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>, <a class="link" href="#mop-sd" title="29.4. Slot Definitions"><code class="classname">CLOS:SLOT-DEFINITION</code></a>,
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_generic-function.html" target="_top"><code class="classname">GENERIC-FUNCTION</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method-combination.html" target="_top"><code class="classname">METHOD-COMBINATION</code></a>.
A <strong class="first"><em class="firstterm">metaobject class<a id="mo-cl" class="indexterm"></a></em></strong>
is a subclass of exactly one of these classes.
The results are undefined if an attempt is made to define a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>
that is a subclass of more than one basic metaobject class.
A <strong class="first"><em class="firstterm">metaobject<a id="mop-mo" class="indexterm"></a></em></strong> is an instance of a metaobject class.</p><p>Each metaobject represents one program element.  Associated with
each metaobject is the information required to serve its role.  This
includes information that might be provided directly in a user interface
macro such as <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a>.  It also includes information
computed indirectly from other metaobjects such as that computed from
class inheritance or the full set of methods associated with a generic
function.</p><p>Much of the information associated with a metaobject is in the
form of connections to other metaobjects.  This interconnection means
that the role of a metaobject is always based on that of other
metaobjects.  As an introduction to this interconnected structure, this
section presents a partial enumeration of the kinds of information
associated with each kind of metaobject.  More detailed information is
presented later.</p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-mo-classes"></a>29.2.1.1. Classes</h4></div></div></div><p>A <strong class="first"><em class="firstterm">class metaobject
  <a id="mop-class-mo" class="indexterm"></a></em></strong>
determines the structure and the default behavior of its instances.
The following information is associated with <a class="link" href="#mop-class-mo">class metaobject</a>s:

</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The name, if there is one, is available as an object.
</li><li class="listitem">The direct subclasses, direct superclasses and class
  precedence list are available as lists of <a class="link" href="#mop-class-mo">class metaobject</a>s.</li><li class="listitem">The slots defined directly in the class are available
  as a list of <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s.  The slots which are accessible in instances of
  the class are available as a list of <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s.</li><li class="listitem">The methods which use the class as a specializer, and
  the generic functions associated with those methods are available as
  lists of method and <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>s respectively.</li><li class="listitem">The documentation is available as a
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</li></ul></div><p>See also <a class="xref" href="#mop-classes" title="29.3. Classes">Section 29.3, “Classes”</a></p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-mo-slot-defs"></a>29.2.1.2. Slot Definitions</h4></div></div></div><p>A <strong class="first"><em class="firstterm">slot definition metaobject
  <a id="mop-slot-def-mo" class="indexterm"></a></em></strong>
 contains information about the definition of a slot.
There are two kinds of <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><strong class="first"><em class="firstterm">direct<a id="mop-dsd-mo" class="indexterm"></a></em></strong> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a></span></dt><dd>Used to represent the direct definition of a slot in
  a class. This corresponds roughly to the slot specifiers found in
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> forms.</dd><dt><span class="term"><strong class="first"><em class="firstterm">effective<a id="mop-esd-mo" class="indexterm"></a></em></strong> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a></span></dt><dd>Used to represent information, including inherited
   information, about a slot which is accessible in instances of a
   particular class.</dd></dl></div><p>Associated with each <a class="link" href="#mop-class-mo">class metaobject</a> is a list of <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s representing the
slots defined directly in the class.
Also associated with each <a class="link" href="#mop-class-mo">class metaobject</a> is a list of <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s representing the
set of slots accessible in instances of that class.</p><p>The following information is associated with both direct and
effective slot definitions metaobjects:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The name, allocation, and type are available as forms
  that could appear in a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form.</li><li class="listitem">The initialization form, if there is one, is
  available as a form that could appear in a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form.  The
  initialization form together with its <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a> is available
  as a function of no arguments which, when called, returns the result
  of evaluating the initialization form in its <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a>. This
  is called the <strong class="first"><em class="firstterm">initfunction</em></strong> of the slot.
</li><li class="listitem">The slot filling initialization arguments are
  available as a list of symbols.</li><li class="listitem">The documentation is available as a
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</li></ul></div><p>Certain other information is only associated with <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s.
 This information applies only to the direct definition of the slot in
 the class (it is not inherited).
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The function names of those generic
  functions for which there are automatically generated reader and
  writer methods.  This information is available as lists of function
  names.  Any accessors specified in the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form are broken down
  into their equivalent readers and writers in the direct slot
  definition.</li></ul></div><p>Information, including inherited information, which applies to the
definition of a slot in a particular class in which it is accessible is
associated only with <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s.
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">For certain slots, the location of the
slot in instances of the class is available.
</li></ul></div><p>See also <a class="xref" href="#mop-sd" title="29.4. Slot Definitions">Section 29.4, “Slot Definitions”</a></p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-mo-gen-funs"></a>29.2.1.3. Generic Functions</h4></div></div></div><p>A <strong class="first"><em class="firstterm">generic function metaobject
  <a id="mop-gen-fun-mo" class="indexterm"></a></em></strong>
 contains information about a generic function over and above the
 information associated with each of the generic function's methods.
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The name is available as a function name.
</li><li class="listitem">The methods associated with the generic function are
  available as a list of <a class="link" href="#mop-method-mo">method metaobject</a>s.</li><li class="listitem">The default class for this generic function's <a class="link" href="#mop-method-mo">method metaobject</a>s
  is available as a <a class="link" href="#mop-class-mo">class metaobject</a>.</li><li class="listitem">The <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> is available as a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>.
</li><li class="listitem">The method combination is available as a <a class="link" href="#mop-meth-comp-mo">method combination metaobject</a>.
</li><li class="listitem">The argument precedence order is available as a
  permutation of those symbols from the <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> which name the
  required arguments of the generic function.</li><li class="listitem"><p class="simpara">The <span class="quote">“<span class="quote">declarations</span>”</span> are available as a
 list of <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_d.html#declaration_specifier">declaration specifier</a>s.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>There is a slight misnomer in the naming of functions and
 options in this document: Where the term <span class="quote">“<span class="quote">declaration</span>”</span> is
 used, actually a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_d.html#declaration_specifier">declaration specifier</a> is meant.
</p></div></li><li class="listitem">The documentation is available as a
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</li></ul></div><p>See also <a class="xref" href="#mop-gf" title="29.5. Generic Functions">Section 29.5, “Generic Functions”</a></p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-mo-methods"></a>29.2.1.4. Methods</h4></div></div></div><p>A <strong class="first"><em class="firstterm">method metaobject
  <a id="mop-method-mo" class="indexterm"></a></em></strong>
 contains information about a specific <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a>.
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The qualifiers are available as a
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of of non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> atoms.</li><li class="listitem">The <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> is available as a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>.
</li><li class="listitem">The specializers are available as a list of
  specializer metaobjects.</li><li class="listitem">The function is available as a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a>.  This
  function can be applied to arguments and a list of next methods using
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_apply.html" target="_top"><code class="function">APPLY</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_funcall.html" target="_top"><code class="function">FUNCALL</code></a>.</li><li class="listitem">When the method is associated with a generic
  function, that <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> is available.  A method can be associated with
  at most one generic function at a time.</li><li class="listitem">The documentation is available as a
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</li></ul></div><p>See also <a class="xref" href="#mop-meth" title="29.6. Methods">Section 29.6, “Methods”</a></p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-mo-spec"></a>29.2.1.5. Specializers</h4></div></div></div><p>A <strong class="first"><em class="firstterm">specializer metaobject
  <a id="spec-mo" class="indexterm"></a></em></strong>
 represents the specializers of a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a>.
 <a class="link" href="#mop-class-mo">class metaobject</a>s are themselves specializer metaobjects.  A special
 kind of specializer metaobject is used for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typspe_eql.html" target="_top"><code class="classname">EQL</code></a> specializers.</p><p>See also <a class="xref" href="#mop-specializers" title="29.8. Specializers">Section 29.8, “Specializers”</a></p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-mo-meth-combs"></a>29.2.1.6. Method Combinations</h4></div></div></div><p>A <strong class="first"><em class="firstterm">method combination metaobject
  <a id="mop-meth-comp-mo" class="indexterm"></a></em></strong>
 represents the information about the method combination being used by a
 generic function.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>This document does not specify the structure of <a class="link" href="#mop-meth-comp-mo">method combination metaobject</a>s.
</p></div><p>See also <a class="xref" href="#mop-meth-comb" title="29.9. Method Combinations">Section 29.9, “Method Combinations”</a></p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-mo-cl-inheritance"></a>29.2.2. Inheritance Structure of Metaobject Classes</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-ov-impl-and-user-spec">29.2.2.1. Implementation and User Specialization</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-portable-restrictions">29.2.2.1.1. Restrictions on Portable Programs</a></span></dt><dt><span class="section"><a href="#mop-impl-restrictions">29.2.2.1.2. Restrictions on Implementations</a></span></dt></dl></dd></dl></div><div class="figure"><a id="mop-mo-cl-inheritance-fig"></a><p class="title"><strong>Figure 29.1. Inheritance structure of metaobject classes</strong></p><div class="figure-contents"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="100%"><tr><td><img src="mop-classes-all.png" width="100%" alt="Inheritance structure of metaobject classes" /></td></tr></table></div></div></div><br class="figure-break" /><p>The inheritance structure of the specified metaobject classes is
 shown in <a class="xref" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes">Table 29.1, “Direct Superclass Relationships   Among The Specified Metaobject Classes”</a>. The class of every class
 shown is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a> except for the classes <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a>,
 which are instances of the class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_built-in-class.html" target="_top"><code class="classname">BUILT-IN-CLASS</code></a>, and the classes
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_generic-function.html" target="_top"><code class="classname">GENERIC-FUNCTION</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>, which are
 instances of the class <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>.
</p><div class="table"><a id="mop-inherit-struct"></a><p class="title"><strong>Table 29.1. Direct Superclass Relationships
  Among The Specified Metaobject Classes</strong></p><div class="table-contents"><table class="table" summary="Direct Superclass Relationships&#10;  Among The Specified Metaobject Classes" border="1"><colgroup><col /><col /><col /><col /></colgroup><thead><tr><th align="center">Metaobject Class</th><th align="center">Abstract</th><th align="center">Subclassable</th><th align="center">Direct Superclasses</th></tr></thead><tbody><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_standard-object.html" target="_top"><code class="classname">STANDARD-OBJECT</code></a></td><td align="center">no</td><td align="center">yes</td><td align="center">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</td></tr><tr><td align="center"><a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-OBJECT</code></a></td><td align="center">no</td><td align="center">yes</td><td align="center">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_standard-object.html" target="_top"><code class="classname">STANDARD-OBJECT</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a>)</td></tr><tr><td align="center"><a class="link" href="#mop-metaobjects" title="29.2.1. Metaobjects"><code class="classname">CLOS:METAOBJECT</code></a></td><td align="center">yes</td><td align="center">no</td><td align="center">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_standard-object.html" target="_top"><code class="classname">STANDARD-OBJECT</code></a>)</td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_generic-function.html" target="_top"><code class="classname">GENERIC-FUNCTION</code></a></td><td align="center">yes</td><td align="center">no</td><td align="center">(<a class="link" href="#mop-metaobjects" title="29.2.1. Metaobjects"><code class="classname">CLOS:METAOBJECT</code></a> <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-OBJECT</code></a>)</td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a></td><td align="center">no</td><td align="center">yes</td><td align="center">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_generic-function.html" target="_top"><code class="classname">GENERIC-FUNCTION</code></a>)</td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a></td><td align="center">yes</td><td align="center">no</td><td align="center">(<a class="link" href="#mop-metaobjects" title="29.2.1. Metaobjects"><code class="classname">CLOS:METAOBJECT</code></a>)</td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-method.html" target="_top"><code class="classname">STANDARD-METHOD</code></a></td><td align="center">no</td><td align="center">yes</td><td align="center">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a>)</td></tr><tr><td align="center"><a class="link" href="#mop-meth-init-mo" title="29.6.3.2. Initialization of method metaobjects"><code class="classname">CLOS:STANDARD-ACCESSOR-METHOD</code></a></td><td align="center">yes</td><td align="center">no</td><td align="center">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-method.html" target="_top"><code class="classname">STANDARD-METHOD</code></a>)</td></tr><tr><td align="center"><a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-READER-METHOD</code></a></td><td align="center">no</td><td align="center">yes</td><td align="center">(<a class="link" href="#mop-meth-init-mo" title="29.6.3.2. Initialization of method metaobjects"><code class="classname">CLOS:STANDARD-ACCESSOR-METHOD</code></a>)</td></tr><tr><td align="center"><a class="link" href="#writer-method-class" title="29.7.2.2. Generic Function CLOS:WRITER-METHOD-CLASS"><code class="classname">CLOS:STANDARD-WRITER-METHOD</code></a></td><td align="center">no</td><td align="center">yes</td><td align="center">(<a class="link" href="#mop-meth-init-mo" title="29.6.3.2. Initialization of method metaobjects"><code class="classname">CLOS:STANDARD-ACCESSOR-METHOD</code></a>)</td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method-combination.html" target="_top"><code class="classname">METHOD-COMBINATION</code></a></td><td align="center">yes</td><td align="center">no</td><td align="center">(<a class="link" href="#mop-metaobjects" title="29.2.1. Metaobjects"><code class="classname">CLOS:METAOBJECT</code></a>)</td></tr><tr><td align="center"><a class="link" href="#mop-sd" title="29.4. Slot Definitions"><code class="classname">CLOS:SLOT-DEFINITION</code></a></td><td align="center">yes</td><td align="center">no</td><td align="center">(<a class="link" href="#mop-metaobjects" title="29.2.1. Metaobjects"><code class="classname">CLOS:METAOBJECT</code></a>)</td></tr><tr><td align="center"><a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:DIRECT-SLOT-DEFINITION</code></a></td><td align="center">yes</td><td align="center">no</td><td align="center">(<a class="link" href="#mop-sd" title="29.4. Slot Definitions"><code class="classname">CLOS:SLOT-DEFINITION</code></a>)</td></tr><tr><td align="center"><a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:EFFECTIVE-SLOT-DEFINITION</code></a></td><td align="center">yes</td><td align="center">no</td><td align="center">(<a class="link" href="#mop-sd" title="29.4. Slot Definitions"><code class="classname">CLOS:SLOT-DEFINITION</code></a>)</td></tr><tr><td align="center"><a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-SLOT-DEFINITION</code></a></td><td align="center">yes</td><td align="center">no</td><td align="center">(<a class="link" href="#mop-sd" title="29.4. Slot Definitions"><code class="classname">CLOS:SLOT-DEFINITION</code></a>)</td></tr><tr><td align="center"><a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-DIRECT-SLOT-DEFINITION</code></a></td><td align="center">no</td><td align="center">yes</td><td align="center">(<a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-SLOT-DEFINITION</code></a> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:DIRECT-SLOT-DEFINITION</code></a>)</td></tr><tr><td align="center"><a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-EFFECTIVE-SLOT-DEFINITION</code></a></td><td align="center">no</td><td align="center">yes</td><td align="center">(<a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-SLOT-DEFINITION</code></a> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:EFFECTIVE-SLOT-DEFINITION</code></a>)</td></tr><tr><td align="center"><a class="link" href="#mop-mo-spec" title="29.2.1.5. Specializers"><code class="classname">CLOS:SPECIALIZER</code></a></td><td align="center">yes</td><td align="center">no</td><td align="center">(<a class="link" href="#mop-metaobjects" title="29.2.1. Metaobjects"><code class="classname">CLOS:METAOBJECT</code></a>)</td></tr><tr><td align="center"><a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:EQL-SPECIALIZER</code></a></td><td align="center">no</td><td align="center">no</td><td align="center">(<a class="link" href="#mop-mo-spec" title="29.2.1.5. Specializers"><code class="classname">CLOS:SPECIALIZER</code></a>)</td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a></td><td align="center">yes</td><td align="center">no</td><td align="center">(<a class="link" href="#mop-mo-spec" title="29.2.1.5. Specializers"><code class="classname">CLOS:SPECIALIZER</code></a>)</td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_built-in-class.html" target="_top"><code class="classname">BUILT-IN-CLASS</code></a></td><td align="center">no</td><td align="center">no</td><td align="center">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>)</td></tr><tr><td align="center"><a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a></td><td align="center">no</td><td align="center">no</td><td align="center">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>)</td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a></td><td align="center">no</td><td align="center">yes</td><td align="center">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>)</td></tr><tr><td align="center"><a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a></td><td align="center">no</td><td align="center">yes</td><td align="center">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>)</td></tr></tbody></table></div></div><p><br class="table-break" />
</p><p>Each class with a <span class="quote">“<span class="quote">yes</span>”</span> in the <span class="quote">“<span class="quote">Abstract</span>”</span>
column is an <span class="emphasis"><em>abstract class</em></span> and is not intended to
be instantiated.  The results are undefined if an attempt is made to
make an instance of one of these classes with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>.</p><p>Each class with a <span class="quote">“<span class="quote">yes</span>”</span> in
the <span class="quote">“<span class="quote">Subclassable</span>”</span> column can be used as direct superclass
for portable programs.  It is not meaningful to subclass a class that
has a <span class="quote">“<span class="quote">no</span>”</span> in this column.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>The class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a> is also subclassable: It
  is possible to create subclasses of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a> that do not inherit
  from <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-method.html" target="_top"><code class="classname">STANDARD-METHOD</code></a>.</p></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span> and some   other implementations</h3><p>The class <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-OBJECT</code></a>'s class
  precedence list contains <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a> before <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_standard-object.html" target="_top"><code class="classname">STANDARD-OBJECT</code></a>, not
  after <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_standard-object.html" target="_top"><code class="classname">STANDARD-OBJECT</code></a>.
  This is the most transparent way to realize the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] requirement
  (see the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] section <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_4-2-2.html">4.2.2
   <span class="quote">“<span class="quote">Type Relationships</span>”</span></a>)
  that <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_generic-function.html" target="_top"><code class="classname">GENERIC-FUNCTION</code></a>'s class precedence list contains
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a> before <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_standard-object.html" target="_top"><code class="classname">STANDARD-OBJECT</code></a>.</p></div><p>The classes <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>, <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-DIRECT-SLOT-DEFINITION</code></a>, <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-EFFECTIVE-SLOT-DEFINITION</code></a>,
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-method.html" target="_top"><code class="classname">STANDARD-METHOD</code></a>, <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-READER-METHOD</code></a>,
 <a class="link" href="#writer-method-class" title="29.7.2.2. Generic Function CLOS:WRITER-METHOD-CLASS"><code class="classname">CLOS:STANDARD-WRITER-METHOD</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a> are called
 <strong class="first"><em class="firstterm">standard metaobject
  <a id="std-mo" class="indexterm"></a></em></strong> classes.
 For each kind of metaobject, this is the class the user interface
 macros presented in the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> use by default.  These are also the
 classes on which user specializations are normally based.</p><p>The classes <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_built-in-class.html" target="_top"><code class="classname">BUILT-IN-CLASS</code></a>, <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a> and
 <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a> are special-purpose <a class="link" href="#mop-class-mo">class metaobject</a> classes.
 Built-in classes are instances of the class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_built-in-class.html" target="_top"><code class="classname">BUILT-IN-CLASS</code></a>.
 The class <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a> provides a special kind of
 instances described in <a class="xref" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances">Section 29.10.2, “Funcallable Instances”</a>.
 When the definition of a class references another class which has not
 yet been defined, an instance of <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a> is used as
 a stand-in until the class is actually defined.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="forward-referenced-class-clisp"></a>Implementation of class <code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code> in <span class="command"><strong>CLISP</strong></span></h3><p>The class <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a> is implemented in a way
  that fixes several flaws in the [<span class="citation"><a class="link" href="#amop" title="The Art of the Metaobject Protocol">AMOP</a></span>] specification.</p><p>It is not a subclass of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a> and <a class="link" href="#mop-mo-spec" title="29.2.1.5. Specializers"><code class="classname">CLOS:SPECIALIZER</code></a>, just a
  subclass of <a class="link" href="#mop-metaobjects" title="29.2.1. Metaobjects"><code class="classname">CLOS:METAOBJECT</code></a>, because forward references to classes are
  not classes and cannot be used as specializers of methods.  An [<span class="citation"><a class="link" href="#amop" title="The Art of the Metaobject Protocol">AMOP</a></span>]
  compatibility mode is provided, however, if you set the variable
  <strong class="first"><em class="firstterm"><code class="varname">CUSTOM:*FORWARD-REFERENCED-CLASS-MISDESIGN*</code>
   <a id="frc-bad" class="indexterm"></a></em></strong> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.
  In this mode, <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a> is formally a subclass of
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a> and <a class="link" href="#mop-mo-spec" title="29.2.1.5. Specializers"><code class="classname">CLOS:SPECIALIZER</code></a>, but the behaviour of
  <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a> instances is the same.</p><p>The [<span class="citation"><a class="link" href="#amop" title="The Art of the Metaobject Protocol">AMOP</a></span>] says that the first argument of <a class="link" href="#ensure-class-UC" title="29.3.6.3. Generic Function CLOS:ENSURE-CLASS-USING-CLASS"><code class="function">CLOS:ENSURE-CLASS-USING-CLASS</code></a> can
  be a <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a>.
  But from the description of <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a>, it is clear that it can
  only be a class returned by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_find-class.html" target="_top"><code class="function">FIND-CLASS</code></a>, and [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_find-class.html" target="_top"><code class="function">FIND-CLASS</code></a>
  cannot return a <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a>.</p><p>The [<span class="citation"><a class="link" href="#amop" title="The Art of the Metaobject Protocol">AMOP</a></span>] says that <a class="link" href="#ensure-class-UC" title="29.3.6.3. Generic Function CLOS:ENSURE-CLASS-USING-CLASS"><code class="function">CLOS:ENSURE-CLASS-USING-CLASS</code></a> creates a
  <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a> for not-yet-defined class symbols among the
  direct-superclasses list.  But this leads to many
  <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a> with the same name (since they cannot be
  stored and retrieved through <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_find-class.html" target="_top"><code class="function">FIND-CLASS</code></a>), and since <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_change-class.html" target="_top"><code class="function">CHANGE-CLASS</code></a>
  preserves the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a>-ness, after the class is defined, we have many
  class objects with the same name.</p><p>In the direct-superclasses list of non-finalized classes,
  <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a> instances can occur, denoting classes that
  have not yet been defined. When or after such a class gets defined,
  the <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a> instance is replaced with the real
  class.  <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> uses simple object replacement, not <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_change-class.html" target="_top"><code class="function">CHANGE-CLASS</code></a>, in
  this process.</p></div><p>The class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_standard-object.html" target="_top"><code class="classname">STANDARD-OBJECT</code></a> is the <span class="emphasis"><em>default direct
superclass</em></span> of the class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>.  When an instance
of the class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a> is created, and no direct superclasses are
explicitly specified, it defaults to the class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_standard-object.html" target="_top"><code class="classname">STANDARD-OBJECT</code></a>.  In
this way, any behavior associated with the class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_standard-object.html" target="_top"><code class="classname">STANDARD-OBJECT</code></a>
will be inherited, directly or indirectly, by all instances of the class
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>.  A subclass of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a> may have a different
class as its default direct superclass, but that class must be a
subclass of the class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_standard-object.html" target="_top"><code class="classname">STANDARD-OBJECT</code></a>.</p><p>The same is true for <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a> and
<a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-OBJECT</code></a>.</p><p>The class <a class="link" href="#mop-mo-spec" title="29.2.1.5. Specializers"><code class="classname">CLOS:SPECIALIZER</code></a> captures only the most basic behavior of
method specializers, and is not itself intended to be instantiated.  The
class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a> is a direct subclass of <a class="link" href="#mop-mo-spec" title="29.2.1.5. Specializers"><code class="classname">CLOS:SPECIALIZER</code></a> reflecting the
property that classes by themselves can be used as method specializers.
The class <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:EQL-SPECIALIZER</code></a> is used for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typspe_eql.html" target="_top"><code class="classname">EQL</code></a> specializers.</p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-ov-impl-and-user-spec"></a>29.2.2.1. Implementation and User Specialization</h4></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-portable-restrictions">29.2.2.1.1. Restrictions on Portable Programs</a></span></dt><dt><span class="section"><a href="#mop-impl-restrictions">29.2.2.1.2. Restrictions on Implementations</a></span></dt></dl></div><p>The purpose of the Metaobject Protocol is to provide users with a
powerful mechanism for extending and customizing the basic behavior of
the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a>.  As an object-oriented description of the basic <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a>
behavior, the Metaobject Protocol makes it possible to create these
extensions by defining specialized subclasses of existing metaobject
classes.</p><p>The Metaobject Protocol provides this capability without
interfering with the implementor's ability to develop high-performance
implementations.  This balance between user extensibility and
implementor freedom is mediated by placing explicit restrictions on
each.  Some of these restrictions are general---they apply to the entire
class graph and the applicability of all methods.  These are presented
in this section.</p><p>The following additional terminology is used to present these
restrictions:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Metaobjects are divided into three categories.  Those
  defined in this document are called <strong class="first"><em class="firstterm">specified
   <a id="mo-specified" class="indexterm"></a></em></strong>;
  those defined by an implementation but not mentioned in this document
  are called <strong class="first"><em class="firstterm">implementation-specific
   <a id="mo-impl" class="indexterm"></a></em></strong>;
  and those defined by a portable program are called <strong class="first"><em class="firstterm">portable
   <a id="mo-portable" class="indexterm"></a></em></strong>.
</li><li class="listitem">A class <em class="replaceable"><code>i</code></em> is <strong class="first"><em class="firstterm">interposed
   <a id="class-interposed" class="indexterm"></a>
  </em></strong> between two other classes <em class="replaceable"><code>k<sub>1</sub></code></em> and <em class="replaceable"><code>k<sub>2</sub></code></em> if and only
  if there is some path, following direct superclasses, from the class
  <em class="replaceable"><code>k<sub>1</sub></code></em> to the class <em class="replaceable"><code>k<sub>2</sub></code></em> which includes <em class="replaceable"><code>i</code></em>.</li><li class="listitem">A method is <strong class="first"><em class="firstterm">specialized
   <a id="method-specialized" class="indexterm"></a></em></strong>
  to a class if and only if that class is in the list of specializers
  associated with the method; and the method is in the list of methods
  associated with some generic function.</li><li class="listitem">In a given implementation, a specified method is said
  to have been <strong class="first"><em class="firstterm">promoted
   <a id="method-promoted" class="indexterm"></a></em></strong>
  if and only if the specializers of the method, <em class="replaceable"><code>x<sub>1</sub></code></em> ... <em class="replaceable"><code>x<sub>n</sub></code></em>, are
  defined in this specification as the classes <em class="replaceable"><code>k<sub>1</sub></code></em> ... <em class="replaceable"><code>k<sub>n</sub></code></em>, but in
  the implementation, one or more of the specializers
  <em class="replaceable"><code>x<sub>l</sub></code></em>, is a superclass of the class
  given in the specification <em class="replaceable"><code>k<sub>l</sub></code></em>.
</li><li class="listitem"><p>For a given generic function and set of arguments, a
  method <em class="replaceable"><code>k<sub>2</sub></code></em> <strong class="first"><em class="firstterm">extends
   <a id="method-extends" class="indexterm"></a></em></strong>
  a method <em class="replaceable"><code>k<sub>1</sub></code></em> if and only if:
  </p><div class="orderedlist"><ol class="orderedlist" type="i"><li class="listitem"><em class="replaceable"><code>k<sub>1</sub></code></em> and
     <em class="replaceable"><code>k<sub>2</sub></code></em> are both associated with the given generic function
   </li><li class="listitem"><em class="replaceable"><code>k<sub>1</sub></code></em> and <em class="replaceable"><code>k<sub>2</sub></code></em> are both applicable to the given
     arguments,</li><li class="listitem">the specializers and qualifiers of the methods are
     such that when the generic function is called, <em class="replaceable"><code>k<sub>2</sub></code></em> is executed
     before <em class="replaceable"><code>k<sub>1</sub></code></em>,</li><li class="listitem"><em class="replaceable"><code>k<sub>1</sub></code></em> will be executed if and only if
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locfun_call-next-method.html" target="_top"><code class="function">CALL-NEXT-METHOD</code></a> is invoked from within the body of <em class="replaceable"><code>k<sub>2</sub></code></em> and
   </li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locfun_call-next-method.html" target="_top"><code class="function">CALL-NEXT-METHOD</code></a> is invoked from within the body
     of <em class="replaceable"><code>k<sub>2</sub></code></em>, thereby causing <em class="replaceable"><code>k<sub>1</sub></code></em> to be executed.
</li></ol></div></li><li class="listitem"><p>For a given generic function and set of arguments, a
  method <em class="replaceable"><code>k<sub>2</sub></code></em> <strong class="first"><em class="firstterm">overrides
   <a id="method-overrides" class="indexterm"></a></em></strong>
  a method <em class="replaceable"><code>k<sub>1</sub></code></em> if and only if conditions <span class="emphasis"><em>i</em></span>
  through <span class="emphasis"><em>iv</em></span> above hold and,
  instead of <span class="emphasis"><em>v</em></span>,
  </p><div class="orderedlist"><ol class="orderedlist" start="6" type="i"><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locfun_call-next-method.html" target="_top"><code class="function">CALL-NEXT-METHOD</code></a> is not invoked from within the
     body of <em class="replaceable"><code>k<sub>2</sub></code></em>, thereby preventing <em class="replaceable"><code>k<sub>1</sub></code></em> from being executed.
</li></ol></div></li></ul></div><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="mop-portable-restrictions"></a>29.2.2.1.1. Restrictions on Portable Programs</h5></div></div></div><p>Portable programs are allowed to define subclasses of specified
classes, and are permitted to define methods on specified generic
functions, with the following restrictions: </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Portable programs must not redefine any specified
classes, generic functions, methods or method combinations.  Any method
defined by a portable program on a specified generic function must have
at least one specializer that is neither a specified class nor an
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typspe_eql.html" target="_top"><code class="classname">EQL</code></a> specializer whose associated value is an instance of a specified
class.</li><li class="listitem">Portable programs may define methods that extend
specified methods unless the description of the specified method
explicitly prohibits this.  Unless there is a specific statement to the
contrary, these extending methods must return whatever value was
returned by the call to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locfun_call-next-method.html" target="_top"><code class="function">CALL-NEXT-METHOD</code></a>.</li><li class="listitem"><p class="simpara">Portable programs may define methods that override
specified methods only when the description of the specified method
explicitly allows this.  Typically, when a method is allowed to be
overridden, a small number of related methods will need to be overridden
as well.</p><p class="simpara">An example of this is the specified methods on the generic
functions <a class="link" href="#add-dependent" title="29.11.1.2. Generic Function CLOS:ADD-DEPENDENT"><code class="function">CLOS:ADD-DEPENDENT</code></a>, <a class="link" href="#remove-dependent" title="29.11.1.3. Generic Function CLOS:REMOVE-DEPENDENT"><code class="function">CLOS:REMOVE-DEPENDENT</code></a> and <a class="link" href="#map-dependents" title="29.11.1.4. Generic Function CLOS:MAP-DEPENDENTS"><code class="function">CLOS:MAP-DEPENDENTS</code></a>.
Overriding a specified method on one of these generic functions requires
that the corresponding method on the other two generic functions be
overridden as well.</p></li><li class="listitem"><p class="simpara">Portable methods on specified generic functions
specialized to portable metaobject classes must be defined before any
instances of those classes (or any subclasses) are created, either
directly or indirectly by a call to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>.  Methods can be
defined after instances are created by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_all_ate-instance.html" target="_top"><code class="function">ALLOCATE-INSTANCE</code></a> however.
Portable metaobject classes cannot be redefined.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>The purpose of this last restriction is to permit
implementations to provide performance optimizations by analyzing, at
the time the first instance of a metaobject class is initialized, what
portable methods will be applicable to it.  This can make it possible to
optimize calls to those specified generic functions which would have no
applicable portable methods.</p></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="mop-mo-redef-clisp-warn"></a>Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>When a metaobject class is redefined,
  <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> issues a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_warning.html" target="_top"><code class="classname">WARNING</code></a> that the redefinition has no effect.
  To avoid this warning, place all metaobject class definitions in a
  separate file, compile it in a <span class="emphasis"><em>separate</em></span> session
  (because <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> is evaluated at <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#compile_time">compile time</a> too;
  see <a class="xref" href="#mop-ov-ui-others" title="29.2.3.2. Compile-file Processing of Specific User Interface Macros">Section 29.2.3.2, “Compile-file Processing of Specific User Interface Macros”</a>),
  and then <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_load.html" target="_top"><code class="function">LOAD</code></a> it only <span class="emphasis"><em>once</em></span> per session.
</p></div></li></ul></div><p>
</p><p>The results are undefined if any of
 these restrictions are violated.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>The specification technology used in this document needs
further development.  The concepts of object-oriented protocols and
subclass specialization are intuitively familiar to programmers of
object-oriented systems; the protocols presented here fit quite
naturally into this framework.  Nonetheless, in preparing this document,
we have found it difficult to give specification-quality descriptions of
the protocols in a way that makes it clear what extensions users can and
cannot write.  Object-oriented protocol specification is inherently
about specifying leeway, and this seems difficult using current
technology.</p></div></div><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="mop-impl-restrictions"></a>29.2.2.1.2. Restrictions on Implementations</h5></div></div></div><p>Implementations are allowed latitude to modify the structure of
specified classes and methods.  This includes: the interposition of
implementation-specific classes; the promotion of specified methods; and
the consolidation of two or more specified methods into a single method
specialized to interposed classes.</p><p>Any such modifications are permitted only so long as for any
portable class <em class="replaceable"><code>k</code></em> that is a subclass of one or more specified classes
<em class="replaceable"><code>k<sub>1</sub></code></em> ... <em class="replaceable"><code>k<sub>n</sub></code></em>, the following conditions are met:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">In the actual class precedence list of <em class="replaceable"><code>k</code></em>, the
  classes <em class="replaceable"><code>k<sub>1</sub></code></em> ... <em class="replaceable"><code>k<sub>n</sub></code></em> must appear in the same order as they would
  have if no implementation-specific modifications had been made.
</li><li class="listitem">The method applicability of any specified generic
  function must be the same in terms of behavior as it would have been
  had no implementation-specific changes been made.  This includes
  specified generic functions that have had portable methods added.  In
  this context, the expression <span class="quote">“<span class="quote">the same in terms of
  behavior</span>”</span> means that methods with the same behavior as those
  specified are applicable, and in the same order.</li><li class="listitem">No portable class <em class="replaceable"><code>k</code></em> may inherit, by virtue of
  being a direct or indirect subclass of a specified class, any slot for
  which the name is a symbol accessible in the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-2.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP-USER</span>”</span></strong></a> package or
  exported by any package defined in the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>].</li><li class="listitem">Implementations are free to define
  implementation-specific before- and after-methods on specified generic
  functions.  Implementations are also free to define
  implementation-specific around-methods with extending behavior.
</li></ul></div></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-ui-macro"></a>29.2.3. Processing of the User Interface Macros</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-compile-ui-macro">29.2.3.1. Compile-file Processing of the User Interface Macros</a></span></dt><dt><span class="section"><a href="#mop-ov-ui-others">29.2.3.2. Compile-file Processing of Specific User Interface Macros</a></span></dt></dl></div><p>A list in which the first element is one of the symbols
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-me_-combination.html" target="_top"><code class="function">DEFINE-METHOD-COMBINATION</code></a>,
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss181.html" target="_top"><code class="function">CLOS:GENERIC-FUNCTION</code></a>, <a class="link" href="#gen-flet"><code class="function">CLOS:GENERIC-FLET</code></a> or <a class="link" href="#gen-labels"><code class="function">CLOS:GENERIC-LABELS</code></a>, and which has proper
syntax for that macro is called a <strong class="first"><em class="firstterm">user interface macro
form</em></strong>.  This document provides an extended specification of
the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a> macros.</p><p>The user interface macros <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a>
can be used not only to define metaobjects that are instances of the
corresponding standard metaobject class, but also to define metaobjects
that are instances of appropriate portable metaobject classes.  To make
it possible for portable metaobject classes to properly process the
information appearing in the macro form, this document provides a
limited specification of the processing of these macro forms.</p><p>User interface macro forms can be <span class="emphasis"><em>evaluated</em></span>
or <span class="emphasis"><em>compiled</em></span> and later <span class="emphasis"><em>executed</em></span>.
The effect of evaluating or executing a user interface macro form is
specified in terms of calls to specified functions and generic functions
which provide the actual behavior of the macro.  The arguments received
by these functions and generic functions are derived in a specified way
from the macro form.</p><p>Converting a user interface macro form into the arguments to the
appropriate functions and generic functions has two major aspects: the
conversion of the macro argument syntax into a form more suitable for
later processing, and the processing of macro arguments which are forms
to be evaluated (including method bodies).</p><p>In the syntax of the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> macro, the <em class="replaceable"><code>initform</code></em>
and <em class="replaceable"><code>default-initarg-initial-value-form</code></em>
arguments are forms which will be evaluated one or more times after the
macro form is evaluated or executed.  Special processing must be done on
these arguments to ensure that the lexical scope of the forms is
captured properly.  This is done by building a function of zero
arguments which, when called, returns the result of evaluating the form
in the proper <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a>.</p><p>In the syntax of the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a> macro
the <em class="replaceable"><code>forms</code></em> argument is a list of forms that
comprise the body of the method definition.  This list of forms must be
processed specially to capture the lexical scope of the macro form.  In
addition, the lexical functions available only in the body of methods
must be introduced.  To allow this and any other special processing
(such as slot access optimization), a specializable protocol is used for
processing the body of methods.
This is discussed in <a class="xref" href="#mop-meth-init-defmethod-body" title="29.6.3.1.1. Processing Method Bodies">Section 29.6.3.1.1, “Processing Method Bodies”</a>.</p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-compile-ui-macro"></a>29.2.3.1. Compile-file Processing of the User Interface Macros</h4></div></div></div><p>It is a common practice for <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> compilers, while processing a file
or set of files, to maintain information about the definitions that have
been compiled so far.  Among other things, this makes it possible to
ensure that a global macro definition (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmacro.html" target="_top"><code class="function">DEFMACRO</code></a> form) which appears in
a file will affect uses of the macro later in that file.
This information about the state of the compilation is called the
<strong class="first"><em class="firstterm"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile-file.html" target="_top"><code class="function">COMPILE-FILE</code></a> environment</em></strong>.</p><p>When compiling files containing <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> definitions, it is useful
to maintain certain additional information in the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile-file.html" target="_top"><code class="function">COMPILE-FILE</code></a> environment.
This can make it possible to issue various kinds of warnings (e.g.,
<a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> congruence) and to do various performance optimizations that
would not otherwise be possible.</p><p>At this time, there is such significant variance in the way
existing <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> implementations handle <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile-file.html" target="_top"><code class="function">COMPILE-FILE</code></a> environments that it
would be premature to specify this mechanism.  Consequently, this
document specifies only the behavior of evaluating or executing user
interface macro forms. What functions and generic functions are called
during <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile-file.html" target="_top"><code class="function">COMPILE-FILE</code></a> processing of a user interface macro form is not
specified.  Implementations are free to define and document their own
behavior.  Users may need to check implementation-specific behavior
before attempting to compile certain portable programs.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-ov-ui-others"></a>29.2.3.2. Compile-file Processing of Specific User Interface Macros</h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a></span></dt><dd><p class="simpara"><a class="xref" href="#mop-cl-defclass" title="29.3.1. Macro DEFCLASS">Section 29.3.1, “Macro <code class="function">DEFCLASS</code>”</a></p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> evaluates <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> forms also at
     <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#compile_time">compile time</a>.</p></div></dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a></span></dt><dd><p class="simpara"><a class="xref" href="#mop-meth-init-defmethod" title="29.6.3.1. Macro DEFMETHOD">Section 29.6.3.1, “Macro <code class="function">DEFMETHOD</code>”</a></p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> does <span class="strong"><strong>not</strong></span> evaluate <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a>
     forms at <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#compile_time">compile time</a> except as necessary for signature checking.
 </p></div></dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a></span></dt><dd><p class="simpara"><a class="xref" href="#mop-gf-init-defgeneric" title="29.5.3.1. Macro DEFGENERIC">Section 29.5.3.1, “Macro <code class="function">DEFGENERIC</code>”</a></p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> does <span class="strong"><strong>not</strong></span> evaluate <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a>
     forms at <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#compile_time">compile time</a> except as necessary for signature checking.
</p></div></dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-ov-mo-init"></a>29.2.4. Metaobject Initialization Protocol</h3></div></div></div><p>Like other objects, metaobjects can be created by calling
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>.  The initialization arguments passed to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>
are used to initialize the metaobject in the usual way.  The set of
legal initialization arguments, and their interpretation, depends on the
kind of metaobject being created.  Implementations and portable programs
are free to extend the set of legal initialization arguments.  Detailed
information about the initialization of each kind of metaobject are
provided in the appropriate sections:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="xref" href="#mop-cl-init-mo" title="29.3.5.1. Initialization of class metaobjects">Section 29.3.5.1, “Initialization of class metaobjects”</a></li><li class="listitem"><a class="xref" href="#mop-cl-reinit-mo" title="29.3.5.2. Reinitialization of class metaobjects">Section 29.3.5.2, “Reinitialization of class metaobjects”</a></li><li class="listitem"><a class="xref" href="#mop-gf-init-mo" title="29.5.3.3. Initialization of generic function metaobjects">Section 29.5.3.3, “Initialization of generic function metaobjects”</a></li><li class="listitem"><a class="xref" href="#mop-cl-finalization" title="29.3.4. Class Finalization Protocol">Section 29.3.4, “Class Finalization Protocol”</a></li><li class="listitem"><a class="xref" href="#mop-sa-instance-struct" title="29.10.1. Instance Structure Protocol">Section 29.10.1, “Instance Structure Protocol”</a></li><li class="listitem"><a class="xref" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances">Section 29.10.2, “Funcallable Instances”</a></li><li class="listitem"><a class="xref" href="#mop-gf-invocation" title="29.5.3.2. Generic Function Invocation Protocol">Section 29.5.3.2, “Generic Function Invocation Protocol”</a></li><li class="listitem"><a class="xref" href="#mop-dep-maint" title="29.11. Dependent Maintenance">Section 29.11, “Dependent Maintenance”</a></li></ul></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="mop-classes"></a>29.3. Classes</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-cl-defclass">29.3.1. Macro <code class="function">DEFCLASS</code></a></span></dt><dt><span class="section"><a href="#mop-cl-Inheritance">29.3.2. Inheritance Structure of class metaobject Classes</a></span></dt><dt><span class="section"><a href="#mop-cl-readers">29.3.3. Introspection: Readers for class metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#class-name">29.3.3.1. Generic Function <code class="function">CLASS-NAME</code></a></span></dt><dt><span class="section"><a href="#class-direct-superclasses">29.3.3.2. Generic Function <code class="function">CLOS:CLASS-DIRECT-SUPERCLASSES</code></a></span></dt><dt><span class="section"><a href="#class-direct-slots">29.3.3.3. Generic Function <code class="function">CLOS:CLASS-DIRECT-SLOTS</code></a></span></dt><dt><span class="section"><a href="#class-direct-default-initargs">29.3.3.4. Generic Function <code class="function">CLOS:CLASS-DIRECT-DEFAULT-INITARGS</code></a></span></dt><dt><span class="section"><a href="#cpl">29.3.3.5. Generic Function <code class="function">CLOS:CLASS-PRECEDENCE-LIST</code></a></span></dt><dt><span class="section"><a href="#class-direct-subclasses">29.3.3.6. Generic Function <code class="function">CLOS:CLASS-DIRECT-SUBCLASSES</code></a></span></dt><dt><span class="section"><a href="#class-slots">29.3.3.7. Generic Function <code class="function">CLOS:CLASS-SLOTS</code></a></span></dt><dt><span class="section"><a href="#class-default-initargs">29.3.3.8. Generic Function <code class="function">CLOS:CLASS-DEFAULT-INITARGS</code></a></span></dt><dt><span class="section"><a href="#class-finalized-p">29.3.3.9. Generic Function <code class="function">CLOS:CLASS-FINALIZED-P</code></a></span></dt><dt><span class="section"><a href="#class-prototype">29.3.3.10. Generic Function <code class="function">CLOS:CLASS-PROTOTYPE</code></a></span></dt><dt><span class="section"><a href="#mop-cl-readers-methods">29.3.3.11. Methods</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-cl-finalization">29.3.4. Class Finalization Protocol</a></span></dt><dt><span class="section"><a href="#mop-cl-init">29.3.5. Class Initialization</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-cl-init-mo">29.3.5.1. Initialization of class metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#class-mo-init-methods">29.3.5.1.1. Methods</a></span></dt><dt><span class="section"><a href="#mop-cl-init-anon">29.3.5.1.2. Initialization of Anonymous Classes</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-cl-reinit-mo">29.3.5.2. Reinitialization of class metaobjects</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-cl-customize">29.3.6. Customization</a></span></dt><dd><dl><dt><span class="section"><a href="#setf-class-name">29.3.6.1. Generic Function <code class="code">(SETF CLASS-NAME)</code></a></span></dt><dt><span class="section"><a href="#ensure-class">29.3.6.2. Generic Function <code class="function">CLOS:ENSURE-CLASS</code></a></span></dt><dt><span class="section"><a href="#ensure-class-UC">29.3.6.3. Generic Function <code class="function">CLOS:ENSURE-CLASS-USING-CLASS</code></a></span></dt><dt><span class="section"><a href="#finalize-inheritance">29.3.6.4. Generic Function <code class="function">CLOS:FINALIZE-INHERITANCE</code></a></span></dt><dt><span class="section"><a href="#mop-make-instance">29.3.6.5. Generic Function <code class="function">MAKE-INSTANCE</code></a></span></dt><dt><span class="section"><a href="#alloc-instance">29.3.6.6. Generic Function <code class="function">ALLOCATE-INSTANCE</code></a></span></dt><dt><span class="section"><a href="#validate-superclass">29.3.6.7. Generic Function <code class="function">CLOS:VALIDATE-SUPERCLASS</code></a></span></dt><dt><span class="section"><a href="#compute-dsd-initargs">29.3.6.8. Generic Function <code class="function">CLOS:COMPUTE-DIRECT-SLOT-DEFINITION-INITARGS</code></a></span></dt><dt><span class="section"><a href="#dsd-class">29.3.6.9. Generic Function <code class="function">CLOS:DIRECT-SLOT-DEFINITION-CLASS</code></a></span></dt><dt><span class="section"><a href="#compute-cpl">29.3.6.10. Generic Function <code class="function">CLOS:COMPUTE-CLASS-PRECEDENCE-LIST</code></a></span></dt><dt><span class="section"><a href="#compute-slots">29.3.6.11. Generic Function <code class="function">CLOS:COMPUTE-SLOTS</code></a></span></dt><dt><span class="section"><a href="#compute-esd">29.3.6.12. Generic Function <code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION</code></a></span></dt><dt><span class="section"><a href="#compute-esd-initargs">29.3.6.13. Generic Function <code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION-INITARGS</code></a></span></dt><dt><span class="section"><a href="#esd-class">29.3.6.14. Generic Function <code class="function">CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS</code></a></span></dt><dt><span class="section"><a href="#compute-default-initargs">29.3.6.15. Generic Function <code class="function">CLOS:COMPUTE-DEFAULT-INITARGS</code></a></span></dt></dl></dd><dt><span class="section"><a href="#mop-cl-dep">29.3.7. Updating Dependencies</a></span></dt><dd><dl><dt><span class="section"><a href="#add-direct-subclass">29.3.7.1. Generic Function <code class="function">CLOS:ADD-DIRECT-SUBCLASS</code></a></span></dt><dt><span class="section"><a href="#remove-direct-subclass">29.3.7.2. Generic Function <code class="function">CLOS:REMOVE-DIRECT-SUBCLASS</code></a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-cl-defclass"></a>29.3.1. Macro <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a></h3></div></div></div><p>The evaluation or execution of a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form results in a call
to the <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a> function. The arguments received by <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a>
are derived from the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form in a defined way.  The exact
macro-expansion of the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form is not defined, only the
relationship between the arguments to the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> macro and the
arguments received by the <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a> function.  Examples of typical
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> forms and sample expansions are shown in the following two
 examples:
</p><div class="informalexample"><a id="mop-cl-defclass-ex-1"></a><p>A <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form with
  standard slot and class options and an expansion of it that would
  result in the proper call to <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a>.</p><pre class="programlisting">
(defclass plane (moving-object graphics-object)
  ((altitude :initform 0 :accessor plane-altitude)
   (speed))
  (:default-initargs :engine *jet*))

(ensure-class 'plane
  ':direct-superclasses '(moving-object graphics-object)
  ':direct-slots (list (list ':name 'altitude
                             ':initform '0
                             ':initfunction #'(lambda () 0)
                             ':readers '(plane-altitude)
                             ':writers '((setf plane-altitude)))
                       (list ':name 'speed))
  ':direct-default-initargs (list (list ':engine
                                        '*jet*
                                        #'(lambda () *jet*))))
</pre></div><p>
</p><div class="informalexample"><a id="mop-cl-defclass-ex-2"></a><p>A <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form
  with non-standard class and slot options, and an expansion of it which
  results in the proper call to <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a>.  Note that the order of
  the slot options has not affected the order of the properties in the
  <a class="link" href="#mop-canonicalized-slot-spec">canonicalized slot specification</a>, but has affected the order of the elements
  in the lists which are the values of those properties.</p><pre class="programlisting">
(defclass sst (plane)
  ((mach mag-step 2
         locator sst-mach
         locator mach-location
         :reader mach-speed
         :reader mach))
  (:metaclass faster-class)
  (another-option foo bar))

(ensure-class 'sst
  ':direct-superclasses '(plane)
  ':direct-slots (list (list ':name 'mach
                             ':readers '(mach-speed mach)
                             'mag-step '2
                             'locator '(sst-mach mach-location)))
  ':metaclass 'faster-class
  'another-option '(foo bar))
</pre></div><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The <em class="replaceable"><code>name</code></em> argument to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a>
   becomes the value of the first argument to <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a>.  This is
   the only positional argument accepted by <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a>; all other
   arguments are keyword arguments.</li><li class="listitem">The <code class="constant">:DIRECT-SUPERCLASSES</code> argument to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a>
  becomes the value of the <code class="constant">:DIRECT-SUPERCLASSES</code> keyword argument to
  <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a>.</li><li class="listitem"><p class="simpara">The <code class="constant">:DIRECT-SLOTS</code> argument to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> becomes
  the value of the <code class="constant">:DIRECT-SLOTS</code> keyword argument to <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a>.
  Special processing of this value is done to regularize the form of
  each slot specification and to properly capture the lexical scope of
  the initialization forms.  This is done by converting each slot
  specification to a property list called a
  <strong class="first"><em class="firstterm">canonicalized slot specification</em></strong>.
  The resulting list of <a class="link" href="#mop-canonicalized-slot-spec">canonicalized slot specification</a>s is the value
  of the <code class="constant">:DIRECT-SLOTS</code> keyword argument.</p><p><a id="mop-canonicalized-slot-spec"></a>Canonicalized slot
  specifications are later used as the keyword arguments to a generic
  function which will, in turn, pass them to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a> for use as
  a set of initialization arguments.  Each <a class="link" href="#mop-canonicalized-slot-spec">canonicalized slot specification</a> is
  formed from the corresponding slot specification as follows:
  </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; "><li class="listitem">The name of the slot is the value of the <code class="constant">:NAME</code>
     property.  This property appears in every
     <a class="link" href="#mop-canonicalized-slot-spec">canonicalized slot specification</a>.</li><li class="listitem">When the <code class="constant">:INITFORM</code> slot option is present in
     the slot specification, then both the <code class="constant">:INITFORM</code> and
     <code class="constant">:INITFUNCTION</code> properties are present in the <a class="link" href="#mop-canonicalized-slot-spec">canonicalized slot specification</a>.
     The value of the <code class="constant">:INITFORM</code> property is the
     initialization form.  The value of the <code class="constant">:INITFUNCTION</code> property is
     a function of zero arguments which, when called, returns the result
     of evaluating the initialization form in its proper <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a>.
   </li><li class="listitem">If the <code class="constant">:INITFORM</code> slot option is not present in
     the slot specification, then either the <code class="constant">:INITFUNCTION</code> property
     will not appear, or its value will be false.  In such cases, the
     value of the <code class="constant">:INITFORM</code> property, or whether it appears, is
     unspecified.</li><li class="listitem">The value of the <code class="constant">:INITARGS</code> property is a list
     of the values of each <code class="constant">:INITARG</code> slot option.  If there are no
     <code class="constant">:INITARG</code> slot options, then either the <code class="constant">:INITARGS</code> property
     will not appear or its value will be the empty list.
   </li><li class="listitem">The value of the <code class="constant">:READERS</code> property is a list of
     the values of each <code class="constant">:READER</code> and <code class="constant">:ACCESSOR</code> slot option.  If
     there are no <code class="constant">:READER</code> or <code class="constant">:ACCESSOR</code> slot options, then either
     the <code class="constant">:READERS</code> property will not appear or its value will be the
     empty list.</li><li class="listitem">The value of the <code class="constant">:WRITERS</code> property is a list of
     the values specified by each <code class="constant">:WRITER</code> and <code class="constant">:ACCESSOR</code> slot
     option.  The value specified by a <code class="constant">:WRITER</code> slot option is just
     the value of the slot option.  The value specified by an
     <code class="constant">:ACCESSOR</code> slot option is a two element list: the first element
     is the symbol <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>, the second element is the value of the slot
     option.  If there are no <code class="constant">:WRITER</code> or <code class="constant">:ACCESSOR</code> slot options,
     then either the <code class="constant">:WRITERS</code> property will not appear or its value
     will be the empty list.</li><li class="listitem">The value of the <code class="constant">:DOCUMENTATION</code> property is the
     value of the <code class="constant">:DOCUMENTATION</code> slot option.  If there is no
     <code class="constant">:DOCUMENTATION</code> slot option, then either the <code class="constant">:DOCUMENTATION</code>
     property will not appear or its value will be false.
   </li><li class="listitem">All other slot options appear as the values of
     properties with the same name as the slot option.  Note that this
     includes not only the remaining standard slot options
     (<code class="constant">:ALLOCATION</code> and <code class="constant">:TYPE</code>), but also any other options and
     values appearing in the slot specification.  If one of these slot
     options appears more than once, the value of the property will be a
     list of the specified values.</li><li class="listitem">An implementation is free to add additional
     properties to the <a class="link" href="#mop-canonicalized-slot-spec">canonicalized slot specification</a> provided these
     are not symbols accessible in the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-2.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP-USER</span>”</span></strong></a> package, or exported by
     any package defined in the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>].</li></ul></div></li><li class="listitem"><p class="simpara">The <code class="constant">:DEFAULT-INITARGS</code> class
  option, if it is present in the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form, becomes the value of
  the <code class="constant">:DIRECT-DEFAULT-INITARGS</code> keyword argument to <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a>.
  Special processing of this value is done to properly capture the
  lexical scope of the default value forms.  This is done by converting
  each default initarg in the class option into a
  <strong class="first"><em class="firstterm">canonicalized default initialization argument</em></strong>.
  The resulting list of <a class="link" href="#mop-canonicalized-default-initarg">canonicalized default initialization argument</a>s is the value of
  the <code class="constant">:DIRECT-DEFAULT-INITARGS</code> keyword argument to <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a>.
 </p><p class="simpara"><a id="mop-canonicalized-default-initarg"></a>A canonicalized default
  initarg is a list of three elements.  The first element is the name;
  the second is the actual form itself; and the third is a function of
  zero arguments which, when called, returns the result of evaluating
  the default value form in its proper <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a>.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>If a <code class="constant">:DEFAULT-INITARGS</code>
    class option is not present in the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form,
    <code class="constant">:DIRECT-DEFAULT-INITARGS</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> is passed to <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a>.</p><p>This is needed to
 fulfill the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] requirement (see <a class="xref" href="#redef-class" title="4.6. Redefining Classes sec_4-3-6">Section 4.6, “Redefining Classes   sec_4-3-6”</a>) that
 the resulting <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a> object reflects the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form.</p></div></li><li class="listitem"><p class="simpara">The <code class="constant">:METACLASS</code> class
  option, if it is present in the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form, becomes the value of
  the <code class="constant">:METACLASS</code> keyword argument to <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a>.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>If a <code class="constant">:METACLASS</code>
   class option is not present in the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form,
   <code class="constant">:METACLASS</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a> is passed to <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a>.</p><p>This is needed to
 fulfill the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] requirement (see <a class="xref" href="#redef-class" title="4.6. Redefining Classes sec_4-3-6">Section 4.6, “Redefining Classes   sec_4-3-6”</a>) that
 the resulting <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a> object reflects the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form.</p></div></li><li class="listitem"><p class="simpara">The <code class="constant">:DOCUMENTATION</code> class
  option, if it is present in the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form, becomes the value of
  the <code class="constant">:DOCUMENTATION</code> keyword argument to <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a>.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>If a <code class="constant">:DOCUMENTATION</code>
    class option is not present in the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form,
    <code class="constant">:DIRECT-DEFAULT-INITARGS</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> is passed to <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a>.</p><p>This is needed to
 fulfill the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] requirement (see <a class="xref" href="#redef-class" title="4.6. Redefining Classes sec_4-3-6">Section 4.6, “Redefining Classes   sec_4-3-6”</a>) that
 the resulting <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a> object reflects the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form.</p></div></li><li class="listitem"><p class="simpara">Any other class options become the value of keyword
  arguments with the same name.  The value of the keyword argument is
  the tail of the class option.  An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if any class
  option appears more than once in the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>The default initargs of the
    <code class="constant">:METACLASS</code> are added at the end of the list
    of arguments to pass to <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a>.</p><p>This is needed to
 fulfill the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] requirement (see <a class="xref" href="#redef-class" title="4.6. Redefining Classes sec_4-3-6">Section 4.6, “Redefining Classes   sec_4-3-6”</a>) that
 the resulting <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a> object reflects the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form.</p></div></li></ul></div><p>In the call to <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a>, every element of its arguments
appears in the same left-to-right order as the corresponding element of
the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form, except that the order of the properties of
<a class="link" href="#mop-canonicalized-slot-spec">canonicalized slot specification</a>s is unspecified.  The values of
properties in <a class="link" href="#mop-canonicalized-slot-spec">canonicalized slot specification</a>s do follow this ordering
requirement.  Other ordering relationships in the keyword arguments to
<a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a> are unspecified.</p><p>The result of the call to <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a> is returned as the result
of evaluating or executing the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> form.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-cl-Inheritance"></a>29.3.2. Inheritance Structure of <a class="link" href="#mop-class-mo">class metaobject</a> Classes</h3></div></div></div><div class="figure"><a id="mop-cl-Inheritance-fig"></a><p class="title"><strong>Figure 29.2. Inheritance structure of <a class="link" href="#mop-class-mo">class metaobject</a> classes</strong></p><div class="figure-contents"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="100%"><tr><td><img src="mop-classes-class.png" width="100%" alt="Inheritance structure of class metaobject classes" /></td></tr></table></div></div></div><br class="figure-break" /></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-cl-readers"></a>29.3.3. Introspection: Readers for <a class="link" href="#mop-class-mo">class metaobject</a>s</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#class-name">29.3.3.1. Generic Function <code class="function">CLASS-NAME</code></a></span></dt><dt><span class="section"><a href="#class-direct-superclasses">29.3.3.2. Generic Function <code class="function">CLOS:CLASS-DIRECT-SUPERCLASSES</code></a></span></dt><dt><span class="section"><a href="#class-direct-slots">29.3.3.3. Generic Function <code class="function">CLOS:CLASS-DIRECT-SLOTS</code></a></span></dt><dt><span class="section"><a href="#class-direct-default-initargs">29.3.3.4. Generic Function <code class="function">CLOS:CLASS-DIRECT-DEFAULT-INITARGS</code></a></span></dt><dt><span class="section"><a href="#cpl">29.3.3.5. Generic Function <code class="function">CLOS:CLASS-PRECEDENCE-LIST</code></a></span></dt><dt><span class="section"><a href="#class-direct-subclasses">29.3.3.6. Generic Function <code class="function">CLOS:CLASS-DIRECT-SUBCLASSES</code></a></span></dt><dt><span class="section"><a href="#class-slots">29.3.3.7. Generic Function <code class="function">CLOS:CLASS-SLOTS</code></a></span></dt><dt><span class="section"><a href="#class-default-initargs">29.3.3.8. Generic Function <code class="function">CLOS:CLASS-DEFAULT-INITARGS</code></a></span></dt><dt><span class="section"><a href="#class-finalized-p">29.3.3.9. Generic Function <code class="function">CLOS:CLASS-FINALIZED-P</code></a></span></dt><dt><span class="section"><a href="#class-prototype">29.3.3.10. Generic Function <code class="function">CLOS:CLASS-PROTOTYPE</code></a></span></dt><dt><span class="section"><a href="#mop-cl-readers-methods">29.3.3.11. Methods</a></span></dt></dl></div><p>In this and the following sections, the <span class="quote">“<span class="quote">reader</span>”</span>
generic functions which simply return information associated with a
particular kind of metaobject are presented together.  General
information is presented first, followed by a description of the purpose
of each, and ending with the specified methods for these generic
functions.</p><p>The reader generic functions which simply return information
associated with <a class="link" href="#mop-class-mo">class metaobject</a>s are presented together in this section.</p><p>Each of the reader generic functions for <a class="link" href="#mop-class-mo">class metaobject</a>s has the same
syntax, accepting one required argument called <em class="replaceable"><code>class</code></em>, which must be
a <a class="link" href="#mop-class-mo">class metaobject</a>; otherwise, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.  An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is also <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if
the <a class="link" href="#mop-class-mo">class metaobject</a> has not been initialized.</p><p>These
  generic functions can be called by the user or the implementation.</p><p>For any of these generic functions which returns a list, such lists
  will not be mutated by the implementation.  The results are undefined if a
  portable program allows such a list to be mutated.</p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="class-name"></a>29.3.3.1. Generic Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_class-name.html" target="_top"><code class="function">CLASS-NAME</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_class-name.html" target="_top"><code class="function">CLASS-NAME</code></a> <em class="replaceable"><code>class</code></em>)</code></h5></div></div></div><p>Returns the name of <em class="replaceable"><code>class</code></em>.  This value can be any Lisp object,
but is usually a symbol, or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if the class has no name.  This is the
defaulted value of the <code class="constant">:NAME</code> initialization argument that was
associated with the class during initialization or reinitialization.
(Also see <a class="link" href="#setf-class-name" title="29.3.6.1. Generic Function (SETF CLASS-NAME)"><code class="code">(SETF CLASS-NAME)</code></a>.)
</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="class-direct-superclasses"></a>29.3.3.2. Generic Function <a class="link" href="#class-direct-superclasses" title="29.3.3.2. Generic Function CLOS:CLASS-DIRECT-SUPERCLASSES"><code class="function">CLOS:CLASS-DIRECT-SUPERCLASSES</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#class-direct-superclasses" title="29.3.3.2. Generic Function CLOS:CLASS-DIRECT-SUPERCLASSES"><code class="function">CLOS:CLASS-DIRECT-SUPERCLASSES</code></a> <em class="replaceable"><code>class</code></em>)</code></h5></div></div></div><p>Returns a list of the direct superclasses of <em class="replaceable"><code>class</code></em>.  The
elements of this list are <a class="link" href="#mop-class-mo">class metaobject</a>s.  The empty list is returned if
<em class="replaceable"><code>class</code></em> has no direct superclasses.  This is the defaulted value of
the <code class="constant">:DIRECT-SUPERCLASSES</code> initialization argument that was associated
with the class during initialization or reinitialization.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>For a class that has not yet been finalized,
 the returned list may contain <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a> instances as
 placeholder for classes that were not yet defined when finalization of
 the class was last attempted.</p></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="class-direct-slots"></a>29.3.3.3. Generic Function <a class="link" href="#class-direct-slots" title="29.3.3.3. Generic Function CLOS:CLASS-DIRECT-SLOTS"><code class="function">CLOS:CLASS-DIRECT-SLOTS</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#class-direct-slots" title="29.3.3.3. Generic Function CLOS:CLASS-DIRECT-SLOTS"><code class="function">CLOS:CLASS-DIRECT-SLOTS</code></a> <em class="replaceable"><code>class</code></em>)</code></h5></div></div></div><p>Returns a set of the direct slots of <em class="replaceable"><code>class</code></em>.  The elements of
this set are <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s.  If the class has no direct slots, the empty set
is returned.  This is the defaulted value of the <code class="constant">:DIRECT-SLOTS</code>
initialization argument that was associated with the class during
initialization and reinitialization.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="class-direct-default-initargs"></a>29.3.3.4. Generic Function <a class="link" href="#class-direct-default-initargs" title="29.3.3.4. Generic Function CLOS:CLASS-DIRECT-DEFAULT-INITARGS"><code class="function">CLOS:CLASS-DIRECT-DEFAULT-INITARGS</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#class-direct-default-initargs" title="29.3.3.4. Generic Function CLOS:CLASS-DIRECT-DEFAULT-INITARGS"><code class="function">CLOS:CLASS-DIRECT-DEFAULT-INITARGS</code></a> <em class="replaceable"><code>class</code></em>)</code></h5></div></div></div><p>Returns a list of the direct default initialization arguments for
<em class="replaceable"><code>class</code></em>.  Each element of this list is a <a class="link" href="#mop-canonicalized-default-initarg">canonicalized default initialization argument</a>.
The empty list is returned if <em class="replaceable"><code>class</code></em> has no
direct default initialization arguments.  This is the defaulted value of
the <code class="constant">:DIRECT-DEFAULT-INITARGS</code> initialization argument that was
associated with the class during initialization or reinitialization.
</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="cpl"></a>29.3.3.5. Generic Function <a class="link" href="#cpl" title="29.3.3.5. Generic Function CLOS:CLASS-PRECEDENCE-LIST"><code class="function">CLOS:CLASS-PRECEDENCE-LIST</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#cpl" title="29.3.3.5. Generic Function CLOS:CLASS-PRECEDENCE-LIST"><code class="function">CLOS:CLASS-PRECEDENCE-LIST</code></a> <em class="replaceable"><code>class</code></em>)</code></h5></div></div></div><p>Returns the class precedence list of <em class="replaceable"><code>class</code></em>.
 The elements of this list are <a class="link" href="#mop-class-mo">class metaobject</a>s.</p><p>During class finalization <a class="link" href="#finalize-inheritance" title="29.3.6.4. Generic Function CLOS:FINALIZE-INHERITANCE"><code class="function">CLOS:FINALIZE-INHERITANCE</code></a> calls
<a class="link" href="#compute-cpl" title="29.3.6.10. Generic Function CLOS:COMPUTE-CLASS-PRECEDENCE-LIST"><code class="function">CLOS:COMPUTE-CLASS-PRECEDENCE-LIST</code></a> to compute the class precedence list of the class.  That
value is associated with the <a class="link" href="#mop-class-mo">class metaobject</a> and is returned by <a class="link" href="#cpl" title="29.3.3.5. Generic Function CLOS:CLASS-PRECEDENCE-LIST"><code class="function">CLOS:CLASS-PRECEDENCE-LIST</code></a>.</p><p>This generic function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> if <em class="replaceable"><code>class</code></em> has not been finalized.
</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="class-direct-subclasses"></a>29.3.3.6. Generic Function <a class="link" href="#class-direct-subclasses" title="29.3.3.6. Generic Function CLOS:CLASS-DIRECT-SUBCLASSES"><code class="function">CLOS:CLASS-DIRECT-SUBCLASSES</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#class-direct-subclasses" title="29.3.3.6. Generic Function CLOS:CLASS-DIRECT-SUBCLASSES"><code class="function">CLOS:CLASS-DIRECT-SUBCLASSES</code></a> <em class="replaceable"><code>class</code></em>)</code></h5></div></div></div><p>Returns a set of the direct subclasses of <em class="replaceable"><code>class</code></em>. The elements
of this set are <a class="link" href="#mop-class-mo">class metaobject</a>s that all mention this class among their direct
superclasses.  The empty set is returned if <em class="replaceable"><code>class</code></em> has no direct
subclasses.  This value is maintained by the generic functions
<a class="link" href="#add-direct-subclass" title="29.3.7.1. Generic Function CLOS:ADD-DIRECT-SUBCLASS"><code class="function">CLOS:ADD-DIRECT-SUBCLASS</code></a> and <a class="link" href="#remove-direct-subclass" title="29.3.7.2. Generic Function CLOS:REMOVE-DIRECT-SUBCLASS"><code class="function">CLOS:REMOVE-DIRECT-SUBCLASS</code></a>.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>The set of direct subclasses of a class is
 internally managed as a <a class="link" href="#weak-list" title="31.7.2. Weak Lists"><code class="classname">EXT:WEAK-LIST</code></a>. Therefore the existence of
 the <a class="link" href="#class-direct-subclasses" title="29.3.3.6. Generic Function CLOS:CLASS-DIRECT-SUBCLASSES"><code class="function">CLOS:CLASS-DIRECT-SUBCLASSES</code></a> function does not prevent otherwise
 unreferenced classes from being <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed.</p></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="class-slots"></a>29.3.3.7. Generic Function <a class="link" href="#class-slots" title="29.3.3.7. Generic Function CLOS:CLASS-SLOTS"><code class="function">CLOS:CLASS-SLOTS</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#class-slots" title="29.3.3.7. Generic Function CLOS:CLASS-SLOTS"><code class="function">CLOS:CLASS-SLOTS</code></a> <em class="replaceable"><code>class</code></em>)</code></h5></div></div></div><p>Returns a possibly empty set of the slots accessible in instances
of <em class="replaceable"><code>class</code></em>.  The elements of this set are <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s.</p><p>During class finalization <a class="link" href="#finalize-inheritance" title="29.3.6.4. Generic Function CLOS:FINALIZE-INHERITANCE"><code class="function">CLOS:FINALIZE-INHERITANCE</code></a> calls
<a class="link" href="#compute-slots" title="29.3.6.11. Generic Function CLOS:COMPUTE-SLOTS"><code class="function">CLOS:COMPUTE-SLOTS</code></a> to compute the slots of the class.  That value is
associated with the <a class="link" href="#mop-class-mo">class metaobject</a> and is returned by <a class="link" href="#class-slots" title="29.3.3.7. Generic Function CLOS:CLASS-SLOTS"><code class="function">CLOS:CLASS-SLOTS</code></a>.</p><p>This generic function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> if <em class="replaceable"><code>class</code></em> has not been finalized.
</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="class-default-initargs"></a>29.3.3.8. Generic Function <a class="link" href="#class-default-initargs" title="29.3.3.8. Generic Function CLOS:CLASS-DEFAULT-INITARGS"><code class="function">CLOS:CLASS-DEFAULT-INITARGS</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#class-default-initargs" title="29.3.3.8. Generic Function CLOS:CLASS-DEFAULT-INITARGS"><code class="function">CLOS:CLASS-DEFAULT-INITARGS</code></a> <em class="replaceable"><code>class</code></em>)</code></h5></div></div></div><p>Returns a list of the default initialization arguments for <em class="replaceable"><code>class</code></em>.
 Each element of this list is a <a class="link" href="#mop-canonicalized-default-initarg">canonicalized default initialization argument</a>.
 The empty list is returned if <em class="replaceable"><code>class</code></em> has no
 default initialization arguments.</p><p>During finalization <a class="link" href="#finalize-inheritance" title="29.3.6.4. Generic Function CLOS:FINALIZE-INHERITANCE"><code class="function">CLOS:FINALIZE-INHERITANCE</code></a> calls
<a class="link" href="#compute-default-initargs" title="29.3.6.15. Generic Function CLOS:COMPUTE-DEFAULT-INITARGS"><code class="function">CLOS:COMPUTE-DEFAULT-INITARGS</code></a> to compute the default initialization
arguments for the class.  That value is associated with the <a class="link" href="#mop-class-mo">class metaobject</a> and
is returned by <a class="link" href="#class-default-initargs" title="29.3.3.8. Generic Function CLOS:CLASS-DEFAULT-INITARGS"><code class="function">CLOS:CLASS-DEFAULT-INITARGS</code></a>.</p><p>This generic function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> if <em class="replaceable"><code>class</code></em> has not been
finalized.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="class-finalized-p"></a>29.3.3.9. Generic Function <a class="link" href="#class-finalized-p" title="29.3.3.9. Generic Function CLOS:CLASS-FINALIZED-P"><code class="function">CLOS:CLASS-FINALIZED-P</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#class-finalized-p" title="29.3.3.9. Generic Function CLOS:CLASS-FINALIZED-P"><code class="function">CLOS:CLASS-FINALIZED-P</code></a> <em class="replaceable"><code>class</code></em>)</code></h5></div></div></div><p>Returns true if <em class="replaceable"><code>class</code></em> has been finalized.  Returns false
otherwise.  Also returns false if the <em class="replaceable"><code>class</code></em> has not been initialized.
</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="class-prototype"></a>29.3.3.10. Generic Function <a class="link" href="#class-prototype" title="29.3.3.10. Generic Function CLOS:CLASS-PROTOTYPE"><code class="function">CLOS:CLASS-PROTOTYPE</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#class-prototype" title="29.3.3.10. Generic Function CLOS:CLASS-PROTOTYPE"><code class="function">CLOS:CLASS-PROTOTYPE</code></a> <em class="replaceable"><code>class</code></em>)</code></h5></div></div></div><p>Returns a prototype instance of <em class="replaceable"><code>class</code></em>.  Whether the instance
is initialized is not specified.  The results are undefined if a
portable program modifies the binding of any slot of a prototype instance.
</p><p>This generic function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> if <em class="replaceable"><code>class</code></em> has not been finalized.
</p><div class="informalexample"><a id="class-prototype-ex"></a><p>This allows non-<a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#cons">cons</a>ing[3]
  access to slots with allocation <code class="constant">:CLASS</code>:</p><pre class="programlisting">
(defclass counter ()
  ((count :allocation :class :initform 0 :reader how-many)))
(defmethod initialize-instance :after ((obj counter) &amp;rest args)
  (incf (slot-value obj 'count)))
(defclass counted-object (counter) ((name :initarg :name)))
 </pre><p>
 Now one can find out how many <code class="classname">COUNTED-OBJECT</code>s
 have been created by using
  <code class="code">(HOW-MANY (<a class="link" href="#class-prototype" title="29.3.3.10. Generic Function CLOS:CLASS-PROTOTYPE"><code class="function">CLOS:CLASS-PROTOTYPE</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_find-class.html" target="_top"><code class="function">FIND-CLASS</code></a> 'COUNTER)))</code>:
  </p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a> 'counted-object :name 'foo)
⇒ <code class="computeroutput">#&lt;COUNTED-OBJECT #x203028C9&gt;</code>
(HOW-MANY (<a class="link" href="#class-prototype" title="29.3.3.10. Generic Function CLOS:CLASS-PROTOTYPE"><code class="function">CLOS:CLASS-PROTOTYPE</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_find-class.html" target="_top"><code class="function">FIND-CLASS</code></a> 'counter)))
⇒ <code class="computeroutput">1</code>
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a> 'counted-object :name 'bar)
⇒ <code class="computeroutput">#&lt;COUNTED-OBJECT #x20306CB1&gt;</code>
(HOW-MANY (<a class="link" href="#class-prototype" title="29.3.3.10. Generic Function CLOS:CLASS-PROTOTYPE"><code class="function">CLOS:CLASS-PROTOTYPE</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_find-class.html" target="_top"><code class="function">FIND-CLASS</code></a> 'counter)))
⇒ <code class="computeroutput">2</code>
</pre></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-cl-readers-methods"></a>29.3.3.11. Methods</h4></div></div></div><p>The specified methods for the <a class="link" href="#mop-class-mo">class metaobject</a> reader generic
functions are presented below.</p><p>Each entry in the table indicates a method on one of the reader
 generic functions, specialized to a specified class.
 The number in each entry is a reference to the full description of the method.
 The full descriptions appear after the table.
</p><div class="informaltable"><a id="mop-cl-readers-methods-tab"></a><table class="informaltable" border="1"><colgroup><col /><col /><col /><col /></colgroup><thead><tr><th align="center">Generic Function</th><th align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>, <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a></th><th align="center"><a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a></th><th align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_built-in-class.html" target="_top"><code class="classname">BUILT-IN-CLASS</code></a></th></tr></thead><tbody><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_class-name.html" target="_top"><code class="function">CLASS-NAME</code></a></td><td align="center"><a class="xref" href="#CRM-1">1</a></td><td align="center"><a class="xref" href="#CRM-1">1</a></td><td align="center"><a class="xref" href="#CRM-8">8</a></td></tr><tr><td align="center"><a class="link" href="#class-direct-superclasses" title="29.3.3.2. Generic Function CLOS:CLASS-DIRECT-SUPERCLASSES"><code class="function">CLOS:CLASS-DIRECT-SUPERCLASSES</code></a></td><td align="center"><a class="xref" href="#CRM-1">1</a></td><td align="center"><a class="xref" href="#CRM-4">4</a></td><td align="center"><a class="xref" href="#CRM-7">7</a></td></tr><tr><td align="center"><a class="link" href="#class-direct-slots" title="29.3.3.3. Generic Function CLOS:CLASS-DIRECT-SLOTS"><code class="function">CLOS:CLASS-DIRECT-SLOTS</code></a></td><td align="center"><a class="xref" href="#CRM-1">1</a></td><td align="center"><a class="xref" href="#CRM-4">4</a></td><td align="center"><a class="xref" href="#CRM-4">4</a></td></tr><tr><td align="center"><a class="link" href="#class-direct-default-initargs" title="29.3.3.4. Generic Function CLOS:CLASS-DIRECT-DEFAULT-INITARGS"><code class="function">CLOS:CLASS-DIRECT-DEFAULT-INITARGS</code></a></td><td align="center"><a class="xref" href="#CRM-1">1</a></td><td align="center"><a class="xref" href="#CRM-4">4</a></td><td align="center"><a class="xref" href="#CRM-4">4</a></td></tr><tr><td align="center"><a class="link" href="#cpl" title="29.3.3.5. Generic Function CLOS:CLASS-PRECEDENCE-LIST"><code class="function">CLOS:CLASS-PRECEDENCE-LIST</code></a></td><td align="center"><a class="xref" href="#CRM-2">2</a></td><td align="center"><a class="xref" href="#CRM-3">3</a></td><td align="center"><a class="xref" href="#CRM-7">7</a></td></tr><tr><td align="center"><a class="link" href="#class-direct-subclasses" title="29.3.3.6. Generic Function CLOS:CLASS-DIRECT-SUBCLASSES"><code class="function">CLOS:CLASS-DIRECT-SUBCLASSES</code></a></td><td align="center"><a class="xref" href="#CRM-9">9</a></td><td align="center"><a class="xref" href="#CRM-9">9</a></td><td align="center"><a class="xref" href="#CRM-7">7</a></td></tr><tr><td align="center"><a class="link" href="#class-slots" title="29.3.3.7. Generic Function CLOS:CLASS-SLOTS"><code class="function">CLOS:CLASS-SLOTS</code></a></td><td align="center"><a class="xref" href="#CRM-2">2</a></td><td align="center"><a class="xref" href="#CRM-3">3</a></td><td align="center"><a class="xref" href="#CRM-4">4</a></td></tr><tr><td align="center"><a class="link" href="#class-default-initargs" title="29.3.3.8. Generic Function CLOS:CLASS-DEFAULT-INITARGS"><code class="function">CLOS:CLASS-DEFAULT-INITARGS</code></a></td><td align="center"><a class="xref" href="#CRM-2">2</a></td><td align="center"><a class="xref" href="#CRM-3">3</a></td><td align="center"><a class="xref" href="#CRM-4">4</a></td></tr><tr><td align="center"><a class="link" href="#class-finalized-p" title="29.3.3.9. Generic Function CLOS:CLASS-FINALIZED-P"><code class="function">CLOS:CLASS-FINALIZED-P</code></a></td><td align="center"><a class="xref" href="#CRM-2">2</a></td><td align="center"><a class="xref" href="#CRM-6">6</a></td><td align="center"><a class="xref" href="#CRM-5">5</a></td></tr><tr><td align="center"><a class="link" href="#class-prototype" title="29.3.3.10. Generic Function CLOS:CLASS-PROTOTYPE"><code class="function">CLOS:CLASS-PROTOTYPE</code></a></td><td align="center"><a class="xref" href="#CRM-10">10</a></td><td align="center"><a class="xref" href="#CRM-10">10</a></td><td align="center"><a class="xref" href="#CRM-10">10</a></td></tr></tbody></table></div><div class="orderedlist"><p class="title"><strong>Class Reader Methods</strong></p><ol class="orderedlist" type="1"><li class="listitem"><a id="CRM-1"></a>This method returns the value which was
   associated with the <a class="link" href="#mop-class-mo">class metaobject</a> during initialization or
   reinitialization.</li><li class="listitem"><a id="CRM-2"></a>This method returns the value associated
   with the <a class="link" href="#mop-class-mo">class metaobject</a> by <span class="method"><code class="literal"><a class="link" href="#finalize-inheritance" title="29.3.6.4. Generic Function CLOS:FINALIZE-INHERITANCE"><code class="function">CLOS:FINALIZE-INHERITANCE</code></a>
    (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>)</code></span> or
   <span class="method"><code class="literal"><a class="link" href="#finalize-inheritance" title="29.3.6.4. Generic Function CLOS:FINALIZE-INHERITANCE"><code class="function">CLOS:FINALIZE-INHERITANCE</code></a>
    (<a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>)</code></span></li><li class="listitem"><a id="CRM-3"></a>This method <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>.</li><li class="listitem"><a id="CRM-4"></a>This method returns the empty list.
 </li><li class="listitem"><a id="CRM-5"></a>This method returns true.</li><li class="listitem"><a id="CRM-6"></a>This method returns false.</li><li class="listitem"><a id="CRM-7"></a>This method returns a value derived from
   the information in <a class="xref" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes">Table 29.1, “Direct Superclass Relationships   Among The Specified Metaobject Classes”</a>, except that
   implementation-specific modifications are permitted as described in
   <a class="xref" href="#mop-ov-impl-and-user-spec" title="29.2.2.1. Implementation and User Specialization">Section 29.2.2.1, “Implementation and User Specialization”</a>.</li><li class="listitem"><a id="CRM-8"></a>This method returns the name of the
   built-in class.</li><li class="listitem"><a id="CRM-9"></a>This method returns a value which is
   maintained by <span class="method"><code class="literal"><a class="link" href="#add-direct-subclass" title="29.3.7.1. Generic Function CLOS:ADD-DIRECT-SUBCLASS"><code class="function">CLOS:ADD-DIRECT-SUBCLASS</code></a>(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>)</code></span> and <span class="method"><code class="literal"><a class="link" href="#remove-direct-subclass" title="29.3.7.2. Generic Function CLOS:REMOVE-DIRECT-SUBCLASS"><code class="function">CLOS:REMOVE-DIRECT-SUBCLASS</code></a>
    (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>)</code></span>.
   This method can be overridden only if those methods are overridden as
   well.</li><li class="listitem"><a id="CRM-10"></a>No behavior is specified for this
   method beyond that which is specified for the generic function.</li></ol></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-cl-finalization"></a>29.3.4. Class Finalization Protocol</h3></div></div></div><p>Class <strong class="first"><em class="firstterm">finalization
  <a id="class-finalization" class="indexterm"></a>
 </em></strong> is the process of computing the information a class
 inherits from its superclasses and preparing to actually allocate
 instances of the class.
The class finalization process includes computing the class's class
precedence list, the full set of slots accessible in instances of the
class and the full set of default initialization arguments for the class.
These values are associated with the <a class="link" href="#mop-class-mo">class metaobject</a> and can be accessed by
calling the appropriate reader.
In addition, the class finalization process makes decisions about how
instances of the class will be implemented.</p><p>To support forward-referenced superclasses, and to account for the
fact that not all classes are actually instantiated, class finalization
is not done as part of the initialization of the <a class="link" href="#mop-class-mo">class metaobject</a>.  Instead,
finalization is done as a separate protocol, invoked by calling the
generic function <a class="link" href="#finalize-inheritance" title="29.3.6.4. Generic Function CLOS:FINALIZE-INHERITANCE"><code class="function">CLOS:FINALIZE-INHERITANCE</code></a>.  The exact point at which
<a class="link" href="#finalize-inheritance" title="29.3.6.4. Generic Function CLOS:FINALIZE-INHERITANCE"><code class="function">CLOS:FINALIZE-INHERITANCE</code></a> is called depends on the class of the <a class="link" href="#mop-class-mo">class metaobject</a>; for
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a> it is called sometime after all the classes
superclasses are defined, but no later than when the first instance of
the class is allocated (by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_all_ate-instance.html" target="_top"><code class="function">ALLOCATE-INSTANCE</code></a>).</p><p>The first step of class finalization is computing the class
precedence list.  Doing this first allows subsequent steps to access the
class precedence list.  This step is performed by calling the generic
function <a class="link" href="#compute-cpl" title="29.3.6.10. Generic Function CLOS:COMPUTE-CLASS-PRECEDENCE-LIST"><code class="function">CLOS:COMPUTE-CLASS-PRECEDENCE-LIST</code></a>.  The value returned from this call is associated
with the <a class="link" href="#mop-class-mo">class metaobject</a> and can be accessed by calling the <a class="link" href="#cpl" title="29.3.3.5. Generic Function CLOS:CLASS-PRECEDENCE-LIST"><code class="function">CLOS:CLASS-PRECEDENCE-LIST</code></a> generic
function.</p><p>The second step is computing the full set of slots that will be
accessible in instances of the class.  This step is performed by calling
the generic function <a class="link" href="#compute-slots" title="29.3.6.11. Generic Function CLOS:COMPUTE-SLOTS"><code class="function">CLOS:COMPUTE-SLOTS</code></a>.  The result of this call is a list
of <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s.  This value is associated with the <a class="link" href="#mop-class-mo">class metaobject</a> and can
be accessed by calling the <a class="link" href="#class-slots" title="29.3.3.7. Generic Function CLOS:CLASS-SLOTS"><code class="function">CLOS:CLASS-SLOTS</code></a> generic function.</p><p>The behavior of <a class="link" href="#compute-slots" title="29.3.6.11. Generic Function CLOS:COMPUTE-SLOTS"><code class="function">CLOS:COMPUTE-SLOTS</code></a> is itself layered, consisting of
calls to <a class="link" href="#esd-class" title="29.3.6.14. Generic Function CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS"><code class="function">CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS</code></a> and <a class="link" href="#compute-esd" title="29.3.6.12. Generic Function CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION"><code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION</code></a>.</p><p>The final step of class finalization is computing the full set of
initialization arguments for the class.  This is done by calling the
generic function <a class="link" href="#compute-default-initargs" title="29.3.6.15. Generic Function CLOS:COMPUTE-DEFAULT-INITARGS"><code class="function">CLOS:COMPUTE-DEFAULT-INITARGS</code></a>.  The value returned by this
generic function is associated with the <a class="link" href="#mop-class-mo">class metaobject</a> and can be
accessed by calling <a class="link" href="#class-default-initargs" title="29.3.3.8. Generic Function CLOS:CLASS-DEFAULT-INITARGS"><code class="function">CLOS:CLASS-DEFAULT-INITARGS</code></a>.</p><p>If the class was previously finalized, <a class="link" href="#finalize-inheritance" title="29.3.6.4. Generic Function CLOS:FINALIZE-INHERITANCE"><code class="function">CLOS:FINALIZE-INHERITANCE</code></a> may
call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_mak_ces-obsolete.html" target="_top"><code class="function">MAKE-INSTANCES-OBSOLETE</code></a>.  The circumstances under which this
happens are described in the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] section
 <a class="xref" href="#redef-class" title="4.6. Redefining Classes sec_4-3-6">Section 4.6, “Redefining Classes   sec_4-3-6”</a>.</p><p>Forward-referenced classes, which provide a temporary definition
for a class which has been referenced but not yet defined, can never be
finalized.  An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if <a class="link" href="#finalize-inheritance" title="29.3.6.4. Generic Function CLOS:FINALIZE-INHERITANCE"><code class="function">CLOS:FINALIZE-INHERITANCE</code></a> is called on a
forward-referenced class.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-cl-init"></a>29.3.5. Class Initialization</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-cl-init-mo">29.3.5.1. Initialization of class metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#class-mo-init-methods">29.3.5.1.1. Methods</a></span></dt><dt><span class="section"><a href="#mop-cl-init-anon">29.3.5.1.2. Initialization of Anonymous Classes</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-cl-reinit-mo">29.3.5.2. Reinitialization of class metaobjects</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-cl-init-mo"></a>29.3.5.1. Initialization of <a class="link" href="#mop-class-mo">class metaobject</a>s</h4></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#class-mo-init-methods">29.3.5.1.1. Methods</a></span></dt><dt><span class="section"><a href="#mop-cl-init-anon">29.3.5.1.2. Initialization of Anonymous Classes</a></span></dt></dl></div><p>A <a class="link" href="#mop-class-mo">class metaobject</a> can be created by calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>.
 The initialization arguments establish the definition of the class.
 A <a class="link" href="#mop-class-mo">class metaobject</a> can be redefined by calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a>.
 Some classes of <a class="link" href="#mop-class-mo">class metaobject</a> do not support redefinition;
 in these cases, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>.</p><p>Initialization of a <a class="link" href="#mop-class-mo">class metaobject</a> must be done by calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>
and allowing it to call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a>.  Reinitialization of a
<a class="link" href="#mop-class-mo">class metaobject</a> must be done by calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a>.
 Portable programs must <span class="strong"><strong>not</strong></span></p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">... call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a> directly to
    initialize a <a class="link" href="#mop-class-mo">class metaobject</a>;</li><li class="listitem">... call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_sha_d-initialize.html" target="_top"><code class="function">SHARED-INITIALIZE</code></a> directly to
    initialize or reinitialize a <a class="link" href="#mop-class-mo">class metaobject</a>;</li><li class="listitem">... call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_change-class.html" target="_top"><code class="function">CHANGE-CLASS</code></a> to change the class of any
    <a class="link" href="#mop-class-mo">class metaobject</a> or to turn a non-class object into a
    <a class="link" href="#mop-class-mo">class metaobject</a>.</li></ul></div><p>Since metaobject classes may not be redefined,
 no behavior is specified for the result of calls to
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_upd_efined-class.html" target="_top"><code class="function">UPDATE-INSTANCE-FOR-REDEFINED-CLASS</code></a> on <a class="link" href="#mop-class-mo">class metaobject</a>s.
 Since the class of <a class="link" href="#mop-class-mo">class metaobject</a>s may not be changed,
 no behavior is specified for the result of calls to
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_upd_ferent-class.html" target="_top"><code class="function">UPDATE-INSTANCE-FOR-DIFFERENT-CLASS</code></a> on <a class="link" href="#mop-class-mo">class metaobject</a>s.</p><p>During initialization or reinitialization, each initialization
argument is checked for errors and then associated with the <a class="link" href="#mop-class-mo">class metaobject</a>.
The value can then be accessed by calling the appropriate accessor as
shown in <a class="xref" href="#class-mo-initargs" title="Table 29.2. Initialization arguments and accessors for class metaobjects">Table 29.2, “Initialization arguments and    accessors for class metaobjects”</a>.</p><p>This section begins with a description of the error checking and
processing of each initialization argument.  This is followed by a table
showing the generic functions that can be used to access the stored
initialization arguments.  Initialization behavior specific to the
different specified <a class="link" href="#mop-class-mo">class metaobject</a> classes comes next.  The section ends with a
set of restrictions on portable methods affecting <a class="link" href="#mop-class-mo">class metaobject</a> initialization
and reinitialization.</p><p>In these descriptions, the phrase <span class="quote">“<span class="quote">this argument defaults to
<em class="replaceable"><code>value</code></em></span>”</span> means that when that initialization argument is not
supplied, initialization or reinitialization is performed as if
<em class="replaceable"><code>value</code></em> had been supplied.  For some initialization arguments this
could be done by the use of default initialization arguments, but
whether it is done this way is not specified.  Implementations are free
to define default initialization arguments for specified <a class="link" href="#mop-class-mo">class metaobject</a> classes.
Portable programs are free to define default initialization arguments
for portable subclasses of the class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>.</p><p>Unless there is a specific note to the
  contrary, then during reinitialization, if an initialization argument
  is not supplied, the previously stored value is left unchanged.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p class="simpara">The <code class="constant">:DIRECT-DEFAULT-INITARGS</code> argument is a list
   of <a class="link" href="#mop-canonicalized-default-initarg">canonicalized default initialization argument</a>s.</p><p class="simpara">An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if this value is not a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#proper_list">proper list</a>, or if any
   element of the list is not a <a class="link" href="#mop-canonicalized-default-initarg">canonicalized default initialization argument</a>.</p><p class="simpara">If the <a class="link" href="#mop-class-mo">class metaobject</a> is being initialized, this argument
   defaults to the empty list.</p></li><li class="listitem"><p class="simpara"> The <code class="constant">:DIRECT-SLOTS</code> argument is a list of
   <a class="link" href="#mop-canonicalized-slot-spec">canonicalized slot specification</a>s.</p><p class="simpara">An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if this value is not a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#proper_list">proper list</a> or if any
   element of the list is not a <a class="link" href="#mop-canonicalized-slot-spec">canonicalized slot specification</a>.</p><p>After error checking, this value is converted to a
   list of <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s before it is associated with the <a class="link" href="#mop-class-mo">class metaobject</a>.  Conversion
   of each <a class="link" href="#mop-canonicalized-slot-spec">canonicalized slot specification</a> to a <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> is a two-step process.
   First, the generic function <a class="link" href="#dsd-class" title="29.3.6.9. Generic Function CLOS:DIRECT-SLOT-DEFINITION-CLASS"><code class="function">CLOS:DIRECT-SLOT-DEFINITION-CLASS</code></a> is called with the <a class="link" href="#mop-class-mo">class metaobject</a> and
   the <a class="link" href="#mop-canonicalized-slot-spec">canonicalized slot specification</a> to determine the class of the new
   <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>; this permits both the <a class="link" href="#mop-class-mo">class metaobject</a> and the
   <a class="link" href="#mop-canonicalized-slot-spec">canonicalized slot specification</a> to control the resulting <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> class.
   Second, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a> is applied to the direct <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> class and the
   <a class="link" href="#mop-canonicalized-slot-spec">canonicalized slot specification</a>.
   This conversion could be implemented as shown in the
   following code:</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defun.html" target="_top"><code class="function">DEFUN</code></a> convert-to-direct-slot-definition (class canonicalized-slot)
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_apply.html" target="_top"><code class="function">APPLY</code></a> #'<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>
         (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_apply.html" target="_top"><code class="function">APPLY</code></a> #'<a class="link" href="#dsd-class" title="29.3.6.9. Generic Function CLOS:DIRECT-SLOT-DEFINITION-CLASS"><code class="function">CLOS:DIRECT-SLOT-DEFINITION-CLASS</code></a>
                class canonicalized-slot)
         canonicalized-slot))
</pre><p class="simpara">If the <a class="link" href="#mop-class-mo">class metaobject</a> is being initialized, this argument defaults to
   the empty list.</p><p class="simpara">Once the <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s have been created, the specified reader and
   writer methods are created.  The generic functions
   <a class="link" href="#reader-method-class" title="29.7.2.1. Generic Function CLOS:READER-METHOD-CLASS"><code class="function">CLOS:READER-METHOD-CLASS</code></a> and <a class="link" href="#writer-method-class" title="29.7.2.2. Generic Function CLOS:WRITER-METHOD-CLASS"><code class="function">CLOS:WRITER-METHOD-CLASS</code></a> are called to
   determine the classes of the <a class="link" href="#mop-method-mo">method metaobject</a>s created.</p></li><li class="listitem"><p class="simpara"> The <code class="constant">:DIRECT-SUPERCLASSES</code> argument is a list of
   <a class="link" href="#mop-class-mo">class metaobject</a>s.  Classes which do not support multiple inheritance
   signal an error if the list contains more than one element.</p><p class="simpara">An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if this value is not a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#proper_list">proper list</a> or if
   <a class="link" href="#validate-superclass" title="29.3.6.7. Generic Function CLOS:VALIDATE-SUPERCLASS"><code class="function">CLOS:VALIDATE-SUPERCLASS</code></a> applied to <em class="replaceable"><code>class</code></em> and any element of this
   list returns false.</p><p class="simpara">When the <a class="link" href="#mop-class-mo">class metaobject</a> is being initialized, and this argument is
   either not supplied or is the empty list, this argument defaults as
   follows: if the class is an instance of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a> or one of
   its subclasses the default value is a list of the class
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_standard-object.html" target="_top"><code class="classname">STANDARD-OBJECT</code></a>; if the class is an instance of
   <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a> or one of its subclasses the default
   value is a list of the class
   <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-OBJECT</code></a>.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>If the class is an instance of
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_structure-class.html" target="_top"><code class="classname">STRUCTURE-CLASS</code></a> or one of its subclasses the default value is a
    list of the class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_structure-object.html" target="_top"><code class="classname">STRUCTURE-OBJECT</code></a></p></div><p class="simpara">After any defaulting of the value, the generic function
   <a class="link" href="#add-direct-subclass" title="29.3.7.1. Generic Function CLOS:ADD-DIRECT-SUBCLASS"><code class="function">CLOS:ADD-DIRECT-SUBCLASS</code></a> is called once for each element of the list.
  </p><p class="simpara">When the <a class="link" href="#mop-class-mo">class metaobject</a> is being reinitialized and this
   argument is supplied, the generic function <a class="link" href="#remove-direct-subclass" title="29.3.7.2. Generic Function CLOS:REMOVE-DIRECT-SUBCLASS"><code class="function">CLOS:REMOVE-DIRECT-SUBCLASS</code></a>
   is called once for each <a class="link" href="#mop-class-mo">class metaobject</a> in the previously stored value but not
   in the new value; the generic function <a class="link" href="#add-direct-subclass" title="29.3.7.1. Generic Function CLOS:ADD-DIRECT-SUBCLASS"><code class="function">CLOS:ADD-DIRECT-SUBCLASS</code></a> is
   called once for each <a class="link" href="#mop-class-mo">class metaobject</a> in the new value but not in the
   previously stored value.</p></li><li class="listitem">The <code class="constant">:DOCUMENTATION</code> argument is
 a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>. An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if it is not. This argument default
 to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> during initialization.</li><li class="listitem"><p class="simpara">The <code class="constant">:NAME</code> argument is an object.</p><p class="simpara">If the class is being initialized, this argument defaults to
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</p></li></ul></div><p>After the processing and defaulting of initialization arguments
described above, the value of each initialization argument is associated
with the <a class="link" href="#mop-class-mo">class metaobject</a>.  These values can then be accessed by calling
the corresponding generic function.  The correspondences are as follows:
 </p><div class="table"><a id="class-mo-initargs"></a><p class="title"><strong>Table 29.2. Initialization arguments and
   accessors for <a class="link" href="#mop-class-mo">class metaobject</a>s</strong></p><div class="table-contents"><table class="table" summary="Initialization arguments and&#10;   accessors for class metaobjects" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="center">Initialization Argument</th><th align="center">Generic Function</th></tr></thead><tbody><tr><td align="center"><code class="constant">:DIRECT-DEFAULT-INITARGS</code></td><td align="center"><a class="link" href="#class-direct-default-initargs" title="29.3.3.4. Generic Function CLOS:CLASS-DIRECT-DEFAULT-INITARGS"><code class="function">CLOS:CLASS-DIRECT-DEFAULT-INITARGS</code></a></td></tr><tr><td align="center"><code class="constant">:DIRECT-SLOTS</code></td><td align="center"><a class="link" href="#class-direct-slots" title="29.3.3.3. Generic Function CLOS:CLASS-DIRECT-SLOTS"><code class="function">CLOS:CLASS-DIRECT-SLOTS</code></a></td></tr><tr><td align="center"><code class="constant">:DIRECT-SUPERCLASSES</code></td><td align="center"><a class="link" href="#class-direct-superclasses" title="29.3.3.2. Generic Function CLOS:CLASS-DIRECT-SUPERCLASSES"><code class="function">CLOS:CLASS-DIRECT-SUPERCLASSES</code></a></td></tr><tr><td align="center"><code class="constant">:DOCUMENTATION</code></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_doc_umentationcp.html" target="_top"><code class="function">DOCUMENTATION</code></a></td></tr><tr><td align="center"><code class="constant">:NAME</code></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_class-name.html" target="_top"><code class="function">CLASS-NAME</code></a></td></tr></tbody></table></div></div><p><br class="table-break" /></p><p>Instances of the class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a> support multiple
inheritance and reinitialization.  Instances of the class
<a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a> support multiple inheritance and
reinitialization.  For <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a>es, all of the
initialization arguments default to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>Instances of the class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_structure-class.html" target="_top"><code class="classname">STRUCTURE-CLASS</code></a> do
  not support multiple inheritance and reinitialization.
</p></div><p>Since built-in classes cannot be created or reinitialized by the
user, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a>
are called to initialize or reinitialize a derived instance of the class
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_built-in-class.html" target="_top"><code class="classname">BUILT-IN-CLASS</code></a>.</p><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="class-mo-init-methods"></a>29.3.5.1.1. Methods</h5></div></div></div><p>It is not specified which methods provide the initialization and
reinitialization behavior described above.  Instead, the information
needed to allow portable programs to specialize this behavior is
presented as a set of restrictions on the methods a portable program can
define.  The model is that portable initialization methods have access
to the <a class="link" href="#mop-class-mo">class metaobject</a> when either all or none of the specified initialization
has taken effect.</p><p>These restrictions govern the methods that a portable program can
 define on the generic functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a>,
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a>, and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_sha_d-initialize.html" target="_top"><code class="function">SHARED-INITIALIZE</code></a>.
 These restrictions apply only to methods on these generic functions for
 which the first specializer is a subclass of the class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>.
 Other portable methods on these generic functions are not affected by
 these restrictions.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Portable programs must not define methods on
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_sha_d-initialize.html" target="_top"><code class="function">SHARED-INITIALIZE</code></a>.</li><li class="listitem"><p>For <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a>:
   </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; "><li class="listitem">Portable programs must not define primary methods.
 </li><li class="listitem">Portable programs may define around-methods, but
   these must be extending, not overriding methods.</li><li class="listitem">Portable before-methods must assume that when they
   are run, none of the initialization behavior described above has been
   completed.</li><li class="listitem">Portable after-methods must assume that when they
   are run, all of the initialization behavior described above has been
   completed.</li></ul></div></li></ul></div><p>The results are undefined if any of
 these restrictions are violated.</p></div><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="mop-cl-init-anon"></a>29.3.5.1.2. Initialization of Anonymous Classes</h5></div></div></div><p><a class="link" href="#mop-class-mo">class metaobject</a>s created with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a> are usually <strong class="first"><em class="firstterm">anonymous
  <a id="class-anonymous" class="indexterm"></a>
 </em></strong>; that is, they have no <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#proper_name">proper name</a>.
An anonymous <a class="link" href="#mop-class-mo">class metaobject</a> can be given a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#proper_name">proper name</a> using
<code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_find-class.html" target="_top"><code class="function">FIND-CLASS</code></a>)</code> and
<code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_class-name.html" target="_top"><code class="function">CLASS-NAME</code></a>)</code>.</p><p>When a <a class="link" href="#mop-class-mo">class metaobject</a> is created with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>, it is initialized
in the usual way.  The initialization arguments passed to
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a> are use to establish the definition of the class.  Each
initialization argument is checked for errors and associated with the
<a class="link" href="#mop-class-mo">class metaobject</a>.  The initialization arguments correspond roughly to the
arguments accepted by the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> macro, and more closely to the
arguments accepted by the <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a> function.</p><p>Some <a class="link" href="#mop-class-mo">class metaobject</a> classes allow their instances to be
 redefined.  When permissible, this is done by calling
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a>.  This is discussed in the
 <a class="link" href="#mop-cl-reinit-mo" title="29.3.5.2. Reinitialization of class metaobjects">next section</a>.</p><p>An example of creating an anonymous class directly using
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a> follows:</p><pre class="programlisting">
(flet ((zero () 0)
       (propellor () *propellor*))
  (make-instance 'standard-class
    :name '(my-class foo)
    :direct-superclasses (list (find-class 'plane)
                               another-anonymous-class)
    :direct-slots `((:name x
                     :initform 0
                     :initfunction ,#'zero
                     :initargs (:x)
                     :readers (position-x)
                     :writers ((setf position-x)))
                    (:name y
                     :initform 0
                     :initfunction ,#'zero
                     :initargs (:y)
                     :readers (position-y)
                     :writers ((setf position-y))))
    :direct-default-initargs `((:engine *propellor* ,#'propellor))))
</pre></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-cl-reinit-mo"></a>29.3.5.2. Reinitialization of <a class="link" href="#mop-class-mo">class metaobject</a>s</h4></div></div></div><p>Some <a class="link" href="#mop-class-mo">class metaobject</a> classes allow their instances to be reinitialized.
This is done by calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a>.  The initialization
arguments have the same interpretation as in class initialization.</p><p>If the <a class="link" href="#mop-class-mo">class metaobject</a> was finalized before the call to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a>,
<a class="link" href="#finalize-inheritance" title="29.3.6.4. Generic Function CLOS:FINALIZE-INHERITANCE"><code class="function">CLOS:FINALIZE-INHERITANCE</code></a> will be called again once all the initialization
arguments have been processed and associated with the <a class="link" href="#mop-class-mo">class metaobject</a>.
In addition, once finalization is complete, any dependents of the
<a class="link" href="#mop-class-mo">class metaobject</a> will be updated by calling <a class="link" href="#update-dependent" title="29.11.1.1. Generic Function CLOS:UPDATE-DEPENDENT"><code class="function">CLOS:UPDATE-DEPENDENT</code></a>.</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-cl-customize"></a>29.3.6. Customization</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#setf-class-name">29.3.6.1. Generic Function <code class="code">(SETF CLASS-NAME)</code></a></span></dt><dt><span class="section"><a href="#ensure-class">29.3.6.2. Generic Function <code class="function">CLOS:ENSURE-CLASS</code></a></span></dt><dt><span class="section"><a href="#ensure-class-UC">29.3.6.3. Generic Function <code class="function">CLOS:ENSURE-CLASS-USING-CLASS</code></a></span></dt><dt><span class="section"><a href="#finalize-inheritance">29.3.6.4. Generic Function <code class="function">CLOS:FINALIZE-INHERITANCE</code></a></span></dt><dt><span class="section"><a href="#mop-make-instance">29.3.6.5. Generic Function <code class="function">MAKE-INSTANCE</code></a></span></dt><dt><span class="section"><a href="#alloc-instance">29.3.6.6. Generic Function <code class="function">ALLOCATE-INSTANCE</code></a></span></dt><dt><span class="section"><a href="#validate-superclass">29.3.6.7. Generic Function <code class="function">CLOS:VALIDATE-SUPERCLASS</code></a></span></dt><dt><span class="section"><a href="#compute-dsd-initargs">29.3.6.8. Generic Function <code class="function">CLOS:COMPUTE-DIRECT-SLOT-DEFINITION-INITARGS</code></a></span></dt><dt><span class="section"><a href="#dsd-class">29.3.6.9. Generic Function <code class="function">CLOS:DIRECT-SLOT-DEFINITION-CLASS</code></a></span></dt><dt><span class="section"><a href="#compute-cpl">29.3.6.10. Generic Function <code class="function">CLOS:COMPUTE-CLASS-PRECEDENCE-LIST</code></a></span></dt><dt><span class="section"><a href="#compute-slots">29.3.6.11. Generic Function <code class="function">CLOS:COMPUTE-SLOTS</code></a></span></dt><dt><span class="section"><a href="#compute-esd">29.3.6.12. Generic Function <code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION</code></a></span></dt><dt><span class="section"><a href="#compute-esd-initargs">29.3.6.13. Generic Function <code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION-INITARGS</code></a></span></dt><dt><span class="section"><a href="#esd-class">29.3.6.14. Generic Function <code class="function">CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS</code></a></span></dt><dt><span class="section"><a href="#compute-default-initargs">29.3.6.15. Generic Function <code class="function">CLOS:COMPUTE-DEFAULT-INITARGS</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="setf-class-name"></a>29.3.6.1. Generic Function <a class="link" href="#setf-class-name" title="29.3.6.1. Generic Function (SETF CLASS-NAME)"><code class="code">(SETF CLASS-NAME)</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#setf-class-name" title="29.3.6.1. Generic Function (SETF CLASS-NAME)"><code class="code">(SETF CLASS-NAME)</code></a> <em class="replaceable"><code>new-name</code></em>
 <em class="replaceable"><code>class</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>class</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>new-name</code></em></span></dt><dd>any Lisp object.</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>The <em class="replaceable"><code>new-name</code></em> argument.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This function changes the name of <em class="replaceable"><code>class</code></em> to <em class="replaceable"><code>new-name</code></em>.
   This value is usually a symbol, or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if the class has no name.</p><p class="simpara">This function works by calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a> with
   <em class="replaceable"><code>class</code></em> as its first argument, the symbol <code class="constant">:NAME</code> as its second
   argument and <em class="replaceable"><code>new-name</code></em> as its third argument.
</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="ensure-class"></a>29.3.6.2. Generic Function <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a> <em class="replaceable"><code>name</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;ALLOW-OTHER-KEYS</code></a>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>name</code></em></span></dt><dd>a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>.</dd><dt><span class="term">keyword arguments</span></dt><dd>Some of the keyword arguments accepted by this
      function are actually processed by <a class="link" href="#ensure-class-UC" title="29.3.6.3. Generic Function CLOS:ENSURE-CLASS-USING-CLASS"><code class="function">CLOS:ENSURE-CLASS-USING-CLASS</code></a>,
      others are processed during initialization of the <a class="link" href="#mop-class-mo">class metaobject</a>
      (as described in <a class="xref" href="#mop-cl-init-mo" title="29.3.5.1. Initialization of class metaobjects">Section 29.3.5.1, “Initialization of class metaobjects”</a>).
</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This function is called to define or redefine a
   class with the specified name, and can be called by the user or the
   implementation.  It is the functional equivalent of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a>, and
   is called by the expansion of the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> macro.</p><p class="simpara">The behavior of this function is actually implemented by the
   generic function <a class="link" href="#ensure-class-UC" title="29.3.6.3. Generic Function CLOS:ENSURE-CLASS-USING-CLASS"><code class="function">CLOS:ENSURE-CLASS-USING-CLASS</code></a>.  When <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a> is called,
   it immediately calls <a class="link" href="#ensure-class-UC" title="29.3.6.3. Generic Function CLOS:ENSURE-CLASS-USING-CLASS"><code class="function">CLOS:ENSURE-CLASS-USING-CLASS</code></a> and returns that result as its
   own.</p><p>The first argument to <a class="link" href="#ensure-class-UC" title="29.3.6.3. Generic Function CLOS:ENSURE-CLASS-USING-CLASS"><code class="function">CLOS:ENSURE-CLASS-USING-CLASS</code></a> is computed as
   follows:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">If <em class="replaceable"><code>name</code></em> names a class (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_find-class.html" target="_top"><code class="function">FIND-CLASS</code></a> returns a
      class when called with <em class="replaceable"><code>name</code></em>) use that class.</li><li class="listitem">Otherwise use <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</li></ul></div><p>
   The second argument is <em class="replaceable"><code>name</code></em>.  The remaining arguments are the
   complete set of keyword arguments received by the <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a>
   function.</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="ensure-class-UC"></a>29.3.6.3. Generic Function <a class="link" href="#ensure-class-UC" title="29.3.6.3. Generic Function CLOS:ENSURE-CLASS-USING-CLASS"><code class="function">CLOS:ENSURE-CLASS-USING-CLASS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#ensure-class-UC" title="29.3.6.3. Generic Function CLOS:ENSURE-CLASS-USING-CLASS"><code class="function">CLOS:ENSURE-CLASS-USING-CLASS</code></a> <em class="replaceable"><code>class</code></em> <em class="replaceable"><code>name</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    <code class="constant">:DIRECT-DEFAULT-INITARGS</code> <code class="constant">:DIRECT-SLOTS</code> <code class="constant">:DIRECT-SUPERCLASSES</code>
    <code class="constant">:NAME</code> <code class="constant">:METACLASS</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;ALLOW-OTHER-KEYS</code></a>)
 </code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>class</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</dd><dt><span class="term"><em class="replaceable"><code>name</code></em></span></dt><dd>a class name.</dd><dt><span class="term"><code class="constant">:METACLASS</code></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a> class or a <a class="link" href="#mop-class-mo">class metaobject</a> class name.  If this
      argument is not supplied, it defaults to the class named
      <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>.  If a class name is supplied, it is interpreted
      as the class with that name.  If a class name is supplied, but
      there is no such class, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.</dd><dt><span class="term"><code class="constant">:DIRECT-SUPERCLASSES</code></span></dt><dd>a list of which each element is a <a class="link" href="#mop-class-mo">class metaobject</a> or a
      class name.  An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if this argument is not a
      <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#proper_list">proper list</a>.</dd><dt><span class="term">additional keyword arguments</span></dt><dd>See <a class="xref" href="#mop-cl-init-mo" title="29.3.5.1. Initialization of class metaobjects">Section 29.3.5.1, “Initialization of class metaobjects”</a>
</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function is called to define or modify
   the definition of a named class.  It is called by the <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a>
   function.  It can also be called directly.</p><p>The first step performed by this generic function is to
   compute the set of initialization arguments which will be used to
   create or reinitialize the named class.  The initialization arguments
   are computed from the full set of keyword arguments received by this
   generic function as follows:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The <code class="constant">:METACLASS</code> argument is not included in the
      initialization arguments.</li><li class="listitem"><p>If the <code class="constant">:DIRECT-SUPERCLASSES</code> argument was received
      by this generic function, it is converted into a list of <a class="link" href="#mop-class-mo">class metaobject</a>s.
      This conversion does not affect the structure of the supplied
      <code class="constant">:DIRECT-SUPERCLASSES</code> argument.  For each element in the
      <code class="constant">:DIRECT-SUPERCLASSES</code> argument:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; "><li class="listitem">If the element is a <a class="link" href="#mop-class-mo">class metaobject</a>, that
         <a class="link" href="#mop-class-mo">class metaobject</a> is used.</li><li class="listitem">If the element names a class, that <a class="link" href="#mop-class-mo">class metaobject</a> is
         used.</li><li class="listitem"><p class="simpara">Otherwise an instance of the class
         <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a> is created and used.
         The <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#proper_name">proper name</a> of the newly created forward referenced
         <a class="link" href="#mop-class-mo">class metaobject</a> is set to the element.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>A new <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a>
          instance is only created when one for the given class name
          does not yet exist; otherwise the existing one is reused.
          See <a class="xref" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP">Implementation of class <code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code> in <span class="command"><strong>CLISP</strong></span></a>.</p></div></li></ul></div></li><li class="listitem">All other keyword arguments are included directly
      in the initialization arguments.</li></ul></div><p class="simpara">If the <em class="replaceable"><code>class</code></em> argument is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, a new <a class="link" href="#mop-class-mo">class metaobject</a> is created
   by calling the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a> generic function with the value of the
   <code class="constant">:METACLASS</code> argument as its first argument, and the previously
   computed initialization arguments.  The <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#proper_name">proper name</a> of the
   newly created <a class="link" href="#mop-class-mo">class metaobject</a> is set to <em class="replaceable"><code>name</code></em>.  The newly created <a class="link" href="#mop-class-mo">class metaobject</a> is
   returned.</p><p class="simpara">If the <em class="replaceable"><code>class</code></em> argument is a <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_change-class.html" target="_top"><code class="function">CHANGE-CLASS</code></a> is called to change its class to the value specified
   by the <code class="constant">:METACLASS</code> argument.  The <a class="link" href="#mop-class-mo">class metaobject</a> is then reinitialized with
   the previously initialization arguments.  (This is a documented
   violation of the general constraint that <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_change-class.html" target="_top"><code class="function">CHANGE-CLASS</code></a> may not be
   used with <a class="link" href="#mop-class-mo">class metaobject</a>s.)</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>
    The <em class="replaceable"><code>class</code></em> argument cannot be a <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a>. See
    <a class="xref" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP">Implementation of class <code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code> in <span class="command"><strong>CLISP</strong></span></a>.</p></div><p class="simpara">If the class of the <em class="replaceable"><code>class</code></em> argument is not the same as the
   class specified by the <code class="constant">:METACLASS</code> argument, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.</p><p class="simpara">Otherwise, the <a class="link" href="#mop-class-mo">class metaobject</a> <em class="replaceable"><code>class</code></em> is redefined by calling the
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a> generic function with <em class="replaceable"><code>class</code></em> and the
   initialization arguments.  The <em class="replaceable"><code>class</code></em> argument is then
   returned.</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#ensure-class-UC" title="29.3.6.3. Generic Function CLOS:ENSURE-CLASS-USING-CLASS"><code class="function">CLOS:ENSURE-CLASS-USING-CLASS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>) <em class="replaceable"><code>name</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:METACLASS</code>
   <code class="constant">:DIRECT-SUPERCLASSES</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;ALLOW-OTHER-KEYS</code></a>)</code></span></span></dt><dd><p class="simpara">This method implements the behavior of the generic
   function in the case where the <em class="replaceable"><code>class</code></em> argument is a class.</p><p class="simpara">This method can be overridden.</p></dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#ensure-class-UC" title="29.3.6.3. Generic Function CLOS:ENSURE-CLASS-USING-CLASS"><code class="function">CLOS:ENSURE-CLASS-USING-CLASS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a>) <em class="replaceable"><code>name</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:METACLASS</code>
   <code class="constant">:DIRECT-SUPERCLASSES</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;ALLOW-OTHER-KEYS</code></a>)</code></span></span></dt><dd><p class="simpara">This method implements the behavior of the generic
   function in the case where the <em class="replaceable"><code>class</code></em> argument is a forward
   referenced class.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>This method does not exist.
   See <a class="xref" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP">Implementation of class <code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code> in <span class="command"><strong>CLISP</strong></span></a>.
   Use the method specialized on <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_null.html" target="_top"><code class="classname">NULL</code></a> instead.</p></div></dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#ensure-class-UC" title="29.3.6.3. Generic Function CLOS:ENSURE-CLASS-USING-CLASS"><code class="function">CLOS:ENSURE-CLASS-USING-CLASS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_null.html" target="_top"><code class="classname">NULL</code></a>) <em class="replaceable"><code>name</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:METACLASS</code>
   <code class="constant">:DIRECT-SUPERCLASSES</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;ALLOW-OTHER-KEYS</code></a>)</code></span></span></dt><dd>This method implements the behavior of the generic
   function in the case where the <em class="replaceable"><code>class</code></em> argument is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="finalize-inheritance"></a>29.3.6.4. Generic Function <a class="link" href="#finalize-inheritance" title="29.3.6.4. Generic Function CLOS:FINALIZE-INHERITANCE"><code class="function">CLOS:FINALIZE-INHERITANCE</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#finalize-inheritance" title="29.3.6.4. Generic Function CLOS:FINALIZE-INHERITANCE"><code class="function">CLOS:FINALIZE-INHERITANCE</code></a>
     <em class="replaceable"><code>class</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>class</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd></dl></div></dd><dt><span class="term">Values</span></dt><dd>The values returned by this generic function are unspecified.
 </dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function is called to finalize a <a class="link" href="#mop-class-mo">class metaobject</a>.
   This is described in <a class="xref" href="#mop-cl-finalization" title="29.3.4. Class Finalization Protocol">Section 29.3.4, “Class Finalization Protocol”</a>
  </p><p class="simpara">After <a class="link" href="#finalize-inheritance" title="29.3.6.4. Generic Function CLOS:FINALIZE-INHERITANCE"><code class="function">CLOS:FINALIZE-INHERITANCE</code></a> returns, the <a class="link" href="#mop-class-mo">class metaobject</a> is
   finalized and the result of calling <a class="link" href="#class-finalized-p" title="29.3.3.9. Generic Function CLOS:CLASS-FINALIZED-P"><code class="function">CLOS:CLASS-FINALIZED-P</code></a> on the <a class="link" href="#mop-class-mo">class metaobject</a>
   will be true.</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#finalize-inheritance" title="29.3.6.4. Generic Function CLOS:FINALIZE-INHERITANCE"><code class="function">CLOS:FINALIZE-INHERITANCE</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#finalize-inheritance" title="29.3.6.4. Generic Function CLOS:FINALIZE-INHERITANCE"><code class="function">CLOS:FINALIZE-INHERITANCE</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>))</code></span></span></dt><dd>No behavior is specified for these
   methods beyond that which is specified for their respective generic
   functions.</dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#finalize-inheritance" title="29.3.6.4. Generic Function CLOS:FINALIZE-INHERITANCE"><code class="function">CLOS:FINALIZE-INHERITANCE</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a>))</code></span></span></dt><dd>This method <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-make-instance"></a>29.3.6.5. Generic Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a> <em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a>
    <em class="replaceable"><code>initargs</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>class</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a> or a class name.
   </dd><dt><span class="term"><em class="replaceable"><code>initargs</code></em></span></dt><dd>a list of alternating initialization argument
      names and values.</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>A newly allocated and initialized instance of <em class="replaceable"><code>class</code></em>.
</dd><dt><span class="term">Purpose</span></dt><dd>The generic function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a> creates and
   returns a new instance of the given class.  Its behavior and use is
   described in the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>].
</dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>initargs</code></em>)</code></span></span></dt><dd>This method simply invokes <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>
   recursively on the arguments <span class="method"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_find-class.html" target="_top"><code class="function">FIND-CLASS</code></a>
   <em class="replaceable"><code>class</code></em>)</code></span> and <em class="replaceable"><code>initargs</code></em>.</dd><dt><span class="term"><span class="method"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a> (<em class="replaceable"><code>class</code></em>
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>initargs</code></em>)</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a> (<em class="replaceable"><code>class</code></em>
   <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>initargs</code></em>)</code></span></span></dt><dd>These methods implement the behavior of
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a> described in the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] section
   <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_7-1.html">7.1
    <span class="quote">“<span class="quote">Object Creation and Initialization</span>”</span></a>.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="alloc-instance"></a>29.3.6.6. Generic Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_all_ate-instance.html" target="_top"><code class="function">ALLOCATE-INSTANCE</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_all_ate-instance.html" target="_top"><code class="function">ALLOCATE-INSTANCE</code></a> <em class="replaceable"><code>class</code></em>
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>initargs</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>class</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>initargs</code></em></span></dt><dd>alternating initialization argument names and
      values.</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>A newly allocated instance of <em class="replaceable"><code>class</code></em>
</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function is called to create a new,
   uninitialized instance of a class.  The interpretation of the concept
   of an <strong class="first"><em class="firstterm">uninitialized</em></strong> instance depends on the
   <a class="link" href="#mop-class-mo">class metaobject</a> class.</p><p class="simpara">Before allocating the new instance, <a class="link" href="#class-finalized-p" title="29.3.3.9. Generic Function CLOS:CLASS-FINALIZED-P"><code class="function">CLOS:CLASS-FINALIZED-P</code></a> is
   called to see if <em class="replaceable"><code>class</code></em> has been finalized.  If it has not been
   finalized, <a class="link" href="#finalize-inheritance" title="29.3.6.4. Generic Function CLOS:FINALIZE-INHERITANCE"><code class="function">CLOS:FINALIZE-INHERITANCE</code></a> is called before the new instance
   is allocated.</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_all_ate-instance.html" target="_top"><code class="function">ALLOCATE-INSTANCE</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>initargs</code></em></code></span></span></dt><dd>This method allocates storage in the instance for
   each slot with allocation <code class="constant">:INSTANCE</code>.  These slots are unbound.
   Slots with any other allocation are ignored by this method (no
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed).</dd><dt><span class="term"><span class="method"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_all_ate-instance.html" target="_top"><code class="function">ALLOCATE-INSTANCE</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>)
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>initargs</code></em>)</code></span></span></dt><dd><p class="simpara">This method allocates storage in the instance for
   each slot with allocation <code class="constant">:INSTANCE</code>.  These slots are unbound.
   Slots with any other allocation are ignored by this method (no
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed).</p><p class="simpara">The funcallable instance function of the instance is
   undefined - the results are undefined if the instance is applied to
   arguments before <a class="link" href="#set-fif" title="29.10.3.3. Function CLOS:SET-FUNCALLABLE-INSTANCE-FUNCTION"><code class="function">CLOS:SET-FUNCALLABLE-INSTANCE-FUNCTION</code></a> has been used
   to set the funcallable instance function.
</p></dd><dt><span class="term"><span class="method"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_all_ate-instance.html" target="_top"><code class="function">ALLOCATE-INSTANCE</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_built-in-class.html" target="_top"><code class="classname">BUILT-IN-CLASS</code></a>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>initargs</code></em>)</code></span></span></dt><dd>This method <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="validate-superclass"></a>29.3.6.7. Generic Function <a class="link" href="#validate-superclass" title="29.3.6.7. Generic Function CLOS:VALIDATE-SUPERCLASS"><code class="function">CLOS:VALIDATE-SUPERCLASS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#validate-superclass" title="29.3.6.7. Generic Function CLOS:VALIDATE-SUPERCLASS"><code class="function">CLOS:VALIDATE-SUPERCLASS</code></a> <em class="replaceable"><code>class</code></em>
    <em class="replaceable"><code>superclass</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>class</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>superclass</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_boolean.html" target="_top"><code class="classname">BOOLEAN</code></a>.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function is called to determine whether
   the class <em class="replaceable"><code>superclass</code></em> is suitable for use as a superclass of
   <em class="replaceable"><code>class</code></em>.</p><p class="simpara">This generic function can be be called by the implementation
   or user code.  It is called during <a class="link" href="#mop-class-mo">class metaobject</a> initialization and
   reinitialization, before the direct superclasses are stored.  If this
   generic function returns false, the initialization or
   reinitialization will signal an error.
</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#validate-superclass" title="29.3.6.7. Generic Function CLOS:VALIDATE-SUPERCLASS"><code class="function">CLOS:VALIDATE-SUPERCLASS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>) (<em class="replaceable"><code>superclass</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>))</code></span></span></dt><dd><p>This method returns true in three situations:
  </p><div class="orderedlist"><ol class="orderedlist" type="i"><li class="listitem">If the <em class="replaceable"><code>superclass</code></em> argument is the class named <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>,
   </li><li class="listitem">if the class of the <em class="replaceable"><code>class</code></em> argument is the same
     as the class of the <em class="replaceable"><code>superclass</code></em> argument, or
   </li><li class="listitem">if the class of one of the arguments is
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a> and the class of the other is
     <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>.</li></ol></div><p>In all other cases, this method returns false.</p><p class="simpara">This method can be overridden.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>This method also returns true in a fourth situation:
   </p><div class="orderedlist"><ol class="orderedlist" start="4" type="i"><li class="listitem">If the class of the <em class="replaceable"><code>class</code></em> argument is a subclass
      of the class of the <em class="replaceable"><code>superclass</code></em> argument.
 </li></ol></div></div></dd></dl></div><p><strong>Remarks. </strong>Defining a method on <a class="link" href="#validate-superclass" title="29.3.6.7. Generic Function CLOS:VALIDATE-SUPERCLASS"><code class="function">CLOS:VALIDATE-SUPERCLASS</code></a> requires detailed
 knowledge of of the internal protocol followed by each of the two
 <a class="link" href="#mop-class-mo">class metaobject</a> classes.  A method on <a class="link" href="#validate-superclass" title="29.3.6.7. Generic Function CLOS:VALIDATE-SUPERCLASS"><code class="function">CLOS:VALIDATE-SUPERCLASS</code></a> which returns true
 for two different <a class="link" href="#mop-class-mo">class metaobject</a> classes declares that they are
 compatible.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="compute-dsd-initargs"></a>29.3.6.8. Generic Function <a class="link" href="#compute-dsd-initargs" title="29.3.6.8. Generic Function CLOS:COMPUTE-DIRECT-SLOT-DEFINITION-INITARGS"><code class="function">CLOS:COMPUTE-DIRECT-SLOT-DEFINITION-INITARGS</code></a></h4></div></div></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p></p></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#compute-dsd-initargs" title="29.3.6.8. Generic Function CLOS:COMPUTE-DIRECT-SLOT-DEFINITION-INITARGS"><code class="function">CLOS:COMPUTE-DIRECT-SLOT-DEFINITION-INITARGS</code></a> <em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a>
     <em class="replaceable"><code>slot-spec</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>class</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>slot-spec</code></em></span></dt><dd>a
       <a class="link" href="#mop-canonicalized-slot-spec">canonicalized slot specification</a>.</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>A list of initialization arguments for a <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>.
</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function determines the initialization
   arguments for the direct slot definition for a slot in a class.
   It is called during initialization of a class.  The resulting
   initialization arguments are passed to <a class="link" href="#dsd-class" title="29.3.6.9. Generic Function CLOS:DIRECT-SLOT-DEFINITION-CLASS"><code class="function">CLOS:DIRECT-SLOT-DEFINITION-CLASS</code></a> and then to
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>.</p><p class="simpara">This generic function uses the supplied <a class="link" href="#mop-canonicalized-slot-spec">canonicalized slot specification</a>.
   The value of <code class="constant">:NAME</code> in the returned initargs is the same as the value
   of <code class="constant">:NAME</code> in the supplied <em class="replaceable"><code>slot-spec</code></em> argument.
</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#compute-dsd-initargs" title="29.3.6.8. Generic Function CLOS:COMPUTE-DIRECT-SLOT-DEFINITION-INITARGS"><code class="function">CLOS:COMPUTE-DIRECT-SLOT-DEFINITION-INITARGS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>slot-spec</code></em>)</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#compute-dsd-initargs" title="29.3.6.8. Generic Function CLOS:COMPUTE-DIRECT-SLOT-DEFINITION-INITARGS"><code class="function">CLOS:COMPUTE-DIRECT-SLOT-DEFINITION-INITARGS</code></a> (<em class="replaceable"><code>class</code></em>
   <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>slot-spec</code></em>)</code></span></span></dt><dd><p class="simpara">This method returns <em class="replaceable"><code>slot-spec</code></em> unmodified.</p><p class="simpara">This method can be overridden.</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="dsd-class"></a>29.3.6.9. Generic Function <a class="link" href="#dsd-class" title="29.3.6.9. Generic Function CLOS:DIRECT-SLOT-DEFINITION-CLASS"><code class="function">CLOS:DIRECT-SLOT-DEFINITION-CLASS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#dsd-class" title="29.3.6.9. Generic Function CLOS:DIRECT-SLOT-DEFINITION-CLASS"><code class="function">CLOS:DIRECT-SLOT-DEFINITION-CLASS</code></a> <em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a>
    <em class="replaceable"><code>initargs</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>class</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>initargs</code></em></span></dt><dd>a set of initialization arguments and values.
</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>A subclass of the class <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:DIRECT-SLOT-DEFINITION</code></a>.
</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">When a class is initialized, each of the
   <a class="link" href="#mop-canonicalized-slot-spec">canonicalized slot specification</a>s must be converted to a <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>.
   This generic function is called to determine
   the class of that <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>.</p><p class="simpara">The <em class="replaceable"><code>initargs</code></em> argument is simply the
   <a class="link" href="#mop-canonicalized-slot-spec">canonicalized slot specification</a> for the slot.
</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#dsd-class" title="29.3.6.9. Generic Function CLOS:DIRECT-SLOT-DEFINITION-CLASS"><code class="function">CLOS:DIRECT-SLOT-DEFINITION-CLASS</code></a>
    (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>initargs</code></em>)</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#dsd-class" title="29.3.6.9. Generic Function CLOS:DIRECT-SLOT-DEFINITION-CLASS"><code class="function">CLOS:DIRECT-SLOT-DEFINITION-CLASS</code></a> (<em class="replaceable"><code>class</code></em>
    <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>initargs</code></em>)</code></span></span></dt><dd><p class="simpara">These methods return the class <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-DIRECT-SLOT-DEFINITION</code></a>.
  </p><p class="simpara">These methods can be overridden.</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="compute-cpl"></a>29.3.6.10. Generic Function <a class="link" href="#compute-cpl" title="29.3.6.10. Generic Function CLOS:COMPUTE-CLASS-PRECEDENCE-LIST"><code class="function">CLOS:COMPUTE-CLASS-PRECEDENCE-LIST</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#compute-cpl" title="29.3.6.10. Generic Function CLOS:COMPUTE-CLASS-PRECEDENCE-LIST"><code class="function">CLOS:COMPUTE-CLASS-PRECEDENCE-LIST</code></a>
     <em class="replaceable"><code>class</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>class</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>A list of <a class="link" href="#mop-class-mo">class metaobject</a>s.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic-function is called to determine the
   class precedence list of a class.</p><p class="simpara">The result is a list which contains each of <em class="replaceable"><code>class</code></em> and its
   superclasses once and only once.  The first element of the list is
   <em class="replaceable"><code>class</code></em> and the last element is the class named <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>.</p><p class="simpara">All methods on this generic function must compute the class
   precedence list as a function of the ordered direct superclasses of
   the superclasses of <em class="replaceable"><code>class</code></em>.  The results are undefined if the
   rules used to compute the class precedence list depend on any other
   factors.</p><p class="simpara">When a class is finalized, <a class="link" href="#finalize-inheritance" title="29.3.6.4. Generic Function CLOS:FINALIZE-INHERITANCE"><code class="function">CLOS:FINALIZE-INHERITANCE</code></a> calls this
   generic function and associates the returned value with the <a class="link" href="#mop-class-mo">class metaobject</a>.
   The value can then be accessed by calling <a class="link" href="#cpl" title="29.3.3.5. Generic Function CLOS:CLASS-PRECEDENCE-LIST"><code class="function">CLOS:CLASS-PRECEDENCE-LIST</code></a>.</p><p class="simpara">The list returned by this function
 will not be mutated by the implementation.  The results are undefined
 if a portable program mutates the list returned by this function.</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#compute-cpl" title="29.3.6.10. Generic Function CLOS:COMPUTE-CLASS-PRECEDENCE-LIST"><code class="function">CLOS:COMPUTE-CLASS-PRECEDENCE-LIST</code></a> (<em class="replaceable"><code>class</code></em>
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>))</code></span></span></dt><dd><p class="simpara">This method computes the class precedence list
   according to the rules described in the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] section
   <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_4-3-5.html">4.3.5 <span class="quote">“<span class="quote">Determining the
     Class Precedence List</span>”</span></a>.</p><p class="simpara">This method <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> if <em class="replaceable"><code>class</code></em> or any of its superclasses
  is a <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a>.</p><p class="simpara">This method can be overridden.</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="compute-slots"></a>29.3.6.11. Generic Function <a class="link" href="#compute-slots" title="29.3.6.11. Generic Function CLOS:COMPUTE-SLOTS"><code class="function">CLOS:COMPUTE-SLOTS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#compute-slots" title="29.3.6.11. Generic Function CLOS:COMPUTE-SLOTS"><code class="function">CLOS:COMPUTE-SLOTS</code></a> <em class="replaceable"><code>class</code></em>)
 </code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>class</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>A set of <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function computes a set of effective
   <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s for the class <em class="replaceable"><code>class</code></em>.  The result is a list of <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s:
   one for each slot that will be accessible in instances of <em class="replaceable"><code>class</code></em>.
  </p><p class="simpara">This generic function proceeds in 3 steps:</p><p class="simpara">The first step collects the full set of direct slot
   definitions from the superclasses of <em class="replaceable"><code>class</code></em>.</p><p class="simpara">The direct slot definitions are then collected into
   individual lists, one list for each slot name associated with any of
   the direct slot definitions.  The slot names are compared with
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typspe_eql.html" target="_top"><code class="classname">EQL</code></a>.  Each such list is then sorted into class precedence list
   order.  Direct slot definitions coming from classes earlier in the
   class precedence list of <em class="replaceable"><code>class</code></em> appear before those coming from
   classes later in the class precedence list.  For each slot name, the
   generic function <a class="link" href="#compute-esd" title="29.3.6.12. Generic Function CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION"><code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION</code></a> is called to compute an effective slot
   definition.  The result of <a class="link" href="#compute-slots" title="29.3.6.11. Generic Function CLOS:COMPUTE-SLOTS"><code class="function">CLOS:COMPUTE-SLOTS</code></a> is a list of these
   effective slot definitions, in unspecified order.</p><p class="simpara">In the final step, the location for each effective slot
   definition is set.  This is done by specified around-methods;
   portable methods cannot take over this behavior.
   For more information on the slot definition locations,
   see <a class="xref" href="#mop-sa-instance-struct" title="29.10.1. Instance Structure Protocol">Section 29.10.1, “Instance Structure Protocol”</a>.</p><p class="simpara">The list returned by this function
 will not be mutated by the implementation.  The results are undefined
 if a portable program mutates the list returned by this function.</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#compute-slots" title="29.3.6.11. Generic Function CLOS:COMPUTE-SLOTS"><code class="function">CLOS:COMPUTE-SLOTS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#compute-slots" title="29.3.6.11. Generic Function CLOS:COMPUTE-SLOTS"><code class="function">CLOS:COMPUTE-SLOTS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>)}</code></span></span></dt><dd><p class="simpara">These methods implement the specified behavior of
   the generic function.</p><p class="simpara">These methods can be overridden.</p></dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#compute-slots" title="29.3.6.11. Generic Function CLOS:COMPUTE-SLOTS"><code class="function">CLOS:COMPUTE-SLOTS</code></a>
   <code class="constant">:AROUND</code> (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#compute-slots" title="29.3.6.11. Generic Function CLOS:COMPUTE-SLOTS"><code class="function">CLOS:COMPUTE-SLOTS</code></a> <code class="constant">:AROUND</code>
   (<em class="replaceable"><code>class</code></em> <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>))</code></span></span></dt><dd>These methods implement the specified behavior of
   computing and storing slot locations.
   These methods cannot be overridden.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="compute-esd"></a>29.3.6.12. Generic Function <a class="link" href="#compute-esd" title="29.3.6.12. Generic Function CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION"><code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#compute-esd" title="29.3.6.12. Generic Function CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION"><code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION</code></a> <em class="replaceable"><code>class</code></em> <em class="replaceable"><code>name</code></em> <em class="replaceable"><code>direct-slot-definitions</code></em>)
 </code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>class</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>name</code></em></span></dt><dd>a slot name.</dd><dt><span class="term"><em class="replaceable"><code>direct-slot-definitions</code></em></span></dt><dd>an ordered list of <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s.  The most specific
      <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> appears first in the list.</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>An <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function determines the effective slot
   definition for a slot in a class.  It is called by <a class="link" href="#compute-slots" title="29.3.6.11. Generic Function CLOS:COMPUTE-SLOTS"><code class="function">CLOS:COMPUTE-SLOTS</code></a>
   once for each slot accessible in instances of <em class="replaceable"><code>class</code></em>.</p><p class="simpara">This generic function uses the supplied list of <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s to
   compute the inheritance of slot properties for a single slot.  The
   returned effective slot definition represents the result of computing
   the inheritance.  The name of the new effective slot definition is
   the same as the name of the direct slot definitions supplied.</p><p class="simpara">The class of the <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> is determined by calling
   <a class="link" href="#esd-class" title="29.3.6.14. Generic Function CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS"><code class="function">CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS</code></a>.  The effective slot definition is then created by
   calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>.  The initialization arguments passed in this
   call to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a> are used to initialize the new <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>.
   See <a class="xref" href="#mop-sd" title="29.4. Slot Definitions">Section 29.4, “Slot Definitions”</a> for details.
</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#compute-esd" title="29.3.6.12. Generic Function CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION"><code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION</code></a> (<em class="replaceable"><code>class</code></em>
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>) <em class="replaceable"><code>name</code></em> <em class="replaceable"><code>direct-slot-definitions</code></em>)</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#compute-esd" title="29.3.6.12. Generic Function CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION"><code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION</code></a> (<em class="replaceable"><code>class</code></em>
   <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>) <em class="replaceable"><code>name</code></em> <em class="replaceable"><code>direct-slot-definitions</code></em>)</code></span></span></dt><dd><p class="simpara">This method implements the
 inheritance and defaulting of slot options following the rules
 described in the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] section <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_7-5-3.html" target="_top">7.5.3 <span class="quote">“<span class="quote">Inheritance of Slots and Options</span>”</span></a>.</p><p class="simpara">This method can be extended, but the value returned by the
   extending method must be the value returned by this method.
</p></dd></dl></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>The initialization arguments that are passed
  to <a class="link" href="#esd-class" title="29.3.6.14. Generic Function CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS"><code class="function">CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a> are computed through a call to
  <a class="link" href="#compute-esd-initargs" title="29.3.6.13. Generic Function CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION-INITARGS"><code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION-INITARGS</code></a>.  It is the <a class="link" href="#compute-esd-initargs" title="29.3.6.13. Generic Function CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION-INITARGS"><code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION-INITARGS</code></a> method that
  implements the inheritance rules.</p></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="compute-esd-initargs"></a>29.3.6.13. Generic Function <a class="link" href="#compute-esd-initargs" title="29.3.6.13. Generic Function CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION-INITARGS"><code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION-INITARGS</code></a></h4></div></div></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p></p></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#compute-esd-initargs" title="29.3.6.13. Generic Function CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION-INITARGS"><code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION-INITARGS</code></a> <em class="replaceable"><code>class</code></em> <em class="replaceable"><code>direct-slot-definitions</code></em>)
 </code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>class</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>direct-slot-definitions</code></em></span></dt><dd>an ordered list of <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s.  The most specific
      <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> appears first in the list.</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>A list of initialization arguments for an <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>.
</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function determines the initialization
   arguments for the effective slot definition for a slot in a class.
   It is called by <a class="link" href="#compute-esd" title="29.3.6.12. Generic Function CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION"><code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION</code></a>.  The resulting initialization arguments
   are passed to <a class="link" href="#esd-class" title="29.3.6.14. Generic Function CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS"><code class="function">CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS</code></a> and then to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>.</p><p class="simpara">This generic function uses the supplied list of <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s to
   compute the inheritance of slot properties for a single slot.  The
   returned effective slot definition initargs represent the result of
   computing the inheritance.  The value of <code class="constant">:NAME</code> in the returned
   initargs is the same as the name of the direct slot definitions
   supplied.</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#compute-esd-initargs" title="29.3.6.13. Generic Function CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION-INITARGS"><code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION-INITARGS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>) <em class="replaceable"><code>direct-slot-definitions</code></em>)</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#compute-esd-initargs" title="29.3.6.13. Generic Function CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION-INITARGS"><code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION-INITARGS</code></a> (<em class="replaceable"><code>class</code></em>
   <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>) <em class="replaceable"><code>direct-slot-definitions</code></em>)</code></span></span></dt><dd><p class="simpara">This method implements the
 inheritance and defaulting of slot options following the rules
 described in the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] section <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_7-5-3.html" target="_top">7.5.3 <span class="quote">“<span class="quote">Inheritance of Slots and Options</span>”</span></a>.</p><p class="simpara">This method can be extended.</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="esd-class"></a>29.3.6.14. Generic Function <a class="link" href="#esd-class" title="29.3.6.14. Generic Function CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS"><code class="function">CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#esd-class" title="29.3.6.14. Generic Function CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS"><code class="function">CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS</code></a> <em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a>
    <em class="replaceable"><code>initargs</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>class</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>initargs</code></em></span></dt><dd>set of initialization arguments and values.
</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>A subclass of the class <a class="link" href="#esd-class" title="29.3.6.14. Generic Function CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS"><code class="function">CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS</code></a>.
</dd><dt><span class="term">Purpose</span></dt><dd>This generic function is called by <a class="link" href="#compute-esd" title="29.3.6.12. Generic Function CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION"><code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION</code></a> to
   determine the class of the resulting <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>.  The <em class="replaceable"><code>initargs</code></em>
   argument is the set of initialization arguments and values that will
   be passed to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a> when the <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> is created.
</dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#esd-class" title="29.3.6.14. Generic Function CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS"><code class="function">CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>initargs</code></em>)</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#esd-class" title="29.3.6.14. Generic Function CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS"><code class="function">CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS</code></a> (<em class="replaceable"><code>class</code></em>
   <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>initargs</code></em>)</code></span></span></dt><dd><p class="simpara">These methods return the class <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-EFFECTIVE-SLOT-DEFINITION</code></a>.
  </p><p class="simpara">These methods can be overridden.</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="compute-default-initargs"></a>29.3.6.15. Generic Function <a class="link" href="#compute-default-initargs" title="29.3.6.15. Generic Function CLOS:COMPUTE-DEFAULT-INITARGS"><code class="function">CLOS:COMPUTE-DEFAULT-INITARGS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#compute-default-initargs" title="29.3.6.15. Generic Function CLOS:COMPUTE-DEFAULT-INITARGS"><code class="function">CLOS:COMPUTE-DEFAULT-INITARGS</code></a>
    <em class="replaceable"><code>class</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>class</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>A list of <a class="link" href="#mop-canonicalized-default-initarg">canonicalized default initialization argument</a>s.
</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic-function is called to determine the
   default initialization arguments for a class.</p><p class="simpara">The result is a list of <a class="link" href="#mop-canonicalized-default-initarg">canonicalized default initialization argument</a>s,
  with no duplication among initialization argument names.</p><p>All methods on this generic function must compute the default
  initialization arguments as a function of only:
  </p><div class="orderedlist"><ol class="orderedlist" type="i"><li class="listitem">the class precedence list of <em class="replaceable"><code>class</code></em>,
     and</li><li class="listitem">the direct default initialization arguments of each
     class in that list.</li></ol></div><p>The results are undefined if the rules used to compute
  the default initialization arguments depend on any other factors.</p><p class="simpara">When a class is finalized, <a class="link" href="#finalize-inheritance" title="29.3.6.4. Generic Function CLOS:FINALIZE-INHERITANCE"><code class="function">CLOS:FINALIZE-INHERITANCE</code></a> calls this
  generic function and associates the returned value with the <a class="link" href="#mop-class-mo">class metaobject</a>.
  The value can then be accessed by calling
  <a class="link" href="#class-default-initargs" title="29.3.3.8. Generic Function CLOS:CLASS-DEFAULT-INITARGS"><code class="function">CLOS:CLASS-DEFAULT-INITARGS</code></a>.</p><p class="simpara">The list returned by this function
 will not be mutated by the implementation.  The results are undefined
 if a portable program mutates the list returned by this function.</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#compute-default-initargs" title="29.3.6.15. Generic Function CLOS:COMPUTE-DEFAULT-INITARGS"><code class="function">CLOS:COMPUTE-DEFAULT-INITARGS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#compute-default-initargs" title="29.3.6.15. Generic Function CLOS:COMPUTE-DEFAULT-INITARGS"><code class="function">CLOS:COMPUTE-DEFAULT-INITARGS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>))</code></span></span></dt><dd><p class="simpara">These methods compute the default initialization
   arguments according to the rules described in the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] section
   <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_7-1-3.html">7.1.3 <span class="quote">“<span class="quote">Defaulting
     of Initialization Arguments</span>”</span></a>.</p><p class="simpara">These methods signal an error if <em class="replaceable"><code>class</code></em> or any of its
   superclasses is a <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a>.</p><p class="simpara">These methods can be overridden.</p></dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-cl-dep"></a>29.3.7. Updating Dependencies</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#add-direct-subclass">29.3.7.1. Generic Function <code class="function">CLOS:ADD-DIRECT-SUBCLASS</code></a></span></dt><dt><span class="section"><a href="#remove-direct-subclass">29.3.7.2. Generic Function <code class="function">CLOS:REMOVE-DIRECT-SUBCLASS</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="add-direct-subclass"></a>29.3.7.1. Generic Function <a class="link" href="#add-direct-subclass" title="29.3.7.1. Generic Function CLOS:ADD-DIRECT-SUBCLASS"><code class="function">CLOS:ADD-DIRECT-SUBCLASS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#add-direct-subclass" title="29.3.7.1. Generic Function CLOS:ADD-DIRECT-SUBCLASS"><code class="function">CLOS:ADD-DIRECT-SUBCLASS</code></a> <em class="replaceable"><code>superclass</code></em>
    <em class="replaceable"><code>subclass</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>superclass</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>subclass</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd></dl></div></dd><dt><span class="term">Values</span></dt><dd>The values returned by this generic function are unspecified.
 </dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function is called to maintain a set of
   backpointers from a class to its direct subclasses.  This generic
   function adds <em class="replaceable"><code>subclass</code></em> to the set of direct subclasses of
   <em class="replaceable"><code>superclass</code></em>.</p><p class="simpara">When a class is initialized, this generic function is called
   once for each direct superclass of the class.</p><p class="simpara">When a class is reinitialized, this generic function is
   called once for each added direct superclass of the class.  The
   generic function <a class="link" href="#remove-direct-subclass" title="29.3.7.2. Generic Function CLOS:REMOVE-DIRECT-SUBCLASS"><code class="function">CLOS:REMOVE-DIRECT-SUBCLASS</code></a> is called once for each
   deleted direct superclass of the class.
</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#add-direct-subclass" title="29.3.7.1. Generic Function CLOS:ADD-DIRECT-SUBCLASS"><code class="function">CLOS:ADD-DIRECT-SUBCLASS</code></a>
   (<em class="replaceable"><code>superclass</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>) (<em class="replaceable"><code>subclass</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>))</code></span></span></dt><dd><p class="simpara">No behavior is specified for this
   method beyond that which is specified for the generic function.</p><p>This method cannot be overridden unless the
 following methods are overridden as well:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#remove-direct-subclass" title="29.3.7.2. Generic Function CLOS:REMOVE-DIRECT-SUBCLASS"><code class="function">CLOS:REMOVE-DIRECT-SUBCLASS</code></a>
       (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>)</code></span></li><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#class-direct-subclasses" title="29.3.3.6. Generic Function CLOS:CLASS-DIRECT-SUBCLASSES"><code class="function">CLOS:CLASS-DIRECT-SUBCLASSES</code></a>
       (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>)</code></span></li></ul></div><p>
</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="remove-direct-subclass"></a>29.3.7.2. Generic Function <a class="link" href="#remove-direct-subclass" title="29.3.7.2. Generic Function CLOS:REMOVE-DIRECT-SUBCLASS"><code class="function">CLOS:REMOVE-DIRECT-SUBCLASS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#remove-direct-subclass" title="29.3.7.2. Generic Function CLOS:REMOVE-DIRECT-SUBCLASS"><code class="function">CLOS:REMOVE-DIRECT-SUBCLASS</code></a> <em class="replaceable"><code>superclass</code></em>
    <em class="replaceable"><code>subclass</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>superclass</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>subclass</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd></dl></div></dd><dt><span class="term">Values</span></dt><dd>The values returned by this generic function are unspecified.
 </dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function is called to maintain a set of
   backpointers from a class to its direct subclasses.  It removes
   <em class="replaceable"><code>subclass</code></em> from the set of direct subclasses of <em class="replaceable"><code>superclass</code></em>.  No
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if <em class="replaceable"><code>subclass</code></em> is not in this set.</p><p class="simpara">Whenever a class is reinitialized, this generic function is
   called once with each deleted direct superclass of the class.
</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#remove-direct-subclass" title="29.3.7.2. Generic Function CLOS:REMOVE-DIRECT-SUBCLASS"><code class="function">CLOS:REMOVE-DIRECT-SUBCLASS</code></a>
   (<em class="replaceable"><code>superclass</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>) (<em class="replaceable"><code>subclass</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>))</code></span></span></dt><dd><p class="simpara">No behavior is specified for this
   method beyond that which is specified for the generic function.</p><p>This method cannot be overridden unless the
 following methods are overridden as well:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#add-direct-subclass" title="29.3.7.1. Generic Function CLOS:ADD-DIRECT-SUBCLASS"><code class="function">CLOS:ADD-DIRECT-SUBCLASS</code></a>
      (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>)</code></span></li><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#class-direct-subclasses" title="29.3.3.6. Generic Function CLOS:CLASS-DIRECT-SUBCLASSES"><code class="function">CLOS:CLASS-DIRECT-SUBCLASSES</code></a>
      (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>)</code></span></li></ul></div></dd></dl></div></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="mop-sd"></a>29.4. Slot Definitions</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-sd-inheritance">29.4.1. Inheritance Structure of slot definition metaobject Classes</a></span></dt><dt><span class="section"><a href="#mop-sd-readers">29.4.2. Introspection: Readers for slot definition metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-sd-readers-GFs">29.4.2.1. Generic Functions</a></span></dt><dd><dl><dt><span class="section"><a href="#slotdef-name">29.4.2.1.1. Generic Function <code class="function">CLOS:SLOT-DEFINITION-NAME</code></a></span></dt><dt><span class="section"><a href="#slotdef-allocation">29.4.2.1.2. Generic Function <code class="function">CLOS:SLOT-DEFINITION-ALLOCATION</code></a></span></dt><dt><span class="section"><a href="#slotdef-initform">29.4.2.1.3. Generic Function <code class="function">CLOS:SLOT-DEFINITION-INITFORM</code></a></span></dt><dt><span class="section"><a href="#slotdef-initfunction">29.4.2.1.4. Generic Function <code class="function">CLOS:SLOT-DEFINITION-INITFUNCTION</code></a></span></dt><dt><span class="section"><a href="#slotdef-type">29.4.2.1.5. Generic Function <code class="function">CLOS:SLOT-DEFINITION-TYPE</code></a></span></dt><dt><span class="section"><a href="#slotdef-initargs">29.4.2.1.6. Generic Function <code class="function">CLOS:SLOT-DEFINITION-INITARGS</code></a></span></dt></dl></dd><dt><span class="section"><a href="#slotd-mo-readers-methods">29.4.2.2. Methods</a></span></dt><dt><span class="section"><a href="#slotd-mo-readers-dsd">29.4.2.3. Readers for direct slot definition metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#slotdef-readers">29.4.2.3.1. Generic Function <code class="function">CLOS:SLOT-DEFINITION-READERS</code></a></span></dt><dt><span class="section"><a href="#slotdef-writers">29.4.2.3.2. Generic Function <code class="function">CLOS:SLOT-DEFINITION-WRITERS</code></a></span></dt></dl></dd><dt><span class="section"><a href="#slotd-mo-readers-esd">29.4.2.4. Readers for effective slot definition metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#slotdef-location">29.4.2.4.1. Generic Function <code class="function">CLOS:SLOT-DEFINITION-LOCATION</code></a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="#mop-sd-init">29.4.3. Initialization of slot definition metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#slotdef-mo-methods">29.4.3.1. Methods</a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-sd-inheritance"></a>29.4.1. Inheritance Structure of <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> Classes</h3></div></div></div><div class="figure"><a id="mop-sd-inheritance-fig"></a><p class="title"><strong>Figure 29.3. Inheritance structure of <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> classes</strong></p><div class="figure-contents"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="100%"><tr><td><img src="mop-classes-slotdef.png" width="100%" alt="Inheritance structure of slot definition metaobject classes" /></td></tr></table></div></div></div><br class="figure-break" /></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-sd-readers"></a>29.4.2. Introspection: Readers for <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-sd-readers-GFs">29.4.2.1. Generic Functions</a></span></dt><dd><dl><dt><span class="section"><a href="#slotdef-name">29.4.2.1.1. Generic Function <code class="function">CLOS:SLOT-DEFINITION-NAME</code></a></span></dt><dt><span class="section"><a href="#slotdef-allocation">29.4.2.1.2. Generic Function <code class="function">CLOS:SLOT-DEFINITION-ALLOCATION</code></a></span></dt><dt><span class="section"><a href="#slotdef-initform">29.4.2.1.3. Generic Function <code class="function">CLOS:SLOT-DEFINITION-INITFORM</code></a></span></dt><dt><span class="section"><a href="#slotdef-initfunction">29.4.2.1.4. Generic Function <code class="function">CLOS:SLOT-DEFINITION-INITFUNCTION</code></a></span></dt><dt><span class="section"><a href="#slotdef-type">29.4.2.1.5. Generic Function <code class="function">CLOS:SLOT-DEFINITION-TYPE</code></a></span></dt><dt><span class="section"><a href="#slotdef-initargs">29.4.2.1.6. Generic Function <code class="function">CLOS:SLOT-DEFINITION-INITARGS</code></a></span></dt></dl></dd><dt><span class="section"><a href="#slotd-mo-readers-methods">29.4.2.2. Methods</a></span></dt><dt><span class="section"><a href="#slotd-mo-readers-dsd">29.4.2.3. Readers for direct slot definition metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#slotdef-readers">29.4.2.3.1. Generic Function <code class="function">CLOS:SLOT-DEFINITION-READERS</code></a></span></dt><dt><span class="section"><a href="#slotdef-writers">29.4.2.3.2. Generic Function <code class="function">CLOS:SLOT-DEFINITION-WRITERS</code></a></span></dt></dl></dd><dt><span class="section"><a href="#slotd-mo-readers-esd">29.4.2.4. Readers for effective slot definition metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#slotdef-location">29.4.2.4.1. Generic Function <code class="function">CLOS:SLOT-DEFINITION-LOCATION</code></a></span></dt></dl></dd></dl></div><p>The reader generic functions which simply return information
associated with <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s are presented together here
in the format described in <a class="xref" href="#mop-cl-readers" title="29.3.3. Introspection: Readers for class metaobjects">Section 29.3.3, “Introspection: Readers for class metaobjects”</a>.</p><p>Each of the reader generic functions for <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s has the same
syntax, accepting one required argument called <em class="replaceable"><code>slot</code></em>, which must be a
<a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>; otherwise, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed. An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is also <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if the <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>
has not been initialized.</p><p>These
  generic functions can be called by the user or the implementation.</p><p>For any of these generic functions which returns a list, such lists
  will not be mutated by the implementation.  The results are undefined if a
  portable program allows such a list to be mutated.</p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-sd-readers-GFs"></a>29.4.2.1. Generic Functions</h4></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#slotdef-name">29.4.2.1.1. Generic Function <code class="function">CLOS:SLOT-DEFINITION-NAME</code></a></span></dt><dt><span class="section"><a href="#slotdef-allocation">29.4.2.1.2. Generic Function <code class="function">CLOS:SLOT-DEFINITION-ALLOCATION</code></a></span></dt><dt><span class="section"><a href="#slotdef-initform">29.4.2.1.3. Generic Function <code class="function">CLOS:SLOT-DEFINITION-INITFORM</code></a></span></dt><dt><span class="section"><a href="#slotdef-initfunction">29.4.2.1.4. Generic Function <code class="function">CLOS:SLOT-DEFINITION-INITFUNCTION</code></a></span></dt><dt><span class="section"><a href="#slotdef-type">29.4.2.1.5. Generic Function <code class="function">CLOS:SLOT-DEFINITION-TYPE</code></a></span></dt><dt><span class="section"><a href="#slotdef-initargs">29.4.2.1.6. Generic Function <code class="function">CLOS:SLOT-DEFINITION-INITARGS</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="slotdef-name"></a>29.4.2.1.1. Generic Function <a class="link" href="#slotdef-name" title="29.4.2.1.1. Generic Function CLOS:SLOT-DEFINITION-NAME"><code class="function">CLOS:SLOT-DEFINITION-NAME</code></a></h5></div><div><h6 class="subtitle"><code class="code">(<a class="link" href="#slotdef-name" title="29.4.2.1.1. Generic Function CLOS:SLOT-DEFINITION-NAME"><code class="function">CLOS:SLOT-DEFINITION-NAME</code></a> <em class="replaceable"><code>slot</code></em>)</code></h6></div></div></div><p>Returns the name of <em class="replaceable"><code>slot</code></em>.  This value is a symbol that can be
used as a variable name.  This is the value of the <code class="constant">:NAME</code>
initialization argument that was associated with the <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> during
initialization.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>The slot name does not need to be usable as a
  variable name. Slot names like <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> are perfectly valid.
</p></div></div><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="slotdef-allocation"></a>29.4.2.1.2. Generic Function <a class="link" href="#slotdef-allocation" title="29.4.2.1.2. Generic Function CLOS:SLOT-DEFINITION-ALLOCATION"><code class="function">CLOS:SLOT-DEFINITION-ALLOCATION</code></a></h5></div><div><h6 class="subtitle"><code class="code">(<a class="link" href="#slotdef-allocation" title="29.4.2.1.2. Generic Function CLOS:SLOT-DEFINITION-ALLOCATION"><code class="function">CLOS:SLOT-DEFINITION-ALLOCATION</code></a> <em class="replaceable"><code>slot</code></em>)</code></h6></div></div></div><p>Returns the allocation of <em class="replaceable"><code>slot</code></em>.  This is a symbol.  This is
the defaulted value of the <code class="constant">:ALLOCATION</code> initialization argument that
was associated with the <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> during initialization.</p></div><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="slotdef-initform"></a>29.4.2.1.3. Generic Function <a class="link" href="#slotdef-initform" title="29.4.2.1.3. Generic Function CLOS:SLOT-DEFINITION-INITFORM"><code class="function">CLOS:SLOT-DEFINITION-INITFORM</code></a></h5></div><div><h6 class="subtitle"><code class="code">(<a class="link" href="#slotdef-initform" title="29.4.2.1.3. Generic Function CLOS:SLOT-DEFINITION-INITFORM"><code class="function">CLOS:SLOT-DEFINITION-INITFORM</code></a> <em class="replaceable"><code>slot</code></em>)</code></h6></div></div></div><p>Returns the initialization form of <em class="replaceable"><code>slot</code></em>.  This can be any
form.  This is the defaulted value of the <code class="constant">:INITFORM</code> initialization
argument that was associated with the <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> during initialization.
When <em class="replaceable"><code>slot</code></em> has no initialization form, the value returned is
unspecified (however, <a class="link" href="#slotdef-initfunction" title="29.4.2.1.4. Generic Function CLOS:SLOT-DEFINITION-INITFUNCTION"><code class="function">CLOS:SLOT-DEFINITION-INITFUNCTION</code></a> is guaranteed to return
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>).</p></div><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="slotdef-initfunction"></a>29.4.2.1.4. Generic Function <a class="link" href="#slotdef-initfunction" title="29.4.2.1.4. Generic Function CLOS:SLOT-DEFINITION-INITFUNCTION"><code class="function">CLOS:SLOT-DEFINITION-INITFUNCTION</code></a></h5></div><div><h6 class="subtitle"><code class="code">(<a class="link" href="#slotdef-initfunction" title="29.4.2.1.4. Generic Function CLOS:SLOT-DEFINITION-INITFUNCTION"><code class="function">CLOS:SLOT-DEFINITION-INITFUNCTION</code></a> <em class="replaceable"><code>slot</code></em>)</code></h6></div></div></div><p>Returns the initialization function of <em class="replaceable"><code>slot</code></em>.  This value is
either a function of no arguments, or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, indicating that the slot
has no initialization function.  This is the defaulted value of the
<code class="constant">:INITFUNCTION</code> initialization argument that was associated with the
<a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> during initialization.</p></div><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="slotdef-type"></a>29.4.2.1.5. Generic Function <a class="link" href="#slotdef-type" title="29.4.2.1.5. Generic Function CLOS:SLOT-DEFINITION-TYPE"><code class="function">CLOS:SLOT-DEFINITION-TYPE</code></a></h5></div><div><h6 class="subtitle"><code class="code">(<a class="link" href="#slotdef-type" title="29.4.2.1.5. Generic Function CLOS:SLOT-DEFINITION-TYPE"><code class="function">CLOS:SLOT-DEFINITION-TYPE</code></a> <em class="replaceable"><code>slot</code></em>)</code></h6></div></div></div><p>Returns the type of <em class="replaceable"><code>slot</code></em>.  This is a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_t.html#type_specifier">type specifier</a> name.
This is the defaulted value of the <code class="constant">:TYPE</code> initialization argument that
was associated with the <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> during initialization.</p></div><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="slotdef-initargs"></a>29.4.2.1.6. Generic Function <a class="link" href="#slotdef-initargs" title="29.4.2.1.6. Generic Function CLOS:SLOT-DEFINITION-INITARGS"><code class="function">CLOS:SLOT-DEFINITION-INITARGS</code></a></h5></div><div><h6 class="subtitle"><code class="code">(<a class="link" href="#slotdef-initargs" title="29.4.2.1.6. Generic Function CLOS:SLOT-DEFINITION-INITARGS"><code class="function">CLOS:SLOT-DEFINITION-INITARGS</code></a> <em class="replaceable"><code>slot</code></em>)</code></h6></div></div></div><p>Returns the set of initialization argument keywords for <em class="replaceable"><code>slot</code></em>.
This is the defaulted value of the <code class="constant">:INITARGS</code> initialization argument
that was associated with the <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> during initialization.</p></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="slotd-mo-readers-methods"></a>29.4.2.2. Methods</h4></div></div></div><div class="variablelist"><p class="title"><strong>The specified methods for the <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> readers</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#slotdef-name" title="29.4.2.1.1. Generic Function CLOS:SLOT-DEFINITION-NAME"><code class="function">CLOS:SLOT-DEFINITION-NAME</code></a>
    (<em class="replaceable"><code>slot-definition</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-SLOT-DEFINITION</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#slotdef-allocation" title="29.4.2.1.2. Generic Function CLOS:SLOT-DEFINITION-ALLOCATION"><code class="function">CLOS:SLOT-DEFINITION-ALLOCATION</code></a>
    (<em class="replaceable"><code>slot-definition</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-SLOT-DEFINITION</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#slotdef-initform" title="29.4.2.1.3. Generic Function CLOS:SLOT-DEFINITION-INITFORM"><code class="function">CLOS:SLOT-DEFINITION-INITFORM</code></a>
    (<em class="replaceable"><code>slot-definition</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-SLOT-DEFINITION</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#slotdef-initfunction" title="29.4.2.1.4. Generic Function CLOS:SLOT-DEFINITION-INITFUNCTION"><code class="function">CLOS:SLOT-DEFINITION-INITFUNCTION</code></a>
    (<em class="replaceable"><code>slot-definition</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-SLOT-DEFINITION</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#slotdef-type" title="29.4.2.1.5. Generic Function CLOS:SLOT-DEFINITION-TYPE"><code class="function">CLOS:SLOT-DEFINITION-TYPE</code></a>
    (<em class="replaceable"><code>slot-definition</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-SLOT-DEFINITION</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#slotdef-initargs" title="29.4.2.1.6. Generic Function CLOS:SLOT-DEFINITION-INITARGS"><code class="function">CLOS:SLOT-DEFINITION-INITARGS</code></a>
    (<em class="replaceable"><code>slot-definition</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-SLOT-DEFINITION</code></a>))</code></span></span></dt><dd>No behavior is specified for these
   methods beyond that which is specified for their respective generic
   functions.</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="slotd-mo-readers-dsd"></a>29.4.2.3. Readers for <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s</h4></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#slotdef-readers">29.4.2.3.1. Generic Function <code class="function">CLOS:SLOT-DEFINITION-READERS</code></a></span></dt><dt><span class="section"><a href="#slotdef-writers">29.4.2.3.2. Generic Function <code class="function">CLOS:SLOT-DEFINITION-WRITERS</code></a></span></dt></dl></div><p>The following additional reader generic functions are defined for
 <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s.</p><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="slotdef-readers"></a>29.4.2.3.1. Generic Function <a class="link" href="#slotdef-readers" title="29.4.2.3.1. Generic Function CLOS:SLOT-DEFINITION-READERS"><code class="function">CLOS:SLOT-DEFINITION-READERS</code></a></h5></div><div><h6 class="subtitle"><code class="code">(<a class="link" href="#slotdef-readers" title="29.4.2.3.1. Generic Function CLOS:SLOT-DEFINITION-READERS"><code class="function">CLOS:SLOT-DEFINITION-READERS</code></a> <em class="replaceable"><code>direct-slot-definition</code></em>)</code></h6></div></div></div><p>Returns a (possibly empty) set of readers of the <em class="replaceable"><code>direct-slot-definition</code></em>.  This
value is a list of function names.  This is the defaulted value of the
<code class="constant">:READERS</code> initialization argument that was associated with the direct
<a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> during initialization.</p></div><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="slotdef-writers"></a>29.4.2.3.2. Generic Function <a class="link" href="#slotdef-writers" title="29.4.2.3.2. Generic Function CLOS:SLOT-DEFINITION-WRITERS"><code class="function">CLOS:SLOT-DEFINITION-WRITERS</code></a></h5></div><div><h6 class="subtitle"><code class="code">(<a class="link" href="#slotdef-writers" title="29.4.2.3.2. Generic Function CLOS:SLOT-DEFINITION-WRITERS"><code class="function">CLOS:SLOT-DEFINITION-WRITERS</code></a> <em class="replaceable"><code>direct-slot-definition</code></em>)</code></h6></div></div></div><p>Returns a (possibly empty) set of writers of the <em class="replaceable"><code>direct-slot-definition</code></em>.  This
value is a list of function names.  This is the defaulted value of the
<code class="constant">:WRITERS</code> initialization argument that was associated with the direct
<a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> during initialization.
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#slotdef-readers" title="29.4.2.3.1. Generic Function CLOS:SLOT-DEFINITION-READERS"><code class="function">CLOS:SLOT-DEFINITION-READERS</code></a>
    (<em class="replaceable"><code>direct-slot-definition</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-DIRECT-SLOT-DEFINITION</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#slotdef-writers" title="29.4.2.3.2. Generic Function CLOS:SLOT-DEFINITION-WRITERS"><code class="function">CLOS:SLOT-DEFINITION-WRITERS</code></a>
    (<em class="replaceable"><code>direct-slot-definition</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-DIRECT-SLOT-DEFINITION</code></a>))</code></span></span></dt><dd>No behavior is specified for these
   methods beyond that which is specified for their respective generic
   functions.</dd></dl></div><p>
</p></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="slotd-mo-readers-esd"></a>29.4.2.4. Readers for <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s</h4></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#slotdef-location">29.4.2.4.1. Generic Function <code class="function">CLOS:SLOT-DEFINITION-LOCATION</code></a></span></dt></dl></div><p>The following reader generic function is defined for effective
 <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s.</p><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="slotdef-location"></a>29.4.2.4.1. Generic Function <a class="link" href="#slotdef-location" title="29.4.2.4.1. Generic Function CLOS:SLOT-DEFINITION-LOCATION"><code class="function">CLOS:SLOT-DEFINITION-LOCATION</code></a></h5></div><div><h6 class="subtitle"><code class="code">(<a class="link" href="#slotdef-location" title="29.4.2.4.1. Generic Function CLOS:SLOT-DEFINITION-LOCATION"><code class="function">CLOS:SLOT-DEFINITION-LOCATION</code></a> <em class="replaceable"><code>effective-slot-definition</code></em>)</code></h6></div></div></div><p>Returns the location of <em class="replaceable"><code>effective-slot-definition</code></em>.  The meaning and interpretation
 of this value is described in <a class="xref" href="#mop-sa-instance-struct" title="29.10.1. Instance Structure Protocol">Section 29.10.1, “Instance Structure Protocol”</a>.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#slotdef-location" title="29.4.2.4.1. Generic Function CLOS:SLOT-DEFINITION-LOCATION"><code class="function">CLOS:SLOT-DEFINITION-LOCATION</code></a>
    (<em class="replaceable"><code>effective-slot-definition</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-EFFECTIVE-SLOT-DEFINITION</code></a>))</code></span></span></dt><dd>This method returns the value stored by
    <span class="method"><code class="literal"><a class="link" href="#compute-slots" title="29.3.6.11. Generic Function CLOS:COMPUTE-SLOTS"><code class="function">CLOS:COMPUTE-SLOTS</code></a> <code class="constant">:AROUND</code>
     (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>)</code></span> and
    <span class="method"><code class="literal"><a class="link" href="#compute-slots" title="29.3.6.11. Generic Function CLOS:COMPUTE-SLOTS"><code class="function">CLOS:COMPUTE-SLOTS</code></a> <code class="constant">:AROUND</code>
     (<a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>)</code></span>.
</dd></dl></div></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-sd-init"></a>29.4.3. Initialization of <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#slotdef-mo-methods">29.4.3.1. Methods</a></span></dt></dl></div><p>A <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> can be created by calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>.  The
initialization arguments establish the definition of the slot
definition.  A <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> cannot be redefined; calling
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>.</p><p>Initialization of a <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> must be done by calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>
and allowing it to call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a>.
 Portable programs must <span class="strong"><strong>not</strong></span>...</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">... call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a> directly to
    initialize a <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>;</li><li class="listitem">... call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_sha_d-initialize.html" target="_top"><code class="function">SHARED-INITIALIZE</code></a> directly to
    initialize a <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>;</li><li class="listitem">... call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_change-class.html" target="_top"><code class="function">CHANGE-CLASS</code></a> to change the class of any
    <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> or to turn a non-slot-definition object into a
    <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>.</li></ul></div><p>Since metaobject classes may not be redefined, no behavior is
 specified for the result of calls to
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_upd_efined-class.html" target="_top"><code class="function">UPDATE-INSTANCE-FOR-REDEFINED-CLASS</code></a> on <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s.  Since the class of a
 <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> cannot be changed, no behavior is specified for the result of
 calls to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_upd_ferent-class.html" target="_top"><code class="function">UPDATE-INSTANCE-FOR-DIFFERENT-CLASS</code></a> on <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s.</p><p>During initialization, each initialization argument is checked for
errors and then associated with the <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>.  The value can then be
accessed by calling the appropriate accessor as shown in
 <a class="xref" href="#slotd-mo-initargs" title="Table 29.3. Initialization arguments and accessors for slot definition metaobjects">Table 29.3, “Initialization arguments and   accessors for slot definition metaobjects”</a>.</p><p>This section begins with a description of the error checking and
processing of each initialization argument.  This is followed by a table
showing the generic functions that can be used to access the stored
initialization arguments.</p><p>In these descriptions, the phrase <span class="quote">“<span class="quote">this argument defaults to
<em class="replaceable"><code>value</code></em></span>”</span> means that when that initialization argument is not
supplied, initialization is performed as if <em class="replaceable"><code>value</code></em> had been supplied.
For some initialization arguments this could be done by the use of
default initialization arguments, but whether it is done this way is not
specified.  Implementations are free to define default initialization
arguments for specified <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> classes.  Portable programs are free to
define default initialization arguments for portable subclasses of the
class <a class="link" href="#mop-sd" title="29.4. Slot Definitions"><code class="classname">CLOS:SLOT-DEFINITION</code></a>.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p class="simpara">The <code class="constant">:NAME</code> argument is a slot name.  An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed
   if this argument is not a symbol which can be used as a variable
   name.  An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if this argument is not supplied.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>The <code class="constant">:NAME</code> argument does not need to be
    usable as a variable name. Slot names like <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> are
    perfectly valid.</p></div></li><li class="listitem">The <code class="constant">:INITFORM</code> argument is a form. The
   <code class="constant">:INITFORM</code> argument defaults to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.  An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if the
   <code class="constant">:INITFORM</code> argument is supplied, but the <code class="constant">:INITFUNCTION</code> argument
   is not supplied.</li><li class="listitem">The <code class="constant">:INITFUNCTION</code> argument is a function of zero
   arguments which, when called, evaluates the <code class="constant">:INITFORM</code> in the
   appropriate <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a>.  The <code class="constant">:INITFUNCTION</code> argument
   defaults to false.  An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if the <code class="constant">:INITFUNCTION</code> argument is
   supplied, but the <code class="constant">:INITFORM</code> argument is not supplied.</li><li class="listitem">The <code class="constant">:TYPE</code> argument is a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_t.html#type_specifier">type specifier</a> name.  An
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed otherwise.  The <code class="constant">:TYPE</code> argument defaults to the symbol <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.
 </li><li class="listitem">The <code class="constant">:ALLOCATION</code> argument is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>.  An
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed otherwise.  The <code class="constant">:ALLOCATION</code> argument defaults to the
   symbol <code class="constant">:INSTANCE</code>.</li><li class="listitem">The <code class="constant">:INITARGS</code> argument is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>s.
   An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if this argument is not a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#proper_list">proper list</a>, or if any
   element of this list is not a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>.  The <code class="constant">:INITARGS</code> argument
   defaults to the empty list.</li><li class="listitem">The <code class="constant">:READERS</code> and <code class="constant">:WRITERS</code> arguments are
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>s of function names.  An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if they are not
   <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#proper_list">proper list</a>s, or if any element is not a valid function name.
   They default to the empty list.  An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if either of these
   arguments is supplied and the metaobject is not a <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:DIRECT-SLOT-DEFINITION</code></a>.
 </li><li class="listitem">The <code class="constant">:DOCUMENTATION</code> argument is
 a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>. An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if it is not. This argument default
 to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> during initialization.</li></ul></div><p>After the processing and defaulting of initialization arguments
described above, the value of each initialization argument is associated
with the <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>.  These values can then be accessed by calling the
corresponding generic function.  The correspondences are as follows:

</p><div class="table"><a id="slotd-mo-initargs"></a><p class="title"><strong>Table 29.3. Initialization arguments and
  accessors for <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>s</strong></p><div class="table-contents"><table class="table" summary="Initialization arguments and&#10;  accessors for slot definition metaobjects" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="center">Initialization Argument</th><th align="center">Generic Function</th></tr></thead><tbody><tr><td align="center"><code class="constant">:NAME</code></td><td align="center"><a class="link" href="#slotdef-name" title="29.4.2.1.1. Generic Function CLOS:SLOT-DEFINITION-NAME"><code class="function">CLOS:SLOT-DEFINITION-NAME</code></a></td></tr><tr><td align="center"><code class="constant">:INITFORM</code></td><td align="center"><a class="link" href="#slotdef-initform" title="29.4.2.1.3. Generic Function CLOS:SLOT-DEFINITION-INITFORM"><code class="function">CLOS:SLOT-DEFINITION-INITFORM</code></a></td></tr><tr><td align="center"><code class="constant">:INITFUNCTION</code></td><td align="center"><a class="link" href="#slotdef-initfunction" title="29.4.2.1.4. Generic Function CLOS:SLOT-DEFINITION-INITFUNCTION"><code class="function">CLOS:SLOT-DEFINITION-INITFUNCTION</code></a></td></tr><tr><td align="center"><code class="constant">:TYPE</code></td><td align="center"><a class="link" href="#slotdef-type" title="29.4.2.1.5. Generic Function CLOS:SLOT-DEFINITION-TYPE"><code class="function">CLOS:SLOT-DEFINITION-TYPE</code></a></td></tr><tr><td align="center"><code class="constant">:ALLOCATION</code></td><td align="center"><a class="link" href="#slotdef-allocation" title="29.4.2.1.2. Generic Function CLOS:SLOT-DEFINITION-ALLOCATION"><code class="function">CLOS:SLOT-DEFINITION-ALLOCATION</code></a></td></tr><tr><td align="center"><code class="constant">:INITARGS</code></td><td align="center"><a class="link" href="#slotdef-initargs" title="29.4.2.1.6. Generic Function CLOS:SLOT-DEFINITION-INITARGS"><code class="function">CLOS:SLOT-DEFINITION-INITARGS</code></a></td></tr><tr><td align="center"><code class="constant">:READERS</code></td><td align="center"><a class="link" href="#slotdef-readers" title="29.4.2.3.1. Generic Function CLOS:SLOT-DEFINITION-READERS"><code class="function">CLOS:SLOT-DEFINITION-READERS</code></a></td></tr><tr><td align="center"><code class="constant">:WRITERS</code></td><td align="center"><a class="link" href="#slotdef-writers" title="29.4.2.3.2. Generic Function CLOS:SLOT-DEFINITION-WRITERS"><code class="function">CLOS:SLOT-DEFINITION-WRITERS</code></a></td></tr><tr><td align="center"><code class="constant">:DOCUMENTATION</code></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_doc_umentationcp.html" target="_top"><code class="function">DOCUMENTATION</code></a></td></tr></tbody></table></div></div><p><br class="table-break" /></p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="slotdef-mo-methods"></a>29.4.3.1. Methods</h4></div></div></div><p>It is not specified which methods provide the initialization and
reinitialization behavior described above.  Instead, the information
needed to allow portable programs to specialize this behavior is
presented as a set of restrictions on the methods a portable program can
define.  The model is that portable initialization methods have access
to the <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> when either all or none of the specified initialization
has taken effect.</p><p>These restrictions govern the methods that a portable program can
define on the generic functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a>,
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a>, and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_sha_d-initialize.html" target="_top"><code class="function">SHARED-INITIALIZE</code></a>.  These restrictions
apply only to methods on these generic functions for which the first
specializer is a subclass of the class <a class="link" href="#mop-sd" title="29.4. Slot Definitions"><code class="classname">CLOS:SLOT-DEFINITION</code></a>.  Other portable
methods on these generic functions are not affected by these
restrictions.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Portable programs must not define methods on
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_sha_d-initialize.html" target="_top"><code class="function">SHARED-INITIALIZE</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a>.</li><li class="listitem"><p>For <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a>:
   </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; "><li class="listitem">Portable programs must not define primary methods.
 </li><li class="listitem">Portable programs may define around-methods, but
   these must be extending, not overriding methods.</li><li class="listitem">Portable before-methods must assume that when they
   are run, none of the initialization behavior described above has been
   completed.</li><li class="listitem">Portable after-methods must assume that when they
   are run, all of the initialization behavior described above has been
   completed.</li></ul></div></li></ul></div><p>The results are undefined if any of
 these restrictions are violated.</p></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="mop-gf"></a>29.5. Generic Functions</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-gf-inheritance">29.5.1. Inheritance Structure of generic function metaobject Classes</a></span></dt><dt><span class="section"><a href="#mop-gf-readers">29.5.2. Introspection: Readers for generic function metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#gf-name">29.5.2.1. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-NAME</code></a></span></dt><dt><span class="section"><a href="#gf-methods">29.5.2.2. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-METHODS</code></a></span></dt><dt><span class="section"><a href="#gf-lambda-list">29.5.2.3. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-LAMBDA-LIST</code></a></span></dt><dt><span class="section"><a href="#gf-argument-precedence-order">29.5.2.4. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-ARGUMENT-PRECEDENCE-ORDER</code></a></span></dt><dt><span class="section"><a href="#gf-declarations">29.5.2.5. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-DECLARATIONS</code></a></span></dt><dt><span class="section"><a href="#gf-method-class">29.5.2.6. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-METHOD-CLASS</code></a></span></dt><dt><span class="section"><a href="#gf-method-combination">29.5.2.7. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-METHOD-COMBINATION</code></a></span></dt><dt><span class="section"><a href="#gf-name-methods">29.5.2.8. Methods</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-gf-init">29.5.3. Initialization of Generic Functions</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-gf-init-defgeneric">29.5.3.1. Macro <code class="function">DEFGENERIC</code></a></span></dt><dt><span class="section"><a href="#mop-gf-invocation">29.5.3.2. Generic Function Invocation Protocol</a></span></dt><dt><span class="section"><a href="#mop-gf-init-mo">29.5.3.3. Initialization of generic function metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#gf-mo-init-methods">29.5.3.3.1. Methods</a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="#mop-gf-customize">29.5.4. Customization</a></span></dt><dd><dl><dt><span class="section"><a href="#setf-gf-name">29.5.4.1. Generic Function <code class="code">(SETF CLOS:GENERIC-FUNCTION-NAME)</code></a></span></dt><dt><span class="section"><a href="#ensure-gf">29.5.4.2. Generic Function <code class="function">ENSURE-GENERIC-FUNCTION</code></a></span></dt><dt><span class="section"><a href="#ensure-gf-UC">29.5.4.3. Generic Function <code class="function">CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS</code></a></span></dt><dt><span class="section"><a href="#mop-add-method">29.5.4.4. Generic Function <code class="function">ADD-METHOD</code></a></span></dt><dt><span class="section"><a href="#mop-remove-method">29.5.4.5. Generic Function <code class="function">REMOVE-METHOD</code></a></span></dt><dt><span class="section"><a href="#compute-applicable-methods">29.5.4.6. Generic Function <code class="function">CLOS:COMPUTE-APPLICABLE-METHODS</code></a></span></dt><dt><span class="section"><a href="#compute-applicable-methods-UC">29.5.4.7. Generic Function <code class="function">CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES</code></a></span></dt><dt><span class="section"><a href="#compute-effective-method">29.5.4.8. Generic Function <code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD</code></a></span></dt><dt><span class="section"><a href="#compute-effective-method-as-function">29.5.4.9. Function <code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD-AS-FUNCTION</code></a></span></dt><dt><span class="section"><a href="#make-method-lambda">29.5.4.10. Generic Function <code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a></span></dt><dt><span class="section"><a href="#compute-discriminating-function">29.5.4.11. Generic Function <code class="function">CLOS:COMPUTE-DISCRIMINATING-FUNCTION</code></a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-gf-inheritance"></a>29.5.1. Inheritance Structure of <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> Classes</h3></div></div></div><div class="figure"><a id="mop-gf-inheritance-fig"></a><p class="title"><strong>Figure 29.4. Inheritance structure of <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> classes</strong></p><div class="figure-contents"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="100%"><tr><td><img src="mop-classes-genfun.png" width="100%" alt="Inheritance structure of generic function metaobject classes" /></td></tr></table></div></div></div><br class="figure-break" /></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-gf-readers"></a>29.5.2. Introspection: Readers for <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>s</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#gf-name">29.5.2.1. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-NAME</code></a></span></dt><dt><span class="section"><a href="#gf-methods">29.5.2.2. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-METHODS</code></a></span></dt><dt><span class="section"><a href="#gf-lambda-list">29.5.2.3. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-LAMBDA-LIST</code></a></span></dt><dt><span class="section"><a href="#gf-argument-precedence-order">29.5.2.4. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-ARGUMENT-PRECEDENCE-ORDER</code></a></span></dt><dt><span class="section"><a href="#gf-declarations">29.5.2.5. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-DECLARATIONS</code></a></span></dt><dt><span class="section"><a href="#gf-method-class">29.5.2.6. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-METHOD-CLASS</code></a></span></dt><dt><span class="section"><a href="#gf-method-combination">29.5.2.7. Generic Function <code class="function">CLOS:GENERIC-FUNCTION-METHOD-COMBINATION</code></a></span></dt><dt><span class="section"><a href="#gf-name-methods">29.5.2.8. Methods</a></span></dt></dl></div><p>The reader generic functions which simply return information
associated with <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>s are presented together here in the format
described in <a class="xref" href="#mop-cl-readers" title="29.3.3. Introspection: Readers for class metaobjects">Section 29.3.3, “Introspection: Readers for class metaobjects”</a>.</p><p>Each of the reader generic functions for <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>s has the same
syntax, accepting one required argument called <em class="replaceable"><code>generic-function</code></em>, which must be a
<a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>; otherwise, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.  An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is also <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if the
<a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> has not been initialized.</p><p>These
  generic functions can be called by the user or the implementation.</p><p>For any of these generic functions which returns a list, such lists
  will not be mutated by the implementation.  The results are undefined if a
  portable program allows such a list to be mutated.</p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="gf-name"></a>29.5.2.1. Generic Function <a class="link" href="#gf-name" title="29.5.2.1. Generic Function CLOS:GENERIC-FUNCTION-NAME"><code class="function">CLOS:GENERIC-FUNCTION-NAME</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#gf-name" title="29.5.2.1. Generic Function CLOS:GENERIC-FUNCTION-NAME"><code class="function">CLOS:GENERIC-FUNCTION-NAME</code></a> <em class="replaceable"><code>generic-function</code></em>)</code></h5></div></div></div><p>Returns the name of the generic function, or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if the generic
function has no name.  This is the defaulted value of the <code class="constant">:NAME</code>
initialization argument that was associated with the <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> during
initialization or reinitialization.
 (See also <a class="link" href="#setf-gf-name" title="29.5.4.1. Generic Function (SETF CLOS:GENERIC-FUNCTION-NAME)"><code class="code">(SETF CLOS:GENERIC-FUNCTION-NAME)</code></a>.)</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="gf-methods"></a>29.5.2.2. Generic Function <a class="link" href="#gf-methods" title="29.5.2.2. Generic Function CLOS:GENERIC-FUNCTION-METHODS"><code class="function">CLOS:GENERIC-FUNCTION-METHODS</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#gf-methods" title="29.5.2.2. Generic Function CLOS:GENERIC-FUNCTION-METHODS"><code class="function">CLOS:GENERIC-FUNCTION-METHODS</code></a> <em class="replaceable"><code>generic-function</code></em>)</code></h5></div></div></div><p>Returns the set of methods currently connected to the generic
function.  This is a set of <a class="link" href="#mop-method-mo">method metaobject</a>s.  This value is maintained by the
generic functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_add-method.html" target="_top"><code class="function">ADD-METHOD</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_remove-method.html" target="_top"><code class="function">REMOVE-METHOD</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="gf-lambda-list"></a>29.5.2.3. Generic Function <a class="link" href="#gf-lambda-list" title="29.5.2.3. Generic Function CLOS:GENERIC-FUNCTION-LAMBDA-LIST"><code class="function">CLOS:GENERIC-FUNCTION-LAMBDA-LIST</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#gf-lambda-list" title="29.5.2.3. Generic Function CLOS:GENERIC-FUNCTION-LAMBDA-LIST"><code class="function">CLOS:GENERIC-FUNCTION-LAMBDA-LIST</code></a> <em class="replaceable"><code>generic-function</code></em>)</code></h5></div></div></div><p>Returns the <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> of the generic function.  This is the
defaulted value of the <code class="constant">:LAMBDA-LIST</code> initialization argument that was
associated with the <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> during initialization or reinitialization.
An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if the <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> has yet to be supplied.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="gf-argument-precedence-order"></a>29.5.2.4. Generic Function <a class="link" href="#gf-argument-precedence-order" title="29.5.2.4. Generic Function CLOS:GENERIC-FUNCTION-ARGUMENT-PRECEDENCE-ORDER"><code class="function">CLOS:GENERIC-FUNCTION-ARGUMENT-PRECEDENCE-ORDER</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#gf-argument-precedence-order" title="29.5.2.4. Generic Function CLOS:GENERIC-FUNCTION-ARGUMENT-PRECEDENCE-ORDER"><code class="function">CLOS:GENERIC-FUNCTION-ARGUMENT-PRECEDENCE-ORDER</code></a> <em class="replaceable"><code>generic-function</code></em>)</code></h5></div></div></div><p>Returns the argument precedence order of the generic function.
This value is a list of symbols, a permutation of the required
parameters in the <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> of the generic function.  This is the
defaulted value of the <code class="constant">:ARGUMENT-PRECEDENCE-ORDER</code> initialization
argument that was associated with the <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> during initialization or
reinitialization.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if the <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> has not yet been
  supplied.</p></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="gf-declarations"></a>29.5.2.5. Generic Function <a class="link" href="#gf-declarations" title="29.5.2.5. Generic Function CLOS:GENERIC-FUNCTION-DECLARATIONS"><code class="function">CLOS:GENERIC-FUNCTION-DECLARATIONS</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#gf-declarations" title="29.5.2.5. Generic Function CLOS:GENERIC-FUNCTION-DECLARATIONS"><code class="function">CLOS:GENERIC-FUNCTION-DECLARATIONS</code></a> <em class="replaceable"><code>generic-function</code></em>)</code></h5></div></div></div><p>Returns a possibly empty list of the <span class="quote">“<span class="quote">declarations</span>”</span>
of the generic function.  The elements of this list are
<a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_d.html#declaration_specifier">declaration specifier</a>s.  This list is the defaulted value of the
<code class="constant">:DECLARATIONS</code> initialization argument that was associated with the
<a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> during initialization or reinitialization.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="gf-method-class"></a>29.5.2.6. Generic Function <a class="link" href="#gf-method-class" title="29.5.2.6. Generic Function CLOS:GENERIC-FUNCTION-METHOD-CLASS"><code class="function">CLOS:GENERIC-FUNCTION-METHOD-CLASS</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#gf-method-class" title="29.5.2.6. Generic Function CLOS:GENERIC-FUNCTION-METHOD-CLASS"><code class="function">CLOS:GENERIC-FUNCTION-METHOD-CLASS</code></a> <em class="replaceable"><code>generic-function</code></em>)</code></h5></div></div></div><p>Returns the default method class of the generic function.  This
class must be a subclass of the class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a>.  This is the defaulted
value of the <code class="constant">:METHOD-CLASS</code> initialization argument that was
associated with the <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> during initialization or reinitialization.
</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="gf-method-combination"></a>29.5.2.7. Generic Function <a class="link" href="#gf-method-combination" title="29.5.2.7. Generic Function CLOS:GENERIC-FUNCTION-METHOD-COMBINATION"><code class="function">CLOS:GENERIC-FUNCTION-METHOD-COMBINATION</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#gf-method-combination" title="29.5.2.7. Generic Function CLOS:GENERIC-FUNCTION-METHOD-COMBINATION"><code class="function">CLOS:GENERIC-FUNCTION-METHOD-COMBINATION</code></a> <em class="replaceable"><code>generic-function</code></em>)</code></h5></div></div></div><p>Returns the method combination of the generic function.  This is a
<a class="link" href="#mop-meth-comp-mo">method combination metaobject</a>.  This is the defaulted value of the <code class="constant">:METHOD-COMBINATION</code>
initialization argument that was associated with the <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> during
initialization or reinitialization.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="gf-name-methods"></a>29.5.2.8. Methods</h4></div></div></div><div class="variablelist"><p class="title"><strong>The specified methods for the <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> reader generic
  functions</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#gf-name" title="29.5.2.1. Generic Function CLOS:GENERIC-FUNCTION-NAME"><code class="function">CLOS:GENERIC-FUNCTION-NAME</code></a>
   (<em class="replaceable"><code>generic-function</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#gf-lambda-list" title="29.5.2.3. Generic Function CLOS:GENERIC-FUNCTION-LAMBDA-LIST"><code class="function">CLOS:GENERIC-FUNCTION-LAMBDA-LIST</code></a>
   (<em class="replaceable"><code>generic-function</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#gf-argument-precedence-order" title="29.5.2.4. Generic Function CLOS:GENERIC-FUNCTION-ARGUMENT-PRECEDENCE-ORDER"><code class="function">CLOS:GENERIC-FUNCTION-ARGUMENT-PRECEDENCE-ORDER</code></a>
   (<em class="replaceable"><code>generic-function</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#gf-declarations" title="29.5.2.5. Generic Function CLOS:GENERIC-FUNCTION-DECLARATIONS"><code class="function">CLOS:GENERIC-FUNCTION-DECLARATIONS</code></a>
   (<em class="replaceable"><code>generic-function</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#gf-method-class" title="29.5.2.6. Generic Function CLOS:GENERIC-FUNCTION-METHOD-CLASS"><code class="function">CLOS:GENERIC-FUNCTION-METHOD-CLASS</code></a>
   (<em class="replaceable"><code>generic-function</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#gf-method-combination" title="29.5.2.7. Generic Function CLOS:GENERIC-FUNCTION-METHOD-COMBINATION"><code class="function">CLOS:GENERIC-FUNCTION-METHOD-COMBINATION</code></a>
   (<em class="replaceable"><code>generic-function</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>))</code></span></span></dt><dd>No behavior is specified for these
   methods beyond that which is specified for their respective generic
   functions.</dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#gf-methods" title="29.5.2.2. Generic Function CLOS:GENERIC-FUNCTION-METHODS"><code class="function">CLOS:GENERIC-FUNCTION-METHODS</code></a>
   (<em class="replaceable"><code>generic-function</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>))</code></span></span></dt><dd><p class="simpara">No behavior is specified for this
   method beyond that which is specified for the generic function.</p><p class="simpara">The value returned by this method is maintained by
   <span class="method"><code class="literal"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_add-method.html" target="_top"><code class="function">ADD-METHOD</code></a>(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-method.html" target="_top"><code class="classname">STANDARD-METHOD</code></a>)</code></span> and
   <span class="method"><code class="literal"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_remove-method.html" target="_top"><code class="function">REMOVE-METHOD</code></a>(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-method.html" target="_top"><code class="classname">STANDARD-METHOD</code></a>)</code></span>.</p></dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-gf-init"></a>29.5.3. Initialization of Generic Functions</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-gf-init-defgeneric">29.5.3.1. Macro <code class="function">DEFGENERIC</code></a></span></dt><dt><span class="section"><a href="#mop-gf-invocation">29.5.3.2. Generic Function Invocation Protocol</a></span></dt><dt><span class="section"><a href="#mop-gf-init-mo">29.5.3.3. Initialization of generic function metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#gf-mo-init-methods">29.5.3.3.1. Methods</a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-gf-init-defgeneric"></a>29.5.3.1. Macro <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a></h4></div></div></div><p>The evaluation or execution of a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a> form results in a
call to the <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a> function. The arguments received by <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a>
are derived from the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a> form in a defined way.  As with
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a>, the exact macro-expansion of the
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a> form is not defined, only the relationship between the
arguments to the macro and the arguments received by <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a>.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The <em class="replaceable"><code>function-name</code></em>
argument to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a> becomes the first argument to <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a>.
This is the only positional argument accepted by <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a>; all other
arguments are keyword arguments.</li><li class="listitem">The <em class="replaceable"><code>lambda-list</code></em> argument to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a> becomes the value
 of the <code class="constant">:LAMBDA-LIST</code> keyword argument to <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a>.</li><li class="listitem"><p class="simpara">For each of the options <code class="constant">:ARGUMENT-PRECEDENCE-ORDER</code>,
<code class="constant">:DOCUMENTATION</code>, <code class="constant">:GENERIC-FUNCTION-CLASS</code> and <code class="constant">:METHOD-CLASS</code>, the value of the
option becomes the value of the keyword argument with the same name.
If the option does not appear in the macro form, the keyword argument
does not appear in the resulting call to <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a>.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>If the option does not appear in the macro form,
  the keyword argument appears in the resulting call to <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a>, with a
  default value: the <em class="replaceable"><code>lambda-list</code></em> for <code class="constant">:ARGUMENT-PRECEDENCE-ORDER</code>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> for
  <code class="constant">:DOCUMENTATION</code>, the class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a> for <code class="constant">:GENERIC-FUNCTION-CLASS</code>,
  the class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-method.html" target="_top"><code class="classname">STANDARD-METHOD</code></a> for <code class="constant">:METHOD-CLASS</code>.
  This is needed to make the generic function reflect the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a> form.
</p></div></li><li class="listitem"><p class="simpara">For the option <code class="constant">:DECLARE</code>, the list
of <span class="quote">“<span class="quote">declarations</span>”</span> becomes the value of the <code class="constant">:DECLARATIONS</code>
keyword argument.  If the <code class="constant">:DECLARE</code> option does not
appear in the macro form, the <code class="constant">:DECLARATIONS</code> keyword argument does not
appear in the call to <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a>.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>If the <code class="constant">:DECLARE</code> option does not appear in
  the macro form, the <code class="constant">:DECLARATIONS</code> keyword argument appears in the
  resulting call to <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a>, with a default value of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.  This is
  needed to make the generic function reflect the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a> form.
 </p></div></li><li class="listitem"><p class="simpara">The handling of the <code class="constant">:METHOD-COMBINATION</code> option is
not specified.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>If the <code class="constant">:METHOD-COMBINATION</code> option does not
  appear in the macro form, the <code class="constant">:METHOD-COMBINATION</code> keyword argument
  still appears in the resulting call to <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a>, but in a position
  where it can be overridden by user-defined initargs and default initargs.
 </p></div></li><li class="listitem"><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>The <code class="constant">:DECLARE</code> keyword is
  recognized as equivalent to the <code class="constant">:DECLARATIONS</code> keyword, for
  compatibility with <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a> in [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>].  If both <code class="constant">:DECLARE</code> and
  <code class="constant">:DECLARATIONS</code> keyword arguments are specified, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.</p><p>Any other generic function options become the value of
   keyword arguments with the same name. The value of the keyword
   argument is the tail of the generic function option. An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if
   any generic function option appears more than once in the
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a> form.</p><p>The default initargs of the
   <em class="replaceable"><code>generic-function-class</code></em> are added at the
   end of the list of arguments to pass to <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a>. This is needed to
   make the generic function reflect the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a> form.</p></div></li><li class="listitem"><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p><a id="mop-defgeneric-user-options"></a><strong>User-defined options. </strong>Any other options become the value of keyword arguments with
    the same name.  The value of the keyword argument is the tail of the
    option.  An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if any option appears more than once in the
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a> form.</p></div></li></ul></div><p>The result of the call to <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a> is returned as the result of
evaluating or executing the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a> form.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-gf-invocation"></a>29.5.3.2. Generic Function Invocation Protocol</h4></div></div></div><p>Associated with each generic function is its discriminating
function.  Each time the generic function is called, the discriminating
function is called to provide the behavior of the generic function.  The
discriminating function receives the full set of arguments received by
the generic function.  It must lookup and execute the appropriate
methods, and return the appropriate values.</p><p>The discriminating function is computed by the highest layer of
the generic function invocation protocol, <a class="link" href="#compute-discriminating-function" title="29.5.4.11. Generic Function CLOS:COMPUTE-DISCRIMINATING-FUNCTION"><code class="function">CLOS:COMPUTE-DISCRIMINATING-FUNCTION</code></a>.
Whenever a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> is initialized, reinitialized, or a method is added or
removed, the discriminating function is recomputed.
The new discriminating function is then stored with
<a class="link" href="#set-fif" title="29.10.3.3. Function CLOS:SET-FUNCALLABLE-INSTANCE-FUNCTION"><code class="function">CLOS:SET-FUNCALLABLE-INSTANCE-FUNCTION</code></a>.</p><p>Discriminating functions call <a class="link" href="#compute-applicable-methods" title="29.5.4.6. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS</code></a>
and <a class="link" href="#compute-applicable-methods-UC" title="29.5.4.7. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES</code></a> to compute the methods
applicable to the generic functions arguments.
Applicable methods are combined by <a class="link" href="#compute-effective-method" title="29.5.4.8. Generic Function CLOS:COMPUTE-EFFECTIVE-METHOD"><code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD</code></a> to
produce an <strong class="first"><em class="firstterm">effective method
  <a id="effective-method" class="indexterm"></a></em></strong>.
Provisions are made to allow memoization of the method applicability and
effective methods computations.  (See the description of
<a class="link" href="#compute-discriminating-function" title="29.5.4.11. Generic Function CLOS:COMPUTE-DISCRIMINATING-FUNCTION"><code class="function">CLOS:COMPUTE-DISCRIMINATING-FUNCTION</code></a> for details.)</p><p>The body of method definitions are processed by <a class="link" href="#make-method-lambda" title="29.5.4.10. Generic Function CLOS:MAKE-METHOD-LAMBDA"><code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a>.
The result of this generic function is a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-3.html">lambda expression</a>
which is processed by either <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile.html" target="_top"><code class="function">COMPILE</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile-file.html" target="_top"><code class="function">COMPILE-FILE</code></a> to produce a
 <strong class="first"><em class="firstterm">method function<a id="me-func" class="indexterm"></a></em></strong>.
The arguments received by the method function are controlled by the
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locmac_call-m__make-method.html" target="_top"><code class="function">CALL-METHOD</code></a> forms appearing in the effective methods.
By default, method functions accept two arguments: a list of arguments
to the generic function, and a list of next methods.
The list of next methods corresponds to the next methods argument to
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locmac_call-m__make-method.html" target="_top"><code class="function">CALL-METHOD</code></a>.
If <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locmac_call-m__make-method.html" target="_top"><code class="function">CALL-METHOD</code></a> appears with additional arguments, these will be passed
to the method functions as well; in these cases, <a class="link" href="#make-method-lambda" title="29.5.4.10. Generic Function CLOS:MAKE-METHOD-LAMBDA"><code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a>
must have created the method lambdas to expect additional arguments.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>See <a class="xref" href="#no-make-method-lambda" title="The generic function CLOS:MAKE-METHOD-LAMBDA is not implemented">The generic function <code class="function">CLOS:MAKE-METHOD-LAMBDA</code> is not implemented</a>.</p><p>See <a class="xref" href="#method-functions-args" title="Method function arguments">Method function arguments</a>.</p></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-gf-init-mo"></a>29.5.3.3. Initialization of <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>s</h4></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#gf-mo-init-methods">29.5.3.3.1. Methods</a></span></dt></dl></div><p>A <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> can be created by calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>.  The
initialization arguments establish the definition of the generic
function.  A <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> can be redefined by calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a>.
Some classes of <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> do not support redefinition; in these cases,
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>.</p><p>Initialization of a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> must be done by calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>
and allowing it to call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a>.  Reinitialization of a
<a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> must be done by calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a>.
 Portable programs must <span class="strong"><strong>not</strong></span></p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">... call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a> directly to
    initialize a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>;</li><li class="listitem">... call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_sha_d-initialize.html" target="_top"><code class="function">SHARED-INITIALIZE</code></a> directly to
    initialize or reinitialize a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>;</li><li class="listitem">... call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_change-class.html" target="_top"><code class="function">CHANGE-CLASS</code></a> to change the class of any
    <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> or to turn a non-generic-function object into a
    <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>.</li></ul></div><p>Since metaobject classes may not be redefined,
 no behavior is specified for the result of calls to
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_upd_efined-class.html" target="_top"><code class="function">UPDATE-INSTANCE-FOR-REDEFINED-CLASS</code></a> on <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>s.
 Since the class of a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> may not be changed,
 no behavior is specified for the results of calls to
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_upd_ferent-class.html" target="_top"><code class="function">UPDATE-INSTANCE-FOR-DIFFERENT-CLASS</code></a> on <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>s.</p><p>During initialization or reinitialization, each initialization
argument is checked for errors and then associated with the <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>.
The value can then be accessed by calling the appropriate accessor as
shown in <a class="xref" href="#gf-mo-initargs" title="Table 29.4. Initialization arguments and accessors for generic function metaobjects">Table 29.4, “Initialization arguments and accessors   for generic function metaobjects”</a>.</p><p>This section begins with a description of the error checking and
processing of each initialization argument.  This is followed by a table
showing the generic functions that can be used to access the stored
initialization arguments. The section ends with a set of restrictions on
portable methods affecting <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> initialization and reinitialization.</p><p>In these descriptions, the phrase <span class="quote">“<span class="quote">this argument defaults to
<em class="replaceable"><code>value</code></em></span>”</span> means that when that initialization argument is not
supplied, initialization or reinitialization is performed as if
<em class="replaceable"><code>value</code></em> had been supplied.  For some initialization arguments this
could be done by the use of default initialization arguments, but
whether it is done this way is not specified.  Implementations are free
to define default initialization arguments for specified <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> classes.
Portable programs are free to define default initialization arguments
for portable subclasses of the class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_generic-function.html" target="_top"><code class="classname">GENERIC-FUNCTION</code></a>.</p><p>Unless there is a specific note to the
  contrary, then during reinitialization, if an initialization argument
  is not supplied, the previously stored value is left unchanged.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p class="simpara">The <code class="constant">:ARGUMENT-PRECEDENCE-ORDER</code> argument is a list
   of symbols.</p><p class="simpara">An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if this argument appears but the <code class="constant">:LAMBDA-LIST</code>
   argument does not appear.  An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if this value is not a
   <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#proper_list">proper list</a> or if this value is not a permutation of the
   symbols from the required arguments part of the <code class="constant">:LAMBDA-LIST</code>
   initialization argument.</p><p class="simpara">When the generic function is being initialized or
   reinitialized, and this argument is not supplied, but the
   <code class="constant">:LAMBDA-LIST</code> argument is supplied, this value defaults to the
   symbols from the required arguments part of the <code class="constant">:LAMBDA-LIST</code>
   argument, in the order they appear in that argument.  If neither
   argument is supplied, neither are initialized (see the description of
   <code class="constant">:LAMBDA-LIST</code>.)</p></li><li class="listitem"><p class="simpara">The <code class="constant">:DECLARATIONS</code> argument is a list of <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_d.html#declaration_specifier">declaration specifier</a>s.
  </p><p class="simpara">An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if this value is not a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#proper_list">proper list</a> or
   if each of its elements is not a legal <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_d.html#declaration_specifier">declaration specifier</a>.</p><p class="simpara">When the generic function is being initialized, and this
   argument is not supplied, it defaults to the empty list.
 </p></li><li class="listitem">The <code class="constant">:DOCUMENTATION</code> argument is
 a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>. An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if it is not. This argument default
 to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> during initialization.</li><li class="listitem"><p class="simpara">The <code class="constant">:LAMBDA-LIST</code> argument is a <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a>.</p><p class="simpara">An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if this value is not a proper generic function
   <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a>.</p><p class="simpara">When the generic function is being initialized, and this
   argument is not supplied, the generic function's <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> is not
   initialized.  The <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> will be initialized later, either when
   the first method is added to the generic function, or a later
   reinitialization of the generic function.</p></li><li class="listitem">The <code class="constant">:METHOD-COMBINATION</code> argument is a <a class="link" href="#mop-meth-comp-mo">method combination metaobject</a>.
 </li><li class="listitem"><p class="simpara">The <code class="constant">:METHOD-CLASS</code> argument is a <a class="link" href="#mop-class-mo">class metaobject</a>.
  </p><p class="simpara">An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if this value is not a subclass of the
   class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a>.</p><p class="simpara">When the generic function is being initialized, and this
   argument is not supplied, it defaults to the class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-method.html" target="_top"><code class="classname">STANDARD-METHOD</code></a>.
 </p></li><li class="listitem"><p class="simpara">  The <code class="constant">:NAME</code> argument is an object.</p><p class="simpara">If the generic function is being initialized, this argument
   defaults to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
</p></li></ul></div><p>After the processing and defaulting of initialization arguments
described above, the value of each initialization argument is associated
with the <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>.  These values can then be accessed by calling the
corresponding generic function.  The correspondences are as follows:
</p><div class="table"><a id="gf-mo-initargs"></a><p class="title"><strong>Table 29.4. Initialization arguments and accessors
  for <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>s</strong></p><div class="table-contents"><table class="table" summary="Initialization arguments and accessors&#10;  for generic function metaobjects" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="center">Initialization Argument</th><th align="center">Generic Function</th></tr></thead><tbody><tr><td align="center"><code class="constant">:ARGUMENT-PRECEDENCE-ORDER</code></td><td align="center"><a class="link" href="#gf-argument-precedence-order" title="29.5.2.4. Generic Function CLOS:GENERIC-FUNCTION-ARGUMENT-PRECEDENCE-ORDER"><code class="function">CLOS:GENERIC-FUNCTION-ARGUMENT-PRECEDENCE-ORDER</code></a></td></tr><tr><td align="center"><code class="constant">:DECLARATIONS</code></td><td align="center"><a class="link" href="#gf-declarations" title="29.5.2.5. Generic Function CLOS:GENERIC-FUNCTION-DECLARATIONS"><code class="function">CLOS:GENERIC-FUNCTION-DECLARATIONS</code></a></td></tr><tr><td align="center"><code class="constant">:DOCUMENTATION</code></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_doc_umentationcp.html" target="_top"><code class="function">DOCUMENTATION</code></a></td></tr><tr><td align="center"><code class="constant">:LAMBDA-LIST</code></td><td align="center"><a class="link" href="#gf-lambda-list" title="29.5.2.3. Generic Function CLOS:GENERIC-FUNCTION-LAMBDA-LIST"><code class="function">CLOS:GENERIC-FUNCTION-LAMBDA-LIST</code></a></td></tr><tr><td align="center"><code class="constant">:METHOD-COMBINATION</code></td><td align="center"><a class="link" href="#gf-method-combination" title="29.5.2.7. Generic Function CLOS:GENERIC-FUNCTION-METHOD-COMBINATION"><code class="function">CLOS:GENERIC-FUNCTION-METHOD-COMBINATION</code></a></td></tr><tr><td align="center"><code class="constant">:METHOD-CLASS</code></td><td align="center"><a class="link" href="#gf-method-class" title="29.5.2.6. Generic Function CLOS:GENERIC-FUNCTION-METHOD-CLASS"><code class="function">CLOS:GENERIC-FUNCTION-METHOD-CLASS</code></a></td></tr><tr><td align="center"><code class="constant">:NAME</code></td><td align="center"><a class="link" href="#gf-name" title="29.5.2.1. Generic Function CLOS:GENERIC-FUNCTION-NAME"><code class="function">CLOS:GENERIC-FUNCTION-NAME</code></a></td></tr></tbody></table></div></div><p><br class="table-break" /></p><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="gf-mo-init-methods"></a>29.5.3.3.1. Methods</h5></div></div></div><p>It is not specified which methods provide the initialization and
reinitialization behavior described above.  Instead, the information
needed to allow portable programs to specialize this behavior is
presented as a set of restrictions on the methods a portable program can
define.  The model is that portable initialization methods have access
to the <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> when either all or none of the specified initialization
has taken effect.</p><p>These restrictions govern the methods that a portable program can
define on the generic functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a>,
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a>, and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_sha_d-initialize.html" target="_top"><code class="function">SHARED-INITIALIZE</code></a>.  These restrictions
apply only to methods on these generic functions for which the first
specializer is a subclass of the class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_generic-function.html" target="_top"><code class="classname">GENERIC-FUNCTION</code></a>.  Other
portable methods on these generic functions are not affected by these
restrictions.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Portable programs must not define methods on
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_sha_d-initialize.html" target="_top"><code class="function">SHARED-INITIALIZE</code></a>.</li><li class="listitem"><p>For <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a>:
   </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; "><li class="listitem">Portable programs must not define primary methods.
 </li><li class="listitem">Portable programs may define around-methods, but
   these must be extending, not overriding methods.</li><li class="listitem">Portable before-methods must assume that when they
   are run, none of the initialization behavior described above has been
   completed.</li><li class="listitem">Portable after-methods must assume that when they
   are run, all of the initialization behavior described above has been
   completed.</li></ul></div></li></ul></div><p>The results are undefined if any of
 these restrictions are violated.</p></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-gf-customize"></a>29.5.4. Customization</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#setf-gf-name">29.5.4.1. Generic Function <code class="code">(SETF CLOS:GENERIC-FUNCTION-NAME)</code></a></span></dt><dt><span class="section"><a href="#ensure-gf">29.5.4.2. Generic Function <code class="function">ENSURE-GENERIC-FUNCTION</code></a></span></dt><dt><span class="section"><a href="#ensure-gf-UC">29.5.4.3. Generic Function <code class="function">CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS</code></a></span></dt><dt><span class="section"><a href="#mop-add-method">29.5.4.4. Generic Function <code class="function">ADD-METHOD</code></a></span></dt><dt><span class="section"><a href="#mop-remove-method">29.5.4.5. Generic Function <code class="function">REMOVE-METHOD</code></a></span></dt><dt><span class="section"><a href="#compute-applicable-methods">29.5.4.6. Generic Function <code class="function">CLOS:COMPUTE-APPLICABLE-METHODS</code></a></span></dt><dt><span class="section"><a href="#compute-applicable-methods-UC">29.5.4.7. Generic Function <code class="function">CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES</code></a></span></dt><dt><span class="section"><a href="#compute-effective-method">29.5.4.8. Generic Function <code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD</code></a></span></dt><dt><span class="section"><a href="#compute-effective-method-as-function">29.5.4.9. Function <code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD-AS-FUNCTION</code></a></span></dt><dt><span class="section"><a href="#make-method-lambda">29.5.4.10. Generic Function <code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a></span></dt><dt><span class="section"><a href="#compute-discriminating-function">29.5.4.11. Generic Function <code class="function">CLOS:COMPUTE-DISCRIMINATING-FUNCTION</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="setf-gf-name"></a>29.5.4.1. Generic Function <a class="link" href="#setf-gf-name" title="29.5.4.1. Generic Function (SETF CLOS:GENERIC-FUNCTION-NAME)"><code class="code">(SETF CLOS:GENERIC-FUNCTION-NAME)</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#setf-gf-name" title="29.5.4.1. Generic Function (SETF CLOS:GENERIC-FUNCTION-NAME)"><code class="code">(SETF CLOS:GENERIC-FUNCTION-NAME)</code></a> <em class="replaceable"><code>new-name</code></em> <em class="replaceable"><code>generic-function</code></em>)
</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>generic-function</code></em></span></dt><dd>a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>new-name</code></em></span></dt><dd>a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_f.html#function_name">function name</a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>The <em class="replaceable"><code>new-name</code></em> argument.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This function changes the name of <em class="replaceable"><code>generic-function</code></em> to <em class="replaceable"><code>new-name</code></em>.
   This value is usually a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_f.html#function_name">function name</a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, if the generic function
   is to have no name.</p><p class="simpara">This function works by calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a> with
   <em class="replaceable"><code>generic-function</code></em> as its first argument, the symbol <code class="constant">:NAME</code> as its second argument
   and <em class="replaceable"><code>new-name</code></em> as its third argument.
</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="ensure-gf"></a>29.5.4.2. Generic Function <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a> <em class="replaceable"><code>function-name</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;ALLOW-OTHER-KEYS</code></a>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>function-name</code></em></span></dt><dd>a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_f.html#function_name">function name</a></dd><dt><span class="term">keyword arguments</span></dt><dd>Some of the keyword arguments accepted by this
      function are actually processed by <a class="link" href="#ensure-gf-UC" title="29.5.4.3. Generic Function CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS"><code class="function">CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS</code></a>, others are
      processed during initialization of the <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>
      (as described in <a class="xref" href="#mop-gf-init-mo" title="29.5.3.3. Initialization of generic function metaobjects">Section 29.5.3.3, “Initialization of generic function metaobjects”</a>).
</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>A <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This function is called to define a globally named
   generic function or to specify or modify options and declarations
   that pertain to a globally named generic function as a whole.  It can
   be called by the user or the implementation.</p><p class="simpara">It is the functional equivalent of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a>, and is
   called by the expansion of the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a> macros.
  </p><p class="simpara">The behavior of this function is actually
   implemented by the generic function <a class="link" href="#ensure-gf-UC" title="29.5.4.3. Generic Function CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS"><code class="function">CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS</code></a>.  When <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a>
   is called, it immediately calls <a class="link" href="#ensure-gf-UC" title="29.5.4.3. Generic Function CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS"><code class="function">CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS</code></a> and returns that
   result as its own.</p><p>The first argument to <a class="link" href="#ensure-gf-UC" title="29.5.4.3. Generic Function CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS"><code class="function">CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS</code></a> is computed as follows:
   </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">If <em class="replaceable"><code>function-name</code></em> names a non-generic
      function, a macro, or a special form, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.
    </li><li class="listitem">If <em class="replaceable"><code>function-name</code></em> names a generic function, that
      <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> is used.</li><li class="listitem">Otherwise, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> is used.
   </li></ul></div><p class="simpara">The second argument is <em class="replaceable"><code>function-name</code></em>.  The remaining arguments
   are the complete set of keyword arguments received by <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a>.
</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="ensure-gf-UC"></a>29.5.4.3. Generic Function <a class="link" href="#ensure-gf-UC" title="29.5.4.3. Generic Function CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS"><code class="function">CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#ensure-gf-UC" title="29.5.4.3. Generic Function CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS"><code class="function">CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS</code></a> <em class="replaceable"><code>generic-function</code></em> <em class="replaceable"><code>function-name</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    <code class="constant">:ARGUMENT-PRECEDENCE-ORDER</code> <code class="constant">:DECLARATIONS</code> <code class="constant">:DOCUMENTATION</code>
    <code class="constant">:GENERIC-FUNCTION-CLASS</code> <code class="constant">:LAMBDA-LIST</code> <code class="constant">:METHOD-CLASS</code> <code class="constant">:METHOD-COMBINATION</code>
    <code class="constant">:NAME</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;ALLOW-OTHER-KEYS</code></a>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>generic-function</code></em></span></dt><dd>a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</dd><dt><span class="term"><em class="replaceable"><code>function-name</code></em></span></dt><dd>a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_f.html#function_name">function name</a></dd><dt><span class="term"><code class="constant">:GENERIC-FUNCTION-CLASS</code></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a> or a class name.
      If it is not supplied, it defaults to the class named
      <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>.  If a class name is supplied, it is
      interpreted as the class with that name.  If a class name is
      supplied, but there is no such class, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.
   </dd><dt><span class="term">additional keyword arguments</span></dt><dd><p class="simpara">see <a class="xref" href="#mop-gf-init-mo" title="29.5.3.3. Initialization of generic function metaobjects">Section 29.5.3.3, “Initialization of generic function metaobjects”</a>.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>The <code class="constant">:DECLARE</code> keyword is recognized as
       equivalent to the <code class="constant">:DECLARATIONS</code> keyword, for compatibility
       with <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a> in [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>].</p></div></dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>A <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">The generic function <a class="link" href="#ensure-gf-UC" title="29.5.4.3. Generic Function CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS"><code class="function">CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS</code></a> is called to
   define or modify the definition of a globally named generic function.
   It is called by the <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a> function.  It can also be called
   directly.</p><p>The first step performed by this generic function is to compute
   the set of initialization arguments which will be used to create or
   reinitialize the globally named generic function.  These
   initialization arguments are computed from the full set of keyword
   arguments received by this generic function as follows:
   </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The <code class="constant">:GENERIC-FUNCTION-CLASS</code>
      argument is not included in the initialization arguments.
    </li><li class="listitem">If the <code class="constant">:METHOD-CLASS</code> argument was received by
      this generic function, it is converted into a <a class="link" href="#mop-class-mo">class metaobject</a>.
      This is done by looking up the class name with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_find-class.html" target="_top"><code class="function">FIND-CLASS</code></a>.  If
      there is no such class, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.</li><li class="listitem">All other keyword arguments are included directly
      in the initialization arguments.</li></ul></div><p class="simpara">If the <em class="replaceable"><code>generic-function</code></em> argument is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, an instance of the class
   specified by the <code class="constant">:GENERIC-FUNCTION-CLASS</code> argument is created by
   calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a> with the previously computed initialization
   arguments.  The function name <em class="replaceable"><code>function-name</code></em> is set to name the generic
   function.  The newly created <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> is returned.
  </p><p class="simpara">If the class of the <em class="replaceable"><code>generic-function</code></em> argument is not the same
   as the class specified by the <code class="constant">:GENERIC-FUNCTION-CLASS</code> argument, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>The description of <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a> in [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>]
   specifies that in this case, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_change-class.html" target="_top"><code class="function">CHANGE-CLASS</code></a> is called if the class of the
   <em class="replaceable"><code>generic-function</code></em> argument and the class specified by the <code class="constant">:GENERIC-FUNCTION-CLASS</code> argument are
   compatible. Given the description of <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a>, this also applies to the
   <a class="link" href="#ensure-gf-UC" title="29.5.4.3. Generic Function CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS"><code class="function">CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS</code></a> function. <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>'s implementation calls <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_change-class.html" target="_top"><code class="function">CHANGE-CLASS</code></a>
   always, and leaves it to the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_change-class.html" target="_top"><code class="function">CHANGE-CLASS</code></a> function to signal an error if
   needed.</p></div><p class="simpara">Otherwise the generic function <em class="replaceable"><code>generic-function</code></em> is redefined by calling
   the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a> generic function with <em class="replaceable"><code>generic-function</code></em> and the
   initialization arguments.  The <em class="replaceable"><code>generic-function</code></em> argument is then returned.
</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#ensure-gf-UC" title="29.5.4.3. Generic Function CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS"><code class="function">CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS</code></a>
   (<em class="replaceable"><code>generic-function</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_generic-function.html" target="_top"><code class="classname">GENERIC-FUNCTION</code></a>) <em class="replaceable"><code>function-name</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   <code class="constant">:GENERIC-FUNCTION-CLASS</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;ALLOW-OTHER-KEYS</code></a>)</code></span></span></dt><dd><p class="simpara">This method implements the behavior of the generic
   function in the case where <em class="replaceable"><code>function-name</code></em> names an existing generic
   function.</p><p class="simpara">This method can be overridden.</p></dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#ensure-gf-UC" title="29.5.4.3. Generic Function CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS"><code class="function">CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS</code></a>
   (<em class="replaceable"><code>generic-function</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_null.html" target="_top"><code class="classname">NULL</code></a>) <em class="replaceable"><code>function-name</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:GENERIC-FUNCTION-CLASS</code>
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;ALLOW-OTHER-KEYS</code></a>)</code></span></span></dt><dd>This method implements the behavior of the generic
   function in the case where <em class="replaceable"><code>function-name</code></em> names no function, generic
   function, macro or special form.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-add-method"></a>29.5.4.4. Generic Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_add-method.html" target="_top"><code class="function">ADD-METHOD</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_add-method.html" target="_top"><code class="function">ADD-METHOD</code></a> <em class="replaceable"><code>generic-function</code></em> <em class="replaceable"><code>method</code></em>)
 </code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>generic-function</code></em></span></dt><dd>a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>method</code></em></span></dt><dd>a <a class="link" href="#mop-method-mo">method metaobject</a>.</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>The <em class="replaceable"><code>generic-function</code></em> argument.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function associates an unattached
   method with a generic function.</p><p class="simpara">An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if the <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> of the method is not
   congruent with the <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> of the generic function.</p><p class="simpara">An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if the method is already associated with some
   other generic function.</p><p class="simpara">If the given method agrees with an existing method of the
   generic function on parameter specializers and qualifiers, the
   existing method is removed by calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_remove-method.html" target="_top"><code class="function">REMOVE-METHOD</code></a> before the
   new method is added.  See the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] section
   <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_7-6-3.html">7.6.3 <span class="quote">“<span class="quote">Agreement on
     Parameter Specializers and Qualifiers</span>”</span></a>
   for a definition of agreement in this context.</p><p>Associating the method with the generic function then
   proceeds in four steps:</p><div class="orderedlist"><ol class="orderedlist" type="i"><li class="listitem">add <em class="replaceable"><code>method</code></em> to the set returned by
      <a class="link" href="#gf-methods" title="29.5.2.2. Generic Function CLOS:GENERIC-FUNCTION-METHODS"><code class="function">CLOS:GENERIC-FUNCTION-METHODS</code></a> and arrange for <a class="link" href="#method-gf" title="29.6.2.4. Generic Function CLOS:METHOD-GENERIC-FUNCTION"><code class="function">CLOS:METHOD-GENERIC-FUNCTION</code></a> to return <em class="replaceable"><code>generic-function</code></em>;
    </li><li class="listitem">call <a class="link" href="#add-direct-method" title="29.8.4.3. Generic Function CLOS:ADD-DIRECT-METHOD"><code class="function">CLOS:ADD-DIRECT-METHOD</code></a> for each of the method's
    specializers;</li><li class="listitem">call <a class="link" href="#compute-discriminating-function" title="29.5.4.11. Generic Function CLOS:COMPUTE-DISCRIMINATING-FUNCTION"><code class="function">CLOS:COMPUTE-DISCRIMINATING-FUNCTION</code></a> and
      install its result with <a class="link" href="#set-fif" title="29.10.3.3. Function CLOS:SET-FUNCALLABLE-INSTANCE-FUNCTION"><code class="function">CLOS:SET-FUNCALLABLE-INSTANCE-FUNCTION</code></a>; and
    </li><li class="listitem">update the dependents of the generic function.
  </li></ol></div><p class="simpara">The generic function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_add-method.html" target="_top"><code class="function">ADD-METHOD</code></a> can be called by the user
   or the implementation.</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_add-method.html" target="_top"><code class="function">ADD-METHOD</code></a>
   (<em class="replaceable"><code>generic-function</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>)
   (<em class="replaceable"><code>method</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-method.html" target="_top"><code class="classname">STANDARD-METHOD</code></a>))</code></span></span></dt><dd>No behavior is specified for this
   method beyond that which is specified for the generic function.</dd><dt><span class="term"><span class="method"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_add-method.html" target="_top"><code class="function">ADD-METHOD</code></a>
   (<em class="replaceable"><code>generic-function</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>)
   (<em class="replaceable"><code>method</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a>))</code></span></span></dt><dd>This method is specified by [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>].
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-remove-method"></a>29.5.4.5. Generic Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_remove-method.html" target="_top"><code class="function">REMOVE-METHOD</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_remove-method.html" target="_top"><code class="function">REMOVE-METHOD</code></a> <em class="replaceable"><code>generic-function</code></em> <em class="replaceable"><code>method</code></em>)
</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>generic-function</code></em></span></dt><dd>a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>method</code></em></span></dt><dd>a <a class="link" href="#mop-method-mo">method metaobject</a>.</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>The <em class="replaceable"><code>generic-function</code></em> argument.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function breaks the association between
   a generic function and one of its methods.</p><p class="simpara">No <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if the method is not among the methods of the
   generic function.</p><p>Breaking the association between the method and the generic
   function proceeds in four steps:</p><div class="orderedlist"><ol class="orderedlist" type="i"><li class="listitem">remove <em class="replaceable"><code>method</code></em> from the set returned by
      <a class="link" href="#gf-methods" title="29.5.2.2. Generic Function CLOS:GENERIC-FUNCTION-METHODS"><code class="function">CLOS:GENERIC-FUNCTION-METHODS</code></a> and arrange for <a class="link" href="#method-gf" title="29.6.2.4. Generic Function CLOS:METHOD-GENERIC-FUNCTION"><code class="function">CLOS:METHOD-GENERIC-FUNCTION</code></a> to return <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>;
    </li><li class="listitem">call <a class="link" href="#remove-direct-method" title="29.8.4.4. Generic Function CLOS:REMOVE-DIRECT-METHOD"><code class="function">CLOS:REMOVE-DIRECT-METHOD</code></a> for each of the
      method's specializers;</li><li class="listitem">call <a class="link" href="#compute-discriminating-function" title="29.5.4.11. Generic Function CLOS:COMPUTE-DISCRIMINATING-FUNCTION"><code class="function">CLOS:COMPUTE-DISCRIMINATING-FUNCTION</code></a> and
      install its result with <a class="link" href="#set-fif" title="29.10.3.3. Function CLOS:SET-FUNCALLABLE-INSTANCE-FUNCTION"><code class="function">CLOS:SET-FUNCALLABLE-INSTANCE-FUNCTION</code></a>;
      and</li><li class="listitem">update the dependents of the generic function.
  </li></ol></div><p class="simpara">The generic function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_remove-method.html" target="_top"><code class="function">REMOVE-METHOD</code></a> can be called by the
   user or the implementation.
</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_remove-method.html" target="_top"><code class="function">REMOVE-METHOD</code></a>
   (<em class="replaceable"><code>generic-function</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>)
   (<em class="replaceable"><code>method</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-method.html" target="_top"><code class="classname">STANDARD-METHOD</code></a>))</code></span></span></dt><dd>No behavior is specified for this
   method beyond that which is specified for the generic function.</dd><dt><span class="term"><span class="method"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_remove-method.html" target="_top"><code class="function">REMOVE-METHOD</code></a>
   (<em class="replaceable"><code>generic-function</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>)
   (<em class="replaceable"><code>method</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a>))</code></span></span></dt><dd>This method is specified by [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>].
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="compute-applicable-methods"></a>29.5.4.6. Generic Function <a class="link" href="#compute-applicable-methods" title="29.5.4.6. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#compute-applicable-methods" title="29.5.4.6. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS</code></a>
     <em class="replaceable"><code>generic-function</code></em> <em class="replaceable"><code>arguments</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>generic-function</code></em></span></dt><dd>a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>arguments</code></em></span></dt><dd>a list of objects.</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>A possibly empty list of <a class="link" href="#mop-method-mo">method metaobject</a>s.
</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function determines the method
   applicability of a generic function given a list of required
   arguments.  The returned list of <a class="link" href="#mop-method-mo">method metaobject</a>s is sorted by
   precedence order with the most specific method appearing first.  If
   no methods are applicable to the supplied arguments the empty list is
   returned.</p><p class="simpara">When a generic function is invoked, the
   discriminating function must determine the ordered list of methods
   applicable to the arguments.  Depending on the generic function and
   the arguments, this is done in one of three ways: using a memoized
   value; calling <a class="link" href="#compute-applicable-methods-UC" title="29.5.4.7. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES</code></a>; or calling
   <a class="link" href="#compute-applicable-methods" title="29.5.4.6. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS</code></a>.
   (Refer to the description of <a class="link" href="#compute-discriminating-function" title="29.5.4.11. Generic Function CLOS:COMPUTE-DISCRIMINATING-FUNCTION"><code class="function">CLOS:COMPUTE-DISCRIMINATING-FUNCTION</code></a> for
   the details of this process.)</p><p class="simpara">The <em class="replaceable"><code>arguments</code></em> argument is permitted to contain more elements
   than the generic function accepts required arguments; in these cases
   the extra arguments will be ignored.  An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if <em class="replaceable"><code>arguments</code></em>
   contains fewer elements than the generic function accepts required
   arguments.</p><p class="simpara">The list returned by this function
 will not be mutated by the implementation.  The results are undefined
 if a portable program mutates the list returned by this function.</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#compute-applicable-methods" title="29.5.4.6. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS</code></a>
   (<em class="replaceable"><code>generic-function</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>) <em class="replaceable"><code>arguments</code></em>)</code></span></span></dt><dd><p class="simpara">This method <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> if any method of the generic
   function has a specializer which is neither a <a class="link" href="#mop-class-mo">class metaobject</a> nor an
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typspe_eql.html" target="_top"><code class="classname">EQL</code></a> specializer metaobject.</p><p class="simpara">Otherwise, this method computes the sorted list of applicable
   methods according to the rules described in the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] section
   <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_7-6-6.html">7.6.6 <span class="quote">“<span class="quote">Method Selection
     and Combination</span>”</span></a></p><p class="simpara">This method can be overridden.  Because of the consistency
   requirements between this generic function and
   <a class="link" href="#compute-applicable-methods-UC" title="29.5.4.7. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES</code></a>, doing so may require also overriding
   <span class="method"><code class="literal"><a class="link" href="#compute-applicable-methods-UC" title="29.5.4.7. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES</code></a>
    (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</code></span>.
</p></dd></dl></div><p><a id="mop-cam-remarks"></a><strong>Remarks. </strong>See also the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_com_able-methods.html" target="_top"><code class="function">COMPUTE-APPLICABLE-METHODS</code></a>.
</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="compute-applicable-methods-UC"></a>29.5.4.7. Generic Function <a class="link" href="#compute-applicable-methods-UC" title="29.5.4.7. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#compute-applicable-methods-UC" title="29.5.4.7. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES</code></a>
    <em class="replaceable"><code>generic-function</code></em> <em class="replaceable"><code>classes</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>generic-function</code></em></span></dt><dd>a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>classes</code></em></span></dt><dd>a list of <a class="link" href="#mop-class-mo">class metaobject</a>s.
</dd></dl></div></dd><dt><span class="term">Values</span></dt><dd><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">A possibly empty list of <a class="link" href="#mop-method-mo">method metaobject</a>s.
   </li><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_boolean.html" target="_top"><code class="classname">BOOLEAN</code></a></li></ol></div></dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function is called to attempt to
   determine the method applicability of a generic function given only
   the classes of the required arguments.</p><p class="simpara">If it is possible to completely determine the ordered list of
   applicable methods based only on the supplied classes, this generic
   function returns that list as its <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#primary_value">primary value</a> and true as its second
   value.  The returned list of <a class="link" href="#mop-method-mo">method metaobject</a>s is sorted by
   precedence order, the most specific method coming first.  If no
   methods are applicable to arguments with the specified classes, the
   empty list and true are returned.</p><p class="simpara">If it is not possible to completely determine the ordered
   list of applicable methods based only on the supplied classes, this
   generic function returns an unspecified <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#primary_value">primary value</a> and false as its
   second value.</p><p class="simpara">When a generic function is invoked, the
   discriminating function must determine the ordered list of methods
   applicable to the arguments.  Depending on the generic function and
   the arguments, this is done in one of three ways: using a memoized
   value; calling <a class="link" href="#compute-applicable-methods-UC" title="29.5.4.7. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES</code></a>; or calling
   <a class="link" href="#compute-applicable-methods" title="29.5.4.6. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS</code></a>.
   (Refer to the description of <a class="link" href="#compute-discriminating-function" title="29.5.4.11. Generic Function CLOS:COMPUTE-DISCRIMINATING-FUNCTION"><code class="function">CLOS:COMPUTE-DISCRIMINATING-FUNCTION</code></a> for
   the details of this process.)</p><p class="simpara">The following consistency relationship between
   <a class="link" href="#compute-applicable-methods-UC" title="29.5.4.7. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES</code></a> and <a class="link" href="#compute-applicable-methods" title="29.5.4.6. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS</code></a> must
   be maintained: for any given generic function and set of arguments,
   if <a class="link" href="#compute-applicable-methods-UC" title="29.5.4.7. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES</code></a> returns a second value of true,
   the <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#primary_value">primary value</a> must be equal to the value that would be returned by
   a corresponding call to <a class="link" href="#compute-applicable-methods" title="29.5.4.6. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS</code></a>.  The results
   are undefined if a portable method on either of these generic
   functions causes this consistency to be violated.</p><p class="simpara">The list returned by this function
 will not be mutated by the implementation.  The results are undefined
 if a portable program mutates the list returned by this function.</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#compute-applicable-methods-UC" title="29.5.4.7. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES</code></a>
   (<em class="replaceable"><code>generic-function</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>) <em class="replaceable"><code>classes</code></em>)</code></span></span></dt><dd><p class="simpara">If any method of the generic function has a
   specializer which is neither a <a class="link" href="#mop-class-mo">class metaobject</a> nor an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typspe_eql.html" target="_top"><code class="classname">EQL</code></a>
   specializer metaobject, this method <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>.</p><p class="simpara">In cases where the generic function has no methods with
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typspe_eql.html" target="_top"><code class="classname">EQL</code></a> specializers, or has no methods with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typspe_eql.html" target="_top"><code class="classname">EQL</code></a> specializers
   that could be applicable to arguments of the supplied classes, this
   method returns the ordered list of applicable methods as its first
   value and true as its second value.</p><p class="simpara">Otherwise this method returns an unspecified <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#primary_value">primary value</a> and
   false as its second value.</p><p class="simpara">This method can be overridden. Because of the consistency
   requirements between this generic function and
   <a class="link" href="#compute-applicable-methods" title="29.5.4.6. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS</code></a>, doing so may require also overriding
   <span class="method"><code class="literal"><a class="link" href="#compute-applicable-methods" title="29.5.4.6. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS</code></a>
    (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>) </code></span>.
</p></dd></dl></div><div class="simplesect"><div class="titlepage"><div><div><h5 class="title"><a id="mop-cam-UC-remarks"></a>Remarks</h5></div></div></div><p>This generic function exists to allow user extensions which alter
method lookup rules, but which base the new rules only on the classes of
the required arguments, to take advantage of the class-based method
lookup memoization found in many implementations.  (There is of course
no requirement for an implementation to provide this optimization.)</p><p>Such an extension can be implemented by two methods, one on this
generic function and one on <a class="link" href="#compute-applicable-methods" title="29.5.4.6. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS</code></a>.  Whenever
the user extension is in effect, the first method will return a second
value of true.  This should allow the implementation to absorb these
cases into its own memoization scheme.</p><p>To get appropriate performance, other kinds of extensions may
require methods on <a class="link" href="#compute-discriminating-function" title="29.5.4.11. Generic Function CLOS:COMPUTE-DISCRIMINATING-FUNCTION"><code class="function">CLOS:COMPUTE-DISCRIMINATING-FUNCTION</code></a> which implement
their own memoization scheme.</p></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="compute-effective-method"></a>29.5.4.8. Generic Function <a class="link" href="#compute-effective-method" title="29.5.4.8. Generic Function CLOS:COMPUTE-EFFECTIVE-METHOD"><code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#compute-effective-method" title="29.5.4.8. Generic Function CLOS:COMPUTE-EFFECTIVE-METHOD"><code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD</code></a> <em class="replaceable"><code>generic-function</code></em> <em class="replaceable"><code>method-combination</code></em>
    <em class="replaceable"><code>methods</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>generic-function</code></em></span></dt><dd>a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>method-combination</code></em></span></dt><dd>a <a class="link" href="#mop-meth-comp-mo">method combination metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>methods</code></em></span></dt><dd>a list of <a class="link" href="#mop-method-mo">method metaobject</a>s.</dd></dl></div></dd><dt><span class="term">Values</span></dt><dd><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">An effective method</li><li class="listitem">A list of effective method options
</li></ol></div></dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function is called to determine the
   effective method from a sorted list of <a class="link" href="#mop-method-mo">method metaobject</a>s.</p><p class="simpara">An effective method is a form that describes how the
    applicable methods are to be combined.  Inside of effective method
    forms are <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locmac_call-m__make-method.html" target="_top"><code class="function">CALL-METHOD</code></a> forms which indicate that a particular
    method is to be called.  The arguments to the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locmac_call-m__make-method.html" target="_top"><code class="function">CALL-METHOD</code></a> form
    indicate exactly how the method function of the method should be
    called.  (See <a class="link" href="#make-method-lambda" title="29.5.4.10. Generic Function CLOS:MAKE-METHOD-LAMBDA"><code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a> for more details about method
    functions.)</p><p class="simpara">An effective method option has the same interpretation and
    syntax as either the <code class="constant">:ARGUMENTS</code> or the <code class="constant">:GENERIC-FUNCTION</code> option in the long form
    of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-me_-combination.html" target="_top"><code class="function">DEFINE-METHOD-COMBINATION</code></a>.</p><p class="simpara">More information about the form and interpretation of
    effective methods and effective method options can be found under
    the description of the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-me_-combination.html" target="_top"><code class="function">DEFINE-METHOD-COMBINATION</code></a> macro in the
    <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> specification.</p><p class="simpara">This generic function can be called by the user or the
    implementation.  It is called by discriminating functions whenever a
    sorted list of applicable methods must be converted to an effective
    method.</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#compute-effective-method" title="29.5.4.8. Generic Function CLOS:COMPUTE-EFFECTIVE-METHOD"><code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD</code></a>
   (<em class="replaceable"><code>generic-function</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>) <em class="replaceable"><code>method-combination</code></em> <em class="replaceable"><code>methods</code></em>)</code></span></span></dt><dd><p class="simpara">This method computes the effective method according
   to the rules of the method combination type implemented by <em class="replaceable"><code>method-combination</code></em>.</p><p class="simpara">This method can be overridden.</p></dd></dl></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>The second return value may contain only one
  <code class="constant">:ARGUMENTS</code> option and only one <code class="constant">:GENERIC-FUNCTION</code> option. When overriding a
  <a class="link" href="#compute-effective-method" title="29.5.4.8. Generic Function CLOS:COMPUTE-EFFECTIVE-METHOD"><code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD</code></a> method, before adding an <code class="constant">:ARGUMENTS</code> or
  <code class="constant">:GENERIC-FUNCTION</code> option, you therefore need to check whether it this option is
  already present.</p></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="compute-effective-method-as-function"></a>29.5.4.9. Function <a class="link" href="#compute-effective-method-as-function" title="29.5.4.9. Function CLOS:COMPUTE-EFFECTIVE-METHOD-AS-FUNCTION"><code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD-AS-FUNCTION</code></a></h4></div></div></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p></p></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#compute-effective-method-as-function" title="29.5.4.9. Function CLOS:COMPUTE-EFFECTIVE-METHOD-AS-FUNCTION"><code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD-AS-FUNCTION</code></a>
    <em class="replaceable"><code>generic-function</code></em> <em class="replaceable"><code>methods</code></em> <em class="replaceable"><code>arguments</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>generic-function</code></em></span></dt><dd>a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>methods</code></em></span></dt><dd>a list of <a class="link" href="#mop-method-mo">method metaobject</a>s.</dd><dt><span class="term"><em class="replaceable"><code>arguments</code></em></span></dt><dd>a list of arguments.
   </dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>The effective method as a function, accepting any
   set of arguments for which all of the given methods are applicable.
</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This function is called to determine the effective method
   from a sorted list of <a class="link" href="#mop-method-mo">method metaobject</a>s, and convert it to a function.
   The <em class="replaceable"><code>arguments</code></em> are a set of arguments to which the methods are applicable,
   and are used solely for error message purposes.</p><p class="simpara">This function calls <a class="link" href="#compute-effective-method" title="29.5.4.8. Generic Function CLOS:COMPUTE-EFFECTIVE-METHOD"><code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD</code></a> using the <em class="replaceable"><code>generic-function</code></em>'s
   method combination, wraps local macro definitions for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locmac_call-m__make-method.html" target="_top"><code class="function">CALL-METHOD</code></a> and
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locmac_call-m__make-method.html" target="_top"><code class="function">MAKE-METHOD</code></a> around it, handles the <code class="constant">:ARGUMENTS</code> and <code class="constant">:GENERIC-FUNCTION</code> options,
   and compiles the resulting form to a function.</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="make-method-lambda"></a>29.5.4.10. Generic Function <a class="link" href="#make-method-lambda" title="29.5.4.10. Generic Function CLOS:MAKE-METHOD-LAMBDA"><code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#make-method-lambda" title="29.5.4.10. Generic Function CLOS:MAKE-METHOD-LAMBDA"><code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a> <em class="replaceable"><code>generic-function</code></em>
    <em class="replaceable"><code>method</code></em> <em class="replaceable"><code>lambda-expression</code></em> <em class="replaceable"><code><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-4.html">environment</a></code></em>)
 </code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>generic-function</code></em></span></dt><dd>a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>method</code></em></span></dt><dd>a (possibly uninitialized) <a class="link" href="#mop-method-mo">method metaobject</a>.
   </dd><dt><span class="term"><em class="replaceable"><code>lambda-expression</code></em></span></dt><dd>a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-3.html">lambda expression</a>.</dd><dt><span class="term"><em class="replaceable"><code><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-4.html">environment</a></code></em></span></dt><dd>the same as the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;ENVIRONMENT</code></a> argument to
     macro expansion functions.</dd></dl></div></dd><dt><span class="term">Values</span></dt><dd><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">A <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-3.html">lambda expression</a></li><li class="listitem">A list of initialization arguments and values
</li></ol></div></dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function is called to produce a
   <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-3.html">lambda expression</a> which can itself be used to produce a method function
   for a method and generic function with the specified classes.
   The generic function and method the method function will be used with
   are not required to be the given ones.
   Moreover, the <a class="link" href="#mop-method-mo">method metaobject</a> may be uninitialized.</p><p class="simpara">Either the function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile.html" target="_top"><code class="function">COMPILE</code></a>, the special form <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_function.html" target="_top"><code class="function">FUNCTION</code></a> or
   the function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_coerce.html" target="_top"><code class="function">COERCE</code></a> must be used to convert the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-3.html">lambda expression</a> a
   method function.  The method function itself can be applied to
   arguments with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_apply.html" target="_top"><code class="function">APPLY</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_funcall.html" target="_top"><code class="function">FUNCALL</code></a>.</p><p class="simpara">When a method is actually called by an effective method, its
   first argument will be a list of the arguments to the generic
   function.  Its remaining arguments will be all but the first argument
   passed to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locmac_call-m__make-method.html" target="_top"><code class="function">CALL-METHOD</code></a>.  By default, all method functions must
   accept two arguments: the list of arguments to the generic function
   and the list of next methods.</p><p class="simpara">For a given generic function and method class, the applicable
   methods on <a class="link" href="#make-method-lambda" title="29.5.4.10. Generic Function CLOS:MAKE-METHOD-LAMBDA"><code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a> and <a class="link" href="#compute-effective-method" title="29.5.4.8. Generic Function CLOS:COMPUTE-EFFECTIVE-METHOD"><code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD</code></a> must
   be consistent in the following way: each use of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locmac_call-m__make-method.html" target="_top"><code class="function">CALL-METHOD</code></a>
   returned by the method on <a class="link" href="#compute-effective-method" title="29.5.4.8. Generic Function CLOS:COMPUTE-EFFECTIVE-METHOD"><code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD</code></a> must have the
   same number of arguments, and the method lambda returned by the
   method on <a class="link" href="#make-method-lambda" title="29.5.4.10. Generic Function CLOS:MAKE-METHOD-LAMBDA"><code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a> must accept a corresponding number of
   arguments.</p><p class="simpara">Note that the system-supplied implementation of
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locfun_call-next-method.html" target="_top"><code class="function">CALL-NEXT-METHOD</code></a> is not required to handle extra arguments to the
   method function.  Users who define additional arguments to the method
   function must either redefine or forego <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locfun_call-next-method.html" target="_top"><code class="function">CALL-NEXT-METHOD</code></a>.  (See the
   example below.)</p><p class="simpara">When the <a class="link" href="#mop-method-mo">method metaobject</a> is created with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>, the method
   function must be the value of the <code class="constant">:FUNCTION</code> initialization
   argument.  The additional initialization arguments, returned as the
   second value of this generic function, must also be passed in this
   call to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>.</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#make-method-lambda" title="29.5.4.10. Generic Function CLOS:MAKE-METHOD-LAMBDA"><code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a>
   (<em class="replaceable"><code>generic-function</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>)
   (<em class="replaceable"><code>method</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-method.html" target="_top"><code class="classname">STANDARD-METHOD</code></a>) <em class="replaceable"><code>lambda-expression</code></em> <em class="replaceable"><code><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-4.html">environment</a></code></em>)</code></span></span></dt><dd><p class="simpara">This method returns a method lambda which accepts two
  arguments, the list of arguments to the generic function, and the list
  of next methods.  What initialization arguments may be returned in the
  second value are unspecified.</p><p class="simpara">This method can be overridden.</p></dd></dl></div><div class="informalexample"><a id="make-method-lambda-ex"></a><p>This example shows how to define a kind of method which, from
within the body of the method, has access to the actual <a class="link" href="#mop-method-mo">method metaobject</a> for the
method.  This simplified code overrides whatever method combination is
specified for the generic function, implementing a simple method
combination supporting only primary methods, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locfun_call-next-method.html" target="_top"><code class="function">CALL-NEXT-METHOD</code></a> and
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locfun_next-method-p.html" target="_top"><code class="function">NEXT-METHOD-P</code></a>.  (In addition, its a simplified version of
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locfun_call-next-method.html" target="_top"><code class="function">CALL-NEXT-METHOD</code></a> which does no error checking.)</p><p>Notice that the extra lexical function bindings get wrapped around
the body before <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locfun_call-next-method.html" target="_top"><code class="function">CALL-NEXT-METHOD</code></a> is called.  In this way, the user's
definition of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locfun_call-next-method.html" target="_top"><code class="function">CALL-NEXT-METHOD</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locfun_next-method-p.html" target="_top"><code class="function">NEXT-METHOD-P</code></a> are sure to
override the system's definitions.</p><pre class="programlisting">
(defclass my-generic-function (standard-generic-function)
  ()
  (:default-initargs :method-class (find-class 'my-method)))

(defclass my-method (standard-method) ())

(defmethod make-method-lambda ((gf my-generic-function)
                               (method my-method)
                               lambda-expression
                               environment)
  (declare (ignore environment))
  `(lambda (args next-methods this-method)
     (,(call-next-method gf method
         `(lambda ,(cadr lambda-expression)
            (flet ((this-method () this-method)
                   (call-next-method (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> cnm-args)
                     (funcall (method-function (car next-methods))
                              (or cnm-args args)
                              (cdr next-methods)
                              (car next-methods)))
                   (next-method-p ()
                     (not (null next-methods))))
              ,@(cddr lambda-expression)))
          environment)
       args next-methods)))

(defmethod compute-effective-method ((gf my-generic-function)
                                     method-combination
                                     methods)
  `(call-method ,(car methods) ,(cdr methods) ,(car methods)))
</pre></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p><a id="no-make-method-lambda"></a><strong>The generic function <a class="link" href="#make-method-lambda" title="29.5.4.10. Generic Function CLOS:MAKE-METHOD-LAMBDA"><code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a> is not implemented. </strong>Its specification is misdesigned: it mixes <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#compile_time">compile time</a> and
   <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#execution_time">execution time</a> behaviour. The essential problem is: where could the
   generic-function argument come from?
   </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">If a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a> form occurs in a source file, is
      <a class="link" href="#make-method-lambda" title="29.5.4.10. Generic Function CLOS:MAKE-METHOD-LAMBDA"><code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a> then called at compile time or at load time?
      If it was called at compile time, there's no possible value for
      the first argument, since the class of the generic function to
      which the method will belong is not known until load time.  If it
      was called at load time, it would mean that the method's source
      code could only be compiled at load time, not earlier - which
      defeats the purpose of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile-file.html" target="_top"><code class="function">COMPILE-FILE</code></a></li><li class="listitem">When a method is removed from a generic function
      using <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_remove-method.html" target="_top"><code class="function">REMOVE-METHOD</code></a> and then added through <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_add-method.html" target="_top"><code class="function">ADD-METHOD</code></a> to a
      different generic function, possibly belonging to a different
      generic function class, would <a class="link" href="#make-method-lambda" title="29.5.4.10. Generic Function CLOS:MAKE-METHOD-LAMBDA"><code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a> then be called
      again or not? If no, then <a class="link" href="#make-method-lambda" title="29.5.4.10. Generic Function CLOS:MAKE-METHOD-LAMBDA"><code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a>'s first argument is
      useless. If yes, then the source code of every method would have
      to be present at runtime, and its lexical environment as well.
 </li></ul></div><p><a id="method-functions-args"></a><strong>Method function arguments. </strong></p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locmac_call-m__make-method.html" target="_top"><code class="function">CALL-METHOD</code></a> always expect
      exactly two arguments: the method and a list of next methods.
    </li><li class="listitem">Method functions always
      expect exactly two arguments: the list of arguments passed to the
      generic function, and the list of next methods.
</li></ul></div></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="compute-discriminating-function"></a>29.5.4.11. Generic Function <a class="link" href="#compute-discriminating-function" title="29.5.4.11. Generic Function CLOS:COMPUTE-DISCRIMINATING-FUNCTION"><code class="function">CLOS:COMPUTE-DISCRIMINATING-FUNCTION</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#compute-discriminating-function" title="29.5.4.11. Generic Function CLOS:COMPUTE-DISCRIMINATING-FUNCTION"><code class="function">CLOS:COMPUTE-DISCRIMINATING-FUNCTION</code></a>
    <em class="replaceable"><code>generic-function</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>generic-function</code></em></span></dt><dd>a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>.</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>A function.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function is called to determine the
   discriminating function for a generic function.  When a generic
   function is called, the <strong class="first"><em class="firstterm">installed</em></strong>
   discriminating function is called with the full set of arguments
   received by the generic function, and must implement the behavior of
   calling the generic function: determining the ordered set of
   applicable methods, determining the effective method, and running the
   effective method.</p><p class="simpara">To determine the ordered set of applicable methods, the
   discriminating function first calls <a class="link" href="#compute-applicable-methods-UC" title="29.5.4.7. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES</code></a>.
   If <a class="link" href="#compute-applicable-methods-UC" title="29.5.4.7. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES</code></a> returns a second value of false,
   the discriminating function then calls <a class="link" href="#compute-applicable-methods" title="29.5.4.6. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS</code></a>.
  </p><p>When <a class="link" href="#compute-applicable-methods-UC" title="29.5.4.7. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES</code></a> returns a second
   value of true, the discriminating function is permitted to memoize
   the <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#primary_value">primary value</a> as follows.  The discriminating function may
   reuse the list of applicable methods without calling
   <a class="link" href="#compute-applicable-methods-UC" title="29.5.4.7. Generic Function CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES"><code class="function">CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES</code></a> again provided that:
   </p><div class="orderedlist"><ol class="orderedlist" type="i"><li class="listitem">the generic function is being called again with
      required arguments which are instances of the same classes,
    </li><li class="listitem">the generic function has not been reinitialized,
    </li><li class="listitem">no method has been added to or removed from the
      generic function,</li><li class="listitem">for all the specializers of all the generic
      function's methods which are classes, their class precedence lists
      have not changed, and</li><li class="listitem">for any such memoized value, the class precedence
      list of the class of each of the required arguments has not changed.
   </li></ol></div><p>
   Determination of the effective method is done by calling
   <a class="link" href="#compute-effective-method" title="29.5.4.8. Generic Function CLOS:COMPUTE-EFFECTIVE-METHOD"><code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD</code></a>.  When the effective method is run, each
   method's function is called, and receives as arguments:
   </p><div class="orderedlist"><ol class="orderedlist" type="i"><li class="listitem">a list of the arguments to the generic function,
    </li><li class="listitem">whatever other arguments are specified in the
      <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locmac_call-m__make-method.html" target="_top"><code class="function">CALL-METHOD</code></a> form indicating that the method should be called.
   </li></ol></div><p>
   (See <a class="link" href="#make-method-lambda" title="29.5.4.10. Generic Function CLOS:MAKE-METHOD-LAMBDA"><code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a> for more information about how method
   functions are called.)</p><p class="simpara">The generic function <a class="link" href="#compute-discriminating-function" title="29.5.4.11. Generic Function CLOS:COMPUTE-DISCRIMINATING-FUNCTION"><code class="function">CLOS:COMPUTE-DISCRIMINATING-FUNCTION</code></a> is
   called, and its result installed, by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_add-method.html" target="_top"><code class="function">ADD-METHOD</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_remove-method.html" target="_top"><code class="function">REMOVE-METHOD</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a>.
</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#compute-discriminating-function" title="29.5.4.11. Generic Function CLOS:COMPUTE-DISCRIMINATING-FUNCTION"><code class="function">CLOS:COMPUTE-DISCRIMINATING-FUNCTION</code></a>
    (<em class="replaceable"><code>generic-function</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>))</code></span></span></dt><dd><p class="simpara">No behavior is specified for this
   method beyond that which is specified for the generic function.</p><p class="simpara">This method can be overridden.</p></dd></dl></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>Overriding methods can make use of the function
  <a class="link" href="#compute-effective-method-as-function" title="29.5.4.9. Function CLOS:COMPUTE-EFFECTIVE-METHOD-AS-FUNCTION"><code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD-AS-FUNCTION</code></a>.  It is more convenient to call
  <a class="link" href="#compute-effective-method-as-function" title="29.5.4.9. Function CLOS:COMPUTE-EFFECTIVE-METHOD-AS-FUNCTION"><code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD-AS-FUNCTION</code></a> than <a class="link" href="#compute-effective-method" title="29.5.4.8. Generic Function CLOS:COMPUTE-EFFECTIVE-METHOD"><code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD</code></a>
  because the in the latter case one needs a lot of <span class="quote">“<span class="quote">glue
   code</span>”</span> for implementing the local macros <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locmac_call-m__make-method.html" target="_top"><code class="function">CALL-METHOD</code></a> and
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locmac_call-m__make-method.html" target="_top"><code class="function">MAKE-METHOD</code></a>, and this glue code is implementation dependent because
  it needs</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">to retrieve the declarations
     list stored in the method-combination object and</li><li class="listitem">to handle implementation dependent options that
     are returned as second value from <a class="link" href="#compute-effective-method" title="29.5.4.8. Generic Function CLOS:COMPUTE-EFFECTIVE-METHOD"><code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD</code></a>.
</li></ol></div></div></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="mop-meth"></a>29.6. Methods</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-meth-inheritance">29.6.1. Inheritance Structure of method metaobject Classes</a></span></dt><dt><span class="section"><a href="#mop-meth-mo-readers">29.6.2. Introspection: Readers for method metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#method-specializers">29.6.2.1. Generic Function <code class="function">CLOS:METHOD-SPECIALIZERS</code></a></span></dt><dt><span class="section"><a href="#method-qualifiers">29.6.2.2. Generic Function <code class="function">METHOD-QUALIFIERS</code></a></span></dt><dt><span class="section"><a href="#method-lambda-list">29.6.2.3. Generic Function <code class="function">CLOS:METHOD-LAMBDA-LIST</code></a></span></dt><dt><span class="section"><a href="#method-gf">29.6.2.4. Generic Function <code class="function">CLOS:METHOD-GENERIC-FUNCTION</code></a></span></dt><dt><span class="section"><a href="#method-function">29.6.2.5. Generic Function <code class="function">CLOS:METHOD-FUNCTION</code></a></span></dt><dt><span class="section"><a href="#mop-meth-mo-readers-methods">29.6.2.6. Methods</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-meth-init">29.6.3. Initialization of Methods</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-meth-init-defmethod">29.6.3.1. Macro <code class="function">DEFMETHOD</code></a></span></dt><dd><dl><dt><span class="section"><a href="#mop-meth-init-defmethod-body">29.6.3.1.1. Processing Method Bodies</a></span></dt><dt><span class="section"><a href="#mop-meth-init-defmethod-mo">29.6.3.1.2. Initialization of Generic Function and method metaobjects</a></span></dt><dt><span class="section"><a href="#mop-meth-efficiency">29.6.3.1.3. Efficiency</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-meth-init-mo">29.6.3.2. Initialization of method metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-meth-init-mo-method">29.6.3.2.1. Methods</a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="#mop-meth-customize">29.6.4. Customization</a></span></dt><dd><dl><dt><span class="section"><a href="#extract-lambda-list">29.6.4.1. Function <code class="function">CLOS:EXTRACT-LAMBDA-LIST</code></a></span></dt><dt><span class="section"><a href="#extract-specializer-names">29.6.4.2. Function <code class="function">CLOS:EXTRACT-SPECIALIZER-NAMES</code></a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-meth-inheritance"></a>29.6.1. Inheritance Structure of <a class="link" href="#mop-method-mo">method metaobject</a> Classes</h3></div></div></div><div class="figure"><a id="mop-meth-inheritance-fig"></a><p class="title"><strong>Figure 29.5. Inheritance structure of <a class="link" href="#mop-method-mo">method metaobject</a> classes</strong></p><div class="figure-contents"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="100%"><tr><td><img src="mop-classes-method.png" width="100%" alt="Inheritance structure of method metaobject classes" /></td></tr></table></div></div></div><br class="figure-break" /></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-meth-mo-readers"></a>29.6.2. Introspection: Readers for <a class="link" href="#mop-method-mo">method metaobject</a>s</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#method-specializers">29.6.2.1. Generic Function <code class="function">CLOS:METHOD-SPECIALIZERS</code></a></span></dt><dt><span class="section"><a href="#method-qualifiers">29.6.2.2. Generic Function <code class="function">METHOD-QUALIFIERS</code></a></span></dt><dt><span class="section"><a href="#method-lambda-list">29.6.2.3. Generic Function <code class="function">CLOS:METHOD-LAMBDA-LIST</code></a></span></dt><dt><span class="section"><a href="#method-gf">29.6.2.4. Generic Function <code class="function">CLOS:METHOD-GENERIC-FUNCTION</code></a></span></dt><dt><span class="section"><a href="#method-function">29.6.2.5. Generic Function <code class="function">CLOS:METHOD-FUNCTION</code></a></span></dt><dt><span class="section"><a href="#mop-meth-mo-readers-methods">29.6.2.6. Methods</a></span></dt></dl></div><p>The reader generic functions which simply return information
associated with <a class="link" href="#mop-method-mo">method metaobject</a>s are presented together here in the
format described in <a class="xref" href="#mop-cl-readers" title="29.3.3. Introspection: Readers for class metaobjects">Section 29.3.3, “Introspection: Readers for class metaobjects”</a>.</p><p>Each of these reader generic functions have the same syntax,
accepting one required argument called <em class="replaceable"><code>method</code></em>, which must be a
<a class="link" href="#mop-method-mo">method metaobject</a>; otherwise, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.  An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is also <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed
if the <a class="link" href="#mop-method-mo">method metaobject</a> has not been initialized.</p><p>These
  generic functions can be called by the user or the implementation.</p><p>For any of these generic functions which returns a list, such lists
  will not be mutated by the implementation.  The results are undefined if a
  portable program allows such a list to be mutated.</p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="method-specializers"></a>29.6.2.1. Generic Function <a class="link" href="#method-specializers" title="29.6.2.1. Generic Function CLOS:METHOD-SPECIALIZERS"><code class="function">CLOS:METHOD-SPECIALIZERS</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#method-specializers" title="29.6.2.1. Generic Function CLOS:METHOD-SPECIALIZERS"><code class="function">CLOS:METHOD-SPECIALIZERS</code></a> <em class="replaceable"><code>method</code></em>)</code></h5></div></div></div><p>Returns a list of the specializers of <em class="replaceable"><code>method</code></em>.  This value is a
list of specializer metaobjects.  This is the value of the
<code class="constant">:SPECIALIZERS</code> initialization argument that was associated with the
method during initialization.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="method-qualifiers"></a>29.6.2.2. Generic Function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_met_d-qualifiers.html" target="_top"><code class="function">METHOD-QUALIFIERS</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_met_d-qualifiers.html" target="_top"><code class="function">METHOD-QUALIFIERS</code></a> <em class="replaceable"><code>method</code></em>)</code></h5></div></div></div><p>Returns a (possibly empty) list of the qualifiers of <em class="replaceable"><code>method</code></em>.
This value is a list of non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> atoms.  This is the defaulted value of
the <code class="constant">:QUALIFIERS</code> initialization argument that was associated with the
method during initialization.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="method-lambda-list"></a>29.6.2.3. Generic Function <a class="link" href="#method-lambda-list" title="29.6.2.3. Generic Function CLOS:METHOD-LAMBDA-LIST"><code class="function">CLOS:METHOD-LAMBDA-LIST</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#method-lambda-list" title="29.6.2.3. Generic Function CLOS:METHOD-LAMBDA-LIST"><code class="function">CLOS:METHOD-LAMBDA-LIST</code></a> <em class="replaceable"><code>method</code></em>)</code></h5></div></div></div><p>Returns the (unspecialized) <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> of <em class="replaceable"><code>method</code></em>.  This value
is a <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a>.  This is the value of the <code class="constant">:LAMBDA-LIST</code>
initialization argument that was associated with the method during
initialization.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="method-gf"></a>29.6.2.4. Generic Function <a class="link" href="#method-gf" title="29.6.2.4. Generic Function CLOS:METHOD-GENERIC-FUNCTION"><code class="function">CLOS:METHOD-GENERIC-FUNCTION</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#method-gf" title="29.6.2.4. Generic Function CLOS:METHOD-GENERIC-FUNCTION"><code class="function">CLOS:METHOD-GENERIC-FUNCTION</code></a> <em class="replaceable"><code>method</code></em>)</code></h5></div></div></div><p>Returns the generic function that <em class="replaceable"><code>method</code></em> is currently
connected to, or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if it is not currently connected to any generic
function.  This value is either a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
When a method is first created it is not connected to any generic
function.  This connection is maintained by the generic functions
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_add-method.html" target="_top"><code class="function">ADD-METHOD</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_remove-method.html" target="_top"><code class="function">REMOVE-METHOD</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="method-function"></a>29.6.2.5. Generic Function <a class="link" href="#method-function" title="29.6.2.5. Generic Function CLOS:METHOD-FUNCTION"><code class="function">CLOS:METHOD-FUNCTION</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#method-function" title="29.6.2.5. Generic Function CLOS:METHOD-FUNCTION"><code class="function">CLOS:METHOD-FUNCTION</code></a> <em class="replaceable"><code>method</code></em>)</code></h5></div></div></div><p>Returns the method function of <em class="replaceable"><code>method</code></em>.  This is the
value of the <code class="constant">:FUNCTION</code> initialization argument that was associated
with the method during initialization.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-meth-mo-readers-methods"></a>29.6.2.6. Methods</h4></div></div></div><div class="variablelist"><p class="title"><strong>The specified methods for the <a class="link" href="#mop-method-mo">method metaobject</a> readers</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#method-specializers" title="29.6.2.1. Generic Function CLOS:METHOD-SPECIALIZERS"><code class="function">CLOS:METHOD-SPECIALIZERS</code></a>
   (<em class="replaceable"><code>method</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-method.html" target="_top"><code class="classname">STANDARD-METHOD</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_met_d-qualifiers.html" target="_top"><code class="function">METHOD-QUALIFIERS</code></a>
   (<em class="replaceable"><code>method</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-method.html" target="_top"><code class="classname">STANDARD-METHOD</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#method-lambda-list" title="29.6.2.3. Generic Function CLOS:METHOD-LAMBDA-LIST"><code class="function">CLOS:METHOD-LAMBDA-LIST</code></a>
   (<em class="replaceable"><code>method</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-method.html" target="_top"><code class="classname">STANDARD-METHOD</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#method-function" title="29.6.2.5. Generic Function CLOS:METHOD-FUNCTION"><code class="function">CLOS:METHOD-FUNCTION</code></a>
   (<em class="replaceable"><code>method</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-method.html" target="_top"><code class="classname">STANDARD-METHOD</code></a>))</code></span></span></dt><dd>No behavior is specified for these
   methods beyond that which is specified for their respective generic
   functions.</dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#method-gf" title="29.6.2.4. Generic Function CLOS:METHOD-GENERIC-FUNCTION"><code class="function">CLOS:METHOD-GENERIC-FUNCTION</code></a>
   (<em class="replaceable"><code>method</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-method.html" target="_top"><code class="classname">STANDARD-METHOD</code></a>))</code></span></span></dt><dd><p class="simpara">No behavior is specified for this
   method beyond that which is specified for the generic function.</p><p class="simpara">The value returned by this method is maintained by
  <span class="method"><code class="literal"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_add-method.html" target="_top"><code class="function">ADD-METHOD</code></a>(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-method.html" target="_top"><code class="classname">STANDARD-METHOD</code></a>)</code></span> and
  <span class="method"><code class="literal"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_remove-method.html" target="_top"><code class="function">REMOVE-METHOD</code></a>(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-method.html" target="_top"><code class="classname">STANDARD-METHOD</code></a>)</code></span>.</p></dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-meth-init"></a>29.6.3. Initialization of Methods</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-meth-init-defmethod">29.6.3.1. Macro <code class="function">DEFMETHOD</code></a></span></dt><dd><dl><dt><span class="section"><a href="#mop-meth-init-defmethod-body">29.6.3.1.1. Processing Method Bodies</a></span></dt><dt><span class="section"><a href="#mop-meth-init-defmethod-mo">29.6.3.1.2. Initialization of Generic Function and method metaobjects</a></span></dt><dt><span class="section"><a href="#mop-meth-efficiency">29.6.3.1.3. Efficiency</a></span></dt></dl></dd><dt><span class="section"><a href="#mop-meth-init-mo">29.6.3.2. Initialization of method metaobjects</a></span></dt><dd><dl><dt><span class="section"><a href="#mop-meth-init-mo-method">29.6.3.2.1. Methods</a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-meth-init-defmethod"></a>29.6.3.1. Macro <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a></h4></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-meth-init-defmethod-body">29.6.3.1.1. Processing Method Bodies</a></span></dt><dt><span class="section"><a href="#mop-meth-init-defmethod-mo">29.6.3.1.2. Initialization of Generic Function and method metaobjects</a></span></dt><dt><span class="section"><a href="#mop-meth-efficiency">29.6.3.1.3. Efficiency</a></span></dt></dl></div><p>The evaluation or execution of a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a> form requires first
that the body of the method be converted to a method function.
This process is described
<a class="link" href="#mop-meth-init-defmethod-body" title="29.6.3.1.1. Processing Method Bodies">below</a>.
The result of this process is a method function and a set of additional
initialization arguments to be used when creating the new method.
Given these two values, the evaluation or execution of a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a>
form proceeds in three steps.</p><p>The first step ensures the existence of a generic function with
the specified name.  This is done by calling the function <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a>.
The first argument in this call is the generic function name specified
in the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a> form.</p><p>The second step is the creation of the new <a class="link" href="#mop-method-mo">method metaobject</a> by calling
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>.  The class of the new <a class="link" href="#mop-method-mo">method metaobject</a> is determined by calling
<a class="link" href="#gf-method-class" title="29.5.2.6. Generic Function CLOS:GENERIC-FUNCTION-METHOD-CLASS"><code class="function">CLOS:GENERIC-FUNCTION-METHOD-CLASS</code></a> on the result of the call to <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a> from the
first step.</p><p>The initialization arguments received by the call to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>
are as follows:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The value of the <code class="constant">:QUALIFIERS</code> initialization
argument is a list of the qualifiers which appeared in the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a>
form.  No special processing is done on these values.  The order of the
elements of this list is the same as in the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a> form.
</li><li class="listitem">The value of the <code class="constant">:LAMBDA-LIST</code> initialization
argument is the unspecialized <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> from the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a> form.
</li><li class="listitem">The value of the <code class="constant">:SPECIALIZERS</code> initialization
argument is a list of the specializers for the method.  For specializers
which are classes, the specializer is the <a class="link" href="#mop-class-mo">class metaobject</a> itself.  In
the case of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typspe_eql.html" target="_top"><code class="classname">EQL</code></a> specializers, it will be an <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:EQL-SPECIALIZER</code></a>
metaobject obtained by calling <a class="link" href="#intern-eql-specializer" title="29.8.3.1. Function CLOS:INTERN-EQL-SPECIALIZER"><code class="function">CLOS:INTERN-EQL-SPECIALIZER</code></a> on the result of
evaluating the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typspe_eql.html" target="_top"><code class="classname">EQL</code></a> specializer form in the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a> of the
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a> form.</li><li class="listitem">The value of the <code class="constant">:FUNCTION</code> initialization
argument is the method function.</li><li class="listitem"><p class="simpara">The value of the <code class="constant">:DECLARATIONS</code> initialization
argument is a list of the <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_d.html#declaration_specifier">declaration specifier</a>s from the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a> form.
If there are no declarations in the macro form, this initialization argument
either does not appear, or appears with a value of the empty list.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>No <code class="constant">:DECLARATIONS</code> initialization argument is
  provided, because method initialization does not support a <code class="constant">:DECLARATIONS</code>
  argument, and because the method function is already completely provided
  through the <code class="constant">:FUNCTION</code> initialization argument.</p></div></li><li class="listitem">The value of the <code class="constant">:DOCUMENTATION</code> initialization
argument is the documentation string from the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a> form.  If
there is no documentation string in the macro form this initialization
argument either does not appear, or appears with a value of false.
</li><li class="listitem">Any other initialization argument produced in
conjunction with the method function are also included.</li><li class="listitem">The implementation is free to include additional
initialization arguments provided these are not symbols accessible in
the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-2.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP-USER</span>”</span></strong></a> package, or exported by any package defined in the
[<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>].</li></ul></div><p>In the third step, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_add-method.html" target="_top"><code class="function">ADD-METHOD</code></a> is called to add the newly created
method to the set of methods associated with the <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>.</p><p>The result of the call to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_add-method.html" target="_top"><code class="function">ADD-METHOD</code></a> is returned as the result
of evaluating or executing the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a> form.</p><p>An example showing a typical <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a> form and a sample
expansion is shown in the following example:
</p><div class="informalexample"><a id="defmethod-ex-1"></a><p>An example <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a> form and one possible correct
  expansion. In the expansion, <em class="replaceable"><code>method-lambda</code></em>
  is the result of calling <a class="link" href="#make-method-lambda" title="29.5.4.10. Generic Function CLOS:MAKE-METHOD-LAMBDA"><code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a> as described in
  <a class="xref" href="#mop-meth-init-defmethod-body" title="29.6.3.1.1. Processing Method Bodies">Section 29.6.3.1.1, “Processing Method Bodies”</a>.
  The initargs appearing after <code class="constant">:FUNCTION</code> are assumed to be additional
  initargs returned from the call to <a class="link" href="#make-method-lambda" title="29.5.4.10. Generic Function CLOS:MAKE-METHOD-LAMBDA"><code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a>.</p><pre class="programlisting">
(defmethod move :before ((p position) (l (eql 0))
                         <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> (visiblyp t)
                         <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> color)
  (set-to-origin p)
  (when visiblyp (show-move p 0 color)))

(let ((#:g001 (ensure-generic-function 'move)))
  (add-method #:g001
    (make-instance (generic-function-method-class #:g001)
                   :qualifiers '(:before)
                   :specializers (list (find-class 'position)
                                       (intern-eql-specializer 0))
                   :lambda-list '(p l <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> (visiblyp t)
                                      <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> color)
                   :function (function <em class="replaceable"><code>method-lambda</code></em>)
                   'additional-initarg-1 't
                   'additional-initarg-2 '39)))
</pre></div><p>The processing of the method body for this method is shown
 <a class="link" href="#defmethod-ex-2">below</a>.</p><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="mop-meth-init-defmethod-body"></a>29.6.3.1.1. Processing Method Bodies</h5></div></div></div><p>Before a method can be created, the list of forms comprising the
method body must be converted to a method function.  This conversion is
a two step process.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>The body of methods can also appear in the
<code class="constant">:METHOD</code> option of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a> forms.  Initial methods are
not considered by any of the protocols specified in this document.
</p></div><div class="informalexample"><a id="defmethod-ex-2"></a><p>During macro-expansion of the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a> macro shown in
  the <a class="link" href="#defmethod-ex-1">previous example</a> code
  similar to this would be run to produce the method lambda and
  additional initargs.  In this example, <em class="replaceable"><code><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-4.html">environment</a></code></em> is the macroexpansion
  environment of the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a> macro form.</p><pre class="programlisting">
(let ((gf (ensure-generic-function 'move)))
  (make-method-lambda
    gf
    (class-prototype (generic-function-method-class gf))
    '(lambda (p l <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> (visiblyp t) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> color)
       (set-to-origin p)
       (when visiblyp (show-move p 0 color)))
    <em class="replaceable"><code><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-4.html">environment</a></code></em>))
</pre></div><p>The first step occurs during macro-expansion of the macro form.
In this step, the method <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a>, declarations and body are
converted to a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-3.html">lambda expression</a> called a <strong class="first"><em class="firstterm">method lambda
  <a id="method-lambda" class="indexterm"></a></em></strong>.
This conversion is based on information associated with the generic
function definition in effect at the time the macro form is expanded.</p><p>The generic function definition is obtained by calling <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a> with
 a first argument of the generic function name specified in the macro form.
The <code class="constant">:LAMBDA-LIST</code> keyword argument is not passed in this call.</p><p>Given the generic function, production of the method lambda
proceeds by calling <a class="link" href="#make-method-lambda" title="29.5.4.10. Generic Function CLOS:MAKE-METHOD-LAMBDA"><code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a>.
The first argument in this call is the generic function obtained as
described above.
The second argument is the result of calling <a class="link" href="#class-prototype" title="29.3.3.10. Generic Function CLOS:CLASS-PROTOTYPE"><code class="function">CLOS:CLASS-PROTOTYPE</code></a> on the
result of calling <a class="link" href="#gf-method-class" title="29.5.2.6. Generic Function CLOS:GENERIC-FUNCTION-METHOD-CLASS"><code class="function">CLOS:GENERIC-FUNCTION-METHOD-CLASS</code></a> on the generic function.
The third argument is a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-3.html">lambda expression</a> formed from the method <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a>,
declarations and body.
The fourth argument is the macro-expansion environment of the macro
form; this is the value of the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;ENVIRONMENT</code></a> argument to the
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a> macro.</p><p>The generic function <a class="link" href="#make-method-lambda" title="29.5.4.10. Generic Function CLOS:MAKE-METHOD-LAMBDA"><code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a> returns two values.
The first is the method lambda itself.
The second is a list of initialization arguments and values.  These are
included in the initialization arguments when the method is created.</p><p>In the second step, the method lambda is converted to a function
which properly captures the lexical scope of the macro form.  This is
done by having the method lambda appear in the macro-expansion as the
argument of the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_function.html" target="_top"><code class="function">FUNCTION</code></a> special form.  During the subsequent
evaluation of the macro-expansion, the result of the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_function.html" target="_top"><code class="function">FUNCTION</code></a> special
form is the method function.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>See <a class="xref" href="#no-make-method-lambda" title="The generic function CLOS:MAKE-METHOD-LAMBDA is not implemented">The generic function <code class="function">CLOS:MAKE-METHOD-LAMBDA</code> is not implemented</a>.
</p></div></div><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="mop-meth-init-defmethod-mo"></a>29.6.3.1.2. Initialization of Generic Function and <a class="link" href="#mop-method-mo">method metaobject</a>s</h5></div></div></div><p>An example of creating a generic function and a <a class="link" href="#mop-method-mo">method metaobject</a>, and then
adding the method to the generic function is shown below.  This example
is comparable to the method definition shown
 <a class="link" href="#defmethod-ex-1">above</a>:
</p><pre class="programlisting">
(let* ((gf (make-instance 'standard-generic-function
                          :lambda-list '(p l <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> visiblyp <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>)))
       (method-class (generic-function-method-class gf)))
  (multiple-value-bind (lambda initargs)
       (make-method-lambda
         gf
         (class-prototype method-class)
         '(lambda (p l <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> (visiblyp t) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> color)
            (set-to-origin p)
            (when visiblyp (show-move p 0 color)))
         nil)
    (add-method gf
                (apply #'make-instance method-class
                       :function (compile nil lambda)
                       :specializers (list (find-class 'position)
                                           (intern-eql-specializer 0))
                       :qualifiers ()
                       :lambda-list '(p l <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> (visiblyp t)
                                          <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> color)
                       initargs))))
</pre></div><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="mop-meth-efficiency"></a>29.6.3.1.3. Efficiency</h5></div><div><h6 class="subtitle">Implementation dependent: only in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> and some other
  implementations</h6></div></div></div><p>Methods created through <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a> have a faster calling
  convention than methods created through a portable <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>
  invocation.</p></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-meth-init-mo"></a>29.6.3.2. Initialization of <a class="link" href="#mop-method-mo">method metaobject</a>s</h4></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-meth-init-mo-method">29.6.3.2.1. Methods</a></span></dt></dl></div><p>A <a class="link" href="#mop-method-mo">method metaobject</a> can be created by calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>.
The initialization arguments establish the definition of the method.
A <a class="link" href="#mop-method-mo">method metaobject</a> cannot be redefined;
calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>.</p><p>Initialization of a <a class="link" href="#mop-method-mo">method metaobject</a> must be done by calling <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>
and allowing it to call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a>.  Portable programs must
<span class="strong"><strong>not</strong></span></p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">... call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a> directly to
    initialize a <a class="link" href="#mop-method-mo">method metaobject</a>;</li><li class="listitem">... call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_sha_d-initialize.html" target="_top"><code class="function">SHARED-INITIALIZE</code></a> directly to
    initialize a <a class="link" href="#mop-method-mo">method metaobject</a>;</li><li class="listitem">... call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_change-class.html" target="_top"><code class="function">CHANGE-CLASS</code></a> to change the class of any
    <a class="link" href="#mop-method-mo">method metaobject</a> or to turn a non-method object into a <a class="link" href="#mop-method-mo">method metaobject</a>.
</li></ul></div><p>Since metaobject classes may not be redefined,
 no behavior is specified for the result of calls to
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_upd_efined-class.html" target="_top"><code class="function">UPDATE-INSTANCE-FOR-REDEFINED-CLASS</code></a> on <a class="link" href="#mop-method-mo">method metaobject</a>s.
 Since the class of a <a class="link" href="#mop-method-mo">method metaobject</a> cannot be changed,
 no behavior is specified for the result of calls to
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_upd_ferent-class.html" target="_top"><code class="function">UPDATE-INSTANCE-FOR-DIFFERENT-CLASS</code></a> on <a class="link" href="#mop-method-mo">method metaobject</a>s.</p><p>During initialization, each initialization argument is checked
for errors and then associated with the <a class="link" href="#mop-method-mo">method metaobject</a>.  The value
can then be accessed by calling the appropriate accessor as shown in
<a class="xref" href="#mop-meth-initargs" title="Table 29.5. Initialization arguments and accessors for method metaobjects">Table 29.5, “Initialization arguments and   accessors for method metaobjects”</a>.</p><p>This section begins with a description of the error checking and
processing of each initialization argument.  This is followed by a table
showing the generic functions that can be used to access the stored
initialization arguments.  The section ends with a set of restrictions
on portable methods affecting <a class="link" href="#mop-method-mo">method metaobject</a> initialization.</p><p>In these descriptions, the phrase <span class="quote">“<span class="quote">this argument defaults to
<em class="replaceable"><code>value</code></em></span>”</span> means that when that initialization argument is not
supplied, initialization is performed as if <em class="replaceable"><code>value</code></em> had been supplied.
For some initialization arguments this could be done by the use of
default initialization arguments, but whether it is done this way is not
specified.  Implementations are free to define default initialization
arguments for specified <a class="link" href="#mop-method-mo">method metaobject</a> classes.  Portable programs
are free to define default initialization arguments for portable
subclasses of the class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a>.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The <code class="constant">:QUALIFIERS</code> argument is a list of method
   qualifiers.  An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if this value is not a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#proper_list">proper list</a>, or if
   any element of the list is not a non-null atom. This argument
   defaults to the empty list.</li><li class="listitem">The <code class="constant">:LAMBDA-LIST</code> argument is the unspecialized
   <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> of the method.  An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if this value is not a
   proper <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a>. If this value is not supplied, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.
 </li><li class="listitem">The <code class="constant">:SPECIALIZERS</code> argument is a list of the
   specializer metaobjects for the method.  An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if this value
   is not a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#proper_list">proper list</a>, or if the length of the list differs from the
   number of required arguments in the <code class="constant">:LAMBDA-LIST</code> argument, or if
   any element of the list is not a specializer metaobject.  If this
   value is not supplied, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.</li><li class="listitem"> The <code class="constant">:FUNCTION</code> argument is a method function.  It
   must be compatible with the methods on <a class="link" href="#compute-effective-method" title="29.5.4.8. Generic Function CLOS:COMPUTE-EFFECTIVE-METHOD"><code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD</code></a>
   defined for this class of method and generic function with which it
   will be used.  That is, it must accept the same number of arguments
   as all uses of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locmac_call-m__make-method.html" target="_top"><code class="function">CALL-METHOD</code></a> that will call it supply.  (See
   <a class="link" href="#compute-effective-method" title="29.5.4.8. Generic Function CLOS:COMPUTE-EFFECTIVE-METHOD"><code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD</code></a> and <a class="link" href="#make-method-lambda" title="29.5.4.10. Generic Function CLOS:MAKE-METHOD-LAMBDA"><code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a> for more information.)
   An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if this argument is not supplied.</li><li class="listitem"> When the method being initialized is an instance of
   a subclass of <a class="link" href="#mop-meth-init-mo" title="29.6.3.2. Initialization of method metaobjects"><code class="classname">CLOS:STANDARD-ACCESSOR-METHOD</code></a>, the <code class="constant">:SLOT-DEFINITION</code>
   initialization argument must be provided.  Its value is the direct
   <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> which defines this accessor method.  An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if the value
   is not an instance of a subclass of <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:DIRECT-SLOT-DEFINITION</code></a>.</li><li class="listitem">The <code class="constant">:DOCUMENTATION</code> argument is a string or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
   An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed if this value is not a string or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.  This argument
   defaults to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</li></ul></div><p>After the processing and defaulting of initialization arguments
described above, the value of each initialization argument is associated
with the <a class="link" href="#mop-method-mo">method metaobject</a>.  These values can then be accessed by calling the
corresponding generic function.  The correspondences are as follows:

</p><div class="table"><a id="mop-meth-initargs"></a><p class="title"><strong>Table 29.5. Initialization arguments and
  accessors for <a class="link" href="#mop-method-mo">method metaobject</a>s</strong></p><div class="table-contents"><table class="table" summary="Initialization arguments and&#10;  accessors for method metaobjects" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="center">Initialization Argument</th><th align="center">Generic Function</th></tr></thead><tbody><tr><td align="center"><code class="constant">:QUALIFIERS</code></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_met_d-qualifiers.html" target="_top"><code class="function">METHOD-QUALIFIERS</code></a></td></tr><tr><td align="center"><code class="constant">:LAMBDA-LIST</code></td><td align="center"><a class="link" href="#method-lambda-list" title="29.6.2.3. Generic Function CLOS:METHOD-LAMBDA-LIST"><code class="function">CLOS:METHOD-LAMBDA-LIST</code></a></td></tr><tr><td align="center"><code class="constant">:SPECIALIZERS</code></td><td align="center"><a class="link" href="#method-specializers" title="29.6.2.1. Generic Function CLOS:METHOD-SPECIALIZERS"><code class="function">CLOS:METHOD-SPECIALIZERS</code></a></td></tr><tr><td align="center"><code class="constant">:FUNCTION</code></td><td align="center"><a class="link" href="#method-function" title="29.6.2.5. Generic Function CLOS:METHOD-FUNCTION"><code class="function">CLOS:METHOD-FUNCTION</code></a></td></tr><tr><td align="center"><code class="constant">:SLOT-DEFINITION</code></td><td align="center"><a class="link" href="#accessor-method-slotdef" title="29.7.1.1. Generic Function CLOS:ACCESSOR-METHOD-SLOT-DEFINITION"><code class="function">CLOS:ACCESSOR-METHOD-SLOT-DEFINITION</code></a></td></tr><tr><td align="center"><code class="constant">:DOCUMENTATION</code></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_doc_umentationcp.html" target="_top"><code class="function">DOCUMENTATION</code></a></td></tr></tbody></table></div></div><p><br class="table-break" /></p><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="mop-meth-init-mo-method"></a>29.6.3.2.1. Methods</h5></div></div></div><p>It is not specified which methods provide the initialization
behavior described above.  Instead, the information needed to allow
portable programs to specialize this behavior is presented in as a set
of restrictions on the methods a portable program can define.  The model
is that portable initialization methods have access to the <a class="link" href="#mop-method-mo">method metaobject</a> when
either all or none of the specified initialization has taken
effect.</p><p>These restrictions govern the methods that a portable program can
define on the generic functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a>,
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a>, and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_sha_d-initialize.html" target="_top"><code class="function">SHARED-INITIALIZE</code></a>.  These restrictions
apply only to methods on these generic functions for which the first
specializer is a subclass of the class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a>.  Other portable
methods on these generic functions are not affected by these
restrictions.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Portable programs must not define methods on
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_sha_d-initialize.html" target="_top"><code class="function">SHARED-INITIALIZE</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a>.</li><li class="listitem"><p>For <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a>:
   </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; "><li class="listitem">Portable programs must not define primary methods.
 </li><li class="listitem">Portable programs may define around-methods, but
   these must be extending, not overriding methods.</li><li class="listitem">Portable before-methods must assume that when they
   are run, none of the initialization behavior described above has been
   completed.</li><li class="listitem">Portable after-methods must assume that when they
   are run, all of the initialization behavior described above has been
   completed.</li></ul></div></li></ul></div><p>The results are undefined if any of
 these restrictions are violated.</p></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-meth-customize"></a>29.6.4. Customization</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#extract-lambda-list">29.6.4.1. Function <code class="function">CLOS:EXTRACT-LAMBDA-LIST</code></a></span></dt><dt><span class="section"><a href="#extract-specializer-names">29.6.4.2. Function <code class="function">CLOS:EXTRACT-SPECIALIZER-NAMES</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="extract-lambda-list"></a>29.6.4.1. Function <a class="link" href="#extract-lambda-list" title="29.6.4.1. Function CLOS:EXTRACT-LAMBDA-LIST"><code class="function">CLOS:EXTRACT-LAMBDA-LIST</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#extract-lambda-list" title="29.6.4.1. Function CLOS:EXTRACT-LAMBDA-LIST"><code class="function">CLOS:EXTRACT-LAMBDA-LIST</code></a> <em class="replaceable"><code>specialized-lambda-list</code></em>)
</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>specialized-lambda-list</code></em></span></dt><dd>a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-3.html">specialized lambda list</a> as accepted by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a>.
</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>An unspecialized <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a>.
</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This function takes a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-3.html">specialized lambda list</a> and
   returns the <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> with the specializers removed.  This is a
   non-destructive operation.  Whether the result shares any structure
   with the argument is unspecified.</p><p class="simpara">If the <em class="replaceable"><code>specialized-lambda-list</code></em> argument does not have legal syntax,
   an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.  This syntax checking does not check the syntax of the
   actual specializer names, only the syntax of the <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> and
   where the specializers appear.
</p></dd></dl></div><div class="informalexample"><a id="extract-lambda-list-ex"></a><pre class="programlisting">
(<a class="link" href="#extract-lambda-list" title="29.6.4.1. Function CLOS:EXTRACT-LAMBDA-LIST"><code class="function">CLOS:EXTRACT-LAMBDA-LIST</code></a> '((p position)))
⇒ <code class="computeroutput">(P)</code>
(<a class="link" href="#extract-lambda-list" title="29.6.4.1. Function CLOS:EXTRACT-LAMBDA-LIST"><code class="function">CLOS:EXTRACT-LAMBDA-LIST</code></a> '((p position) x y))
⇒ <code class="computeroutput">(P X Y)</code>
(<a class="link" href="#extract-lambda-list" title="29.6.4.1. Function CLOS:EXTRACT-LAMBDA-LIST"><code class="function">CLOS:EXTRACT-LAMBDA-LIST</code></a> '(a (b (eql x)) c <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> i))
⇒ <code class="computeroutput">(A B C <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> I)</code>
</pre></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="extract-specializer-names"></a>29.6.4.2. Function <a class="link" href="#extract-specializer-names" title="29.6.4.2. Function CLOS:EXTRACT-SPECIALIZER-NAMES"><code class="function">CLOS:EXTRACT-SPECIALIZER-NAMES</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#extract-specializer-names" title="29.6.4.2. Function CLOS:EXTRACT-SPECIALIZER-NAMES"><code class="function">CLOS:EXTRACT-SPECIALIZER-NAMES</code></a>
    <em class="replaceable"><code>specialized-lambda-list</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>specialized-lambda-list</code></em></span></dt><dd>a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-3.html">specialized lambda list</a> as accepted by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a>.
</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>A list of specializer names.
</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This function takes a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-3.html">specialized lambda list</a> and
   returns its specializer names.  This is a non-destructive operation.
   Whether the result shares structure with the argument is unspecified.
  </p><p class="simpara">The list returned by this function
 will not be mutated by the implementation.  The results are undefined
 if a portable program mutates the list returned by this function.</p><p class="simpara">The result of this function will be a list with a
   number of elements equal to the number of required arguments in
   <em class="replaceable"><code>specialized-lambda-list</code></em>.  Specializers are defaulted to the symbol <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>.
  </p><p class="simpara">If the <em class="replaceable"><code>specialized-lambda-list</code></em> argument does not have legal
   syntax, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.  This syntax checking does not check the syntax
   of the actual specializer names, only the syntax of the <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a>
   and where the specializers appear.
</p></dd></dl></div><div class="informalexample"><a id="extract-specializer-names-ex"></a><pre class="programlisting">
(<a class="link" href="#extract-specializer-names" title="29.6.4.2. Function CLOS:EXTRACT-SPECIALIZER-NAMES"><code class="function">CLOS:EXTRACT-SPECIALIZER-NAMES</code></a> '((p position)))
⇒ <code class="computeroutput">(POSITION)</code>
(<a class="link" href="#extract-specializer-names" title="29.6.4.2. Function CLOS:EXTRACT-SPECIALIZER-NAMES"><code class="function">CLOS:EXTRACT-SPECIALIZER-NAMES</code></a> '((p position) x y))
⇒ <code class="computeroutput">(POSITION T T)</code>
(<a class="link" href="#extract-specializer-names" title="29.6.4.2. Function CLOS:EXTRACT-SPECIALIZER-NAMES"><code class="function">CLOS:EXTRACT-SPECIALIZER-NAMES</code></a> '(a (b (eql x)) c <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> i))
⇒ <code class="computeroutput">(T (EQL X) T)</code>
</pre></div></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="mop-accessors"></a>29.7. Accessor Methods</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-acc-readers">29.7.1. Introspection</a></span></dt><dd><dl><dt><span class="section"><a href="#accessor-method-slotdef">29.7.1.1. Generic Function <code class="function">CLOS:ACCESSOR-METHOD-SLOT-DEFINITION</code></a></span></dt></dl></dd><dt><span class="section"><a href="#mop-acc-customize">29.7.2. Customization</a></span></dt><dd><dl><dt><span class="section"><a href="#reader-method-class">29.7.2.1. Generic Function <code class="function">CLOS:READER-METHOD-CLASS</code></a></span></dt><dt><span class="section"><a href="#writer-method-class">29.7.2.2. Generic Function <code class="function">CLOS:WRITER-METHOD-CLASS</code></a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-acc-readers"></a>29.7.1. Introspection</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#accessor-method-slotdef">29.7.1.1. Generic Function <code class="function">CLOS:ACCESSOR-METHOD-SLOT-DEFINITION</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="accessor-method-slotdef"></a>29.7.1.1. Generic Function <a class="link" href="#accessor-method-slotdef" title="29.7.1.1. Generic Function CLOS:ACCESSOR-METHOD-SLOT-DEFINITION"><code class="function">CLOS:ACCESSOR-METHOD-SLOT-DEFINITION</code></a></h4></div><div><h5 class="subtitle"><code class="code">(<a class="link" href="#accessor-method-slotdef" title="29.7.1.1. Generic Function CLOS:ACCESSOR-METHOD-SLOT-DEFINITION"><code class="function">CLOS:ACCESSOR-METHOD-SLOT-DEFINITION</code></a> <em class="replaceable"><code>method</code></em>)</code></h5></div></div></div><p>This accessor can only be called on accessor methods.  It returns
the <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> that defined this method.  This is the value of the
<code class="constant">:SLOT-DEFINITION</code> initialization argument associated with the method during
initialization.</p><div class="variablelist"><p class="title"><strong>The specified methods for the accessor <a class="link" href="#mop-method-mo">method metaobject</a>
  readers</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#accessor-method-slotdef" title="29.7.1.1. Generic Function CLOS:ACCESSOR-METHOD-SLOT-DEFINITION"><code class="function">CLOS:ACCESSOR-METHOD-SLOT-DEFINITION</code></a>
   (<em class="replaceable"><code>method</code></em> <a class="link" href="#mop-meth-init-mo" title="29.6.3.2. Initialization of method metaobjects"><code class="classname">CLOS:STANDARD-ACCESSOR-METHOD</code></a>))</code></span></span></dt><dd>No behavior is specified for this
   method beyond that which is specified for the generic function.</dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-acc-customize"></a>29.7.2. Customization</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#reader-method-class">29.7.2.1. Generic Function <code class="function">CLOS:READER-METHOD-CLASS</code></a></span></dt><dt><span class="section"><a href="#writer-method-class">29.7.2.2. Generic Function <code class="function">CLOS:WRITER-METHOD-CLASS</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="reader-method-class"></a>29.7.2.1. Generic Function <a class="link" href="#reader-method-class" title="29.7.2.1. Generic Function CLOS:READER-METHOD-CLASS"><code class="function">CLOS:READER-METHOD-CLASS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#reader-method-class" title="29.7.2.1. Generic Function CLOS:READER-METHOD-CLASS"><code class="function">CLOS:READER-METHOD-CLASS</code></a> <em class="replaceable"><code>class</code></em> <em class="replaceable"><code>direct-slot-definition</code></em>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>initargs</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>class</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>direct-slot-definition</code></em></span></dt><dd>a <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>initargs</code></em></span></dt><dd>alternating initialization argument names and values.
</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function is called to determine the
   class of reader methods created during class initialization and
   reinitialization.  The result must be a subclass of
   <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-READER-METHOD</code></a>.</p><p class="simpara">The <em class="replaceable"><code>initargs</code></em> argument must be the same as will be passed
   to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a> to create the reader method.  The <em class="replaceable"><code>initargs</code></em>
   must include <code class="constant">:SLOT-DEFINITION</code> with <em class="replaceable"><code>slot-definition</code></em> as its value.
</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#reader-method-class" title="29.7.2.1. Generic Function CLOS:READER-METHOD-CLASS"><code class="function">CLOS:READER-METHOD-CLASS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>) (<em class="replaceable"><code>direct-slot-definition</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-DIRECT-SLOT-DEFINITION</code></a>)
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>initargs</code></em>)</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#reader-method-class" title="29.7.2.1. Generic Function CLOS:READER-METHOD-CLASS"><code class="function">CLOS:READER-METHOD-CLASS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>) (<em class="replaceable"><code>direct-slot-definition</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-DIRECT-SLOT-DEFINITION</code></a>)
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>initargs</code></em>)</code></span></span></dt><dd><p class="simpara">These methods return the class
   <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-READER-METHOD</code></a>.</p><p class="simpara">These methods can be overridden.</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="writer-method-class"></a>29.7.2.2. Generic Function <a class="link" href="#writer-method-class" title="29.7.2.2. Generic Function CLOS:WRITER-METHOD-CLASS"><code class="function">CLOS:WRITER-METHOD-CLASS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#writer-method-class" title="29.7.2.2. Generic Function CLOS:WRITER-METHOD-CLASS"><code class="function">CLOS:WRITER-METHOD-CLASS</code></a> <em class="replaceable"><code>class</code></em>
    <em class="replaceable"><code>direct-slot</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>initargs</code></em>)
 </code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>class</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>direct-slot</code></em></span></dt><dd>a <a class="link" href="#mop-dsd-mo">direct</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>initargs</code></em></span></dt><dd>a list of initialization arguments and values.
</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a>.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function is called to determine the
   class of writer methods created during class initialization and
   reinitialization.  The result must be a subclass of
   <a class="link" href="#writer-method-class" title="29.7.2.2. Generic Function CLOS:WRITER-METHOD-CLASS"><code class="classname">CLOS:STANDARD-WRITER-METHOD</code></a>.</p><p class="simpara">The <em class="replaceable"><code>initargs</code></em> argument must be the same as will be passed
   to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a> to create the reader method.  The <em class="replaceable"><code>initargs</code></em>
   must include <code class="constant">:SLOT-DEFINITION</code> with <a class="link" href="#mop-sd" title="29.4. Slot Definitions"><code class="classname">CLOS:SLOT-DEFINITION</code></a> as its value.
</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#writer-method-class" title="29.7.2.2. Generic Function CLOS:WRITER-METHOD-CLASS"><code class="function">CLOS:WRITER-METHOD-CLASS</code></a>
    (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>)
    (<em class="replaceable"><code>direct-slot</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-DIRECT-SLOT-DEFINITION</code></a>)
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>initargs</code></em>)</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#writer-method-class" title="29.7.2.2. Generic Function CLOS:WRITER-METHOD-CLASS"><code class="function">CLOS:WRITER-METHOD-CLASS</code></a>
    (<em class="replaceable"><code>class</code></em> <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>)
    (<em class="replaceable"><code>direct-slot</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-DIRECT-SLOT-DEFINITION</code></a>)
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>initargs</code></em>)</code></span></span></dt><dd><p class="simpara">These methods return the class
  <a class="link" href="#writer-method-class" title="29.7.2.2. Generic Function CLOS:WRITER-METHOD-CLASS"><code class="classname">CLOS:STANDARD-WRITER-METHOD</code></a>.</p><p class="simpara">These methods can be overridden.</p></dd></dl></div></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="mop-specializers"></a>29.8. Specializers</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-specializers-inheritance">29.8.1. Inheritance Structure of Specializer Metaobject Classes</a></span></dt><dt><span class="section"><a href="#mop-spec-readers">29.8.2. Introspection</a></span></dt><dd><dl><dt><span class="section"><a href="#eql-specializer-object">29.8.2.1. Function <code class="function">CLOS:EQL-SPECIALIZER-OBJECT</code></a></span></dt></dl></dd><dt><span class="section"><a href="#mop-spec-init">29.8.3. Initialization</a></span></dt><dd><dl><dt><span class="section"><a href="#intern-eql-specializer">29.8.3.1. Function <code class="function">CLOS:INTERN-EQL-SPECIALIZER</code></a></span></dt></dl></dd><dt><span class="section"><a href="#mop-spec-dep">29.8.4. Updating Dependencies</a></span></dt><dd><dl><dt><span class="section"><a href="#specializer-direct-methods">29.8.4.1. Generic Function <code class="function">CLOS:SPECIALIZER-DIRECT-METHODS</code></a></span></dt><dt><span class="section"><a href="#specializer-direct-gfs">29.8.4.2. Generic Function <code class="function">CLOS:SPECIALIZER-DIRECT-GENERIC-FUNCTIONS</code></a></span></dt><dt><span class="section"><a href="#add-direct-method">29.8.4.3. Generic Function <code class="function">CLOS:ADD-DIRECT-METHOD</code></a></span></dt><dt><span class="section"><a href="#remove-direct-method">29.8.4.4. Generic Function <code class="function">CLOS:REMOVE-DIRECT-METHOD</code></a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-specializers-inheritance"></a>29.8.1. Inheritance Structure of Specializer Metaobject Classes</h3></div></div></div><div class="figure"><a id="mop-specializers-inheritance-fig"></a><p class="title"><strong>Figure 29.6. Inheritance structure of specializer metaobject classes</strong></p><div class="figure-contents"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="100%"><tr><td><img src="mop-classes-specializer.png" width="100%" alt="Inheritance structure of specializer metaobject classes" /></td></tr></table></div></div></div><br class="figure-break" /></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-spec-readers"></a>29.8.2. Introspection</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#eql-specializer-object">29.8.2.1. Function <code class="function">CLOS:EQL-SPECIALIZER-OBJECT</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="eql-specializer-object"></a>29.8.2.1. Function <a class="link" href="#eql-specializer-object" title="29.8.2.1. Function CLOS:EQL-SPECIALIZER-OBJECT"><code class="function">CLOS:EQL-SPECIALIZER-OBJECT</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#eql-specializer-object" title="29.8.2.1. Function CLOS:EQL-SPECIALIZER-OBJECT"><code class="function">CLOS:EQL-SPECIALIZER-OBJECT</code></a>
    <em class="replaceable"><code>eql-specializer</code></em>)
</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>eql-specializer</code></em></span></dt><dd>an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typspe_eql.html" target="_top"><code class="classname">EQL</code></a> specializer metaobject.
</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>an object.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This function returns the object associated with
   <em class="replaceable"><code>eql-specializer</code></em> during initialization.
   The value is guaranteed to be <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typspe_eql.html" target="_top"><code class="classname">EQL</code></a> to the value originally passed
   to <a class="link" href="#intern-eql-specializer" title="29.8.3.1. Function CLOS:INTERN-EQL-SPECIALIZER"><code class="function">CLOS:INTERN-EQL-SPECIALIZER</code></a>, but it is not necessarily <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a> to that
   value.</p><p class="simpara">This function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> if
   <em class="replaceable"><code>eql-specializer</code></em> is not an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typspe_eql.html" target="_top"><code class="classname">EQL</code></a>
   specializer.</p></dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-spec-init"></a>29.8.3. Initialization</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#intern-eql-specializer">29.8.3.1. Function <code class="function">CLOS:INTERN-EQL-SPECIALIZER</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="intern-eql-specializer"></a>29.8.3.1. Function <a class="link" href="#intern-eql-specializer" title="29.8.3.1. Function CLOS:INTERN-EQL-SPECIALIZER"><code class="function">CLOS:INTERN-EQL-SPECIALIZER</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#intern-eql-specializer" title="29.8.3.1. Function CLOS:INTERN-EQL-SPECIALIZER"><code class="function">CLOS:INTERN-EQL-SPECIALIZER</code></a>
    <em class="replaceable"><code>object</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>object</code></em></span></dt><dd>any Lisp object.</dd></dl></div></dd><dt><span class="term">Values</span></dt><dd>The <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typspe_eql.html" target="_top"><code class="classname">EQL</code></a> specializer metaobject for <em class="replaceable"><code>object</code></em>.
</dd><dt><span class="term">Purpose</span></dt><dd>This function returns the unique <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typspe_eql.html" target="_top"><code class="classname">EQL</code></a> specializer
   metaobject for <em class="replaceable"><code>object</code></em>, creating one if necessary.  Two calls to
   <a class="link" href="#intern-eql-specializer" title="29.8.3.1. Function CLOS:INTERN-EQL-SPECIALIZER"><code class="function">CLOS:INTERN-EQL-SPECIALIZER</code></a> with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typspe_eql.html" target="_top"><code class="classname">EQL</code></a> arguments will return the same
   (i.e., <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a>) value.</dd></dl></div><p><strong>Remarks. </strong>The result of calling <a class="link" href="#eql-specializer-object" title="29.8.2.1. Function CLOS:EQL-SPECIALIZER-OBJECT"><code class="function">CLOS:EQL-SPECIALIZER-OBJECT</code></a> on the result of a
call to <a class="link" href="#intern-eql-specializer" title="29.8.3.1. Function CLOS:INTERN-EQL-SPECIALIZER"><code class="function">CLOS:INTERN-EQL-SPECIALIZER</code></a> is only guaranteed to be <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typspe_eql.html" target="_top"><code class="classname">EQL</code></a> to the
original <em class="replaceable"><code>object</code></em> argument, not necessarily <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a>.</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-spec-dep"></a>29.8.4. Updating Dependencies</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#specializer-direct-methods">29.8.4.1. Generic Function <code class="function">CLOS:SPECIALIZER-DIRECT-METHODS</code></a></span></dt><dt><span class="section"><a href="#specializer-direct-gfs">29.8.4.2. Generic Function <code class="function">CLOS:SPECIALIZER-DIRECT-GENERIC-FUNCTIONS</code></a></span></dt><dt><span class="section"><a href="#add-direct-method">29.8.4.3. Generic Function <code class="function">CLOS:ADD-DIRECT-METHOD</code></a></span></dt><dt><span class="section"><a href="#remove-direct-method">29.8.4.4. Generic Function <code class="function">CLOS:REMOVE-DIRECT-METHOD</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="specializer-direct-methods"></a>29.8.4.1. Generic Function <a class="link" href="#specializer-direct-methods" title="29.8.4.1. Generic Function CLOS:SPECIALIZER-DIRECT-METHODS"><code class="function">CLOS:SPECIALIZER-DIRECT-METHODS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#specializer-direct-methods" title="29.8.4.1. Generic Function CLOS:SPECIALIZER-DIRECT-METHODS"><code class="function">CLOS:SPECIALIZER-DIRECT-METHODS</code></a>
    <em class="replaceable"><code>specializer</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>specializer</code></em></span></dt><dd>a specializer metaobject.
   </dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>A possibly empty list of <a class="link" href="#mop-method-mo">method metaobject</a>s.
</dd><dt><span class="term">Purpose</span></dt><dd>This generic function returns the possibly empty set
   of those methods, connected to generic functions, which have
   <em class="replaceable"><code>specializer</code></em> as a specializer.  The elements of this set are
   <a class="link" href="#mop-method-mo">method metaobject</a>s.  This value is maintained by the generic
   functions <a class="link" href="#add-direct-method" title="29.8.4.3. Generic Function CLOS:ADD-DIRECT-METHOD"><code class="function">CLOS:ADD-DIRECT-METHOD</code></a> and <a class="link" href="#remove-direct-method" title="29.8.4.4. Generic Function CLOS:REMOVE-DIRECT-METHOD"><code class="function">CLOS:REMOVE-DIRECT-METHOD</code></a>.
</dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#specializer-direct-methods" title="29.8.4.1. Generic Function CLOS:SPECIALIZER-DIRECT-METHODS"><code class="function">CLOS:SPECIALIZER-DIRECT-METHODS</code></a>
   (<em class="replaceable"><code>specializer</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>))</code></span></span></dt><dd><p class="simpara">No behavior is specified for this
   method beyond that which is specified for the generic function.</p><p>This method cannot be overridden unless the
 following methods are overridden as well:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#add-direct-method" title="29.8.4.3. Generic Function CLOS:ADD-DIRECT-METHOD"><code class="function">CLOS:ADD-DIRECT-METHOD</code></a>
      (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a>)</code></span></li><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#remove-direct-method" title="29.8.4.4. Generic Function CLOS:REMOVE-DIRECT-METHOD"><code class="function">CLOS:REMOVE-DIRECT-METHOD</code></a>
      (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a>)</code></span></li><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#specializer-direct-gfs" title="29.8.4.2. Generic Function CLOS:SPECIALIZER-DIRECT-GENERIC-FUNCTIONS"><code class="function">CLOS:SPECIALIZER-DIRECT-GENERIC-FUNCTIONS</code></a>
      (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>)</code></span></li></ul></div></dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#specializer-direct-methods" title="29.8.4.1. Generic Function CLOS:SPECIALIZER-DIRECT-METHODS"><code class="function">CLOS:SPECIALIZER-DIRECT-METHODS</code></a>
   (<em class="replaceable"><code>specializer</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:EQL-SPECIALIZER</code></a>))</code></span></span></dt><dd>No behavior is specified for this
   method beyond that which is specified for the generic function.</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="specializer-direct-gfs"></a>29.8.4.2. Generic Function <a class="link" href="#specializer-direct-gfs" title="29.8.4.2. Generic Function CLOS:SPECIALIZER-DIRECT-GENERIC-FUNCTIONS"><code class="function">CLOS:SPECIALIZER-DIRECT-GENERIC-FUNCTIONS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#specializer-direct-gfs" title="29.8.4.2. Generic Function CLOS:SPECIALIZER-DIRECT-GENERIC-FUNCTIONS"><code class="function">CLOS:SPECIALIZER-DIRECT-GENERIC-FUNCTIONS</code></a>
    <em class="replaceable"><code>specializer</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>specializer</code></em></span></dt><dd>a specializer metaobject.
   </dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>A possibly empty list of <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>s.
</dd><dt><span class="term">Purpose</span></dt><dd>This generic function returns the possibly empty set
   of those generic functions which have a method with <em class="replaceable"><code>specializer</code></em>
   as a specializer.  The elements of this set are <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>s.  This value
   is maintained by the generic functions <a class="link" href="#add-direct-method" title="29.8.4.3. Generic Function CLOS:ADD-DIRECT-METHOD"><code class="function">CLOS:ADD-DIRECT-METHOD</code></a> and
   <a class="link" href="#remove-direct-method" title="29.8.4.4. Generic Function CLOS:REMOVE-DIRECT-METHOD"><code class="function">CLOS:REMOVE-DIRECT-METHOD</code></a>.</dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#specializer-direct-gfs" title="29.8.4.2. Generic Function CLOS:SPECIALIZER-DIRECT-GENERIC-FUNCTIONS"><code class="function">CLOS:SPECIALIZER-DIRECT-GENERIC-FUNCTIONS</code></a>
   (<em class="replaceable"><code>specializer</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>))</code></span></span></dt><dd><p class="simpara">No behavior is specified for this
   method beyond that which is specified for the generic function.</p><p>This method cannot be overridden unless the
 following methods are overridden as well:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#add-direct-method" title="29.8.4.3. Generic Function CLOS:ADD-DIRECT-METHOD"><code class="function">CLOS:ADD-DIRECT-METHOD</code></a>
      (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a>)</code></span></li><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#remove-direct-method" title="29.8.4.4. Generic Function CLOS:REMOVE-DIRECT-METHOD"><code class="function">CLOS:REMOVE-DIRECT-METHOD</code></a>
      (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a>)</code></span></li><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#specializer-direct-methods" title="29.8.4.1. Generic Function CLOS:SPECIALIZER-DIRECT-METHODS"><code class="function">CLOS:SPECIALIZER-DIRECT-METHODS</code></a>
      (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>)</code></span></li></ul></div></dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#specializer-direct-gfs" title="29.8.4.2. Generic Function CLOS:SPECIALIZER-DIRECT-GENERIC-FUNCTIONS"><code class="function">CLOS:SPECIALIZER-DIRECT-GENERIC-FUNCTIONS</code></a>
   (<em class="replaceable"><code>specializer</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:EQL-SPECIALIZER</code></a>))</code></span></span></dt><dd>No behavior is specified for this
   method beyond that which is specified for the generic function.</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="add-direct-method"></a>29.8.4.3. Generic Function <a class="link" href="#add-direct-method" title="29.8.4.3. Generic Function CLOS:ADD-DIRECT-METHOD"><code class="function">CLOS:ADD-DIRECT-METHOD</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#add-direct-method" title="29.8.4.3. Generic Function CLOS:ADD-DIRECT-METHOD"><code class="function">CLOS:ADD-DIRECT-METHOD</code></a>
     <em class="replaceable"><code>specializer</code></em> <em class="replaceable"><code>method</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>specializer</code></em></span></dt><dd>a specializer metaobject.
   </dd><dt><span class="term"><em class="replaceable"><code>method</code></em></span></dt><dd>a <a class="link" href="#mop-method-mo">method metaobject</a>.</dd></dl></div></dd><dt><span class="term">Values</span></dt><dd>The values returned by this generic function are unspecified.
 </dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function is called to maintain a set of
   backpointers from a specializer to the set of methods specialized to
   it.  If <em class="replaceable"><code>method</code></em> is already in the set, it is not added again (no
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed).</p><p class="simpara">This set can be accessed as a list by calling the generic
   function <a class="link" href="#specializer-direct-methods" title="29.8.4.1. Generic Function CLOS:SPECIALIZER-DIRECT-METHODS"><code class="function">CLOS:SPECIALIZER-DIRECT-METHODS</code></a>.  Methods are removed from the
   set by <a class="link" href="#remove-direct-method" title="29.8.4.4. Generic Function CLOS:REMOVE-DIRECT-METHOD"><code class="function">CLOS:REMOVE-DIRECT-METHOD</code></a>.</p><p class="simpara">The generic function <a class="link" href="#add-direct-method" title="29.8.4.3. Generic Function CLOS:ADD-DIRECT-METHOD"><code class="function">CLOS:ADD-DIRECT-METHOD</code></a> is called by
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_add-method.html" target="_top"><code class="function">ADD-METHOD</code></a> whenever a method is added to a generic function.  It is
   called once for each of the specializers of the method.  Note that in
   cases where a specializer appears more than once in the specializers
   of a method, this generic function will be called more than once with
   the same specializer as argument.</p><p class="simpara">The results are undefined if the <em class="replaceable"><code>specializer</code></em> argument
   is not one of the specializers of the <em class="replaceable"><code>method</code></em> argument.
</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#add-direct-method" title="29.8.4.3. Generic Function CLOS:ADD-DIRECT-METHOD"><code class="function">CLOS:ADD-DIRECT-METHOD</code></a>
   (<em class="replaceable"><code>specializer</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>) (<em class="replaceable"><code>method</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a>))</code></span></span></dt><dd><p class="simpara">This method implements the behavior of the generic
   function for class specializers.</p><p class="simpara">No behavior is specified for this
   method beyond that which is specified for the generic function.</p><p>This method cannot be overridden unless the
 following methods are overridden as well:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#remove-direct-method" title="29.8.4.4. Generic Function CLOS:REMOVE-DIRECT-METHOD"><code class="function">CLOS:REMOVE-DIRECT-METHOD</code></a>
       (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a>)</code></span></li><li class="listitem"><span class="method"><code class="literal">
       <a class="link" href="#specializer-direct-gfs" title="29.8.4.2. Generic Function CLOS:SPECIALIZER-DIRECT-GENERIC-FUNCTIONS"><code class="function">CLOS:SPECIALIZER-DIRECT-GENERIC-FUNCTIONS</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>)</code></span></li><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#specializer-direct-methods" title="29.8.4.1. Generic Function CLOS:SPECIALIZER-DIRECT-METHODS"><code class="function">CLOS:SPECIALIZER-DIRECT-METHODS</code></a>
       (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>)</code></span></li></ul></div><p>
</p></dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#add-direct-method" title="29.8.4.3. Generic Function CLOS:ADD-DIRECT-METHOD"><code class="function">CLOS:ADD-DIRECT-METHOD</code></a>
   (<em class="replaceable"><code>specializer</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:EQL-SPECIALIZER</code></a>)
   (<em class="replaceable"><code>method</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a>))</code></span></span></dt><dd><p class="simpara">This method implements the behavior of the generic
   function for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typspe_eql.html" target="_top"><code class="classname">EQL</code></a> specializers.</p><p class="simpara">No behavior is specified for this
   method beyond that which is specified for the generic function.</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="remove-direct-method"></a>29.8.4.4. Generic Function <a class="link" href="#remove-direct-method" title="29.8.4.4. Generic Function CLOS:REMOVE-DIRECT-METHOD"><code class="function">CLOS:REMOVE-DIRECT-METHOD</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#remove-direct-method" title="29.8.4.4. Generic Function CLOS:REMOVE-DIRECT-METHOD"><code class="function">CLOS:REMOVE-DIRECT-METHOD</code></a> <em class="replaceable"><code>specializer</code></em>
    <em class="replaceable"><code>method</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>specializer</code></em></span></dt><dd>a specializer metaobject.
   </dd><dt><span class="term"><em class="replaceable"><code>method</code></em></span></dt><dd>a <a class="link" href="#mop-method-mo">method metaobject</a>.</dd></dl></div></dd><dt><span class="term">Values</span></dt><dd>The values returned by this generic function are unspecified.
 </dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function is called to maintain a set of
   backpointers from a specializer to the set of methods specialized to
   it.  If <em class="replaceable"><code>method</code></em> is in the set it is removed.  If it is not, no
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.</p><p class="simpara">This set can be accessed as a list by calling the generic
   function <a class="link" href="#specializer-direct-methods" title="29.8.4.1. Generic Function CLOS:SPECIALIZER-DIRECT-METHODS"><code class="function">CLOS:SPECIALIZER-DIRECT-METHODS</code></a>.  Methods are added to the set
   by <a class="link" href="#add-direct-method" title="29.8.4.3. Generic Function CLOS:ADD-DIRECT-METHOD"><code class="function">CLOS:ADD-DIRECT-METHOD</code></a>.</p><p class="simpara">The generic function <a class="link" href="#remove-direct-method" title="29.8.4.4. Generic Function CLOS:REMOVE-DIRECT-METHOD"><code class="function">CLOS:REMOVE-DIRECT-METHOD</code></a> is called by
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_remove-method.html" target="_top"><code class="function">REMOVE-METHOD</code></a> whenever a method is removed from a generic function.
   It is called once for each of the specializers of the method.  Note
   that in cases where a specializer appears more than once in the
   specializers of a method, this generic function will be called more
   than once with the same specializer as argument.</p><p class="simpara">The results are undefined if the <em class="replaceable"><code>specializer</code></em> argument is
   not one of the specializers of the <em class="replaceable"><code>method</code></em> argument.
</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#remove-direct-method" title="29.8.4.4. Generic Function CLOS:REMOVE-DIRECT-METHOD"><code class="function">CLOS:REMOVE-DIRECT-METHOD</code></a>
   (<em class="replaceable"><code>specializer</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>) (<em class="replaceable"><code>method</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a>))</code></span></span></dt><dd><p class="simpara">This method implements the behavior of the generic
   function for class specializers.</p><p class="simpara">No behavior is specified for this
   method beyond that which is specified for the generic function.</p><p>This method cannot be overridden unless the
 following methods are overridden as well:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#add-direct-method" title="29.8.4.3. Generic Function CLOS:ADD-DIRECT-METHOD"><code class="function">CLOS:ADD-DIRECT-METHOD</code></a>
       (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a>)</code></span></li><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#specializer-direct-gfs" title="29.8.4.2. Generic Function CLOS:SPECIALIZER-DIRECT-GENERIC-FUNCTIONS"><code class="function">CLOS:SPECIALIZER-DIRECT-GENERIC-FUNCTIONS</code></a>
       (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>)</code></span></li><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#specializer-direct-methods" title="29.8.4.1. Generic Function CLOS:SPECIALIZER-DIRECT-METHODS"><code class="function">CLOS:SPECIALIZER-DIRECT-METHODS</code></a>
       (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a>)</code></span></li></ul></div></dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#remove-direct-method" title="29.8.4.4. Generic Function CLOS:REMOVE-DIRECT-METHOD"><code class="function">CLOS:REMOVE-DIRECT-METHOD</code></a>
   (<em class="replaceable"><code>specializer</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:EQL-SPECIALIZER</code></a>)
   (<em class="replaceable"><code>method</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a>))</code></span></span></dt><dd><p class="simpara">This method implements the behavior of the generic
   function for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typspe_eql.html" target="_top"><code class="classname">EQL</code></a> specializers.</p><p class="simpara">No behavior is specified for this
   method beyond that which is specified for the generic function.</p></dd></dl></div></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="mop-meth-comb"></a>29.9. Method Combinations</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-meth-comb-inheritance">29.9.1. Inheritance Structure of method combination metaobject Classes</a></span></dt><dt><span class="section"><a href="#mop-meth-comb-customize">29.9.2. Customization</a></span></dt><dd><dl><dt><span class="section"><a href="#find-method-combination">29.9.2.1. Generic Function <code class="function">CLOS:FIND-METHOD-COMBINATION</code></a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-meth-comb-inheritance"></a>29.9.1. Inheritance Structure of <a class="link" href="#mop-meth-comp-mo">method combination metaobject</a> Classes</h3></div></div></div><div class="figure"><a id="mop-meth-comb-inheritance-fig"></a><p class="title"><strong>Figure 29.7. Inheritance structure of method combination metaobject classes</strong></p><div class="figure-contents"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="100%"><tr><td><img src="mop-classes-methcomb.png" width="100%" alt="Inheritance structure of method combination metaobject classes" /></td></tr></table></div></div></div><br class="figure-break" /></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-meth-comb-customize"></a>29.9.2. Customization</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#find-method-combination">29.9.2.1. Generic Function <code class="function">CLOS:FIND-METHOD-COMBINATION</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="find-method-combination"></a>29.9.2.1. Generic Function <a class="link" href="#find-method-combination" title="29.9.2.1. Generic Function CLOS:FIND-METHOD-COMBINATION"><code class="function">CLOS:FIND-METHOD-COMBINATION</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#find-method-combination" title="29.9.2.1. Generic Function CLOS:FIND-METHOD-COMBINATION"><code class="function">CLOS:FIND-METHOD-COMBINATION</code></a> <em class="replaceable"><code>generic-function</code></em>
    <em class="replaceable"><code>method-combination-type-name</code></em>
    <em class="replaceable"><code>method-combination-options</code></em>)
</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>generic-function</code></em></span></dt><dd>a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>method-combination-type-name</code></em></span></dt><dd>a symbol which names a type of method combination.
   </dd><dt><span class="term"><em class="replaceable"><code>method-combination-options</code></em></span></dt><dd>a list of arguments to the method combination type.
</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>A <a class="link" href="#mop-meth-comp-mo">method combination metaobject</a>.</dd><dt><span class="term">Purpose</span></dt><dd>This generic function is called to determine the
   method combination object used by a generic function.
</dd></dl></div><p><strong>Remarks. </strong>Further details of <a class="link" href="#mop-meth-comp-mo">method combination metaobject</a>s are not specified.
</p></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="mop-slot-access"></a>29.10. Slot Access</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-sa-instance-struct">29.10.1. Instance Structure Protocol</a></span></dt><dt><span class="section"><a href="#mop-sa-funcallable">29.10.2. Funcallable Instances</a></span></dt><dt><span class="section"><a href="#mop-sa-customize">29.10.3. Customization</a></span></dt><dd><dl><dt><span class="section"><a href="#standard-instance-access">29.10.3.1. Function <code class="function">CLOS:STANDARD-INSTANCE-ACCESS</code></a></span></dt><dt><span class="section"><a href="#funcallable-standard-instance-access">29.10.3.2. Function <code class="function">CLOS:FUNCALLABLE-STANDARD-INSTANCE-ACCESS</code></a></span></dt><dt><span class="section"><a href="#set-fif">29.10.3.3. Function <code class="function">CLOS:SET-FUNCALLABLE-INSTANCE-FUNCTION</code></a></span></dt><dt><span class="section"><a href="#slot-value-UC">29.10.3.4. Generic Function <code class="function">CLOS:SLOT-VALUE-USING-CLASS</code></a></span></dt><dt><span class="section"><a href="#setf-slot-value-UC">29.10.3.5. Generic Function <code class="code">(SETF CLOS:SLOT-VALUE-USING-CLASS)</code></a></span></dt><dt><span class="section"><a href="#slot-boundp-UC">29.10.3.6. Generic Function <code class="function">CLOS:SLOT-BOUNDP-USING-CLASS</code></a></span></dt><dt><span class="section"><a href="#slot-makunbound-UC">29.10.3.7. Generic Function <code class="function">CLOS:SLOT-MAKUNBOUND-USING-CLASS</code></a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-sa-instance-struct"></a>29.10.1. Instance Structure Protocol</h3></div></div></div><p>The instance structure protocol is responsible for implementing
the behavior of the slot access functions like <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_slot-value.html" target="_top"><code class="function">SLOT-VALUE</code></a> and
<code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_slot-value.html" target="_top"><code class="function">SLOT-VALUE</code></a>)</code>.</p><p>For each <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> slot access function other than <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_slot-exists-p.html" target="_top"><code class="function">SLOT-EXISTS-P</code></a>,
there is a corresponding generic function which actually provides the
behavior of the function.  When called, the slot access function finds
the pertinent <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>, calls the corresponding generic function and
returns its result.  The arguments passed on to the generic function
include one additional value, the class of the <em class="replaceable"><code>object</code></em> argument,
which always immediately precedes the <em class="replaceable"><code>object</code></em> argument.</p><div class="table"><a id="mop-sa-instance-struct-table"></a><p class="title"><strong>Table 29.6. The correspondence between slot access function and
  underlying slot access generic function</strong></p><div class="table-contents"><table class="table" summary="The correspondence between slot access function and&#10;  underlying slot access generic function" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="center">Slot Access Function</th><th align="center">Corresponding
    Slot Access Generic Function</th></tr></thead><tbody><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_slot-value.html" target="_top"><code class="function">SLOT-VALUE</code></a> <em class="replaceable"><code>object</code></em> <em class="replaceable"><code>slot-name</code></em></td><td align="center"><a class="link" href="#slot-value-UC" title="29.10.3.4. Generic Function CLOS:SLOT-VALUE-USING-CLASS"><code class="function">CLOS:SLOT-VALUE-USING-CLASS</code></a> <em class="replaceable"><code>class</code></em> <em class="replaceable"><code>object</code></em> <em class="replaceable"><code>slot</code></em></td></tr><tr><td align="center"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_slot-value.html" target="_top"><code class="function">SLOT-VALUE</code></a>)</code> <em class="replaceable"><code>new-value</code></em> <em class="replaceable"><code>object</code></em> <em class="replaceable"><code>slot-name</code></em></td><td align="center"><a class="link" href="#setf-slot-value-UC" title="29.10.3.5. Generic Function (SETF CLOS:SLOT-VALUE-USING-CLASS)"><code class="code">(SETF CLOS:SLOT-VALUE-USING-CLASS)</code></a> <em class="replaceable"><code>new-value</code></em> <em class="replaceable"><code>class</code></em> <em class="replaceable"><code>object</code></em> <em class="replaceable"><code>slot</code></em></td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_slot-boundp.html" target="_top"><code class="function">SLOT-BOUNDP</code></a> <em class="replaceable"><code>object</code></em> <em class="replaceable"><code>slot-name</code></em></td><td align="center"><a class="link" href="#slot-boundp-UC" title="29.10.3.6. Generic Function CLOS:SLOT-BOUNDP-USING-CLASS"><code class="function">CLOS:SLOT-BOUNDP-USING-CLASS</code></a> <em class="replaceable"><code>class</code></em> <em class="replaceable"><code>object</code></em> <em class="replaceable"><code>slot</code></em></td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_slot-makunbound.html" target="_top"><code class="function">SLOT-MAKUNBOUND</code></a> <em class="replaceable"><code>object</code></em> <em class="replaceable"><code>slot-name</code></em></td><td align="center"><a class="link" href="#slot-makunbound-UC" title="29.10.3.7. Generic Function CLOS:SLOT-MAKUNBOUND-USING-CLASS"><code class="function">CLOS:SLOT-MAKUNBOUND-USING-CLASS</code></a> <em class="replaceable"><code>class</code></em> <em class="replaceable"><code>object</code></em> <em class="replaceable"><code>slot</code></em></td></tr></tbody></table></div></div><br class="table-break" /><p>At the lowest level, the instance structure protocol provides only
limited mechanisms for portable programs to control the implementation
of instances and to directly access the storage associated with
instances without going through the indirection of slot access.  This is
done to allow portable programs to perform certain commonly requested
slot access optimizations.</p><p>In particular, portable programs can control the implementation
of, and obtain direct access to, slots with allocation <code class="constant">:INSTANCE</code> and
type <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>.  These are called <strong class="first"><em class="firstterm">directly accessible slots
  <a id="slot-directly-accessible" class="indexterm"></a></em></strong>.</p><p>The relevant specified around-method on <a class="link" href="#compute-slots" title="29.3.6.11. Generic Function CLOS:COMPUTE-SLOTS"><code class="function">CLOS:COMPUTE-SLOTS</code></a> determines
the implementation of instances by deciding how each slot in the
instance will be stored.  For each directly accessible slot, this method
allocates a <strong class="first"><em class="firstterm">location
  <a id="slot-location" class="indexterm"></a>
 </em></strong> and associates it with the <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>.
The location can be accessed by calling the <a class="link" href="#slotdef-location" title="29.4.2.4.1. Generic Function CLOS:SLOT-DEFINITION-LOCATION"><code class="function">CLOS:SLOT-DEFINITION-LOCATION</code></a>
generic function.  Locations are non-negative integers.  For a given
class, the locations increase consecutively, in the order that the
directly accessible slots appear in the list of effective slots.  (Note
that here, the next paragraph, and the specification of this
around-method are the only places where the value returned by
<a class="link" href="#compute-slots" title="29.3.6.11. Generic Function CLOS:COMPUTE-SLOTS"><code class="function">CLOS:COMPUTE-SLOTS</code></a> is described as a list rather than a set.)</p><p>Given the location of a directly accessible slot, the value of
that slot in an instance can be accessed with the appropriate accessor.
For <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>, this accessor is the function
<a class="link" href="#standard-instance-access" title="29.10.3.1. Function CLOS:STANDARD-INSTANCE-ACCESS"><code class="function">CLOS:STANDARD-INSTANCE-ACCESS</code></a>.  For <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>, this
accessor is the function <a class="link" href="#funcallable-standard-instance-access" title="29.10.3.2. Function CLOS:FUNCALLABLE-STANDARD-INSTANCE-ACCESS"><code class="function">CLOS:FUNCALLABLE-STANDARD-INSTANCE-ACCESS</code></a>.
In each case, the arguments to the accessor are the instance and the
slot location, in that order.  See the definition of each accessor for
additional restrictions on the use of these function.</p><p>Portable programs are permitted to affect and rely on the
allocation of locations only in the following limited way: By first
defining a portable primary method on <a class="link" href="#compute-slots" title="29.3.6.11. Generic Function CLOS:COMPUTE-SLOTS"><code class="function">CLOS:COMPUTE-SLOTS</code></a> which orders the
returned value in a predictable way, and then relying on the defined
behavior of the specified around-method to assign locations to all
directly accessible slots.  Portable programs may compile-in calls to
low-level accessors which take advantage of the resulting predictable
allocation of slot locations.</p><div class="informalexample"><a id="mop-sa-instance-struct-ex"></a><p>This example shows the use of this mechanism to implement a new
<a class="link" href="#mop-class-mo">class metaobject</a> class, <code class="classname">ordered-class</code> and class
option <code class="constant">:SLOT-ORDER</code>.  This option provides control
over the allocation of slot locations.  In this simple example
implementation, the <code class="constant">:SLOT-ORDER</code> option is not
inherited by subclasses; it controls only instances of the class
itself.
</p><pre class="programlisting">
(defclass ordered-class (standard-class)
  ((slot-order :initform ()
               :initarg :slot-order
               :reader class-slot-order)))

(defmethod compute-slots ((class ordered-class))
  (let ((order (class-slot-order class)))
    (sort (copy-list (call-next-method))
          #'(lambda (a b)
              (&lt; (position (slot-definition-name a) order)
                 (position (slot-definition-name a) order))))))
</pre><p>

Following is the source code the user of this extension would write.
Note that because the code above does not implement inheritance of
the <code class="constant">:SLOT-ORDER</code> option, the function
<code class="function">distance</code> must not be called on instances of
subclasses of <code class="classname">point</code>; it can only be called on
instances of <code class="classname">point</code> itself.

</p><pre class="programlisting">
(defclass point ()
  ((x :initform 0)
   (y :initform 0))
  (:metaclass ordered-class)
  (:slot-order x y))

(defun distance (point)
  (sqrt (/ (+ (expt (standard-instance-access point 0) 2)
              (expt (standard-instance-access point 1) 2))
           2.0)))
</pre><p>

</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>You cannot assume that the slot-location
  values start at 0.  In class <code class="classname">point</code>, for
  example, <em class="replaceable"><code>x</code></em> and <em class="replaceable"><code>y</code></em> will be at slot locations 1 and 2, not 0 and
  1.</p></div><p>

In more realistic uses of this mechanism, the calls to the low-level
instance structure accessors would not actually appear textually in the
source program, but rather would be generated by a meta-level analysis
program run during the process of compiling the source program.
</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-sa-funcallable"></a>29.10.2. Funcallable Instances</h3></div></div></div><p>Instances of classes which are themselves instances of
<a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a> or one of its subclasses are called
<strong class="first"><em class="firstterm">funcallable instances</em></strong>.
Funcallable instances can only be created by
<span class="method"><code class="literal"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_all_ate-instance.html" target="_top"><code class="function">ALLOCATE-INSTANCE</code></a>
 (<a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>)</code></span>.</p><p>Like standard instances, funcallable instances have slots with the
normal behavior.  They differ from standard instances in that they can
be used as functions as well; that is, they can be passed to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_funcall.html" target="_top"><code class="function">FUNCALL</code></a>
and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_apply.html" target="_top"><code class="function">APPLY</code></a>, and they can be stored as the definition of a function
name.  Associated with each funcallable instance is the function which
it runs when it is called.  This function can be changed with
<a class="link" href="#set-fif" title="29.10.3.3. Function CLOS:SET-FUNCALLABLE-INSTANCE-FUNCTION"><code class="function">CLOS:SET-FUNCALLABLE-INSTANCE-FUNCTION</code></a>.</p><div class="informalexample"><a id="mop-sa-funcallable-ex"></a><p>The following simple example shows the use of funcallable
instances to create a simple, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defstruct.html" target="_top"><code class="function">DEFSTRUCT</code></a>-like facility.  (Funcallable
instances are useful when a program needs to construct and maintain a
set of functions and information about those functions.  They make it
possible to maintain both as the same object rather than two separate
objects linked, for example, by hash tables.)

</p><pre class="programlisting">
(defclass constructor ()
  ((name :initarg :name :accessor constructor-name)
   (fields :initarg :fields :accessor constructor-fields))
  (:metaclass funcallable-standard-class))
⇒ <code class="computeroutput">#&gt;FUNCALLABLE-STANDARD-CLASS CONSTRUCTOR&gt;</code>
(defmethod initialize-instance :after ((c constructor) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>)
  (with-slots (name fields) c
    (set-funcallable-instance-function
      c
      #'(lambda ()
          (let ((new (make-array (1+ (length fields)))))
            (setf (aref new 0) name)
            new)))))
⇒ <code class="computeroutput">#&lt;STANDARD-METHOD :AFTER (#&lt;FUNCALLABLE-STANDARD-CLASS CONSTRUCTOR&gt;)&gt;</code>
(setq c1 (make-instance 'constructor :name 'position :fields '(x y)))
⇒ <code class="computeroutput">#&lt;CONSTRUCTOR #&lt;UNBOUND&gt;&gt;</code>
(setq p1 (funcall c1))
⇒ <code class="computeroutput">#(POSITION NIL NIL)</code>
</pre></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-sa-customize"></a>29.10.3. Customization</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#standard-instance-access">29.10.3.1. Function <code class="function">CLOS:STANDARD-INSTANCE-ACCESS</code></a></span></dt><dt><span class="section"><a href="#funcallable-standard-instance-access">29.10.3.2. Function <code class="function">CLOS:FUNCALLABLE-STANDARD-INSTANCE-ACCESS</code></a></span></dt><dt><span class="section"><a href="#set-fif">29.10.3.3. Function <code class="function">CLOS:SET-FUNCALLABLE-INSTANCE-FUNCTION</code></a></span></dt><dt><span class="section"><a href="#slot-value-UC">29.10.3.4. Generic Function <code class="function">CLOS:SLOT-VALUE-USING-CLASS</code></a></span></dt><dt><span class="section"><a href="#setf-slot-value-UC">29.10.3.5. Generic Function <code class="code">(SETF CLOS:SLOT-VALUE-USING-CLASS)</code></a></span></dt><dt><span class="section"><a href="#slot-boundp-UC">29.10.3.6. Generic Function <code class="function">CLOS:SLOT-BOUNDP-USING-CLASS</code></a></span></dt><dt><span class="section"><a href="#slot-makunbound-UC">29.10.3.7. Generic Function <code class="function">CLOS:SLOT-MAKUNBOUND-USING-CLASS</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="standard-instance-access"></a>29.10.3.1. Function <a class="link" href="#standard-instance-access" title="29.10.3.1. Function CLOS:STANDARD-INSTANCE-ACCESS"><code class="function">CLOS:STANDARD-INSTANCE-ACCESS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#standard-instance-access" title="29.10.3.1. Function CLOS:STANDARD-INSTANCE-ACCESS"><code class="function">CLOS:STANDARD-INSTANCE-ACCESS</code></a>
    <em class="replaceable"><code>instance</code></em> <em class="replaceable"><code>location</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>instance</code></em></span></dt><dd>an object.</dd><dt><span class="term"><em class="replaceable"><code>location</code></em></span></dt><dd>a slot location</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>an object.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This function is called to provide direct access to
   a slot in an instance.  By usurping the normal slot lookup protocol,
   this function is intended to provide highly optimized access to the
   slots associated with an instance.</p><p>The following restrictions apply to the use of this function:
   </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The <em class="replaceable"><code>instance</code></em> argument must be a
      standard instance (it must have been returned by
      <span class="method"><code class="literal"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_all_ate-instance.html" target="_top"><code class="function">ALLOCATE-INSTANCE</code></a>(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>)</code></span>).
    </li><li class="listitem">The <em class="replaceable"><code>instance</code></em> argument cannot be an
      non-updated obsolete instance.</li><li class="listitem">The <em class="replaceable"><code>location</code></em> argument must be a location of
      one of the directly accessible slots of the instance's class.
    </li><li class="listitem">The slot must be bound.
  </li></ul></div><p class="simpara">The results are undefined if any of
 these restrictions are violated.</p></dd></dl></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>The second and third restrictions do not
  apply in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.  <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>'s implementation supports non-updated
  obsolete instances and also supports slots with allocation <code class="constant">:CLASS</code>.
</p></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="funcallable-standard-instance-access"></a>29.10.3.2. Function <a class="link" href="#funcallable-standard-instance-access" title="29.10.3.2. Function CLOS:FUNCALLABLE-STANDARD-INSTANCE-ACCESS"><code class="function">CLOS:FUNCALLABLE-STANDARD-INSTANCE-ACCESS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#funcallable-standard-instance-access" title="29.10.3.2. Function CLOS:FUNCALLABLE-STANDARD-INSTANCE-ACCESS"><code class="function">CLOS:FUNCALLABLE-STANDARD-INSTANCE-ACCESS</code></a>
    <em class="replaceable"><code>instance</code></em> <em class="replaceable"><code>location</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>instance</code></em></span></dt><dd>an object.</dd><dt><span class="term"><em class="replaceable"><code>location</code></em></span></dt><dd>a slot location</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>an object.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This function is called to provide direct access to
   a slot in an instance.  By usurping the normal slot lookup protocol,
   this function is intended to provide highly optimized access to the
   slots associated with an instance.</p><p>The following restrictions apply to the use of this function:
   </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The <em class="replaceable"><code>instance</code></em> argument must be a
      funcallable instance (it must have been returned by
      <span class="method"><code class="literal"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_all_ate-instance.html" target="_top"><code class="function">ALLOCATE-INSTANCE</code></a>
       (<a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>)</code></span>).</li><li class="listitem">The <em class="replaceable"><code>instance</code></em> argument cannot be an
      non-updated obsolete instance.</li><li class="listitem">The <em class="replaceable"><code>location</code></em> argument must be a location of
      one of the directly accessible slots of the instance's class.
    </li><li class="listitem">The slot must be bound.
  </li></ul></div><p class="simpara">The results are undefined if any of
 these restrictions are violated.</p></dd></dl></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Implementation dependent: only in <span class="command"><strong>CLISP</strong></span></h3><p>The second and third restrictions do not
  apply in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.  <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>'s implementation supports non-updated
  obsolete instances and also supports slots with allocation <code class="constant">:CLASS</code>.
</p></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="set-fif"></a>29.10.3.3. Function <a class="link" href="#set-fif" title="29.10.3.3. Function CLOS:SET-FUNCALLABLE-INSTANCE-FUNCTION"><code class="function">CLOS:SET-FUNCALLABLE-INSTANCE-FUNCTION</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#set-fif" title="29.10.3.3. Function CLOS:SET-FUNCALLABLE-INSTANCE-FUNCTION"><code class="function">CLOS:SET-FUNCALLABLE-INSTANCE-FUNCTION</code></a>
    <em class="replaceable"><code>funcallable-instance</code></em> <em class="replaceable"><code>function</code></em>)
</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>funcallable-instance</code></em></span></dt><dd>a funcallable instance (it must have been returned by
      <span class="method"><code class="literal"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_all_ate-instance.html" target="_top"><code class="function">ALLOCATE-INSTANCE</code></a>
       (<a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>)</code></span>).
   </dd><dt><span class="term"><em class="replaceable"><code>function</code></em></span></dt><dd>A function.</dd></dl></div></dd><dt><span class="term">Values</span></dt><dd>The values returned by this generic function are unspecified.
 </dd><dt><span class="term">Purpose</span></dt><dd>This function is called to set or to change the
   function of a funcallable instance.  After
   <a class="link" href="#set-fif" title="29.10.3.3. Function CLOS:SET-FUNCALLABLE-INSTANCE-FUNCTION"><code class="function">CLOS:SET-FUNCALLABLE-INSTANCE-FUNCTION</code></a> is called, any subsequent calls
   to <em class="replaceable"><code>funcallable-instance</code></em> will run the new
   function.</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="slot-value-UC"></a>29.10.3.4. Generic Function <a class="link" href="#slot-value-UC" title="29.10.3.4. Generic Function CLOS:SLOT-VALUE-USING-CLASS"><code class="function">CLOS:SLOT-VALUE-USING-CLASS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#slot-value-UC" title="29.10.3.4. Generic Function CLOS:SLOT-VALUE-USING-CLASS"><code class="function">CLOS:SLOT-VALUE-USING-CLASS</code></a> <em class="replaceable"><code>class</code></em>
    <em class="replaceable"><code>object</code></em> <em class="replaceable"><code>slot</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>class</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a> - the class of the
    <em class="replaceable"><code>object</code></em> argument.</dd><dt><span class="term"><em class="replaceable"><code>object</code></em></span></dt><dd>an object.</dd><dt><span class="term"><em class="replaceable"><code>slot</code></em></span></dt><dd>an <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>.</dd></dl></div></dd><dt><span class="term">Values</span></dt><dd>an object.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function implements the behavior of the
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_slot-value.html" target="_top"><code class="function">SLOT-VALUE</code></a> function.  It is called by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_slot-value.html" target="_top"><code class="function">SLOT-VALUE</code></a> with the class
   of <em class="replaceable"><code>object</code></em> as its first argument and the pertinent <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> as its
   third argument.</p><p class="simpara">The generic function <a class="link" href="#slot-value-UC" title="29.10.3.4. Generic Function CLOS:SLOT-VALUE-USING-CLASS"><code class="function">CLOS:SLOT-VALUE-USING-CLASS</code></a> returns the value
   contained in the given slot of the given object.  If the slot is
   unbound, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_slot-unbound.html" target="_top"><code class="function">SLOT-UNBOUND</code></a> is called.</p><p class="simpara">The results are undefined if
 the <em class="replaceable"><code>class</code></em> argument is not the class of the <em class="replaceable"><code>object</code></em> argument, or
 if the <em class="replaceable"><code>slot</code></em> argument does not appear among the set of effective
 slots associated with the <em class="replaceable"><code>class</code></em> argument.</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#slot-value-UC" title="29.10.3.4. Generic Function CLOS:SLOT-VALUE-USING-CLASS"><code class="function">CLOS:SLOT-VALUE-USING-CLASS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>) <em class="replaceable"><code>object</code></em>
   (<em class="replaceable"><code>slot</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-EFFECTIVE-SLOT-DEFINITION</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#slot-value-UC" title="29.10.3.4. Generic Function CLOS:SLOT-VALUE-USING-CLASS"><code class="function">CLOS:SLOT-VALUE-USING-CLASS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>) <em class="replaceable"><code>object</code></em>
   (<em class="replaceable"><code>slot</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-EFFECTIVE-SLOT-DEFINITION</code></a>))</code></span></span></dt><dd><p class="simpara">These methods implement
 the full behavior of this generic function for slots with allocation
 <code class="constant">:INSTANCE</code> and <code class="constant">:CLASS</code>.  If the supplied slot has an allocation
 other than <code class="constant">:INSTANCE</code> or <code class="constant">:CLASS</code> an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.</p><p class="simpara">Overriding these methods is permitted,
 but may require overriding other methods in the standard implementation
 of the slot access protocol.</p></dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#slot-value-UC" title="29.10.3.4. Generic Function CLOS:SLOT-VALUE-USING-CLASS"><code class="function">CLOS:SLOT-VALUE-USING-CLASS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_built-in-class.html" target="_top"><code class="classname">BUILT-IN-CLASS</code></a>) <em class="replaceable"><code>object</code></em> <em class="replaceable"><code>slot</code></em>)</code></span></span></dt><dd>This method <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="setf-slot-value-UC"></a>29.10.3.5. Generic Function <a class="link" href="#setf-slot-value-UC" title="29.10.3.5. Generic Function (SETF CLOS:SLOT-VALUE-USING-CLASS)"><code class="code">(SETF CLOS:SLOT-VALUE-USING-CLASS)</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#setf-slot-value-UC" title="29.10.3.5. Generic Function (SETF CLOS:SLOT-VALUE-USING-CLASS)"><code class="code">(SETF CLOS:SLOT-VALUE-USING-CLASS)</code></a> <em class="replaceable"><code>new-value</code></em> <em class="replaceable"><code>class</code></em>
    <em class="replaceable"><code>object</code></em> <em class="replaceable"><code>slot</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>new-value</code></em></span></dt><dd>an object.</dd><dt><span class="term"><em class="replaceable"><code>class</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a> - the class of the
    <em class="replaceable"><code>object</code></em> argument.</dd><dt><span class="term"><em class="replaceable"><code>object</code></em></span></dt><dd>an object.</dd><dt><span class="term"><em class="replaceable"><code>slot</code></em></span></dt><dd>an <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>.</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>The <em class="replaceable"><code>new-value</code></em> argument.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">The generic function <a class="link" href="#setf-slot-value-UC" title="29.10.3.5. Generic Function (SETF CLOS:SLOT-VALUE-USING-CLASS)"><code class="code">(SETF CLOS:SLOT-VALUE-USING-CLASS)</code></a> implements
   the behavior of the <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_slot-value.html" target="_top"><code class="function">SLOT-VALUE</code></a>)</code> function. It is called by
   <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_slot-value.html" target="_top"><code class="function">SLOT-VALUE</code></a>)</code> with the class of <em class="replaceable"><code>object</code></em> as its second argument
   and the pertinent <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> as its fourth argument.</p><p class="simpara">The generic function <a class="link" href="#setf-slot-value-UC" title="29.10.3.5. Generic Function (SETF CLOS:SLOT-VALUE-USING-CLASS)"><code class="code">(SETF CLOS:SLOT-VALUE-USING-CLASS)</code></a> sets the value
   contained in the given slot of the given object to the given new
   value; any previous value is lost.</p><p class="simpara">The results are undefined if
 the <em class="replaceable"><code>class</code></em> argument is not the class of the <em class="replaceable"><code>object</code></em> argument, or
 if the <em class="replaceable"><code>slot</code></em> argument does not appear among the set of effective
 slots associated with the <em class="replaceable"><code>class</code></em> argument.</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#setf-slot-value-UC" title="29.10.3.5. Generic Function (SETF CLOS:SLOT-VALUE-USING-CLASS)"><code class="code">(SETF CLOS:SLOT-VALUE-USING-CLASS)</code></a>
   <em class="replaceable"><code>new-value</code></em> (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>) <em class="replaceable"><code>object</code></em>
   (<em class="replaceable"><code>slot</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-EFFECTIVE-SLOT-DEFINITION</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#setf-slot-value-UC" title="29.10.3.5. Generic Function (SETF CLOS:SLOT-VALUE-USING-CLASS)"><code class="code">(SETF CLOS:SLOT-VALUE-USING-CLASS)</code></a>
   <em class="replaceable"><code>new-value</code></em> (<em class="replaceable"><code>class</code></em> <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>) <em class="replaceable"><code>object</code></em>
   (<em class="replaceable"><code>slot</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-EFFECTIVE-SLOT-DEFINITION</code></a>))</code></span></span></dt><dd><p class="simpara">These methods implement
 the full behavior of this generic function for slots with allocation
 <code class="constant">:INSTANCE</code> and <code class="constant">:CLASS</code>.  If the supplied slot has an allocation
 other than <code class="constant">:INSTANCE</code> or <code class="constant">:CLASS</code> an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.</p><p class="simpara">Overriding these methods is permitted,
 but may require overriding other methods in the standard implementation
 of the slot access protocol.</p></dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#setf-slot-value-UC" title="29.10.3.5. Generic Function (SETF CLOS:SLOT-VALUE-USING-CLASS)"><code class="code">(SETF CLOS:SLOT-VALUE-USING-CLASS)</code></a>
   <em class="replaceable"><code>new-value</code></em> (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_built-in-class.html" target="_top"><code class="classname">BUILT-IN-CLASS</code></a>) <em class="replaceable"><code>object</code></em> <em class="replaceable"><code>slot</code></em>)</code></span></span></dt><dd>This method <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="slot-boundp-UC"></a>29.10.3.6. Generic Function <a class="link" href="#slot-boundp-UC" title="29.10.3.6. Generic Function CLOS:SLOT-BOUNDP-USING-CLASS"><code class="function">CLOS:SLOT-BOUNDP-USING-CLASS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#slot-boundp-UC" title="29.10.3.6. Generic Function CLOS:SLOT-BOUNDP-USING-CLASS"><code class="function">CLOS:SLOT-BOUNDP-USING-CLASS</code></a> <em class="replaceable"><code>class</code></em> <em class="replaceable"><code>object</code></em>
    <em class="replaceable"><code>slot</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>class</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a> - the class of the
    <em class="replaceable"><code>object</code></em> argument.</dd><dt><span class="term"><em class="replaceable"><code>object</code></em></span></dt><dd>an object.</dd><dt><span class="term"><em class="replaceable"><code>slot</code></em></span></dt><dd>an <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>.</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_boolean.html" target="_top"><code class="classname">BOOLEAN</code></a></dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function implements the behavior of the
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_slot-boundp.html" target="_top"><code class="function">SLOT-BOUNDP</code></a> function.  It is called by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_slot-boundp.html" target="_top"><code class="function">SLOT-BOUNDP</code></a> with the class
   of <em class="replaceable"><code>object</code></em> as its first argument and the pertinent <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> as its
   third argument.</p><p class="simpara">The generic function <a class="link" href="#slot-boundp-UC" title="29.10.3.6. Generic Function CLOS:SLOT-BOUNDP-USING-CLASS"><code class="function">CLOS:SLOT-BOUNDP-USING-CLASS</code></a> tests whether a
   specific slot in an instance is bound.</p><p class="simpara">The results are undefined if
 the <em class="replaceable"><code>class</code></em> argument is not the class of the <em class="replaceable"><code>object</code></em> argument, or
 if the <em class="replaceable"><code>slot</code></em> argument does not appear among the set of effective
 slots associated with the <em class="replaceable"><code>class</code></em> argument.</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#slot-boundp-UC" title="29.10.3.6. Generic Function CLOS:SLOT-BOUNDP-USING-CLASS"><code class="function">CLOS:SLOT-BOUNDP-USING-CLASS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>) <em class="replaceable"><code>object</code></em>
   (<em class="replaceable"><code>slot</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-EFFECTIVE-SLOT-DEFINITION</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#slot-boundp-UC" title="29.10.3.6. Generic Function CLOS:SLOT-BOUNDP-USING-CLASS"><code class="function">CLOS:SLOT-BOUNDP-USING-CLASS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>) <em class="replaceable"><code>object</code></em>
   (<em class="replaceable"><code>slot</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-EFFECTIVE-SLOT-DEFINITION</code></a>))</code></span></span></dt><dd><p class="simpara">These methods implement
 the full behavior of this generic function for slots with allocation
 <code class="constant">:INSTANCE</code> and <code class="constant">:CLASS</code>.  If the supplied slot has an allocation
 other than <code class="constant">:INSTANCE</code> or <code class="constant">:CLASS</code> an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.</p><p class="simpara">Overriding these methods is permitted,
 but may require overriding other methods in the standard implementation
 of the slot access protocol.</p></dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#slot-boundp-UC" title="29.10.3.6. Generic Function CLOS:SLOT-BOUNDP-USING-CLASS"><code class="function">CLOS:SLOT-BOUNDP-USING-CLASS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_built-in-class.html" target="_top"><code class="classname">BUILT-IN-CLASS</code></a>) <em class="replaceable"><code>object</code></em> <em class="replaceable"><code>slot</code></em>)</code></span></span></dt><dd>This method <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>.</dd></dl></div><p><strong>Remarks. </strong>In cases where the <a class="link" href="#mop-class-mo">class metaobject</a> class does not distinguish
unbound slots, true should be returned.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="slot-makunbound-UC"></a>29.10.3.7. Generic Function <a class="link" href="#slot-makunbound-UC" title="29.10.3.7. Generic Function CLOS:SLOT-MAKUNBOUND-USING-CLASS"><code class="function">CLOS:SLOT-MAKUNBOUND-USING-CLASS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#slot-makunbound-UC" title="29.10.3.7. Generic Function CLOS:SLOT-MAKUNBOUND-USING-CLASS"><code class="function">CLOS:SLOT-MAKUNBOUND-USING-CLASS</code></a> <em class="replaceable"><code>class</code></em> <em class="replaceable"><code>object</code></em>
    <em class="replaceable"><code>slot</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>class</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a> - the class of the
    <em class="replaceable"><code>object</code></em> argument.</dd><dt><span class="term"><em class="replaceable"><code>object</code></em></span></dt><dd>an object.</dd><dt><span class="term"><em class="replaceable"><code>slot</code></em></span></dt><dd>an <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a>.</dd></dl></div></dd><dt><span class="term">Value</span></dt><dd>The <em class="replaceable"><code>object</code></em> argument.</dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function implements the behavior of the
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_slot-makunbound.html" target="_top"><code class="function">SLOT-MAKUNBOUND</code></a> function.  It is called by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_slot-makunbound.html" target="_top"><code class="function">SLOT-MAKUNBOUND</code></a> with
   the class of <em class="replaceable"><code>object</code></em> as its first argument and the pertinent
   <a class="link" href="#mop-esd-mo">effective</a> <a class="link" href="#mop-slot-def-mo">slot definition metaobject</a> as its third argument.</p><p class="simpara">The generic function <a class="link" href="#slot-makunbound-UC" title="29.10.3.7. Generic Function CLOS:SLOT-MAKUNBOUND-USING-CLASS"><code class="function">CLOS:SLOT-MAKUNBOUND-USING-CLASS</code></a> restores a slot in
   an object to its unbound state.  The interpretation
   of <span class="quote">“<span class="quote">restoring a slot to its unbound state</span>”</span> depends on
   the <a class="link" href="#mop-class-mo">class metaobject</a> class.</p><p class="simpara">The results are undefined if
 the <em class="replaceable"><code>class</code></em> argument is not the class of the <em class="replaceable"><code>object</code></em> argument, or
 if the <em class="replaceable"><code>slot</code></em> argument does not appear among the set of effective
 slots associated with the <em class="replaceable"><code>class</code></em> argument.</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#slot-makunbound-UC" title="29.10.3.7. Generic Function CLOS:SLOT-MAKUNBOUND-USING-CLASS"><code class="function">CLOS:SLOT-MAKUNBOUND-USING-CLASS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>) <em class="replaceable"><code>object</code></em>
   (<em class="replaceable"><code>slot</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-EFFECTIVE-SLOT-DEFINITION</code></a>))</code></span><br /></span><span class="term"><span class="method"><code class="literal">(<a class="link" href="#slot-makunbound-UC" title="29.10.3.7. Generic Function CLOS:SLOT-MAKUNBOUND-USING-CLASS"><code class="function">CLOS:SLOT-MAKUNBOUND-USING-CLASS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>) <em class="replaceable"><code>object</code></em>
   (<em class="replaceable"><code>slot</code></em> <a class="link" href="#mop-inherit-struct" title="Table 29.1. Direct Superclass Relationships Among The Specified Metaobject Classes"><code class="classname">CLOS:STANDARD-EFFECTIVE-SLOT-DEFINITION</code></a>))</code></span></span></dt><dd><p class="simpara">These methods implement
 the full behavior of this generic function for slots with allocation
 <code class="constant">:INSTANCE</code> and <code class="constant">:CLASS</code>.  If the supplied slot has an allocation
 other than <code class="constant">:INSTANCE</code> or <code class="constant">:CLASS</code> an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.</p><p class="simpara">Overriding these methods is permitted,
 but may require overriding other methods in the standard implementation
 of the slot access protocol.</p></dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#slot-makunbound-UC" title="29.10.3.7. Generic Function CLOS:SLOT-MAKUNBOUND-USING-CLASS"><code class="function">CLOS:SLOT-MAKUNBOUND-USING-CLASS</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_built-in-class.html" target="_top"><code class="classname">BUILT-IN-CLASS</code></a>) <em class="replaceable"><code>object</code></em> <em class="replaceable"><code>slot</code></em>)</code></span></span></dt><dd>This method <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>.
</dd></dl></div></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="mop-dep-maint"></a>29.11. Dependent Maintenance</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-dep-maint-protocol">29.11.1. Protocol</a></span></dt><dd><dl><dt><span class="section"><a href="#update-dependent">29.11.1.1. Generic Function <code class="function">CLOS:UPDATE-DEPENDENT</code></a></span></dt><dt><span class="section"><a href="#add-dependent">29.11.1.2. Generic Function <code class="function">CLOS:ADD-DEPENDENT</code></a></span></dt><dt><span class="section"><a href="#remove-dependent">29.11.1.3. Generic Function <code class="function">CLOS:REMOVE-DEPENDENT</code></a></span></dt><dt><span class="section"><a href="#map-dependents">29.11.1.4. Generic Function <code class="function">CLOS:MAP-DEPENDENTS</code></a></span></dt></dl></dd></dl></div><p>It is convenient for portable metaobjects to be able to memoize
information about other metaobjects, portable or otherwise.  Because
class and <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>s can be reinitialized, and <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>s can be modified by
adding and removing methods, a means must be provided to update this
memoized information.</p><p>The dependent maintenance protocol supports this by providing a
way to register an object which should be notified whenever a class or
generic function is modified.  An object which has been registered this
way is called a <strong class="first"><em class="firstterm">dependent</em></strong> of the class or <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>.
The dependents of class and <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>s are maintained with <a class="link" href="#add-dependent" title="29.11.1.2. Generic Function CLOS:ADD-DEPENDENT"><code class="function">CLOS:ADD-DEPENDENT</code></a>
and <a class="link" href="#remove-dependent" title="29.11.1.3. Generic Function CLOS:REMOVE-DEPENDENT"><code class="function">CLOS:REMOVE-DEPENDENT</code></a>.  The dependents of a class or <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> can be
accessed with <a class="link" href="#map-dependents" title="29.11.1.4. Generic Function CLOS:MAP-DEPENDENTS"><code class="function">CLOS:MAP-DEPENDENTS</code></a>.  Dependents are notified about a
modification by calling <a class="link" href="#update-dependent" title="29.11.1.1. Generic Function CLOS:UPDATE-DEPENDENT"><code class="function">CLOS:UPDATE-DEPENDENT</code></a>.  (See the specification of
<a class="link" href="#update-dependent" title="29.11.1.1. Generic Function CLOS:UPDATE-DEPENDENT"><code class="function">CLOS:UPDATE-DEPENDENT</code></a> for detailed description of the circumstances under
which it is called.)</p><p>To prevent conflicts between two portable programs, or between
portable programs and the implementation, portable code must not
register metaobjects themselves as dependents. Instead, portable
programs which need to record a metaobject as a dependent, should
encapsulate that metaobject in some other kind of object, and record
that object as the dependent.  The results are undefined if this
restriction is violated.</p><div class="informalexample"><a id="mop-dep-maint-ex"></a><p>This example shows a general facility for encapsulating
metaobjects before recording them as dependents.  The facility defines a
basic kind of encapsulating object: an updater.  Specializations of the
basic class can be defined with appropriate special updating behavior.
In this way, information about the updating required is associated with
each updater rather than with the metaobject being updated.</p><p>Updaters are used to encapsulate any metaobject which requires
updating when a given class or generic function is modified.  The
function <code class="function">record-updater</code> is called to both create an
updater and add it to the dependents of the class or generic function.
Methods on the generic function <a class="link" href="#update-dependent" title="29.11.1.1. Generic Function CLOS:UPDATE-DEPENDENT"><code class="function">CLOS:UPDATE-DEPENDENT</code></a>, specialized to the
specific class of updater do the appropriate update work.</p><pre class="programlisting">
(defclass updater ()
  ((dependent :initarg :dependent :reader dependent)))

(defun record-updater (class dependee dependent <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> initargs)
  (let ((updater (apply #'make-instance class :dependent dependent
                                              initargs)))
    (add-dependent dependee updater)
    updater))
</pre><p>A <code class="function">flush-cache-updater</code> simply flushes the
cache of the dependent when it is updated.</p><pre class="programlisting">
(defclass flush-cache-updater (updater) ())

(defmethod update-dependent (dependee (updater flush-cache-updater) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> args)
  (declare (ignore args))
  (flush-cache (dependent updater)))
</pre></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-dep-maint-protocol"></a>29.11.1. Protocol</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#update-dependent">29.11.1.1. Generic Function <code class="function">CLOS:UPDATE-DEPENDENT</code></a></span></dt><dt><span class="section"><a href="#add-dependent">29.11.1.2. Generic Function <code class="function">CLOS:ADD-DEPENDENT</code></a></span></dt><dt><span class="section"><a href="#remove-dependent">29.11.1.3. Generic Function <code class="function">CLOS:REMOVE-DEPENDENT</code></a></span></dt><dt><span class="section"><a href="#map-dependents">29.11.1.4. Generic Function <code class="function">CLOS:MAP-DEPENDENTS</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="update-dependent"></a>29.11.1.1. Generic Function <a class="link" href="#update-dependent" title="29.11.1.1. Generic Function CLOS:UPDATE-DEPENDENT"><code class="function">CLOS:UPDATE-DEPENDENT</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#update-dependent" title="29.11.1.1. Generic Function CLOS:UPDATE-DEPENDENT"><code class="function">CLOS:UPDATE-DEPENDENT</code></a> <em class="replaceable"><code>metaobject</code></em>
    <em class="replaceable"><code>dependent</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>initargs</code></em>)
</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>metaobject</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a> or a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a> - the metaobject being
      reinitialized or otherwise modified.</dd><dt><span class="term"><em class="replaceable"><code>dependent</code></em></span></dt><dd>an object - the dependent being updated.
   </dd><dt><span class="term"><em class="replaceable"><code>initargs</code></em></span></dt><dd>a list of the initialization arguments for
      the metaobject redefinition.</dd></dl></div></dd><dt><span class="term">Values</span></dt><dd>The values returned by this generic function are unspecified.
 </dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function is called to update a
   dependent of <em class="replaceable"><code>metaobject</code></em>.</p><p class="simpara">When a class or a generic function is reinitialized each of
   its dependents is updated.  The <em class="replaceable"><code>initargs</code></em> argument to
   <a class="link" href="#update-dependent" title="29.11.1.1. Generic Function CLOS:UPDATE-DEPENDENT"><code class="function">CLOS:UPDATE-DEPENDENT</code></a> is the set of initialization arguments received by
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_rei_ize-instance.html" target="_top"><code class="function">REINITIALIZE-INSTANCE</code></a>.</p><p class="simpara">When a method is added to a generic function, each of the
   generic function's dependents is updated.  The <em class="replaceable"><code>initargs</code></em> argument
   is a list of two elements: the symbol <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_add-method.html" target="_top"><code class="function">ADD-METHOD</code></a>, and the method
   that was added.</p><p class="simpara">When a method is removed from a generic function, each of the
   generic function's dependents is updated.  The <em class="replaceable"><code>initargs</code></em> argument
   is a list of two elements: the symbol <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_remove-method.html" target="_top"><code class="function">REMOVE-METHOD</code></a>, and the method
   that was removed.</p><p>In each case, <a class="link" href="#map-dependents" title="29.11.1.4. Generic Function CLOS:MAP-DEPENDENTS"><code class="function">CLOS:MAP-DEPENDENTS</code></a> is used to call
   <a class="link" href="#update-dependent" title="29.11.1.1. Generic Function CLOS:UPDATE-DEPENDENT"><code class="function">CLOS:UPDATE-DEPENDENT</code></a> on each of the dependents.  So, for example, the
   update of a generic function's dependents when a method is added
   could be performed by the following code:</p><pre class="programlisting">
(<a class="link" href="#map-dependents" title="29.11.1.4. Generic Function CLOS:MAP-DEPENDENTS"><code class="function">CLOS:MAP-DEPENDENTS</code></a> <em class="replaceable"><code>generic-function</code></em>
                     #'(lambda (dep)
                         (<a class="link" href="#update-dependent" title="29.11.1.1. Generic Function CLOS:UPDATE-DEPENDENT"><code class="function">CLOS:UPDATE-DEPENDENT</code></a> <em class="replaceable"><code>generic-function</code></em>
                                                dep 'add-method new-method)))
</pre></dd></dl></div><p><strong>Remarks. </strong>See <a class="xref" href="#mop-dep-maint" title="29.11. Dependent Maintenance">Section 29.11, “Dependent Maintenance”</a> for remarks about the
  use of this facility.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="add-dependent"></a>29.11.1.2. Generic Function <a class="link" href="#add-dependent" title="29.11.1.2. Generic Function CLOS:ADD-DEPENDENT"><code class="function">CLOS:ADD-DEPENDENT</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#add-dependent" title="29.11.1.2. Generic Function CLOS:ADD-DEPENDENT"><code class="function">CLOS:ADD-DEPENDENT</code></a> <em class="replaceable"><code>metaobject</code></em>
    <em class="replaceable"><code>dependent</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>metaobject</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a> or a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>dependent</code></em></span></dt><dd>an object.</dd></dl></div></dd><dt><span class="term">Values</span></dt><dd>The values returned by this generic function are unspecified.
 </dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function adds <em class="replaceable"><code>dependent</code></em> to the
   dependents of <em class="replaceable"><code>metaobject</code></em>.  If <em class="replaceable"><code>dependent</code></em> is already in the set
   of dependents it is not added again (no <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed).</p><p class="simpara">The generic function <a class="link" href="#map-dependents" title="29.11.1.4. Generic Function CLOS:MAP-DEPENDENTS"><code class="function">CLOS:MAP-DEPENDENTS</code></a> can be called to access
   the set of dependents of a class or generic function.  The generic
   function <a class="link" href="#remove-dependent" title="29.11.1.3. Generic Function CLOS:REMOVE-DEPENDENT"><code class="function">CLOS:REMOVE-DEPENDENT</code></a> can be called to remove an object from
   the set of dependents of a class or generic function.  The effect of
   calling <a class="link" href="#add-dependent" title="29.11.1.2. Generic Function CLOS:ADD-DEPENDENT"><code class="function">CLOS:ADD-DEPENDENT</code></a> or <a class="link" href="#remove-dependent" title="29.11.1.3. Generic Function CLOS:REMOVE-DEPENDENT"><code class="function">CLOS:REMOVE-DEPENDENT</code></a> while a call to
   <a class="link" href="#map-dependents" title="29.11.1.4. Generic Function CLOS:MAP-DEPENDENTS"><code class="function">CLOS:MAP-DEPENDENTS</code></a> on the same class or generic function is in progress
   is unspecified.</p><p class="simpara">The situations in which <a class="link" href="#add-dependent" title="29.11.1.2. Generic Function CLOS:ADD-DEPENDENT"><code class="function">CLOS:ADD-DEPENDENT</code></a> is called are not
   specified.</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#add-dependent" title="29.11.1.2. Generic Function CLOS:ADD-DEPENDENT"><code class="function">CLOS:ADD-DEPENDENT</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>) <em class="replaceable"><code>dependent</code></em>)</code></span></span></dt><dd><p class="simpara">No behavior is specified for this
   method beyond that which is specified for the generic function.</p><p>This method cannot be overridden unless the
 following methods are overridden as well:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#remove-dependent" title="29.11.1.3. Generic Function CLOS:REMOVE-DEPENDENT"><code class="function">CLOS:REMOVE-DEPENDENT</code></a>
       (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</code></span></li><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#map-dependents" title="29.11.1.4. Generic Function CLOS:MAP-DEPENDENTS"><code class="function">CLOS:MAP-DEPENDENTS</code></a>
       (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</code></span></li></ul></div></dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#add-dependent" title="29.11.1.2. Generic Function CLOS:ADD-DEPENDENT"><code class="function">CLOS:ADD-DEPENDENT</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>) <em class="replaceable"><code>dependent</code></em>)</code></span></span></dt><dd><p class="simpara">No behavior is specified for this
   method beyond that which is specified for the generic function.</p><p>This method cannot be overridden unless the
 following methods are overridden as well:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#remove-dependent" title="29.11.1.3. Generic Function CLOS:REMOVE-DEPENDENT"><code class="function">CLOS:REMOVE-DEPENDENT</code></a>
       (<a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</code></span></li><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#map-dependents" title="29.11.1.4. Generic Function CLOS:MAP-DEPENDENTS"><code class="function">CLOS:MAP-DEPENDENTS</code></a>
       (<a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</code></span></li></ul></div></dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#add-dependent" title="29.11.1.2. Generic Function CLOS:ADD-DEPENDENT"><code class="function">CLOS:ADD-DEPENDENT</code></a>
   (<em class="replaceable"><code>generic-function</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>) <em class="replaceable"><code>dependent</code></em>)</code></span></span></dt><dd><p class="simpara">No behavior is specified for this
   method beyond that which is specified for the generic function.</p><p>This method cannot be overridden unless the
 following methods are overridden as well:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#remove-dependent" title="29.11.1.3. Generic Function CLOS:REMOVE-DEPENDENT"><code class="function">CLOS:REMOVE-DEPENDENT</code></a>
       (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</code></span></li><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#map-dependents" title="29.11.1.4. Generic Function CLOS:MAP-DEPENDENTS"><code class="function">CLOS:MAP-DEPENDENTS</code></a>
       (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</code></span></li></ul></div></dd></dl></div><p><strong>Remarks. </strong>See <a class="xref" href="#mop-dep-maint" title="29.11. Dependent Maintenance">Section 29.11, “Dependent Maintenance”</a> for remarks about the
  use of this facility.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="remove-dependent"></a>29.11.1.3. Generic Function <a class="link" href="#remove-dependent" title="29.11.1.3. Generic Function CLOS:REMOVE-DEPENDENT"><code class="function">CLOS:REMOVE-DEPENDENT</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#remove-dependent" title="29.11.1.3. Generic Function CLOS:REMOVE-DEPENDENT"><code class="function">CLOS:REMOVE-DEPENDENT</code></a> <em class="replaceable"><code>metaobject</code></em>
     <em class="replaceable"><code>dependent</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>metaobject</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a> or a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>dependent</code></em></span></dt><dd>an object.</dd></dl></div></dd><dt><span class="term">Values</span></dt><dd>The values returned by this generic function are unspecified.
 </dd><dt><span class="term">Purpose</span></dt><dd><p class="simpara">This generic function removes <em class="replaceable"><code>dependent</code></em> from the
   dependents of <em class="replaceable"><code>metaobject</code></em>.  If <em class="replaceable"><code>dependent</code></em> is not one of the
   dependents of <em class="replaceable"><code>metaobject</code></em>, no <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.</p><p class="simpara">The generic function <a class="link" href="#map-dependents" title="29.11.1.4. Generic Function CLOS:MAP-DEPENDENTS"><code class="function">CLOS:MAP-DEPENDENTS</code></a> can be called to access
   the set of dependents of a class or generic function.  The generic
   function <a class="link" href="#add-dependent" title="29.11.1.2. Generic Function CLOS:ADD-DEPENDENT"><code class="function">CLOS:ADD-DEPENDENT</code></a> can be called to add an object from the set
   of dependents of a class or generic function.  The effect of calling
   <a class="link" href="#add-dependent" title="29.11.1.2. Generic Function CLOS:ADD-DEPENDENT"><code class="function">CLOS:ADD-DEPENDENT</code></a> or <a class="link" href="#remove-dependent" title="29.11.1.3. Generic Function CLOS:REMOVE-DEPENDENT"><code class="function">CLOS:REMOVE-DEPENDENT</code></a> while a call to
   <a class="link" href="#map-dependents" title="29.11.1.4. Generic Function CLOS:MAP-DEPENDENTS"><code class="function">CLOS:MAP-DEPENDENTS</code></a> on the same class or generic function is in progress
   is unspecified.</p><p class="simpara">The situations in which <a class="link" href="#remove-dependent" title="29.11.1.3. Generic Function CLOS:REMOVE-DEPENDENT"><code class="function">CLOS:REMOVE-DEPENDENT</code></a> is called are not
   specified.</p></dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#remove-dependent" title="29.11.1.3. Generic Function CLOS:REMOVE-DEPENDENT"><code class="function">CLOS:REMOVE-DEPENDENT</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>) <em class="replaceable"><code>dependent</code></em>)</code></span></span></dt><dd><p class="simpara">No behavior is specified for this
   method beyond that which is specified for the generic function.</p><p>This method cannot be overridden unless the
 following methods are overridden as well:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#add-dependent" title="29.11.1.2. Generic Function CLOS:ADD-DEPENDENT"><code class="function">CLOS:ADD-DEPENDENT</code></a>
       (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</code></span></li><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#map-dependents" title="29.11.1.4. Generic Function CLOS:MAP-DEPENDENTS"><code class="function">CLOS:MAP-DEPENDENTS</code></a>
       (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</code></span></li></ul></div></dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#remove-dependent" title="29.11.1.3. Generic Function CLOS:REMOVE-DEPENDENT"><code class="function">CLOS:REMOVE-DEPENDENT</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>) <em class="replaceable"><code>dependent</code></em>)</code></span></span></dt><dd><p class="simpara">No behavior is specified for this
   method beyond that which is specified for the generic function.</p><p>This method cannot be overridden unless the
 following methods are overridden as well:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#add-dependent" title="29.11.1.2. Generic Function CLOS:ADD-DEPENDENT"><code class="function">CLOS:ADD-DEPENDENT</code></a>
       (<a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</code></span></li><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#map-dependents" title="29.11.1.4. Generic Function CLOS:MAP-DEPENDENTS"><code class="function">CLOS:MAP-DEPENDENTS</code></a>
       (<a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</code></span></li></ul></div></dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#remove-dependent" title="29.11.1.3. Generic Function CLOS:REMOVE-DEPENDENT"><code class="function">CLOS:REMOVE-DEPENDENT</code></a>
   (<em class="replaceable"><code>class</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>) <em class="replaceable"><code>dependent</code></em>)</code></span></span></dt><dd><p class="simpara">No behavior is specified for this
   method beyond that which is specified for the generic function.</p><p>This method cannot be overridden unless the
 following methods are overridden as well:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#add-dependent" title="29.11.1.2. Generic Function CLOS:ADD-DEPENDENT"><code class="function">CLOS:ADD-DEPENDENT</code></a>
       (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</code></span></li><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#map-dependents" title="29.11.1.4. Generic Function CLOS:MAP-DEPENDENTS"><code class="function">CLOS:MAP-DEPENDENTS</code></a>
       (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</code></span></li></ul></div></dd></dl></div><p><strong>Remarks. </strong>See <a class="xref" href="#mop-dep-maint" title="29.11. Dependent Maintenance">Section 29.11, “Dependent Maintenance”</a> for remarks about the
  use of this facility.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="map-dependents"></a>29.11.1.4. Generic Function <a class="link" href="#map-dependents" title="29.11.1.4. Generic Function CLOS:MAP-DEPENDENTS"><code class="function">CLOS:MAP-DEPENDENTS</code></a></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">Syntax</span></dt><dd><code class="code">(<a class="link" href="#map-dependents" title="29.11.1.4. Generic Function CLOS:MAP-DEPENDENTS"><code class="function">CLOS:MAP-DEPENDENTS</code></a> <em class="replaceable"><code>metaobject</code></em>
    <em class="replaceable"><code>function</code></em>)</code></dd><dt><span class="term">Arguments</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>metaobject</code></em></span></dt><dd>a <a class="link" href="#mop-class-mo">class metaobject</a> or a <a class="link" href="#mop-gen-fun-mo">generic function metaobject</a>.</dd><dt><span class="term"><em class="replaceable"><code>function</code></em></span></dt><dd>a function which accepts one argument.
</dd></dl></div></dd><dt><span class="term">Values</span></dt><dd>The values returned by this generic function are unspecified.
 </dd><dt><span class="term">Purpose</span></dt><dd>This generic function applies <em class="replaceable"><code>function</code></em> to each of
   the dependents of <em class="replaceable"><code>metaobject</code></em>.  The order in which the dependents
   are processed is not specified, but <em class="replaceable"><code>function</code></em> is applied to each
   dependent once and only once.  If, during the mapping,
   <a class="link" href="#add-dependent" title="29.11.1.2. Generic Function CLOS:ADD-DEPENDENT"><code class="function">CLOS:ADD-DEPENDENT</code></a> or <a class="link" href="#remove-dependent" title="29.11.1.3. Generic Function CLOS:REMOVE-DEPENDENT"><code class="function">CLOS:REMOVE-DEPENDENT</code></a> is called to alter the
   dependents of <em class="replaceable"><code>metaobject</code></em>, it is not specified whether the newly
   added or removed dependent will have <em class="replaceable"><code>function</code></em> applied to it.
</dd></dl></div><div class="variablelist"><p class="title"><strong>Methods</strong></p><dl class="variablelist"><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#map-dependents" title="29.11.1.4. Generic Function CLOS:MAP-DEPENDENTS"><code class="function">CLOS:MAP-DEPENDENTS</code></a>
   (<em class="replaceable"><code>metaobject</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>) <em class="replaceable"><code>function</code></em>)</code></span></span></dt><dd><p class="simpara">No behavior is specified for this
   method beyond that which is specified for the generic function.</p><p>This method cannot be overridden unless the
 following methods are overridden as well:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#add-dependent" title="29.11.1.2. Generic Function CLOS:ADD-DEPENDENT"><code class="function">CLOS:ADD-DEPENDENT</code></a>
       (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</code></span></li><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#remove-dependent" title="29.11.1.3. Generic Function CLOS:REMOVE-DEPENDENT"><code class="function">CLOS:REMOVE-DEPENDENT</code></a>
       (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</code></span></li></ul></div></dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#map-dependents" title="29.11.1.4. Generic Function CLOS:MAP-DEPENDENTS"><code class="function">CLOS:MAP-DEPENDENTS</code></a>
   (<em class="replaceable"><code>metaobject</code></em> <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>) <em class="replaceable"><code>function</code></em>)</code></span></span></dt><dd><p class="simpara">No behavior is specified for this
   method beyond that which is specified for the generic function.</p><p>This method cannot be overridden unless the
 following methods are overridden as well:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#add-dependent" title="29.11.1.2. Generic Function CLOS:ADD-DEPENDENT"><code class="function">CLOS:ADD-DEPENDENT</code></a>
       (<a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</code></span></li><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#remove-dependent" title="29.11.1.3. Generic Function CLOS:REMOVE-DEPENDENT"><code class="function">CLOS:REMOVE-DEPENDENT</code></a>
       (<a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</code></span></li></ul></div></dd><dt><span class="term"><span class="method"><code class="literal">(<a class="link" href="#map-dependents" title="29.11.1.4. Generic Function CLOS:MAP-DEPENDENTS"><code class="function">CLOS:MAP-DEPENDENTS</code></a>
   (<em class="replaceable"><code>metaobject</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a>) <em class="replaceable"><code>function</code></em>)</code></span></span></dt><dd><p class="simpara">No behavior is specified for this
   method beyond that which is specified for the generic function.</p><p>This method cannot be overridden unless the
 following methods are overridden as well:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#add-dependent" title="29.11.1.2. Generic Function CLOS:ADD-DEPENDENT"><code class="function">CLOS:ADD-DEPENDENT</code></a>
       (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</code></span></li><li class="listitem"><span class="method"><code class="literal"><a class="link" href="#remove-dependent" title="29.11.1.3. Generic Function CLOS:REMOVE-DEPENDENT"><code class="function">CLOS:REMOVE-DEPENDENT</code></a>
       (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standa_ric-function.html" target="_top"><code class="classname">STANDARD-GENERIC-FUNCTION</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_t.html" target="_top"><code class="classname">T</code></a>)</code></span></li></ul></div></dd></dl></div><p><strong>Remarks. </strong>See <a class="xref" href="#mop-dep-maint" title="29.11. Dependent Maintenance">Section 29.11, “Dependent Maintenance”</a> for remarks about the
  use of this facility.</p></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="mop-clisp"></a>29.12. Deviations from [<span class="citation"><a class="link" href="#amop" title="The Art of the Metaobject Protocol">AMOP</a></span>]</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-clisp-warn">29.12.1. Warning <code class="classname">CLOS:CLOS-WARNING</code></a></span></dt><dd><dl><dt><span class="section"><a href="#mop-clisp-gf-already-called-warning">29.12.1.1. Warning   <code class="classname">CLOS:GF-ALREADY-CALLED-WARNING</code></a></span></dt><dt><span class="section"><a href="#mop-clisp-gf-replacing-method-warning">29.12.1.2. Warning   <code class="classname">CLOS:GF-REPLACING-METHOD-WARNING</code></a></span></dt><dt><span class="section"><a href="#class-obsolescence-warning">29.12.1.3. Warning   <code class="classname">CLOS:CLASS-OBSOLESCENCE-WARNING</code></a></span></dt></dl></dd></dl></div><p>This section lists the differences between the [<span class="citation"><a class="link" href="#amop" title="The Art of the Metaobject Protocol">AMOP</a></span>] and the
<a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> implementation thereof.</p><div class="itemizedlist"><a id="mop-not-in-clisp"></a><p class="title"><strong>Not implemented in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a></strong></p><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>The generic function <a class="link" href="#make-method-lambda" title="29.5.4.10. Generic Function CLOS:MAKE-METHOD-LAMBDA"><code class="function">CLOS:MAKE-METHOD-LAMBDA</code></a> is not implemented.
  See <a class="xref" href="#mop-gf-invocation" title="29.5.3.2. Generic Function Invocation Protocol">Section 29.5.3.2, “Generic Function Invocation Protocol”</a>.</p></li></ul></div><div class="itemizedlist"><a id="mop-clisp-different"></a><p class="title"><strong>Features implemented differently in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a></strong></p><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>The class precedence list of <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-OBJECT</code></a>
  is different. See <a class="xref" href="#mop-mo-cl-inheritance" title="29.2.2. Inheritance Structure of Metaobject Classes">Section 29.2.2, “Inheritance Structure of Metaobject Classes”</a>.</p></li><li class="listitem"><p>The <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> macro passes default values to <a class="link" href="#ensure-class" title="29.3.6.2. Generic Function CLOS:ENSURE-CLASS"><code class="function">CLOS:ENSURE-CLASS</code></a>.
  See <a class="xref" href="#mop-cl-defclass" title="29.3.1. Macro DEFCLASS">Section 29.3.1, “Macro <code class="function">DEFCLASS</code>”</a>.</p></li><li class="listitem"><p>The <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a> macro passes default values to <a class="link" href="#ensure-gf" title="29.5.4.2. Generic Function ENSURE-GENERIC-FUNCTION"><code class="function">ENSURE-GENERIC-FUNCTION</code></a>.
  See <a class="xref" href="#mop-gf-init-defgeneric" title="29.5.3.1. Macro DEFGENERIC">Section 29.5.3.1, “Macro <code class="function">DEFGENERIC</code>”</a>.</p></li><li class="listitem"><p>The class <a class="link" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP"><code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code></a> is implemented differently.
  See <a class="xref" href="#forward-referenced-class-clisp" title="Implementation of class CLOS:FORWARD-REFERENCED-CLASS in CLISP">Implementation of class <code class="classname">CLOS:FORWARD-REFERENCED-CLASS</code> in <span class="command"><strong>CLISP</strong></span></a>.</p></li><li class="listitem"><p>The function <a class="link" href="#gf-argument-precedence-order" title="29.5.2.4. Generic Function CLOS:GENERIC-FUNCTION-ARGUMENT-PRECEDENCE-ORDER"><code class="function">CLOS:GENERIC-FUNCTION-ARGUMENT-PRECEDENCE-ORDER</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>
  if the generic function has no <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a>.</p></li><li class="listitem"><p>It is not possible to create a class with metaclass
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a> when specifying a superclass with metaclass
  <a class="link" href="#mop-sa-funcallable" title="29.10.2. Funcallable Instances"><code class="classname">CLOS:FUNCALLABLE-STANDARD-CLASS</code></a>, even though <a class="link" href="#validate-superclass" title="29.3.6.7. Generic Function CLOS:VALIDATE-SUPERCLASS"><code class="function">CLOS:VALIDATE-SUPERCLASS</code></a>
  returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> for this situation.
  
</p></li></ul></div><div class="itemizedlist"><a id="mop-clisp-ext"></a><p class="title"><strong>Extensions specific to <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a></strong></p><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>The <a class="link" href="#mop-chap" title="Chapter 29. Meta-Object Protocol">Meta-Object Protocol</a> is applicable to classes of type <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_structure-class.html" target="_top"><code class="classname">STRUCTURE-CLASS</code></a>.
  The default superclass for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_structure-class.html" target="_top"><code class="classname">STRUCTURE-CLASS</code></a> instances is
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_structure-object.html" target="_top"><code class="classname">STRUCTURE-OBJECT</code></a>.
  Structure classes do not support multiple inheritance and reinitialization.
  See <a class="xref" href="#mop-cl-init-mo" title="29.3.5.1. Initialization of class metaobjects">Section 29.3.5.1, “Initialization of class metaobjects”</a>.
  See also <a class="xref" href="#defstruct-mop" title="8.2. The structure Meta-Object Protocol">Section 8.2, “The structure Meta-Object Protocol”</a>.</p></li><li class="listitem"><p>The <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a> macro supports user-defined options.
  See <a class="xref" href="#mop-defgeneric-user-options" title="User-defined options">User-defined options</a>.</p></li><li class="listitem"><p>The class <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a> is subclassable.
  See <a class="xref" href="#mop-mo-cl-inheritance" title="29.2.2. Inheritance Structure of Metaobject Classes">Section 29.2.2, “Inheritance Structure of Metaobject Classes”</a>.</p></li><li class="listitem"><p>Slot names like <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> are allowed.
  See <a class="xref" href="#slotdef-name" title="29.4.2.1.1. Generic Function CLOS:SLOT-DEFINITION-NAME">Section 29.4.2.1.1, “Generic Function <code class="function">CLOS:SLOT-DEFINITION-NAME</code>”</a>.</p></li><li class="listitem"><p>The <a class="link" href="#validate-superclass" title="29.3.6.7. Generic Function CLOS:VALIDATE-SUPERCLASS"><code class="function">CLOS:VALIDATE-SUPERCLASS</code></a> method is more permissive by
  default and does not need to be overridden in
  some <span class="quote">“<span class="quote">obvious</span>”</span> cases.
  See <a class="xref" href="#validate-superclass" title="29.3.6.7. Generic Function CLOS:VALIDATE-SUPERCLASS">Section 29.3.6.7, “Generic Function <code class="function">CLOS:VALIDATE-SUPERCLASS</code>”</a>.</p></li><li class="listitem"><p>New generic function <a class="link" href="#compute-dsd-initargs" title="29.3.6.8. Generic Function CLOS:COMPUTE-DIRECT-SLOT-DEFINITION-INITARGS"><code class="function">CLOS:COMPUTE-DIRECT-SLOT-DEFINITION-INITARGS</code></a>.  It can sometimes
  be used when overriding <a class="link" href="#dsd-class" title="29.3.6.9. Generic Function CLOS:DIRECT-SLOT-DEFINITION-CLASS"><code class="function">CLOS:DIRECT-SLOT-DEFINITION-CLASS</code></a> is cumbersome.</p></li><li class="listitem"><p>New generic function <a class="link" href="#compute-esd-initargs" title="29.3.6.13. Generic Function CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION-INITARGS"><code class="function">CLOS:COMPUTE-EFFECTIVE-SLOT-DEFINITION-INITARGS</code></a>. It can sometimes
  be used when overriding <a class="link" href="#esd-class" title="29.3.6.14. Generic Function CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS"><code class="function">CLOS:EFFECTIVE-SLOT-DEFINITION-CLASS</code></a> is cumbersome.</p></li><li class="listitem"><p>New function <a class="link" href="#compute-effective-method-as-function" title="29.5.4.9. Function CLOS:COMPUTE-EFFECTIVE-METHOD-AS-FUNCTION"><code class="function">CLOS:COMPUTE-EFFECTIVE-METHOD-AS-FUNCTION</code></a>. It
  can be used in overriding methods of <a class="link" href="#compute-discriminating-function" title="29.5.4.11. Generic Function CLOS:COMPUTE-DISCRIMINATING-FUNCTION"><code class="function">CLOS:COMPUTE-DISCRIMINATING-FUNCTION</code></a>.
</p></li><li class="listitem"><p>The generic function <a class="link" href="#ensure-gf-UC" title="29.5.4.3. Generic Function CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS"><code class="function">CLOS:ENSURE-GENERIC-FUNCTION-USING-CLASS</code></a> accepts a
  <code class="constant">:DECLARE</code> keyword.</p></li><li class="listitem"><p>The functions <a class="link" href="#funcallable-standard-instance-access" title="29.10.3.2. Function CLOS:FUNCALLABLE-STANDARD-INSTANCE-ACCESS"><code class="function">CLOS:FUNCALLABLE-STANDARD-INSTANCE-ACCESS</code></a> and
  <a class="link" href="#standard-instance-access" title="29.10.3.1. Function CLOS:STANDARD-INSTANCE-ACCESS"><code class="function">CLOS:STANDARD-INSTANCE-ACCESS</code></a> support non-updated obsolete instances and
  also support slots with allocation <code class="constant">:CLASS</code>.</p></li><li class="listitem"><p>The existence of the function <a class="link" href="#class-direct-subclasses" title="29.3.3.6. Generic Function CLOS:CLASS-DIRECT-SUBCLASSES"><code class="function">CLOS:CLASS-DIRECT-SUBCLASSES</code></a>
  does not prevent otherwise unreferenced classes from being <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed.
</p></li></ul></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mop-clisp-warn"></a>29.12.1. Warning <code class="classname">CLOS:CLOS-WARNING</code></h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mop-clisp-gf-already-called-warning">29.12.1.1. Warning   <code class="classname">CLOS:GF-ALREADY-CALLED-WARNING</code></a></span></dt><dt><span class="section"><a href="#mop-clisp-gf-replacing-method-warning">29.12.1.2. Warning   <code class="classname">CLOS:GF-REPLACING-METHOD-WARNING</code></a></span></dt><dt><span class="section"><a href="#class-obsolescence-warning">29.12.1.3. Warning   <code class="classname">CLOS:CLASS-OBSOLESCENCE-WARNING</code></a></span></dt></dl></div><p>When <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> encounters suspicious or suboptimal <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> code,
 it issues a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_warning.html" target="_top"><code class="classname">WARNING</code></a> of type <code class="classname">CLOS:CLOS-WARNING</code>
 or a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_style-warning.html" target="_top"><code class="classname">STYLE-WARNING</code></a> of type <code class="classname">CLOS:CLOS-STYLE-WARNING</code>.
 To suppress the undesired warnings (<span class="strong"><strong>not</strong></span> recommended!) use
 <a href="impnotes.html#global-handler" class="olink"><code class="function">EXT:SET-GLOBAL-HANDLER</code></a> with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_abortcm_c_cm_use-value.html" target="_top"><code class="function">MUFFLE-WARNING</code></a> on the appropriate
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_warning.html" target="_top"><code class="classname">WARNING</code></a> type;.
 To find where the warnings come from (recommended), set
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stbreak-on-signalsst.html" target="_top"><code class="varname">*BREAK-ON-SIGNALS*</code></a> to the appropriate <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_warning.html" target="_top"><code class="classname">WARNING</code></a> type.</p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-clisp-gf-already-called-warning"></a>29.12.1.1. Warning
  <code class="classname">CLOS:GF-ALREADY-CALLED-WARNING</code></h4></div></div></div><p>This is a hint that the order in which program files are loaded
 (order of definitions, order of macro expansions, or similar) may be wrong.
Example:<a id="mop-clisp-gf-already-called-warning-code"></a></p><pre class="programlisting">
(defclass ware () ((title :initarg :title :accessor title)))
(defclass book (ware) ())
(defclass compact-disk (ware) ())
(defclass dvd (ware) ())
(defgeneric add-to-inventory (object))
(defmethod add-to-inventory ((object ware)) nil)
(add-to-inventory (make-instance 'book :title "CLtL1"))
(defvar *book-counter* 0)
(defmethod add-to-inventory ((object book)) (incf *book-counter*))
(add-to-inventory (make-instance 'book :title "CLtL2"))
*book-counter*
⇒ <code class="computeroutput">1</code>
</pre><p>
 Since <a class="xref" href="#CLtL1" title="Common Lisp: the Language (1st Edition)">[<abbr class="abbrev">CLtL1</abbr>]</a> and <a class="xref" href="#CLtL2" title="Common Lisp: the Language (2nd Edition)">[<abbr class="abbrev">CLtL2</abbr>]</a> were already added to the inventory, the
 programmer might have expected that <code class="varname">*book-counter*</code>
 is 2.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">No warning for standard generic functions</h3><p>A few functions, such as <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_print-object.html" target="_top"><code class="function">PRINT-OBJECT</code></a>, are listed in the
  [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] and the [<span class="citation"><a class="link" href="#amop" title="The Art of the Metaobject Protocol">AMOP</a></span>] as <span class="quote">“<span class="quote">standard generic functions</span>”</span>,
  to which users may add methods.
  This warning is <span class="strong"><strong>not</strong></span> issued for such functions.</p></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">This is a <code class="classname">STYLE-WARNING</code></h3><p>This warning is actually a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_style-warning.html" target="_top"><code class="classname">STYLE-WARNING</code></a> because it indicates the
  behavior officially sanctioned by the standard and useful in some situations.
  We only warn on it because it <span class="emphasis"><em>may</em></span> lead to confusing
  behavior for inexperienced users.</p></div><div class="simplesect"><div class="titlepage"><div><div><h5 class="title"><a id="mop-clisp-gf-already-called-warning-motivation"></a>Motivation</h5></div></div></div><p>A generic function is defined by a contract.
  Whoever adds a method to a generic function, however, also
  expects the contract to be fulfilled.
  (In the example above, the contract is that
  <code class="varname">*book-counter*</code> equals the number of invocations
  of <code class="function">add-to-inventory</code> on
  <code class="classname">book</code> instances.)
  If the generic function has already been called before the
  method was added, the method's contract is definitely broken.
  Maybe the programmer has foreseen this case (in this example:
  he could initialize <code class="varname">*book-counter*</code> to the number of
  instances of <code class="classname">book</code> that exist at this moment,
  rather than to <code class="literal">0</code>), or maybe not. This is what the warning is about.
</p></div><div class="simplesect"><div class="titlepage"><div><div><h5 class="title"><a id="mop-clisp-gf-dynamically-modifiable"></a>Disabling
the warning for a specific generic function</h5></div></div></div><p>If your generic function constitutes a public interface which is
used by adding methods (similar to aforementioned <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_print-object.html" target="_top"><code class="function">PRINT-OBJECT</code></a>), you
can declare it as such:</p><pre class="programlisting">
(defgeneric my-public-gf (a b c)
  (declare (clos:dynamically-modifiable))
  ...)</pre><p>
</p></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mop-clisp-gf-replacing-method-warning"></a>29.12.1.2. Warning
  <code class="classname">CLOS:GF-REPLACING-METHOD-WARNING</code></h4></div></div></div><p>This is a hint that different parts of the program, possibly
 developed by independent people, are colliding.
Example: in addition to the code
 <a class="link" href="#mop-clisp-gf-already-called-warning-code">above</a>:
 </p><pre class="programlisting">
(defvar *book-sales-statistics* (make-hash-table :test 'equal))
(defmethod add-to-inventory ((object book))
  (setf (gethash (title object) sale-stats) (cons 0 0)))
(add-to-inventory (make-instance 'book :title "AMOP"))
*book-counter*
⇒ <code class="computeroutput">1</code>
*book-sales-statistics*
⇒ <code class="computeroutput">#S(HASH-TABLE :TEST FASTHASH-EQUAL ("AMOP" . (0 . 0)))</code>
</pre><p>
The programmer who programmed the first
 <span class="method"><code class="literal"><code class="function">add-to-inventory</code>@<code class="classname">book</code></code></span>
 method expects that <code class="varname">*book-counter*</code> will be incremented.
 The programmer who programmed the second
 <span class="method"><code class="literal"><code class="function">add-to-inventory</code>@<code class="classname">book</code></code></span>
 method expects that <code class="varname">*book-sales-statistics*</code> gets
 augmented.  If the implementation gives no warning, one of the two
 programmers will waste time debugging.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">This is a <code class="classname">STYLE-WARNING</code></h3><p>This warning is actually a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_style-warning.html" target="_top"><code class="classname">STYLE-WARNING</code></a> because it indicates the
  behavior officially sanctioned by the standard and useful in some situations.
  We only warn on it because it <span class="emphasis"><em>may</em></span> lead to confusing
  behavior for inexperienced users.</p></div><div class="simplesect"><div class="titlepage"><div><div><h5 class="title"><a id="mop-clisp-gf-replacing-method-warning-motivation"></a>Motivation</h5></div></div></div><p>This warning can be warranted for the same reason as
 <a class="link" href="#mop-clisp-gf-already-called-warning-motivation" title="Motivation">above</a>:
 if the old method and the new method have a different contract,
 something is fishy and possibly wrong.
 Additionally, the programmers may not even have intended to replace the
 method. They may have intended cumulative effects of the two methods.
</p></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="class-obsolescence-warning"></a>29.12.1.3. Warning
  <code class="classname">CLOS:CLASS-OBSOLESCENCE-WARNING</code></h4></div></div></div><p>This is a hint that different parts of the program define the same
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_class.html" target="_top"><code class="classname">CLASS</code></a> incompatibly, and some objects, created to the old
specification, have been obsoleted by the new one.
Example: in addition to the code
 <a class="link" href="#mop-clisp-gf-already-called-warning-code">above</a>:
 </p><pre class="programlisting">
(defclass ware ()
  ((title :initarg :title :accessor title)
   (year :initarg :year :accessor year)))
</pre><p>
Evaluating the above will obsolete all objects of type
<code class="classname">ware</code>s, <code class="classname">book</code>s etc
created so far, i.e., their components will become inaccessible.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">This is a <code class="classname">STYLE-WARNING</code></h3><p>This warning is actually a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_style-warning.html" target="_top"><code class="classname">STYLE-WARNING</code></a> because it indicates the
  behavior officially sanctioned by the standard and useful in some situations.
  We only warn on it because it <span class="emphasis"><em>may</em></span> lead to confusing
  behavior for inexperienced users.</p></div><div class="simplesect"><div class="titlepage"><div><div><h5 class="title"><a id="class-obsolescence-warning-motivation"></a>Motivation</h5></div></div></div><p>In addition to the
 <a class="link" href="#mop-clisp-gf-already-called-warning-motivation" title="Motivation">above</a>,
 this warning tells the programmers that they are losing some objects
 they have already created.</p></div></div></div></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="gray"></a>Chapter 30. Gray streams</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#gray-overview">30.1. Overview</a></span></dt><dt><span class="section"><a href="#gray-classes">30.2. Defined classes</a></span></dt><dt><span class="section"><a href="#gray-gf-general">30.3. General generic functions</a></span></dt><dt><span class="section"><a href="#gray-gf-char-in">30.4. Generic functions for character input</a></span></dt><dt><span class="section"><a href="#gray-gf-char-out">30.5. Generic functions for character output</a></span></dt><dt><span class="section"><a href="#gray-gf-byte-in">30.6. Generic functions for binary input</a></span></dt><dt><span class="section"><a href="#gray-gf-byte-out">30.7. Generic functions for binary output</a></span></dt><dt><span class="section"><a href="#fill-stream">30.8. Class <code class="classname">EXT:FILL-STREAM</code></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="gray-overview"></a>30.1. Overview</h2></div></div></div><p>This interface permits the definition of new classes of streams,
and programming their behavior by defining methods for the elementary
stream operations.
It is based on the proposal <a class="ulink" href="http://www.nhplace.com/kent/CL/Issues/stream-definition-by-user.html" target="_top">STREAM-DEFINITION-BY-USER:GENERIC-FUNCTIONS</a> of David N. Gray to X3J13
and is supported by most <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> implementations currently in use.</p><p>All symbols defined by this interface, starting with the prefix
 <code class="literal">FUNDAMENTAL-</code> or <code class="literal">STREAM-</code>,
 are exported from the package <a class="link" href="#gray" title="Chapter 30. Gray streams"><strong class="package"><span class="quote">“<span class="quote">GRAY</span>”</span></strong></a>
 and <a class="link" href="#re-export" title="11.1.3. Function EXT:RE-EXPORT"><code class="function">EXT:RE-EXPORT</code></a>ed from <a class="link" href="#ext-pac"><strong class="package"><span class="quote">“<span class="quote">EXT</span>”</span></strong></a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="gray-classes"></a>30.2. Defined classes</h2></div></div></div><div class="variablelist"><p class="title"><strong>Defined classes</strong></p><dl class="variablelist"><dt><a id="fu-st"></a><span class="term"><a class="link" href="#fu-st"><code class="classname">GRAY:FUNDAMENTAL-STREAM</code></a></span></dt><dd>This is a superclass of all user-defined streams.
   It is a subclass of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> and of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_standard-object.html" target="_top"><code class="classname">STANDARD-OBJECT</code></a>.
   Its metaclass is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-class.html" target="_top"><code class="classname">STANDARD-CLASS</code></a>.</dd><dt><a id="fu-st-in"></a><span class="term"><a class="link" href="#fu-st-in"><code class="classname">GRAY:FUNDAMENTAL-INPUT-STREAM</code></a></span></dt><dd>This is a superclass of all user-defined <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_i.html#input">input</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s.
   It is a subclass of <a class="link" href="#fu-st"><code class="classname">GRAY:FUNDAMENTAL-STREAM</code></a>.  The built-in function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_input-str_put-stream-p.html" target="_top"><code class="function">INPUT-STREAM-P</code></a>
   returns true on instances of this class.  This means that when you
   define a new stream class capable of doing input, you have to make it
   a subclass of <a class="link" href="#fu-st-in"><code class="classname">GRAY:FUNDAMENTAL-INPUT-STREAM</code></a>.</dd><dt><a id="fu-st-out"></a><span class="term"><a class="link" href="#fu-st-out"><code class="classname">GRAY:FUNDAMENTAL-OUTPUT-STREAM</code></a></span></dt><dd>This is a superclass of all user-defined <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_o.html#output">output</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s.
   It is a subclass of <a class="link" href="#fu-st"><code class="classname">GRAY:FUNDAMENTAL-STREAM</code></a>.  The built-in function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_input-str_put-stream-p.html" target="_top"><code class="function">OUTPUT-STREAM-P</code></a>
   returns true on instances of this class.  This means that when you
   define a new stream class capable of doing output, you have to make
   it a subclass of <a class="link" href="#fu-st-out"><code class="classname">GRAY:FUNDAMENTAL-OUTPUT-STREAM</code></a>.</dd><dt><a id="fu-st-char"></a><span class="term"><a class="link" href="#fu-st-char"><code class="classname">GRAY:FUNDAMENTAL-CHARACTER-STREAM</code></a></span></dt><dd>This is a superclass of all user-defined streams
   whose <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>.  It is a subclass of
   <a class="link" href="#fu-st"><code class="classname">GRAY:FUNDAMENTAL-STREAM</code></a>.  It defines a method on <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> that returns
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>.</dd><dt><a id="fu-st-bin"></a><span class="term"><a class="link" href="#fu-st-bin"><code class="classname">GRAY:FUNDAMENTAL-BINARY-STREAM</code></a></span></dt><dd>This is a superclass of all user-defined streams
   whose <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> is a subtype of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>.  It is a
   subclass of <a class="link" href="#fu-st"><code class="classname">GRAY:FUNDAMENTAL-STREAM</code></a>.  When you define a subclass of <a class="link" href="#fu-st-bin"><code class="classname">GRAY:FUNDAMENTAL-BINARY-STREAM</code></a>,
   you have to provide a method on <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a>.
  </dd><dt><span class="term"><code class="classname">GRAY:FUNDAMENTAL-CHARACTER-INPUT-STREAM</code></span></dt><dd>This is a convenience class inheriting from both
   <a class="link" href="#fu-st-char"><code class="classname">GRAY:FUNDAMENTAL-CHARACTER-STREAM</code></a> and <a class="link" href="#fu-st-in"><code class="classname">GRAY:FUNDAMENTAL-INPUT-STREAM</code></a>.</dd><dt><span class="term"><code class="classname">GRAY:FUNDAMENTAL-CHARACTER-OUTPUT-STREAM</code></span></dt><dd>This is a convenience class inheriting from both
   <a class="link" href="#fu-st-char"><code class="classname">GRAY:FUNDAMENTAL-CHARACTER-STREAM</code></a> and <a class="link" href="#fu-st-out"><code class="classname">GRAY:FUNDAMENTAL-OUTPUT-STREAM</code></a>.</dd><dt><span class="term"><code class="classname">GRAY:FUNDAMENTAL-BINARY-INPUT-STREAM</code></span></dt><dd>This is a convenience class inheriting from both
   <a class="link" href="#fu-st-bin"><code class="classname">GRAY:FUNDAMENTAL-BINARY-STREAM</code></a> and <a class="link" href="#fu-st-in"><code class="classname">GRAY:FUNDAMENTAL-INPUT-STREAM</code></a>.</dd><dt><span class="term"><code class="classname">GRAY:FUNDAMENTAL-BINARY-OUTPUT-STREAM</code></span></dt><dd>This is a convenience class inheriting from both
   <a class="link" href="#fu-st-bin"><code class="classname">GRAY:FUNDAMENTAL-BINARY-STREAM</code></a> and <a class="link" href="#fu-st-out"><code class="classname">GRAY:FUNDAMENTAL-OUTPUT-STREAM</code></a>.</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="gray-gf-general"></a>30.3. General generic functions</h2></div></div></div><div class="variablelist"><p class="title"><strong>General generic functions defined on streams</strong></p><dl class="variablelist"><dt><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">Returns the stream's element type, normally a
   subtype of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>.</p><p class="simpara">The method for <a class="link" href="#fu-st-char"><code class="classname">GRAY:FUNDAMENTAL-CHARACTER-STREAM</code></a> returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>.
  </p></dd><dt><span class="term"><code class="code">((<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a>)
    <em class="replaceable"><code>new-element-type</code></em> <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">Changes the stream's element type.</p><p class="simpara">The default method <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>.</p><p class="simpara">This function is a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> extension (see <a class="xref" href="#stream-eltype" title="21.8. Function STREAM-ELEMENT-TYPE">Section 21.8, “Function <code class="function">STREAM-ELEMENT-TYPE</code>”</a>).</p></dd><dt><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a> <em class="replaceable"><code>stream</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    <code class="constant">:ABORT</code>)</code></span></dt><dd><p class="simpara">Closes the stream and flushes any associated buffers.
   </p><p class="simpara">When you define a primary method on this
    function, do not forget to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/locfun_call-next-method.html" target="_top"><code class="function">CALL-NEXT-METHOD</code></a>.
  </p></dd><dt><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_open-stream-p.html" target="_top"><code class="function">OPEN-STREAM-P</code></a> <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">Returns true before the stream has been closed, and
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> after the stream has been closed.</p><p class="simpara">You do not need to add methods to this function.</p></dd><dt><a id="st-position"></a><span class="term"><code class="code">(<a class="link" href="#st-position"><code class="function">GRAY:STREAM-POSITION</code></a>
    <em class="replaceable"><code>stream</code></em> <em class="replaceable"><code>position</code></em>)</code></span></dt><dd><p class="simpara">Just like <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_file-position.html" target="_top"><code class="function">FILE-POSITION</code></a>, but <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
    <em class="replaceable"><code>position</code></em> means inquire.</p><p class="simpara">You must define a method for this function.</p></dd><dt><a id="st-rd-seq"></a><span class="term"><code class="code">(GRAY:STREAM-READ-SEQUENCE
   <em class="replaceable"><code>sequence</code></em> <em class="replaceable"><code>stream</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:START</code> <code class="constant">:END</code>)</code></span></dt><dd><p class="simpara">Used by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-sequence.html" target="_top"><code class="function">READ-SEQUENCE</code></a>. <span class="emphasis"><em>Deprecated</em></span>.
    Define <a class="link" href="#st-rd-cs"><code class="function">GRAY:STREAM-READ-CHAR-SEQUENCE</code></a> or <a class="link" href="#st-rd-bs"><code class="function">GRAY:STREAM-READ-BYTE-SEQUENCE</code></a> and call <a class="link" href="#rd-ch-seq"><code class="function">EXT:READ-CHAR-SEQUENCE</code></a>/<a class="link" href="#rd-by-seq"><code class="function">EXT:READ-BYTE-SEQUENCE</code></a> instead.
   </p><p class="simpara">The default method calls <a class="link" href="#st-rd-cs"><code class="function">GRAY:STREAM-READ-CHAR-SEQUENCE</code></a> or <a class="link" href="#st-rd-bs"><code class="function">GRAY:STREAM-READ-BYTE-SEQUENCE</code></a>.
 </p></dd><dt><a id="st-wr-seq"></a><span class="term"><code class="code">(GRAY:STREAM-WRITE-SEQUENCE
   <em class="replaceable"><code>sequence</code></em> <em class="replaceable"><code>stream</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:START</code> <code class="constant">:END</code>)</code></span></dt><dd><p class="simpara">Used by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_write-sequence.html" target="_top"><code class="function">WRITE-SEQUENCE</code></a>. <span class="emphasis"><em>Deprecated</em></span>.
    Define <a class="link" href="#st-wr-cs"><code class="function">GRAY:STREAM-WRITE-CHAR-SEQUENCE</code></a> or <a class="link" href="#st-wr-bs"><code class="function">GRAY:STREAM-WRITE-BYTE-SEQUENCE</code></a> and call <a class="link" href="#wr-ch-seq"><code class="function">EXT:WRITE-CHAR-SEQUENCE</code></a>/<a class="link" href="#wr-by-seq"><code class="function">EXT:WRITE-BYTE-SEQUENCE</code></a> instead.
   </p><p class="simpara">The default method calls <a class="link" href="#st-wr-cs"><code class="function">GRAY:STREAM-WRITE-CHAR-SEQUENCE</code></a> or <a class="link" href="#st-wr-bs"><code class="function">GRAY:STREAM-WRITE-BYTE-SEQUENCE</code></a>.
 </p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="gray-gf-char-in"></a>30.4. Generic functions for character input</h2></div></div></div><div class="variablelist"><p class="title"><strong>Generic functions for character input</strong></p><dl class="variablelist"><dt><a id="st-rc"></a><span class="term"><code class="code">(<a class="link" href="#st-rc"><code class="function">GRAY:STREAM-READ-CHAR</code></a> <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">If a character was pushed back using <a class="link" href="#st-uc"><code class="function">GRAY:STREAM-UNREAD-CHAR</code></a>,
   returns and consumes it.  Otherwise returns and consumes the next
   character from the stream. Returns <code class="constant">:EOF</code> if the <code class="literal"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#end-of-stream">end-of-stream</a></code> is reached.
   </p><p class="simpara">You must define a method for this function.</p></dd><dt><a id="st-uc"></a><span class="term"><code class="code">(<a class="link" href="#st-uc"><code class="function">GRAY:STREAM-UNREAD-CHAR</code></a> <em class="replaceable"><code>stream</code></em> <em class="replaceable"><code>char</code></em>)</code></span></dt><dd><p class="simpara">Pushes <em class="replaceable"><code>char</code></em>, which must be the last character
   read from the <em class="replaceable"><code>stream</code></em>, back onto the front of the <em class="replaceable"><code>stream</code></em>.
   </p><p class="simpara">You must define a method for this function.</p></dd><dt><a id="st-rcnh"></a><span class="term"><code class="code">(<a class="link" href="#st-rcnh"><code class="function">GRAY:STREAM-READ-CHAR-NO-HANG</code></a> <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">Returns a character or <code class="constant">:EOF</code>, like <a class="link" href="#st-rc"><code class="function">GRAY:STREAM-READ-CHAR</code></a>, if
   that would return immediately.  If <a class="link" href="#st-rc"><code class="function">GRAY:STREAM-READ-CHAR</code></a>'s value is not available
   immediately, returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> instead of waiting.</p><p class="simpara">
   The default method simply calls <a class="link" href="#st-rc"><code class="function">GRAY:STREAM-READ-CHAR</code></a>; this is sufficient for streams
   whose <a class="link" href="#st-rc"><code class="function">GRAY:STREAM-READ-CHAR</code></a> method never blocks.</p></dd><dt><span class="term"><code class="code">(GRAY:STREAM-PEEK-CHAR <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">If a character was pushed back using <a class="link" href="#st-uc"><code class="function">GRAY:STREAM-UNREAD-CHAR</code></a>,
   returns it.  Otherwise returns the next character from the stream,
   avoiding any side effects <a class="link" href="#st-rc"><code class="function">GRAY:STREAM-READ-CHAR</code></a> would do.  Returns <code class="constant">:EOF</code> if the
   <code class="literal"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#end-of-stream">end-of-stream</a></code> is reached.</p><p class="simpara">The default method calls <a class="link" href="#st-rc"><code class="function">GRAY:STREAM-READ-CHAR</code></a> and <a class="link" href="#st-uc"><code class="function">GRAY:STREAM-UNREAD-CHAR</code></a>; this is
   sufficient for streams whose <a class="link" href="#st-rc"><code class="function">GRAY:STREAM-READ-CHAR</code></a> method has no
   side-effects.</p></dd><dt><span class="term"><code class="code">(GRAY:STREAM-LISTEN <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">If a character was pushed back using <a class="link" href="#st-uc"><code class="function">GRAY:STREAM-UNREAD-CHAR</code></a>,
   returns it.  Otherwise returns the next character from the stream, if
   already available.  If no character is available immediately, or if
   <code class="literal"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#end-of-stream">end-of-stream</a></code> is reached, returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</p><p class="simpara">The default method calls <a class="link" href="#st-rcnh"><code class="function">GRAY:STREAM-READ-CHAR-NO-HANG</code></a> and <a class="link" href="#st-uc"><code class="function">GRAY:STREAM-UNREAD-CHAR</code></a>; this is
   sufficient for streams whose <a class="link" href="#st-rc"><code class="function">GRAY:STREAM-READ-CHAR</code></a> method has no
   side-effects.</p></dd><dt><span class="term"><code class="code">(GRAY:STREAM-READ-CHAR-WILL-HANG-P
    <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">Returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if <a class="link" href="#st-rc"><code class="function">GRAY:STREAM-READ-CHAR</code></a> will return immediately.
   Otherwise it returns true.</p><p class="simpara">The default method calls <a class="link" href="#st-rcnh"><code class="function">GRAY:STREAM-READ-CHAR-NO-HANG</code></a> and <a class="link" href="#st-uc"><code class="function">GRAY:STREAM-UNREAD-CHAR</code></a>; this is
   sufficient for streams whose <a class="link" href="#st-rc"><code class="function">GRAY:STREAM-READ-CHAR</code></a> method has no side-effects.</p><p class="simpara">This function is a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> extension (see <a class="link" href="#rcwhp"><code class="function">EXT:READ-CHAR-WILL-HANG-P</code></a>).</p></dd><dt><a id="st-rd-cs"></a><span class="term"><code class="code">(<a class="link" href="#st-rd-cs"><code class="function">GRAY:STREAM-READ-CHAR-SEQUENCE</code></a>
   <em class="replaceable"><code>stream</code></em> <em class="replaceable"><code>sequence</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> [<em class="replaceable"><code>start</code></em> [<em class="replaceable"><code>end</code></em>]])</code></span></dt><dd><p class="simpara">Fills the subsequence of <em class="replaceable"><code>sequence</code></em> specified by
   <code class="constant">:START</code> and <code class="constant">:END</code> with characters consecutively read from <em class="replaceable"><code>stream</code></em>.
   Returns the index of the first element of <em class="replaceable"><code>sequence</code></em> that was not
   updated (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eqcm_sleq__lteqcm_gteq.html" target="_top"><code class="function">=</code></a> <em class="replaceable"><code>end</code></em>, or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eqcm_sleq__lteqcm_gteq.html" target="_top"><code class="function">&lt;</code></a> <em class="replaceable"><code>end</code></em> if the stream reached its end).
   </p><p class="simpara"><em class="replaceable"><code>sequence</code></em> is an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_array.html" target="_top"><code class="classname">ARRAY</code></a> of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>s, i.e. a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>.
   <em class="replaceable"><code>start</code></em> is a nonnegative <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> and defaults to <code class="literal">0</code>.
   <em class="replaceable"><code>end</code></em> is a nonnegative <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and defaults to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>,
   which stands for <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_length.html" target="_top"><code class="function">LENGTH</code></a> <em class="replaceable"><code>sequence</code></em>)</code>.
  </p><p class="simpara">The default method repeatedly calls <a class="link" href="#st-rc"><code class="function">GRAY:STREAM-READ-CHAR</code></a>; this
   is always sufficient if speed does not matter.</p><p class="simpara">This function is a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> extension (see
   <a class="link" href="#rd-ch-seq"><code class="function">EXT:READ-CHAR-SEQUENCE</code></a>).</p></dd><dt><span class="term"><code class="code">(GRAY:STREAM-READ-LINE <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">Reads a line of characters, and return two values:
   the line (a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>, without the terminating <span class="keysym">#\Newline</span> character),
   and a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_boolean.html" target="_top"><code class="classname">BOOLEAN</code></a> value which is true if the line was terminated by
   <code class="literal"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#end-of-stream">end-of-stream</a></code> instead of <span class="keysym">#\Newline</span>.</p><p class="simpara">The default method repeatedly calls <a class="link" href="#st-rc"><code class="function">GRAY:STREAM-READ-CHAR</code></a>; this
   is always sufficient.</p></dd><dt><span class="term"><code class="code">(GRAY:STREAM-CLEAR-INPUT <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">Clears all pending interactive input from the
   <em class="replaceable"><code>stream</code></em>, and returns true if some pending input was removed.</p><p class="simpara">The default method does nothing and returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>; this is
   sufficient for non-interactive streams.</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="gray-gf-char-out"></a>30.5. Generic functions for character output</h2></div></div></div><div class="variablelist"><p class="title"><strong>Generic functions for character output</strong></p><dl class="variablelist"><dt><a id="st-wc"></a><span class="term"><code class="code">(<a class="link" href="#st-wc"><code class="function">GRAY:STREAM-WRITE-CHAR</code></a> <em class="replaceable"><code>stream</code></em> <em class="replaceable"><code>char</code></em>)</code></span></dt><dd><p class="simpara">Writes <em class="replaceable"><code>char</code></em>.
   </p><p class="simpara">You must define a method for this function.</p></dd><dt><a id="st-lc"></a><span class="term"><code class="code">(<a class="link" href="#st-lc"><code class="function">GRAY:STREAM-LINE-COLUMN</code></a> <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">Returns the column number where the next character
   would be written (<code class="literal">0</code> stands for the first column),
    or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if that is not meaningful for this stream.
   </p><p class="simpara">You must define a method for this function.</p></dd><dt><span class="term"><code class="code">(GRAY:STREAM-START-LINE-P <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">Returns true if the next character would be
   written at the start of a new line.</p><p class="simpara">The default method calls <a class="link" href="#st-lc"><code class="function">GRAY:STREAM-LINE-COLUMN</code></a> and compares its result with
   0; this is sufficient for streams whose <a class="link" href="#st-lc"><code class="function">GRAY:STREAM-LINE-COLUMN</code></a> never returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
  </p></dd><dt><a id="st-wr-cs"></a><span class="term"><code class="code">(<a class="link" href="#st-wr-cs"><code class="function">GRAY:STREAM-WRITE-CHAR-SEQUENCE</code></a>
    <em class="replaceable"><code>stream</code></em> <em class="replaceable"><code>sequence</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> [<em class="replaceable"><code>start</code></em> [<em class="replaceable"><code>end</code></em>]])</code></span></dt><dd><p class="simpara">Outputs the subsequence of <em class="replaceable"><code>sequence</code></em> specified
   by <code class="constant">:START</code> and <code class="constant">:END</code> to <em class="replaceable"><code>stream</code></em>.</p><p class="simpara"><em class="replaceable"><code>sequence</code></em> is an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_array.html" target="_top"><code class="classname">ARRAY</code></a> of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>s, i.e. a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>.
   <em class="replaceable"><code>start</code></em> is a nonnegative <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> and defaults to 0.
   <em class="replaceable"><code>end</code></em> is a nonnegative integer or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and defaults to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>,
   which stands for <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_length.html" target="_top"><code class="function">LENGTH</code></a> <em class="replaceable"><code>sequence</code></em>)</code>.
  </p><p class="simpara">The default method repeatedly calls <a class="link" href="#st-wc"><code class="function">GRAY:STREAM-WRITE-CHAR</code></a>; this
   is always sufficient if speed does not matter.
  </p><p class="simpara">This function is a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> extension
   (see <a class="link" href="#wr-ch-seq"><code class="function">EXT:WRITE-CHAR-SEQUENCE</code></a>).</p></dd><dt><span class="term"><code class="code">(GRAY:STREAM-WRITE-STRING
    <em class="replaceable"><code>stream</code></em> <em class="replaceable"><code>string</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> [<em class="replaceable"><code>start</code></em> [<em class="replaceable"><code>end</code></em>]])</code></span></dt><dd><p class="simpara">Outputs the subsequence of <em class="replaceable"><code>string</code></em> specified by
   <code class="constant">:START</code> and <code class="constant">:END</code> to <em class="replaceable"><code>stream</code></em>.  Returns <em class="replaceable"><code>string</code></em>.</p><p class="simpara"><em class="replaceable"><code>string</code></em> is a string.  <em class="replaceable"><code>start</code></em> is a nonnegative integer
   and default to 0.  <em class="replaceable"><code>end</code></em> is a nonnegative integer or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and
   defaults to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, which stands for <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_length.html" target="_top"><code class="function">LENGTH</code></a> <em class="replaceable"><code>string</code></em>)</code>.
   </p><p class="simpara">The default method calls <a class="link" href="#st-wr-cs"><code class="function">GRAY:STREAM-WRITE-CHAR-SEQUENCE</code></a>;
   this is always sufficient.</p></dd><dt><span class="term"><code class="code">(GRAY:STREAM-TERPRI <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">Outputs a <span class="keysym">#\Newline</span> character.</p><p class="simpara">The default method calls <a class="link" href="#st-wc"><code class="function">GRAY:STREAM-WRITE-CHAR</code></a>; this is always
   sufficient.</p></dd><dt><span class="term"><code class="code">(GRAY:STREAM-FRESH-LINE <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">Possibly outputs a <span class="keysym">#\Newline</span> character, so as to ensure
   that the next character would be written at the start of a new line.
   Returns true if it did output a <span class="keysym">#\Newline</span> character.</p><p class="simpara">The default method calls
   <code class="function">GRAY:STREAM-START-LINE-P</code> and then
   <code class="function">GRAY:STREAM-TERPRI</code> if necessary; this is always
   sufficient.</p></dd><dt><span class="term"><code class="code">(GRAY:STREAM-FINISH-OUTPUT <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">Ensures that any buffered output has reached its
   destination, and then returns.</p><p class="simpara">The default method does nothing.</p></dd><dt><span class="term"><code class="code">(GRAY:STREAM-FORCE-OUTPUT <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">Brings any buffered output on its way towards its
   destination, and returns without waiting until it has reached its
   destination.</p><p class="simpara">The default method does nothing.</p></dd><dt><span class="term"><code class="code">(GRAY:STREAM-CLEAR-OUTPUT <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">Attempts to discard any buffered output which has
   not yet reached its destination.</p><p class="simpara">The default method does nothing.</p></dd><dt><span class="term"><code class="code">(GRAY:STREAM-ADVANCE-TO-COLUMN
    <em class="replaceable"><code>stream</code></em> <em class="replaceable"><code>column</code></em>)</code></span></dt><dd><p class="simpara">Ensures that the next character will be written at
    least at <em class="replaceable"><code>column</code></em>.</p><p class="simpara">The default method outputs an appropriate amount of space
   characters; this is sufficient for non-proportional output.</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="gray-gf-byte-in"></a>30.6. Generic functions for binary input</h2></div></div></div><div class="variablelist"><p class="title"><strong>Generic functions for binary input</strong></p><dl class="variablelist"><dt><a id="st-rb"></a><span class="term"><code class="code">(<a class="link" href="#st-rb"><code class="function">GRAY:STREAM-READ-BYTE</code></a> <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">Returns and consumes the next integer from the
   stream. Returns <code class="constant">:EOF</code> if the <code class="literal"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#end-of-stream">end-of-stream</a></code> is reached.</p><p class="simpara">You must define a method for this function.</p></dd><dt><a id="st-rbla"></a><span class="term"><code class="code">(<a class="link" href="#st-rbla"><code class="function">GRAY:STREAM-READ-BYTE-LOOKAHEAD</code></a> <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">To be called only if <em class="replaceable"><code>stream</code></em>'s
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> is <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span> or <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_signed-byte.html" target="_top"><code class="classname">SIGNED-BYTE</code></a> 8)</code></span>.
   Returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> if <a class="link" href="#st-rb"><code class="function">GRAY:STREAM-READ-BYTE</code></a> would return immediately with an
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> result.  Returns <code class="constant">:EOF</code> if the <code class="literal"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_e.html#end-of-stream">end-of-stream</a></code> is already
   known to be reached.  If <a class="link" href="#st-rb"><code class="function">GRAY:STREAM-READ-BYTE</code></a>'s value is not available
   immediately, returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> instead of waiting.</p><p class="simpara">You must define a method for this function.</p><p class="simpara">This function is a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> extension (see
   <a class="link" href="#rbla"><code class="function">EXT:READ-BYTE-LOOKAHEAD</code></a>).</p></dd><dt><a id="st-rbwhp"></a><span class="term"><code class="code">(<a class="link" href="#rbwhp"><code class="function">GRAY:STREAM-READ-BYTE-WILL-HANG-P</code></a> <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">To be called only if <em class="replaceable"><code>stream</code></em>'s
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> is <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span> or <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_signed-byte.html" target="_top"><code class="classname">SIGNED-BYTE</code></a> 8)</code></span>.
   Returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if <a class="link" href="#st-rb"><code class="function">GRAY:STREAM-READ-BYTE</code></a> will return immediately.
   Otherwise it returns true.</p><p class="simpara">The default method calls <a class="link" href="#st-rbla"><code class="function">GRAY:STREAM-READ-BYTE-LOOKAHEAD</code></a>; this is always sufficient.
   </p><p class="simpara">This function is a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> extension (see <a class="link" href="#rbwhp"><code class="function">EXT:READ-BYTE-WILL-HANG-P</code></a>).
 </p></dd><dt><a id="st-rbnh"></a><span class="term"><code class="code">(<a class="link" href="#rbnh"><code class="function">GRAY:STREAM-READ-BYTE-NO-HANG</code></a> <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd><p class="simpara">To be called only if <em class="replaceable"><code>stream</code></em>'s
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> is <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span> or <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_signed-byte.html" target="_top"><code class="classname">SIGNED-BYTE</code></a> 8)</code></span>.
   Returns an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> or <code class="constant">:EOF</code>, like <a class="link" href="#st-rb"><code class="function">GRAY:STREAM-READ-BYTE</code></a>, if that would
   return immediately.  If <a class="link" href="#st-rb"><code class="function">GRAY:STREAM-READ-BYTE</code></a>'s value is not available immediately,
   returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> instead of waiting.</p><p class="simpara">The default method calls <a class="link" href="#st-rb"><code class="function">GRAY:STREAM-READ-BYTE</code></a> if <a class="link" href="#st-rbla"><code class="function">GRAY:STREAM-READ-BYTE-LOOKAHEAD</code></a> returns true;
    this is always sufficient.</p><p class="simpara">This function is a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> extension (see <a class="link" href="#rbnh"><code class="function">EXT:READ-BYTE-NO-HANG</code></a>).
 </p></dd><dt><a id="st-rd-bs"></a><span class="term"><code class="code">(<a class="link" href="#st-rd-bs"><code class="function">GRAY:STREAM-READ-BYTE-SEQUENCE</code></a>
    <em class="replaceable"><code>stream</code></em> <em class="replaceable"><code>sequence</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
    [<em class="replaceable"><code>start</code></em> [<em class="replaceable"><code>end</code></em> [<em class="replaceable"><code>no-hang</code></em> [<em class="replaceable"><code>interactive</code></em>]]]])</code></span></dt><dd><p class="simpara">Fills the subsequence of <em class="replaceable"><code>sequence</code></em> specified by
    <code class="constant">:START</code> and <code class="constant">:END</code> with integers consecutively read from <em class="replaceable"><code>stream</code></em>.
    Returns the index of the first element of <em class="replaceable"><code>sequence</code></em> that was not
    updated (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eqcm_sleq__lteqcm_gteq.html" target="_top"><code class="function">=</code></a> <em class="replaceable"><code>end</code></em>, or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eqcm_sleq__lteqcm_gteq.html" target="_top"><code class="function">&lt;</code></a> <em class="replaceable"><code>end</code></em> if the stream reached its end).
   </p><p class="simpara"><em class="replaceable"><code>sequence</code></em> is an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_array.html" target="_top"><code class="classname">ARRAY</code></a> of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>s.
    <em class="replaceable"><code>start</code></em> is a nonnegative <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> and defaults to 0.
    <em class="replaceable"><code>end</code></em> is a nonnegative <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and defaults to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>,
    which stands for <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_length.html" target="_top"><code class="function">LENGTH</code></a> <em class="replaceable"><code>sequence</code></em>)</code>.
    If <em class="replaceable"><code>no-hang</code></em> is true, the function should avoid blocking and instead fill
    only as many elements as are immediately available. If <em class="replaceable"><code>no-hang</code></em> is false
    and <em class="replaceable"><code>interactive</code></em> is true, the function can block for reading the first
    byte but should avoid blocking for any further bytes.</p><p class="simpara">The default method repeatedly calls <a class="link" href="#st-rb"><code class="function">GRAY:STREAM-READ-BYTE</code></a>; this
    is always sufficient if speed does not matter.</p><p class="simpara">This function is a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> extension (see
    <a class="link" href="#rd-by-seq"><code class="function">EXT:READ-BYTE-SEQUENCE</code></a>).</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="gray-gf-byte-out"></a>30.7. Generic functions for binary output</h2></div></div></div><div class="variablelist"><p class="title"><strong>Generic functions for binary output</strong></p><dl class="variablelist"><dt><span class="term"><code class="code">(GRAY:STREAM-WRITE-BYTE
    <em class="replaceable"><code>stream</code></em> <em class="replaceable"><code>integer</code></em>)</code></span></dt><dd><p class="simpara">Writes <em class="replaceable"><code>integer</code></em>.</p><p class="simpara">You must define a method for this function.</p></dd><dt><a id="st-wr-bs"></a><span class="term"><code class="code">(<a class="link" href="#st-wr-bs"><code class="function">GRAY:STREAM-WRITE-BYTE-SEQUENCE</code></a>
    <em class="replaceable"><code>stream</code></em> <em class="replaceable"><code>sequence</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
    [<em class="replaceable"><code>start</code></em> [<em class="replaceable"><code>end</code></em> [<em class="replaceable"><code>no-hang</code></em> [<em class="replaceable"><code>interactive</code></em>]]]])</code></span></dt><dd><p class="simpara">Outputs the subsequence of <em class="replaceable"><code>sequence</code></em> specified
    by <code class="constant">:START</code> and <code class="constant">:END</code> to <em class="replaceable"><code>stream</code></em></p><p class="simpara"><em class="replaceable"><code>sequence</code></em> is an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_array.html" target="_top"><code class="classname">ARRAY</code></a> of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>s.
    <em class="replaceable"><code>start</code></em> is a nonnegative <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> and defaults to 0.
    <em class="replaceable"><code>end</code></em> is a nonnegative <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and defaults to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>,
    which stands for <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_length.html" target="_top"><code class="function">LENGTH</code></a> <em class="replaceable"><code>sequence</code></em>)</code>.
    If <em class="replaceable"><code>no-hang</code></em> is true, the function should avoid blocking and instead output
    only as many elements as it can immediately proceed. If <em class="replaceable"><code>no-hang</code></em> is false
    and <em class="replaceable"><code>interactive</code></em> is true, the function can block for writing the first
    byte but should avoid blocking for any further bytes.</p><p class="simpara">The default method repeatedly calls
    <code class="function">GRAY:STREAM-WRITE-BYTE</code>; this is always
    sufficient if speed does not matter.</p><p class="simpara">This function is a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> extension (see
    <a class="link" href="#wr-by-seq"><code class="function">EXT:WRITE-BYTE-SEQUENCE</code></a>).</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="fill-stream"></a>30.8. Class <a class="link" href="#fill-stream" title="30.8. Class EXT:FILL-STREAM"><code class="classname">EXT:FILL-STREAM</code></a></h2></div></div></div><div class="list-of-examples"><p><strong>List of Examples</strong></p><dl><dt>30.1. <a href="#ex-fill-stream">Example of <code class="classname">EXT:FILL-STREAM</code> usage</a></dt></dl></div><p>As an example of the use of <a class="link" href="#gray" title="Chapter 30. Gray streams"><strong class="package"><span class="quote">“<span class="quote">GRAY</span>”</span></strong></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s, <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
 offers an additional class, <a class="link" href="#fill-stream" title="30.8. Class EXT:FILL-STREAM"><code class="classname">EXT:FILL-STREAM</code></a>.  An instance of this class
 is a <span class="quote">“<span class="quote">formatting</span>”</span> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>, which makes the final
 output to the underlying stream look neat: indented and filled.
 An instance of <a class="link" href="#fill-stream" title="30.8. Class EXT:FILL-STREAM"><code class="classname">EXT:FILL-STREAM</code></a> is created like this:
</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a> '<a class="link" href="#fill-stream" title="30.8. Class EXT:FILL-STREAM"><code class="classname">EXT:FILL-STREAM</code></a> :stream <em class="replaceable"><code>stream</code></em>
               [:text-indent symbol-or-number]
               [:sexp-indent symbol-or-number-or-function])
</pre><p>where</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>stream</code></em></span></dt><dd>is the target <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> where the output actually
    goes.</dd><dt><span class="term"><em class="replaceable"><code>symbol-or-number</code></em></span></dt><dd>is the variable whose value is the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> text
    indentation or the indentation itself (defaults to 0).
 </dd><dt><span class="term"><em class="replaceable"><code>symbol-or-number-or-function</code></em></span></dt><dd><p>When <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> writes an S-expression to a
    <a class="link" href="#fill-stream" title="30.8. Class EXT:FILL-STREAM"><code class="classname">EXT:FILL-STREAM</code></a> using <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_22-3-4-2.html"><code class="literal">~S</code></a>, and the expression's printed
    representation does not fit on the current line, it is printed on
    separate lines, ignoring the prescribed text indentation and
    preserving spacing.  When this argument is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the
    S-expression <span class="strong"><strong>is</strong></span> indented by:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a></span></dt><dd>the text indentation above;
     </dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_symbol-value.html" target="_top"><code class="function">SYMBOL-VALUE</code></a> is the indentation;
     </dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a></span></dt><dd>the indentation itself;
     </dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a></span></dt><dd>called with one argument, the text indentation,
        and the value is used as S-expression indentation;
        thus <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_identity.html" target="_top"><code class="function">IDENTITY</code></a> is equivalent to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> above.
    </dd></dl></div><p>
    Defaults to <a href="impnotes.html#fill-stream" class="olink"><code class="varname">CUSTOM:*FILL-INDENT-SEXP*</code></a>, whose initial value is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_1plcm_1-.html" target="_top"><code class="function">1+</code></a>.
</p></dd></dl></div><p></p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>Note that, due to buffering, one must call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_finish-ou_clear-output.html" target="_top"><code class="function">FORCE-OUTPUT</code></a>
 when done with the <a class="link" href="#fill-stream" title="30.8. Class EXT:FILL-STREAM"><code class="classname">EXT:FILL-STREAM</code></a> (and before changing the indent variable).
 The former is done automatically by the macro
<code class="code">(with-fill-stream (fill target-stream ...) ...)</code>.</p></div><div class="example"><a id="ex-fill-stream"></a><p class="title"><strong>Example 30.1. Example of <a class="link" href="#fill-stream" title="30.8. Class EXT:FILL-STREAM"><code class="classname">EXT:FILL-STREAM</code></a> usage</strong></p><div class="example-contents"><pre class="programlisting">
(defvar *my-indent-level*)
(with-output-to-string (out)
  (let ((*print-right-margin* 20)
        (*print-pretty* t)
        (*my-indent-level* 2))
    (with-fill-stream (fill out :text-indent '*my-indent-level*)
      (format fill "~%this is some long sentence which will      be broken at spaces")
      (force-output fill)
      (let ((*my-indent-level* 5))
        (format fill "~%and    properly indented to the level specified by the ~S argument which can be a ~S or an ~S - cool!"
                :TEXT-INDENT 'symbol 'integer)
        (force-output fill))
      (format fill "~%Don't forget  to call ~S on it, and/or use ~S   Pretty formatting of the  S-expressions    printed with ~~S is  preserved: ~S"
              'force-output 'with-fill-stream '(defun foo (x y z) (if x (+ y z) (* y z)))))))
⇒ <code class="computeroutput">"
  this is some long
  sentence which
  will be broken at
  spaces
     and properly
     indented to
     the level
     specified by
     the
     :TEXT-INDENT
     argument which
     can be a
     SYMBOL or an
     INTEGER -
     cool!
  Don't forget to
  call FORCE-OUTPUT
  on it, and/or use
  WITH-FILL-STREAM
  Pretty formatting
  of the
  S-expressions
  printed with ~S
  is preserved:
   (DEFUN FOO
    (X Y Z)
    (IF X (+ Y Z)
     (* Y Z)))
"</code></pre></div></div><br class="example-break" /></div></div></div><div class="part"><div class="titlepage"><div><div><h1 class="title"><a id="ext-clisp"></a>Part III. Extensions Specific to <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a></h1></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="chapter"><a href="#ext-p-indep">31. Platform Independent Extensions</a></span></dt><dd><dl><dt><span class="section"><a href="#custom-init-fini">31.1. Customizing <span class="command"><strong>CLISP</strong></span> Process   Initialization and Termination</a></span></dt><dd><dl><dt><span class="section"><a href="#cradle-grave">31.1.1. Cradle to Grave</a></span></dt><dt><span class="section"><a href="#init-hooks">31.1.2. Customizing Initialization</a></span></dt><dt><span class="section"><a href="#fini-hooks">31.1.3. Customizing Termination</a></span></dt></dl></dd><dt><span class="section"><a href="#image">31.2. Saving an Image</a></span></dt><dd><dl><dt><span class="section"><a href="#image-portability">31.2.1. Image Portability</a></span></dt></dl></dd><dt><span class="section"><a href="#quit">31.3. Quitting <span class="command"><strong>CLISP</strong></span></a></span></dt><dt><span class="section"><a href="#i18n">31.4. Internationalization of <span class="command"><strong>CLISP</strong></span></a></span></dt><dd><dl><dt><span class="section"><a href="#language">31.4.1. The Language</a></span></dt></dl></dd><dt><span class="section"><a href="#encoding">31.5. Encodings</a></span></dt><dd><dl><dt><span class="section"><a href="#encodings-intro">31.5.1. Introduction</a></span></dt><dt><span class="section"><a href="#charset">31.5.2. Character Sets</a></span></dt><dt><span class="section"><a href="#newline">31.5.3. Line Terminators</a></span></dt><dt><span class="section"><a href="#make-encoding">31.5.4. Function <code class="function">EXT:MAKE-ENCODING</code></a></span></dt><dt><span class="section"><a href="#enc-charset">31.5.5. Function <code class="function">EXT:ENCODING-CHARSET</code></a></span></dt><dt><span class="section"><a href="#enc-dflt">31.5.6. Default encodings</a></span></dt><dt><span class="section"><a href="#string-byte">31.5.7. Converting between strings and byte vectors</a></span></dt></dl></dd><dt><span class="section"><a href="#gstream">31.6. Generic streams</a></span></dt><dt><span class="section"><a href="#weak">31.7. Weak Objects</a></span></dt><dd><dl><dt><span class="section"><a href="#weak-pointer">31.7.1. Weak Pointers</a></span></dt><dt><span class="section"><a href="#weak-list">31.7.2. Weak Lists</a></span></dt><dt><span class="section"><a href="#weak-and-relation">31.7.3. Weak <span class="quote">“<span class="quote">And</span>”</span> Relations</a></span></dt><dt><span class="section"><a href="#weak-or-relation">31.7.4. Weak <span class="quote">“<span class="quote">Or</span>”</span> Relations</a></span></dt><dt><span class="section"><a href="#weak-mapping">31.7.5. Weak Associations</a></span></dt><dt><span class="section"><a href="#weak-and-mapping">31.7.6. Weak <span class="quote">“<span class="quote">And</span>”</span> Mappings</a></span></dt><dt><span class="section"><a href="#weak-or-mapping">31.7.7. Weak <span class="quote">“<span class="quote">Or</span>”</span> Mappings</a></span></dt><dt><span class="section"><a href="#weak-alist">31.7.8. Weak Association Lists</a></span></dt><dt><span class="section"><a href="#weak-ht">31.7.9. Weak Hash Tables</a></span></dt></dl></dd><dt><span class="section"><a href="#final">31.8. Finalization</a></span></dt><dt><span class="section"><a href="#prompt">31.9. The Prompt</a></span></dt><dt><span class="section"><a href="#ansi">31.10. Maximum ANSI CL compliance</a></span></dt><dt><span class="section"><a href="#macros3">31.11. Additional Fancy Macros and Functions</a></span></dt><dd><dl><dt><span class="section"><a href="#ethe">31.11.1. Macro <code class="function">EXT:ETHE</code></a></span></dt><dt><span class="section"><a href="#letf">31.11.2. Macros <code class="function">EXT:LETF</code> &amp; <code class="function">EXT:LETF*</code></a></span></dt><dt><span class="section"><a href="#memoized">31.11.3. Macro <code class="function">EXT:MEMOIZED</code></a></span></dt><dt><span class="section"><a href="#with-collect">31.11.4. Macro <code class="function">EXT:WITH-COLLECT</code></a></span></dt><dt><span class="section"><a href="#compile-time-value">31.11.5. Macro <code class="function">EXT:COMPILE-TIME-VALUE</code></a></span></dt><dt><span class="section"><a href="#with-gensyms">31.11.6. Macro <code class="function">EXT:WITH-GENSYMS</code></a></span></dt><dt><span class="section"><a href="#remove-plist">31.11.7. Function <code class="function">EXT:REMOVE-PLIST</code></a></span></dt><dt><span class="section"><a href="#html-http-output">31.11.8. Macros <code class="function">EXT:WITH-HTML-OUTPUT</code> and   <code class="function">EXT:WITH-HTTP-OUTPUT</code></a></span></dt><dt><span class="section"><a href="#open-http">31.11.9. Function <code class="function">EXT:OPEN-HTTP</code> and   macro <code class="function">EXT:WITH-HTTP-INPUT</code></a></span></dt><dt><span class="section"><a href="#http-log-stream">31.11.10. Variable <code class="varname">CUSTOM:*HTTP-LOG-STREAM*</code></a></span></dt><dt><span class="section"><a href="#browse-url">31.11.11. Function <code class="function">EXT:BROWSE-URL</code></a></span></dt><dt><span class="section"><a href="#http-proxy">31.11.12. Variable <code class="varname">CUSTOM:*HTTP-PROXY*</code></a></span></dt><dt><span class="section"><a href="#canonicalize">31.11.13. Function <code class="function">EXT:CANONICALIZE</code></a></span></dt></dl></dd><dt><span class="section"><a href="#customize">31.12. Customizing <span class="command"><strong>CLISP</strong></span> behavior</a></span></dt><dt><span class="section"><a href="#code-walk">31.13. Code Walker</a></span></dt></dl></dd><dt><span class="chapter"><a href="#ext-platform">32. Platform Specific Extensions</a></span></dt><dd><dl><dt><span class="section"><a href="#screen">32.1. Random Screen Access</a></span></dt><dt><span class="section"><a href="#modules">32.2. External Modules</a></span></dt><dd><dl><dt><span class="section"><a href="#mod-overview">32.2.1. Overview</a></span></dt><dt><span class="section"><a href="#modinit">32.2.2. Module initialization</a></span></dt><dt><span class="section"><a href="#modfini">32.2.3. Module finalization</a></span></dt><dt><span class="section"><a href="#modinfo">32.2.4. Function <code class="function">EXT:MODULE-INFO</code></a></span></dt><dt><span class="section"><a href="#mod-dynload">32.2.5. Dynamic module loading</a></span></dt><dt><span class="section"><a href="#mod-set-example">32.2.6. Example</a></span></dt><dt><span class="section"><a href="#module-tools">32.2.7. Module tools</a></span></dt><dt><span class="section"><a href="#mod-ffi-vs-c">32.2.8. Trade-offs: <strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong> vs. <span class="command"><strong>C</strong></span>   modules</a></span></dt><dt><span class="section"><a href="#included-modules">32.2.9. Modules included in the source distribution</a></span></dt></dl></dd><dt><span class="section"><a href="#dffi">32.3. The Foreign Function Call Facility</a></span></dt><dd><dl><dt><span class="section"><a href="#dffi-intro">32.3.1. Introduction</a></span></dt><dt><span class="section"><a href="#dffi-overview">32.3.2. Overview</a></span></dt><dt><span class="section"><a href="#dffi-types">32.3.3. (Foreign) <span class="command"><strong>C</strong></span> types</a></span></dt><dt><span class="section"><a href="#c-flavor">32.3.4. The choice of the <span class="command"><strong>C</strong></span> flavor</a></span></dt><dt><span class="section"><a href="#dffi-variables">32.3.5. Foreign variables</a></span></dt><dt><span class="section"><a href="#dffi-places">32.3.6. Operations on foreign places</a></span></dt><dt><span class="section"><a href="#dffi-functions">32.3.7. Foreign functions</a></span></dt><dt><span class="section"><a href="#allocation">32.3.8. Argument and result passing conventions</a></span></dt><dt><span class="section"><a href="#param-mode">32.3.9. Parameter Mode</a></span></dt><dt><span class="section"><a href="#dffi-examples">32.3.10. Examples</a></span></dt></dl></dd><dt><span class="section"><a href="#socket">32.4. Socket Streams</a></span></dt><dd><dl><dt><span class="section"><a href="#socket-intro">32.4.1. Introduction</a></span></dt><dt><span class="section"><a href="#socket-api">32.4.2. Socket API Reference</a></span></dt><dt><span class="section"><a href="#timeout-k">32.4.3. Argument <code class="constant">:TIMEOUT</code></a></span></dt></dl></dd><dt><span class="section"><a href="#mt">32.5. Multiple Threads of Execution</a></span></dt><dd><dl><dt><span class="section"><a href="#mt-intro">32.5.1. Introduction</a></span></dt><dt><span class="section"><a href="#mt-general">32.5.2. General principles</a></span></dt><dt><span class="section"><a href="#mt-api">32.5.3. Thread API reference</a></span></dt></dl></dd><dt><span class="section"><a href="#quickstart">32.6. Quickstarting delivery with <span class="command"><strong>CLISP</strong></span></a></span></dt><dd><dl><dt><span class="section"><a href="#quickstart-summary">32.6.1. Summary</a></span></dt><dt><span class="section"><a href="#quickstart-unix">32.6.2. Scripting with <span class="command"><strong>CLISP</strong></span></a></span></dt><dt><span class="section"><a href="#quickstart-desktop">32.6.3. Desktop Environments</a></span></dt><dt><span class="section"><a href="#quickstart-linux">32.6.4. Associating extensions with <span class="command"><strong>CLISP</strong></span> via kernel</a></span></dt></dl></dd><dt><span class="section"><a href="#shell">32.7. Shell, Pipes and Printing</a></span></dt><dd><dl><dt><span class="section"><a href="#exec">32.7.1. Shell</a></span></dt><dt><span class="section"><a href="#pipe">32.7.2. Pipes</a></span></dt><dt><span class="section"><a href="#hardcopy">32.7.3. Printing</a></span></dt></dl></dd><dt><span class="section"><a href="#getenv">32.8. Operating System Environment</a></span></dt></dl></dd><dt><span class="chapter"><a href="#ext-modules">33. Extensions Implemented as Modules</a></span></dt><dd><dl><dt><span class="section"><a href="#asdf">33.1. A System Definition Facility</a></span></dt><dt><span class="section"><a href="#syscalls">33.2. System Calls</a></span></dt><dd><dl><dt><span class="section"><a href="#neworking">33.2.1. Networking</a></span></dt><dt><span class="section"><a href="#file-system">33.2.2. File system</a></span></dt><dt><span class="section"><a href="#user-group">33.2.3. Users and Groups</a></span></dt><dt><span class="section"><a href="#sysinfo">33.2.4. System Information</a></span></dt><dt><span class="section"><a href="#posix-math">33.2.5. Mathematical functions</a></span></dt><dt><span class="section"><a href="#encryption">33.2.6. Encryption</a></span></dt><dt><span class="section"><a href="#sys-log">33.2.7. Syslog</a></span></dt><dt><span class="section"><a href="#processes">33.2.8. Processes</a></span></dt><dt><span class="section"><a href="#accounting">33.2.9. Accounting</a></span></dt><dt><span class="section"><a href="#posix-time">33.2.10. Time and Data Conversion</a></span></dt><dt><span class="section"><a href="#strverscmp">33.2.11. String comparision</a></span></dt><dt><span class="section"><a href="#wildcard">33.2.12. Wildcard Matching</a></span></dt><dt><span class="section"><a href="#mk-xterm-io">33.2.13. XTerm</a></span></dt><dt><span class="section"><a href="#stdio">33.2.14. Standard file input and output</a></span></dt><dt><span class="section"><a href="#errno">33.2.15. Error handling</a></span></dt><dt><span class="section"><a href="#misc">33.2.16. Miscellanea</a></span></dt></dl></dd><dt><span class="section"><a href="#i18n-mod">33.3. Internationalization of User Programs</a></span></dt><dd><dl><dt><span class="section"><a href="#ggettext">33.3.1. The GNU gettext</a></span></dt><dt><span class="section"><a href="#i18n-locale">33.3.2. Locale</a></span></dt></dl></dd><dt><span class="section"><a href="#regexp-mod">33.4. POSIX Regular Expressions</a></span></dt><dt><span class="section"><a href="#readline-mod">33.5. Advanced Readline and History Functionality</a></span></dt><dt><span class="section"><a href="#gdbm">33.6. GDBM - The GNU database manager</a></span></dt><dt><span class="section"><a href="#berkeley-db">33.7. Berkeley DB access</a></span></dt><dd><dl><dt><span class="section"><a href="#bdb-objects">33.7.1. Berkeley-DB Objects</a></span></dt><dt><span class="section"><a href="#bdb-close">33.7.2. Closing handles</a></span></dt><dt><span class="section"><a href="#bdb-db-environment">33.7.3. Database Environment</a></span></dt><dt><span class="section"><a href="#bdb-environment-config">33.7.4. Environment Configuration</a></span></dt><dt><span class="section"><a href="#bdb-operations">33.7.5. Database Operations</a></span></dt><dt><span class="section"><a href="#bdb-db-config">33.7.6. Database Configuration</a></span></dt><dt><span class="section"><a href="#bdb-cursor">33.7.7. Database Cursor Operations</a></span></dt><dt><span class="section"><a href="#bdb-lock">33.7.8. Lock Subsystem</a></span></dt><dt><span class="section"><a href="#bdb-log">33.7.9. Log Subsystem</a></span></dt><dt><span class="section"><a href="#bdb-mem-pool">33.7.10. Memory Pool Subsystem</a></span></dt><dt><span class="section"><a href="#bdb-replication">33.7.11. Replication</a></span></dt><dt><span class="section"><a href="#bdb-sequences">33.7.12. Sequences</a></span></dt><dt><span class="section"><a href="#bdb-transaction">33.7.13. Transaction Subsystem</a></span></dt></dl></dd><dt><span class="section"><a href="#dir-key">33.8. Directory Access</a></span></dt><dt><span class="section"><a href="#postgresql">33.9. PostgreSQL Database Access</a></span></dt><dt><span class="section"><a href="#oracle">33.10. Oracle Interface</a></span></dt><dd><dl><dt><span class="section"><a href="#ora-functionality">33.10.1. Functions and Macros in   package <strong class="package"><span class="quote">“<span class="quote">ORACLE</span>”</span></strong></a></span></dt><dt><span class="section"><a href="#ora-example">33.10.2. Oracle Example</a></span></dt><dt><span class="section"><a href="#ora-config">33.10.3. Oracle Configuration</a></span></dt><dt><span class="section"><a href="#ora-build">33.10.4. Building the Oracle Interface</a></span></dt></dl></dd><dt><span class="section"><a href="#libsvm">33.11. LibSVM Interface</a></span></dt><dd><dl><dt><span class="section"><a href="#libsvm-types">33.11.1. Types</a></span></dt><dt><span class="section"><a href="#libsvm-output">33.11.2. Output</a></span></dt><dt><span class="section"><a href="#libsvm-functions">33.11.3. Functions</a></span></dt></dl></dd><dt><span class="section"><a href="#pari">33.12. Computer Algebra System PARI</a></span></dt><dt><span class="section"><a href="#matlab">33.13. Matlab Interface</a></span></dt><dt><span class="section"><a href="#netica">33.14. Netica Interface</a></span></dt><dt><span class="section"><a href="#pcre">33.15. Perl Compatible Regular Expressions</a></span></dt><dt><span class="section"><a href="#zlib">33.16. Interface to zlib</a></span></dt><dt><span class="section"><a href="#rawsock">33.17. Raw Socket Access</a></span></dt><dd><dl><dt><span class="section"><a href="#rawsock-intro">33.17.1. Introduction</a></span></dt><dt><span class="section"><a href="#rawsock-func">33.17.2. Single System Call Functions</a></span></dt><dt><span class="section"><a href="#rawsock-args">33.17.3. Common arguments</a></span></dt><dt><span class="section"><a href="#rawsock-return">33.17.4. Return Values</a></span></dt><dt><span class="section"><a href="#rawsock-not-implemented">33.17.5. Not Implemented</a></span></dt><dt><span class="section"><a href="#rawsock-errors">33.17.6. Errors</a></span></dt><dt><span class="section"><a href="#rawsock-high-level">33.17.7. High-Level Functions</a></span></dt></dl></dd><dt><span class="section"><a href="#fastcgi">33.18. The FastCGI Interface</a></span></dt><dd><dl><dt><span class="section"><a href="#fcgi-overview">33.18.1. Overview of FastCGI</a></span></dt><dt><span class="section"><a href="#fcgi-functionality">33.18.2. Functions in Package <strong class="package"><span class="quote">“<span class="quote">FASTCGI</span>”</span></strong></a></span></dt><dt><span class="section"><a href="#fcgi-example">33.18.3. FastCGI Example</a></span></dt><dt><span class="section"><a href="#fcgi-build">33.18.4. Building and configuring the   FastCGI Interface</a></span></dt></dl></dd><dt><span class="section"><a href="#dbus">33.19. Interface to D-Bus</a></span></dt><dt><span class="section"><a href="#gtk">33.20. GTK Interface</a></span></dt><dd><dl><dt><span class="section"><a href="#gtk-hi">33.20.1. High-level functions</a></span></dt></dl></dd></dl></dd></dl></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="ext-p-indep"></a>Chapter 31. Platform Independent Extensions</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#custom-init-fini">31.1. Customizing <span class="command"><strong>CLISP</strong></span> Process   Initialization and Termination</a></span></dt><dd><dl><dt><span class="section"><a href="#cradle-grave">31.1.1. Cradle to Grave</a></span></dt><dt><span class="section"><a href="#init-hooks">31.1.2. Customizing Initialization</a></span></dt><dd><dl><dt><span class="section"><a href="#init-hooks-function">31.1.2.1. The difference between   <code class="varname">CUSTOM:*INIT-HOOKS*</code> and init function</a></span></dt></dl></dd><dt><span class="section"><a href="#fini-hooks">31.1.3. Customizing Termination</a></span></dt></dl></dd><dt><span class="section"><a href="#image">31.2. Saving an Image</a></span></dt><dd><dl><dt><span class="section"><a href="#image-portability">31.2.1. Image Portability</a></span></dt></dl></dd><dt><span class="section"><a href="#quit">31.3. Quitting <span class="command"><strong>CLISP</strong></span></a></span></dt><dt><span class="section"><a href="#i18n">31.4. Internationalization of <span class="command"><strong>CLISP</strong></span></a></span></dt><dd><dl><dt><span class="section"><a href="#language">31.4.1. The Language</a></span></dt></dl></dd><dt><span class="section"><a href="#encoding">31.5. Encodings</a></span></dt><dd><dl><dt><span class="section"><a href="#encodings-intro">31.5.1. Introduction</a></span></dt><dt><span class="section"><a href="#charset">31.5.2. Character Sets</a></span></dt><dt><span class="section"><a href="#newline">31.5.3. Line Terminators</a></span></dt><dt><span class="section"><a href="#make-encoding">31.5.4. Function <code class="function">EXT:MAKE-ENCODING</code></a></span></dt><dt><span class="section"><a href="#enc-charset">31.5.5. Function <code class="function">EXT:ENCODING-CHARSET</code></a></span></dt><dt><span class="section"><a href="#enc-dflt">31.5.6. Default encodings</a></span></dt><dd><dl><dt><span class="section"><a href="#line-term-default">31.5.6.1. Default line terminator</a></span></dt></dl></dd><dt><span class="section"><a href="#string-byte">31.5.7. Converting between strings and byte vectors</a></span></dt></dl></dd><dt><span class="section"><a href="#gstream">31.6. Generic streams</a></span></dt><dt><span class="section"><a href="#weak">31.7. Weak Objects</a></span></dt><dd><dl><dt><span class="section"><a href="#weak-pointer">31.7.1. Weak Pointers</a></span></dt><dt><span class="section"><a href="#weak-list">31.7.2. Weak Lists</a></span></dt><dt><span class="section"><a href="#weak-and-relation">31.7.3. Weak <span class="quote">“<span class="quote">And</span>”</span> Relations</a></span></dt><dt><span class="section"><a href="#weak-or-relation">31.7.4. Weak <span class="quote">“<span class="quote">Or</span>”</span> Relations</a></span></dt><dt><span class="section"><a href="#weak-mapping">31.7.5. Weak Associations</a></span></dt><dt><span class="section"><a href="#weak-and-mapping">31.7.6. Weak <span class="quote">“<span class="quote">And</span>”</span> Mappings</a></span></dt><dt><span class="section"><a href="#weak-or-mapping">31.7.7. Weak <span class="quote">“<span class="quote">Or</span>”</span> Mappings</a></span></dt><dt><span class="section"><a href="#weak-alist">31.7.8. Weak Association Lists</a></span></dt><dt><span class="section"><a href="#weak-ht">31.7.9. Weak Hash Tables</a></span></dt></dl></dd><dt><span class="section"><a href="#final">31.8. Finalization</a></span></dt><dt><span class="section"><a href="#prompt">31.9. The Prompt</a></span></dt><dt><span class="section"><a href="#ansi">31.10. Maximum ANSI CL compliance</a></span></dt><dt><span class="section"><a href="#macros3">31.11. Additional Fancy Macros and Functions</a></span></dt><dd><dl><dt><span class="section"><a href="#ethe">31.11.1. Macro <code class="function">EXT:ETHE</code></a></span></dt><dt><span class="section"><a href="#letf">31.11.2. Macros <code class="function">EXT:LETF</code> &amp; <code class="function">EXT:LETF*</code></a></span></dt><dt><span class="section"><a href="#memoized">31.11.3. Macro <code class="function">EXT:MEMOIZED</code></a></span></dt><dt><span class="section"><a href="#with-collect">31.11.4. Macro <code class="function">EXT:WITH-COLLECT</code></a></span></dt><dt><span class="section"><a href="#compile-time-value">31.11.5. Macro <code class="function">EXT:COMPILE-TIME-VALUE</code></a></span></dt><dt><span class="section"><a href="#with-gensyms">31.11.6. Macro <code class="function">EXT:WITH-GENSYMS</code></a></span></dt><dt><span class="section"><a href="#remove-plist">31.11.7. Function <code class="function">EXT:REMOVE-PLIST</code></a></span></dt><dt><span class="section"><a href="#html-http-output">31.11.8. Macros <code class="function">EXT:WITH-HTML-OUTPUT</code> and   <code class="function">EXT:WITH-HTTP-OUTPUT</code></a></span></dt><dt><span class="section"><a href="#open-http">31.11.9. Function <code class="function">EXT:OPEN-HTTP</code> and   macro <code class="function">EXT:WITH-HTTP-INPUT</code></a></span></dt><dt><span class="section"><a href="#http-log-stream">31.11.10. Variable <code class="varname">CUSTOM:*HTTP-LOG-STREAM*</code></a></span></dt><dt><span class="section"><a href="#browse-url">31.11.11. Function <code class="function">EXT:BROWSE-URL</code></a></span></dt><dt><span class="section"><a href="#http-proxy">31.11.12. Variable <code class="varname">CUSTOM:*HTTP-PROXY*</code></a></span></dt><dt><span class="section"><a href="#canonicalize">31.11.13. Function <code class="function">EXT:CANONICALIZE</code></a></span></dt></dl></dd><dt><span class="section"><a href="#customize">31.12. Customizing <span class="command"><strong>CLISP</strong></span> behavior</a></span></dt><dt><span class="section"><a href="#code-walk">31.13. Code Walker</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="custom-init-fini"></a>31.1. Customizing <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> Process
  Initialization and Termination</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#cradle-grave">31.1.1. Cradle to Grave</a></span></dt><dt><span class="section"><a href="#init-hooks">31.1.2. Customizing Initialization</a></span></dt><dd><dl><dt><span class="section"><a href="#init-hooks-function">31.1.2.1. The difference between   <code class="varname">CUSTOM:*INIT-HOOKS*</code> and init function</a></span></dt></dl></dd><dt><span class="section"><a href="#fini-hooks">31.1.3. Customizing Termination</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="cradle-grave"></a>31.1.1. Cradle to Grave</h3></div><div><h4 class="subtitle">What is done when</h4></div></div></div><div class="procedure"><ol class="procedure" type="1"><li class="step"><p class="title"><strong>Initialization</strong></p><ol type="a" class="substeps"><li class="step"><p>Parse command line arguments until the first
    positional argument (see <a href="impnotes.html#image-script" class="olink"><code class="constant">:SCRIPT</code></a>).</p></li><li class="step"><p>Load the <a href="impnotes.html#image" class="olink">memory image</a>.</p></li><li class="step"><p>Install internal signal handlers.</p></li><li class="step"><p>Initialize time variables.</p></li><li class="step"><p>Initialize <a class="link" href="#enc-dflt" title="31.5.6. Default encodings">locale-dependent
     encodings</a>.</p></li><li class="step"><p>Initialize stream variables.</p></li><li class="step"><p>Initialize pathname variables.</p></li><li class="step"><p>Initialize <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>.</p></li><li class="step"><p><a class="link" href="#modinit" title="32.2.2. Module initialization">Initialize
     modules</a>.</p></li><li class="step"><p>Run all functions in <a href="impnotes.html#init-hooks" class="olink"><code class="varname">CUSTOM:*INIT-HOOKS*</code></a>.</p></li><li class="step"><p>Say <span class="quote">“<span class="quote">hi</span>”</span>, unless suppressed by <code class="option"><a href="clisp.html#opt-verbose" class="olink">-q</a></code>.
  </p></li><li class="step"><p>Load <a href="clisp.html#opt-norc" class="olink">RC file</a>, unless suppressed by
    <code class="option"><a href="clisp.html#opt-norc" class="olink">-norc</a></code>.</p></li></ol></li><li class="step"><p class="title"><strong>The actual work</strong></p><p>Handle command line options: file
  <a href="clisp.html#opt-init" class="olink">loading</a> and/or
  <a href="clisp.html#opt-compile" class="olink">compilation</a>,
  <a href="clisp.html#opt-exec-expr" class="olink">form evaluation</a>,
  <a href="clisp.html#opt-exec-file" class="olink">script</a> execution, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-1.html">read-eval-print loop</a>.</p></li><li class="step"><p class="title"><strong>Finalization (executed even on abnormal exit due
  to <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/kill.html"><code class="function">kill</code></a>)</strong></p><ol type="a" class="substeps"><li class="step"><p>Unwind the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>, executing cleanup forms in
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_unwind-protect.html" target="_top"><code class="function">UNWIND-PROTECT</code></a>.</p></li><li class="step"><p>Run all functions in <a class="link" href="#fini-hooks" title="31.1.3. Customizing Termination"><code class="varname">CUSTOM:*FINI-HOOKS*</code></a>.</p></li><li class="step"><p>Call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_terpricm_fresh-line.html" target="_top"><code class="function">FRESH-LINE</code></a> on the standard streams.</p></li><li class="step"><p>Say <span class="quote">“<span class="quote">bye</span>”</span> unless suppressed by <code class="option"><a href="clisp.html#opt-verbose" class="olink">-q</a></code>.
  </p></li><li class="step"><p>Wait for a keypress if requested by
    <code class="option"><a href="clisp.html#opt-wait" class="olink">-w</a></code>.
  </p></li><li class="step"><p>Close all open <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_file-stream.html" target="_top"><code class="classname">FILE-STREAM</code></a>s.</p></li><li class="step"><p><a class="link" href="#modfini" title="32.2.3. Module finalization">Finalize
     modules</a>.</p></li><li class="step"><p>Close all open DLLs.</p></li></ol></li></ol></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="init-hooks"></a>31.1.2. Customizing Initialization</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#init-hooks-function">31.1.2.1. The difference between   <code class="varname">CUSTOM:*INIT-HOOKS*</code> and init function</a></span></dt></dl></div><p><a href="impnotes.html#init-hooks" class="olink"><code class="varname">CUSTOM:*INIT-HOOKS*</code></a> is run like this:</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_ignore-errors.html" target="_top"><code class="function">IGNORE-ERRORS</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_mapccm_ma_istcm_mapcon.html" target="_top"><code class="function">MAPC</code></a> #'<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_funcall.html" target="_top"><code class="function">FUNCALL</code></a> <a href="impnotes.html#init-hooks" class="olink"><code class="varname">CUSTOM:*INIT-HOOKS*</code></a>))
</pre><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="init-hooks-function"></a>31.1.2.1. The difference between
  <a href="impnotes.html#init-hooks" class="olink"><code class="varname">CUSTOM:*INIT-HOOKS*</code></a> and <a href="impnotes.html#init-func" class="olink">init function</a></h4></div></div></div><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a href="impnotes.html#init-hooks" class="olink"><code class="varname">CUSTOM:*INIT-HOOKS*</code></a> are
    <span class="emphasis"><em>always</em></span> run regardless of the command line
    options before even the banner is printed.</li><li class="listitem">The <a href="impnotes.html#init-func" class="olink">init function</a> is run <span class="emphasis"><em>only</em></span>
    if the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-1.html">read-eval-print loop</a> is ever entered and just before the
    first <a class="link" href="#prompt" title="31.9. The Prompt">prompt</a> is printed.
</li></ul></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="fini-hooks"></a>31.1.3. Customizing Termination</h3></div></div></div><p><a class="link" href="#fini-hooks" title="31.1.3. Customizing Termination"><code class="varname">CUSTOM:*FINI-HOOKS*</code></a> is run like this:</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_mapccm_ma_istcm_mapcon.html" target="_top"><code class="function">MAPC</code></a> #'<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_funcall.html" target="_top"><code class="function">FUNCALL</code></a> <a class="link" href="#fini-hooks" title="31.1.3. Customizing Termination"><code class="varname">CUSTOM:*FINI-HOOKS*</code></a>)
</pre></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="image"></a>31.2. Saving an Image</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#image-portability">31.2.1. Image Portability</a></span></dt></dl></div><p>The function <code class="code">(<a href="impnotes.html#image" class="olink"><code class="function">EXT:SAVEINITMEM</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
  (<em class="replaceable"><code>filename</code></em> "lispinit.mem") <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :KEEP-GLOBAL-HANDLERS :QUIET
  :INIT-FUNCTION :LOCKED-PACKAGES :START-PACKAGE :EXECUTABLE :NORC
  :SCRIPT :DOCUMENTATION :VERBOSE)</code>
 saves the running <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>'s memory to the file <em class="replaceable"><code>filename</code></em>;
 extension <code class="filename">#P".mem"</code> is recommended (when <em class="replaceable"><code>filename</code></em> does not have an
 extension, <code class="filename">#P".mem"</code> extension is automatically added unless the file
 being created is an executable).
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:QUIET</code></span></dt><dd><p class="simpara">If this argument is not <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the startup banner
    and the good-bye message will be suppressed, as if by <code class="option"><a href="clisp.html#opt-verbose" class="olink">-q</a></code>.</p><p class="simpara">This is <span class="strong"><strong>not</strong></span> recommended for interactive application delivery,
    please <span class="emphasis"><em>append</em></span> your banner to ours (using
    <a href="impnotes.html#init-func" class="olink">init function</a>) instead of <span class="emphasis"><em>replacing</em></span> it.
 </p></dd><dt><span class="term"><code class="constant">:VERBOSE</code></span></dt><dd>Print a message after writing the file.
    This argument defaults to <a href="impnotes.html#image" class="olink"><code class="varname">CUSTOM:*SAVEINITMEM-VERBOSE*</code></a>; initial value is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.
 </dd><dt><span class="term"><code class="constant">:NORC</code></span></dt><dd>If this argument is not <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the <a href="clisp.html#opt-norc" class="olink">RC file</a>
    loading will be suppressed, as if by <code class="option"><a href="clisp.html#opt-norc" class="olink">-norc</a></code>.
 </dd><dt><a id="init-func"></a><span class="term"><code class="constant">:INIT-FUNCTION</code></span></dt><dd><p class="simpara">This argument specifies a function that will be
   executed at startup of the saved image, before entering the standard <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-1.html">read-eval-print loop</a>
   (but after all other initialization, see <a class="xref" href="#cradle-grave" title="31.1.1. Cradle to Grave">Section 31.1.1, “Cradle to Grave”</a>);
   thus, if you want to avoid the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-1.html">read-eval-print loop</a>, you have to call <a class="link" href="#quit" title="31.3. Quitting CLISP"><code class="function">EXT:EXIT</code></a> at the
   end of the init function yourself
   (this does not prevent <a class="link" href="#fini-hooks" title="31.1.3. Customizing Termination"><code class="varname">CUSTOM:*FINI-HOOKS*</code></a> from being run).</p><p class="simpara">See <a href="clisp.html#opt-exec-file" class="olink">the
     manual</a> for passing command line arguments to this function.
   </p><p class="simpara">See also <a href="impnotes.html#init-hooks" class="olink"><code class="varname">CUSTOM:*INIT-HOOKS*</code></a> and <a class="link" href="#fini-hooks" title="31.1.3. Customizing Termination"><code class="varname">CUSTOM:*FINI-HOOKS*</code></a>.</p></dd><dt><a id="image-script"></a><span class="term"><a href="impnotes.html#image-script" class="olink"><code class="constant">:SCRIPT</code></a></span></dt><dd><p>This options determines the handling of positional
    arguments when the image is invoked.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">If it is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>, then the first positional argument
       is the script name and the rest is placed into <a href="impnotes.html#script-exec" class="olink"><code class="varname">EXT:*ARGS*</code></a>, as described
       in <a class="xref" href="#quickstart-unix" title="32.6.2. Scripting with CLISP">Section 32.6.2, “Scripting with <span class="command"><strong>CLISP</strong></span>”</a>.</li><li class="listitem">It it is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, then all positional arguments
       are placed into <a href="impnotes.html#script-exec" class="olink"><code class="varname">EXT:*ARGS*</code></a> to be handled by the <a href="impnotes.html#init-func" class="olink">init function</a>.
     </li></ul></div><p>
    This option defaults to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> when <a href="impnotes.html#init-func" class="olink">init function</a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and to
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> when <a href="impnotes.html#init-func" class="olink">init function</a> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
 </p></dd><dt><a id="image-doc"></a><span class="term"><code class="constant">:DOCUMENTATION</code></span></dt><dd><p class="simpara">The description of what this image does, printed
    by the <code class="option"><a href="clisp.html#opt-help-image" class="olink">-help-image</a></code> olption.</p><p class="simpara">Defaults to <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_doc_umentationcp.html" target="_top"><code class="function">DOCUMENTATION</code></a> <a href="impnotes.html#init-func" class="olink">init function</a>
     '<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_doc_umentationcp.html" target="_top"><code class="function">FUNCTION</code></a>)</code></p></dd><dt><span class="term"><code class="constant">:LOCKED-PACKAGES</code></span></dt><dd>This argument specifies the packages to lock before
   saving the image; this is convenient for application delivery, when
   you do not want your users to mess up your product.
   This argument defaults to <a class="link" href="#pack-lock" title="11.2. Constraints on the “COMMON-LISP” Package for Conforming Programs - package locking sec_11-1-2-1-2"><code class="varname">CUSTOM:*SYSTEM-PACKAGE-LIST*</code></a>.
 </dd><dt><span class="term"><code class="constant">:START-PACKAGE</code></span></dt><dd>This argument specifies the starting value of
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stpackagest.html" target="_top"><code class="varname">*PACKAGE*</code></a> in the image being saved, and defaults to the current
   value of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stpackagest.html" target="_top"><code class="varname">*PACKAGE*</code></a>.</dd><dt><span class="term"><code class="constant">:KEEP-GLOBAL-HANDLERS</code></span></dt><dd><p>When non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the currently established global
    handlers (either with <a href="impnotes.html#global-handler" class="olink"><code class="function">EXT:SET-GLOBAL-HANDLER</code></a> or with <code class="option"><a href="clisp.html#opt-on-error" class="olink">-on-error</a></code>)
    are inherited by the image.  Defaults to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, so that
    </p><pre class="screen"><strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp.html#clisp" class="olink">clisp</a></strong></span> <code class="option"><a href="clisp.html#opt-init" class="olink">-i</a></code> myfile <code class="option"><a href="clisp.html#opt-exec-expr" class="olink">-x</a></code> '(<a href="impnotes.html#image" class="olink"><code class="function">EXT:SAVEINITMEM</code></a>)'</pre><p>
    will produce an image without any global handlers inherited
    from the batch mode of the above command.</p></dd><dt><a id="image-exec"></a><span class="term"><code class="constant">:EXECUTABLE</code></span></dt><dd><p class="simpara">When non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the saved file will be a
    standalone executable.
    In this case, the <code class="filename">#P".mem"</code> extension is not added.
    On <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> and <a class="ulink" href="http://cygwin.com/" target="_top"><span class="platform">Cygwin</span></a> the extension <code class="filename">#P".exe"</code>
    is added instead.</p><p>Additionally, if this argument is <code class="literal">0</code>, the standard
    <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> command line options will <span class="strong"><strong>not</strong></span> be processed by the
    executable but will be placed into <a href="impnotes.html#script-exec" class="olink"><code class="varname">EXT:*ARGS*</code></a> instead.
    This is convenient for application delivery, so that your
    <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>-based application can accept, e.g., <code class="option"><a href="clisp.html#opt-exec-expr" class="olink">-x</a></code>.
    To override this feature of the image, you have to prefix the
    options with <code class="literal">"--clisp"</code>, e.g.,
    use <code class="option">--clisp-x</code> instead of <code class="option"><a href="clisp.html#opt-exec-expr" class="olink">-x</a></code>.
    This, given such a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>-based application, you can get to an
    ordinary <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-1.html">read-eval-print loop</a> by doing </p><pre class="screen">
<strong><code class="prompt">$</code></strong> application --clisp-x '(<a href="impnotes.html#image" class="olink"><code class="function">EXT:SAVEINITMEM</code></a> "myclisp" :executable t :init-function nil)'
<strong><code class="prompt">$</code></strong> ./myclisp
[1]&gt; (<a class="link" href="#factorial" title="Function EXT:!">!</a> 20)
2432902008176640000</pre><p>
    These instructions are also printed by
    <code class="option">--clisp--help</code>.</p><p class="simpara">Of course, this feature opens a <span class="emphasis"><em>security hole</em></span>
    if the application is running <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/setuid.html"><code class="function">setuid</code></a> root,
    therefore <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> resets the effective group and user IDs to the real
    ones if it sees a <code class="literal">"--clisp-*"</code> option.
</p></dd></dl></div><p>
You can use this memory image with the <code class="option"><a href="clisp.html#opt-memfile" class="olink">-M</a></code> option.
On <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> systems, you may compress it with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gzip.org/" target="_top"><span class="command"><strong>gzip</strong></span></a> to save disk
space.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="image-portability"></a>31.2.1. Image Portability</h3></div></div></div><p>Memory images are <span class="strong"><strong>not</strong></span> portable across different platforms
  (in contrast with platform-independent <code class="filename">#P".fas"</code> files).
  They are <span class="strong"><strong>not</strong></span> even portable across <a href="impnotes.html#linkset" class="olink">linking set</a>s: image saved using
  the <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>full</strong></span></a> <a href="impnotes.html#linkset" class="olink">linking set</a> cannot be used with the <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>base</strong></span></a> <a href="clisp.html#runtime" class="olink">runtime</a>:</p><pre class="screen">
<strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp.html#clisp" class="olink">clisp</a></strong></span> <code class="option"><a href="clisp.html#opt-link-set" class="olink">-K</a></code> full <code class="option"><a href="clisp.html#opt-exec-expr" class="olink">-x</a></code> '(<a href="impnotes.html#image" class="olink"><code class="function">EXT:SAVEINITMEM</code></a>)'
<strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp.html#clisp" class="olink">clisp</a></strong></span> <code class="option"><a href="clisp.html#opt-link-set" class="olink">-K</a></code> base <code class="option"><a href="clisp.html#opt-memfile" class="olink">-M</a></code> lispinit.mem
base/lisp.run: initialization file `lispinit.mem' was not created by this version of CLISP runtime</pre><p>
See also <a class="gmane" href="http://article.gmane.org/gmane.lisp.clisp.devel/17757"><code>Gmane/devel/17757</code></a>/<a class="ulink" href="https://sourceforge.net/p/clisp/mailman/message/18854510/" target="_top">https://sourceforge.net/p/clisp/mailman/message/18854510/</a>.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="quit"></a>31.3. Quitting <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a></h2></div></div></div><p>The functions </p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="code">(<a class="link" href="#quit" title="31.3. Quitting CLISP"><code class="function">EXT:EXIT</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>status</code></em>)</code></td></tr><tr><td><code class="code">(EXT:QUIT <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>status</code></em>)</code></td></tr><tr><td><code class="code">(EXT:BYE <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>status</code></em>)</code></td></tr></table><p>
 - all synonymous - terminate <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.  If <em class="replaceable"><code>status</code></em> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>,
 <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> aborts with the supplied numeric error <em class="replaceable"><code>status</code></em>, i.e.,
 the OS environment is informed that the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> session did not
 succeed.</p><p><a class="link" href="#fin-delim">Final delimiter</a>s also terminate
 <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="i18n"></a>31.4. Internationalization of <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#language">31.4.1. The Language</a></span></dt></dl></div><div class="variablelist"><p class="title"><strong>Glossary</strong></p><dl class="variablelist"><dt><span class="term">Internationalization (<span class="quote">“<span class="quote">i18n</span>”</span>)</span></dt><dd>preparing a program so that it can use multiple
    national languages and national cultural conventions without requiring
    further source code changes.</dd><dt><span class="term">Localization (<span class="quote">“<span class="quote">l10n</span>”</span>)</span></dt><dd>providing the data - mostly textual translations -
    necessary for an internationalized program to work in a particular
    language and with particular cultural conventions.
</dd></dl></div><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> is internationalized, and is localized for the languages
English, German, French, Spanish, Dutch, Russian, and Danish.
<a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> also supports internationalized Lisp programs, through
<a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/gettext/" target="_top">gettext</a>, see <a class="xref" href="#i18n-mod" title="33.3. Internationalization of User Programs">Section 33.3, “Internationalization of User Programs”</a>.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="language"></a>31.4.1. The Language</h3></div></div></div><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>The facilities described in this section will
  work only for the languages for which <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> itself is already
  localized.</p></div><p>The language <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> uses to communicate with the user can be one of
</p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="constant">ENGLISH</code></td></tr><tr><td><code class="constant">DEUTSCH</code> (i.e., German)</td></tr><tr><td><code class="constant">FRANÇAIS</code> (i.e., French)</td></tr><tr><td><code class="constant">ESPAÑOL</code> (i.e., Spanish)</td></tr><tr><td><code class="constant">NEDERLANDS</code> (i.e., Dutch)</td></tr><tr><td><code class="constant">РУССКИЙ</code>
  (i.e. Russian)</td></tr><tr><td><code class="constant">DANSK</code> (i.e., Danish)</td></tr></table><p>This is controlled by the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-symbol-macro.html"><code class="classname">SYMBOL-MACRO</code></a>
 <strong class="first"><em class="firstterm"><a href="impnotes.html#language" class="olink"><code class="varname">CUSTOM:*CURRENT-LANGUAGE*</code></a><a id="curr-lang" class="indexterm"></a></em></strong>,
 which can be set at run time as well as using the <code class="option"><a href="clisp.html#opt-lang" class="olink">-L</a></code> command line option.
 If you wish to change the
 <a href="clisp.html#opt-locale" class="olink">locale directory</a>
 at run time too, you can do that by setting <a href="impnotes.html#language" class="olink"><code class="varname">CUSTOM:*CURRENT-LANGUAGE*</code></a> to a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_cons.html" target="_top"><code class="classname">CONS</code></a>
 cell, whose <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CAR</code></a> is the language (a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>, one of the above),
 and whose <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDR</code></a> is the new locale directory.</p><p>More languages can be defined through the macro
 <strong class="first"><em class="firstterm"><a class="link" href="#deflang"><code class="function">I18N:DEFLANGUAGE</code></a><a id="deflang" class="indexterm"></a></em></strong>:
 <code class="code">(<a class="link" href="#deflang"><code class="function">I18N:DEFLANGUAGE</code></a> <em class="replaceable"><code>language</code></em>)</code>.
 For such an additional language to take effect, you must install the
 corresponding message catalog, or translate the messages yourself,
 using <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/gettext/" target="_top">gettext</a> and <a class="ulink" href="http://www.gnu.org/software/emacs/" target="_top">Emacs</a> <a class="" href="http://www.google.com/search?q=po-mode">po-mode</a>.</p><p>This works only for strings.  For arbitrary language-dependent
 Lisp objects, you define one through the macro
 <strong class="first"><em class="firstterm"><a class="link" href="#def-i-l"><code class="function">I18N:DEFINTERNATIONAL</code></a><a id="def-i-l" class="indexterm"></a></em></strong>:
 <code class="code">(<a class="link" href="#def-i-l"><code class="function">I18N:DEFINTERNATIONAL</code></a> <em class="replaceable"><code>symbol</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
 (<em class="replaceable"><code>default-language</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>))</code> and add
 language-dependent values through the macro
 <strong class="first"><em class="firstterm"><a class="link" href="#defloc"><code class="function">I18N:DEFLOCALIZED</code></a><a id="defloc" class="indexterm"></a></em></strong>:
 <code class="code">(<a class="link" href="#defloc"><code class="function">I18N:DEFLOCALIZED</code></a> <em class="replaceable"><code>symbol</code></em> <em class="replaceable"><code>language</code></em>
  <em class="replaceable"><code>value-form</code></em>)</code>
 (One such form for each language.  Languages without an assigned
 value will be treated like the default-language.)
 You can then access the localized value by calling
 <strong class="first"><em class="firstterm"><a class="link" href="#localized"><code class="function">I18N:LOCALIZED</code></a><a id="localized" class="indexterm"></a></em></strong>:
 <code class="code">(<a class="link" href="#localized"><code class="function">I18N:LOCALIZED</code></a> <em class="replaceable"><code>symbol</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>language</code></em>)</code></p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="encoding"></a>31.5. Encodings</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#encodings-intro">31.5.1. Introduction</a></span></dt><dt><span class="section"><a href="#charset">31.5.2. Character Sets</a></span></dt><dt><span class="section"><a href="#newline">31.5.3. Line Terminators</a></span></dt><dt><span class="section"><a href="#make-encoding">31.5.4. Function <code class="function">EXT:MAKE-ENCODING</code></a></span></dt><dt><span class="section"><a href="#enc-charset">31.5.5. Function <code class="function">EXT:ENCODING-CHARSET</code></a></span></dt><dt><span class="section"><a href="#enc-dflt">31.5.6. Default encodings</a></span></dt><dd><dl><dt><span class="section"><a href="#line-term-default">31.5.6.1. Default line terminator</a></span></dt></dl></dd><dt><span class="section"><a href="#string-byte">31.5.7. Converting between strings and byte vectors</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="encodings-intro"></a>31.5.1. Introduction</h3></div></div></div><p>An <span class="quote">“<span class="quote">encoding</span>”</span> describes the correspondence
 between <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>s and raw bytes during input/output via
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>.</p><p>An <a class="link" href="#encoding" title="31.5. Encodings"><code class="classname">EXT:ENCODING</code></a> is an object composed of the following facets:
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="link" href="#charset" title="31.5.2. Character Sets">character set</a></span></dt><dd>This denotes both the set of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>s that
    can be represented and passed through the I/O channel, and the way
    these characters translate into raw bytes, i.e., the map between
    sequences of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a> and <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span> in the form of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>s
    and <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8))</code></span> as well as character and byte <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s.
    In this context, for example, <a class="link" href="#charset-UTF-8"><code class="constant">CHARSET:UTF-8</code></a> and <a class="link" href="#charset-UCS-4"><code class="constant">CHARSET:UCS-4</code></a>
    are considered different, although they can represent the same set
    of characters.</dd><dt><span class="term"><a class="link" href="#newline" title="31.5.3. Line Terminators">line terminator</a> mode</span></dt><dd>This denotes the way newline characters are
    represented.</dd></dl></div><p><a class="link" href="#encoding" title="31.5. Encodings"><code class="classname">EXT:ENCODING</code></a>s are also <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_t.html" target="_top"><code class="literal">TYPE</code></a>s.  As such, they represent the set of
 characters encodable in the character set.  In this context, the way
 characters are translated into raw bytes is ignored, and the line
 terminator mode is ignored as well.  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_typep.html" target="_top"><code class="function">TYPEP</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_subtypep.html" target="_top"><code class="function">SUBTYPEP</code></a> can be used
 on encodings:</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_subtypep.html" target="_top"><code class="function">SUBTYPEP</code></a> <a class="link" href="#charset-UTF-8"><code class="constant">CHARSET:UTF-8</code></a> <a class="link" href="#charset-UTF-16"><code class="constant">CHARSET:UTF-16</code></a>)
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a></code> ;
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a></code>
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_subtypep.html" target="_top"><code class="function">SUBTYPEP</code></a> <a class="link" href="#charset-UTF-16"><code class="constant">CHARSET:UTF-16</code></a> <a class="link" href="#charset-UTF-8"><code class="constant">CHARSET:UTF-8</code></a>)
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a></code> ;
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a></code>
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_subtypep.html" target="_top"><code class="function">SUBTYPEP</code></a> CHARSET:ASCII CHARSET:ISO-8859-1)
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a></code> ;
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a></code>
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_subtypep.html" target="_top"><code class="function">SUBTYPEP</code></a> CHARSET:ISO-8859-1 CHARSET:ASCII)
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></code> ;
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a></code>
</pre><p><a id="enc1-1"></a><strong><span class="quote">“<span class="quote">1:1</span>”</span> encodings. </strong>Encodings which define a bijection between character and byte
 sequences are called <a class="link" href="#enc1-1" title="“1:1” encodings"><span class="quote">“<span class="quote">1:1</span>”</span> encoding</a>s. <a class="link" href="#charset-UTF-16"><code class="constant">CHARSET:ISO-8859-1</code></a> is an example of such an
 encoding: any byte sequence corresponds to some character sequence and
 vice versa.  <a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a>, however, is <span class="strong"><strong>not</strong></span> a <a class="link" href="#enc1-1" title="“1:1” encodings"><span class="quote">“<span class="quote">1:1</span>”</span> encoding</a>: there are no
 characters for bytes in the range [128;255]. <a class="link" href="#charset-UTF-8"><code class="constant">CHARSET:UTF-8</code></a> is <span class="strong"><strong>not</strong></span> a
 <a class="link" href="#enc1-1" title="“1:1” encodings"><span class="quote">“<span class="quote">1:1</span>”</span> encoding</a> either: some byte sequences do not correspond to any character
 sequence.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="charset"></a>31.5.2. Character Sets</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep">Only in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> built <span class="strong"><strong>without</strong></span> compile-time flag <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a></span></span></span></dt><dd>Only one character set is understood: the platform's
 native (8-bit) character set.  See <a class="xref" href="#characters" title="Chapter 13. Characters chap-13">Chapter 13, <em>Characters   chap-13</em></a>.
</dd><dt><a id="charset-symbols"></a><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep">Only in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> built <span class="strong"><strong>with</strong></span> compile-time flag <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a></span></span></span></dt><dd><p>The following character sets are supported, as values
 of the corresponding (constant) symbol in the <a class="link" href="#encoding" title="31.5. Encodings"><strong class="package"><span class="quote">“<span class="quote">CHARSET</span>”</span></strong></a> package:
</p><div class="orderedlist"><a id="charset-symbol-list"></a><p class="title"><strong>Symbols in package <a class="link" href="#encoding" title="31.5. Encodings"><strong class="package"><span class="quote">“<span class="quote">CHARSET</span>”</span></strong></a></strong></p><ol class="orderedlist" type="1"><li class="listitem"><a id="charset-UCS-2"></a><code class="constant">UCS-2</code>
   ≡ <code class="constant">UNICODE-16</code>
   ≡ <code class="constant">UNICODE-16-BIG-ENDIAN</code>,
   the 16-bit basic multilingual plane of the <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> character set.
   Every character is represented as two bytes.</li><li class="listitem"><a id="charset-UNICODE-16-LITTLE-ENDIAN"></a><code class="constant">UNICODE-16-LITTLE-ENDIAN</code>
    </li><li class="listitem"><a id="charset-UCS-4"></a><code class="constant">UCS-4</code>
   ≡ <code class="constant">UNICODE-32</code>
   ≡ <code class="constant">UNICODE-32-BIG-ENDIAN</code>,
   the 21-bit <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> character set. Every character is represented as
   four bytes. This encoding is used by <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> internally.</li><li class="listitem"><a id="charset-UNICODE-32-LITTLE-ENDIAN"></a><code class="constant">UNICODE-32-LITTLE-ENDIAN</code></li><li class="listitem"><a id="charset-UTF-8"></a><code class="constant">UTF-8</code>,
   the 21-bit <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> character set.
   Every character is represented as one to four bytes.
   <a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a> characters represent themselves and need one byte per character.
   Most Latin/Greek/Cyrillic/Hebrew characters need two bytes per
   character. Most other characters need three bytes per character,
   and the rarely used remaining characters need four bytes per
   character. This is therefore, in general, the most space-efficient
   encoding of all of Unicode.</li><li class="listitem"><a id="charset-UTF-16"></a><code class="constant">UTF-16</code>,
   the 21-bit <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> character set. Every character in the 16-bit
   basic multilingual plane is represented as two bytes, and the
   rarely used remaining characters need four bytes per character.
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-UTF-7"></a><code class="constant">UTF-7</code>,
   the 21-bit <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> character set. This is a stateful 7-bit encoding.
   Not all <a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a> characters represent themselves.
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-JAVA"></a><code class="constant">JAVA</code>,
   the 21-bit <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> character set.
   <a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a> characters represent themselves and need one byte per character.
   All other characters of the basic multilingual plane are represented
   by <code class="literal">\u<em class="replaceable"><code>nnnn</code></em></code> sequences
   (<em class="replaceable"><code>nnnn</code></em> a hexadecimal number)
   and need 6 bytes per character. The remaining characters are represented
   by <code class="literal">\u<em class="replaceable"><code>xxxx</code></em>\u<em class="replaceable"><code>yyyy</code></em></code>
   and need 12 bytes per character. While this encoding is very comfortable
   for editing Unicode files using only <a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a>-aware tools and editors, it
   cannot faithfully represent all <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> text. Only text which
   does not contain <code class="literal">\u</code> (backslash followed by
   lowercase Latin u) can be faithfully represented by this encoding.
 </li><li class="listitem"><a id="charset-ASCII"></a><code class="constant">ASCII</code>,
   the well-known US-centric 7-bit character set (American Standard
   Code for Information Interchange - <a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a>).</li><li class="listitem"><a id="charset-ISO-8859-1"></a><p class="simpara"><code class="constant">ISO-8859-1</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Afrikaans, Albanian, Basque, Breton, Catalan,
   Cornish, Danish, Dutch, English, Færoese, Finnish, French,
   Frisian, Galician, German, Greenlandic, Icelandic, Irish, Italian,
   Latin, Luxemburgish, Norwegian, Portuguese, Ræto-Romanic,
   Scottish, Spanish, and Swedish languages.</p><p>This encoding has the nice property that</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_loop.html" target="_top"><code class="function">LOOP</code></a> :for i :from 0 :to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_char-code-limit.html" target="_top"><code class="constant">CHAR-CODE-LIMIT</code></a> :for c = (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a> i)
  :always (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_or.html" target="_top"><code class="function">OR</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_not.html" target="_top"><code class="function">NOT</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_typep.html" target="_top"><code class="function">TYPEP</code></a> c CHARSET:ISO-8859-1))
              (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_equalp.html" target="_top"><code class="function">EQUALP</code></a> (<a class="link" href="#string-byte" title="31.5.7. Converting between strings and byte vectors"><code class="function">EXT:CONVERT-STRING-TO-BYTES</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_string.html" target="_top"><code class="function">STRING</code></a> c) CHARSET:ISO-8859-1)
                      (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_vector.html" target="_top"><code class="function">VECTOR</code></a> i))))
⇒ <code class="computeroutput">T</code></pre><p>
   i.e., it is compatible with <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_code-char.html" target="_top"><code class="function">CODE-CHAR</code></a>/<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_char-code.html" target="_top"><code class="function">CHAR-CODE</code></a>
   in its own domain.</p></li><li class="listitem"><a id="charset-ISO-8859-2"></a><code class="constant">ISO-8859-2</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Croatian, Czech, German, Hungarian, Polish,
   Slovak, Slovenian, and Sorbian languages. </li><li class="listitem"><a id="charset-ISO-8859-3"></a><code class="constant">ISO-8859-3</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Esperanto and Maltese languages.</li><li class="listitem"><a id="charset-ISO-8859-4"></a><code class="constant">ISO-8859-4</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Estonian, Latvian, Lithuanian and Sami (Lappish)
   languages.</li><li class="listitem"><a id="charset-ISO-8859-5"></a><code class="constant">ISO-8859-5</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Bulgarian, Byelorussian, Macedonian, Russian,
   Serbian, and Ukrainian languages.</li><li class="listitem"><a id="charset-ISO-8859-6"></a><code class="constant">ISO-8859-6</code>,
   suitable for the Arabic language.</li><li class="listitem"><a id="charset-ISO-8859-7"></a><code class="constant">ISO-8859-7</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Greek language.</li><li class="listitem"><a id="charset-ISO-8859-8"></a><code class="constant">ISO-8859-8</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Hebrew language (without punctuation).</li><li class="listitem"><a id="charset-ISO-8859-9"></a><code class="constant">ISO-8859-9</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Turkish language.</li><li class="listitem"><a id="charset-ISO-8859-10"></a><code class="constant">ISO-8859-10</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Estonian, Icelandic, Inuit (Greenlandic), Latvian,
   Lithuanian, and Sami (Lappish) languages.</li><li class="listitem"><a id="charset-ISO-8859-13"></a><code class="constant">ISO-8859-13</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Estonian, Latvian, Lithuanian, Polish and Sami
   (Lappish) languages.</li><li class="listitem"><a id="charset-ISO-8859-14"></a><code class="constant">ISO-8859-14</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Irish Gælic, Manx Gælic, Scottish
   Gælic, and Welsh languages.</li><li class="listitem"><a id="charset-ISO-8859-15"></a><code class="constant">ISO-8859-15</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the ISO-8859-1 languages, with improvements for
   French, Finnish and the Euro.</li><li class="listitem"><a id="charset-ISO-8859-16"></a><code class="constant">ISO-8859-16</code>
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Rumanian language.</li><li class="listitem"><a id="charset-KOI8-R"></a><code class="constant">KOI8-R</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Russian language (very popular, especially on the
   internet).</li><li class="listitem"><a id="charset-KOI8-U"></a><code class="constant">KOI8-U</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Ukrainian language (very popular, especially on the
   internet).</li><li class="listitem"><a id="charset-KOI8-RU"></a><code class="constant">KOI8-RU</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Russian language. This character set is only available on
                           platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><code class="constant">JIS_X0201</code>,
   a character set for the Japanese language.</li><li class="listitem"><a id="charset-MAC-ARABIC"></a><code class="constant">MAC-ARABIC</code>,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>.</li><li class="listitem"><a id="charset-MAC-CENTRAL-EUROPE"></a><code class="constant">MAC-CENTRAL-EUROPE</code>,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>.</li><li class="listitem"><a id="charset-MAC-CROATIAN"></a><code class="constant">MAC-CROATIAN</code>,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>.</li><li class="listitem"><a id="charset-MAC-CYRILLIC"></a><code class="constant">MAC-CYRILLIC</code>,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>.</li><li class="listitem"><a id="charset-MAC-DINGBAT"></a><code class="constant">MAC-DINGBAT</code>,
   a platform specific character set.</li><li class="listitem"><a id="charset-MAC-GREEK"></a><code class="constant">MAC-GREEK</code>,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>.</li><li class="listitem"><a id="charset-MAC-HEBREW"></a><code class="constant">MAC-HEBREW</code>,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>.</li><li class="listitem"><a id="charset-MAC-ICELAND"></a><code class="constant">MAC-ICELAND</code>,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>.</li><li class="listitem"><a id="charset-MAC-ROMAN"></a><code class="constant">MAC-ROMAN</code>
   ≡ <code class="constant">MACINTOSH</code>,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>.</li><li class="listitem"><a id="charset-MAC-ROMANIA"></a><code class="constant">MAC-ROMANIA</code>,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>.</li><li class="listitem"><a id="charset-MAC-SYMBOL"></a><code class="constant">MAC-SYMBOL</code>,
   a platform specific character set.</li><li class="listitem"><a id="charset-MAC-THAI"></a><code class="constant">MAC-THAI</code>,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>.</li><li class="listitem"><a id="charset-MAC-TURKISH"></a><code class="constant">MAC-TURKISH</code>,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>.</li><li class="listitem"><a id="charset-MAC-UKRAINE"></a><code class="constant">MAC-UKRAINE</code>,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>.</li><li class="listitem"><a id="charset-CP437"></a><code class="constant">CP437</code>, a DOS oldie,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>.</li><li class="listitem"><a id="charset-CP437-IBM"></a><code class="constant">CP437-IBM</code>,
   an IBM variant of <code class="constant">CP437</code>.</li><li class="listitem"><a id="charset-CP737"></a><code class="constant">CP737</code>, a DOS oldie,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, meant to be suitable for the Greek language.</li><li class="listitem"><a id="charset-CP775"></a><code class="constant">CP775</code>, a DOS oldie,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, meant to be suitable for some Baltic languages.</li><li class="listitem"><a id="charset-CP850"></a><code class="constant">CP850</code>, a DOS oldie,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>.</li><li class="listitem"><a id="charset-CP852"></a><code class="constant">CP852</code>, a DOS oldie,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>.</li><li class="listitem"><a id="charset-CP852-IBM"></a><code class="constant">CP852-IBM</code>,
   an IBM variant of <code class="constant">CP852</code>.</li><li class="listitem"><a id="charset-CP855"></a><code class="constant">CP855</code>, a DOS oldie,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, meant to be suitable for the Russian language.</li><li class="listitem"><a id="charset-CP857"></a><code class="constant">CP857</code>, a DOS oldie,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, meant to be suitable for the Turkish language.</li><li class="listitem"><a id="charset-CP860"></a><code class="constant">CP860</code>, a DOS oldie,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, meant to be suitable for the Portuguese language.</li><li class="listitem"><a id="charset-CP860-IBM"></a><code class="constant">CP860-IBM</code>,
   an IBM variant of <code class="constant">CP860</code>.</li><li class="listitem"><a id="charset-CP861"></a><code class="constant">CP861</code>, a DOS oldie,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, meant to be suitable for the Icelandic language.</li><li class="listitem"><a id="charset-CP861-IBM"></a><code class="constant">CP861-IBM</code>,
   an IBM variant of <code class="constant">CP861</code>.</li><li class="listitem"><a id="charset-CP862"></a><code class="constant">CP862</code>, a DOS oldie,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, meant to be suitable for the Hebrew language.</li><li class="listitem"><a id="charset-CP862-IBM"></a><code class="constant">CP862-IBM</code>,
   an IBM variant of <code class="constant">CP862</code>.</li><li class="listitem"><a id="charset-CP863"></a><code class="constant">CP863</code>, a DOS oldie,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>.</li><li class="listitem"><a id="charset-CP863-IBM"></a><code class="constant">CP863-IBM</code>,
   an IBM variant of <code class="constant">CP863</code>.</li><li class="listitem"><a id="charset-CP864"></a><code class="constant">CP864</code>, a DOS oldie,
   meant to be suitable for the Arabic language.</li><li class="listitem"><a id="charset-CP864-IBM"></a><code class="constant">CP864-IBM</code>,
   an IBM variant of <code class="constant">CP864</code>.
 </li><li class="listitem"><a id="charset-CP865"></a><code class="constant">CP865</code>, a DOS oldie,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, meant to be suitable for some Nordic languages.</li><li class="listitem"><a id="charset-CP865-IBM"></a><code class="constant">CP865-IBM</code>,
   an IBM variant of <code class="constant">CP865</code>.
 </li><li class="listitem"><a id="charset-CP866"></a><code class="constant">CP866</code>, a DOS oldie,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, meant to be suitable for the Russian language.</li><li class="listitem"><a id="charset-CP869"></a><code class="constant">CP869</code>, a DOS oldie,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, meant to be suitable for the Greek language.</li><li class="listitem"><a id="charset-CP869-IBM"></a><code class="constant">CP869-IBM</code>,
   an IBM variant of <code class="constant">CP869</code>.
 </li><li class="listitem"><a id="charset-CP874"></a><code class="constant">CP874</code>, a DOS oldie,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, meant to be suitable for the Thai language.</li><li class="listitem"><a id="charset-CP874-IBM"></a><code class="constant">CP874-IBM</code>,
   an IBM variant of <code class="constant">CP874</code>.
 </li><li class="listitem"><a id="charset-WINDOWS-1250"></a><code class="constant">WINDOWS-1250</code>
   ≡ <code class="constant">CP1250</code>,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, heavily incompatible with ISO-8859-2.
 </li><li class="listitem"><a id="charset-WINDOWS-1251"></a><code class="constant">WINDOWS-1251</code>
   ≡ <code class="constant">CP1251</code>,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, heavily incompatible with ISO-8859-5,
   meant to be suitable for the Russian language.</li><li class="listitem"><a id="charset-WINDOWS-1252"></a><code class="constant">WINDOWS-1252</code>
   ≡ <code class="constant">CP1252</code>,
   a platform specific extension of the ISO-8859-1 character set.
 </li><li class="listitem"><a id="charset-WINDOWS-1253"></a><code class="constant">WINDOWS-1253</code>
   ≡ <code class="constant">CP1253</code>,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, gratuitously incompatible with ISO-8859-7,
   meant to be suitable for the Greek language.</li><li class="listitem"><a id="charset-WINDOWS-1254"></a><code class="constant">WINDOWS-1254</code>
   ≡ <code class="constant">CP1254</code>,
   a platform specific extension of the ISO-8859-9 character set.
 </li><li class="listitem"><a id="charset-WINDOWS-1255"></a><code class="constant">WINDOWS-1255</code>
   ≡ <code class="constant">CP1255</code>,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, gratuitously incompatible with ISO-8859-8,
   suitable for the Hebrew language.
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-WINDOWS-1256"></a><code class="constant">WINDOWS-1256</code>
   ≡ <code class="constant">CP1256</code>,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, meant to be suitable for the Arabic language.</li><li class="listitem"><a id="charset-WINDOWS-1257"></a><code class="constant">WINDOWS-1257</code>
   ≡ <code class="constant">CP1257</code>,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>.</li><li class="listitem"><a id="charset-WINDOWS-1258"></a><code class="constant">WINDOWS-1258</code>
   ≡ <code class="constant">CP1258</code>, a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, meant to be suitable for the
   Vietnamese language. This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-HP-ROMAN8"></a><code class="constant">HP-ROMAN8</code>,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>.</li><li class="listitem"><a id="charset-NEXTSTEP"></a><code class="constant">NEXTSTEP</code>,
   a platform specific extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>.</li><li class="listitem"><a id="charset-EUC-JP"></a><code class="constant">EUC-JP</code>,
   a multibyte character set for the Japanese language.
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-SHIFT-JIS"></a><code class="constant">SHIFT-JIS</code>,
   a multibyte character set for the Japanese language.
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-CP932"></a><code class="constant">CP932</code>,
   a Microsoft variant of <code class="constant">SHIFT-JIS</code>.
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-ISO-2022-JP"></a><code class="constant">ISO-2022-JP</code>,
   a stateful 7-bit multibyte character set for the Japanese language.
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-ISO-2022-JP-2"></a><code class="constant">ISO-2022-JP-2</code>,
   a stateful 7-bit multibyte character set for the Japanese language.
   This character set is only available on platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> 2.3
   or newer or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-ISO-2022-JP-1"></a><code class="constant">ISO-2022-JP-1</code>,
   a stateful 7-bit multibyte character set for the Japanese language.
   This character set is only available on
                           platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-EUC-CN"></a><code class="constant">EUC-CN</code>,
   a multibyte character set for simplified Chinese.
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-HZ"></a><code class="constant">HZ</code>,
   a stateful 7-bit multibyte character set for simplified Chinese.
   This character set is only available on
                           platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-GBK"></a><code class="constant">GBK</code>,
   a multibyte character set for Chinese,
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-CP936"></a><code class="constant">CP936</code>,
   a Microsoft variant of <code class="constant">GBK</code>.
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-GB18030"></a><code class="constant">GB18030</code>,
   a multibyte character set for Chinese,
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-EUC-TW"></a><code class="constant">EUC-TW</code>,
   a multibyte character set for traditional Chinese.
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-BIG5"></a><code class="constant">BIG5</code>,
   a multibyte character set for traditional Chinese.
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-CP950"></a><code class="constant">CP950</code>,
   a Microsoft variant of <code class="constant">BIG5</code>.
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-BIG5-HKSCS"></a><code class="constant">BIG5-HKSCS</code>,
   a multibyte character set for traditional Chinese.
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-ISO-2022-CN"></a><code class="constant">ISO-2022-CN</code>,
   a stateful 7-bit multibyte character set for Chinese.
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-ISO-2022-CN-EXT"></a><code class="constant">ISO-2022-CN-EXT</code>,
   a stateful 7-bit multibyte character set for Chinese.
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-EUC-KR"></a><code class="constant">EUC-KR</code>,
   a multibyte character set for Korean.
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-CP949"></a><code class="constant">CP949</code>,
   a Microsoft variant of <code class="constant">EUC-KR</code>.
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-ISO-2022-KR"></a><code class="constant">ISO-2022-KR</code>,
   a stateful 7-bit multibyte character set for Korean.
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-JOHAB"></a><code class="constant">JOHAB</code>,
   a multibyte character set for Korean used mostly on <a class="ulink" href="http://www.freedos.org/" target="_top"><span class="platform">DOS</span></a>.
   This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-ARMSCII-8"></a><code class="constant">ARMSCII-8</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Armenian. This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-GEORGIAN-ACADEMY"></a><code class="constant">GEORGIAN-ACADEMY</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Georgian. This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-GEORGIAN-PS"></a><code class="constant">GEORGIAN-PS</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Georgian. This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-TIS-620"></a><code class="constant">TIS-620</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Thai. This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-MULELAO-1"></a><code class="constant">MULELAO-1</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Laotian. This character set is only available on
                           platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-CP1133"></a><code class="constant">CP1133</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Laotian. This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-VISCII"></a><code class="constant">VISCII</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Vietnamese. This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><a id="charset-TCVN"></a><code class="constant">TCVN</code>,
   an extension of the <a class="link" href="#charset-ASCII">ASCII character set</a>, suitable for the Vietnamese. This character set is only available on
                                 platforms with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>.</li><li class="listitem"><p><a id="base64"></a><code class="constant">BASE64</code>, encodes
  arbitrary byte sequences with 64 <a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a> characters </p><div class="literallayout"><p><br />
   ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/<br />
  </p></div><p> as specifined by <a class="rfc" href="http://www.ietf.org/rfc/rfc2045.txt"><code>MIME</code></a>; 3 bytes are encoded with 4
  characters, line breaks are inserted after every 76 characters.</p><p class="simpara">While this is not a traditional character set (i.e., it does
  not map a set of characters in a natural language into bytes), it
  does define a map between arbitrary byte sequences and certain
  character sequences, so it falls naturally into the <a class="link" href="#encoding" title="31.5. Encodings"><code class="classname">EXT:ENCODING</code></a> class.
</p></li></ol></div><p>


</p><div class="variablelist"><dl class="variablelist"><dt><a id="iconv"></a><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep">Only on <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> systems
  with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> 2.2 or better and other systems (<a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> and <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>)
  on which the <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a> <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> library has been installed</span></span></span></dt><dd><p class="simpara">The character sets provided by the library function
 <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/iconv.html"><code class="function">iconv</code></a> can also be used as encodings.  To create such an encoding,
 call <a class="link" href="#make-encoding" title="31.5.4. Function EXT:MAKE-ENCODING"><code class="function">EXT:MAKE-ENCODING</code></a> with the character set name (a string) as the
 <code class="constant">:CHARSET</code> argument.</p><p class="simpara">When an <a class="link" href="#encoding" title="31.5. Encodings"><code class="classname">EXT:ENCODING</code></a> is available both as a <a class="link" href="#charset-symbols">built-in</a> and
 through <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/iconv.html"><code class="function">iconv</code></a>, the <a class="link" href="#charset-symbols">built-in</a> is used, because it is more
 efficient and available across all platforms.</p><p class="simpara">These encodings are not assigned to global variables, since
 there is no portable way to get the list of all character sets
 supported by <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/iconv.html"><code class="function">iconv</code></a>.</p><p class="simpara">On standard-compliant <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> systems (e.g., <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> systems, such
 as <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a>/<a class="ulink" href="https://www.kernel.org/" target="_top"><span class="platform">Linux</span></a> and <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a>/<a class="ulink" href="http://www.gnu.org/software/hurd/" target="_top"><span class="platform">Hurd</span></a>) and on systems with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a> you
 get this list by calling the <span class="emphasis"><em>program</em></span>:
 <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/iconv.html"><span class="command"><strong>iconv -l</strong></span></a>.</p><p class="simpara">The reason we use only <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> 2.2 or <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a> is
 that the other <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/iconv.html"><code class="function">iconv</code></a> implementations are broken in various ways and
 we do not want to deal with random <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> crashes caused by those bugs.
 If your system supplies an <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/iconv.html"><code class="function">iconv</code></a> implementation which passes the
 <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libiconv/" target="_top">libiconv</a>'s test suite, please report that
 to <a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-list/">clisp-list</a> and a
 future <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> version will use <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/iconv.html"><code class="function">iconv</code></a> on your system.</p></dd></dl></div><p>

</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="newline"></a>31.5.3. Line Terminators</h3></div></div></div><p>The line terminator mode can be one of the following three keywords:
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:UNIX</code></span></dt><dd>Newline is represented by the <a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a>
   <span class="keycode">LF</span> character (<span class="keycode">U000A</span>).
</dd><dt><span class="term"><code class="constant">:MAC</code></span></dt><dd>Newline is represented by the <a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a>
   <span class="keycode">CR</span> character (<span class="keycode">U000D</span>).
</dd><dt><span class="term"><code class="constant">:DOS</code></span></dt><dd>Newline is represented by the <a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a>
   <span class="keycode">CR</span> followed by the <a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a> <span class="keycode">LF</span>.
</dd></dl></div><p>Windows programs typically use the <code class="constant">:DOS</code> line terminator,
 sometimes they also accept <code class="constant">:UNIX</code> line terminators or produce
 <code class="constant">:MAC</code> line terminators.</p><p>The <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> protocol also requires <code class="constant">:DOS</code> line terminators.</p><p>The line terminator mode is relevant only for output (writing to a
 <a class="link" href="#open" title="21.12. Function OPEN">file</a>/<a class="link" href="#pipe" title="32.7.2. Pipes">pipe</a>/<a class="link" href="#socket" title="32.4. Socket Streams">socket</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>).  During input, all three kinds of line terminators
 are recognized.  See also <a class="xref" href="#clhs-newline" title="13.11. Treatment of Newline during Input and Output sec_13-1-8">Section 13.11, “Treatment of Newline during Input and Output   sec_13-1-8”</a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="make-encoding"></a>31.5.4. Function <a class="link" href="#make-encoding" title="31.5.4. Function EXT:MAKE-ENCODING"><code class="function">EXT:MAKE-ENCODING</code></a></h3></div></div></div><p>The function <code class="code">(<a class="link" href="#make-encoding" title="31.5.4. Function EXT:MAKE-ENCODING"><code class="function">EXT:MAKE-ENCODING</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :CHARSET
     :LINE-TERMINATOR :INPUT-ERROR-ACTION :OUTPUT-ERROR-ACTION)</code>
 returns an <a class="link" href="#encoding" title="31.5. Encodings"><code class="classname">EXT:ENCODING</code></a>. The <code class="constant">:CHARSET</code> argument may be
 an encoding, a string, or <code class="constant">:DEFAULT</code>.
 The possible values for the <a class="link" href="#newline" title="31.5.3. Line Terminators">line terminator</a> argument are the
 keywords <code class="constant">:UNIX</code>, <code class="constant">:MAC</code>, <code class="constant">:DOS</code>.</p><p>The <code class="constant">:INPUT-ERROR-ACTION</code> argument specifies
 what happens when an invalid byte sequence is encountered while
 converting bytes to characters.  Its value can be <code class="constant">:ERROR</code>, <code class="constant">:IGNORE</code>
 or a character to be used instead.  The <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> character
 <span class="keysym">#\uFFFD</span> is typically used to indicate an error in the
 input sequence.</p><p>The <code class="constant">:OUTPUT-ERROR-ACTION</code> argument specifies
 what happens when an invalid character is encountered while converting
 characters to bytes.  Its value can be <code class="constant">:ERROR</code>, <code class="constant">:IGNORE</code>, a byte to
 be used instead, or a character to be used instead.  The <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a>
 character <span class="keysym">#\uFFFD</span> can be used here only if it is
 encodable in the character set.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="enc-charset"></a>31.5.5. Function <a class="link" href="#enc-charset" title="31.5.5. Function EXT:ENCODING-CHARSET"><code class="function">EXT:ENCODING-CHARSET</code></a></h3></div><div><h4 class="subtitle"><span class="plat-dep">Platform Dependent: <span class="plat-dep">Only in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> built <span class="strong"><strong>with</strong></span> compile-time flag <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a></span></span></h4></div></div></div><p>The function <code class="code">(<a class="link" href="#enc-charset" title="31.5.5. Function EXT:ENCODING-CHARSET"><code class="function">EXT:ENCODING-CHARSET</code></a> <em class="replaceable"><code>encoding</code></em>)</code> returns the
 charset of the <em class="replaceable"><code>encoding</code></em>, as a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a> or a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_string.html" target="_top"><code class="function">STRING</code></a> (<a class="link" href="#enc-charset" title="31.5.5. Function EXT:ENCODING-CHARSET"><code class="function">EXT:ENCODING-CHARSET</code></a> <em class="replaceable"><code>encoding</code></em>))</code> is
  not necessarily a valid <a class="rfc" href="http://www.ietf.org/rfc/rfc2045.txt"><code>MIME</code></a> name.</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="enc-dflt"></a>31.5.6. Default encodings</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#line-term-default">31.5.6.1. Default line terminator</a></span></dt></dl></div><p>Besides every <a class="link" href="#open" title="21.12. Function OPEN">file</a>/<a class="link" href="#pipe" title="32.7.2. Pipes">pipe</a>/<a class="link" href="#socket" title="32.4. Socket Streams">socket</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> containing an encoding,
 the following <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-symbol-macro.html"><code class="classname">SYMBOL-MACRO</code></a> places contain global <a class="link" href="#encoding" title="31.5. Encodings"><code class="classname">EXT:ENCODING</code></a>s:</p><p><a id="def-file-enc"></a><strong><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-symbol-macro.html"><code class="classname">SYMBOL-MACRO</code></a> <a href="impnotes.html#def-file-enc" class="olink"><code class="varname">CUSTOM:*DEFAULT-FILE-ENCODING*</code></a>. </strong>The <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-symbol-macro.html"><code class="classname">SYMBOL-MACRO</code></a> <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a> <a href="impnotes.html#def-file-enc" class="olink"><code class="varname">CUSTOM:*DEFAULT-FILE-ENCODING*</code></a> is the encoding used for
 new <a class="link" href="#open" title="21.12. Function OPEN">file</a>/<a class="link" href="#pipe" title="32.7.2. Pipes">pipe</a>/<a class="link" href="#socket" title="32.4. Socket Streams">socket</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>, when no <a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a> argument was specified.
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep">Only in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> built <span class="strong"><strong>with</strong></span> compile-time flag <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a></span></span></span></dt><dd><p class="simpara">The following are <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-symbol-macro.html"><code class="classname">SYMBOL-MACRO</code></a> places.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><strong class="first"><em class="firstterm"><a href="impnotes.html#path-enc" class="olink"><code class="varname">CUSTOM:*PATHNAME-ENCODING*</code></a>
   <a id="path-enc" class="indexterm"></a></em></strong></span></dt><dd><p>is the encoding used for converting filenames in the
   file system (represented with byte sequences by the OS) to lisp
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_pathname.html" target="_top"><code class="classname">PATHNAME</code></a> components (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>s).
   If this encoding is incompatible with some file names on your system,
   file system access (e.g., <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_directory.html" target="_top"><code class="function">DIRECTORY</code></a>) may <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>s,
   thus extreme caution is recommended if this is <span class="strong"><strong>not</strong></span> a <a class="link" href="#enc1-1" title="“1:1” encodings"><span class="quote">“<span class="quote">1:1</span>”</span> encoding</a>.
   Sometimes it may not be obvious that the encoding is involved at all.
   E.g., on <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>: </p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_parse-namestring.html" target="_top"><code class="function">PARSE-NAMESTRING</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_string.html" target="_top"><code class="function">STRING</code></a> #\ARMENIAN_SMALL_LETTER_RA))
*** - PARSE-NAMESTRING: syntax error in filename "ռ" at position 0
</pre><p>when <a href="impnotes.html#path-enc" class="olink"><code class="varname">CUSTOM:*PATHNAME-ENCODING*</code></a> is <a class="link" href="#charset-UTF-16"><code class="constant">CHARSET:UTF-16</code></a> because then
   <span class="data"><code class="literal">#\ARMENIAN_SMALL_LETTER_RA</code></span> corresponds
   to the 4 bytes <span class="data"><code class="literal">#(255 254 124 5)</code></span>
   and the byte <span class="data"><code class="literal">124</code></span> is <span class="strong"><strong>not</strong></span> a valid
   byte for a <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> file name because it
   means <span class="data"><code class="literal">|</code></span> in <a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a>.</p><p class="simpara">The set of valid pathname <span class="emphasis"><em>bytes</em></span> is
   determined by the <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/autoconf/" target="_top">autoconf</a> test
   <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/m4/filecharset.m4"><code class="filename">src/m4/filecharset.m4</code></a>
   at configure time. While rather stable for the first 127 bytes,
   on <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> it varies wildly for the bytes 128-256, depending on the
   OS version and the file system.</p><p class="simpara">The <a class="link" href="#newline" title="31.5.3. Line Terminators">line terminator</a> mode of <a href="impnotes.html#path-enc" class="olink"><code class="varname">CUSTOM:*PATHNAME-ENCODING*</code></a> is ignored.</p><p class="simpara"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.apple.com/macosx/" target="_top"><span class="platform">Mac OS X</span></a> platform only</span></span>:
   <a class="ulink" href="http://www.apple.com/macosx/" target="_top"><span class="platform">Mac OS X</span></a> pathnames are actually <a class="ulink" href="http://www.unicode.org/" target="_top"><span class="platform">UNICODE</span></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>s, so
   <a href="impnotes.html#path-enc" class="olink"><code class="varname">CUSTOM:*PATHNAME-ENCODING*</code></a> is a constant with value <a class="link" href="#charset-UTF-8"><code class="constant">CHARSET:UTF-8</code></a>.</p></dd><dt><span class="term"><strong class="first"><em class="firstterm"><a href="impnotes.html#term-enc" class="olink"><code class="varname">CUSTOM:*TERMINAL-ENCODING*</code></a>
   <a id="term-enc" class="indexterm"></a></em></strong></span></dt><dd>is the encoding used for communication with the
  terminal, in particular by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stterminal-iost.html" target="_top"><code class="varname">*TERMINAL-IO*</code></a>.
 </dd><dt><span class="term"><strong class="first"><em class="firstterm"><a href="impnotes.html#misc-enc" class="olink"><code class="varname">CUSTOM:*MISC-ENCODING*</code></a>
   <a id="misc-enc" class="indexterm"></a></em></strong></span></dt><dd>is the encoding used for access to <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html">environment variable</a>s,
 command line options, and the like.  Its <a class="link" href="#newline" title="31.5.3. Line Terminators">line terminator</a> mode is ignored.
 </dd><dt><span class="term"><strong class="first"><em class="firstterm"><a href="impnotes.html#foreign-enc" class="olink"><code class="varname">CUSTOM:*FOREIGN-ENCODING*</code></a>
   <a id="foreign-enc" class="indexterm"></a></em></strong></span></dt><dd>is the encoding for strings passed through the
 <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> (some platforms only). If it is a <a class="link" href="#enc1-1" title="“1:1” encodings"><span class="quote">“<span class="quote">1:1</span>”</span> encoding</a>,
 i.e. an encoding in which every character is represented by one byte,
 it is also used for passing characters through the <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>.
</dd></dl></div></dd></dl></div><p>The default encoding objects are initialized according to <code class="option"><a href="clisp.html#opt-enc" class="olink"><code class="option">-E<em class="replaceable"><code>domain</code></em> <em class="replaceable"><code>encoding</code></em></code></a></code>.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Reminder</h3><p>You have to use <a class="link" href="#letf" title="31.11.2. Macros EXT:LETF &amp; EXT:LETF*"><code class="function">EXT:LETF</code></a>/<a class="link" href="#letf" title="31.11.2. Macros EXT:LETF &amp; EXT:LETF*"><code class="function">EXT:LETF*</code></a>
  for <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-symbol-macro.html"><code class="classname">SYMBOL-MACRO</code></a>s; <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET</code></a>/<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET*</code></a> will <span class="strong"><strong>not</strong></span> work!</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="line-term-default"></a>31.5.6.1. Default <a class="link" href="#newline" title="31.5.3. Line Terminators">line terminator</a></h4></div></div></div><p>The <a class="link" href="#newline" title="31.5.3. Line Terminators">line terminator</a> facet of the above <a class="link" href="#encoding" title="31.5. Encodings"><code class="classname">EXT:ENCODING</code></a>s is determined by
 the following logic: since <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> understands all possible
 <a class="link" href="#newline" title="31.5.3. Line Terminators">line terminator</a>s on <span class="emphasis"><em>input</em></span> (see
 <a class="xref" href="#clhs-newline" title="13.11. Treatment of Newline during Input and Output sec_13-1-8">Section 13.11, “Treatment of Newline during Input and Output   sec_13-1-8”</a>), all that matters is what <a class="link" href="#newline" title="31.5.3. Line Terminators">line terminator</a>
 do most <span class="emphasis"><em>other</em></span> programs expect?</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> platform only.</span></span></span></dt><dd>If a non-0 <code class="literal">O_BINARY</code> <a class="ulink" href="http://gcc.gnu.org/onlinedocs/cpp/" target="_top"><span class="command"><strong>cpp</strong></span></a>
   constant is defined, we assume that the OS distinguishes between text
   and binary files, and, since the encodings are relevant only for text
   files, we thus use <code class="constant">:DOS</code>; otherwise the default is <code class="constant">:UNIX</code>.
</dd><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platform only.</span></span></span></dt><dd>Since most <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> programs expect CRLF, the default
  <a class="link" href="#newline" title="31.5.3. Line Terminators">line terminator</a> is <code class="constant">:DOS</code>.</dd></dl></div><p>This boils down to the following code
 in <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/encoding.d"><code class="filename">src/encoding.d</code></a>:
</p><pre class="programlisting">
 #if defined(WIN32) || (defined(UNIX) &amp;&amp; (O_BINARY != 0))
</pre><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="cygwin-line-term-default"></a>Default line terminator on   <span class="platform">Cygwin</span></h3><p><span class="emphasis"><em>Both</em></span> of the above tests
  pass on <a class="ulink" href="http://cygwin.com/" target="_top"><span class="platform">Cygwin</span></a>, so the default <a class="link" href="#newline" title="31.5.3. Line Terminators">line terminator</a> is <code class="constant">:DOS</code>.
  If you so desire, you can change it in your <a href="clisp.html#opt-norc" class="olink">RC file</a>.</p></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="string-byte"></a>31.5.7. Converting between strings and byte vectors</h3></div></div></div><p>Encodings can also be used to convert directly between strings and
their corresponding byte vector representation according to that encoding.
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">(<a class="link" href="#string-byte" title="31.5.7. Converting between strings and byte vectors"><code class="function">EXT:CONVERT-STRING-FROM-BYTES</code></a>
      <em class="replaceable"><code>vector</code></em> <em class="replaceable"><code>encoding</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:START</code> <code class="constant">:END</code>)</code></span></dt><dd>converts the subsequence of <em class="replaceable"><code>vector</code></em> (a <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8))</code></span>)
   from <em class="replaceable"><code>start</code></em> to <em class="replaceable"><code>end</code></em> to a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>, according to the given
   <em class="replaceable"><code>encoding</code></em>, and returns the resulting string.
</dd><dt><span class="term"><code class="code">(<a class="link" href="#string-byte" title="31.5.7. Converting between strings and byte vectors"><code class="function">EXT:CONVERT-STRING-TO-BYTES</code></a>
      <em class="replaceable"><code>string</code></em> <em class="replaceable"><code>encoding</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:START</code> <code class="constant">:END</code>)</code></span></dt><dd>converts the subsequence of <em class="replaceable"><code>string</code></em> from
   <em class="replaceable"><code>start</code></em> to <em class="replaceable"><code>end</code></em> to a <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8))</code></span>, according to the given
   <em class="replaceable"><code>encoding</code></em>, and returns the resulting byte vector.
</dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="gstream"></a>31.6. Generic streams</h2></div></div></div><p>This interface is <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>-specific and now obsolete.  Please use
 the <a class="link" href="#gray" title="Chapter 30. Gray streams">Gray streams</a> interface instead.</p><p>Generic streams are user programmable streams.
 The programmer interface:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">(<code class="function">gstream:make-generic-stream</code>
                 <em class="replaceable"><code>controller</code></em>)</code></span></dt><dd>returns a generic stream.
  </dd><dt><span class="term"><code class="code">(<code class="function">gstream:generic-stream-controller</code>
                 <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd>returns a private object to which generic stream
   methods dispatch.  The typical usage is to retrieve the object
   originally provided by the user in
   <code class="function">gstream:make-generic-stream</code>.
  </dd><dt><span class="term"><code class="code">(<code class="function">gstream:generic-stream-p</code>
                 <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd>determines whether a stream is a generic stream,
   returning <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> if it is, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> otherwise.
  </dd></dl></div><p>In order to specify the behavior of a generic stream, the user
 must define <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> methods on the following <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> generic
 functions.  The function <code class="function">gstream:generic-stream-<em class="replaceable"><code>x</code></em></code>
 corresponds to the <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> function <code class="function"><em class="replaceable"><code>x</code></em></code>.
 They all take a controller and some number of arguments.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">(gstream:generic-stream-read-char
                 <em class="replaceable"><code>controller</code></em>)</code></span></dt><dd> Returns and consumes the next character, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> at
    end of file.  Takes one argument, the controller object.
  </dd><dt><span class="term"><code class="code">(gstream:generic-stream-peek-char
                 <em class="replaceable"><code>controller</code></em>)</code></span></dt><dd> Returns the next character, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> at end of file.  A
   second value indicates whether the side effects associated with
   consuming the character were executed: <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> means that a full
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-char.html" target="_top"><code class="function">READ-CHAR</code></a> was done, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> means that no side effects were done.
   Takes one argument, the controller object.
  </dd><dt><span class="term"><code class="code">(gstream:generic-stream-read-byte
                 <em class="replaceable"><code>controller</code></em>)</code></span></dt><dd>Returns and consumes the next integer, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> at end
   of file.  Takes one argument, the controller object.
  </dd><dt><span class="term"><code class="code">(gstream:generic-stream-read-char-will-hang-p
     <em class="replaceable"><code>controller</code></em>)</code></span></dt><dd>This generic function is used to query the stream's
   input status.  It returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if
   <code class="function">gstream:generic-stream-read-char</code> and
   <code class="function">gstream:generic-stream-peek-char</code> will certainly
   return immediately.  Otherwise it returns true.
  </dd><dt><span class="term"><code class="code">(gstream:generic-stream-write-char
                 <em class="replaceable"><code>controller</code></em> <em class="replaceable"><code>char</code></em>)</code></span></dt><dd>The first argument is the controller object.
   The second argument is the character to be written.
  </dd><dt><span class="term"><code class="code">(gstream:generic-stream-write-byte
                 <em class="replaceable"><code>controller</code></em>
                 <em class="replaceable"><code>by</code></em>)</code></span></dt><dd>The first argument is the controller object.
   The second argument is the integer to be written.
  </dd><dt><span class="term"><code class="code">(gstream:generic-stream-write-string
                 <em class="replaceable"><code>controller</code></em>
                 <em class="replaceable"><code>string</code></em> <em class="replaceable"><code>start</code></em> <em class="replaceable"><code>length</code></em>)</code></span></dt><dd>Writes the subsequence of <em class="replaceable"><code>string</code></em> starting from
   <em class="replaceable"><code>start</code></em> of length <em class="replaceable"><code>length</code></em>.
   The first argument is the controller object.
  </dd><dt><span class="term"><code class="code">(gstream:generic-stream-clear-input
                 <em class="replaceable"><code>controller</code></em>)</code><br /></span><span class="term"><code class="code">(gstream:generic-stream-clear-output
     <em class="replaceable"><code>controller</code></em>)</code><br /></span><span class="term"><code class="code">(gstream:generic-stream-finish-output
     <em class="replaceable"><code>controller</code></em>)</code><br /></span><span class="term"><code class="code">(gstream:generic-stream-force-output
     <em class="replaceable"><code>controller</code></em>)</code><br /></span><span class="term"><code class="code">(gstream:generic-stream-close
     <em class="replaceable"><code>controller</code></em>)</code></span></dt><dd>Take one argument, the controller object.
 </dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="weak"></a>31.7. Weak Objects</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#weak-pointer">31.7.1. Weak Pointers</a></span></dt><dt><span class="section"><a href="#weak-list">31.7.2. Weak Lists</a></span></dt><dt><span class="section"><a href="#weak-and-relation">31.7.3. Weak <span class="quote">“<span class="quote">And</span>”</span> Relations</a></span></dt><dt><span class="section"><a href="#weak-or-relation">31.7.4. Weak <span class="quote">“<span class="quote">Or</span>”</span> Relations</a></span></dt><dt><span class="section"><a href="#weak-mapping">31.7.5. Weak Associations</a></span></dt><dt><span class="section"><a href="#weak-and-mapping">31.7.6. Weak <span class="quote">“<span class="quote">And</span>”</span> Mappings</a></span></dt><dt><span class="section"><a href="#weak-or-mapping">31.7.7. Weak <span class="quote">“<span class="quote">Or</span>”</span> Mappings</a></span></dt><dt><span class="section"><a href="#weak-alist">31.7.8. Weak Association Lists</a></span></dt><dt><span class="section"><a href="#weak-ht">31.7.9. Weak Hash Tables</a></span></dt></dl></div><p>Recall two terms: An object is called <span class="quote">“<span class="quote">"alive"</span>”</span> as
 long as it can be retrieved by the user or program, through any kind of
 references, starting from global and local variables. (Objects that
 consume no heap storage, also known as <span class="quote">“<span class="quote">"immediate
 objects"</span>”</span>, such as <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>s, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_fixnum.html" target="_top"><code class="classname">FIXNUM</code></a>s, and
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SHORT-FLOAT</code></a>s, are alive indefinitely.) An object is said to be
 <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed when its storage is reclaimed, at some moment after it becomes
 <span class="quote">“<span class="quote">"dead"</span>”</span>.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="weak-pointer"></a>31.7.1. Weak Pointers</h3></div></div></div><p>A <a class="link" href="#weak-pointer" title="31.7.1. Weak Pointers"><code class="classname">EXT:WEAK-POINTER</code></a> is an object holding a reference to a given object,
 without keeping the latter from being <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed.</p><div class="variablelist"><p class="title"><strong>Weak Pointer API</strong></p><dl class="variablelist"><dt><span class="term"><code class="code">(<code class="function">EXT:MAKE-WEAK-POINTER</code>
   <em class="replaceable"><code>value</code></em>)</code></span></dt><dd>returns a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_f.html#fresh">fresh</a> <a class="link" href="#weak-pointer" title="31.7.1. Weak Pointers"><code class="classname">EXT:WEAK-POINTER</code></a> referring to
   <em class="replaceable"><code>value</code></em>.</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-POINTER-P</code> <em class="replaceable"><code>object</code></em>)</code></span></dt><dd>returns true if the <em class="replaceable"><code>object</code></em> is of type
   <a class="link" href="#weak-pointer" title="31.7.1. Weak Pointers"><code class="classname">EXT:WEAK-POINTER</code></a>.</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-POINTER-VALUE</code>
   <em class="replaceable"><code>weak-pointer</code></em>)</code></span></dt><dd>returns two values: The original value and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>,
   if the value has not yet been <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed, else <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
   It is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>-able: you can change the value that the weak pointer
   points to.</dd></dl></div><p>Weak pointers are useful for notification-based communication
 protocols between software modules, e.g. when a change to an object
 <em class="replaceable"><code>x</code></em> requires a notification to an object <em class="replaceable"><code>y</code></em>, as long as <em class="replaceable"><code>y</code></em> is
 alive.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="weak-list"></a>31.7.2. Weak Lists</h3></div></div></div><p>A <a class="link" href="#weak-list" title="31.7.2. Weak Lists"><code class="classname">EXT:WEAK-LIST</code></a> is an ordered collection of references to objects
 that does <span class="strong"><strong>not</strong></span> keep the objects from being <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed. It is
 semantically equivalent to a list of <a class="link" href="#weak-pointer" title="31.7.1. Weak Pointers"><code class="classname">EXT:WEAK-POINTER</code></a>s, however with a
 more efficient in-memory representation than a plain list of
 <a class="link" href="#weak-pointer" title="31.7.1. Weak Pointers"><code class="classname">EXT:WEAK-POINTER</code></a>s would be.</p><div class="variablelist"><p class="title"><strong>Weak List API</strong></p><dl class="variablelist"><dt><span class="term"><code class="code">(<code class="function">EXT:MAKE-WEAK-LIST</code> <em class="replaceable"><code>list</code></em>)</code></span></dt><dd>creates a <a class="link" href="#weak-list" title="31.7.2. Weak Lists"><code class="classname">EXT:WEAK-LIST</code></a> pointing to each of the
   elements in the given <em class="replaceable"><code>list</code></em>.</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-LIST-P</code> <em class="replaceable"><code>object</code></em>)</code></span></dt><dd>returns true if the <em class="replaceable"><code>object</code></em> is of type
   <a class="link" href="#weak-list" title="31.7.2. Weak Lists"><code class="classname">EXT:WEAK-LIST</code></a>.</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-LIST-LIST</code>
   <em class="replaceable"><code>weak-list</code></em>)</code></span></dt><dd>returns a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of those objects from the
   <em class="replaceable"><code>weak-list</code></em> that are still
   alive.</dd><dt><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<code class="function">EXT:WEAK-LIST-LIST</code>
   <em class="replaceable"><code>weak-list</code></em>) <em class="replaceable"><code>list</code></em>)</code></span></dt><dd>replaces the list of objects stored by the
   <em class="replaceable"><code>weak-list</code></em>.</dd></dl></div><p>Weak lists are useful for notification based communication
 protocols between software modules, e.g. when a change to an object
 <em class="replaceable"><code>x</code></em> requires a notification to objects <em class="replaceable"><code>k<sub>1</sub></code></em>, <em class="replaceable"><code>k<sub>2</sub></code></em>, ..., as long
 as such a particular <em class="replaceable"><code>k<sub>n</sub></code></em> is alive.</p><p>A <a class="link" href="#weak-list" title="31.7.2. Weak Lists"><code class="classname">EXT:WEAK-LIST</code></a> with a single element is semantically equivalent to a
 single <a class="link" href="#weak-pointer" title="31.7.1. Weak Pointers"><code class="classname">EXT:WEAK-POINTER</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="weak-and-relation"></a>31.7.3. Weak <span class="quote">“<span class="quote">And</span>”</span> Relations</h3></div></div></div><p>A weak <span class="quote">“<span class="quote">and</span>”</span> relation is an ordered collection of
 references to objects, that does <span class="strong"><strong>not</strong></span> keep the objects from being
 <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed, and which allows access to all the objects as long as all of
 them are still alive. As soon as one of them is <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed, the entire
 collection of objects becomes empty.</p><div class="variablelist"><p class="title"><strong>Weak <span class="quote">“<span class="quote">And</span>”</span> Relation API</strong></p><dl class="variablelist"><dt><span class="term"><code class="code">(<code class="function">EXT:MAKE-WEAK-AND-RELATION</code>
   <em class="replaceable"><code>list</code></em>)</code></span></dt><dd>creates a <a class="link" href="#weak-and-relation" title="31.7.3. Weak “And” Relations"><code class="classname">EXT:WEAK-AND-RELATION</code></a> between the objects in
   the given <em class="replaceable"><code>list</code></em>.</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-AND-RELATION-P</code>
   <em class="replaceable"><code>object</code></em>)</code></span></dt><dd>returns true if the <em class="replaceable"><code>object</code></em> is of type
   <a class="link" href="#weak-and-relation" title="31.7.3. Weak “And” Relations"><code class="classname">EXT:WEAK-AND-RELATION</code></a>.</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-AND-RELATION-LIST</code>
   <em class="replaceable"><code>weak-and-relation</code></em>)</code></span></dt><dd>returns the list of objects stored in the
   <em class="replaceable"><code>weak-and-relation</code></em>. The returned list must not
   be destructively modified.</dd></dl></div><p><a class="link" href="#weak-and-relation" title="31.7.3. Weak “And” Relations"><code class="classname">EXT:WEAK-AND-RELATION</code></a>s are useful to model relations between objects
 that become worthless when one of the objects dies.</p><p>A <a class="link" href="#weak-and-relation" title="31.7.3. Weak “And” Relations"><code class="classname">EXT:WEAK-AND-RELATION</code></a> with a single element is semantically
 equivalent to a <a class="link" href="#weak-pointer" title="31.7.1. Weak Pointers"><code class="classname">EXT:WEAK-POINTER</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="weak-or-relation"></a>31.7.4. Weak <span class="quote">“<span class="quote">Or</span>”</span> Relations</h3></div></div></div><p>A weak <span class="quote">“<span class="quote">or</span>”</span> relation is an ordered collection of
 references to objects, that keeps all objects from being <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed as long
 as one of them is still alive. In other words, each of them keeps all
 others among them from being <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed. When all of them are unreferenced,
 the collection of objects becomes empty.</p><div class="variablelist"><p class="title"><strong>Weak <span class="quote">“<span class="quote">Or</span>”</span> Relation API</strong></p><dl class="variablelist"><dt><span class="term"><code class="code">(<code class="function">EXT:MAKE-WEAK-OR-RELATION</code>
   <em class="replaceable"><code>list</code></em>)</code></span></dt><dd>creates a <a class="link" href="#weak-or-relation" title="31.7.4. Weak “Or” Relations"><code class="classname">EXT:WEAK-OR-RELATION</code></a> between the objects in
   the given <em class="replaceable"><code>list</code></em>.</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-OR-RELATION-P</code>
   <em class="replaceable"><code>object</code></em>)</code></span></dt><dd>returns true if the <em class="replaceable"><code>object</code></em> is of type
   <a class="link" href="#weak-or-relation" title="31.7.4. Weak “Or” Relations"><code class="classname">EXT:WEAK-OR-RELATION</code></a>.</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-OR-RELATION-LIST</code>
   <em class="replaceable"><code>weak-or-relation</code></em>)</code></span></dt><dd>returns the list of objects stored in the
   <em class="replaceable"><code>weak-or-relation</code></em>. The returned list must not
   be destructively modified.</dd></dl></div><p><a class="link" href="#weak-or-relation" title="31.7.4. Weak “Or” Relations"><code class="classname">EXT:WEAK-OR-RELATION</code></a>s are useful to model relations between objects
 that do not become worthless when one of the objects dies.</p><p>A <a class="link" href="#weak-or-relation" title="31.7.4. Weak “Or” Relations"><code class="classname">EXT:WEAK-OR-RELATION</code></a> with a single element is semantically
 equivalent to a <a class="link" href="#weak-pointer" title="31.7.1. Weak Pointers"><code class="classname">EXT:WEAK-POINTER</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="weak-mapping"></a>31.7.5. Weak Associations</h3></div></div></div><p>A weak association is a mapping from an object called <em class="replaceable"><code>key</code></em> to
 an object called <em class="replaceable"><code>value</code></em>, that exists as long as the key is alive. In
 other words, as long as the key is alive, it keeps the value from being
 <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed.</p><div class="variablelist"><p class="title"><strong>Weak Association API</strong></p><dl class="variablelist"><dt><span class="term"><code class="code">(<code class="function">EXT:MAKE-WEAK-MAPPING</code>
   <em class="replaceable"><code>key</code></em> <em class="replaceable"><code>value</code></em>)</code></span></dt><dd>creates a <a class="link" href="#weak-mapping" title="31.7.5. Weak Associations"><code class="classname">EXT:WEAK-MAPPING</code></a>.
</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-MAPPING-P</code>
   <em class="replaceable"><code>object</code></em>)</code></span></dt><dd>returns true if the object is of type
   <a class="link" href="#weak-mapping" title="31.7.5. Weak Associations"><code class="classname">EXT:WEAK-MAPPING</code></a>.</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-MAPPING-PAIR</code>
   <em class="replaceable"><code>weak-mapping</code></em>)</code></span></dt><dd>returns three values: the original key, the original
   value, and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>, if the key has not yet been <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed, else <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-MAPPING-VALUE</code>
   <em class="replaceable"><code>weak-mapping</code></em>)</code></span></dt><dd>returns the value, if the key has not yet been <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed,
   else <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</dd><dt><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<code class="function">EXT:WEAK-MAPPING-VALUE</code>
   <em class="replaceable"><code>weak-mapping</code></em>) <em class="replaceable"><code>value</code></em>)</code></span></dt><dd>replaces the value stored in the
   <em class="replaceable"><code>weak-mapping</code></em>. It has no effect when the
   key has already been <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed.</dd></dl></div><p>Weak associations are useful to supplement objects with additional
 information that is stored outside of the object.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="weak-and-mapping"></a>31.7.6. Weak <span class="quote">“<span class="quote">And</span>”</span> Mappings</h3></div></div></div><p>A weak <span class="quote">“<span class="quote">and</span>”</span> mapping is a mapping from a tuple of
 objects called <em class="replaceable"><code>keys</code></em> to an object called <em class="replaceable"><code>value</code></em>, that does
 <span class="strong"><strong>not</strong></span> keep the keys from being <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed and that exists as long as all
 keys are alive. As soon as one of the keys is <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed, the entire
 mapping goes away.</p><div class="variablelist"><p class="title"><strong>Weak <span class="quote">“<span class="quote">And</span>”</span> Mapping API</strong></p><dl class="variablelist"><dt><span class="term"><code class="code">(<code class="function">EXT:MAKE-WEAK-AND-MAPPING</code>
   <em class="replaceable"><code>keys</code></em> <em class="replaceable"><code>value</code></em>)</code></span></dt><dd>creates a <a class="link" href="#weak-and-mapping" title="31.7.6. Weak “And” Mappings"><code class="classname">EXT:WEAK-AND-MAPPING</code></a> between the <em class="replaceable"><code>keys</code></em>
   objects in the given list and the given <em class="replaceable"><code>value</code></em>.
   The <em class="replaceable"><code>keys</code></em> list must be non-empty.</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-AND-MAPPING-P</code>
   <em class="replaceable"><code>object</code></em>)</code></span></dt><dd>returns true if the <em class="replaceable"><code>object</code></em> is of type
   <a class="link" href="#weak-and-mapping" title="31.7.6. Weak “And” Mappings"><code class="classname">EXT:WEAK-AND-MAPPING</code></a>.</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-AND-MAPPING-PAIR</code>
   <em class="replaceable"><code>weak-and-mapping</code></em>)</code></span></dt><dd>returns three values: the list of keys, the value,
   and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>, if none of the keys have been <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed, else <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
   The returned keys list must not be destructively modified.
</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-AND-MAPPING-VALUE</code>
   <em class="replaceable"><code>weak-and-mapping</code></em>)</code></span></dt><dd>returns the value, if none of the keys have been
   <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed, else <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</dd><dt><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>
   (<code class="function">EXT:WEAK-AND-MAPPING-VALUE</code>
   <em class="replaceable"><code>weak-and-mapping</code></em>) <em class="replaceable"><code>value</code></em>)</code></span></dt><dd>replaces the value stored in the
   <em class="replaceable"><code>weak-and-mapping</code></em>. It has no effect when
   some key has already been <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed.</dd></dl></div><p><a class="link" href="#weak-and-mapping" title="31.7.6. Weak “And” Mappings"><code class="classname">EXT:WEAK-AND-MAPPING</code></a>s are useful to model properties of sets of
 objects that become worthless when one of the objects dies.</p><p>A <a class="link" href="#weak-and-mapping" title="31.7.6. Weak “And” Mappings"><code class="classname">EXT:WEAK-AND-MAPPING</code></a> with a single key is semantically equivalent
 to a weak association.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="weak-or-mapping"></a>31.7.7. Weak <span class="quote">“<span class="quote">Or</span>”</span> Mappings</h3></div></div></div><p>A weak <span class="quote">“<span class="quote">or</span>”</span> mapping is a mapping from a tuple of
 objects called <em class="replaceable"><code>keys</code></em> to an object called <em class="replaceable"><code>value</code></em>, that keeps all
 keys and the value from being <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed as long as one of the keys is
 still alive. In other words, each of the keys keeps all others among
 them and the value from being <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed.  When all of them are
 unreferenced, the entire mapping goes away.</p><div class="variablelist"><p class="title"><strong>Weak <span class="quote">“<span class="quote">Or</span>”</span> Mapping API</strong></p><dl class="variablelist"><dt><span class="term"><code class="code">(<code class="function">EXT:MAKE-WEAK-OR-MAPPING</code>
   <em class="replaceable"><code>keys</code></em> <em class="replaceable"><code>value</code></em>)</code></span></dt><dd> creates a <a class="link" href="#weak-or-mapping" title="31.7.7. Weak “Or” Mappings"><code class="classname">EXT:WEAK-OR-MAPPING</code></a> between the
   <em class="replaceable"><code>keys</code></em> objects in the given list and the given
   <em class="replaceable"><code>value</code></em>. The <em class="replaceable"><code>keys</code></em> list must be
   non-empty.</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-OR-MAPPING-P</code>
   <em class="replaceable"><code>object</code></em>)</code></span></dt><dd>returns true if the <em class="replaceable"><code>object</code></em> is of type
   <a class="link" href="#weak-or-mapping" title="31.7.7. Weak “Or” Mappings"><code class="classname">EXT:WEAK-OR-MAPPING</code></a>.</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-OR-MAPPING-PAIR</code>
   <em class="replaceable"><code>weak-or-mapping</code></em>)</code></span></dt><dd>returns three values: the list of keys, the value,
   and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>, if the keys have not yet been <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed, else <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
   The returned keys list must not be destructively modified.
</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-OR-MAPPING-VALUE</code>
   <em class="replaceable"><code>weak-or-mapping</code></em>)</code></span></dt><dd>returns the value, if the keys have not yet been <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed,
   else <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</dd><dt><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<code class="function">EXT:WEAK-OR-MAPPING-VALUE</code>
   <em class="replaceable"><code>weak-or-mapping</code></em>) <em class="replaceable"><code>value</code></em>)</code></span></dt><dd>replaces the value stored in the
   <em class="replaceable"><code>weak-or-mapping</code></em>. It has no effect when the
   keys have already been <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed.</dd></dl></div><p><a class="link" href="#weak-or-mapping" title="31.7.7. Weak “Or” Mappings"><code class="classname">EXT:WEAK-OR-MAPPING</code></a>s are useful to model properties of sets of
 objects that do not become worthless when one of the objects dies.</p><p>A <a class="link" href="#weak-or-mapping" title="31.7.7. Weak “Or” Mappings"><code class="classname">EXT:WEAK-OR-MAPPING</code></a> with a single key is semantically equivalent
 to a weak association.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="weak-alist"></a>31.7.8. Weak Association Lists</h3></div></div></div><p>A weak association list is an ordered collection of pairs, each
 pair being built from an object called <em class="replaceable"><code>key</code></em> and an object called
 <em class="replaceable"><code>value</code></em>.  The lifetime of each pair depends on the type of the weak
 <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_a.html#association_list">association list</a>:
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:KEY</code></span></dt><dd>The pair exists as long as the <em class="replaceable"><code>key</code></em> is not <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed.
    As long as the <em class="replaceable"><code>key</code></em> is alive, it prevents the <em class="replaceable"><code>value</code></em> from
    being <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed.</dd><dt><span class="term"><code class="constant">:VALUE</code></span></dt><dd>The pair exists as long as the <em class="replaceable"><code>value</code></em> is not <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed.
   As long as the <em class="replaceable"><code>value</code></em> is alive, it prevents the <em class="replaceable"><code>key</code></em> from
   being <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed.</dd><dt><span class="term"><code class="constant">:KEY-AND-VALUE</code></span></dt><dd>The pair exists as long as the <em class="replaceable"><code>key</code></em> and the <em class="replaceable"><code>value</code></em>
   are alive.
 </dd><dt><span class="term"><code class="constant">:KEY-OR-VALUE</code></span></dt><dd>The pair exists as long as the <em class="replaceable"><code>key</code></em> or the <em class="replaceable"><code>value</code></em>
   are alive.  As long as the <em class="replaceable"><code>key</code></em> is alive, it prevents the <em class="replaceable"><code>value</code></em>
   from being <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed, and as long as the <em class="replaceable"><code>value</code></em> is alive, it prevents the
   <em class="replaceable"><code>key</code></em> from being <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed.</dd></dl></div><p>
In other words, each pair is:
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:KEY</code></span></dt><dd>a <a class="link" href="#weak-mapping" title="31.7.5. Weak Associations"><code class="classname">EXT:WEAK-MAPPING</code></a> from the <em class="replaceable"><code>key</code></em> to the <em class="replaceable"><code>value</code></em>,
 </dd><dt><span class="term"><code class="constant">:VALUE</code></span></dt><dd>a <a class="link" href="#weak-mapping" title="31.7.5. Weak Associations"><code class="classname">EXT:WEAK-MAPPING</code></a> from the <em class="replaceable"><code>value</code></em> to the <em class="replaceable"><code>key</code></em>,
 </dd><dt><span class="term"><code class="constant">:KEY-AND-VALUE</code></span></dt><dd>a <a class="link" href="#weak-and-relation" title="31.7.3. Weak “And” Relations"><code class="classname">EXT:WEAK-AND-RELATION</code></a> of the <em class="replaceable"><code>key</code></em> and the <em class="replaceable"><code>value</code></em>,
 </dd><dt><span class="term"><code class="constant">:KEY-OR-VALUE</code></span></dt><dd>a <a class="link" href="#weak-or-relation" title="31.7.4. Weak “Or” Relations"><code class="classname">EXT:WEAK-OR-RELATION</code></a> of the <em class="replaceable"><code>key</code></em> and the <em class="replaceable"><code>value</code></em>.
 </dd></dl></div><div class="variablelist"><p class="title"><strong>Weak Association List API</strong></p><dl class="variablelist"><dt><span class="term"><code class="code">(<code class="function">EXT:MAKE-WEAK-ALIST</code>
   :type :initial-contents)</code></span></dt><dd>creates a <a class="link" href="#weak-alist" title="31.7.8. Weak Association Lists"><code class="classname">EXT:WEAK-ALIST</code></a>. The <em class="replaceable"><code>type</code></em> argument
   must be one of the four aforementioned types; the default is <code class="constant">:KEY</code>.
   The <em class="replaceable"><code>initial-contents</code></em> argument must be an
   <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_a.html#association_list">association list</a>.</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-ALIST-P</code> <em class="replaceable"><code>object</code></em>)</code></span></dt><dd>returns true if the <em class="replaceable"><code>object</code></em> is of type
   <a class="link" href="#weak-alist" title="31.7.8. Weak Association Lists"><code class="classname">EXT:WEAK-ALIST</code></a>.</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-ALIST-TYPE</code>
   <em class="replaceable"><code>weak-alist</code></em>)</code></span></dt><dd>returns the type of the
   <em class="replaceable"><code>weak-alist</code></em>.</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-ALIST-CONTENTS</code>
   <em class="replaceable"><code>weak-alist</code></em>)</code></span></dt><dd>returns an <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_a.html#association_list">association list</a> that corresponds to the current
   contents of the <em class="replaceable"><code>weak-alist</code></em>.
</dd><dt><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<code class="function">EXT:WEAK-ALIST-CONTENTS</code>
   <em class="replaceable"><code>weak-alist</code></em>)
   <em class="replaceable"><code>contents</code></em>)</code></span></dt><dd>replaces the contents of a
   <em class="replaceable"><code>weak-alist</code></em>. The
   <em class="replaceable"><code>contents</code></em> argument must be an
   <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_a.html#association_list">association list</a>.</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-ALIST-ASSOC</code> <em class="replaceable"><code>item</code></em>
   <em class="replaceable"><code>weak-alist</code></em>
   [:test] [:test-not] [:key])</code></span></dt><dd>is equivalent to
   <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_assoccm_a_assoc-if-not.html" target="_top"><code class="function">ASSOC</code></a> <em class="replaceable"><code>item</code></em> (<code class="function">EXT:WEAK-ALIST-CONTENTS</code>
    <em class="replaceable"><code>weak-alist</code></em>)
    [:test] [:test-not] [:key])</code>.
</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-ALIST-RASSOC</code> <em class="replaceable"><code>item</code></em>
   <em class="replaceable"><code>weak-alist</code></em>
   [:test] [:test-not] [:key])</code></span></dt><dd>is equivalent to
   <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_rassoccm__assoc-if-not.html" target="_top"><code class="function">RASSOC</code></a> <em class="replaceable"><code>item</code></em> (<code class="function">EXT:WEAK-ALIST-CONTENTS</code>
    <em class="replaceable"><code>weak-alist</code></em>)
    [:test] [:test-not] [:key])</code>.
</dd><dt><span class="term"><code class="code">(<code class="function">EXT:WEAK-ALIST-VALUE</code> <em class="replaceable"><code>item</code></em>
   <em class="replaceable"><code>weak-alist</code></em> [:test] [:test-not])</code></span></dt><dd>is equivalent to
   <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDR</code></a> (<code class="function">EXT:WEAK-LIST-ASSOC</code>
    <em class="replaceable"><code>item</code></em> <em class="replaceable"><code>weak-alist</code></em>
    [:test] [:test-not]))</code>.
</dd><dt><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<code class="function">EXT:WEAK-ALIST-VALUE</code>
   <em class="replaceable"><code>item</code></em> <em class="replaceable"><code>weak-alist</code></em> [:test] [:test-not])
   <em class="replaceable"><code>value</code></em>)</code></span></dt><dd>replaces the value stored for <em class="replaceable"><code>item</code></em> in
   a <em class="replaceable"><code>weak-alist</code></em>.  When a pair with the given
   <em class="replaceable"><code>item</code></em> as key does not exist or has already been <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed, a new pair
   is added to the <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_a.html#association_list">association list</a>.</dd></dl></div><p>Weak associations lists are useful to supplement objects with
 additional information that is stored outside of the object, when the
 number of such objects is known to be small.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="weak-ht"></a>31.7.9. Weak Hash Tables</h3></div></div></div><p>A weak <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a> is an unordered collection of pairs, each
 pair being built from an object called <em class="replaceable"><code>key</code></em> and an object called
 <em class="replaceable"><code>value</code></em>. There can be only one pair with a given <em class="replaceable"><code>key</code></em> in a weak
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a>. The lifetime of each pair depends on the type of the
 weak <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a>
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:KEY</code></span></dt><dd>The pair exists as long as the <em class="replaceable"><code>key</code></em> is not <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed.
    As long as the <em class="replaceable"><code>key</code></em> is alive, it prevents the <em class="replaceable"><code>value</code></em> from
    being <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed.</dd><dt><span class="term"><code class="constant">:VALUE</code></span></dt><dd>The pair exists as long as the <em class="replaceable"><code>value</code></em> is not <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed.
     As long as the <em class="replaceable"><code>value</code></em> is alive, it prevents the <em class="replaceable"><code>key</code></em> from
     being <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed.</dd><dt><span class="term"><code class="constant">:KEY-AND-VALUE</code></span></dt><dd>The pair exists as long as the <em class="replaceable"><code>key</code></em> and the
     <em class="replaceable"><code>value</code></em> are alive.</dd><dt><span class="term"><code class="constant">:KEY-OR-VALUE</code></span></dt><dd>The pair exists as long as the <em class="replaceable"><code>key</code></em> or the
     <em class="replaceable"><code>value</code></em> are alive.  As long as the <em class="replaceable"><code>key</code></em> is alive, it prevents
     the <em class="replaceable"><code>key</code></em> from being <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed, and as long as the <em class="replaceable"><code>value</code></em> is
     alive, it prevents the <em class="replaceable"><code>key</code></em> from being <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed.
  </dd></dl></div><p>
In other words, each pair is:
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:KEY</code></span></dt><dd>a <a class="link" href="#weak-mapping" title="31.7.5. Weak Associations"><code class="classname">EXT:WEAK-MAPPING</code></a> from the <em class="replaceable"><code>key</code></em> to the <em class="replaceable"><code>value</code></em>,
 </dd><dt><span class="term"><code class="constant">:VALUE</code></span></dt><dd>a <a class="link" href="#weak-mapping" title="31.7.5. Weak Associations"><code class="classname">EXT:WEAK-MAPPING</code></a> from the <em class="replaceable"><code>value</code></em> to the <em class="replaceable"><code>key</code></em>,
 </dd><dt><span class="term"><code class="constant">:KEY-AND-VALUE</code></span></dt><dd>a <a class="link" href="#weak-and-relation" title="31.7.3. Weak “And” Relations"><code class="classname">EXT:WEAK-AND-RELATION</code></a> of the <em class="replaceable"><code>key</code></em> and the <em class="replaceable"><code>value</code></em>,
 </dd><dt><span class="term"><code class="constant">:KEY-OR-VALUE</code></span></dt><dd>a <a class="link" href="#weak-or-relation" title="31.7.4. Weak “Or” Relations"><code class="classname">EXT:WEAK-OR-RELATION</code></a> of the <em class="replaceable"><code>key</code></em> and the <em class="replaceable"><code>value</code></em>.
</dd></dl></div><p>See also <a class="xref" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE">Section 18.2, “Function <code class="function">MAKE-HASH-TABLE</code>”</a>.</p><p>Weak <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a>s are useful to supplement objects with
 additional information that is stored outside of the object. This data
 structure scales up without performance degradation when the number of
 pairs is big.</p><p>Weak <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a>s are also useful to implement canonicalization
 tables.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="final"></a>31.8. Finalization</h2></div></div></div><p>Calling <code class="code">(<a class="link" href="#final" title="31.8. Finalization"><code class="function">EXT:FINALIZE</code></a> <em class="replaceable"><code>object</code></em> <em class="replaceable"><code>function</code></em>)</code>
 has the effect that when the specified object is being <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed,
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_funcall.html" target="_top"><code class="function">FUNCALL</code></a> <em class="replaceable"><code>function</code></em> <em class="replaceable"><code>object</code></em>)</code> will be executed.</p><p>Calling <code class="code">(<a class="link" href="#final" title="31.8. Finalization"><code class="function">EXT:FINALIZE</code></a> <em class="replaceable"><code>object</code></em> <em class="replaceable"><code>function</code></em> <em class="replaceable"><code>guardian</code></em>)</code>
 has a similar effect, but only as long as the <em class="replaceable"><code>guardian</code></em> has not been <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed:
 when <em class="replaceable"><code>object</code></em> is being <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed, <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_funcall.html" target="_top"><code class="function">FUNCALL</code></a> <em class="replaceable"><code>function</code></em> <em class="replaceable"><code>object</code></em>
 <em class="replaceable"><code>guardian</code></em>)</code> will be executed.
 If the <em class="replaceable"><code>guardian</code></em> is <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed before <em class="replaceable"><code>object</code></em> is, nothing happens.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>The time when <span class="quote">“<span class="quote">the <em class="replaceable"><code>object</code></em> is being <a href="impnotes.html#gc" class="olink">garbage-collect</a>ed</span>”</span> is not
  defined deterministically.  (Actually, it might possibly never occur.)
  It denotes a moment at which no references to <em class="replaceable"><code>object</code></em> exist from other
  Lisp objects.  When the <em class="replaceable"><code>function</code></em> is called, <em class="replaceable"><code>object</code></em> (and, possibly,
  <em class="replaceable"><code>guardian</code></em>) enter the <span class="quote">“<span class="quote">arena of live Lisp objects</span>”</span> again.
</p></div><p>No finalization request will be executed more than once.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="prompt"></a>31.9. The Prompt</h2></div></div></div><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> prompt consists of 3 mandatory parts: <span class="quote">“<span class="quote">start</span>”</span>,
 <span class="quote">“<span class="quote">body</span>”</span>, and <span class="quote">“<span class="quote">finish</span>”</span>; and 2 optional parts:
 <span class="quote">“<span class="quote">break</span>”</span>, which appears only in the <a class="link" href="#debugger" title="25.2. Debugging Utilities sec_25-1-2">debugger</a> (after <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_break.html" target="_top"><code class="function">BREAK</code></a>
 or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_error.html" target="_top"><code class="function">ERROR</code></a>), and <span class="quote">“<span class="quote">step</span>”</span>, which appears only in the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_step.html" target="_top"><code class="function">STEP</code></a>er.
 Each part is controlled by a custom variable, which can be either a
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> or a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a> of no arguments returning a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>
 (if it is something else - or if the return value was not a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>
 - it is printed with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">PRINC</code></a>).  In the order of invocation:</p><div class="variablelist"><dl class="variablelist"><dt><a id="prompt-start"></a><span class="term"><a class="link" href="#prompt-start"><code class="varname">CUSTOM:*PROMPT-START*</code></a></span></dt><dd>Defaults to an empty string.
  </dd><dt><a id="prompt-step"></a><span class="term"><a class="link" href="#prompt-step"><code class="varname">CUSTOM:*PROMPT-STEP*</code></a></span></dt><dd>Used only during <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_step.html" target="_top"><code class="function">STEP</code></a>ping.
     Defaults to <span class="quote">“<span class="quote"><code class="prompt">Step n </code></span>”</span>,
     where <em class="replaceable"><code>n</code></em> is the stepping level as returned by <a class="link" href="#step-level"><code class="function">EXT:STEP-LEVEL</code></a>.
  </dd><dt><a id="prompt-break"></a><span class="term"><a class="link" href="#prompt-break"><code class="varname">CUSTOM:*PROMPT-BREAK*</code></a></span></dt><dd>Used only inside break loop (during debugging).
     Defaults to <span class="quote">“<span class="quote"><code class="prompt">Break n </code></span>”</span>,
     where <em class="replaceable"><code>n</code></em> is the break level as returned by <a class="link" href="#break-level"><code class="function">EXT:BREAK-LEVEL</code></a>.
  </dd><dt><a id="prompt-body"></a><span class="term"><a class="link" href="#prompt-body"><code class="varname">CUSTOM:*PROMPT-BODY*</code></a></span></dt><dd>Defaults to <span class="quote">“<span class="quote"><code class="prompt">package[n]</code></span>”</span>
     where <em class="replaceable"><code>package</code></em> is the shortest (nick)name (as returned by
     <a class="link" href="#package-shortest-name"><code class="function">EXT:PACKAGE-SHORTEST-NAME</code></a>) of the current package <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stpackagest.html" target="_top"><code class="varname">*PACKAGE*</code></a>
     if it is <span class="strong"><strong>not</strong></span> the same as it was in the beginning
     (determined by <a class="link" href="#prompt-new-package"><code class="function">EXT:PROMPT-NEW-PACKAGE</code></a>)
     or if it does not contain symbol <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>,
     (it is assumed that in the latter case you would want to keep in
     mind that your current package is something weird);
     and <em class="replaceable"><code>n</code></em> is the index of the current prompt, kept in <a class="link" href="#command-index"><code class="varname">EXT:*COMMAND-INDEX*</code></a>.
  </dd><dt><a id="prompt-finish"></a><span class="term"><a class="link" href="#prompt-finish"><code class="varname">CUSTOM:*PROMPT-FINISH*</code></a></span></dt><dd>Defaults to <span class="quote">“<span class="quote"><code class="prompt">&gt; </code></span>”</span>.
</dd></dl></div><p>To facilitate your own custom prompt creation, the following
 functions and variables are available:</p><div class="variablelist"><dl class="variablelist"><dt><a id="break-level"></a><span class="term"><a class="link" href="#break-level"><code class="function">EXT:BREAK-LEVEL</code></a></span></dt><dd>This <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a> returns current <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_break.html" target="_top"><code class="function">BREAK</code></a>/<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_error.html" target="_top"><code class="function">ERROR</code></a> level.
  </dd><dt><a id="step-level"></a><span class="term"><a class="link" href="#step-level"><code class="function">EXT:STEP-LEVEL</code></a></span></dt><dd>This <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a> returns current <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_step.html" target="_top"><code class="function">STEP</code></a> level.
  </dd><dt><a id="prompt-new-package"></a><span class="term"><a class="link" href="#prompt-new-package"><code class="function">EXT:PROMPT-NEW-PACKAGE</code></a></span></dt><dd>This <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a> returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stpackagest.html" target="_top"><code class="varname">*PACKAGE*</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
     if the current package is the same as it was initially.
  </dd><dt><a id="package-shortest-name"></a><span class="term"><a class="link" href="#package-shortest-name"><code class="function">EXT:PACKAGE-SHORTEST-NAME</code></a></span></dt><dd>This <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a> takes one argument, a
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_package.html" target="_top"><code class="classname">PACKAGE</code></a>, and returns its shortest name or nickname.
  </dd><dt><a id="command-index"></a><span class="term"><a class="link" href="#command-index"><code class="varname">EXT:*COMMAND-INDEX*</code></a></span></dt><dd>contains the current prompt number;
     it is your responsibility to increment it
     (this variable is bound to 0 before saving the <a href="impnotes.html#image" class="olink">memory image</a>).
  </dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ansi"></a>31.10. Maximum ANSI CL compliance</h2></div></div></div><p>Some [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] features are turned off by default for convenience and
 backward compatibility.
 They can be switched on, all at once, by setting the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-symbol-macro.html"><code class="classname">SYMBOL-MACRO</code></a>
 <a href="impnotes.html#ansi" class="olink"><code class="varname">CUSTOM:*ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>, or they can be switched on individually.
 Setting <a href="impnotes.html#ansi" class="olink"><code class="varname">CUSTOM:*ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> implies the following:</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">Setting <a class="link" href="#pathprint" title="22.6.1. Printing Pathnames sec_22-1-3-11"><code class="varname">CUSTOM:*PRINT-PATHNAMES-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.</li><li class="listitem">Setting <a class="link" href="#spacecharprint" title="22.3. Printing Characters sec_22-1-3-2"><code class="varname">CUSTOM:*PRINT-SPACE-CHAR-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.</li><li class="listitem">Setting <a class="link" href="#fixnum-char-ansi" title="Function COERCE"><code class="varname">CUSTOM:*COERCE-FIXNUM-CHAR-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.</li><li class="listitem">Setting <a class="link" href="#count-ansi" title="Variable CUSTOM:*SEQUENCE-COUNT-ANSI*"><code class="varname">CUSTOM:*SEQUENCE-COUNT-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.</li><li class="listitem">Setting <a class="link" href="#pathmerge" title="19.5.4. Function MERGE-PATHNAMES"><code class="varname">CUSTOM:*MERGE-PATHNAMES-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.</li><li class="listitem">Setting <a class="link" href="#parsename" title="19.5.3. Function PARSE-NAMESTRING"><code class="varname">CUSTOM:*PARSE-NAMESTRING-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.</li><li class="listitem">Setting <a class="link" href="#flocont" title="12.2.4.1. Rule of Float Precision Contagion sec_12-1-4-4"><code class="varname">CUSTOM:*FLOATING-POINT-CONTAGION-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.</li><li class="listitem">Setting <a class="link" href="#floratcont" title="12.2.4.2. Rule of Float and Rational Contagion sec_12-1-4-1"><code class="varname">CUSTOM:*FLOATING-POINT-RATIONAL-CONTAGION-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.</li><li class="listitem">Setting <a class="link" href="#phasecont" title="Variable CUSTOM:*PHASE-ANSI*"><code class="varname">CUSTOM:*PHASE-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.</li><li class="listitem">Setting <a class="link" href="#loop-ansi" title="6.1.3. Backward Compatibility"><code class="varname">CUSTOM:*LOOP-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.</li><li class="listitem">Setting <a class="link" href="#pr-empty-arr-ansi" title="Variable CUSTOM:*PRINT-EMPTY-ARRAYS-ANSI*"><code class="varname">CUSTOM:*PRINT-EMPTY-ARRAYS-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.</li><li class="listitem">Setting <a class="link" href="#pr-unreadable-ansi" title="Variable CUSTOM:*PRINT-UNREADABLE-ANSI*"><code class="varname">CUSTOM:*PRINT-UNREADABLE-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.</li><li class="listitem">Setting <a class="link" href="#defun-accept-spelalist" title="Variable CUSTOM:*DEFUN-ACCEPT-SPECIALIZED-LAMBDA-LIST*"><code class="varname">CUSTOM:*DEFUN-ACCEPT-SPECIALIZED-LAMBDA-LIST*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</li></ol></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>If you run <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> with the <code class="option"><a href="clisp.html#opt-ansi" class="olink">-ansi</a></code> switch or set
 the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-symbol-macro.html"><code class="classname">SYMBOL-MACRO</code></a> <a href="impnotes.html#ansi" class="olink"><code class="varname">CUSTOM:*ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> and then save <a href="impnotes.html#image" class="olink">memory image</a>,
 then all subsequent invocations of <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> with this image
 will be as if with <code class="option"><a href="clisp.html#opt-ansi" class="olink">-ansi</a></code>
 (regardless whether you actually supply the <code class="option"><a href="clisp.html#opt-ansi" class="olink">-ansi</a></code> switch).
 You can always set the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-symbol-macro.html"><code class="classname">SYMBOL-MACRO</code></a> <a href="impnotes.html#ansi" class="olink"><code class="varname">CUSTOM:*ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, or invoke
 <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> with the <code class="option"><a href="clisp.html#opt-traditional" class="olink">-traditional</a></code> switch, reversing the above
 settings, i.e.,</p></div><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">Setting <a class="link" href="#pathprint" title="22.6.1. Printing Pathnames sec_22-1-3-11"><code class="varname">CUSTOM:*PRINT-PATHNAMES-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</li><li class="listitem">Setting <a class="link" href="#spacecharprint" title="22.3. Printing Characters sec_22-1-3-2"><code class="varname">CUSTOM:*PRINT-SPACE-CHAR-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</li><li class="listitem">Setting <a class="link" href="#fixnum-char-ansi" title="Function COERCE"><code class="varname">CUSTOM:*COERCE-FIXNUM-CHAR-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</li><li class="listitem">Setting <a class="link" href="#count-ansi" title="Variable CUSTOM:*SEQUENCE-COUNT-ANSI*"><code class="varname">CUSTOM:*SEQUENCE-COUNT-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</li><li class="listitem">Setting <a class="link" href="#pathmerge" title="19.5.4. Function MERGE-PATHNAMES"><code class="varname">CUSTOM:*MERGE-PATHNAMES-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</li><li class="listitem">Setting <a class="link" href="#parsename" title="19.5.3. Function PARSE-NAMESTRING"><code class="varname">CUSTOM:*PARSE-NAMESTRING-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</li><li class="listitem">Setting <a class="link" href="#flocont" title="12.2.4.1. Rule of Float Precision Contagion sec_12-1-4-4"><code class="varname">CUSTOM:*FLOATING-POINT-CONTAGION-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</li><li class="listitem">Setting <a class="link" href="#floratcont" title="12.2.4.2. Rule of Float and Rational Contagion sec_12-1-4-1"><code class="varname">CUSTOM:*FLOATING-POINT-RATIONAL-CONTAGION-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</li><li class="listitem">Setting <a class="link" href="#phasecont" title="Variable CUSTOM:*PHASE-ANSI*"><code class="varname">CUSTOM:*PHASE-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</li><li class="listitem">Setting <a class="link" href="#loop-ansi" title="6.1.3. Backward Compatibility"><code class="varname">CUSTOM:*LOOP-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</li><li class="listitem">Setting <a class="link" href="#pr-empty-arr-ansi" title="Variable CUSTOM:*PRINT-EMPTY-ARRAYS-ANSI*"><code class="varname">CUSTOM:*PRINT-EMPTY-ARRAYS-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</li><li class="listitem">Setting <a class="link" href="#pr-unreadable-ansi" title="Variable CUSTOM:*PRINT-UNREADABLE-ANSI*"><code class="varname">CUSTOM:*PRINT-UNREADABLE-ANSI*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</li><li class="listitem">Setting <a class="link" href="#defun-accept-spelalist" title="Variable CUSTOM:*DEFUN-ACCEPT-SPECIALIZED-LAMBDA-LIST*"><code class="varname">CUSTOM:*DEFUN-ACCEPT-SPECIALIZED-LAMBDA-LIST*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.</li></ol></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="macros3"></a>31.11. Additional Fancy Macros and Functions</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#ethe">31.11.1. Macro <code class="function">EXT:ETHE</code></a></span></dt><dt><span class="section"><a href="#letf">31.11.2. Macros <code class="function">EXT:LETF</code> &amp; <code class="function">EXT:LETF*</code></a></span></dt><dt><span class="section"><a href="#memoized">31.11.3. Macro <code class="function">EXT:MEMOIZED</code></a></span></dt><dt><span class="section"><a href="#with-collect">31.11.4. Macro <code class="function">EXT:WITH-COLLECT</code></a></span></dt><dt><span class="section"><a href="#compile-time-value">31.11.5. Macro <code class="function">EXT:COMPILE-TIME-VALUE</code></a></span></dt><dt><span class="section"><a href="#with-gensyms">31.11.6. Macro <code class="function">EXT:WITH-GENSYMS</code></a></span></dt><dt><span class="section"><a href="#remove-plist">31.11.7. Function <code class="function">EXT:REMOVE-PLIST</code></a></span></dt><dt><span class="section"><a href="#html-http-output">31.11.8. Macros <code class="function">EXT:WITH-HTML-OUTPUT</code> and   <code class="function">EXT:WITH-HTTP-OUTPUT</code></a></span></dt><dt><span class="section"><a href="#open-http">31.11.9. Function <code class="function">EXT:OPEN-HTTP</code> and   macro <code class="function">EXT:WITH-HTTP-INPUT</code></a></span></dt><dt><span class="section"><a href="#http-log-stream">31.11.10. Variable <code class="varname">CUSTOM:*HTTP-LOG-STREAM*</code></a></span></dt><dt><span class="section"><a href="#browse-url">31.11.11. Function <code class="function">EXT:BROWSE-URL</code></a></span></dt><dt><span class="section"><a href="#http-proxy">31.11.12. Variable <code class="varname">CUSTOM:*HTTP-PROXY*</code></a></span></dt><dt><span class="section"><a href="#canonicalize">31.11.13. Function <code class="function">EXT:CANONICALIZE</code></a></span></dt></dl></div><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> comes with some extension macros, mostly defined in the
 file <a class="link" href="#macros3-lisp"><code class="filename">macros3.lisp</code></a> and loaded from the file <a class="link" href="#init-lisp"><code class="filename">init.lisp</code></a> during <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/make.html"><span class="command"><strong>make</strong></span></a>:</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="ethe"></a>31.11.1. Macro <a class="link" href="#ethe" title="31.11.1. Macro EXT:ETHE"><code class="function">EXT:ETHE</code></a></h3></div></div></div><p><code class="code">(<a class="link" href="#ethe" title="31.11.1. Macro EXT:ETHE"><code class="function">EXT:ETHE</code></a> <em class="replaceable"><code>value-type</code></em> <em class="replaceable"><code>form</code></em>)</code>
 enforces a type check in both interpreted and compiled code.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="letf"></a>31.11.2. Macros <a class="link" href="#letf" title="31.11.2. Macros EXT:LETF &amp; EXT:LETF*"><code class="function">EXT:LETF</code></a> &amp; <a class="link" href="#letf" title="31.11.2. Macros EXT:LETF &amp; EXT:LETF*"><code class="function">EXT:LETF*</code></a></h3></div></div></div><p>These macros are similar to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET*</code></a>, respectively,
 except that they can bind <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a>s, even <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a>s with <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_m.html#multiple_values">multiple values</a>.
 Example:
</p><pre class="programlisting">(letf (((values a b) form)) ...)
</pre><p>
is equivalent to
</p><pre class="programlisting">(multiple-value-bind (a b) form ...)
</pre><p>
while
</p><pre class="programlisting">(letf (((first l) 7)) ...)
</pre><p>
is approximately equivalent to
</p><pre class="programlisting">
 (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET*</code></a> ((#:g1 l) (#:g2 (first #:g1)))
   (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_unwind-protect.html" target="_top"><code class="function">UNWIND-PROTECT</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_progn.html" target="_top"><code class="function">PROGN</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (first #:g1) 7) ...)
      (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (first #:g1) #:g2)))
</pre></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="memoized"></a>31.11.3. Macro <code class="function">EXT:MEMOIZED</code></h3></div></div></div><p><code class="code">(<code class="function">EXT:MEMOIZED</code> <em class="replaceable"><code>form</code></em>)</code>
 memoizes the <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#primary_value">primary value</a> of <em class="replaceable"><code>form</code></em> from its first evaluation.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="with-collect"></a>31.11.4. Macro <a class="link" href="#with-collect" title="31.11.4. Macro EXT:WITH-COLLECT"><code class="function">EXT:WITH-COLLECT</code></a></h3></div></div></div><p>Similar to the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_loop.html" target="_top"><code class="function">LOOP</code></a>'s
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_6-1-3.html"><code class="literal">COLLECT</code></a>
 construct, except that it is looks more "Lispy" and can appear
 arbitrarily deep.  It defines local macros (with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_fletcm_scm_macrolet.html" target="_top"><code class="function">MACROLET</code></a>) which
 collect objects given to it into lists, which are then returned as
 <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_m.html#multiple_values">multiple values</a>.  E.g., </p><pre class="programlisting">
(ext:with-collect (c0 c1)
  (dotimes (i 10) (if (oddp i) (c0 i) (c1 i))))
⇒ <code class="computeroutput">(1 3 5 7 9)</code> ;
⇒ <code class="computeroutput">(0 2 4 6 8)</code>
</pre><p> returns two <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>s as <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_m.html#multiple_values">multiple values</a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="compile-time-value"></a>31.11.5. Macro <code class="function">EXT:COMPILE-TIME-VALUE</code></h3></div></div></div><p>Sometimes one may want to call an expensive function at
 compilation time and write the <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#primary_value">primary value</a> into the <code class="filename">#P".fas"</code> file,
 thus speeding up loading the <code class="filename">#P".fas"</code> file.
 E.g., let your file <code class="filename">primes.lisp</code> be
 </p><pre class="programlisting">
(defun primes-list (limit)
  "Return the list of all primes smaller than LIMIT."
  ...)
(defvar *all-primes* (compile-time-value (primes-list <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_most-p_ative-fixnum.html" target="_top"><code class="constant">MOST-POSITIVE-FIXNUM</code></a>)))
</pre><p>
Then </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_load.html" target="_top"><code class="function">LOAD</code></a> "primes.lisp")</code></span></dt><dd>will <span class="strong"><strong>not</strong></span> call <code class="function">primes-list</code>
    and <code class="varname">*all-primes*</code> will be <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
 </dd><dt><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile-file.html" target="_top"><code class="function">COMPILE-FILE</code></a> "primes.lisp")</code></span></dt><dd>will call <code class="function">primes-list</code> (and
    will probably take a long time) and will write the resulting list
    into <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile-file-pathname.html" target="_top"><code class="function">COMPILE-FILE-PATHNAME</code></a> "primes.lisp")</code>
 </dd><dt><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_load.html" target="_top"><code class="function">LOAD</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile-file-pathname.html" target="_top"><code class="function">COMPILE-FILE-PATHNAME</code></a>
    "primes.lisp"))</code></span></dt><dd>will <span class="strong"><strong>not</strong></span> call <code class="function">primes-list</code>
    but <code class="varname">*all-primes*</code> will be the list computed during
    compilation.</dd></dl></div><p>An alternative is to save a <a href="impnotes.html#image" class="olink">memory image</a>, which is faster than <code class="filename">#P".fas"</code>
 file but <a class="link" href="#image-portability" title="31.2.1. Image Portability">less portable</a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="with-gensyms"></a>31.11.6. Macro <code class="function">EXT:WITH-GENSYMS</code></h3></div></div></div><p>Similar to its namesake from
 <a class="ulink" href="http://www.paulgraham.com/" target="_top">Paul Graham</a>'s book
 <a class="ulink" href="http://www.paulgraham.com/onlisp.html" target="_top"><span class="quote">“<span class="quote">On
  Lisp</span>”</span></a>, this macro is useful for writing other macros:
</p><pre class="programlisting">
(with-gensyms ("FOO-" bar baz zot) ...)
</pre><p>
expands to
</p><pre class="programlisting">
(let ((bar (gensym "FOO-BAR-"))
      (baz (gensym "FOO-BAZ-"))
      (zot (gensym "FOO-ZOT-")))
  ...)
</pre><p>
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="remove-plist"></a>31.11.7. Function <code class="function">EXT:REMOVE-PLIST</code></h3></div></div></div><p>Similar to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_removecm__elete-if-not.html" target="_top"><code class="function">REMOVE</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_remf.html" target="_top"><code class="function">REMF</code></a>, this function removes some
 properties from a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#property_list">property list</a>.  It is non-destructive and thus can be
 used on <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> arguments to remove some keyword parameters, e.g.,
</p><pre class="programlisting">
(defmacro with-foo ((<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> foo1 foo2) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> body)
  `(... ,foo1 ... ,foo2 ... ,@body))
(defmacro with-foo-bar ((<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> opts <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> bar1 bar2
                         <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;ALLOW-OTHER-KEYS</code></a>)
                        <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> body)
  `(with-foo (,@(remove-plist opts :bar1 :bar2)
     ... ,bar1 ... ,bar2 ... ,@body)))
(defun foo-bar ()
  (with-foo-bar (:bar1 1 :foo2 2) ...))
</pre><p>
here <code class="function">WITH-FOO</code> does not receive the
<code class="literal">:BAR1 1</code> argument from <code class="function">FOO-BAR</code>.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="html-http-output"></a>31.11.8. Macros <code class="function">EXT:WITH-HTML-OUTPUT</code> and
  <code class="function">EXT:WITH-HTTP-OUTPUT</code></h3></div></div></div><p>Defined in <a class="link" href="#inspect-lisp"><code class="filename">inspect.lisp</code></a>, these macros are useful
 for the rudimentary <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> server defined there.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="open-http"></a>31.11.9. Function <a class="link" href="#open-http" title="31.11.9. Function EXT:OPEN-HTTP and macro EXT:WITH-HTTP-INPUT"><code class="function">EXT:OPEN-HTTP</code></a> and
  macro <code class="function">EXT:WITH-HTTP-INPUT</code></h3></div></div></div><p>Defined in
 <a class="link" href="#clhs-lisp"><code class="filename">clhs.lisp</code></a>,
 they allow downloading data over the Internet using the <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> protocol.
 <code class="code">(<a class="link" href="#open-http" title="31.11.9. Function EXT:OPEN-HTTP and macro EXT:WITH-HTTP-INPUT"><code class="function">EXT:OPEN-HTTP</code></a> url <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:IF-DOES-NOT-EXIST</code> :LOG)</code> opens
 a <a class="link" href="#socket" title="32.4. Socket Streams">socket</a> connection to the <em class="replaceable"><code>url</code></em> host,
 sends the <span class="command"><strong>GET</strong></span> request,
 and returns two values: the <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-STREAM</code></a> and content length.
<code class="code">(EXT:WITH-HTTP-INPUT (<em class="replaceable"><code>variable</code></em> url) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> body)</code> binds <em class="replaceable"><code>variable</code></em>
to the <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-STREAM</code></a> returned by <a class="link" href="#open-http" title="31.11.9. Function EXT:OPEN-HTTP and macro EXT:WITH-HTTP-INPUT"><code class="function">EXT:OPEN-HTTP</code></a> and executes the <em class="replaceable"><code>body</code></em>.
<code class="code">(EXT:WITH-HTTP-INPUT ((<em class="replaceable"><code>variable</code></em> <em class="replaceable"><code>contents</code></em>) url) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> body)</code>
additionally binds <em class="replaceable"><code>contents</code></em> to the content length.</p><p><a class="link" href="#open-http" title="31.11.9. Function EXT:OPEN-HTTP and macro EXT:WITH-HTTP-INPUT"><code class="function">EXT:OPEN-HTTP</code></a> will check <a class="link" href="#http-proxy" title="31.11.12. Variable CUSTOM:*HTTP-PROXY*"><code class="varname">CUSTOM:*HTTP-PROXY*</code></a> on startup and parse the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html">environment variable</a>
 <code class="envar">HTTP_PROXY</code> if <a class="link" href="#http-proxy" title="31.11.12. Variable CUSTOM:*HTTP-PROXY*"><code class="varname">CUSTOM:*HTTP-PROXY*</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</p><p>The <code class="constant">:LOG</code> argument binds <a class="link" href="#http-log-stream" title="31.11.10. Variable CUSTOM:*HTTP-LOG-STREAM*"><code class="varname">CUSTOM:*HTTP-LOG-STREAM*</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="http-log-stream"></a>31.11.10. Variable <a class="link" href="#http-log-stream" title="31.11.10. Variable CUSTOM:*HTTP-LOG-STREAM*"><code class="varname">CUSTOM:*HTTP-LOG-STREAM*</code></a></h3></div></div></div><p>Function <a class="link" href="#open-http" title="31.11.9. Function EXT:OPEN-HTTP and macro EXT:WITH-HTTP-INPUT"><code class="function">EXT:OPEN-HTTP</code></a> logs its actions to <a class="link" href="#http-log-stream" title="31.11.10. Variable CUSTOM:*HTTP-LOG-STREAM*"><code class="varname">CUSTOM:*HTTP-LOG-STREAM*</code></a>
  which is initially set to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stterminal-iost.html" target="_top"><code class="varname">*TERMINAL-IO*</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="browse-url"></a>31.11.11. Function <a class="link" href="#browse-url" title="31.11.11. Function EXT:BROWSE-URL"><code class="function">EXT:BROWSE-URL</code></a></h3></div></div></div><p>Function <code class="code">(<a class="link" href="#browse-url" title="31.11.11. Function EXT:BROWSE-URL"><code class="function">EXT:BROWSE-URL</code></a> url <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <a class="link" href="#browse-url" title="31.11.11. Function EXT:BROWSE-URL"><code class="constant">:BROWSER</code></a> <code class="constant">:OUT</code>)</code>
  calls a browser on the URL. <em class="replaceable"><code>browser</code></em>
  (defaults to <a class="link" href="#browse-url" title="31.11.11. Function EXT:BROWSE-URL"><code class="varname">CUSTOM:*BROWSER*</code></a>) should be a valid keyword in the <a class="link" href="#browse-url" title="31.11.11. Function EXT:BROWSE-URL"><code class="constant">CUSTOM:*BROWSERS*</code></a> <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_a.html#association_list">association list</a>.
  <code class="constant">:OUT</code> specifies the stream where the progress messages are printed
  (defaults to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-OUTPUT*</code></a>).
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="http-proxy"></a>31.11.12. Variable <a class="link" href="#http-proxy" title="31.11.12. Variable CUSTOM:*HTTP-PROXY*"><code class="varname">CUSTOM:*HTTP-PROXY*</code></a></h3></div></div></div><p>If you are behind a proxy server, you will need to set <a class="link" href="#http-proxy" title="31.11.12. Variable CUSTOM:*HTTP-PROXY*"><code class="varname">CUSTOM:*HTTP-PROXY*</code></a> to
 a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> <span class="data"><code class="literal">(name:password host port)</code></span>.
 By default, the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html">environment variable</a> <code class="envar">http_proxy</code> is used, the
 expected format is <span class="data"><code class="literal">"name:password@host:port"</code></span>.
 If no <span class="data"><code class="literal">#\@</code></span> is present,
 <em class="replaceable"><code>name</code></em> and <em class="replaceable"><code>password</code></em> are <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
 If no <span class="data"><code class="literal">#\:</code></span> is present,
 <em class="replaceable"><code>password</code></em> (or <em class="replaceable"><code>port</code></em>) is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</p><p>Use function <code class="code">(EXT:HTTP-PROXY <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>
  (<a class="link" href="#getenv" title="32.8. Operating System Environment"><code class="function">EXT:GETENV</code></a> "http_proxy")))</code> to reset
  <a class="link" href="#http-proxy" title="31.11.12. Variable CUSTOM:*HTTP-PROXY*"><code class="varname">CUSTOM:*HTTP-PROXY*</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="canonicalize"></a>31.11.13. Function <a class="link" href="#canonicalize" title="31.11.13. Function EXT:CANONICALIZE"><code class="function">EXT:CANONICALIZE</code></a></h3></div></div></div><p>If you want to canonicalize a <em class="replaceable"><code>value</code></em> before further processing it, you
 can pass it to <a class="link" href="#canonicalize" title="31.11.13. Function EXT:CANONICALIZE"><code class="function">EXT:CANONICALIZE</code></a> together with a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_sequence.html" target="_top"><code class="classname">SEQUENCE</code></a> of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_function.html" target="_top"><code class="classname">FUNCTION</code></a>s:
 <code class="code">(<a class="link" href="#canonicalize" title="31.11.13. Function EXT:CANONICALIZE"><code class="function">EXT:CANONICALIZE</code></a> <em class="replaceable"><code>value</code></em> <em class="replaceable"><code>functions</code></em>
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> (test '<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eql.html" target="_top"><code class="function">EQL</code></a>) (max-iter 1024))</code> will call <em class="replaceable"><code>function</code></em>s on
 <em class="replaceable"><code>value</code></em> until it stabilizes under <em class="replaceable"><code>test</code></em>
 (which should be a valid <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_hash-table-test.html" target="_top"><code class="function">HASH-TABLE-TEST</code></a>) and return the stabilized
 value and the number of iterations the stabilization required.</p><p>E.g., <span class="module"><a href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/clx/new-clx/"><code class="filename">clx/new-clx</code></a></span> uses it together with
 <strong class="first"><em class="firstterm"><code class="varname">XLIB:*CANONICALIZE-ENCODING*</code></em></strong>
 to fix the broken encoding names returned by the <a class="ulink" href="http://www.x.org/" target="_top">X Window System</a> (e.g., convert
 <code class="literal">"iso8859-1"</code> to <code class="literal">"ISO-8859-1"</code>)
 before passing them over to <a class="link" href="#make-encoding" title="31.5.4. Function EXT:MAKE-ENCODING"><code class="function">EXT:MAKE-ENCODING</code></a>. If you encounter an <a class="link" href="#encoding" title="31.5. Encodings"><code class="classname">EXT:ENCODING</code></a>
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> in <span class="module"><a href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/clx/new-clx/"><code class="filename">clx/new-clx</code></a></span>, you can augment this variable to avoid it.
</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="customize"></a>31.12. Customizing <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> behavior</h2></div></div></div><p>The user-customizable variables and functions are located in the
 package <a class="link" href="#customize" title="31.12. Customizing CLISP behavior"><strong class="package"><span class="quote">“<span class="quote">CUSTOM</span>”</span></strong></a> and thus can be listed using
 <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_aproposcm_apropos-list.html" target="_top"><code class="function">APROPOS</code></a> "" "CUSTOM")</code>:
 </p><table border="0" summary="Simple list" class="simplelist"><tr><td><a href="impnotes.html#ansi" class="olink"><code class="varname">CUSTOM:*ANSI*</code></a></td><td><code class="varname">CUSTOM:*APPLYHOOK*</code></td></tr><tr><td><a class="link" href="#apropos" title="25.2.10. Functions APROPOS &amp; APROPOS-LIST"><code class="varname">CUSTOM:*APROPOS-DO-MORE*</code></a></td><td><a class="link" href="#apropos" title="25.2.10. Functions APROPOS &amp; APROPOS-LIST"><code class="varname">CUSTOM:*APROPOS-MATCHER*</code></a></td></tr><tr><td><code class="varname">CUSTOM:*BREAK-ON-WARNINGS*</code></td><td><a class="link" href="#browse-url" title="31.11.11. Function EXT:BROWSE-URL"><code class="varname">CUSTOM:*BROWSER*</code></a></td></tr><tr><td><a class="link" href="#browse-url" title="31.11.11. Function EXT:BROWSE-URL"><code class="constant">CUSTOM:*BROWSERS*</code></a></td><td><a href="impnotes.html#clhs-root" class="olink"><code class="function">CUSTOM:CLHS-ROOT</code></a></td></tr><tr><td><a class="link" href="#clhs-root" title="Function CUSTOM:CLHS-ROOT"><code class="varname">CUSTOM:*CLHS-ROOT-DEFAULT*</code></a></td><td><a class="link" href="#fixnum-char-ansi" title="Function COERCE"><code class="varname">CUSTOM:*COERCE-FIXNUM-CHAR-ANSI*</code></a></td></tr><tr><td><a class="link" href="#compile-warn"><code class="varname">CUSTOM:*COMPILE-WARNINGS*</code></a></td><td><a class="link" href="#compiled-types"><code class="varname">CUSTOM:*COMPILED-FILE-TYPES*</code></a></td></tr><tr><td><a href="impnotes.html#language" class="olink"><code class="varname">CUSTOM:*CURRENT-LANGUAGE*</code></a></td><td><a href="impnotes.html#def-file-enc" class="olink"><code class="varname">CUSTOM:*DEFAULT-FILE-ENCODING*</code></a></td></tr><tr><td><a class="link" href="#default-float-format" title="Variable CUSTOM:*DEFAULT-FLOAT-FORMAT*"><code class="varname">CUSTOM:*DEFAULT-FLOAT-FORMAT*</code></a></td><td><a class="link" href="#default-tz" title="Default Time Zone"><code class="varname">CUSTOM:*DEFAULT-TIME-ZONE*</code></a></td></tr><tr><td><code class="varname">CUSTOM:*DEFTYPE-DEPTH-LIMIT*</code></td><td><a class="link" href="#defun-accept-spelalist" title="Variable CUSTOM:*DEFUN-ACCEPT-SPECIALIZED-LAMBDA-LIST*"><code class="varname">CUSTOM:*DEFUN-ACCEPT-SPECIALIZED-LAMBDA-LIST*</code></a></td></tr><tr><td><a class="link" href="#device-prefix"><code class="varname">CUSTOM:*DEVICE-PREFIX*</code></a></td><td><a class="link" href="#ed" title="25.2.9. Function ED"><code class="varname">CUSTOM:*EDITOR*</code></a></td></tr><tr><td><a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="varname">CUSTOM:*EQ-HASHFUNCTION*</code></a></td><td><a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="varname">CUSTOM:*EQL-HASHFUNCTION*</code></a></td></tr><tr><td><a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="varname">CUSTOM:*EQUAL-HASHFUNCTION*</code></a></td><td><code class="varname">CUSTOM:*ERROR-HANDLER*</code></td></tr><tr><td><code class="varname">CUSTOM:*EVALHOOK*</code></td><td><a href="impnotes.html#fill-stream" class="olink"><code class="varname">CUSTOM:*FILL-INDENT-SEXP*</code></a></td></tr><tr><td><a class="link" href="#fini-hooks" title="31.1.3. Customizing Termination"><code class="varname">CUSTOM:*FINI-HOOKS*</code></a></td><td><a class="link" href="#flocont" title="12.2.4.1. Rule of Float Precision Contagion sec_12-1-4-4"><code class="varname">CUSTOM:*FLOATING-POINT-CONTAGION-ANSI*</code></a></td></tr><tr><td><a class="link" href="#floratcont" title="12.2.4.2. Rule of Float and Rational Contagion sec_12-1-4-1"><code class="varname">CUSTOM:*FLOATING-POINT-RATIONAL-CONTAGION-ANSI*</code></a></td><td><a href="impnotes.html#foreign-enc" class="olink"><code class="varname">CUSTOM:*FOREIGN-ENCODING*</code></a></td></tr><tr><td><a class="link" href="#http-log-stream" title="31.11.10. Variable CUSTOM:*HTTP-LOG-STREAM*"><code class="varname">CUSTOM:*HTTP-LOG-STREAM*</code></a></td><td><a class="link" href="#http-proxy" title="31.11.12. Variable CUSTOM:*HTTP-PROXY*"><code class="varname">CUSTOM:*HTTP-PROXY*</code></a></td></tr><tr><td><a href="impnotes.html#impnotes-root" class="olink"><code class="function">CUSTOM:IMPNOTES-ROOT</code></a></td><td><a class="link" href="#impnotes-root" title="Function CUSTOM:IMPNOTES-ROOT"><code class="varname">CUSTOM:*IMPNOTES-ROOT-DEFAULT*</code></a></td></tr><tr><td><a href="impnotes.html#init-hooks" class="olink"><code class="varname">CUSTOM:*INIT-HOOKS*</code></a></td><td><a class="link" href="#inspect" title="25.2.7. Function INSPECT"><code class="varname">CUSTOM:*INSPECT-BROWSER*</code></a></td></tr><tr><td><a class="link" href="#inspect" title="25.2.7. Function INSPECT"><code class="varname">CUSTOM:*INSPECT-FRONTEND*</code></a></td><td><a class="link" href="#inspect" title="25.2.7. Function INSPECT"><code class="varname">CUSTOM:*INSPECT-LENGTH*</code></a></td></tr><tr><td><a class="link" href="#inspect" title="25.2.7. Function INSPECT"><code class="varname">CUSTOM:*INSPECT-PRINT-LENGTH*</code></a></td><td><a class="link" href="#inspect" title="25.2.7. Function INSPECT"><code class="varname">CUSTOM:*INSPECT-PRINT-LEVEL*</code></a></td></tr><tr><td><a class="link" href="#inspect" title="25.2.7. Function INSPECT"><code class="varname">CUSTOM:*INSPECT-PRINT-LINES*</code></a></td><td><a href="clisp.html#opt-libdir" class="olink"><code class="varname">CUSTOM:*LIB-DIRECTORY*</code></a></td></tr><tr><td><a href="impnotes.html#load-comp" class="olink"><code class="varname">CUSTOM:*LOAD-COMPILING*</code></a></td><td><a href="impnotes.html#load-echo" class="olink"><code class="varname">CUSTOM:*LOAD-ECHO*</code></a></td></tr><tr><td><a href="impnotes.html#load-lpt" class="olink"><code class="varname">CUSTOM:*LOAD-LOGICAL-PATHNAME-TRANSLATIONS-DATABASE*</code></a></td><td><a class="link" href="#load-obs"><code class="varname">CUSTOM:*LOAD-OBSOLETE-ACTION*</code></a></td></tr><tr><td><a href="impnotes.html#load-paths" class="olink"><code class="varname">CUSTOM:*LOAD-PATHS*</code></a></td><td><a class="link" href="#loop-ansi" title="6.1.3. Backward Compatibility"><code class="varname">CUSTOM:*LOOP-ANSI*</code></a></td></tr><tr><td><a class="link" href="#pathmerge" title="19.5.4. Function MERGE-PATHNAMES"><code class="varname">CUSTOM:*MERGE-PATHNAMES-ANSI*</code></a></td><td><a href="impnotes.html#misc-enc" class="olink"><code class="varname">CUSTOM:*MISC-ENCODING*</code></a></td></tr><tr><td><a class="link" href="#module-providers" title="24.3.3. User variable CUSTOM::*MODULE-PROVIDER-FUNCTIONS*"><code class="varname">CUSTOM::*MODULE-PROVIDER-FUNCTIONS*</code></a></td><td><code class="varname">CUSTOM:*PACKAGE-TASKS-TREAT-SPECIALLY*</code></td></tr><tr><td><a class="link" href="#parsename" title="19.5.3. Function PARSE-NAMESTRING"><code class="varname">CUSTOM:*PARSE-NAMESTRING-ANSI*</code></a></td><td><a class="link" href="#name-type-split" title="Name/type namestring split"><code class="varname">CUSTOM:*PARSE-NAMESTRING-DOT-FILE*</code></a></td></tr><tr><td><a href="impnotes.html#path-enc" class="olink"><code class="varname">CUSTOM:*PATHNAME-ENCODING*</code></a></td><td><a class="link" href="#phasecont" title="Variable CUSTOM:*PHASE-ANSI*"><code class="varname">CUSTOM:*PHASE-ANSI*</code></a></td></tr><tr><td><a class="link" href="#ppr-first-newline" title="Variable CUSTOM:*PPRINT-FIRST-NEWLINE*"><code class="varname">CUSTOM:*PPRINT-FIRST-NEWLINE*</code></a></td><td><a class="link" href="#pr-closure" title="Variable CUSTOM:*PRINT-CLOSURE*"><code class="varname">CUSTOM:*PRINT-CLOSURE*</code></a></td></tr><tr><td><a class="link" href="#pr-empty-arr-ansi" title="Variable CUSTOM:*PRINT-EMPTY-ARRAYS-ANSI*"><code class="varname">CUSTOM:*PRINT-EMPTY-ARRAYS-ANSI*</code></a></td><td><a class="link" href="#pr-indent" title="Variable CUSTOM:*PRINT-INDENT-LISTS*"><code class="varname">CUSTOM:*PRINT-INDENT-LISTS*</code></a></td></tr><tr><td><a class="link" href="#pr-sym-pack-prefix" title="Variable CUSTOM:*PRINT-SYMBOL-PACKAGE-PREFIX-SHORTEST*"><code class="function">CUSTOM:*PRINT-SYMBOL-PACKAGE-PREFIX-SHORTEST*</code></a></td><td><a class="link" href="#pathprint" title="22.6.1. Printing Pathnames sec_22-1-3-11"><code class="varname">CUSTOM:*PRINT-PATHNAMES-ANSI*</code></a></td></tr><tr><td><code class="varname">CUSTOM:*PRINT-PRETTY-FILL*</code></td><td><a class="link" href="#pr-rpars" title="Variable CUSTOM:*PRINT-RPARS*"><code class="varname">CUSTOM:*PRINT-RPARS*</code></a></td></tr><tr><td><a class="link" href="#spacecharprint" title="22.3. Printing Characters sec_22-1-3-2"><code class="varname">CUSTOM:*PRINT-SPACE-CHAR-ANSI*</code></a></td><td><a class="link" href="#pr-unreadable-ansi" title="Variable CUSTOM:*PRINT-UNREADABLE-ANSI*"><code class="varname">CUSTOM:*PRINT-UNREADABLE-ANSI*</code></a></td></tr><tr><td><a class="link" href="#prompt-body"><code class="varname">CUSTOM:*PROMPT-BODY*</code></a></td><td><a class="link" href="#prompt-break"><code class="varname">CUSTOM:*PROMPT-BREAK*</code></a></td></tr><tr><td><a class="link" href="#prompt-finish"><code class="varname">CUSTOM:*PROMPT-FINISH*</code></a></td><td><a class="link" href="#prompt-start"><code class="varname">CUSTOM:*PROMPT-START*</code></a></td></tr><tr><td><a class="link" href="#prompt-step"><code class="varname">CUSTOM:*PROMPT-STEP*</code></a></td><td><a class="link" href="#reopen" title="Variable CUSTOM:*REOPEN-OPEN-FILE*"><code class="varname">CUSTOM:*REOPEN-OPEN-FILE*</code></a></td></tr><tr><td><a href="impnotes.html#err-pr-bt" class="olink"><code class="varname">CUSTOM:*REPORT-ERROR-PRINT-BACKTRACE*</code></a></td><td><a href="impnotes.html#image" class="olink"><code class="varname">CUSTOM:*SAVEINITMEM-VERBOSE*</code></a></td></tr><tr><td><a class="link" href="#count-ansi" title="Variable CUSTOM:*SEQUENCE-COUNT-ANSI*"><code class="varname">CUSTOM:*SEQUENCE-COUNT-ANSI*</code></a></td><td><a class="link" href="#source-types"><code class="varname">CUSTOM:*SOURCE-FILE-TYPES*</code></a></td></tr><tr><td><a class="link" href="#suppress-check-redef" title="Variable CUSTOM:*SUPPRESS-CHECK-REDEFINITION*"><code class="varname">CUSTOM:*SUPPRESS-CHECK-REDEFINITION*</code></a></td><td><a class="link" href="#defconstant-similar" title="5.5.1. Variable CUSTOM:*SUPPRESS-SIMILAR-CONSTANT-REDEFINITION-WARNING*"><code class="varname">CUSTOM:*SUPPRESS-SIMILAR-CONSTANT-REDEFINITION-WARNING*</code></a></td></tr><tr><td><a class="link" href="#pack-lock" title="11.2. Constraints on the “COMMON-LISP” Package for Conforming Programs - package locking sec_11-1-2-1-2"><code class="varname">CUSTOM:*SYSTEM-PACKAGE-LIST*</code></a></td><td><a href="impnotes.html#term-enc" class="olink"><code class="varname">CUSTOM:*TERMINAL-ENCODING*</code></a></td></tr><tr><td><a class="link" href="#trace-indent" title="Variable CUSTOM:*TRACE-INDENT*"><code class="varname">CUSTOM:*TRACE-INDENT*</code></a></td><td><a class="link" href="#user-commands" title="25.1.1. User-defined Commands"><code class="varname">CUSTOM:*USER-COMMANDS*</code></a></td></tr><tr><td><a href="clisp-link.html#opt-install" class="olink"><code class="varname">CUSTOM:*USER-LIB-DIRECTORY*</code></a></td><td><code class="varname">CUSTOM:*USER-MAIL-ADDRESS*</code></td></tr><tr><td><a class="link" href="#warn-fpc" title="Variable CUSTOM:*WARN-ON-FLOATING-POINT-CONTAGION*"><code class="varname">CUSTOM:*WARN-ON-FLOATING-POINT-CONTAGION*</code></a></td><td><a class="link" href="#hashtable-gc-rehash-warn"><code class="varname">CUSTOM:*WARN-ON-HASHTABLE-NEEDING-REHASH-AFTER-GC*</code></a></td></tr><tr><td><code class="varname">CUSTOM:*WITH-HTML-OUTPUT-DOCTYPE*</code></td><td> </td></tr></table><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>Some of these variables are
  platform-specific.</p></div><p>You should set these variables (and do whatever other
 customization you see fit) in the file <a class="link" href="#config-lisp"><code class="filename">config.lisp</code></a> in the build
 directory before building <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.
 Alternatively, after building <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>, or if you are using a binary
 distribution of <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>, you can modify <a class="link" href="#config-lisp"><code class="filename">config.lisp</code></a>, compile and load
 it, and then save the <a href="impnotes.html#image" class="olink">memory image</a>.
 Finally, you can create an <a href="clisp.html#opt-norc" class="olink">RC file</a> which is loaded whenever <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
 is started.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="code-walk"></a>31.13. Code Walker</h2></div></div></div><p>You can use function <a class="link" href="#code-walk" title="31.13. Code Walker"><code class="function">EXT:EXPAND-FORM</code></a> to expand all the macros,
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-symbol-macro.html"><code class="classname">SYMBOL-MACRO</code></a>s, etc, in a single form:
</p><pre class="programlisting">
(<a class="link" href="#code-walk" title="31.13. Code Walker"><code class="function">EXT:EXPAND-FORM</code></a> '(macrolet ((bar (x) `(print ,x)))
                    (macrolet ((baz (x) `(bar ,x)))
                      (symbol-macrolet ((z 3))
                        (baz z)))))
⇒ <code class="computeroutput">(locally (print 3))</code> <strong>	; </strong><em class="lineannotation"><span class="lineannotation">the expansion</span></em>
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a></code> <strong>	; </strong><em class="lineannotation"><span class="lineannotation">indicator: some expansion has actually been done</span></em>
</pre><p>This is sometimes called a <span class="quote">“<span class="quote">code walker</span>”</span>,
 except that a code walker would probably leave the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_fletcm_scm_macrolet.html" target="_top"><code class="function">MACROLET</code></a> and
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_symbol-macrolet.html" target="_top"><code class="function">SYMBOL-MACROLET</code></a> forms intact and just do the expansion.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>Function <a class="link" href="#code-walk" title="31.13. Code Walker"><code class="function">EXT:EXPAND-FORM</code></a> is the exported part of the
  <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> interpreter (AKA <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eval.html" target="_top"><code class="function">EVAL</code></a>), so it expands forms by assuming the
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_eval-when.html" target="_top"><code class="function">EVAL-WHEN</code></a> situation <code class="constant">:EXECUTE</code> and is therefore
  unsuitable for forms that may later be passed to the compiler:
</p><pre class="programlisting">
(<a class="link" href="#code-walk" title="31.13. Code Walker"><code class="function">EXT:EXPAND-FORM</code></a> '(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_eval-when.html" target="_top"><code class="function">EVAL-WHEN</code></a> (:COMPILE-TOPLEVEL) (foo)))
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></code> ;
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a></code>
(<a class="link" href="#code-walk" title="31.13. Code Walker"><code class="function">EXT:EXPAND-FORM</code></a> '(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_eval-when.html" target="_top"><code class="function">EVAL-WHEN</code></a> (:LOAD-TOPLEVEL) (foo)))
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></code> ;
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a></code>
</pre></div></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="ext-platform"></a>Chapter 32. Platform Specific Extensions</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#screen">32.1. Random Screen Access</a></span></dt><dt><span class="section"><a href="#modules">32.2. External Modules</a></span></dt><dd><dl><dt><span class="section"><a href="#mod-overview">32.2.1. Overview</a></span></dt><dt><span class="section"><a href="#modinit">32.2.2. Module initialization</a></span></dt><dt><span class="section"><a href="#modfini">32.2.3. Module finalization</a></span></dt><dt><span class="section"><a href="#modinfo">32.2.4. Function <code class="function">EXT:MODULE-INFO</code></a></span></dt><dt><span class="section"><a href="#mod-dynload">32.2.5. Dynamic module loading</a></span></dt><dt><span class="section"><a href="#mod-set-example">32.2.6. Example</a></span></dt><dt><span class="section"><a href="#module-tools">32.2.7. Module tools</a></span></dt><dd><dl><dt><span class="section"><a href="#modprep">32.2.7.1. Modprep</a></span></dt><dt><span class="section"><a href="#clisp-h">32.2.7.2. clisp.h</a></span></dt><dt><span class="section"><a href="#exporting">32.2.7.3. Exporting</a></span></dt></dl></dd><dt><span class="section"><a href="#mod-ffi-vs-c">32.2.8. Trade-offs: <strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong> vs. <span class="command"><strong>C</strong></span>   modules</a></span></dt><dt><span class="section"><a href="#included-modules">32.2.9. Modules included in the source distribution</a></span></dt><dd><dl><dt><span class="section"><a href="#base-modules">32.2.9.1. Base Modules</a></span></dt><dt><span class="section"><a href="#incmod-db">32.2.9.2. Database, Directory et al</a></span></dt><dt><span class="section"><a href="#incmod-kdml">32.2.9.3. Mathematics, Data Mining et al</a></span></dt><dt><span class="section"><a href="#incmod-match">32.2.9.4. Matching, File Processing et al</a></span></dt><dt><span class="section"><a href="#incmod-net">32.2.9.5. Communication, Networking</a></span></dt><dt><span class="section"><a href="#incmod-gui">32.2.9.6. Graphics</a></span></dt><dt><span class="section"><a href="#incmod-bind">32.2.9.7. Bindings</a></span></dt><dt><span class="section"><a href="#incmod-toys">32.2.9.8. Toys and Games</a></span></dt><dt><span class="section"><a href="#incmod-misc">32.2.9.9. Miscellaneous</a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="#dffi">32.3. The Foreign Function Call Facility</a></span></dt><dd><dl><dt><span class="section"><a href="#dffi-intro">32.3.1. Introduction</a></span></dt><dt><span class="section"><a href="#dffi-overview">32.3.2. Overview</a></span></dt><dt><span class="section"><a href="#dffi-types">32.3.3. (Foreign) <span class="command"><strong>C</strong></span> types</a></span></dt><dt><span class="section"><a href="#c-flavor">32.3.4. The choice of the <span class="command"><strong>C</strong></span> flavor</a></span></dt><dt><span class="section"><a href="#dffi-variables">32.3.5. Foreign variables</a></span></dt><dt><span class="section"><a href="#dffi-places">32.3.6. Operations on foreign places</a></span></dt><dt><span class="section"><a href="#dffi-functions">32.3.7. Foreign functions</a></span></dt><dd><dl><dt><span class="section"><a href="#dffi-callback-mem">32.3.7.1. Callbacks and memory management</a></span></dt></dl></dd><dt><span class="section"><a href="#allocation">32.3.8. Argument and result passing conventions</a></span></dt><dt><span class="section"><a href="#param-mode">32.3.9. Parameter Mode</a></span></dt><dt><span class="section"><a href="#dffi-examples">32.3.10. Examples</a></span></dt><dd><dl><dt><span class="section"><a href="#dffi-ex-more">32.3.10.1. More examples</a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="#socket">32.4. Socket Streams</a></span></dt><dd><dl><dt><span class="section"><a href="#socket-intro">32.4.1. Introduction</a></span></dt><dt><span class="section"><a href="#socket-api">32.4.2. Socket API Reference</a></span></dt><dt><span class="section"><a href="#timeout-k">32.4.3. Argument <code class="constant">:TIMEOUT</code></a></span></dt></dl></dd><dt><span class="section"><a href="#mt">32.5. Multiple Threads of Execution</a></span></dt><dd><dl><dt><span class="section"><a href="#mt-intro">32.5.1. Introduction</a></span></dt><dt><span class="section"><a href="#mt-general">32.5.2. General principles</a></span></dt><dd><dl><dt><span class="section"><a href="#mt-parallelizability">32.5.2.1. Parallelizability</a></span></dt><dt><span class="section"><a href="#mt-symvalue">32.5.2.2. Special Variable Values</a></span></dt><dt><span class="section"><a href="#mt-package">32.5.2.3. Packages</a></span></dt><dt><span class="section"><a href="#mt-clos">32.5.2.4. <span class="command"><strong>CLOS</strong></span></a></span></dt><dt><span class="section"><a href="#mt-mutable">32.5.2.5. Hash Tables, Sequences, and other   mutable objects</a></span></dt><dt><span class="section"><a href="#mt-unsafe">32.5.2.6. Examples of thread-unsafe code</a></span></dt></dl></dd><dt><span class="section"><a href="#mt-api">32.5.3. Thread API reference</a></span></dt></dl></dd><dt><span class="section"><a href="#quickstart">32.6. Quickstarting delivery with <span class="command"><strong>CLISP</strong></span></a></span></dt><dd><dl><dt><span class="section"><a href="#quickstart-summary">32.6.1. Summary</a></span></dt><dt><span class="section"><a href="#quickstart-unix">32.6.2. Scripting with <span class="command"><strong>CLISP</strong></span></a></span></dt><dt><span class="section"><a href="#quickstart-desktop">32.6.3. Desktop Environments</a></span></dt><dt><span class="section"><a href="#quickstart-linux">32.6.4. Associating extensions with <span class="command"><strong>CLISP</strong></span> via kernel</a></span></dt></dl></dd><dt><span class="section"><a href="#shell">32.7. Shell, Pipes and Printing</a></span></dt><dd><dl><dt><span class="section"><a href="#exec">32.7.1. Shell</a></span></dt><dt><span class="section"><a href="#pipe">32.7.2. Pipes</a></span></dt><dt><span class="section"><a href="#hardcopy">32.7.3. Printing</a></span></dt></dl></dd><dt><span class="section"><a href="#getenv">32.8. Operating System Environment</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="screen"></a>32.1. Random Screen Access</h2></div><div><h3 class="subtitle"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platforms only.</span></span></h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">(<code class="function">SCREEN:MAKE-WINDOW</code>)</code></span></dt><dd>returns a <span class="type">WINDOW-STREAM</span>.
    As long as this stream is open, the terminal is in cbreak/noecho mode.
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stterminal-iost.html" target="_top"><code class="varname">*TERMINAL-IO*</code></a> should not be used for input or output during this
    time.  (Use <a class="link" href="#with-kbd" title="21.2.2. Macro EXT:WITH-KEYBOARD"><code class="function">EXT:WITH-KEYBOARD</code></a> and <a href="impnotes.html#with-kbd" class="olink"><code class="varname">EXT:*KEYBOARD-INPUT*</code></a> instead.)
  </dd><dt><span class="term"><code class="code">(<code class="function">SCREEN:WITH-WINDOW</code> .
    <em class="replaceable"><code>body</code></em>)</code></span></dt><dd>binds
    <strong class="first"><em class="firstterm"><a class="link" href="#screen" title="32.1. Random Screen Access"><code class="varname">SCREEN:*WINDOW*</code></a><a id="scr-win" class="indexterm"></a></em></strong>
    to a <span class="type">WINDOW-STREAM</span> and executes <em class="replaceable"><code>body</code></em>.
    The stream is guaranteed to be closed when the body is left.
    During its execution, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stterminal-iost.html" target="_top"><code class="varname">*TERMINAL-IO*</code></a> should not be used, as above.
  </dd><dt><span class="term"><code class="code">(<code class="function">SCREEN:WINDOW-SIZE</code>
    <em class="replaceable"><code>window-stream</code></em>)</code></span></dt><dd>returns the window's size, as two values:
   height (= y<sub>max</sub>+1) and width (= x<sub>max</sub>+1).
  </dd><dt><span class="term"><code class="code">(<code class="function">SCREEN:WINDOW-CURSOR-POSITION</code>
    <em class="replaceable"><code>window-stream</code></em>)</code></span></dt><dd>returns the position of the cursor in the window,
   as two values: line (≥0, ≤y<sub>max</sub>, 0 means top), column
   (≥0, ≤x<sub>max</sub>, 0 means left margin).
 </dd><dt><span class="term"><code class="code">(<code class="function">SCREEN:SET-WINDOW-CURSOR-POSITION</code>
    <em class="replaceable"><code>window-stream</code></em> <em class="replaceable"><code>line</code></em> <em class="replaceable"><code>column</code></em>)</code></span></dt><dd>sets the position of the cursor in the window.
  </dd><dt><span class="term"><code class="code">(<code class="function">SCREEN:CLEAR-WINDOW</code>
    <em class="replaceable"><code>window-stream</code></em>)</code></span></dt><dd>clears the window's contents and puts the cursor
    in the upper left corner.</dd><dt><span class="term"><code class="code">(<code class="function">SCREEN:CLEAR-WINDOW-TO-EOT</code>
    <em class="replaceable"><code>window-stream</code></em>)</code></span></dt><dd>clears the window's contents from the cursor
    position to the end of window.</dd><dt><span class="term"><code class="code">(<code class="function">SCREEN:CLEAR-WINDOW-TO-EOL</code>
    <em class="replaceable"><code>window-stream</code></em>)</code></span></dt><dd>clears the window's contents from the cursor
    position to the end of line.</dd><dt><span class="term"><code class="code">(<code class="function">SCREEN:DELETE-WINDOW-LINE</code>
    <em class="replaceable"><code>window-stream</code></em>)</code></span></dt><dd>removes the cursor's line, moves the lines below
    it up by one line and clears the window's last line.
 </dd><dt><span class="term"><code class="code">(<code class="function">SCREEN:INSERT-WINDOW-LINE</code>
    <em class="replaceable"><code>window-stream</code></em>)</code></span></dt><dd>inserts a line at the cursor's line, moving the
    lines below it down by one line.</dd><dt><span class="term"><code class="code">(<code class="function">SCREEN:HIGHLIGHT-ON</code>
    <em class="replaceable"><code>window-stream</code></em>)</code></span></dt><dd>switches highlighted output on.
 </dd><dt><span class="term"><code class="code">(<code class="function">SCREEN:HIGHLIGHT-OFF</code>
    <em class="replaceable"><code>window-stream</code></em>)</code></span></dt><dd>switches highlighted output off.
 </dd><dt><span class="term"><code class="code">(<code class="function">SCREEN:WINDOW-CURSOR-ON</code>
    <em class="replaceable"><code>window-stream</code></em>)</code></span></dt><dd>makes the cursor visible, a cursor block in most
    implementations.</dd><dt><span class="term"><code class="code">(<code class="function">SCREEN:WINDOW-CURSOR-OFF</code>
    <em class="replaceable"><code>window-stream</code></em>)</code></span></dt><dd>makes the cursor invisible, in implementations
    where this is possible.</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="modules"></a>32.2. External Modules</h2></div><div><h3 class="subtitle"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platforms only.</span></span></h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mod-overview">32.2.1. Overview</a></span></dt><dt><span class="section"><a href="#modinit">32.2.2. Module initialization</a></span></dt><dt><span class="section"><a href="#modfini">32.2.3. Module finalization</a></span></dt><dt><span class="section"><a href="#modinfo">32.2.4. Function <code class="function">EXT:MODULE-INFO</code></a></span></dt><dt><span class="section"><a href="#mod-dynload">32.2.5. Dynamic module loading</a></span></dt><dt><span class="section"><a href="#mod-set-example">32.2.6. Example</a></span></dt><dt><span class="section"><a href="#module-tools">32.2.7. Module tools</a></span></dt><dd><dl><dt><span class="section"><a href="#modprep">32.2.7.1. Modprep</a></span></dt><dt><span class="section"><a href="#clisp-h">32.2.7.2. clisp.h</a></span></dt><dt><span class="section"><a href="#exporting">32.2.7.3. Exporting</a></span></dt></dl></dd><dt><span class="section"><a href="#mod-ffi-vs-c">32.2.8. Trade-offs: <strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong> vs. <span class="command"><strong>C</strong></span>   modules</a></span></dt><dt><span class="section"><a href="#included-modules">32.2.9. Modules included in the source distribution</a></span></dt><dd><dl><dt><span class="section"><a href="#base-modules">32.2.9.1. Base Modules</a></span></dt><dt><span class="section"><a href="#incmod-db">32.2.9.2. Database, Directory et al</a></span></dt><dt><span class="section"><a href="#incmod-kdml">32.2.9.3. Mathematics, Data Mining et al</a></span></dt><dt><span class="section"><a href="#incmod-match">32.2.9.4. Matching, File Processing et al</a></span></dt><dt><span class="section"><a href="#incmod-net">32.2.9.5. Communication, Networking</a></span></dt><dt><span class="section"><a href="#incmod-gui">32.2.9.6. Graphics</a></span></dt><dt><span class="section"><a href="#incmod-bind">32.2.9.7. Bindings</a></span></dt><dt><span class="section"><a href="#incmod-toys">32.2.9.8. Toys and Games</a></span></dt><dt><span class="section"><a href="#incmod-misc">32.2.9.9. Miscellaneous</a></span></dt></dl></dd></dl></div><div class="list-of-examples"><p><strong>List of Examples</strong></p><dl><dt>32.1. <a href="#mod-set-ex-bindings">Create a module set with GNU libc bindings</a></dt></dl></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="mod-win32"></a>Modules on <span class="platform">Win32</span></h3><p>Everything described in the section will work verbatim on <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>
  when using <a class="ulink" href="http://cygwin.com/" target="_top"><span class="platform">Cygwin</span></a> or <a class="ulink" href="http://www.mingw.org/" target="_top"><span class="platform">MinGW</span></a>, <span class="emphasis"><em>except</em></span> for one
  thing - you will need to replace the <code class="filename">run</code>
  extension in <code class="filename">lisp.run</code> with the <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> executable
  extension <code class="filename">exe</code>.</p><p>For historical reasons, all examples appear to assume <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> and
  use the <code class="filename">run</code> file type (<span class="quote">“<span class="quote">extension</span>”</span>)
  for the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a href="clisp.html#runtime" class="olink">runtime</a>.
  This does <span class="strong"><strong>not</strong></span> mean that they will not work on <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mod-overview"></a>32.2.1. Overview</h3></div></div></div><p><span class="emphasis"><em>External modules</em></span> are a mechanism to add
 extensions (written in <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>, for example) to <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.
 Extending <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> using an external module requires creating a <a href="impnotes.html#modset" class="olink">module set</a>
 and adding it to an existing <a href="impnotes.html#linkset" class="olink">linking set</a> using <span class="command"><strong><a href="clisp-link.html#clisp-link" class="olink">clisp-link</a></strong></span> to prodice a
 new <a href="impnotes.html#linkset" class="olink">linking set</a> which contains the extension. </p><div class="simplesect"><div class="titlepage"><div><div><h4 class="title"><a id="modset"></a>Module Set</h4></div></div></div><p>A <strong class="first"><em class="firstterm">module<a id="module" class="indexterm"></a></em></strong> is a piece of code
 (<a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> or Lisp) which defines extra (non-core) Lisp objects, symbols
 and functions. Together with <a href="impnotes.html#modset" class="olink"><span class="command"><strong>link.sh</strong></span></a>, which describes how to add the
 module to an existing <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>, it comprises a <a href="impnotes.html#modset" class="olink">module set</a>.</p><p>More formally,
 <strong class="first"><em class="firstterm"><a href="impnotes.html#modset" class="olink">module set</a><a id="modseti" class="indexterm"></a></em></strong>
 is a directory containing:
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a href="impnotes.html#modset" class="olink"><span class="command"><strong>link.sh</strong></span></a></span></dt><dd>some <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/sh.html"><span class="command"><strong>/bin/sh</strong></span></a> commands, which prepare the directory
    for linking, and set some <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html">environment variable</a>s, see <a class="xref" href="#mod-vars" title="Module set variables">the section called “Module set variables”</a>
 </dd><dt><span class="term">all other files that define the module functionality</span></dt><dd>needed by <a href="impnotes.html#modset" class="olink"><span class="command"><strong>link.sh</strong></span></a></dd></dl></div><p>In <a href="impnotes.html#modset" class="olink"><span class="command"><strong>link.sh</strong></span></a> the <a href="impnotes.html#modset" class="olink">module set</a> directory is referred to
 as <code class="varname">$modulename/</code>.</p><p>A module <strong class="first"><em class="firstterm">name<a id="module-name" class="indexterm"></a></em></strong>
 must consist of the characters <code class="filename">A</code>-<code class="filename">Z</code>,
 <code class="filename">a</code>-<code class="filename">z</code>, <code class="filename">_</code>,
 <code class="filename">0</code>-<code class="filename">9</code>.</p><p>The module name <span class="quote">“<span class="quote">clisp</span>”</span> is reserved.</p></div><div class="simplesect"><div class="titlepage"><div><div><h4 class="title"><a id="linkset"></a>Linking Set</h4></div></div></div><p>A <strong class="first"><em class="firstterm"><a href="impnotes.html#linkset" class="olink">linking set</a><a id="linkseti" class="indexterm"></a></em></strong>
 is a collection of files (<a href="clisp.html#runtime" class="olink">runtime</a>, <a href="impnotes.html#image" class="olink">memory image</a> &amp;c) which allows
 performing two major tasks:
 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Running <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>: to run a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
    contained in some <a href="impnotes.html#linkset" class="olink">linking set</a> <em class="replaceable"><code>directory</code></em>, call</p><pre class="screen">
<strong><code class="prompt">$</code></strong> <em class="replaceable"><code>directory</code></em>/lisp.run <code class="option"><a href="clisp.html#opt-memfile" class="olink">-M</a></code> <em class="replaceable"><code>directory</code></em>/lispinit.mem</pre><p>
 or </p><pre class="screen"><strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp.html#clisp" class="olink">clisp</a></strong></span> <code class="option"><a href="clisp.html#opt-link-set" class="olink">-K</a></code> <em class="replaceable"><code>directory</code></em></pre><p>
 (recommended, since it also passes
 <code class="option"><a href="clisp.html#opt-libdir" class="olink">-B</a></code>
 to the <a href="clisp.html#runtime" class="olink">runtime</a>).</p></li><li class="listitem">Adding a <a href="impnotes.html#modset" class="olink">module set</a> to create a new <a href="impnotes.html#linkset" class="olink">linking set</a> which
    will contain the module functionality.</li></ol></div><p>
 The <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> build directory contains three <a href="impnotes.html#linkset" class="olink">linking set</a>s in
 directories <span class="command"><strong>boot</strong></span>, <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>base</strong></span></a>, and <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>full</strong></span></a>, and a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
 installation normally contains two <a href="impnotes.html#linkset" class="olink">linking set</a>s: <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>base</strong></span></a>, and <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>full</strong></span></a></p><p>More formally, a <a href="impnotes.html#linkset" class="olink">linking set</a> is a directory containing at least
  these files:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="filename">lisp.run</code></span></dt><dd>the executable <a href="clisp.html#runtime" class="olink">runtime</a></dd><dt><span class="term"><a class="link" href="#image" title="31.2. Saving an Image"><code class="filename">lispinit.mem</code></a></span></dt><dd>the <a href="impnotes.html#image" class="olink">memory image</a></dd><dt><span class="term"><code class="filename">modules.h</code></span></dt><dd>the list of modules contained in this <a href="impnotes.html#linkset" class="olink">linking set</a>
</dd><dt><span class="term"><code class="filename">modules.o</code></span></dt><dd>the compiled list of modules contained in this <a href="impnotes.html#linkset" class="olink">linking set</a>
</dd><dt><a id="makevars"></a><span class="term"><code class="filename">makevars</code></span></dt><dd><p>some <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/sh.html"><span class="command"><strong>/bin/sh</strong></span></a> commands, setting the variables
   </p><div class="variablelist"><table border="0" class="variablelist"><colgroup><col align="left" valign="top" /><col /></colgroup><tbody><tr><td><p><span class="term"><code class="envar">CC</code></span></p></td><td>the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> compiler
    </td></tr><tr><td><p><span class="term"><code class="envar">CPPFLAGS</code></span></p></td><td>flags for the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> compiler, when preprocessing
       or compiling</td></tr><tr><td><p><span class="term"><code class="envar">CFLAGS</code></span></p></td><td>flags for the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> compiler, when compiling or
       linking</td></tr><tr><td><p><span class="term"><code class="envar">CLFLAGS</code></span></p></td><td>flags for the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> compiler, when linking
    </td></tr><tr><td><p><span class="term"><code class="envar">LIBS</code></span></p></td><td>libraries to use when linking (either present in
       the <a href="impnotes.html#linkset" class="olink">linking set</a> directory, or system-wide)
    </td></tr><tr><td><p><span class="term"><code class="envar">X_LIBS</code></span></p></td><td>additional <a class="ulink" href="http://www.x.org/" target="_top">X Window System</a> libraries to use
    </td></tr><tr><td><p><span class="term"><code class="envar">RANLIB</code></span></p></td><td>the ranlib command
    </td></tr><tr><td><p><span class="term"><code class="envar">FILES</code></span></p></td><td>the list of files needed when linking
    </td></tr></tbody></table></div></dd><dt><span class="term">all the <code class="envar">FILES</code></span></dt><dd>listed in <code class="filename">makevars</code>
</dd></dl></div></div><div class="simplesect"><div class="titlepage"><div><div><h4 class="title"><a id="clisp-link"></a>Manipulating <a href="impnotes.html#modset" class="olink">module set</a>s and <a href="impnotes.html#linkset" class="olink">linking set</a>s</h4></div></div></div><p>Use <span class="command"><strong><a href="clisp-link.html#clisp-link" class="olink">clisp-link</a></strong></span> to create and install <a href="impnotes.html#modset" class="olink">module set</a>s
 and add them to <a href="impnotes.html#linkset" class="olink">linking set</a>s.</p><p>See also <a class="xref" href="#mod-set-example" title="32.2.6. Example">Section 32.2.6, “Example”</a>.</p></div><div class="simplesect"><div class="titlepage"><div><div><h4 class="title"><a id="mod-vars"></a>Module set variables</h4></div></div></div><p>The following variables should be defined in <a href="impnotes.html#modset" class="olink"><span class="command"><strong>link.sh</strong></span></a>.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="envar">NEW_FILES</code></span></dt><dd>the space-separated list of object files that
  belong to the <a href="impnotes.html#modset" class="olink">module set</a> and will belong to every new <a href="impnotes.html#linkset" class="olink">linking set</a> linked
  with this <a href="impnotes.html#modset" class="olink">module set</a>.</dd><dt><span class="term"><code class="envar">NEW_LIBS</code></span></dt><dd>the space-separated list of object files, libraries or
  <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> compiler switches that need to be passed to the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>
  compiler when linking the <code class="filename">lisp.run</code> belonging to a new <a href="impnotes.html#linkset" class="olink">linking set</a>.
 </dd><dt><span class="term"><code class="envar">NEW_MODULES</code></span></dt><dd>the space-separated list of the module names
  belonging to the <a href="impnotes.html#modset" class="olink">module set</a>.  Normally, every <code class="filename">#P".c"</code> file in the
  <a href="impnotes.html#modset" class="olink">module set</a> defines a module of its own.  The module name is usually
  derived from the file name.</dd><dt><a id="mod-load"></a><span class="term"><a class="link" href="#mod-load"><code class="envar">TO_LOAD</code></a></span></dt><dd>the space-separated list of Lisp files to load
  before building the <a class="link" href="#image" title="31.2. Saving an Image"><code class="filename">lispinit.mem</code></a> belonging to a new <a href="impnotes.html#linkset" class="olink">linking set</a>.
 </dd><dt><a id="mod-preload"></a><span class="term"><a class="link" href="#mod-preload"><code class="envar">TO_PRELOAD</code></a> (optional)</span></dt><dd><p class="simpara">the space-separated list of Lisp files to load
   into an intermediate <a class="link" href="#image" title="31.2. Saving an Image"><code class="filename">lispinit.mem</code></a> file, before building the <a class="link" href="#image" title="31.2. Saving an Image"><code class="filename">lispinit.mem</code></a>
   belonging to a new <a href="impnotes.html#linkset" class="olink">linking set</a>.
   This variable is usually used to <a class="link" href="#make-pack" title="11.1.1. Function MAKE-PACKAGE">create</a>
   (or <a class="link" href="#pack-lock" title="11.2. Constraints on the “COMMON-LISP” Package for Conforming Programs - package locking sec_11-1-2-1-2">unlock</a>) the Lisp <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_package.html" target="_top"><code class="classname">PACKAGE</code></a>s which
   must be present when the new <code class="filename">#P".c"</code> files are initialized.
   E.g., the <a class="link" href="#def-call-in"><code class="function">FFI:DEF-CALL-IN</code></a> functions must reside in already defined packages;
   see <a class="xref" href="#ex-call-in" title="Example 32.7. Calling Lisp from C">Example 32.7, “Calling Lisp from <span class="command"><strong>C</strong></span>”</a>.  You can find a live example in
   <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/syscalls/preload.lisp"><code class="filename">modules/syscalls/preload.lisp</code></a>
   and <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/syscalls/link.sh.in"><code class="filename">modules/syscalls/link.sh.in</code></a>.
  </p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>If you are unlocking a package, you must also
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_removecm__elete-if-not.html" target="_top"><code class="function">DELETE</code></a> it from <a class="link" href="#pack-lock" title="11.2. Constraints on the “COMMON-LISP” Package for Conforming Programs - package locking sec_11-1-2-1-2"><code class="varname">CUSTOM:*SYSTEM-PACKAGE-LIST*</code></a> (see <a class="xref" href="#image" title="31.2. Saving an Image">Section 31.2, “Saving an Image”</a>) here
    and re-add it to <a class="link" href="#pack-lock" title="11.2. Constraints on the “COMMON-LISP” Package for Conforming Programs - package locking sec_11-1-2-1-2"><code class="varname">CUSTOM:*SYSTEM-PACKAGE-LIST*</code></a> in one of the <a class="link" href="#mod-load"><code class="envar">TO_LOAD</code></a> files.
    See, e.g., <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/i18n/preload.lisp"><code class="filename">modules/i18n/preload.lisp</code></a>
    and <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/i18n/link.sh.in"><code class="filename">modules/i18n/link.sh.in</code></a>.
</p></div></dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="modinit"></a>32.2.2. Module initialization</h3></div></div></div><p>Each module has two initialization functions:
 </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">void
    <code class="function">module__<em class="replaceable"><code>name</code></em>__init_function_1</code>
    (struct module_t* module)</span></dt><dd><p class="simpara">called only <span class="emphasis"><em>once</em></span> when <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
  discovers while loading a <a href="impnotes.html#image" class="olink">memory image</a> that there is a module present
  in the executable (<code class="filename">lisp.run</code>) which was not present at the time the
  image was saved.  It can be used to create Lisp objects,
  e.g. functions or keywords, and is indeed used for that purpose by
  <a class="link" href="#modprep-file"><span class="command"><strong>modprep</strong></span></a>.</p><p class="simpara">You do <span class="strong"><strong>not</strong></span> have to define this function yourself;
  <a class="link" href="#modprep-file"><span class="command"><strong>modprep</strong></span></a> and <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> will do that for you.</p><p class="simpara">If you use <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>, <code class="code">(<a class="link" href="#c-lines"><code class="function">FFI:C-LINES</code></a> :init-once ...)</code>
  will add code to this function.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>The <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_package.html" target="_top"><code class="classname">PACKAGE</code></a>s must already exist and be unlocked,
   cf. <a class="link" href="#mod-preload"><code class="envar">TO_PRELOAD</code></a>.</p></div><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>If you are using <a class="link" href="#modprep-file"><span class="command"><strong>modprep</strong></span></a> <span class="strong"><strong>and</strong></span> defining your
   own <span class="quote">“<span class="quote">init-once</span>”</span> function, it must call the
   <code class="function">module__<em class="replaceable"><code>name</code></em>__init_function_1__modprep</code>
   function!</p></div></dd><dt><span class="term">void <code class="function">module__<em class="replaceable"><code>name</code></em>__init_function_2</code>
  (struct module_t* module)</span></dt><dd><p class="simpara">called <span class="emphasis"><em>every time</em></span> <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> starts.
  It can be used to bind names to foreign addresses, since the address
  will be different in each invocation of <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>, and is indeed used
  for that purpose by <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> (e.g., by <a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a>).
  It can also be used to set parameters of the libraries to which the
  module interfaces, e.g., the <span class="module"><a class="filename" href="#pcre" title="33.15. Perl Compatible Regular Expressions"><code class="filename">pcre</code></a></span> module
  sets <code class="varname">pcre_malloc</code> and <code class="varname">pcre_free</code>.
 </p><p class="simpara">You do <span class="strong"><strong>not</strong></span> have to define this function yourself;
  <a class="link" href="#modprep-file"><span class="command"><strong>modprep</strong></span></a> and <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> will do that for you.</p><p class="simpara">If you use <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>, <code class="code">(<a class="link" href="#c-lines"><code class="function">FFI:C-LINES</code></a> :init-always ...)</code>
  will add code to this function.</p></dd></dl></div><p>
<em class="replaceable"><code>name</code></em> is the <a class="link" href="#mod-overview" title="32.2.1. Overview">module name</a>.</p><p>See also <a class="xref" href="#custom-init-fini" title="31.1. Customizing CLISP Process Initialization and Termination">Section 31.1, “Customizing <span class="command"><strong>CLISP</strong></span> Process   Initialization and Termination”</a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="modfini"></a>32.2.3. Module finalization</h3></div></div></div><p>Each module has a finalization function
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term">void
   <code class="function">module__<em class="replaceable"><code>name</code></em>__fini_function</code>
   (struct module_t* module)</span></dt><dd><p class="simpara">called before exiting <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.</p><p class="simpara">You do <span class="strong"><strong>not</strong></span> have to define this function yourself;
  <a class="link" href="#modprep-file"><span class="command"><strong>modprep</strong></span></a> and <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> will do that for you.</p><p class="simpara">If you use <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>, <code class="code">(<a class="link" href="#c-lines"><code class="function">FFI:C-LINES</code></a> :fini ...)</code> will
  add code to this function.</p></dd></dl></div><p>
<em class="replaceable"><code>name</code></em> is the <a class="link" href="#mod-overview" title="32.2.1. Overview">module name</a>.</p><p>See also <a class="xref" href="#custom-init-fini" title="31.1. Customizing CLISP Process Initialization and Termination">Section 31.1, “Customizing <span class="command"><strong>CLISP</strong></span> Process   Initialization and Termination”</a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="modinfo"></a>32.2.4. Function <a class="link" href="#modinfo" title="32.2.4. Function EXT:MODULE-INFO"><code class="function">EXT:MODULE-INFO</code></a></h3></div></div></div><p>Function <code class="code">(<a class="link" href="#modinfo" title="32.2.4. Function EXT:MODULE-INFO"><code class="function">EXT:MODULE-INFO</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>name</code></em>
  <em class="replaceable"><code>verbose</code></em>)</code> allows one to inquire
 about what modules are available in the currently running image.
 When called without arguments, it returns the list of module names,
 starting with <span class="quote">“<span class="quote">clisp</span>”</span>.  When <em class="replaceable"><code>name</code></em> is supplied and
 names a module, 3 values are returned - <em class="replaceable"><code>name</code></em>,
 <em class="replaceable"><code>subr-count</code></em>,
 <em class="replaceable"><code>object-count</code></em>.
 When <em class="replaceable"><code>verbose</code></em> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the full list of
 module lisp function names written in <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> (<span class="type">Subr</span>s) and
 the full list of internal lisp objects available in <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> code
 are additionally returned for the total of 5 values.</p><p>When <em class="replaceable"><code>name</code></em> is <code class="constant">:FFI</code>, returns the list of
 shared libraries opened using <code class="constant">:LIBRARY</code>.
 When <em class="replaceable"><code>verbose</code></em> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, return the
 <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_a.html#association_list">association list</a> of DLL names and all foreign objects associated with it.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mod-dynload"></a>32.2.5. Dynamic module loading</h3></div><div><h4 class="subtitle"><span class="plat-dep">Platform Dependent: <span class="plat-dep">Only in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> built <span class="strong"><strong>without</strong></span> configure flag <code class="option"><a href="impnotes.html#mod-dynload" class="olink">--without-dynamic-modules</a></code>.</span></span></h4></div></div></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>Dynamic loading does not work on all operating systems
  (<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/dlopen.html"><code class="function">dlopen</code></a> or equivalent is required).</p></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>You will probably never need to call the function <a href="impnotes.html#mod-dynload" class="olink"><code class="function">SYS::DYNLOAD-MODULES</code></a>
  explicitly (this is why it is in <a class="link" href="#sys-pac"><strong class="package"><span class="quote">“<span class="quote">SYSTEM</span>”</span></strong></a> and not in <a class="link" href="#ext-pac"><strong class="package"><span class="quote">“<span class="quote">EXT</span>”</span></strong></a>).
  You should install your module with
  </p><pre class="screen"><strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp-link.html#clisp-link" class="olink">clisp-link</a></strong></span> <code class="option"><a href="clisp-link.html#opt-install" class="olink">install</a></code> <em class="replaceable"><code>name</code></em></pre><p>
  and load it with <code class="code">(<a href="impnotes.html#require" class="olink"><code class="function">REQUIRE</code></a> <em class="replaceable"><code>name</code></em>).</code></p></div><p>Function <code class="code">(<a href="impnotes.html#mod-dynload" class="olink"><code class="function">SYS::DYNLOAD-MODULES</code></a> <em class="replaceable"><code>filename</code></em> ({<em class="replaceable"><code>name</code></em>}+))</code>
 loads a shared object file or library containing a number of named
 external <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> modules.
 </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>This facility <span class="strong"><strong>cannot</strong></span> be used to
   access arbitrary shared libraries.  To do that, use the <code class="constant">:LIBRARY</code>
   argument to <a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> and <a class="link" href="#def-c-var"><code class="function">FFI:DEF-C-VAR</code></a> instead.</p></div><p>
</p><p>External modules for <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> are shared objects
 (dynamic libraries) that contain the
 <code class="literal">module__<em class="replaceable"><code>name</code></em>__subr_tab</code> variable, among others.
 This serves to register external functions which operate on Lisp-level
 structures with <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.</p><p>To use <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/dlopen.html"><code class="function">dlopen</code></a> with modules, you should add
 <a class="ulink" href="http://tldp.org/HOWTO/Program-Library-HOWTO/shared-libraries.html" target="_top"><code class="option">-fPIC</code></a> to the module's compilation options.
 Something like
 </p><pre class="screen"><strong><code class="prompt">$</code></strong> cc -shared -o <em class="replaceable"><code>name</code></em>.so <em class="replaceable"><code>name</code></em>.o</pre><p>
 may be needed to produce the shared object file.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mod-set-example"></a>32.2.6. Example</h3></div></div></div><div class="list-of-examples"><p><strong>List of Examples</strong></p><dl><dt>32.1. <a href="#mod-set-ex-bindings">Create a module set with GNU libc bindings</a></dt></dl></div><div class="example"><a id="mod-set-ex-bindings"></a><p class="title"><strong>Example 32.1. Create a <a href="impnotes.html#modset" class="olink">module set</a> with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a> bindings</strong></p><div class="example-contents"><p>To link in the <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> bindings for the <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a>/<a class="ulink" href="https://www.kernel.org/" target="_top"><span class="platform">Linux</span></a> operating
 system, the following steps are needed.  (Step 1 and step 2 need not be
 executed in this order.)</p><div class="procedure"><ol class="procedure" type="1"><li class="step"><p class="title"><strong>Create a new <a href="impnotes.html#modset" class="olink">module set</a></strong></p><pre class="screen"><strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp-link.html#clisp-link" class="olink">clisp-link</a></strong></span> create linux /<em class="replaceable"><code>pathname</code></em>/bindings/linux.c</pre></li><li class="step"><p class="title"><strong>Modify the newly created
  <code class="filename">linux/<a href="impnotes.html#modset" class="olink"><span class="command"><strong>link.sh</strong></span></a></code></strong></p><ol type="a" class="substeps"><li class="step"><p class="title"><strong>add <code class="option">-lm</code> to the libraries</strong></p><p>replace </p><pre class="screen">NEW_LIBS="$file_list"</pre><p>
    with </p><pre class="screen">NEW_LIBS="$file_list -lm"</pre></li><li class="step"><p class="title"><strong>load <code class="filename">linux.fas</code> before saving the
    <a href="impnotes.html#image" class="olink">memory image</a></strong></p><p>replace </p><pre class="screen">TO_LOAD=''</pre><p> with
    </p><pre class="screen">TO_LOAD='/<em class="replaceable"><code>pathname</code></em>/bindings/linux.fas'</pre></li></ol></li><li class="step"><p class="title"><strong>Compile <code class="filename">linux.lisp</code>, creating
  <code class="filename">linux.c</code></strong></p><pre class="screen"><strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp.html#clisp" class="olink">clisp</a></strong></span> <code class="option"><a href="clisp.html#opt-compile" class="olink">-c</a></code> /<em class="replaceable"><code>pathname</code></em>/bindings/linux.lisp</pre></li><li class="step"><p class="title"><strong>Create a new <a href="impnotes.html#linkset" class="olink">linking set</a></strong></p><pre class="screen"><strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp-link.html#clisp-link" class="olink">clisp-link</a></strong></span> add base base+linux linux</pre></li><li class="step"><p class="title"><strong>Run and try it</strong></p><pre class="screen"><strong><code class="prompt">$</code></strong> base+linux/lisp.run <code class="option"><a href="clisp.html#opt-memfile" class="olink">-M</a></code> base+linux/lispinit.mem <code class="option"><a href="clisp.html#opt-exec-expr" class="olink">-x</a></code> '(linux:stat "/tmp")'</pre></li></ol></div></div></div><br class="example-break" /></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="module-tools"></a>32.2.7. Module tools</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#modprep">32.2.7.1. Modprep</a></span></dt><dt><span class="section"><a href="#clisp-h">32.2.7.2. clisp.h</a></span></dt><dt><span class="section"><a href="#exporting">32.2.7.3. Exporting</a></span></dt></dl></div><p>There are some tools to facilitate easy module writing.</p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="modprep"></a>32.2.7.1. Modprep</h4></div></div></div><p>If your module is written in <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>, you can pre-process your
 sources with <a class="link" href="#modprep-file"><span class="command"><strong>modprep</strong></span></a> in the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> distribution and define lisp
 functions with the <code class="function">DEFUN</code> macro:
 </p><pre class="programlisting">
DEFUN(MY-PACKAGE:MY-FUNCTION-NAME, arg1 arg2 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> FOO BAR) {
  if (!boundp(STACK_0)) STACK_0 = fixnum(0); /* BAR */
  if (!boundp(STACK_1)) STACK_1 = fixnum(1); /* FOO */
  pushSTACK(`MY-PACKAGE::SOME-SYMBOL`); /* create a symbol in the package */
  pushSTACK(`#(:THIS :IS :A :VECTOR)`); /* some vector, created once */
  pushSTACK(``MY-PACKAGE::MY-FUNCTION-NAME``); /* double `` means FUNCTION */
  VALUES1(listof(7)); /* cons up a new list and clean up the STACK */
}</pre><p>
Then <code class="code">(MY-PACKAGE:MY-FUNCTION-NAME 'A 12 :FOO T)</code> will
 return <span class="returnvalue">(A 12 T 0 MY-PACKAGE::SOME-SYMBOL #(:THIS
  :IS :A :VECTOR) #&lt;ADD-ON-SYSTEM-FUNCTION
  MY-PACKAGE:MY-FUNCTION-NAME&gt;)</span>
(assuming you <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_export.html" target="_top"><code class="function">EXPORT</code></a>ed <code class="literal">MY-FUNCTION-NAME</code> from
 <strong class="package"><span class="quote">“<span class="quote">MY-PACKAGE</span>”</span></strong>).</p><p>Note that the arguments are passed on the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> (last argument
 being the top) which has to be cleaned up before exit.</p><p>Another useful macros are:
 </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="function">DEFVAR</code></span></dt><dd>create a GC-visible private object
  </dd><dt><span class="term"><code class="function">DEFFLAGSET</code></span></dt><dd>define a <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> function which will remove
     several flag arguments from the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> and return the combined flag
     value</dd><dt><span class="term"><code class="function">DEFCHECKER</code></span></dt><dd>define a map from <a class="ulink" href="http://gcc.gnu.org/onlinedocs/cpp/" target="_top"><span class="command"><strong>cpp</strong></span></a> constants to lisp symbols and
     functions that map between them, checking that the argument is appropriate
  </dd></dl></div><p>See <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/syscalls/calls.c"><code class="filename">modules/syscalls/calls.c</code></a>
 and other included modules for more examples and file <a class="link" href="#modprep-file"><span class="command"><strong>modprep</strong></span></a> for full
 documentation.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>If you manipulate Lisp objects, you need to watch out for
  <a class="link" href="#gc-safety" title="35.5. The burden of garbage-collection upon the rest of CLISP">GC-safety</a>.</p></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="clisp-h"></a>32.2.7.2. clisp.h</h4></div></div></div><p>If your module is written in <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>, you will probably want
 to <code class="literal">#include "clisp.h"</code> to access <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> objects.
 You will certainly need to read <a href="impnotes.html#clisp-h" class="olink"><code class="filename">"clisp.h"</code></a> and some code in
 <a class="link" href="#included-modules" title="32.2.9. Modules included in the source distribution">included modules</a>, but here are
 some important hints that you will need to keep in mind:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Lisp objects have type <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="type">object</span></a>.</li><li class="listitem">Variables of this type are invalidated by
   <a class="link" href="#gc-safety" title="35.5. The burden of garbage-collection upon the rest of CLISP">lisp memory allocation</a>
   (<code class="function">allocate_*()</code> functions) - but <span class="strong"><strong>not</strong></span> <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>
   allocations (<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/malloc.html"><code class="function">malloc</code></a> et al) - and must be saved on the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> using <a class="ulink" href="http://gcc.gnu.org/onlinedocs/cpp/" target="_top"><span class="command"><strong>cpp</strong></span></a>
   macros <code class="function">pushSTACK()</code>, <code class="function">popSTACK()</code>
   and <code class="function">skipSTACK()</code>.</li><li class="listitem">Access object slots using the
   appropriate <code class="function">TheFoo()</code> macro, e.g.,
   <code class="function">TheCons(my_cons)-&gt;Car</code>, but first check the
   type with <code class="function">consp()</code>.</li><li class="listitem">Arguments are passed on the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>, as illustrated
   in the <a class="link" href="#modprep" title="32.2.7.1. Modprep">above example</a>.</li><li class="listitem"><p class="simpara">Wrap your system calls in
   <code class="literal">begin_system_call()</code>/<code class="literal">end_system_call()</code>
   pairs.  These macros, defined in <a href="impnotes.html#clisp-h" class="olink"><code class="filename">"clisp.h"</code></a>, save and restore
   registers used by <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> which could be clobbered by a system call.
  </p><p class="simpara">If the system call could block (e.g., <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/read.html"><code class="function">read</code></a>)
   you need to use <code class="literal">begin_blocking_system_call()</code> and
   <code class="literal">end_blocking_system_call()</code> instead. This will
   allow other threads to run while yours is inside the system call.
   This means that <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion could happen while you are inside this system
   call and, thus, that all objects of type <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="type">object</span></a> are
   invalidated by the call. See also <a class="xref" href="#gc-safety" title="35.5. The burden of garbage-collection upon the rest of CLISP">Section 35.5, “The burden of garbage-collection upon the rest of <span class="command"><strong>CLISP</strong></span>”</a> and
   <a class="xref" href="#gc-mt" title="35.8. Garbage Collection and Multithreading">Section 35.8, “Garbage Collection and Multithreading”</a>.</p></li></ul></div><p>
</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="exporting"></a>32.2.7.3. Exporting</h4></div></div></div><p>If your module uses <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> to interface to a <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> library,
 you might want to make your module package <a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-SENSITIVE</code></a> and use
 <a class="link" href="#exporting-lisp"><code class="filename">exporting.lisp</code></a> in the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> distribution to make <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> forms
 and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defun.html" target="_top"><code class="function">DEFUN</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmacro.html" target="_top"><code class="function">DEFMACRO</code></a> at al export the symbols they define.
 See <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/netica/"><code class="filename">modules/netica/</code></a>,
 <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/matlab/"><code class="filename">modules/matlab/</code></a> and
 <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/bindings/"><code class="filename">modules/bindings/</code></a> for examples.</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mod-ffi-vs-c"></a>32.2.8. Trade-offs: <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> vs. <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>
  modules</h3></div></div></div><p>When deciding how to write a module: whether to use <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> or
 to stick with <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> and <a class="link" href="#modprep-file"><span class="command"><strong>modprep</strong></span></a>, one has to take into account
 several issues: </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">Speed: <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> wins</span></dt><dd><p><a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> has a noticeable overhead:
   compare <code class="function">RAWSOCK:HTONS</code> (defined
   in <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/rawsock/rawsock.c"><code class="filename">modules/rawsock/rawsock.c</code></a>)
   with </p><pre class="programlisting">
(<a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> htons (<code class="constant">:NAME</code> "htons") (<code class="constant">:LIBRARY</code> :default)
  (<code class="constant">:ARGUMENTS</code> (s ffi:short)) (<code class="constant">:RETURN-TYPE</code> ffi:short) (<a class="link" href="#c-flavor" title="32.3.4. The choice of the C flavor"><code class="constant">:LANGUAGE</code></a> :stdc))
</pre><p> and observe that <code class="function">RAWSOCK:HTONS</code> is
   almost 3 times as fast (this really does compare the <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>
   overhead to the normal lisp function call because
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/htons.html"><code class="function">htons</code></a> is computationally trivial).
   This difference will matter only if you call a simple function very
   many times, in which case it would make sense to put the loop itself
   into <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>.</p></dd><dt><span class="term">Portability: <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> wins</span></dt><dd><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> is <span class="strong"><strong>not</strong></span> as widely
     ported as <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>, so it is possible that you will face a platform
     where <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> runs but <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> is not present.</li><li class="listitem">It is much easier to handle portability in
     <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>: observe the alternative implementations
     of <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/htonl.html"><code class="function">htonl</code></a> et al in
     <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/rawsock/rawsock.c"><code class="filename">modules/rawsock/rawsock.c</code></a>.
   </li><li class="listitem">Certain <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> structures have different
     layout on different platforms, and functions may take 64-bit
     arguments on some platforms and 32-bit arguments on others; so the
     <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> code has to track those differences, while <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> will
     mostly take care of these things for you.</li></ol></div></dd><dt><span class="term">Code size: <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> wins</span></dt><dd>You need to type much fewer characters with <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>,
   and, if you use the <code class="constant">:LIBRARY</code> argument to <a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> and
   <a class="link" href="#def-c-var"><code class="function">FFI:DEF-C-VAR</code></a>, you do not need to leave your <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> session to try
   out your code.  This is a huge advantage for rapid prototyping.
</dd><dt><span class="term">UI: <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> wins</span></dt><dd>To produce a nice lispy UI (using <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> and
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>word arguments etc), you will need to write wrappers to your
   <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a>s, while in <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> you can do that directly.
   The same goes for <span class="quote">“<span class="quote">polymorphism</span>”</span>: accepting different
   argument types (like, e.g., <a class="link" href="#resolve-host"><code class="function">POSIX:RESOLVE-HOST-IPADDR</code></a> does) would require a lisp
   wrapper for <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a>s.
</dd><dt><span class="term">Learning curve: unclear</span></dt><dd><p class="simpara">If you are comfortable with <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>, you might
   find the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> module facilities (e.g., <a class="link" href="#modprep-file"><span class="command"><strong>modprep</strong></span></a>) very
   easy to use.</p><p class="simpara"><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>, on the other hand, is quite high-level,
   so, if you are more comfortable with high-level languages, you might
   find it easier to write <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> forms than <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> code.
</p></dd><dt><span class="term">Safety: unclear</span></dt><dd>One can get a segfault either way: if your
   <a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> form does not describe the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> function's
   expectations with respect to the arguments and return values
   (including <a class="link" href="#allocation" title="32.3.8. Argument and result passing conventions"><em class="replaceable"><code>ALLOCATION</code></em></a>), you will probably learn that the hard way.
   If the module is written in <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>, all the opportunities to shoot
   oneself in the foot (and other body parts) are wide open
   (although well known to most <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> users).
   However, with <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>, one has to watch
   for <a class="link" href="#gc-safety" title="35.5. The burden of garbage-collection upon the rest of CLISP">GC-safety</a> too.
</dd><dt><span class="term">System requirements: <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> wins</span></dt><dd><p>Some <a class="ulink" href="https://www.kernel.org/" target="_top"><span class="platform">Linux</span></a> distributions offer separate
 <span class="emphasis"><em>library</em></span> (containing shared libraries only)
 and <span class="emphasis"><em>development</em></span> (containing static libraries and
 <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> headers) packages.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">When <span class="emphasis"><em>developing</em></span> using <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>
  with <code class="constant">:LIBRARY</code> (and avoiding <a class="link" href="#def-c-const"><code class="function">FFI:DEF-C-CONST</code></a>), the
  <span class="emphasis"><em>development</em></span> package is <span class="strong"><strong>not</strong></span> needed.
 </li><li class="listitem">When <span class="emphasis"><em>developing</em></span> with <a class="link" href="#modprep-file"><span class="command"><strong>modprep</strong></span></a>,
  the <span class="emphasis"><em>development</em></span> package <span class="strong"><strong>is</strong></span> necessary.
 </li><li class="listitem">When <span class="emphasis"><em>distributing</em></span> module (built
  with either <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> or <a class="link" href="#modprep-file"><span class="command"><strong>modprep</strong></span></a>), only the <span class="emphasis"><em>library</em></span>
  package is needed.</li></ul></div></dd></dl></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="mod-ffi-vs-c-granularity"></a>Note</h3><p>The granularity of the
  choice is <span class="emphasis"><em>per function</em></span>: the same module can use
  both <a class="link" href="#modprep-file"><span class="command"><strong>modprep</strong></span></a> and <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>.</p></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="mod-ffi-vs-c-naming"></a>Note</h3><p>It is not a good idea to have
  both <code class="filename">foo.lisp</code> and <code class="filename">foo.c</code>
  files in a module, because if you ever add an <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> form to the
  former, <a href="impnotes.html#compilefile" class="olink"><code class="function">COMPILE-FILE</code></a> will
  <a class="link" href="#c-file-overwrite" title="Warning">overwrite</a> the latter.</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="included-modules"></a>32.2.9. Modules included in the source distribution</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#base-modules">32.2.9.1. Base Modules</a></span></dt><dt><span class="section"><a href="#incmod-db">32.2.9.2. Database, Directory et al</a></span></dt><dt><span class="section"><a href="#incmod-kdml">32.2.9.3. Mathematics, Data Mining et al</a></span></dt><dt><span class="section"><a href="#incmod-match">32.2.9.4. Matching, File Processing et al</a></span></dt><dt><span class="section"><a href="#incmod-net">32.2.9.5. Communication, Networking</a></span></dt><dt><span class="section"><a href="#incmod-gui">32.2.9.6. Graphics</a></span></dt><dt><span class="section"><a href="#incmod-bind">32.2.9.7. Bindings</a></span></dt><dt><span class="section"><a href="#incmod-toys">32.2.9.8. Toys and Games</a></span></dt><dt><span class="section"><a href="#incmod-misc">32.2.9.9. Miscellaneous</a></span></dt></dl></div><p>A few modules come with the <span class="emphasis"><em>source</em></span>
 distribution of <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> (but are not necessarily built in a
 particular <span class="emphasis"><em>binary</em></span> distribution).</p><p>To use modules, read <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/unix/INSTALL"><code class="filename">unix/INSTALL</code></a>
 and build <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> in a directory <code class="filename">build-dir</code> with,
 e.g.,</p><pre class="screen">
<strong><code class="prompt">$</code></strong> ./configure --with-module=pcre --with-module=clx/new-clx --cbc build-dir</pre><p> then run it with
</p><pre class="screen"><strong><code class="prompt">$</code></strong> ./build-dir/clisp <code class="option"><a href="clisp.html#opt-link-set" class="olink">-K</a></code> full</pre><p>
This will create a <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>base</strong></span></a> <a href="impnotes.html#linkset" class="olink">linking set</a> with modules
<span class="module"><a class="filename" href="#i18n-mod" title="33.3. Internationalization of User Programs"><code class="filename">i18n</code></a></span>, <span class="module"><a class="filename" href="#regexp-mod" title="33.4. POSIX Regular Expressions"><code class="filename">regexp</code></a></span> and <span class="module"><a class="filename" href="#syscalls" title="33.2. System Calls"><code class="filename">syscalls</code></a></span> (and maybe <span class="module"><a class="filename" href="#readline-mod" title="33.5. Advanced Readline and History Functionality"><code class="filename">readline</code></a></span>);
and a <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>full</strong></span></a> <a href="impnotes.html#linkset" class="olink">linking set</a> with modules <span class="module"><a href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/clx/new-clx/"><code class="filename">clx/new-clx</code></a></span> and <span class="module"><a class="filename" href="#pcre" title="33.15. Perl Compatible Regular Expressions"><code class="filename">pcre</code></a></span> in addition
to the 3 (or 4) <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>base</strong></span></a> modules.</p><p>Here we list the included modules by their general theme.
 See <a class="xref" href="#ext-modules" title="Chapter 33. Extensions Implemented as Modules">Chapter 33, <em>Extensions Implemented as Modules</em></a> for individual module documentation.</p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="base-modules"></a>32.2.9.1. Base Modules</h4></div></div></div><p>The default build process includes the following modules
  in <span class="strong"><strong>both</strong></span> <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>base</strong></span></a> <span class="strong"><strong>and</strong></span> <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>full</strong></span></a> <a href="impnotes.html#linkset" class="olink">linking set</a>s:
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="module"><a class="filename" href="#i18n-mod" title="33.3. Internationalization of User Programs"><code class="filename">i18n</code></a></span></span></dt><dd>Internationalization of User Programs.
 </dd><dt><span class="term"><span class="module"><a class="filename" href="#regexp-mod" title="33.4. POSIX Regular Expressions"><code class="filename">regexp</code></a></span></span></dt><dd>The <a class="ulink" href="http://www.opengroup.org/austin/papers/posix_faq.html" target="_top"><span class="platform">POSIX</span></a> <a class="ulink" href="regexp.html" target="_top">Regular
     Expressions</a> matching, compiling, executing.
 </dd><dt><span class="term"><span class="module"><a class="filename" href="#syscalls" title="33.2. System Calls"><code class="filename">syscalls</code></a></span></span></dt><dd>Use some system calls in a platform-independent way.
 </dd><dt><span class="term"><span class="module"><a class="filename" href="#readline-mod" title="33.5. Advanced Readline and History Functionality"><code class="filename">readline</code></a></span> (only when <span class="strong"><strong>both</strong></span> <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://tiswww.case.edu/php/chet/readline/readline.html" target="_top">readline</a> and
    <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> are available)</span></dt><dd>Some advanced readline and history features are exported
  using this module.</dd></dl></div><p>The composition of the <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>full</strong></span></a> <a href="impnotes.html#linkset" class="olink">linking set</a> depends on the platform
  and on the vendor preferences.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="incmod-db"></a>32.2.9.2. Database, Directory et al</h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="module"><a class="filename" href="#gdbm" title="33.6. GDBM - The GNU database manager"><code class="filename">gdbm</code></a></span></span></dt><dd>Interface to <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/gdbm/" target="_top">DataBase Manager</a> by
    <span class="author"><span class="firstname">Masayuki</span> <span class="surname">Onjo</span></span>.
 </dd><dt><span class="term"><span class="module"><a class="filename" href="#berkeley-db" title="33.7. Berkeley DB access"><code class="filename">berkeley-db</code></a></span></span></dt><dd><a class="bdb" href="http://download.oracle.com/otndocs/products/berkeleydb/html/index.html">Berkeley DB</a>
    interface.</dd><dt><span class="term"><span class="module"><a class="filename" href="#dir-key" title="33.8. Directory Access"><code class="filename">dirkey</code></a></span></span></dt><dd>Directory Access (LDAP, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> registry etc).
 </dd><dt><span class="term"><span class="module"><a class="filename" href="#postgresql" title="33.9. PostgreSQL Database Access"><code class="filename">postgresql</code></a></span></span></dt><dd>Access <a class="ulink" href="http://www.PostgreSQL.org/" target="_top">PostgreSQL</a> from <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.
  </dd><dt><span class="term"><span class="module"><a class="filename" href="#oracle" title="33.10. Oracle Interface"><code class="filename">oracle</code></a></span></span></dt><dd>Access <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> RDBMS from <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>; by <span class="author"><span class="firstname">John</span> <span class="surname">Hinsdale</span></span>.
 </dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="incmod-kdml"></a>32.2.9.3. Mathematics, Data Mining et al</h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="module"><a class="filename" href="#libsvm" title="33.11. LibSVM Interface"><code class="filename">libsvm</code></a></span></span></dt><dd>Build
    <a class="ulink" href="http://www.support-vector-machines.org/" target="_top">Support
     Vector Machine</a> models using <a class="ulink" href="http://www.csie.ntu.edu.tw/~cjlin/libsvm/" target="_top">LibSVM</a> inside <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.
 </dd><dt><span class="term"><span class="module"><a class="filename" href="#pari" title="33.12. Computer Algebra System PARI"><code class="filename">pari</code></a></span></span></dt><dd>Interface to the computer algebra system <a class="ulink" href="http://pari.math.u-bordeaux.fr/" target="_top">PARI</a>.
 </dd><dt><span class="term"><span class="module"><a class="filename" href="#matlab" title="33.13. Matlab Interface"><code class="filename">matlab</code></a></span></span></dt><dd>Do matrix computations via
    <a class="ulink" href="http://www.mathworks.com/products/matlab/" target="_top">MATLAB</a>.
 </dd><dt><span class="term"><span class="module"><a class="filename" href="#netica" title="33.14. Netica Interface"><code class="filename">netica</code></a></span></span></dt><dd>Work with Bayesian belief networks and influence
    diagrams using <a class="ulink" href="http://norsys.com/netica_c_api.htm" target="_top">Netica C API</a>.</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="incmod-match"></a>32.2.9.4. Matching, File Processing et al</h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="module"><a class="filename" href="#pcre" title="33.15. Perl Compatible Regular Expressions"><code class="filename">pcre</code></a></span></span></dt><dd>The <a class="ulink" href="http://www.pcre.org/" target="_top">Perl Compatible Regular Expressions</a> matching, compiling, executing.
 </dd><dt><span class="term"><span class="module"><a class="filename" href="#zlib" title="33.16. Interface to zlib"><code class="filename">zlib</code></a></span></span></dt><dd>Compress <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a>s using <a class="ulink" href="http://zlib.net" target="_top">ZLIB</a>.
 </dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="incmod-net"></a>32.2.9.5. Communication, Networking</h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="module"><a class="filename" href="#rawsock" title="33.17. Raw Socket Access"><code class="filename">rawsock</code></a></span></span></dt><dd>Raw socket access.</dd><dt><span class="term"><span class="module"><a class="filename" href="#dbus" title="33.19. Interface to D-Bus"><code class="filename">dbus</code></a></span></span></dt><dd>Interface to <a class="ulink" href="http://www.freedesktop.org/wiki/Software/dbus" target="_top">D-Bus</a>.
</dd><dt><span class="term"><span class="module"><a class="filename" href="#fastcgi" title="33.18. The FastCGI Interface"><code class="filename">fastcgi</code></a></span></span></dt><dd>Access <a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a> from <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>;
    by <span class="author"><span class="firstname">John</span> <span class="surname">Hinsdale</span></span>.</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="incmod-gui"></a>32.2.9.6. Graphics</h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="ulink" href="http://www.cliki.net/CLX" target="_top"><span class="command"><strong>CLX</strong></span></a></span></dt><dd><p>Call
   <a class="ulink" href="http://www.x.org/docs/X11/xlib.pdf" target="_top">Xlib</a>
   functions from <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.  Two implementations are supplied:
  </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="module"><a href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/clx/mit-clx/"><code class="filename">clx/mit-clx</code></a></span>, from MIT
   <a class="ulink" href="https://www.x.org/archive/unsupported/lib/CLX/" target="_top">https://www.x.org/archive/unsupported/lib/CLX/</a></span></dt><dd>the standard implementation
  </dd><dt><span class="term"><span class="module"><a href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/clx/new-clx/"><code class="filename">clx/new-clx</code></a></span>, by <span class="author"><span class="firstname">Gilbert</span> <span class="surname">Baumann</span></span></span></dt><dd><p>faster, with additional features, but not quite complete yet.
    Please try it first and use <span class="module"><a href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/clx/mit-clx/"><code class="filename">clx/mit-clx</code></a></span> only
    if <span class="module"><a href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/clx/new-clx/"><code class="filename">clx/new-clx</code></a></span> does not work for you.
    <span class="module"><a href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/clx/new-clx/"><code class="filename">clx/new-clx</code></a></span> comes with several demos, please try them using
    </p><pre class="screen"><strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp.html#clisp" class="olink">clisp</a></strong></span> <code class="option"><a href="clisp.html#opt-link-set" class="olink">-K</a></code> <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>full</strong></span></a> <code class="option"><a href="clisp.html#opt-init" class="olink">-i</a></code> <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/clx/new-clx/demos/clx-demos.lisp"><code class="filename">modules/clx/new-clx/demos/clx-demos.lisp</code></a> <code class="option"><a href="clisp.html#opt-exec-expr" class="olink">-x</a></code> '(clx-demos:run-all-demos)'</pre><p>
     and follow the intructions.</p></dd></dl></div><p>This functionality is documented in the manual
  <a class="ulink" href="https://common-lisp.net/project/cmucl/doc/clx/" target="_top">https://common-lisp.net/project/cmucl/doc/clx/</a>, also
  available in the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> source distribution as
  <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/clx/clx-manual.tar.gz"><code class="filename">modules/clx/clx-manual.tar.gz</code></a>.
 </p></dd><dt><span class="term"><span class="module"><a class="filename" href="#gtk" title="33.20. GTK Interface"><code class="filename">gtk2</code></a></span></span></dt><dd>Use <a class="ulink" href="http://www.gtk.org" target="_top">GTK+</a> and <a class="ulink" href="http://glade.gnome.org/" target="_top">Glade</a> to create GUI by
    <span class="author"><span class="firstname">James</span> <span class="surname">Bailey</span></span>.
 </dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="incmod-bind"></a>32.2.9.7. Bindings</h4></div></div></div><p>Call the operating system functions from <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.
  The following platforms are supported:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="module"><a href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/bindings/glibc/"><code class="filename">bindings/glibc</code></a></span></span></dt><dd><a class="ulink" href="https://www.kernel.org/" target="_top"><span class="platform">Linux</span></a>/<a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/libc/" target="_top">libc</a></dd><dt><span class="term"><span class="module"><a href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/bindings/win32/"><code class="filename">bindings/win32</code></a></span></span></dt><dd><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="incmod-toys"></a>32.2.9.8. Toys and Games</h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="module"><a href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/queens/"><code class="filename">queens</code></a></span></span></dt><dd>Compute the number of solutions to the <em class="replaceable"><code>n</code></em>-queens
    problem on a <em class="replaceable"><code>n</code></em>×<em class="replaceable"><code>n</code></em> chessboard (a toy
    example for the users to explore the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a href="impnotes.html#modules" class="olink">module</a> system).
 </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/clx/new-clx/demos/sokoban.lisp"><code class="filename">modules/clx/new-clx/demos/sokoban.lisp</code></a></span></dt><dd>a demo which comes with <span class="module"><a href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/clx/new-clx/"><code class="filename">clx/new-clx</code></a></span>.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="incmod-misc"></a>32.2.9.9. Miscellaneous</h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="module"><a class="filename" href="#asdf" title="33.1. A System Definition Facility"><code class="filename">asdf</code></a></span></span></dt><dd>A system definition facility.
 </dd></dl></div></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="dffi"></a>32.3. The Foreign Function Call Facility</h2></div><div><h3 class="subtitle"><span class="plat-dep">Platform Dependent: <span class="plat-dep">Many <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platforms
  only.</span></span></h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#dffi-intro">32.3.1. Introduction</a></span></dt><dt><span class="section"><a href="#dffi-overview">32.3.2. Overview</a></span></dt><dt><span class="section"><a href="#dffi-types">32.3.3. (Foreign) <span class="command"><strong>C</strong></span> types</a></span></dt><dt><span class="section"><a href="#c-flavor">32.3.4. The choice of the <span class="command"><strong>C</strong></span> flavor</a></span></dt><dt><span class="section"><a href="#dffi-variables">32.3.5. Foreign variables</a></span></dt><dt><span class="section"><a href="#dffi-places">32.3.6. Operations on foreign places</a></span></dt><dt><span class="section"><a href="#dffi-functions">32.3.7. Foreign functions</a></span></dt><dd><dl><dt><span class="section"><a href="#dffi-callback-mem">32.3.7.1. Callbacks and memory management</a></span></dt></dl></dd><dt><span class="section"><a href="#allocation">32.3.8. Argument and result passing conventions</a></span></dt><dt><span class="section"><a href="#param-mode">32.3.9. Parameter Mode</a></span></dt><dt><span class="section"><a href="#dffi-examples">32.3.10. Examples</a></span></dt><dd><dl><dt><span class="section"><a href="#dffi-ex-more">32.3.10.1. More examples</a></span></dt></dl></dd></dl></div><div class="list-of-examples"><p><strong>List of Examples</strong></p><dl><dt>32.2. <a href="#dffi-simple">Simple declarations and access</a></dt><dt>32.3. <a href="#dffi-extern-var">External <span class="command"><strong>C</strong></span> variable and some accesses</a></dt><dt>32.4. <a href="#dffi-extern-func1">Calling an external function</a></dt><dt>32.5. <a href="#dffi-extern-func2">Another example for calling an external function</a></dt><dt>32.6. <a href="#dffi-ex-macro">Accessing <span class="command"><strong>cpp</strong></span> macros</a></dt><dt>32.7. <a href="#ex-call-in">Calling Lisp from <span class="command"><strong>C</strong></span></a></dt><dt>32.8. <a href="#ex-call-in-dll">Calling Lisp from <span class="command"><strong>C</strong></span> dynamically</a></dt><dt>32.9. <a href="#dffi-gethostname">Variable size arguments:   calling <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/gethostname.html"><code class="function">gethostname</code></a> from <span class="command"><strong>CLISP</strong></span></a></dt><dt>32.10. <a href="#dffi-dll-var">Accessing variables in shared libraries</a></dt><dt>32.11. <a href="#ex-dffi-validity">Controlling validity of resources</a></dt><dt>32.12. <a href="#ex-dffi-float">Floating point arrays</a></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="dffi-intro"></a>32.3.1. Introduction</h3></div></div></div><p>This facility, also known as <span class="quote">“<span class="quote">Foreign Language Interface</span>”</span>,
allows one to call a function implemented in <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> from inside <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
and to do many related things, like inspect and modify foreign memory,
define a <span class="quote">“<span class="quote">callback</span>”</span> (i.e., make a lisp function available
to the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> world), etc.
To use this facility, one writes a <strong class="first"><em class="firstterm">foreign function
  <a id="dffi-ff" class="indexterm"></a></em></strong> description into an
ordinary Lisp file, which is then compiled and loaded as usual;
or just evaluates the appropriate form in the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-1.html">read-eval-print loop</a>.</p><p>There are two basic ways to do define a foreign function:</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p class="simpara">Use <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/dlopen.html"><code class="function">dlopen</code></a> and <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/dlsym.html"><code class="function">dlsym</code></a> to get to the location of the
  function code in a dynamic library.
  To access this facility, pass the <code class="constant">:LIBRARY</code> option to <a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a>
  and <a class="link" href="#def-c-var"><code class="function">FFI:DEF-C-VAR</code></a>.</p><p class="simpara">Unfortunately, this functionality is not available on some
  operating systems, and, also, it offers only a part of the foreign
  functionality: <a class="ulink" href="http://gcc.gnu.org/onlinedocs/cpp/" target="_top"><span class="command"><strong>cpp</strong></span></a> macros and <code class="literal">inline</code> functions
  cannot be accessed this way.  On the other hand, this functionality
  is available in the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-1.html">read-eval-print loop</a> and does not require a <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> compiler.
</p></li><li class="listitem">Use a somewhat less direct way: when you do not use
  the <code class="constant">:LIBRARY</code> argument, <a href="impnotes.html#compilefile" class="olink"><code class="function">COMPILE-FILE</code></a> produces a <code class="filename">#P".c"</code> file
  (in addition to a <code class="filename">#P".fas"</code> and a <a class="link" href="#lib-files" title="24.3.4. Interaction with COMPILE-FILE"><code class="filename">#P".lib"</code></a>).
  Then you compile (with a <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> compiler) and link it into <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
  (statically, linking it into <code class="filename">lisp.a</code>, or
  dynamically, loading it into a running <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> using <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/dlopen.html"><code class="function">dlopen</code></a> and <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/dlsym.html"><code class="function">dlsym</code></a>).
  This way you can use any functionality your foreign library exports,
  whether using ordinary functions, <code class="literal">inline</code> functions,
  or <a class="ulink" href="http://gcc.gnu.org/onlinedocs/cpp/" target="_top"><span class="command"><strong>cpp</strong></span></a> macros (see <a class="xref" href="#dffi-ex-macro" title="Example 32.6. Accessing cpp macros">Example 32.6, “Accessing <span class="command"><strong>cpp</strong></span> macros”</a>).
 </li></ol></div><p>
</p><p>All symbols relating to the foreign function interface are
 exported from the package <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>.
 To use them, <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_use-package.html" target="_top"><code class="function">USE-PACKAGE</code></a> <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>)</code>.</p><p>Special <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> forms may appear anywhere in the Lisp file.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="dffi-overview"></a>32.3.2. Overview</h3></div></div></div><p>These are the special <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> forms.  We have taken a pragmatic
 approach: the only foreign languages we support for now are <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>
 and <a class="ulink" href="http://www.ansi.org/" target="_top"><acronym class="acronym" title="The American National Standards Institute">ANSI</acronym></a> <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>Unless specifically noted otherwise, type specification
  parameters are <span class="strong"><strong>not</strong></span> evaluated, so that they can be compiled by
  <a class="link" href="#c-type-parse"><code class="function">FFI:PARSE-C-TYPE</code></a> into the internal format at macroexpansion time.
</p></div><div class="variablelist"><p class="title"><strong>High-level <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> forms; <em class="replaceable"><code>name</code></em> is any Lisp
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>; <em class="replaceable"><code>c-name</code></em> is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a></strong></p><dl class="variablelist"><dt><a id="def-c-type"></a><span class="term"><code class="code">(<a class="link" href="#def-c-type"><code class="function">FFI:DEF-C-TYPE</code></a> <em class="replaceable"><code>name</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>c-type</code></em>)</code></span></dt><dd><p class="simpara">This form makes <em class="replaceable"><code>name</code></em> a shortcut for <em class="replaceable"><code>c-type</code></em>.
   Note that <em class="replaceable"><code>c-type</code></em> may already refer to <em class="replaceable"><code>name</code></em>.
   Forward declarations of types are not possible, however.</p><p class="simpara">When <em class="replaceable"><code>c-type</code></em> is omitted, the type is assumed to be an
   integer, and its size and signedness are determined at link time,
   e.g., <code class="code">(<a class="link" href="#def-c-type"><code class="function">FFI:DEF-C-TYPE</code></a> size_t)</code>.</p></dd><dt><a id="def-c-var"></a><span class="term"><code class="code">(<a class="link" href="#def-c-var"><code class="function">FFI:DEF-C-VAR</code></a> <em class="replaceable"><code>name</code></em>
   {<em class="replaceable"><code>option</code></em>}*)</code></span></dt><dd><p class="simpara">This form defines a <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a>.
  <em class="replaceable"><code>name</code></em> is the Lisp name, a regular Lisp <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>.</p><div class="variablelist"><a id="def-c-var-opts"></a><p class="title"><strong>Options for <a class="link" href="#def-c-var"><code class="function">FFI:DEF-C-VAR</code></a></strong></p><dl class="variablelist"><dt><span class="term"><code class="code">(<code class="constant">:NAME</code> <em class="replaceable"><code>c-name</code></em>)</code></span></dt><dd>specifies the name as seen from <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>, as a
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>.  If not specified, it is derived from the print name of
   the Lisp name.</dd><dt><span class="term"><code class="code">(<code class="constant">:TYPE</code> <em class="replaceable"><code>c-type</code></em>)</code></span></dt><dd>specifies the variable's foreign type.
</dd><dt><span class="term"><code class="code">(<code class="constant">:READ-ONLY</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_boolean.html" target="_top"><code class="classname">BOOLEAN</code></a>)</code></span></dt><dd>If this option is specified and non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>,
   it will be impossible to change the variable's value from within
   Lisp (using <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/spefor_setq.html" target="_top"><code class="function">SETQ</code></a> or similar).</dd><dt><span class="term"><code class="code">(:ALLOC <a class="link" href="#allocation" title="32.3.8. Argument and result passing conventions"><em class="replaceable"><code>ALLOCATION</code></em></a>)</code></span></dt><dd>This option can be either <code class="constant">:NONE</code> or
   <code class="constant">:MALLOC-FREE</code> and defaults to <code class="constant">:NONE</code>.
   If it is <code class="constant">:MALLOC-FREE</code>, any values of type <a class="link" href="#c-string"><span class="type">FFI:C-STRING</span></a>, <a class="link" href="#c-ptr"><span class="type">FFI:C-PTR</span></a>,
   <a class="link" href="#c-ptr-null"><span class="type">FFI:C-PTR-NULL</span></a>, <a class="link" href="#c-array-ptr"><span class="type">FFI:C-ARRAY-PTR</span></a> within the foreign value are assumed
   to be pointers to <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/malloc.html"><code class="function">malloc</code></a>-allocated storage, and when <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/spefor_setq.html" target="_top"><code class="function">SETQ</code></a>
   replaces an old value by a new one, the old storage is freed using
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/free.html"><code class="function">free</code></a> and the new storage allocated using <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/malloc.html"><code class="function">malloc</code></a>.
   If it is <code class="constant">:NONE</code>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/spefor_setq.html" target="_top"><code class="function">SETQ</code></a> assumes that the pointers point to good
   storage (not <code class="constant">NULL</code>!) and overwrites the old values by the new ones.
   This is dangerous (just think of overwriting a string with a longer
   one or storing some data in a <code class="constant">NULL</code> pointer...) and deprecated.
</dd><dt><span class="term"><code class="code">(<code class="constant">:LIBRARY</code> <em class="replaceable"><code>name</code></em>)</code></span></dt><dd>Specifies the (optional) dynamic library
   which contains the variable, the default is set by
   <a class="link" href="#dffi-default-lib"><code class="function">FFI:DEFAULT-FOREIGN-LIBRARY</code></a>.</dd><dt><span class="term"><code class="code">(<code class="constant">:VERSION</code> <em class="replaceable"><code>version</code></em>)</code></span></dt><dd>Specifies the (optional) symbol version in the library
   (therefore, if <code class="constant">:VERSION</code> is supplied, <code class="constant">:LIBRARY</code> must also be supplied)
</dd><dt><span class="term"><code class="code">(<code class="constant">:DOCUMENTATION</code> <em class="replaceable"><code>string</code></em>)</code></span></dt><dd>Specifies the (optional) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_doc_umentationcp.html" target="_top"><code class="function">VARIABLE</code></a> documentation.
</dd></dl></div></dd><dt><a id="def-c-const"></a><span class="term"><code class="code">(<a class="link" href="#def-c-const"><code class="function">FFI:DEF-C-CONST</code></a> <em class="replaceable"><code>name</code></em>
   {<em class="replaceable"><code>option</code></em>}*)</code></span></dt><dd><p>This form defines a Lisp <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-1-3.html">constant variable</a> <em class="replaceable"><code>name</code></em> whose value is
   determined at build time using an internal <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a>.</p><div class="variablelist"><a id="def-c-const-opts"></a><p class="title"><strong>Options for <a class="link" href="#def-c-const"><code class="function">FFI:DEF-C-CONST</code></a></strong></p><dl class="variablelist"><dt><span class="term"><code class="code">(<code class="constant">:NAME</code> <em class="replaceable"><code>c-name</code></em>)</code></span></dt><dd>specifies the name as seen from <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>, as a
      <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>.  If not specified, it is derived from the print name
      of the Lisp name.</dd><dt><span class="term"><code class="code">(<code class="constant">:TYPE</code> <em class="replaceable"><code>c-type</code></em>)</code></span></dt><dd><p>specifies the constant's foreign type, one of
      </p><table border="0" summary="Simple list" class="simplelist"><tr><td><span class="type">FFI:INT</span></td></tr><tr><td><a class="link" href="#c-string"><span class="type">FFI:C-STRING</span></a></td></tr><tr><td><a class="link" href="#c-pointer"><span class="type">FFI:C-POINTER</span></a></td></tr></table></dd><dt><span class="term"><code class="code">(<code class="constant">:GUARD</code>
      <em class="replaceable"><code>string</code></em>)</code></span></dt><dd><p>specifies the <a class="ulink" href="http://gcc.gnu.org/onlinedocs/cpp/" target="_top"><span class="command"><strong>cpp</strong></span></a> check to wrap around <em class="replaceable"><code>c-name</code></em>,
      defaults to <span class="data"><code class="literal">"defined(<em class="replaceable"><code>c-name</code></em>)"</code></span>;
      can be <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> to omit the test. When the test fails, <em class="replaceable"><code>name</code></em> is
      unbound.</p></dd><dt><span class="term"><code class="code">(<code class="constant">:DOCUMENTATION</code> <em class="replaceable"><code>string</code></em>)</code></span></dt><dd>Specifies the (optional) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_doc_umentationcp.html" target="_top"><code class="function">VARIABLE</code></a> documentation.
  </dd></dl></div><p class="simpara">See also <a class="xref" href="#dffi-ex-macro" title="Example 32.6. Accessing cpp macros">Example 32.6, “Accessing <span class="command"><strong>cpp</strong></span> macros”</a>.</p></dd><dt><a id="def-call-out"></a><span class="term"><code class="code">(<a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a>
              <em class="replaceable"><code>name</code></em> {<em class="replaceable"><code>option</code></em>}*)</code></span></dt><dd><p class="simpara">This form defines a named call-out function (a
 foreign function called from Lisp: control flow temporarily leaves Lisp).
 </p><div class="variablelist"><a id="def-call-out-opts"></a><p class="title"><strong>Options for <a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a></strong></p><dl class="variablelist"><dt><span class="term"><code class="code">(<code class="constant">:NAME</code> <em class="replaceable"><code>c-name</code></em>)</code></span></dt><dd>Any Lisp function call to <code class="function">#'<em class="replaceable"><code>name</code></em></code>
  is redirected to call the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> function <em class="replaceable"><code>c-name</code></em>.
</dd><dt><span class="term"><code class="code">(<code class="constant">:ARGUMENTS</code>
   {(<em class="replaceable"><code>argument</code></em> <em class="replaceable"><code>c-type</code></em> [<a class="link" href="#param-mode" title="32.3.9. Parameter Mode"><em class="replaceable"><code>PARAM-MODE</code></em></a> [<a class="link" href="#allocation" title="32.3.8. Argument and result passing conventions"><em class="replaceable"><code>ALLOCATION</code></em></a>]])}*)</code><br /></span><span class="term"><code class="code">(<code class="constant">:RETURN-TYPE</code> <em class="replaceable"><code>c-type</code></em> [<a class="link" href="#allocation" title="32.3.8. Argument and result passing conventions"><em class="replaceable"><code>ALLOCATION</code></em></a>])</code></span></dt><dd>Argument list and return value, see
   <a class="xref" href="#allocation" title="32.3.8. Argument and result passing conventions">Section 32.3.8, “Argument and result passing conventions”</a> and <a class="xref" href="#param-mode" title="32.3.9. Parameter Mode">Section 32.3.9, “Parameter Mode”</a>.
</dd><dt><span class="term"><code class="code">(<a class="link" href="#c-flavor" title="32.3.4. The choice of the C flavor"><code class="constant">:LANGUAGE</code></a> <em class="replaceable"><code>language</code></em>)</code></span></dt><dd>See <a class="xref" href="#c-flavor" title="32.3.4. The choice of the C flavor">Section 32.3.4, “The choice of the <span class="command"><strong>C</strong></span> flavor”</a>.
</dd><dt><span class="term"><code class="code">(:BUILT-IN <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_boolean.html" target="_top"><code class="classname">BOOLEAN</code></a>)</code></span></dt><dd>When the function is a <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> built-in, the full
   prototype will be output (unless suppressed by <a class="link" href="#ffi-extern-output"><code class="varname">FFI:*OUTPUT-C-FUNCTIONS*</code></a>).
</dd><dt><span class="term"><code class="code">(<code class="constant">:LIBRARY</code> <em class="replaceable"><code>name</code></em>)</code></span></dt><dd>Specifies the (optional) dynamic library
   which contains the function, the default is set by
   <a class="link" href="#dffi-default-lib"><code class="function">FFI:DEFAULT-FOREIGN-LIBRARY</code></a>.</dd><dt><span class="term"><code class="code">(<code class="constant">:VERSION</code> <em class="replaceable"><code>version</code></em>)</code></span></dt><dd>Specifies the (optional) symbol version in the library
   (therefore, if <code class="constant">:VERSION</code> is supplied, <code class="constant">:LIBRARY</code> must also be supplied).
</dd><dt><span class="term"><code class="code">(<code class="constant">:DOCUMENTATION</code> <em class="replaceable"><code>string</code></em>)</code></span></dt><dd>Specifies the (optional) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_doc_umentationcp.html" target="_top"><code class="function">FUNCTION</code></a> documentation.
</dd></dl></div><p class="simpara">See also <a class="xref" href="#dffi-functions" title="32.3.7. Foreign functions">Section 32.3.7, “Foreign functions”</a>.</p></dd><dt><a id="def-call-in"></a><span class="term"><code class="code">(<a class="link" href="#def-call-in"><code class="function">FFI:DEF-CALL-IN</code></a>
   <em class="replaceable"><code>function</code></em> {<em class="replaceable"><code>option</code></em>}*)</code></span></dt><dd><p class="simpara">This form defines a
  <strong class="first"><em class="firstterm">callback<a id="def-call-in-callback" class="indexterm"></a></em></strong> -
  a named call-in function (i.e., a Lisp function called from the
  foreign language: control flow temporary enters Lisp)</p><div class="variablelist"><a id="def-call-in-opts"></a><p class="title"><strong>Options for <a class="link" href="#def-call-in"><code class="function">FFI:DEF-CALL-IN</code></a></strong></p><dl class="variablelist"><dt><span class="term"><code class="code">(<code class="constant">:NAME</code> <em class="replaceable"><code>c-name</code></em>)</code></span></dt><dd>Any <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> function call to the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> function
   <em class="replaceable"><code>c-name</code></em> is redirected to call the <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> function <em class="replaceable"><code>function</code></em>, which
   should be a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_f.html#function_name">function name</a>.</dd><dt><span class="term"><code class="code">(<code class="constant">:ARGUMENTS</code>
   {(<em class="replaceable"><code>argument</code></em> <em class="replaceable"><code>c-type</code></em> [<a class="link" href="#param-mode" title="32.3.9. Parameter Mode"><em class="replaceable"><code>PARAM-MODE</code></em></a> [<a class="link" href="#allocation" title="32.3.8. Argument and result passing conventions"><em class="replaceable"><code>ALLOCATION</code></em></a>]])}*)</code><br /></span><span class="term"><code class="code">(<code class="constant">:RETURN-TYPE</code> <em class="replaceable"><code>c-type</code></em> [<a class="link" href="#allocation" title="32.3.8. Argument and result passing conventions"><em class="replaceable"><code>ALLOCATION</code></em></a>])</code></span></dt><dd>Argument list and return value, see
   <a class="xref" href="#allocation" title="32.3.8. Argument and result passing conventions">Section 32.3.8, “Argument and result passing conventions”</a> and <a class="xref" href="#param-mode" title="32.3.9. Parameter Mode">Section 32.3.9, “Parameter Mode”</a>.
</dd><dt><span class="term"><code class="code">(<a class="link" href="#c-flavor" title="32.3.4. The choice of the C flavor"><code class="constant">:LANGUAGE</code></a> <em class="replaceable"><code>language</code></em>)</code></span></dt><dd>See <a class="xref" href="#c-flavor" title="32.3.4. The choice of the C flavor">Section 32.3.4, “The choice of the <span class="command"><strong>C</strong></span> flavor”</a>.
</dd></dl></div><p class="simpara">See also <a class="xref" href="#dffi-functions" title="32.3.7. Foreign functions">Section 32.3.7, “Foreign functions”</a>.</p></dd><dt><a id="dffi-open-lib"></a><span class="term"><code class="code">(<a class="link" href="#dffi-open-lib"><code class="function">FFI:OPEN-FOREIGN-LIBRARY</code></a>
   <em class="replaceable"><code>name</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :REQUIRE)</code></span></dt><dd><p class="simpara">Open (load) a shared foreign library.</p><p class="simpara">Some shared libraries depend on other shared libraries
   and this dependency can be specified using
   the <code class="constant">:REQUIRE</code> argument.</p><p class="simpara">Unless the library has dependencies, this is only needed if
   you want to test for <span class="emphasis"><em>presence</em></span> of a library
   without creating a foreign object referencing its contents.
   When you create a <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a> or a <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a>
   using <a class="link" href="#def-c-var"><code class="function">FFI:DEF-C-VAR</code></a> or <a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> with a <code class="constant">:LIBRARY</code> argument,
   the library <em class="replaceable"><code>name</code></em> is opened automatically.</p><p>E.g., <code class="filename">libgsl.so</code>
  requires <code class="filename">libgslcblas.so</code>:</p><pre class="programlisting">
(<a class="link" href="#dffi-open-lib"><code class="function">FFI:OPEN-FOREIGN-LIBRARY</code></a> "libgsl.so")
*** - FFI:OPEN-FOREIGN-LIBRARY: Cannot open library "libgsl.so": "/usr/lib64/libgsl.so: undefined symbol: cblas_ctrmv"
</pre><p> so a common way is to pre-open the dependency:
</p><pre class="programlisting">
(<a class="link" href="#dffi-open-lib"><code class="function">FFI:OPEN-FOREIGN-LIBRARY</code></a> "libgslcblas.so")
(<a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> gsl_cheb_alloc (<code class="constant">:LIBRARY</code> "libgsl.so") (:language :stdc)
  (:arguments (n ffi:int)) (:return-type ffi:c-pointer))
⇒ <code class="computeroutput">GSL_CHEB_ALLOC</code>
</pre><p> Alas, this would work <span class="emphasis"><em>in the current
 image</em></span> only: if you save the
 image, <code class="function">GSL_CHEB_ALLOC</code> will <span class="strong"><strong>not</strong></span> work there
 because <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> will try to re-open <code class="filename">libgsl.so</code> and
 fail as above.  However, using the <code class="constant">:REQUIRE</code> argument
 will tell <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> to re-open <span class="strong"><strong>both</strong></span> libraries in the right order:</p><pre class="screen">
<strong><code class="prompt">$</code></strong> clisp
&gt; (<a class="link" href="#dffi-open-lib"><code class="function">FFI:OPEN-FOREIGN-LIBRARY</code></a> "libgsl.so" :require '("libgslcblas.so"))
&gt; (<a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> gsl_cheb_alloc (:library "libgsl.so") (:language :stdc)
  (:arguments (n ffi:int)) (:return-type ffi:c-pointer))
&gt; (<a href="impnotes.html#image" class="olink"><code class="function">EXT:SAVEINITMEM</code></a> "foo" :executable t)
&gt; (<a class="link" href="#quit" title="31.3. Quitting CLISP"><code class="function">EXT:EXIT</code></a>)
<strong><code class="prompt">$</code></strong> ./foo
&gt; (gsl_cheb_alloc 10)
<code class="computeroutput">#&lt;<a class="link" href="#faddr"><code class="classname">FFI:FOREIGN-ADDRESS</code></a> #x0000000017AC38A0&gt;</code>
</pre></dd><dt><a id="dffi-close-lib"></a><span class="term"><code class="code">(<a class="link" href="#dffi-close-lib"><code class="function">FFI:CLOSE-FOREIGN-LIBRARY</code></a>
   <em class="replaceable"><code>name</code></em>)</code></span></dt><dd><p class="simpara">Close (unload) a shared foreign library (opened by
   <a class="link" href="#dffi-open-lib"><code class="function">FFI:OPEN-FOREIGN-LIBRARY</code></a> or the <code class="constant">:LIBRARY</code> argument to <a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a>
   or <a class="link" href="#def-c-var"><code class="function">FFI:DEF-C-VAR</code></a>).</p><p class="simpara">If you want to modify your shared library, you need to close
   it using <a class="link" href="#dffi-close-lib"><code class="function">FFI:CLOSE-FOREIGN-LIBRARY</code></a> first.  When you use a
   <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a> or a <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a> which resides in the
   library <em class="replaceable"><code>name</code></em>, it will be re-opened automatically.
</p></dd><dt><a id="dffi-default-lib"></a><span class="term"><code class="code">(<a class="link" href="#dffi-default-lib"><code class="function">FFI:DEFAULT-FOREIGN-LIBRARY</code></a>
   <em class="replaceable"><code>library-name</code></em>)</code></span></dt><dd><p class="simpara">This macro sets the default <code class="constant">:LIBRARY</code> argument for
   <a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> and <a class="link" href="#def-c-var"><code class="function">FFI:DEF-C-VAR</code></a>.  <em class="replaceable"><code>library-name</code></em> should be <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
   (meaning use the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> file produced by <a href="impnotes.html#compilefile" class="olink"><code class="function">COMPILE-FILE</code></a>), a
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>, or, depending on the underlying <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/dlsym.html"><code class="function">dlsym</code></a>
   or <a class="bsd" href="http://www.freebsd.org/cgi/man.cgi?query=dlvsym"><code class="function">dlvsym</code></a> implementation,
   <code class="constant">:DEFAULT</code> or <code class="constant">:NEXT</code>.</p><p class="simpara">The default is set separately in each <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#compilation_unit">compilation unit</a>, so, if you
   are interfacing to a single library, you can set this variable in the
   beginning of your lisp file and omit the <code class="constant">:LIBRARY</code> argument
   throughout the file.</p></dd><dt><a id="def-c-struct"></a><span class="term"><code class="code">(<a class="link" href="#def-c-struct"><code class="function">FFI:DEF-C-STRUCT</code></a>
   <em class="replaceable"><code>name</code></em> (<em class="replaceable"><code>symbol</code></em> <em class="replaceable"><code>c-type</code></em>)*)</code></span></dt><dd><p>This form defines <em class="replaceable"><code>name</code></em> to be both a
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_structure-class.html" target="_top"><code class="classname">STRUCTURE-CLASS</code></a> and a foreign <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> type with the given slots.
  If this class representation overhead is not needed one should consider
  writing <code class="code">(<a class="link" href="#def-c-type"><code class="function">FFI:DEF-C-TYPE</code></a> <em class="replaceable"><code>name</code></em> (<a class="link" href="#c-struct"><span class="type">FFI:C-STRUCT</span></a>
  {<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> | <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a>} (<em class="replaceable"><code>symbol</code></em> <em class="replaceable"><code>c-type</code></em>)*))</code> instead.
  <em class="replaceable"><code>name</code></em> is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a> (structure name) or a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> whose <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_firstcm_s_inthcm_tenth.html" target="_top"><code class="function">FIRST</code></a>
  element is the structure name and the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_rest.html" target="_top"><code class="function">REST</code></a> is options.
  Two options are supported at this time:
  </p><div class="variablelist"><a id="def-c-struct-opts"></a><p class="title"><strong>Options for <a class="link" href="#def-c-struct"><code class="function">FFI:DEF-C-STRUCT</code></a></strong></p><dl class="variablelist"><dt><a id="def-c-struct-typedef"></a><span class="term"><code class="constant">:TYPEDEF</code></span></dt><dd>means that the name of this structure is a
      <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> type defined with <code class="function">typedef</code>
      elsewhere.</dd><dt><a id="def-c-struct-external"></a><span class="term"><code class="constant">:EXTERNAL</code></span></dt><dd>means that this structure is defined in a
      <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> header file that you include with, e.g.,
      <code class="code">(<a class="link" href="#c-lines"><code class="function">FFI:C-LINES</code></a> "#include &lt;filename.h&gt;~%")</code>.
  </dd></dl></div><p>
  These options determine how the struct is written to the <code class="filename">#P".c"</code>.
</p></dd><dt><a id="def-c-enum"></a><span class="term"><code class="code">(<a class="link" href="#def-c-enum"><code class="function">FFI:DEF-C-ENUM</code></a>
   <em class="replaceable"><code>name</code></em> {<em class="replaceable"><code>symbol</code></em> | (<em class="replaceable"><code>symbol</code></em> [<em class="replaceable"><code>value</code></em>])}*)</code></span></dt><dd><p class="simpara">This form defines <em class="replaceable"><code>symbol</code></em>s
  as constants, similarly to the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> declaration <span class="type">enum {
  <em class="replaceable"><code>symbol</code></em> [= <em class="replaceable"><code>value</code></em>], ... };</span></p><p class="simpara">You can use <code class="code">(<code class="function">FFI:ENUM-FROM-VALUE</code>
  <em class="replaceable"><code>name</code></em> <em class="replaceable"><code>value</code></em>)</code> and
 <code class="code">(<code class="function">FFI:ENUM-TO-VALUE</code> <em class="replaceable"><code>name</code></em>
  <em class="replaceable"><code>symbol</code></em>)</code> to convert between the numeric and symbolic
 representations (of course, the latter function boils down to
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_symbol-value.html" target="_top"><code class="function">SYMBOL-VALUE</code></a> plus a check that the <em class="replaceable"><code>symbol</code></em> is indeed a constant
 defined in the <a class="link" href="#def-c-enum"><code class="function">FFI:DEF-C-ENUM</code></a> <em class="replaceable"><code>name</code></em>).</p></dd><dt><a id="c-lines"></a><span class="term"><code class="code">(<a class="link" href="#c-lines"><code class="function">FFI:C-LINES</code></a> <em class="replaceable"><code>format-string</code></em>
   {<em class="replaceable"><code>argument</code></em>}*)</code></span></dt><dd><p class="simpara">This form outputs the string
   <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> <em class="replaceable"><code>format-string</code></em> {<em class="replaceable"><code>argument</code></em>}*)</code>
   to the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> output file's top level.
   This is usually used to include the relevant header files,
   see <a class="xref" href="#def-c-struct-external"><code class="constant">:EXTERNAL</code></a>
   and <a class="xref" href="#ffi-extern-output"><code class="varname">FFI:*OUTPUT-C-FUNCTIONS*</code></a>.</p><p>When <em class="replaceable"><code>format-string</code></em> is not a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>, is should be a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>,
   and then the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> {<em class="replaceable"><code>argument</code></em>}*)</code>
   is added to the appropriate <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> function:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:INIT-ALWAYS</code><br /></span><span class="term"><code class="constant">:INIT-ONCE</code></span></dt><dd><a class="link" href="#modinit" title="32.2.2. Module initialization">initialization
        function</a></dd><dt><span class="term"><code class="constant">:FINI</code></span></dt><dd><a class="link" href="#modfini" title="32.2.3. Module finalization">finalization
        function</a></dd></dl></div></dd><dt><a id="element"></a><span class="term"><code class="code">(<a class="link" href="#element"><code class="function">FFI:ELEMENT</code></a> <em class="replaceable"><code>c-place</code></em> <em class="replaceable"><code>index<sub>1</sub></code></em>
     ... <em class="replaceable"><code>index<sub>n</sub></code></em>)</code></span></dt><dd>Array element: If <em class="replaceable"><code>c-place</code></em> is of foreign type
   <span class="type"><code class="literal">(<a class="link" href="#c-array"><span class="type">FFI:C-ARRAY</span></a> <em class="replaceable"><code>c-type</code></em> (<em class="replaceable"><code>dim<sub>1</sub></code></em> ... <em class="replaceable"><code>dim<sub>n</sub></code></em>))</code></span>
   and 0 ≤ <em class="replaceable"><code>index<sub>1</sub></code></em> &lt; <em class="replaceable"><code>dim<sub>1</sub></code></em>, ..., 0 ≤ <em class="replaceable"><code>index<sub>n</sub></code></em> &lt; <em class="replaceable"><code>dim<sub>n</sub></code></em>,
   this will be the <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a> corresponding to <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_aref.html" target="_top"><code class="function">AREF</code></a> <em class="replaceable"><code>c-place</code></em>
   <em class="replaceable"><code>index<sub>1</sub></code></em> ... <em class="replaceable"><code>index<sub>n</sub></code></em>)</code> or
   <code class="varname"><em class="replaceable"><code>c-place</code></em>[<em class="replaceable"><code>index<sub>1</sub></code></em>]...[<em class="replaceable"><code>index<sub>n</sub></code></em>]</code>.
   It is a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a> of type <em class="replaceable"><code>c-type</code></em>.
   If <em class="replaceable"><code>c-place</code></em> is of foreign type <span class="type"><code class="literal">(<a class="link" href="#c-array-max"><span class="type">FFI:C-ARRAY-MAX</span></a>
    <em class="replaceable"><code>c-type</code></em> <em class="replaceable"><code>dim</code></em>)</code></span> and 0 ≤ <em class="replaceable"><code>index</code></em> &lt; <em class="replaceable"><code>dim</code></em>,
   this will be the <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a> corresponding to <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_aref.html" target="_top"><code class="function">AREF</code></a> <em class="replaceable"><code>c-place</code></em>
    <em class="replaceable"><code>index</code></em>)</code> or <code class="varname"><em class="replaceable"><code>c-place</code></em>[<em class="replaceable"><code>index</code></em>]</code>.
   It is a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a> of type <em class="replaceable"><code>c-type</code></em>.
</dd><dt><a id="deref"></a><span class="term"><code class="code">(<a class="link" href="#deref"><code class="function">FFI:DEREF</code></a> <em class="replaceable"><code>c-place</code></em>)</code></span></dt><dd>Dereference pointer: If
  <em class="replaceable"><code>c-place</code></em> is of foreign type
  <span class="type"><code class="literal">(<a class="link" href="#c-ptr"><span class="type">FFI:C-PTR</span></a> <em class="replaceable"><code>c-type</code></em>)</code></span>,
  <span class="type"><code class="literal">(<a class="link" href="#c-ptr-null"><span class="type">FFI:C-PTR-NULL</span></a> <em class="replaceable"><code>c-type</code></em>)</code></span> or
  <span class="type"><code class="literal">(<a class="link" href="#c-pointer"><span class="type">FFI:C-POINTER</span></a> <em class="replaceable"><code>c-type</code></em>)</code></span>,
  this will be the <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a> the pointer points to.
  It is a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a> of type <em class="replaceable"><code>c-type</code></em>.
  For <span class="type"><code class="literal">(<a class="link" href="#c-ptr-null"><span class="type">FFI:C-PTR-NULL</span></a> <em class="replaceable"><code>c-type</code></em>)</code></span>,
  the <em class="replaceable"><code>c-place</code></em> may not be <code class="constant">NULL</code>.
</dd><dt><a id="slot"></a><span class="term"><code class="code">(<a class="link" href="#slot"><code class="function">FFI:SLOT</code></a> <em class="replaceable"><code>c-place</code></em>
   <em class="replaceable"><code>slot-name</code></em>)</code></span></dt><dd>Struct or union component: If <em class="replaceable"><code>c-place</code></em> is of
   foreign type <span class="type"><code class="literal">(<a class="link" href="#c-struct"><span class="type">FFI:C-STRUCT</span></a> <em class="replaceable"><code>class</code></em> ...
    (<em class="replaceable"><code>slot-name</code></em> <em class="replaceable"><code>c-type</code></em>) ...)</code></span> or of
   type <span class="type"><code class="literal">(<a class="link" href="#c-union"><span class="type">FFI:C-UNION</span></a>
    ... (<em class="replaceable"><code>slot-name</code></em> <em class="replaceable"><code>c-type</code></em>) ...)</code></span>,
   this will be of type <em class="replaceable"><code>c-type</code></em>.</dd><dt><a id="cast"></a><span class="term"><code class="code">(<a class="link" href="#cast"><code class="function">FFI:CAST</code></a>
           <em class="replaceable"><code>c-place</code></em> <em class="replaceable"><code>c-type</code></em>)</code></span></dt><dd>Type change: A <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a> denoting the same memory
  locations as the original <em class="replaceable"><code>c-place</code></em>, but of type <em class="replaceable"><code>c-type</code></em>.
 </dd><dt><a id="offset"></a><span class="term"><code class="code">(<a class="link" href="#offset"><code class="function">FFI:OFFSET</code></a>
           <em class="replaceable"><code>c-place</code></em> <em class="replaceable"><code>offset</code></em> <em class="replaceable"><code>c-type</code></em>)</code></span></dt><dd>Type change and displacement: return a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a> denoting
  a memory locations displaced from the original <em class="replaceable"><code>c-place</code></em> by an
  <em class="replaceable"><code>offset</code></em> counted in bytes, with type <em class="replaceable"><code>c-type</code></em>.
  This can be used to resize an array, e.g. of <em class="replaceable"><code>c-type</code></em>
  <span class="type"><code class="literal">(<a class="link" href="#c-array"><span class="type">FFI:C-ARRAY</span></a> <span class="type">uint16</span> <em class="replaceable"><code>n</code></em>)</code></span>
  via <code class="code">(<a class="link" href="#offset"><code class="function">FFI:OFFSET</code></a> <em class="replaceable"><code>c-place</code></em> 0 '(<a class="link" href="#c-array"><span class="type">FFI:C-ARRAY</span></a> <span class="type">uint16</span>
   <em class="replaceable"><code>k</code></em>))</code>.
 </dd><dt><a id="c-var-addr"></a><span class="term"><code class="code">(<a class="link" href="#c-var-addr"><code class="function">FFI:C-VAR-ADDRESS</code></a>
           <em class="replaceable"><code>c-place</code></em>)</code></span></dt><dd>Return the address of <em class="replaceable"><code>c-place</code></em> as a Lisp object of
  type <a class="link" href="#faddr"><code class="classname">FFI:FOREIGN-ADDRESS</code></a>.  This is useful as an argument
  to foreign functions expecting a parameter of <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> type <a class="link" href="#c-pointer"><span class="type">FFI:C-POINTER</span></a>.
 </dd><dt><a id="c-var-object"></a><span class="term"><code class="code">(<a class="link" href="#c-var-object"><code class="function">FFI:C-VAR-OBJECT</code></a>
   <em class="replaceable"><code>c-place</code></em>)</code></span></dt><dd>Return the <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a> object underlying the
   <em class="replaceable"><code>c-place</code></em>.  This is also an acceptable argument type to a <a class="link" href="#c-pointer"><span class="type">FFI:C-POINTER</span></a>
   declaration.</dd><dt><a id="typeof"></a><span class="term"><code class="code">(<a class="link" href="#typeof"><code class="function">FFI:TYPEOF</code></a> <em class="replaceable"><code>c-place</code></em>)</code></span></dt><dd>returns the <em class="replaceable"><code>c-type</code></em> corresponding to the <em class="replaceable"><code>c-place</code></em>.
</dd><dt><a id="sizeof"></a><span class="term"><code class="code">(<a class="link" href="#sizeof"><code class="function">FFI:SIZEOF</code></a> <em class="replaceable"><code>c-type</code></em>)</code><br /></span><span class="term"><code class="code">(<a class="link" href="#sizeof"><code class="function">FFI:SIZEOF</code></a> <em class="replaceable"><code>c-place</code></em>)</code></span></dt><dd><p class="simpara">The first form returns the size and alignment of the
   <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> type <em class="replaceable"><code>c-type</code></em>, measured in bytes.</p><p class="simpara">The second form returns the size and alignment of the
   <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> type of <em class="replaceable"><code>c-place</code></em>, measured in bytes.
</p></dd><dt><a id="bitsizeof"></a><span class="term"><code class="code">(<a class="link" href="#bitsizeof"><code class="function">FFI:BITSIZEOF</code></a> <em class="replaceable"><code>c-type</code></em>)</code><br /></span><span class="term"><code class="code">(<a class="link" href="#bitsizeof"><code class="function">FFI:BITSIZEOF</code></a> <em class="replaceable"><code>c-place</code></em>)</code></span></dt><dd><p class="simpara">The first form returns the size and alignment of the
   <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> type <em class="replaceable"><code>c-type</code></em>, measured in bits.</p><p class="simpara">The second form returns the size and alignment of the
   <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> type of <em class="replaceable"><code>c-place</code></em>, measured in bits.
</p></dd><dt><a id="faddr-u"></a><span class="term"><code class="code">(<a class="link" href="#faddr-u"><code class="function">FFI:FOREIGN-ADDRESS-UNSIGNED</code></a> <em class="replaceable"><code>foreign-entity</code></em>)</code><br /></span><span class="term"><code class="code">(<a class="link" href="#faddr-u"><code class="function">FFI:UNSIGNED-FOREIGN-ADDRESS</code></a> <em class="replaceable"><code>number</code></em>)</code></span></dt><dd><p class="simpara"><a class="link" href="#faddr-u"><code class="function">FFI:FOREIGN-ADDRESS-UNSIGNED</code></a> returns the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>
   address embodied in the Lisp object of type <a class="link" href="#faddr"><code class="classname">FFI:FOREIGN-ADDRESS</code></a>,
   <a class="link" href="#fptr"><code class="classname">FFI:FOREIGN-POINTER</code></a>, <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a> or <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a>.</p><p class="simpara"><a class="link" href="#faddr-u"><code class="function">FFI:UNSIGNED-FOREIGN-ADDRESS</code></a> returns a <a class="link" href="#faddr"><code class="classname">FFI:FOREIGN-ADDRESS</code></a>
   object pointing to the given <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> address.
</p></dd><dt><a id="faddr"></a><span class="term"><code class="code">(<a class="link" href="#faddr"><code class="function">FFI:FOREIGN-ADDRESS</code></a> <em class="replaceable"><code>foreign-entity</code></em>)</code></span></dt><dd><p class="simpara"><a class="link" href="#faddr"><code class="function">FFI:FOREIGN-ADDRESS</code></a> is both a type name and a
   selector/constructor function. It is the Lisp object type
   corresponding to a <a class="link" href="#c-pointer"><span class="type">FFI:C-POINTER</span></a> external type declaration, e.g. a
   call-out function with <code class="code">(<code class="constant">:RETURN-TYPE</code> <a class="link" href="#c-pointer"><span class="type">FFI:C-POINTER</span></a>)</code> yields
   a Lisp object of type <a class="link" href="#faddr"><code class="classname">FFI:FOREIGN-ADDRESS</code></a>.</p><p class="simpara">The function extracts the object of type <a class="link" href="#faddr"><code class="classname">FFI:FOREIGN-ADDRESS</code></a>
   living within any <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a> or <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a> object.
   If the <em class="replaceable"><code>foreign-entity</code></em> already is a <a class="link" href="#faddr"><code class="classname">FFI:FOREIGN-ADDRESS</code></a>, it returns it.
   If it is a <a class="link" href="#fptr"><code class="classname">FFI:FOREIGN-POINTER</code></a> (e.g. a base foreign library address),
   it encapsulates it into a <a class="link" href="#faddr"><code class="classname">FFI:FOREIGN-ADDRESS</code></a> object, as suitable
   for use with a <a class="link" href="#c-pointer"><span class="type">FFI:C-POINTER</span></a> external type declaration.
   It does not construct addresses out of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_number.html" target="_top"><code class="classname">NUMBER</code></a>s,
   <a class="link" href="#faddr-u"><code class="function">FFI:UNSIGNED-FOREIGN-ADDRESS</code></a> must be used for that purpose.
</p></dd><dt><a id="dffi-make-var"></a><span class="term"><code class="code">(<a class="link" href="#dffi-make-var"><code class="function">FFI:FOREIGN-VARIABLE</code></a> <em class="replaceable"><code>foreign-entity</code></em>
   <em class="replaceable"><code>c-type-internal</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <em class="replaceable"><code>name</code></em>)</code></span></dt><dd> This constructor creates a new <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a>
   from the given <a class="link" href="#faddr"><code class="classname">FFI:FOREIGN-ADDRESS</code></a> or <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a> and the
   internal <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> type descriptor (as obtained from <a class="link" href="#c-type-parse"><code class="function">FFI:PARSE-C-TYPE</code></a>).
   <em class="replaceable"><code>name</code></em>, a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>, is mostly useful for documentation and
   interactive debugging since it appears in the printed representation
   of the <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a> object, as in
   <code class="computeroutput">#&lt;<a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a> "foo"
    #x0ADD4E55&gt;</code>.
   In effect, this is similar to <a class="link" href="#cast"><code class="function">FFI:CAST</code></a> (or rather
   <code class="code">(<a class="link" href="#offset"><code class="function">FFI:OFFSET</code></a> ... 0 ...)</code> for places),
   except that it works with <a class="link" href="#faddr"><code class="function">FFI:FOREIGN-ADDRESS</code></a> objects and allows
   caching of the internal <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> types.</dd><dt><a id="dffi-make-func"></a><span class="term"><code class="code">(<a class="link" href="#dffi-make-func"><code class="function">FFI:FOREIGN-FUNCTION</code></a>
   <em class="replaceable"><code>foreign-entity</code></em> <em class="replaceable"><code>c-type-internal</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <em class="replaceable"><code>name</code></em>)</code></span></dt><dd><p class="simpara">This constructor creates a <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a>
   from the given <a class="link" href="#faddr"><code class="classname">FFI:FOREIGN-ADDRESS</code></a> or <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a> and the
   internal <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> type descriptor (as obtained from
   <code class="code">(<a class="link" href="#c-type-parse"><code class="function">FFI:PARSE-C-TYPE</code></a> '(<a class="link" href="#c-function"><span class="type">FFI:C-FUNCTION</span></a> ...))</code>,
   in which case it is important to specify the <a class="link" href="#c-flavor" title="32.3.4. The choice of the C flavor"><code class="constant">:LANGUAGE</code></a> because the
   expressions are likely to be evaluated at run time, outside the <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#compilation_unit">compilation unit</a>).
   The <em class="replaceable"><code>name</code></em>, a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>, is mostly useful for documentation and
   interactive debugging since it appears in the printed representation
   of the <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a> object, e.g.,
   <code class="computeroutput">#&lt;<a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a> "foo"
    #x0052B060&gt;</code>.
   It is inherited from the given <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a> object when
   available.</p><p class="simpara">See also <a class="xref" href="#dffi-functions" title="32.3.7. Foreign functions">Section 32.3.7, “Foreign functions”</a>.</p></dd><dt><a id="validp"></a><span class="term"><code class="code">(<a class="link" href="#validp"><code class="function">FFI:VALIDP</code></a> <em class="replaceable"><code>foreign-entity</code></em>)</code><br /></span><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="link" href="#validp"><code class="function">FFI:VALIDP</code></a> <em class="replaceable"><code>foreign-entity</code></em>) <em class="replaceable"><code>value</code></em>)</code></span></dt><dd><p class="simpara">This predicate returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if the <em class="replaceable"><code>foreign-entity</code></em>
  (e.g. the Lisp equivalent of a <a class="link" href="#c-pointer"><span class="type">FFI:C-POINTER</span></a>) refers to a pointer
  which is invalid (e.g., because it comes from a previous Lisp session).
  It returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> if <em class="replaceable"><code>foreign-entity</code></em> can be used within the current Lisp process
  (thus it returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> for all non-foreign arguments).</p><p class="simpara">You can invalidate a foreign object using
  <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="link" href="#validp"><code class="function">FFI:VALIDP</code></a>)</code>.
  You cannot resurrect a zombie, nor can you kill a non-foreign object.
</p></dd><dt><a id="fptr"></a><span class="term"><code class="code">(<a class="link" href="#fptr"><code class="function">FFI:FOREIGN-POINTER</code></a> <em class="replaceable"><code>foreign-entity</code></em>)</code></span></dt><dd><a class="link" href="#fptr"><code class="function">FFI:FOREIGN-POINTER</code></a> returns the <a class="link" href="#fptr"><code class="classname">FFI:FOREIGN-POINTER</code></a>
   associated with the Lisp object of type <a class="link" href="#faddr"><code class="classname">FFI:FOREIGN-ADDRESS</code></a>,
   <a class="link" href="#fptr"><code class="classname">FFI:FOREIGN-POINTER</code></a>, <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a> or <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a>.
</dd><dt><span class="term"><code class="code">(<a class="link" href="#fptr"><code class="function">FFI:SET-FOREIGN-POINTER</code></a> <em class="replaceable"><code>foreign-entity</code></em> {<em class="replaceable"><code>foreign-entity</code></em> |
   <code class="constant">:COPY</code>})</code></span></dt><dd><a class="link" href="#fptr"><code class="function">FFI:SET-FOREIGN-POINTER</code></a> changes the
   <a class="link" href="#fptr"><code class="classname">FFI:FOREIGN-POINTER</code></a> associated with the Lisp object of type
   <a class="link" href="#faddr"><code class="classname">FFI:FOREIGN-ADDRESS</code></a>, <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a> or <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a> to
   that of the other entity.
   With <code class="constant">:COPY</code>, a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_f.html#fresh">fresh</a> <a class="link" href="#fptr"><code class="classname">FFI:FOREIGN-POINTER</code></a> is allocated.
   The original <em class="replaceable"><code>foreign-entity</code></em> still points to the same object and is returned.
   This is particularly useful with <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="link" href="#validp"><code class="function">FFI:VALIDP</code></a>)</code>,
   see <a class="xref" href="#ex-dffi-validity" title="Example 32.11. Controlling validity of resources">Example 32.11, “Controlling validity of resources”</a>.</dd><dt><a id="foreign-stack"></a><span class="term"><code class="code">(<a class="link" href="#foreign-stack"><code class="function">FFI:WITH-FOREIGN-OBJECT</code></a> (<em class="replaceable"><code>variable</code></em> <em class="replaceable"><code>c-type</code></em>
      [<em class="replaceable"><code>initarg</code></em>]) <em class="replaceable"><code>body</code></em>)</code><br /></span><span class="term"><code class="code">(<a class="link" href="#foreign-stack"><code class="function">FFI:WITH-C-VAR</code></a> (<em class="replaceable"><code>variable</code></em> <em class="replaceable"><code>c-type</code></em>
      [<em class="replaceable"><code>initarg</code></em>]) <em class="replaceable"><code>body</code></em>)</code></span></dt><dd><p class="simpara">These forms allocate space on the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> execution
  stack, bind respectively a <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a> object or
  a local <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-symbol-macro.html"><code class="classname">SYMBOL-MACRO</code></a> to <em class="replaceable"><code>variable</code></em> and execute <em class="replaceable"><code>body</code></em>.</p><p class="simpara">When <em class="replaceable"><code>initarg</code></em> is not supplied,
  they allocate space only for <code class="code">(<a class="link" href="#sizeof"><code class="function">FFI:SIZEOF</code></a> <em class="replaceable"><code>c-type</code></em>)</code> bytes.
  This space is filled with zeroes.  E.g.,
  using a <em class="replaceable"><code>c-type</code></em> of <a class="link" href="#c-string"><span class="type">FFI:C-STRING</span></a> or even <span class="type"><code class="literal">(<a class="link" href="#c-ptr"><span class="type">FFI:C-PTR</span></a>
  (<a class="link" href="#c-array"><span class="type">FFI:C-ARRAY</span></a> <span class="type">uint8</span> 32))</code></span> (!) both allocate space
  for a single pointer, initialized to <code class="constant">NULL</code>.</p><p>When <em class="replaceable"><code>initarg</code></em> is supplied, they
  allocate space for an arbitrarily complex set of structures rooted in
  <em class="replaceable"><code>c-type</code></em>.  Therefore, <a class="link" href="#c-array-max"><span class="type">FFI:C-ARRAY-MAX</span></a>, <span class="data"><code class="literal">#()</code></span>
  and <span class="data"><code class="literal">""</code></span> are your friends for creating a
  pointer to the empty arrays:
</p><pre class="programlisting">(with-c-var (v '(c-ptr (c-array-max uint8 32)) #())
  (setf (element (deref v) 0) 127) v)</pre><p>
  <em class="replaceable"><code>c-type</code></em> is evaluated, making creation of variable sized buffers easy:
</p><pre class="programlisting">(with-c-var (fv `(c-array uint8 ,(length my-vector)) my-vector)
  (print fv))</pre><p>
 </p></dd><dt><a id="foreign-value"></a><span class="term"><code class="code">(<a class="link" href="#foreign-value"><code class="function">FFI:FOREIGN-VALUE</code></a> <a class="link" href="#dffi-make-var"><code class="function">FFI:FOREIGN-VARIABLE</code></a>)</code><br /></span><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="link" href="#foreign-value"><code class="function">FFI:FOREIGN-VALUE</code></a> <a class="link" href="#dffi-make-var"><code class="function">FFI:FOREIGN-VARIABLE</code></a>) ...)</code></span></dt><dd><p class="simpara">This functions converts the reference to a <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>
  data structure which the <a class="link" href="#dffi-make-var"><code class="function">FFI:FOREIGN-VARIABLE</code></a> describes, to Lisp. Such a
  reference is typically obtained from <a class="link" href="#foreign-heap"><code class="function">FFI:ALLOCATE-SHALLOW</code></a>,
  <a class="link" href="#foreign-heap"><code class="function">FFI:ALLOCATE-DEEP</code></a>, <a class="link" href="#foreign-heap"><code class="function">FFI:FOREIGN-ALLOCATE</code></a> or via a <code class="code">(<a class="link" href="#c-pointer"><span class="type">FFI:C-POINTER</span></a>
  <em class="replaceable"><code>c-type</code></em>)</code> <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> type description.
  Alternatively, macros like <a class="link" href="#with-c-place"><code class="function">FFI:WITH-C-PLACE</code></a> or <a class="link" href="#foreign-stack"><code class="function">FFI:WITH-C-VAR</code></a> and the
  concept of foreign <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a> hide many uses of this function.</p><p class="simpara">The <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> form performs conversion from Lisp to <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>,
  following to the <a class="link" href="#dffi-make-var"><code class="function">FFI:FOREIGN-VARIABLE</code></a>'s type description.
</p></dd><dt><a id="foreign-stack-string"></a><span class="term"><code class="code">(<a class="link" href="#foreign-stack-string"><code class="function">FFI:WITH-FOREIGN-STRING</code></a>
   (<em class="replaceable"><code>foreign-address</code></em> <em class="replaceable"><code>char-count</code></em>
    <em class="replaceable"><code>byte-count</code></em> <em class="replaceable"><code>string</code></em>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <em class="replaceable"><code>encoding</code></em> <em class="replaceable"><code>null-terminated-p</code></em>
    <em class="replaceable"><code>start</code></em> <em class="replaceable"><code>end</code></em>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> <em class="replaceable"><code>body</code></em>)</code></span></dt><dd><p class="simpara">This forms converts a Lisp <em class="replaceable"><code>string</code></em> according to
   the <em class="replaceable"><code>encoding</code></em>, allocating space on the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> execution stack.
   <em class="replaceable"><code>encoding</code></em> can be any <a class="link" href="#encoding" title="31.5. Encodings"><code class="classname">EXT:ENCODING</code></a>, e.g. <a class="link" href="#charset-UTF-16"><code class="constant">CHARSET:UTF-16</code></a> or <a class="link" href="#charset-UTF-8"><code class="constant">CHARSET:UTF-8</code></a>,
   whereas <a href="impnotes.html#foreign-enc" class="olink"><code class="varname">CUSTOM:*FOREIGN-ENCODING*</code></a> must be an <a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a>-compatible encoding.
   </p><p class="simpara"><em class="replaceable"><code>body</code></em> is then executed with the three variables <em class="replaceable"><code>foreign-address</code></em>,
   <em class="replaceable"><code>char-count</code></em> and
   <em class="replaceable"><code>byte-count</code></em> respectively bound to an
   untyped <a class="link" href="#faddr"><code class="classname">FFI:FOREIGN-ADDRESS</code></a> (as known from the <a class="link" href="#c-pointer"><span class="type">FFI:C-POINTER</span></a> foreign
   type specification) pointing to the stack location, the number of
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>s of the Lisp <em class="replaceable"><code>string</code></em> that were considered and the
   number of <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span> bytes that were allocated for it on the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>
   stack.</p><p class="simpara">When <em class="replaceable"><code>null-terminated-p</code></em> is true,
   which is the default, a variable number of zero bytes is appended,
   depending on the encoding, e.g. 2 for <a class="link" href="#charset-UTF-16"><code class="constant">CHARSET:UTF-16</code></a>,
   and accounted for in <em class="replaceable"><code>byte-count</code></em>,
   and <em class="replaceable"><code>char-count</code></em> is incremented by one.</p><p class="simpara">The <a class="link" href="#faddr"><code class="classname">FFI:FOREIGN-ADDRESS</code></a> object bound to <em class="replaceable"><code>foreign-address</code></em> is
   invalidated upon the exit from the form.</p><p>A stupid example (a quite costly interface
   to <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/mblen.html"><code class="function">mblen</code></a>):
</p><pre class="programlisting">(with-foreign-string (fv elems bytes string
                      :encoding charset:jis... :null-terminated-p nil
                      :end 5)
 (declare (ignore fv elems))
 (format t "This string would take ~D bytes." bytes))</pre><p>
</p></dd><dt><a id="c-type-parse"></a><span class="term"><code class="code">(<a class="link" href="#c-type-parse"><code class="function">FFI:PARSE-C-TYPE</code></a> <em class="replaceable"><code>c-type</code></em>)</code><br /></span><span class="term"><code class="code">(<a class="link" href="#c-type-parse"><code class="function">FFI:DEPARSE-C-TYPE</code></a> <em class="replaceable"><code>c-type-internal</code></em>)</code></span></dt><dd><p class="simpara">Convert between the external (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>) and internal
   (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a>) <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> type representations (used by <a href="impnotes.html#describe" class="olink"><code class="function">DESCRIBE</code></a>).
  </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>Although you can memoize a <em class="replaceable"><code>c-type-internal</code></em> (see
    <a class="xref" href="#memoized" title="31.11.3. Macro EXT:MEMOIZED">Section 31.11.3, “Macro <code class="function">EXT:MEMOIZED</code>”</a> - but do not expect type redefinitions to
    work across memoization!), you cannot serialize it (write to
    disk) because deserialization loses object identity.</p></div></dd><dt><a id="foreign-heap"></a><span class="term"><code class="code">(<a class="link" href="#foreign-heap"><code class="function">FFI:ALLOCATE-SHALLOW</code></a>
   <em class="replaceable"><code>c-type</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:COUNT</code> <code class="constant">:READ-ONLY</code>)</code><br /></span><span class="term"><code class="code">(<a class="link" href="#foreign-heap"><code class="function">FFI:ALLOCATE-DEEP</code></a> <em class="replaceable"><code>c-type</code></em> <em class="replaceable"><code>contents</code></em>
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:COUNT</code> <code class="constant">:READ-ONLY</code>)</code><br /></span><span class="term"><code class="code">(<a class="link" href="#foreign-heap"><code class="function">FFI:FOREIGN-FREE</code></a> <em class="replaceable"><code>foreign-entity</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :FULL)</code><br /></span><span class="term"><code class="code">(<a class="link" href="#foreign-heap"><code class="function">FFI:FOREIGN-ALLOCATE</code></a> <em class="replaceable"><code>c-type-internal</code></em>
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :INITIAL-CONTENTS <code class="constant">:COUNT</code> <code class="constant">:READ-ONLY</code>)</code></span></dt><dd><p class="simpara">Macro <a class="link" href="#foreign-heap"><code class="function">FFI:ALLOCATE-SHALLOW</code></a> allocates
   <code class="code">(<a class="link" href="#sizeof"><code class="function">FFI:SIZEOF</code></a> <em class="replaceable"><code>c-type</code></em>)</code>
   bytes on the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> heap and zeroes them out
   (like <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/calloc.html"><code class="function">calloc</code></a>).
   When <code class="constant">:COUNT</code> is supplied, <em class="replaceable"><code>c-type</code></em> is substituted with
   <span class="type"><code class="literal">(<a class="link" href="#c-array"><span class="type">FFI:C-ARRAY</span></a> <em class="replaceable"><code>c-type</code></em> <em class="replaceable"><code>count</code></em>)</code></span>,
   except when <em class="replaceable"><code>c-type</code></em> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>, in which case
   <span class="type"><code class="literal">(<a class="link" href="#c-array-max"><span class="type">FFI:C-ARRAY-MAX</span></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a> <em class="replaceable"><code>count</code></em>)</code></span>
   is used instead.
   When <code class="constant">:READ-ONLY</code> is supplied, the Lisp side is prevented from modifying the
   memory contents.  This can be used as an indication that some foreign
   side is going to fill this memory (e.g. via <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/read.html"><code class="function">read</code></a>).</p><p class="simpara">Returns a <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a> object of the actual <em class="replaceable"><code>c-type</code></em>,
   whose address part points to the newly allocated memory.</p><p class="simpara"><a class="link" href="#foreign-heap"><code class="function">FFI:ALLOCATE-DEEP</code></a> will call <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/malloc.html"><code class="function">malloc</code></a> as many times
   as necessary to build a structure on the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> heap of the given
   <em class="replaceable"><code>c-type</code></em>, initialized from the given <em class="replaceable"><code>contents</code></em>.</p><p class="simpara">E.g., <code class="code">(<a class="link" href="#foreign-heap"><code class="function">FFI:ALLOCATE-DEEP</code></a> '<a class="link" href="#c-string"><span class="type">FFI:C-STRING</span></a> "ABCDE")</code>
    performs 2 allocations: one for a <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> pointer to a string,
    another for the contents of that string.  This would be useful in
    conjunction with a <span class="type">char**</span> <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> type
    declaration.  <code class="code">(<a class="link" href="#foreign-heap"><code class="function">FFI:ALLOCATE-SHALLOW</code></a> '<a class="link" href="#c-string"><span class="type">FFI:C-STRING</span></a>)</code>
    allocates room for a single pointer (probably 4 bytes).</p><p class="simpara"><code class="code">(<a class="link" href="#foreign-heap"><code class="function">FFI:ALLOCATE-DEEP</code></a> '<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a> "ABCDEF" :count
    10)</code> allocates and initializes room for the type <span class="type"><code class="literal">(<a class="link" href="#c-array-max"><span class="type">FFI:C-ARRAY-MAX</span></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a> 10)</code></span>,
    corresponding to <span class="type">char*</span> or, more specifically,
   <span class="type">char[10]</span> in <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>.</p><p class="simpara">Function <a class="link" href="#foreign-heap"><code class="function">FFI:FOREIGN-FREE</code></a> deallocates memory at the address
   held by the given <em class="replaceable"><code>foreign-entity</code></em>. If <code class="constant">:FULL</code> is supplied
   and the argument is of type <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a>, recursively frees
   the whole complex structure pointed to by this variable.</p><p class="simpara">If given a <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a> object that corresponds to a
   <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> callback, deallocates it.  Callbacks are automatically
   created each time you pass a Lisp function via the <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>.</p><p class="simpara">Use <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="link" href="#validp"><code class="function">FFI:VALIDP</code></a>)</code> to disable further
   references to this address from Lisp.  This is currently not done
   automatically.  If the given pointer is already invalid,
   <a class="link" href="#foreign-heap"><code class="function">FFI:FOREIGN-FREE</code></a> (currently) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>. This may change to
   make it easier to integrate with <a class="link" href="#final" title="31.8. Finalization"><code class="function">EXT:FINALIZE</code></a>.</p><p class="simpara">Function <a class="link" href="#foreign-heap"><code class="function">FFI:FOREIGN-ALLOCATE</code></a> is a lower-level interface as it
   requires an internal <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> type descriptor as returned by
   <a class="link" href="#c-type-parse"><code class="function">FFI:PARSE-C-TYPE</code></a>.</p></dd><dt><a id="with-c-place"></a><span class="term"><code class="code">(<a class="link" href="#with-c-place"><code class="function">FFI:WITH-C-PLACE</code></a> (<em class="replaceable"><code>variable</code></em> <em class="replaceable"><code>foreign-entity</code></em>)
   <em class="replaceable"><code>body</code></em>)</code></span></dt><dd><p class="simpara">Create a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a> out of the given <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a>
  object so operations on places (e.g. <a class="link" href="#cast"><code class="function">FFI:CAST</code></a>, <a class="link" href="#deref"><code class="function">FFI:DEREF</code></a>, <a class="link" href="#slot"><code class="function">FFI:SLOT</code></a> etc.) can
  be used within <em class="replaceable"><code>body</code></em>.  <a class="link" href="#foreign-stack"><code class="function">FFI:WITH-C-VAR</code></a> appears as a composition of
  <a class="link" href="#foreign-stack"><code class="function">FFI:WITH-FOREIGN-OBJECT</code></a> and <a class="link" href="#with-c-place"><code class="function">FFI:WITH-C-PLACE</code></a>.</p><p>Such a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a> can be used to access memory referenced by a <em class="replaceable"><code>foreign-entity</code></em>
  object:
  </p><pre class="programlisting">(setq foo (allocate-deep '(c-array uint8 3) rgb))
(with-c-place (place foo) (element place 0))</pre><p>
</p></dd><dt><a id="ffi-extern-output"></a><span class="term"><a class="link" href="#ffi-extern-output"><code class="varname">FFI:*OUTPUT-C-FUNCTIONS*</code></a><br /></span><span class="term"><code class="varname">FFI:*OUTPUT-C-VARIABLES*</code></span></dt><dd><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> will write the <span class="type">extern</span>
   declarations for foreign functions (defined with <a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a>) and
   foreign variables (defined with <a class="link" href="#def-c-var"><code class="function">FFI:DEF-C-VAR</code></a>) into the output <code class="filename">#P".c"</code>
   (when the Lisp file is compiled with <a href="impnotes.html#compilefile" class="olink"><code class="function">COMPILE-FILE</code></a>)
   <span class="emphasis"><em>unless</em></span> these variables are <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
   They are <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> by default, so the <span class="type">extern</span>
   declarations are <span class="strong"><strong>not</strong></span> written; you are encouraged to use
   <a class="link" href="#c-lines"><code class="function">FFI:C-LINES</code></a> to include the appropriate <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> headers.
   Set these variables to non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if the headers are not available or
   not usable.</dd><dt><a id="ffi-guard"></a><span class="term"><a class="link" href="#ffi-guard"><code class="varname">FFI:*FOREIGN-GUARD*</code></a></span></dt><dd><p>When this variable is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> at <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#compile_time">compile time</a>,
  <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> will guard the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> statements in the output file with
  <a class="ulink" href="http://gcc.gnu.org/onlinedocs/cpp/" target="_top"><span class="command"><strong>cpp</strong></span></a> conditionals to take advantage of <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/autoconf/" target="_top">autoconf</a> feature detection.
  E.g., </p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_eval-when.html" target="_top"><code class="function">EVAL-WHEN</code></a> (compile) (setq *foreign-guard* t))
(<a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> some-function (:name "function_name") ...)
</pre><p> will produce </p><pre class="programlisting">
# if defined(HAVE_FUNCTION_NAME)
  register_foreign_function((void*)&amp;function_name,"function_name",1024);
# endif
</pre><p> and will compile and link on any system.</p><p class="simpara">This is mostly useful for product delivery when you want your
  module to build on any system even if some features will not be
  available.</p><p class="simpara"><a class="link" href="#ffi-guard"><code class="varname">FFI:*FOREIGN-GUARD*</code></a> is initialized to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> for backwards compatibility.
</p></dd><dt><a id="fptr-info"></a><span class="term"><a class="link" href="#fptr-info"><code class="function">FFI:FOREIGN-POINTER-INFO</code></a></span></dt><dd>This is an interface
   to <a class="bsd" href="http://www.freebsd.org/cgi/man.cgi?query=dladdr"><code class="function">dladdr</code></a> and it returns the 4 fields
   of <span class="type">Dl_info</span> as <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_m.html#multiple_values">multiple values</a>.</dd></dl></div><div class="variablelist"><a id="dffi-low"></a><p class="title"><strong>Low-level <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> forms</strong></p><dl class="variablelist"><dt><a id="memory-as"></a><span class="term"><code class="code">(<a class="link" href="#memory-as"><code class="function">FFI:MEMORY-AS</code></a> <em class="replaceable"><code>foreign-address</code></em> <em class="replaceable"><code>c-type-internal</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
   <em class="replaceable"><code>offset</code></em>)</code><br /></span><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="link" href="#memory-as"><code class="function">FFI:MEMORY-AS</code></a> <em class="replaceable"><code>foreign-address</code></em> <em class="replaceable"><code>c-type-internal</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
   <em class="replaceable"><code>offset</code></em>) <em class="replaceable"><code>value</code></em>)</code></span></dt><dd><p class="simpara">This accessor is useful when operating with untyped
   foreign pointers (<a class="link" href="#faddr"><code class="classname">FFI:FOREIGN-ADDRESS</code></a>) as opposed to typed ones
   (represented by <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a>).  It allows to type and
   dereference the given pointer without the need to create an object of
   type <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a>.</p><p class="simpara">Alternatively, one could use <code class="code">(<a class="link" href="#foreign-value"><code class="function">FFI:FOREIGN-VALUE</code></a>
    (<a class="link" href="#dffi-make-var"><code class="function">FFI:FOREIGN-VARIABLE</code></a> <em class="replaceable"><code>foreign-entity</code></em> <em class="replaceable"><code>c-type-internal</code></em>))</code>
   (also <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>able).</p><p class="simpara">Note that <em class="replaceable"><code>c-type-internal</code></em> is the <span class="emphasis"><em>internal</em></span>
   representation of a foreign type, thus <a class="link" href="#c-type-parse"><code class="function">FFI:PARSE-C-TYPE</code></a> is required
   with literal names or types, e.g. <code class="code">(<a class="link" href="#memory-as"><code class="function">FFI:MEMORY-AS</code></a> <em class="replaceable"><code>foreign-address</code></em>
    (<a class="link" href="#c-type-parse"><code class="function">FFI:PARSE-C-TYPE</code></a> '(<a class="link" href="#c-array"><span class="type">FFI:C-ARRAY</span></a> uint8 3)))</code> or <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>
    (<a class="link" href="#memory-as"><code class="function">FFI:MEMORY-AS</code></a> <em class="replaceable"><code>foreign-address</code></em> (<a class="link" href="#c-type-parse"><code class="function">FFI:PARSE-C-TYPE</code></a> 'uint32)) 0)</code>.</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="dffi-types"></a>32.3.3. (Foreign) <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> types</h3></div></div></div><p>Foreign <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> types are used in the <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>.
They are <span class="strong"><strong>not</strong></span> regular <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> types or <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> classes.</p><p>A <em class="replaceable"><code>c-type</code></em> is either a predefined <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> type or the name of a
 type defined by <a class="link" href="#def-c-type"><code class="function">FFI:DEF-C-TYPE</code></a>.</p><div class="variablelist"><p class="title"><strong>the predefined <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> types (<em class="replaceable"><code>c-type</code></em>)</strong></p><dl class="variablelist"><dt><a id="simple-c-type"></a><span class="term"><em class="replaceable"><code>simple-c-type</code></em></span></dt><dd><p>the simple <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> types
  </p><div class="informaltable"><a id="simple-c-type-tab"></a><table class="informaltable" border="1"><colgroup><col /><col /><col /><col /><col /></colgroup><thead><tr><th align="center">Lisp name</th><th align="center">Lisp equivalent</th><th align="center"><a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> equivalent</th><th align="center"><a class="ulink" href="http://www2.parc.com/istl/projects/ILU/" target="_top"><acronym class="acronym" title="Inter-Language Unification">ILU</acronym></a> equivalent</th><th align="center">Comment</th></tr></thead><tbody><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></td><td align="center"><span class="type">void</span></td><td align="center"> </td><td align="center">as a result type only</td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_boolean.html" target="_top"><code class="classname">BOOLEAN</code></a></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_boolean.html" target="_top"><code class="classname">BOOLEAN</code></a></td><td align="center"><span class="type">int</span></td><td align="center"><span class="type">BOOLEAN</span></td><td class="auto-generated"> </td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a></td><td align="center"><span class="type">char</span></td><td align="center"><span class="type">SHORT CHARACTER</span></td><td class="auto-generated"> </td></tr><tr><td align="center"><span class="type">char</span></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a></td><td align="center"><span class="type">signed char</span></td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td align="center"><span class="type">uchar</span></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a></td><td align="center"><span class="type">unsigned char</span></td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td align="center"><span class="type">short</span></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a></td><td align="center"><span class="type">short</span></td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td align="center"><span class="type">ushort</span></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a></td><td align="center"><span class="type">unsigned short</span></td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td align="center"><span class="type">int</span></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a></td><td align="center"><span class="type">int</span></td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td align="center"><span class="type">uint</span></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a></td><td align="center"><span class="type">unsigned int</span></td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td align="center"><span class="type">long</span></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a></td><td align="center"><span class="type">long</span></td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td align="center"><span class="type">ulong</span></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a></td><td align="center"><span class="type">unsigned long</span></td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td align="center"><span class="type">uint8</span></td><td align="center"><span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span></td><td align="center"><span class="type">uint8</span></td><td align="center"><span class="type">BYTE</span></td><td class="auto-generated"> </td></tr><tr><td align="center"><span class="type">sint8</span></td><td align="center"><span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_signed-byte.html" target="_top"><code class="classname">SIGNED-BYTE</code></a> 8)</code></span></td><td align="center"><span class="type">sint8</span></td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td align="center"><span class="type">uint16</span></td><td align="center"><span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 16)</code></span></td><td align="center"><span class="type">uint16</span></td><td align="center"><span class="type">SHORT CARDINAL</span></td><td class="auto-generated"> </td></tr><tr><td align="center"><span class="type">sint16</span></td><td align="center"><span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_signed-byte.html" target="_top"><code class="classname">SIGNED-BYTE</code></a> 16)</code></span></td><td align="center"><span class="type">sint16</span></td><td align="center"><span class="type">SHORT INTEGER</span></td><td class="auto-generated"> </td></tr><tr><td align="center"><span class="type">uint32</span></td><td align="center"><span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 32)</code></span></td><td align="center"><span class="type">uint32</span></td><td align="center"><span class="type">CARDINAL</span></td><td class="auto-generated"> </td></tr><tr><td align="center"><span class="type">sint32</span></td><td align="center"><span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_signed-byte.html" target="_top"><code class="classname">SIGNED-BYTE</code></a> 32)</code></span></td><td align="center"><span class="type">sint32</span></td><td align="center"><span class="type">INTEGER</span></td><td class="auto-generated"> </td></tr><tr><td align="center"><span class="type">uint64</span></td><td align="center"><span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 64)</code></span></td><td align="center"><span class="type">uint64</span></td><td align="center"><span class="type">LONG CARDINAL</span></td><td align="center">does not work on all platforms</td></tr><tr><td align="center"><span class="type">sint64</span></td><td align="center"><span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_signed-byte.html" target="_top"><code class="classname">SIGNED-BYTE</code></a> 64)</code></span></td><td align="center"><span class="type">sint64</span></td><td align="center"><span class="type">LONG INTEGER</span></td><td align="center">does not work on all platforms</td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SINGLE-FLOAT</code></a></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SINGLE-FLOAT</code></a></td><td align="center"><span class="type">float</span></td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">DOUBLE-FLOAT</code></a></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">DOUBLE-FLOAT</code></a></td><td align="center"><span class="type">double</span></td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr></tbody></table></div></dd><dt><a id="c-pointer"></a><span class="term"><a class="link" href="#c-pointer"><span class="type">FFI:C-POINTER</span></a></span></dt><dd>This type corresponds to what <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> calls
   <span class="type">void*</span>, an opaque pointer.
   When used as an argument, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> is accepted as a <a class="link" href="#c-pointer"><span class="type">FFI:C-POINTER</span></a> and
   treated as <code class="constant">NULL</code>; when a function wants to return a <code class="constant">NULL</code>
   <a class="link" href="#c-pointer"><span class="type">FFI:C-POINTER</span></a>, it actually returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
</dd><dt><span class="term"><span class="type"><code class="literal">(<a class="link" href="#c-pointer"><span class="type">FFI:C-POINTER</span></a>
  <em class="replaceable"><code>c-type</code></em>)</code></span></span></dt><dd>This type is equivalent to what <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> calls
  <span class="type"><em class="replaceable"><code>c-type</code></em> *</span>: a pointer to a single item of the given
  <em class="replaceable"><code>c-type</code></em>. It differs from <span class="type"><code class="literal">(<a class="link" href="#c-ptr-null"><span class="type">FFI:C-PTR-NULL</span></a>
  <em class="replaceable"><code>c-type</code></em>)</code></span> (see below) in that no conversion to and from
  Lisp will occur (beyond the usual one of the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> <code class="constant">NULL</code> pointer
  to or from Lisp <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>). Instead, an object of type <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a>
  is used to represent the foreign <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a>. It is assimilable to a typed
  pointer.</dd><dt><a id="c-string"></a><span class="term"><a class="link" href="#c-string"><span class="type">FFI:C-STRING</span></a></span></dt><dd>This type corresponds to what <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> calls
  <span class="type">char*</span>, a zero-terminated string.  Its Lisp equivalent is
  a string, without the trailing zero character.
 </dd><dt><a id="c-struct"></a><span class="term"><span class="type"><code class="literal">(<a class="link" href="#c-struct"><span class="type">FFI:C-STRUCT</span></a> <em class="replaceable"><code>class</code></em>
   (<em class="replaceable"><code>ident<sub>1</sub></code></em> <em class="replaceable"><code>c-type<sub>1</sub></code></em>) ... (<em class="replaceable"><code>ident<sub>n</sub></code></em> <em class="replaceable"><code>c-type<sub>n</sub></code></em>))</code></span></span></dt><dd><p class="simpara">This type is equivalent to what <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> calls
   <span class="type">struct { <em class="replaceable"><code>c-type<sub>1</sub></code></em> <em class="replaceable"><code>ident<sub>1</sub></code></em>; ...; <em class="replaceable"><code>c-type<sub>n</sub></code></em> <em class="replaceable"><code>ident<sub>n</sub></code></em>; }</span>.
   Its Lisp equivalent is: if <em class="replaceable"><code>class</code></em> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a>, a
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-vector.html" target="_top"><code class="classname">SIMPLE-VECTOR</code></a>; if <em class="replaceable"><code>class</code></em> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>, a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#proper_list">proper list</a>;
   if <em class="replaceable"><code>class</code></em> is a symbol naming a structure or <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> class, an
   instance of this class, with slots of names
   <em class="replaceable"><code>ident<sub>1</sub></code></em>, ..., <em class="replaceable"><code>ident<sub>n</sub></code></em>.</p><p class="simpara">
   <em class="replaceable"><code>class</code></em> may also be a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_cons.html" target="_top"><code class="classname">CONS</code></a> of a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a> (as above) and
   a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of <a class="link" href="#def-c-struct"><code class="function">FFI:DEF-C-STRUCT</code></a> options.
</p></dd><dt><a id="c-union"></a><span class="term"><span class="type"><code class="literal">(<a class="link" href="#c-union"><span class="type">FFI:C-UNION</span></a>
   (<em class="replaceable"><code>ident<sub>1</sub></code></em> <em class="replaceable"><code>c-type<sub>1</sub></code></em>) ... (<em class="replaceable"><code>ident<sub>n</sub></code></em> <em class="replaceable"><code>c-type<sub>n</sub></code></em>))</code></span></span></dt><dd>This type is equivalent to what <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> calls
   <span class="type">union { <em class="replaceable"><code>c-type<sub>1</sub></code></em> <em class="replaceable"><code>ident<sub>1</sub></code></em>; ...; <em class="replaceable"><code>c-type<sub>n</sub></code></em> <em class="replaceable"><code>ident<sub>n</sub></code></em>; }</span>.
   Conversion to and from Lisp assumes that a value is to be viewed as
   being of <em class="replaceable"><code>c-type<sub>1</sub></code></em>.
</dd><dt><a id="c-array"></a><span class="term"><span class="type"><code class="literal">(<a class="link" href="#c-array"><span class="type">FFI:C-ARRAY</span></a>
   <em class="replaceable"><code>c-type</code></em> <em class="replaceable"><code>dim<sub>1</sub></code></em>)</code></span><br /></span><span class="term"><span class="type"><code class="literal">(<a class="link" href="#c-array"><span class="type">FFI:C-ARRAY</span></a> <em class="replaceable"><code>c-type</code></em> (<em class="replaceable"><code>dim<sub>1</sub></code></em>
   ... <em class="replaceable"><code>dim<sub>n</sub></code></em>))</code></span></span></dt><dd>This type is equivalent to what <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> calls
   <span class="type"><em class="replaceable"><code>c-type</code></em> [<em class="replaceable"><code>dim<sub>1</sub></code></em>] ... [<em class="replaceable"><code>dim<sub>n</sub></code></em>]</span>.
   Note that when an array is passed as an argument to a function in
   <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>, it is actually passed as a pointer; you therefore have to
   write <span class="type"><code class="literal">(<a class="link" href="#c-ptr"><span class="type">FFI:C-PTR</span></a> (<a class="link" href="#c-array"><span class="type">FFI:C-ARRAY</span></a> ...))</code></span> for this
   argument's type.</dd><dt><a id="c-array-max"></a><span class="term"><span class="type"><code class="literal">(<a class="link" href="#c-array-max"><span class="type">FFI:C-ARRAY-MAX</span></a>
   <em class="replaceable"><code>c-type</code></em> <em class="replaceable"><code>maxdimension</code></em>)</code></span></span></dt><dd>This type is equivalent to what <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> calls
   <span class="type"><em class="replaceable"><code>c-type</code></em> [<em class="replaceable"><code>maxdimension</code></em>]</span>, an array containing up to
   <em class="replaceable"><code>maxdimension</code></em> elements.
   The array is zero-terminated if it contains less than <em class="replaceable"><code>maxdimension</code></em> elements.
   Conversion from Lisp of an array with more than <em class="replaceable"><code>maxdimension</code></em> elements
   silently ignores the extra elements.
</dd><dt><a id="c-function"></a><span class="term"><span class="type"><code class="literal">(<a class="link" href="#c-function"><span class="type">FFI:C-FUNCTION</span></a> (<code class="constant">:ARGUMENTS</code>
      {(<em class="replaceable"><code>argument</code></em> <em class="replaceable"><code>a-c-type</code></em>
        [<a class="link" href="#param-mode" title="32.3.9. Parameter Mode"><em class="replaceable"><code>PARAM-MODE</code></em></a> [<a class="link" href="#allocation" title="32.3.8. Argument and result passing conventions"><em class="replaceable"><code>ALLOCATION</code></em></a>]])}*)
    (<code class="constant">:RETURN-TYPE</code> <em class="replaceable"><code>r-c-type</code></em> [<a class="link" href="#allocation" title="32.3.8. Argument and result passing conventions"><em class="replaceable"><code>ALLOCATION</code></em></a>])
    (<a class="link" href="#c-flavor" title="32.3.4. The choice of the C flavor"><code class="constant">:LANGUAGE</code></a> <em class="replaceable"><code>language</code></em>))</code></span></span></dt><dd>This type designates a <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> function that can be
  called according to the given prototype
   <code class="code">(<em class="replaceable"><code>r-c-type</code></em> (*)
    (<em class="replaceable"><code>a-c-type<sub>1</sub></code></em>, ...))</code>.
  Conversion between <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> functions and Lisp functions
  is transparent, and <code class="constant">NULL</code>/<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> is recognized and
  accepted.</dd><dt><a id="c-ptr"></a><span class="term"><span class="type"><code class="literal">(<a class="link" href="#c-ptr"><span class="type">FFI:C-PTR</span></a> <em class="replaceable"><code>c-type</code></em>)</code></span></span></dt><dd>This type is equivalent to what <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> calls
   <span class="type"><em class="replaceable"><code>c-type</code></em> *</span>: a pointer to a single item of the given
   <em class="replaceable"><code>c-type</code></em>.</dd><dt><a id="c-ptr-null"></a><span class="term"><span class="type"><code class="literal">(<a class="link" href="#c-ptr-null"><span class="type">FFI:C-PTR-NULL</span></a> <em class="replaceable"><code>c-type</code></em>)</code></span></span></dt><dd>This type is also equivalent to what <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> calls
   <span class="type"><em class="replaceable"><code>c-type</code></em> *</span>: a pointer to a single item of the given
   <em class="replaceable"><code>c-type</code></em>, with the exception that <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> <code class="constant">NULL</code> corresponds to
   Lisp <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</dd><dt><a id="c-array-ptr"></a><span class="term"><span class="type"><code class="literal">(<a class="link" href="#c-array-ptr"><span class="type">FFI:C-ARRAY-PTR</span></a> <em class="replaceable"><code>c-type</code></em>)</code></span></span></dt><dd>This type is equivalent to what <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> calls
   <span class="type"><em class="replaceable"><code>c-type</code></em> (*)[]</span>: a pointer to a zero-terminated array of
   items of the given <em class="replaceable"><code>c-type</code></em>.</dd></dl></div><p>The conversion of <a class="link" href="#c-string"><span class="type">FFI:C-STRING</span></a>,
 <span class="type"><code class="literal">(<a class="link" href="#c-array"><span class="type">FFI:C-ARRAY</span></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a> <em class="replaceable"><code>dim<sub>1</sub></code></em>)</code></span>,
 <span class="type"><code class="literal">(<a class="link" href="#c-array-max"><span class="type">FFI:C-ARRAY-MAX</span></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a> <em class="replaceable"><code>maxdimension</code></em>)</code></span>,
 <span class="type"><code class="literal">(<a class="link" href="#c-array-ptr"><span class="type">FFI:C-ARRAY-PTR</span></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>)</code></span>
 is governed by <a href="impnotes.html#foreign-enc" class="olink"><code class="varname">CUSTOM:*FOREIGN-ENCODING*</code></a> and dimensions are given
 in <span class="emphasis"><em>bytes</em></span>.
 The conversion of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>, and as such of
 <span class="type"><code class="literal">(<a class="link" href="#c-ptr"><span class="type">FFI:C-PTR</span></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>)</code></span>, or
 <span class="type"><code class="literal">(<a class="link" href="#c-ptr-null"><span class="type">FFI:C-PTR-NULL</span></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>)</code></span>, as well as
 that of multi-dimensional arrays <span class="type"><code class="literal">(<a class="link" href="#c-array"><span class="type">FFI:C-ARRAY</span></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>
 (<em class="replaceable"><code>dim<sub>1</sub></code></em> ... <em class="replaceable"><code>dim<sub>n</sub></code></em>))</code></span>, are governed by <a href="impnotes.html#foreign-enc" class="olink"><code class="varname">CUSTOM:*FOREIGN-ENCODING*</code></a> if
 the latter is a <a class="link" href="#enc1-1" title="“1:1” encodings"><span class="quote">“<span class="quote">1:1</span>”</span> encoding</a>, or by the <a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a> encoding otherwise.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>Remember that the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> type <span class="type">char</span> is
  a <span class="emphasis"><em>numeric</em></span> type and does not use <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>
  <a class="link" href="#encoding" title="31.5. Encodings"><code class="classname">EXT:ENCODING</code></a>s.</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="c-flavor"></a>32.3.4. The choice of the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> flavor</h3></div></div></div><p><a class="link" href="#c-function"><span class="type">FFI:C-FUNCTION</span></a>, <a class="link" href="#def-call-in"><code class="function">FFI:DEF-CALL-IN</code></a>, <a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> take a <a class="link" href="#c-flavor" title="32.3.4. The choice of the C flavor"><code class="constant">:LANGUAGE</code></a> argument.
The <em class="replaceable"><code>language</code></em> is either <code class="constant">:C</code> (denotes K&amp;R <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>) or <code class="constant">:STDC</code>
(denotes <a class="ulink" href="http://www.ansi.org/" target="_top"><acronym class="acronym" title="The American National Standards Institute">ANSI</acronym></a> <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>) or <code class="constant">:STDC-STDCALL</code> (denotes <a class="ulink" href="http://www.ansi.org/" target="_top"><acronym class="acronym" title="The American National Standards Institute">ANSI</acronym></a> <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>
with the <a class="" href="http://www.google.com/search?q=stdcall">stdcall</a> calling convention).
It specifies whether the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> function (caller or callee) has been
compiled by a K&amp;R <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> compiler or by an <a class="ulink" href="http://www.ansi.org/" target="_top"><acronym class="acronym" title="The American National Standards Institute">ANSI</acronym></a> <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> compiler,
and possibly the calling convention.</p><p>The default language is set using the macro
 <strong class="first"><em class="firstterm"><a class="link" href="#c-flavor" title="32.3.4. The choice of the C flavor"><code class="function">FFI:DEFAULT-FOREIGN-LANGUAGE</code></a>
  <a id="dflt-ffi-lang" class="indexterm"></a></em></strong>.
 If this macro has not been called in the current <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#compilation_unit">compilation unit</a>
 (usually a file), a warning is issued and <code class="constant">:STDC</code> is used for the rest
 of the unit.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="dffi-variables"></a>32.3.5. Foreign variables</h3></div></div></div><p><strong class="first"><em class="firstterm">Foreign variables<a id="dffi-fv" class="indexterm"></a></em></strong> are variables whose
 storage is allocated in the foreign language module.
 They can nevertheless be evaluated and modified through <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/spefor_setq.html" target="_top"><code class="function">SETQ</code></a>,
 just as normal variables can, except that the range of allowed values
 is limited according to the variable's foreign type.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="dffi-eq"></a>Equality of foreign values</h3><p>For a foreign variable <em class="replaceable"><code>x</code></em> the form <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eql.html" target="_top"><code class="function">EQL</code></a> <em class="replaceable"><code>x</code></em>
   <em class="replaceable"><code>x</code></em>)</code> is not necessarily true, since every time <em class="replaceable"><code>x</code></em> is
  evaluated its foreign value is converted to a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_f.html#fresh">fresh</a> Lisp value.
  Ergo, <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_aref.html" target="_top"><code class="function">AREF</code></a> <em class="replaceable"><code>x</code></em> <em class="replaceable"><code>n</code></em>) <em class="replaceable"><code>y</code></em>)</code> modifies this
  <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_f.html#fresh">fresh</a> Lisp value (immediately discarded), <span class="strong"><strong>not</strong></span> the foreign data.
  Use <a class="link" href="#element"><code class="function">FFI:ELEMENT</code></a> et al instead, see <a class="xref" href="#dffi-places" title="32.3.6. Operations on foreign places">Section 32.3.6, “Operations on foreign places”</a>.
</p></div><p>Foreign variables are defined using <a class="link" href="#def-c-var"><code class="function">FFI:DEF-C-VAR</code></a> and <a class="link" href="#foreign-stack"><code class="function">FFI:WITH-C-VAR</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="dffi-places"></a>32.3.6. Operations on foreign places</h3></div></div></div><p>A <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a> <em class="replaceable"><code>name</code></em> defined by <a class="link" href="#def-c-var"><code class="function">FFI:DEF-C-VAR</code></a>, <a class="link" href="#foreign-stack"><code class="function">FFI:WITH-C-VAR</code></a>
 or <a class="link" href="#with-c-place"><code class="function">FFI:WITH-C-PLACE</code></a> defines a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a>,
 i.e., a form which can also be used as argument to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>.
 (An <a class="dict" href="http://foldoc.org/lvalue"><span class="quote">“<span class="quote">lvalue</span>”</span></a> in <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> terminology.)
 The following operations are available on foreign places:
 </p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="link" href="#element"><code class="function">FFI:ELEMENT</code></a></td><td><a class="link" href="#c-var-addr"><code class="function">FFI:C-VAR-ADDRESS</code></a></td></tr><tr><td><a class="link" href="#deref"><code class="function">FFI:DEREF</code></a></td><td><a class="link" href="#c-var-object"><code class="function">FFI:C-VAR-OBJECT</code></a></td></tr><tr><td><a class="link" href="#slot"><code class="function">FFI:SLOT</code></a></td><td><a class="link" href="#typeof"><code class="function">FFI:TYPEOF</code></a></td></tr><tr><td><a class="link" href="#cast"><code class="function">FFI:CAST</code></a></td><td><a class="link" href="#sizeof"><code class="function">FFI:SIZEOF</code></a></td></tr><tr><td><a class="link" href="#offset"><code class="function">FFI:OFFSET</code></a></td><td><a class="link" href="#bitsizeof"><code class="function">FFI:BITSIZEOF</code></a></td></tr></table></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="dffi-functions"></a>32.3.7. Foreign functions</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#dffi-callback-mem">32.3.7.1. Callbacks and memory management</a></span></dt></dl></div><p>Foreign functions are functions which are defined in the foreign language.
 There are <strong class="first"><em class="firstterm">named foreign functions<a id="dffi-ff-n" class="indexterm"></a></em></strong>
 (imported via <a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> or created via <a class="link" href="#def-call-in"><code class="function">FFI:DEF-CALL-IN</code></a>) and
 <strong class="first"><em class="firstterm">anonymous foreign functions<a id="dffi-ff-a" class="indexterm"></a></em></strong>; they arise through conversion of function
 pointers using <a class="link" href="#dffi-make-func"><code class="function">FFI:FOREIGN-FUNCTION</code></a>.</p><p>A <strong class="first"><em class="firstterm">call-out function<a id="dffi-ff-call-out" class="indexterm"></a></em></strong> is a foreign function
 called from Lisp: control flow temporarily leaves Lisp.
 A <strong class="first"><em class="firstterm">call-in function<a id="dffi-ff-call-in" class="indexterm"></a></em></strong>
 (AKA <strong class="first"><em class="firstterm">callback<a id="def-call-in-callback-main" class="indexterm"></a></em></strong>)
 is a Lisp function called from the foreign language:
 control flow temporary enters Lisp.</p><p>The following operators define foreign functions:
 </p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="link" href="#def-call-in"><code class="function">FFI:DEF-CALL-IN</code></a></td></tr><tr><td><a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a></td></tr><tr><td><a class="link" href="#dffi-make-func"><code class="function">FFI:FOREIGN-FUNCTION</code></a></td></tr></table><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="dffi-callback-mem"></a>32.3.7.1. Callbacks and memory management</h4></div></div></div><p>Callbacks (<a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> function calling Lisp function) create
 so-called <strong class="first"><em class="firstterm">trampolines<a id="dffi-trampoline" class="indexterm"></a></em></strong>.
 A trampoline is a piece of <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> code which knows how to call a
 particular Lisp function.
 (That is how all foreign language interfaces work, not just ours).
 The <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> pointer that the foreign library receives is the pointer
 to this piece of code.
 These are <span class="strong"><strong>not</strong></span> subject to <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion, as there is no protocol to
 tell the garbage collector when a given callback is not needed anymore
 (unlike with Lisp objects).</p><p>With callbacks to <span class="emphasis"><em>named</em></span> functions (i.e.,
 created by a <a class="link" href="#def-call-in"><code class="function">FFI:DEF-CALL-IN</code></a> form where <em class="replaceable"><code>function</code></em> is a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_f.html#function_name">function name</a>) this is
 mostly harmless, since <em class="replaceable"><code>function</code></em> is unlikely to be redefined.</p><p>With callbacks to <span class="emphasis"><em>anonymous</em></span> functions (i.e.,
 created by <a class="link" href="#dffi-make-func"><code class="function">FFI:FOREIGN-FUNCTION</code></a> or a <a class="link" href="#def-call-in"><code class="function">FFI:DEF-CALL-IN</code></a> form where <em class="replaceable"><code>function</code></em>
 argument is a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-3.html">lambda expression</a>), this might become an issue when they are
 produced dynamically and en masse, e.g. inside a loop, so that many
 trampolines are generated.</p><p>You can use <a class="link" href="#foreign-heap"><code class="function">FFI:FOREIGN-FREE</code></a> to free the trampoline associated with a
 <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a> object, but when you pass a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-3.html">lambda expression</a> to a
 <a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> as an argument of type <a class="link" href="#c-function"><span class="type">FFI:C-FUNCTION</span></a>, such a trampoline
 <span class="strong"><strong>is</strong></span> allocated, but you do <span class="strong"><strong>not</strong></span> get hold of the associated trampoline
 object, and thus you cannot (trivially) free it.
 Thus you may find it easier to create the <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a> object
 first, pass it to the <a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a>, and then call <a class="link" href="#foreign-heap"><code class="function">FFI:FOREIGN-FREE</code></a>
 manually.</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="allocation"></a>32.3.8. Argument and result passing conventions</h3></div></div></div><p>When passed to and from functions, allocation of arguments and
 results is handled as follows:</p><p>Values of <a class="link" href="#simple-c-type"><em class="replaceable"><code>SIMPLE-C-TYPE</code></em></a>, <a class="link" href="#c-pointer"><span class="type">FFI:C-POINTER</span></a> are passed on the stack,
 with dynamic extent. The <a class="link" href="#allocation" title="32.3.8. Argument and result passing conventions"><em class="replaceable"><code>ALLOCATION</code></em></a> is effectively ignored.</p><p>Values of type <a class="link" href="#c-string"><span class="type">FFI:C-STRING</span></a>, <a class="link" href="#c-ptr"><span class="type">FFI:C-PTR</span></a>, <a class="link" href="#c-ptr-null"><span class="type">FFI:C-PTR-NULL</span></a>, <a class="link" href="#c-array-ptr"><span class="type">FFI:C-ARRAY-PTR</span></a>
 need storage.  The <a class="link" href="#allocation" title="32.3.8. Argument and result passing conventions"><em class="replaceable"><code>ALLOCATION</code></em></a> specifies the allocation policy:
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:NONE</code></span></dt><dd>no storage is allocated.
</dd><dt><span class="term"><code class="constant">:ALLOCA</code></span></dt><dd>allocation of storage on the stack, which has
   dynamic extent.</dd><dt><span class="term"><code class="constant">:MALLOC-FREE</code></span></dt><dd>storage will be allocated via <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/malloc.html"><code class="function">malloc</code></a> and released via
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/free.html"><code class="function">free</code></a>.</dd></dl></div><p>If no <a class="link" href="#allocation" title="32.3.8. Argument and result passing conventions"><em class="replaceable"><code>ALLOCATION</code></em></a> is specified, the default <a class="link" href="#allocation" title="32.3.8. Argument and result passing conventions"><em class="replaceable"><code>ALLOCATION</code></em></a> is
 <code class="constant">:NONE</code> for most types, but <code class="constant">:ALLOCA</code> for <a class="link" href="#c-string"><span class="type">FFI:C-STRING</span></a> and <a class="link" href="#c-ptr"><span class="type">FFI:C-PTR</span></a> and
 <a class="link" href="#c-ptr-null"><span class="type">FFI:C-PTR-NULL</span></a> and <a class="link" href="#c-array-ptr"><span class="type">FFI:C-ARRAY-PTR</span></a> and for <code class="constant">:OUT</code> arguments.
 The <code class="constant">:MALLOC-FREE</code> policy provides the ability to pass
 arbitrarily nested structures within a single conversion.</p><p><a id="dffi-allocation-out"></a><strong>Call-out function arguments: </strong></p><div class="variablelist"><dl class="variablelist"><dt><span class="term">For arguments passed from Lisp to <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>:</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:MALLOC-FREE</code></span></dt><dd>Lisp allocates the storage using <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/malloc.html"><code class="function">malloc</code></a> and
     never deallocates it.  The <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> function is supposed to call
     <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/free.html"><code class="function">free</code></a> when done with it.</dd><dt><span class="term"><code class="constant">:ALLOCA</code></span></dt><dd>Lisp allocates the storage on the stack, with
     dynamic extent.  It is freed when the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> function returns.
    </dd><dt><span class="term"><code class="constant">:NONE</code></span></dt><dd><p class="simpara">Lisp assumes that the pointer already points to a
     valid area of the proper size and puts the result value there.</p><p class="simpara">This is dangerous and deprecated.</p></dd></dl></div></dd><dt><span class="term">For results passed from <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> to Lisp:</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:MALLOC-FREE</code></span></dt><dd>Lisp calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/free.html"><code class="function">free</code></a> on it when done.
    </dd><dt><span class="term"><code class="constant">:NONE</code></span></dt><dd>Lisp does nothing.
    </dd></dl></div></dd></dl></div><p><a id="dffi-allocation-in"></a><strong>Call-in function arguments: </strong></p><div class="variablelist"><dl class="variablelist"><dt><span class="term">For arguments passed from <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> to Lisp:</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:MALLOC-FREE</code></span></dt><dd>Lisp calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/free.html"><code class="function">free</code></a> on it when done.
     </dd><dt><span class="term"><code class="constant">:ALLOCA</code><br /></span><span class="term"><code class="constant">:NONE</code></span></dt><dd>Lisp does nothing.
     </dd></dl></div></dd><dt><span class="term">For results passed from Lisp to <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>:</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:MALLOC-FREE</code></span></dt><dd>Lisp allocates the storage using <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/malloc.html"><code class="function">malloc</code></a> and
      never deallocates it.  The <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> function is supposed to call
      <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/free.html"><code class="function">free</code></a> when done with it.</dd><dt><span class="term"><code class="constant">:NONE</code></span></dt><dd><p class="simpara">Lisp assumes that the pointer already points to a
     valid area of the proper size and puts the result value there.</p><p class="simpara">This is dangerous and deprecated.</p></dd></dl></div></dd></dl></div><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="ffi-struct-arg"></a>Warning</h3><p>Passing <a class="link" href="#c-struct"><span class="type">FFI:C-STRUCT</span></a>, <a class="link" href="#c-union"><span class="type">FFI:C-UNION</span></a>,
  <a class="link" href="#c-array"><span class="type">FFI:C-ARRAY</span></a>, <a class="link" href="#c-array-max"><span class="type">FFI:C-ARRAY-MAX</span></a> values as arguments (not via pointers) is
  only possible to the extent the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> compiler supports it.
  Most <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> compilers do it right, but some <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> compilers
  (such as <a class="ulink" href="http://gcc.gnu.org/" target="_top"><span class="command"><strong>gcc</strong></span></a> on <span class="platform">hppa</span>,
  <span class="platform">x86_64</span> and <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>)
  have problems with this.
  The recommended workaround is to pass pointers; this is fully supported.
  See also <a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-devel/">clisp-devel</a>
  (<a class="gmane" href="http://article.gmane.org/gmane.lisp.clisp.devel/10089"><code>Gmane/devel/10089</code></a>/<a class="ulink" href="https://sourceforge.net/p/clisp/mailman/message/12562038/" target="_top">https://sourceforge.net/p/clisp/mailman/message/12562038/</a>).</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="param-mode"></a>32.3.9. Parameter Mode</h3></div></div></div><p>A function parameter's <a class="link" href="#param-mode" title="32.3.9. Parameter Mode"><em class="replaceable"><code>PARAM-MODE</code></em></a> may be</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:IN</code> (means: read-only):</span></dt><dd>The caller passes information to the callee.
  </dd><dt><span class="term"><code class="constant">:OUT</code> (means: write-only):</span></dt><dd>The callee passes information back to the caller on
   return.  When viewed as a Lisp function, there is no Lisp argument
   corresponding to this, instead it means an additional return value.
   Requires <a class="link" href="#allocation" title="32.3.8. Argument and result passing conventions"><em class="replaceable"><code>ALLOCATION</code></em></a> = <code class="constant">:ALLOCA</code>.</dd><dt><span class="term"><code class="constant">:IN-OUT</code> (means: read-write):</span></dt><dd>Information is passed from the caller to the callee
   and then back to the caller.  When viewed as a Lisp function, the
   <code class="constant">:OUT</code> value is returned as an additional return value.
  </dd></dl></div><p>The default is <code class="constant">:IN</code>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="dffi-examples"></a>32.3.10. Examples</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#dffi-ex-more">32.3.10.1. More examples</a></span></dt></dl></div><div class="list-of-examples"><p><strong>List of Examples</strong></p><dl><dt>32.2. <a href="#dffi-simple">Simple declarations and access</a></dt><dt>32.3. <a href="#dffi-extern-var">External <span class="command"><strong>C</strong></span> variable and some accesses</a></dt><dt>32.4. <a href="#dffi-extern-func1">Calling an external function</a></dt><dt>32.5. <a href="#dffi-extern-func2">Another example for calling an external function</a></dt><dt>32.6. <a href="#dffi-ex-macro">Accessing <span class="command"><strong>cpp</strong></span> macros</a></dt><dt>32.7. <a href="#ex-call-in">Calling Lisp from <span class="command"><strong>C</strong></span></a></dt><dt>32.8. <a href="#ex-call-in-dll">Calling Lisp from <span class="command"><strong>C</strong></span> dynamically</a></dt><dt>32.9. <a href="#dffi-gethostname">Variable size arguments:   calling <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/gethostname.html"><code class="function">gethostname</code></a> from <span class="command"><strong>CLISP</strong></span></a></dt><dt>32.10. <a href="#dffi-dll-var">Accessing variables in shared libraries</a></dt><dt>32.11. <a href="#ex-dffi-validity">Controlling validity of resources</a></dt><dt>32.12. <a href="#ex-dffi-float">Floating point arrays</a></dt></dl></div><div class="example"><a id="dffi-simple"></a><p class="title"><strong>Example 32.2. Simple declarations and access</strong></p><div class="example-contents"><p>The <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> declaration </p><pre class="programlisting">
struct foo {
  int a;
  struct foo * b[100];
};
</pre><p> corresponds to </p><pre class="programlisting">
(<a class="link" href="#def-c-struct"><code class="function">FFI:DEF-C-STRUCT</code></a> foo
  (a int)
  (b (c-array (c-ptr foo) 100)))
</pre><p>The element access </p><pre class="programlisting">
struct foo f;
f.b[7].a
</pre><p> corresponds to </p><pre class="programlisting">
(declare (type foo f))
(foo-a (aref (foo-b f) 7)) <strong>	; </strong><em class="lineannotation"><span class="lineannotation">or</span></em>
(slot-value (aref (slot-value f 'b) 7) 'a)
</pre></div></div><br class="example-break" /><div class="example"><a id="dffi-extern-var"></a><p class="title"><strong>Example 32.3. External <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> variable and some accesses</strong></p><div class="example-contents"><pre class="programlisting">
struct bar {
  short x, y;
  char a, b;
  int z;
  struct bar * n;
};

extern struct bar * my_struct;

my_struct-&gt;x++;
my_struct-&gt;a = 5;
my_struct = my_struct-&gt;n;
</pre><p> corresponds to </p><pre class="programlisting">
(<a class="link" href="#def-c-struct"><code class="function">FFI:DEF-C-STRUCT</code></a> bar
  (x short)
  (y short)
  (a char)
  (b char) <strong>	; </strong><em class="lineannotation"><span class="lineannotation">or (b character) if it represents a character, not a number</span></em>
  (z int)
  (n (c-ptr bar)))

(<a class="link" href="#def-c-var"><code class="function">FFI:DEF-C-VAR</code></a> my_struct (:type (c-ptr bar)))

(setq my_struct (let ((s my_struct)) (incf (slot-value s 'x)) s)) <strong>	; </strong><em class="lineannotation"><span class="lineannotation">or</span></em>
(incf (slot my_struct 'x))
(setq my_struct (let ((s my_struct)) (setf (slot-value s 'a) 5) s)) <strong>	; </strong><em class="lineannotation"><span class="lineannotation">or</span></em>
(setf (slot my_struct 'a) 5)
(setq my_struct (slot-value my_struct 'n)) <strong>	; </strong><em class="lineannotation"><span class="lineannotation">or</span></em>
(setq my_struct (deref (slot my_struct 'n)))
</pre></div></div><br class="example-break" /><div class="example"><a id="dffi-extern-func1"></a><p class="title"><strong>Example 32.4. Calling an external function</strong></p><div class="example-contents"><p>On <a class="ulink" href="http://www.ansi.org/" target="_top"><acronym class="acronym" title="The American National Standards Institute">ANSI</acronym></a> <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> systems, <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/stdlib.h.html">&lt;<code class="filename">stdlib.h</code>&gt;</a>
 contains the declarations:

</p><pre class="programlisting">
typedef struct {
  int quot;   /* Quotient */
  int rem;    /* Remainder */
} div_t;
extern div_t div (int numer, int denom);
</pre><p>

This translates to

</p><pre class="programlisting">
(<a class="link" href="#def-c-struct"><code class="function">FFI:DEF-C-STRUCT</code></a> (div_t :typedef)
  (quot int)
  (rem int))
(<a class="link" href="#c-flavor" title="32.3.4. The choice of the C flavor"><code class="function">FFI:DEFAULT-FOREIGN-LANGUAGE</code></a> :stdc)
(<a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> div (<code class="constant">:ARGUMENTS</code> (numer int) (denom int))
  (<code class="constant">:RETURN-TYPE</code> div_t))
</pre><p>
Sample call from within Lisp (after running <span class="command"><strong><a href="clisp-link.html#clisp-link" class="olink">clisp-link</a></strong></span>):
</p><pre class="programlisting">
(div 20 3)
⇒ <code class="computeroutput">#S(DIV_T :QUOT 6 :REM 2)</code>
</pre></div></div><br class="example-break" /><div class="example"><a id="dffi-extern-func2"></a><p class="title"><strong>Example 32.5. Another example for calling an external function</strong></p><div class="example-contents"><p>Suppose the following is defined in a file <code class="filename">cfun.c</code>:
</p><pre class="programlisting">
struct cfunr { int x; char *s; };
struct cfunr * cfun (int i,char *s,struct cfunr * r,int a[10]) {
  int j;
  struct cfunr * r2;
  printf("i = %d\n", i);
  printf("s = %s\n", s);
  printf("r-&gt;x = %d\n", r-&gt;x);
  printf("r-&gt;s = %s\n", r-&gt;s);
  for (j = 0; j &lt; 10; j++) printf("a[%d] = %d.\n", j, a[j]);
  r2 = (struct cfunr *) malloc (sizeof (struct cfunr));
  r2-&gt;x = i+5;
  r2-&gt;s = "A C string";
  return r2;
}
</pre><p>

It is possible to call this function from Lisp using the file
<code class="filename">callcfun.lisp</code> (do not call it
<code class="filename">cfun.lisp</code> - <a href="impnotes.html#compilefile" class="olink"><code class="function">COMPILE-FILE</code></a> will
<a class="link" href="#c-file-overwrite" title="Warning">overwrite</a>
<code class="filename">cfun.c</code>) whose contents is:

</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defpackage.html" target="_top"><code class="function">DEFPACKAGE</code></a> "TEST-C-CALL" (:use <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong></a> <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>))
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_in-package.html" target="_top"><code class="function">IN-PACKAGE</code></a> "TEST-C-CALL")
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_eval-when.html" target="_top"><code class="function">EVAL-WHEN</code></a> (compile) (setq <a class="link" href="#ffi-extern-output"><code class="varname">FFI:*OUTPUT-C-FUNCTIONS*</code></a> t))
(<a class="link" href="#def-c-struct"><code class="function">FFI:DEF-C-STRUCT</code></a> cfunr (x int) (s c-string))
(<a class="link" href="#c-flavor" title="32.3.4. The choice of the C flavor"><code class="function">FFI:DEFAULT-FOREIGN-LANGUAGE</code></a> :stdc)
(<a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> cfun (<code class="constant">:RETURN-TYPE</code> (c-ptr cfunr))
  (<code class="constant">:ARGUMENTS</code> (i int)
              (s c-string)
              (r (c-ptr cfunr) :in :alloca)
              (a (c-ptr (c-array int 10)) :in :alloca)))
(defun call-cfun ()
  (cfun 5 "A Lisp string" (make-cfunr :x 10 :s "Another Lisp string")
        '#(0 1 2 3 4 5 6 7 8 9)))
</pre><p>

Use the <a href="impnotes.html#modules" class="olink">module</a> facility:

</p><pre class="screen">
<strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp-link.html#clisp-link" class="olink">clisp-link</a></strong></span> create cfun callcfun.c
<strong><code class="prompt">$</code></strong> cc -O -c cfun.c
<strong><code class="prompt">$</code></strong> cd cfun
<strong><code class="prompt">$</code></strong> ln -s ../cfun.o cfun.o
Add cfun.o to NEW_LIBS and NEW_FILES in <a href="impnotes.html#modset" class="olink"><span class="command"><strong>link.sh</strong></span></a>.
<strong><code class="prompt">$</code></strong> cd ..
<strong><code class="prompt">$</code></strong> base/lisp.run <code class="option"><a href="clisp.html#opt-memfile" class="olink">-M</a></code> base/lispinit.mem <code class="option"><a href="clisp.html#opt-compile" class="olink">-c</a></code> callcfun.lisp
<strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp-link.html#clisp-link" class="olink">clisp-link</a></strong></span> add base base+cfun cfun
<strong><code class="prompt">$</code></strong> base+cfun/lisp.run <code class="option"><a href="clisp.html#opt-memfile" class="olink">-M</a></code> base+cfun/lispinit.mem <code class="option"><a href="clisp.html#opt-init" class="olink">-i</a></code> callcfun
&gt; (test-c-call::call-cfun)
i = 5
s = A Lisp string
r-&gt;x = 10
r-&gt;s = Another Lisp string
a[0] = 0.
a[1] = 1.
a[2] = 2.
a[3] = 3.
a[4] = 4.
a[5] = 5.
a[6] = 6.
a[7] = 7.
a[8] = 8.
a[9] = 9.
#S(TEST-C-CALL::CFUNR :X 10 :S "A C string")
&gt;
<strong><code class="prompt">$</code></strong> rm -r base+cfun</pre><p>Note that there is a memory leak here: The return value
<code class="varname">r2</code> of <code class="function">cfun()</code> is
<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/malloc.html"><code class="function">malloc</code></a>ed but never <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/free.html"><code class="function">free</code></a>d. Specifying</p><pre class="programlisting">
(<code class="constant">:RETURN-TYPE</code> (c-ptr cfunr) :malloc-free)
</pre><p>
is not an alternative because this would also
<code class="function">free(r2-&gt;x)</code> but <code class="varname">r2-&gt;x</code> is a
pointer to static data.</p><p>The memory leak can be avoided using
</p><pre class="programlisting">
(<code class="constant">:RETURN-TYPE</code> (c-pointer cfunr))
</pre><p>
instead, in conjunction with
</p><pre class="programlisting">
(defun call-cfun ()
  (let ((data (cfun ...)))
    (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_unwind-protect.html" target="_top"><code class="function">UNWIND-PROTECT</code></a> (<a class="link" href="#foreign-value"><code class="function">FFI:FOREIGN-VALUE</code></a> data)
      (<a class="link" href="#foreign-heap"><code class="function">FFI:FOREIGN-FREE</code></a> data :FULL nil))))
</pre></div></div><br class="example-break" /><div class="example"><a id="dffi-ex-macro"></a><p class="title"><strong>Example 32.6. Accessing <a class="ulink" href="http://gcc.gnu.org/onlinedocs/cpp/" target="_top"><span class="command"><strong>cpp</strong></span></a> macros</strong></p><div class="example-contents"><p>Suppose you are interfacing to a library <code class="filename">mylib.so</code>
 which defines types, macros and <code class="literal">inline</code> functions
 in <code class="filename">mylib.h</code>:</p><pre class="programlisting">
#define FOO(x)  .....
#define BAR ...
struct zot { ... }
inline int bar (int x) { ... }
</pre><p>
 To make them available from <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>, write these forms into the lisp
 file <code class="filename">my.lisp</code>:</p><pre class="programlisting">
(<a class="link" href="#c-lines"><code class="function">FFI:C-LINES</code></a> "#include &lt;mylib.h&gt;
int my_foo (int x) { return FOO(x); }
int my_bar (int x) { return bar(x); }~%")
(<a class="link" href="#def-c-const"><code class="function">FFI:DEF-C-CONST</code></a> bar)
(<a class="link" href="#def-c-const"><code class="function">FFI:DEF-C-CONST</code></a> zot-size (:name "sizeof(struct zot)") (:guard nil))
(<a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> my-foo (<code class="constant">:NAME</code> "my_foo") (<code class="constant">:ARGUMENTS</code> (x ffi:int)) (<code class="constant">:RETURN-TYPE</code> ffi:int))
(<a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> my-bar (<code class="constant">:NAME</code> "my_bar") (<code class="constant">:ARGUMENTS</code> (x ffi:int)) (<code class="constant">:RETURN-TYPE</code> ffi:int))
</pre><p>Compiling this file will produce <code class="filename">my.c</code>
 and <code class="filename">my.fas</code> and you have two options:
 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Compile <code class="filename">my.c</code>
    into <code class="filename">my.o</code> with
    </p><pre class="screen"><strong><code class="prompt">$</code></strong> gcc -c my.c -lmylib</pre><p>
    and use <span class="command"><strong><a href="clisp-link.html#clisp-link" class="olink">clisp-link</a></strong></span> to create a new <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a href="impnotes.html#linkset" class="olink">linking set</a>.
  </p></li><li class="listitem"><p>Add <code class="code">(<code class="constant">:LIBRARY</code> "my.dll")</code> to the <a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a>
    forms, compile <code class="filename">my.c</code> into <code class="filename">my.so</code>
    (or <code class="filename">my.dll</code> on <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>) with
    </p><pre class="screen"><strong><code class="prompt">$</code></strong> gcc -shared -o my.so my.c -lmylib</pre><p> and
    load <code class="filename">my.fas</code>.</p></li></ol></div><p>Of course, you could have created <code class="filename">my1.c</code>
 containing</p><pre class="programlisting">
#include &lt;mylib.h&gt;
int my_foo (int x) { return FOO(x); }
int my_bar (int x) { return bar(x); }
</pre><p>manually, but <a class="link" href="#c-lines"><code class="function">FFI:C-LINES</code></a> allows you to keep the
 definitions of <code class="function">my_foo</code> and <code class="function">my-foo</code>
 close together for easier maintenance.</p></div></div><br class="example-break" /><div class="example"><a id="ex-call-in"></a><p class="title"><strong>Example 32.7. Calling Lisp from <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a></strong></p><div class="example-contents"><p>To sort an array of double-floats using the Lisp function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_sortcm_stable-sort.html" target="_top"><code class="function">SORT</code></a>
 instead of the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> library function
 <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/qsort.html"><code class="function">qsort</code></a>, one can use the
 following interface code <code class="filename">sort1.c</code>.
 The main problem is to pass a variable-sized array.

</p><pre class="programlisting">
extern void lispsort_begin (int);
void* lispsort_function;
void lispsort_double (int n, double * array) {
  double * sorted_array;
  int i;
  lispsort_begin(n); /* store #'sort2 in lispsort_function */
  sorted_array = ((double * (*) (double *)) lispsort_function) (array);
  for (i = 0; i &lt; n; i++) array[i] = sorted_array[i];
  free(sorted_array);
}
</pre><p>

This is accompanied by <code class="filename">sort2.lisp</code>:

</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defpackage.html" target="_top"><code class="function">DEFPACKAGE</code></a> "FFI-TEST" (:use <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong></a> <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>))
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_in-package.html" target="_top"><code class="function">IN-PACKAGE</code></a> "FFI-TEST")
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_eval-when.html" target="_top"><code class="function">EVAL-WHEN</code></a> (compile) (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/spefor_setq.html" target="_top"><code class="function">SETQ</code></a> <a class="link" href="#ffi-extern-output"><code class="varname">FFI:*OUTPUT-C-FUNCTIONS*</code></a> t))
(<a class="link" href="#def-call-in"><code class="function">FFI:DEF-CALL-IN</code></a> lispsort_begin (<code class="constant">:ARGUMENTS</code> (n int))
  (<code class="constant">:RETURN-TYPE</code> nil)
  (<a class="link" href="#c-flavor" title="32.3.4. The choice of the C flavor"><code class="constant">:LANGUAGE</code></a> :stdc))
(<a class="link" href="#def-c-var"><code class="function">FFI:DEF-C-VAR</code></a> lispsort_function (:type c-pointer))
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defun.html" target="_top"><code class="function">DEFUN</code></a> lispsort_begin (n)
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="link" href="#cast"><code class="function">FFI:CAST</code></a> lispsort_function
              `(<a class="link" href="#c-function"><span class="type">FFI:C-FUNCTION</span></a>
                 (<code class="constant">:ARGUMENTS</code> (v (c-ptr (c-array double-float ,n))))
                 (<code class="constant">:RETURN-TYPE</code> (c-ptr (c-array double-float ,n))
                               :malloc-free)))
        #'sort2))
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defun.html" target="_top"><code class="function">DEFUN</code></a> sort2 (v)
  (declare (type vector v))
  (sort v #'&lt;))
</pre><p>

To test this, use the following test file <code class="filename">sorttest.lisp</code>:

</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_eval-when.html" target="_top"><code class="function">EVAL-WHEN</code></a> (compile) (setq <a class="link" href="#ffi-extern-output"><code class="varname">FFI:*OUTPUT-C-FUNCTIONS*</code></a> t))
(<a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> sort10
  (<code class="constant">:NAME</code> "lispsort_double")
  (<a class="link" href="#c-flavor" title="32.3.4. The choice of the C flavor"><code class="constant">:LANGUAGE</code></a> :stdc)
  (<code class="constant">:ARGUMENTS</code> (n ffi:int)
              (array (<a class="link" href="#c-ptr"><span class="type">FFI:C-PTR</span></a> (<a class="link" href="#c-array"><span class="type">FFI:C-ARRAY</span></a> ffi:double-float 10)) :in-out)))
</pre><p>

Now try

</p><pre class="screen"><strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp-link.html#clisp-link" class="olink">clisp-link</a></strong></span> create sort sort2.c sorttest.c
<strong><code class="prompt">$</code></strong> cc -O -c sort1.c
<strong><code class="prompt">$</code></strong> cd sort
<strong><code class="prompt">$</code></strong> ln -s ../sort1.o sort1.o</pre><p>

Add <code class="filename">sort1.o</code> to <code class="envar">NEW_LIBS</code>
and <code class="envar">NEW_FILES</code> in <a href="impnotes.html#modset" class="olink"><span class="command"><strong>link.sh</strong></span></a>.
Create a file <code class="filename">package.lisp</code> containing the form
</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-package.html" target="_top"><code class="function">MAKE-PACKAGE</code></a> "FFI-TEST" :use '(<a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_11-1-2-1.html"><strong class="package"><span class="quote">“<span class="quote">COMMON-LISP</span>”</span></strong></a> <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>))</pre><p>
and add <code class="filename">package.lisp</code> to <a class="link" href="#mod-preload"><code class="envar">TO_PRELOAD</code></a> in <a href="impnotes.html#modset" class="olink"><span class="command"><strong>link.sh</strong></span></a>.
Proceed:

</p><pre class="screen"><strong><code class="prompt">$</code></strong> cd ..
<strong><code class="prompt">$</code></strong> base/lisp.run <code class="option"><a href="clisp.html#opt-memfile" class="olink">-M</a></code> base/lispinit.mem <code class="option"><a href="clisp.html#opt-compile" class="olink">-c</a></code> sort2.lisp <code class="option"><a href="clisp.html#opt-compile" class="olink">-c</a></code> sorttest.lisp
<strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp-link.html#clisp-link" class="olink">clisp-link</a></strong></span> add base base+sort sort
<strong><code class="prompt">$</code></strong> base+sort/lisp.run <code class="option"><a href="clisp.html#opt-memfile" class="olink">-M</a></code> base+sort/lispinit.mem <code class="option"><a href="clisp.html#opt-init" class="olink">-i</a></code> sort2 sorttest
&gt; (sort10 10 '#(0.501d0 0.528d0 0.615d0 0.550d0 0.711d0
                0.523d0 0.585d0 0.670d0 0.271d0 0.063d0))
#(0.063d0 0.271d0 0.501d0 0.523d0 0.528d0 0.55d0 0.585d0 0.615d0 0.67d0 0.711d0)
<strong><code class="prompt">$</code></strong> rm -r base+sort</pre></div></div><br class="example-break" /><div class="example"><a id="ex-call-in-dll"></a><p class="title"><strong>Example 32.8. Calling Lisp from <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> dynamically</strong></p><div class="example-contents"><p>Create a dynamic library <code class="filename">lispdll</code>
 (<code class="filename">#P".dll"</code> on <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>,
  <code class="filename">#P".so"</code> on <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>)
  with the following function:</p><pre class="programlisting">
typedef int (*LispFunc)(int parameter);
int CallInFunc(LispFunc f) {
  return f(5)+11;
}
</pre><p>
  and call it from Lisp:
  </p><pre class="programlisting">
(ffi:def-call-out callout
  (<code class="constant">:NAME</code> "CallInFunc")
  (<code class="constant">:LIBRARY</code> "lispdll.dll")
  (<code class="constant">:ARGUMENTS</code> (function-arg
               (<a class="link" href="#c-function"><span class="type">FFI:C-FUNCTION</span></a> (<code class="constant">:ARGUMENTS</code> (number ffi:int))
                               (<code class="constant">:RETURN-TYPE</code> ffi:int) (<a class="link" href="#c-flavor" title="32.3.4. The choice of the C flavor"><code class="constant">:LANGUAGE</code></a> :stdc))))
  (<code class="constant">:RETURN-TYPE</code> ffi:int)
  (<a class="link" href="#c-flavor" title="32.3.4. The choice of the C flavor"><code class="constant">:LANGUAGE</code></a> :stdc))
(defun f (x) (* x 2))
⇒ <code class="computeroutput">F</code>
(callout #'f)
⇒ <code class="computeroutput">21</code>
</pre></div></div><br class="example-break" /><div class="example"><a id="dffi-gethostname"></a><p class="title"><strong>Example 32.9. Variable size arguments:
  calling <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/gethostname.html"><code class="function">gethostname</code></a> from <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a></strong></p><div class="example-contents"><p>The standard <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> function
 </p><div class="funcsynopsis"><a id="gethostname-synopsis"></a><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <strong class="fsfunc">gethostname</strong>(</code></td><td>char* <var class="pdparam">name</var>, </td></tr><tr><td> </td><td>size_t <var class="pdparam">length</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div><p>
 follows a typical pattern of <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> <span class="quote">“<span class="quote">out</span>”</span>-parameter
 convention: it expects a pointer to a buffer it is going to fill.
 So you must view this parameter as either <code class="constant">:OUT</code> or <code class="constant">:IN-OUT</code>.
 Additionally, one must tell the function the size of the buffer.
 Here <em class="replaceable"><code>length</code></em> is just an <code class="constant">:IN</code> parameter.
 Sometimes this will be an <code class="constant">:IN-OUT</code> parameter, returning the
 number of bytes actually filled in.</p><p>So <em class="replaceable"><code>name</code></em> is actually a pointer to an array of up to <em class="replaceable"><code>length</code></em>
 characters, regardless of what the poor <span class="type">char*</span> <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>
 prototype says, to be used like a <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> <span class="type">string</span>
 (<code class="constant">NULL</code>-termination).  <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> specifies that <span class="quote">“<span class="quote">host names are
 limited to <code class="constant">HOST_NAME_MAX</code> bytes</span>”</span>, which is,
 of course, system dependent, but it appears that 256 is sufficient.</p><p>In the present example, you can use allocation <code class="constant">:ALLOCA</code>, like
 you would do in <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>: stack-allocate a temporary:
</p><pre class="programlisting">
(<a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> gethostname
  (<code class="constant">:ARGUMENTS</code> (name (<a class="link" href="#c-ptr"><span class="type">FFI:C-PTR</span></a> (<a class="link" href="#c-array-max"><span class="type">FFI:C-ARRAY-MAX</span></a> ffi:char 256))
                    <code class="constant">:OUT</code> <code class="constant">:ALLOCA</code>)
              (length ffi:int))
  (<a class="link" href="#c-flavor" title="32.3.4. The choice of the C flavor"><code class="constant">:LANGUAGE</code></a> :stdc) (<code class="constant">:LIBRARY</code> :default)
  (<code class="constant">:RETURN-TYPE</code> ffi:int))
⇒ <code class="computeroutput">GETHOSTNAME</code>
(defun myhostname ()
  (multiple-value-bind (success name)<strong>	; </strong><em class="lineannotation"><span class="lineannotation"><code class="constant">:OUT</code> and <code class="constant">:IN-OUT</code> parameters are returned as <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_m.html#multiple_values">multiple values</a></span></em>
      (gethostname 256)
    (if (zerop success) name
      (error "~S: ~S: ~S" 'myhostname (os:errno) (os:strerror)))))<strong>	; </strong><em class="lineannotation"><span class="lineannotation">See <a class="xref" href="#errno" title="33.2.15. Error handling">Section 33.2.15, “Error handling”</a></span></em>
⇒ <code class="computeroutput">MYHOSTNAME</code>
(myhostname)
⇒ <code class="computeroutput">#(97 98 97 122 111 110 107)</code></pre><p>
It is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-vector.html" target="_top"><code class="classname">SIMPLE-VECTOR</code></a>, not a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>, because the <em class="replaceable"><code>name</code></em>
argument is an array of <span class="type">char</span> (an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> type, see
<a class="xref" href="#dffi-types" title="32.3.3. (Foreign) C types">Section 32.3.3, “(Foreign) <span class="command"><strong>C</strong></span> types”</a>), <span class="strong"><strong>not</strong></span> <span class="type">character</span>.
</p><pre class="programlisting">
(<a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> gethostname
  (<code class="constant">:ARGUMENTS</code> (name (<a class="link" href="#c-ptr"><span class="type">FFI:C-PTR</span></a> (<a class="link" href="#c-array-max"><span class="type">FFI:C-ARRAY-MAX</span></a> character 256))
                    <code class="constant">:OUT</code> <code class="constant">:ALLOCA</code>)
              (length ffi:int))
  (<a class="link" href="#c-flavor" title="32.3.4. The choice of the C flavor"><code class="constant">:LANGUAGE</code></a> :stdc) (<code class="constant">:LIBRARY</code> :default)
  (<code class="constant">:RETURN-TYPE</code> ffi:int))
⇒ <code class="computeroutput">GETHOSTNAME</code>
(myhostname)
⇒ <code class="computeroutput">"abazonk"</code></pre><p>
Now we have a different problem:
if <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/gethostname.html"><code class="function">gethostname</code></a> fails, then the buffer
allocated for <em class="replaceable"><code>name</code></em> will be filled with garbage, but it will still go
through the string conversion <span class="strong"><strong>before</strong></span> we can check
the <em class="replaceable"><code>success</code></em> status.
If <a href="impnotes.html#foreign-enc" class="olink"><code class="varname">CUSTOM:*FOREIGN-ENCODING*</code></a> is <a class="link" href="#charset-UTF-16"><code class="constant">CHARSET:ISO-8859-1</code></a>, this is not a problem since no real
conversion is happening, but with <a class="link" href="#charset-UTF-8"><code class="constant">CHARSET:UTF-8</code></a> an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> may be <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.
A safe approach is to pass to the foreign function our own
stack-allocated buffer, and only convert the buffer to a string when the
foreign function succeeds: </p><pre class="programlisting">
(<a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> gethostname
  (<code class="constant">:ARGUMENTS</code> (name <a class="link" href="#c-pointer"><span class="type">FFI:C-POINTER</span></a>)
              (length ffi:int))
  (<a class="link" href="#c-flavor" title="32.3.4. The choice of the C flavor"><code class="constant">:LANGUAGE</code></a> :stdc) (<code class="constant">:LIBRARY</code> :default)
  (<code class="constant">:RETURN-TYPE</code> ffi:int))
⇒ <code class="computeroutput">GETHOSTNAME</code>
(defun myhostname ()
  (<a class="link" href="#foreign-stack"><code class="function">FFI:WITH-FOREIGN-OBJECT</code></a> (name '(<a class="link" href="#c-array-max"><span class="type">FFI:C-ARRAY-MAX</span></a> character 256))
    (let ((success (gethostname name 256)))
      (if (zerop success) (<a class="link" href="#foreign-value"><code class="function">FFI:FOREIGN-VALUE</code></a> name)
        (error "~S: ~S: ~S" 'myhostname (os:errno) (os:strerror))))))
⇒ <code class="computeroutput">MYHOSTNAME</code>
(myhostname)
⇒ <code class="computeroutput">"abazonk"</code></pre><p>
Note that the <em class="replaceable"><code>type</code></em> argument of <a class="link" href="#foreign-stack"><code class="function">FFI:WITH-FOREIGN-OBJECT</code></a> is evaluated,
so we do not have to make any assumptions
about <code class="constant">HOST_NAME_MAX</code>: </p><pre class="programlisting">
(defun myhostname ()
  (let ((host-name-max (<a class="link" href="#sysinfo" title="33.2.4. System Information">os:sysconf</a> :host-name-max)))
    (<a class="link" href="#foreign-stack"><code class="function">FFI:WITH-FOREIGN-OBJECT</code></a> (name `(<a class="link" href="#c-array-max"><span class="type">FFI:C-ARRAY-MAX</span></a> character ,host-name-max))
      (let ((success (gethostname name host-name-max)))
        (if (zerop success) (<a class="link" href="#foreign-value"><code class="function">FFI:FOREIGN-VALUE</code></a> name)
          (error "~S: ~S: ~S" 'myhostname (os:errno) (os:strerror)))))))
⇒ <code class="computeroutput">MYHOSTNAME</code>
(myhostname)
⇒ <code class="computeroutput">"abazonk"</code></pre><p>
</p></div></div><br class="example-break" /><div class="example"><a id="dffi-dll-var"></a><p class="title"><strong>Example 32.10. Accessing variables in shared libraries</strong></p><div class="example-contents"><p>Suppose one wants to access and modify variables that reside in
 shared libraries:
</p><pre class="programlisting">
struct bar {
  double x, y;
  double out;
};

struct bar my_struct = {10.0, 20.5, 0.0};

double test_dll(struct bar *ptr)
{
  return ptr-&gt;out = ptr-&gt;out + ptr-&gt;x + ptr-&gt;y;
}
</pre><p>This is compiled to <code class="filename">libtest.so</code> (or
 <code class="filename">libtest.dll</code>, depending on your platform).</p><p>Use the following lisp code:
</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_use-package.html" target="_top"><code class="function">USE-PACKAGE</code></a> <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>)

(<a class="link" href="#def-c-struct"><code class="function">FFI:DEF-C-STRUCT</code></a> bar
  (x double-float)
  (y double-float)
  (out double-float))

(<a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> get-own-c-float
  (<code class="constant">:LIBRARY</code> "libtest.so")
  (<a class="link" href="#c-flavor" title="32.3.4. The choice of the C flavor"><code class="constant">:LANGUAGE</code></a> :stdc)
  (<code class="constant">:NAME</code> "test_dll")
  (<code class="constant">:ARGUMENTS</code> (ptr c-pointer :in :alloca))
  (<code class="constant">:RETURN-TYPE</code> double-float))

(<a class="link" href="#def-c-var"><code class="function">FFI:DEF-C-VAR</code></a> my-c-var (:name "my_struct")
  (<code class="constant">:LIBRARY</code> "libtest.so") (:type (c-ptr bar)))
</pre><p>Note that <code class="function">get-own-c-float</code> takes a
 <a class="link" href="#c-pointer"><span class="type">FFI:C-POINTER</span></a>, not a <span class="type"><code class="literal">(<a class="link" href="#c-ptr"><span class="type">FFI:C-PTR</span></a> bar)</code></span> as the
 argument.</p><p>Now you can access call <code class="function">get-own-c-float</code> on
<code class="varname">my-c-var</code>:
</p><pre class="programlisting">
(<a class="link" href="#c-var-addr"><code class="function">FFI:C-VAR-ADDRESS</code></a> my-c-var)
⇒ <code class="computeroutput">#&lt;FOREIGN-ADDRESS #x282935D8&gt;</code>
(get-own-c-float (<a class="link" href="#c-var-addr"><code class="function">FFI:C-VAR-ADDRESS</code></a> my-c-var))
⇒ <code class="computeroutput">30.5d0</code>
(get-own-c-float (<a class="link" href="#c-var-addr"><code class="function">FFI:C-VAR-ADDRESS</code></a> my-c-var))
⇒ <code class="computeroutput">61.0d0</code>
(get-own-c-float (<a class="link" href="#c-var-addr"><code class="function">FFI:C-VAR-ADDRESS</code></a> my-c-var))
⇒ <code class="computeroutput">91.5d0</code>
(get-own-c-float (<a class="link" href="#c-var-addr"><code class="function">FFI:C-VAR-ADDRESS</code></a> my-c-var))
⇒ <code class="computeroutput">122.0d0</code>
</pre></div></div><br class="example-break" /><div class="example"><a id="ex-dffi-validity"></a><p class="title"><strong>Example 32.11. Controlling validity of resources</strong></p><div class="example-contents"><p><a class="link" href="#fptr"><code class="function">FFI:SET-FOREIGN-POINTER</code></a> is useful in conjunction with <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>
  <a class="link" href="#validp"><code class="function">FFI:VALIDP</code></a>)</code> to limit the extent of external resources.
 Closing twice can be avoided by checking <a class="link" href="#validp"><code class="function">FFI:VALIDP</code></a>.
 All pointers depending on this resource can be disabled at once upon
 close by sharing their <a class="link" href="#fptr"><code class="function">FFI:FOREIGN-POINTER</code></a> using <a class="link" href="#fptr"><code class="function">FFI:SET-FOREIGN-POINTER</code></a>.
</p><pre class="programlisting">
(<a class="link" href="#def-c-type"><code class="function">FFI:DEF-C-TYPE</code></a> PGconn c-pointer)<strong>	; </strong><em class="lineannotation"><span class="lineannotation">opaque pointer</span></em>
(<a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> PQconnectdb (<code class="constant">:RETURN-TYPE</code> PGconn)
  (<code class="constant">:ARGUMENTS</code> (conninfo c-string)))
(defun sql-connect (conninfo)
  (let ((conn (PQconnectdb conninfo)))
    (unless conn (error "NULL pointer"))
    ;; may wish to use <a class="link" href="#final" title="31.8. Finalization"><code class="function">EXT:FINALIZE</code></a> as well
    (<a class="link" href="#fptr"><code class="function">FFI:SET-FOREIGN-POINTER</code></a> conn <code class="constant">:COPY</code>)))
(defun sql-dependent-resource (conn arg1)
  (<a class="link" href="#fptr"><code class="function">FFI:SET-FOREIGN-POINTER</code></a> (PQxxx conn arg1) conn))
(defun sql-close (connection)
  (when (<a class="link" href="#validp"><code class="function">FFI:VALIDP</code></a> connection)
    (PQfinish connection)
    (setf (<a class="link" href="#validp"><code class="function">FFI:VALIDP</code></a> connection) nil)
    T))
</pre><p>
</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>Sharing <a class="link" href="#fptr"><code class="function">FFI:FOREIGN-POINTER</code></a> goes both ways: invalidating
  the dependent resource will invalidate the primary one.</p></div><p>
</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>An alternative approach to resource management,
  more suitable to non-<a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> <a href="impnotes.html#modules" class="olink">module</a>s,
  is implemented in the <span class="module"><a class="filename" href="#berkeley-db" title="33.7. Berkeley DB access"><code class="filename">berkeley-db</code></a></span> module,
  see <a class="xref" href="#bdb-close" title="33.7.2. Closing handles">Section 33.7.2, “Closing handles”</a>.</p></div></div></div><br class="example-break" /><div class="example"><a id="ex-dffi-float"></a><p class="title"><strong>Example 32.12. Floating point arrays</strong></p><div class="example-contents"><p>Save this code into <code class="filename">sum.c</code>:
</p><pre class="programlisting">
double sum (int len, double *vec) {
  int i;
  double s=0;
  for (i=0; i&lt;len; i++) s+= vec[i];
  return s;
}
</pre><p>
and compile it with
</p><pre class="screen"><strong><code class="prompt">$</code></strong> gcc -shared -o libsum.so sum.c</pre><p>
Now you can sum doubles:
</p><pre class="programlisting">
(<a class="link" href="#def-call-out"><code class="function">FFI:DEF-CALL-OUT</code></a> sum (<code class="constant">:NAME</code> "sum") (<code class="constant">:LIBRARY</code> "libsum.so") (<a class="link" href="#c-flavor" title="32.3.4. The choice of the C flavor"><code class="constant">:LANGUAGE</code></a> :stdc)
  (<code class="constant">:RETURN-TYPE</code> ffi:double-float)
  (<code class="constant">:ARGUMENTS</code> (len ffi:int) (vec (<a class="link" href="#c-array-ptr"><span class="type">FFI:C-ARRAY-PTR</span></a> ffi:double-float))))
(sum 3 #(1d0 2d0 3d0))
⇒ <code class="computeroutput">6d0</code>
</pre></div></div><br class="example-break" /><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="dffi-ex-more"></a>32.3.10.1. More examples</h4></div></div></div><p>You can find more information and examples of the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
 <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> in the following <a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-list/">clisp-list</a> messages:
 </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">variable size values</span></dt><dd><a class="gmane" href="http://article.gmane.org/gmane.lisp.clisp.general/7278"><code>Gmane/general/7278</code></a>/<a class="ulink" href="https://sourceforge.net/p/clisp/mailman/message/10143425/" target="_top">https://sourceforge.net/p/clisp/mailman/message/10143425/</a>
  </dd><dt><span class="term">variable length arrays</span></dt><dd><a class="gmane" href="http://article.gmane.org/gmane.lisp.clisp.general/6626"><code>Gmane/general/6626</code></a>/<a class="ulink" href="https://sourceforge.net/p/clisp/mailman/message/10142276/" target="_top">https://sourceforge.net/p/clisp/mailman/message/10142276/</a>
     <a class="gmane" href="http://article.gmane.org/gmane.lisp.clisp.general/6628"><code>Gmane/general/6628</code></a>/<a class="ulink" href="https://sourceforge.net/p/clisp/mailman/message/10142279/" target="_top">https://sourceforge.net/p/clisp/mailman/message/10142279/</a>
</dd></dl></div><p>Even more examples can be found in the file
 <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/tests/ffi.tst"><code class="filename">tests/ffi.tst</code></a>
 in the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> source distribution.</p></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="socket"></a>32.4. Socket Streams</h2></div><div><h3 class="subtitle"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platforms only.</span></span></h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#socket-intro">32.4.1. Introduction</a></span></dt><dt><span class="section"><a href="#socket-api">32.4.2. Socket API Reference</a></span></dt><dt><span class="section"><a href="#timeout-k">32.4.3. Argument <code class="constant">:TIMEOUT</code></a></span></dt></dl></div><div class="list-of-examples"><p><strong>List of Examples</strong></p><dl><dt>32.13. <a href="#socket-ex-server">Lisp read-eval-print loop server</a></dt><dt>32.14. <a href="#socket-ex-client">Lisp <span class="command"><strong>HTTP</strong></span> client</a></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="socket-intro"></a>32.4.1. Introduction</h3></div></div></div><div class="list-of-examples"><p><strong>List of Examples</strong></p><dl><dt>32.13. <a href="#socket-ex-server">Lisp read-eval-print loop server</a></dt><dt>32.14. <a href="#socket-ex-client">Lisp <span class="command"><strong>HTTP</strong></span> client</a></dt></dl></div><p><a class="ulink" href="http://www.freesoft.org/CIE/Topics/20.htm" target="_top">Sockets</a>
 are used for interprocess communications by processes running on the
 same host as well as by processes running on different hosts over a
 computer network.
 The most common kind of sockets is Internet stream sockets, and a
 high-level interface to them is described here.
 A more low level interface that closely follows the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> system
 calls is also available, see <a class="xref" href="#rawsock" title="33.17. Raw Socket Access">Section 33.17, “Raw Socket Access”</a>.</p><p>Two main varieties of sockets are interfaced to:
 </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="quote">“<span class="quote">active</span>”</span> sockets</span></dt><dd>correspond to <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-STREAM</code></a>s which are <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_b.html#bidirectional">bidirectional</a>
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s</dd><dt><span class="term"><span class="quote">“<span class="quote">passive</span>”</span> sockets</span></dt><dd>correspond to <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-SERVER</code></a>s which are a special
     kind of objects that are used to allow the other side to initiate
     interaction with lisp.</dd></dl></div><div class="example"><a id="socket-ex-server"></a><p class="title"><strong>Example 32.13. Lisp <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-1.html">read-eval-print loop</a> server</strong></p><div class="example-contents"><p>Here is a simple lisp <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-1.html">read-eval-print loop</a> server that waits for a remote
 connection and evaluates forms read from it:
</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET</code></a> ((server (<a class="link" href="#sose"><code class="function">SOCKET:SOCKET-SERVER</code></a>)))
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> t "~&amp;Waiting for a connection on ~S:~D~%"
          (<a class="link" href="#sose-hopo"><code class="function">SOCKET:SOCKET-SERVER-HOST</code></a> server) (<a class="link" href="#sose-hopo"><code class="function">SOCKET:SOCKET-SERVER-PORT</code></a> server))
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_unwind-protect.html" target="_top"><code class="function">UNWIND-PROTECT</code></a>
      ;; infinite loop, terminate with <span class="keycap"><strong>Control</strong></span>+<span class="keysym">C</span>
      (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_loop.html" target="_top"><code class="function">LOOP</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-open-stream.html" target="_top"><code class="function">WITH-OPEN-STREAM</code></a> (socket (<a class="link" href="#so-accept"><code class="function">SOCKET:SOCKET-ACCEPT</code></a> server))
              (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_multiple-value-bind.html" target="_top"><code class="function">MULTIPLE-VALUE-BIND</code></a> (local-host local-port) (<a class="link" href="#sost-local"><code class="function">SOCKET:SOCKET-STREAM-LOCAL</code></a> socket)
                (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_multiple-value-bind.html" target="_top"><code class="function">MULTIPLE-VALUE-BIND</code></a> (remote-host remote-port) (<a class="link" href="#sost-peer"><code class="function">SOCKET:SOCKET-STREAM-PEER</code></a> socket)
                  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> "~&amp;Connection: ~S:~D -- ~S:~D~%"
                          remote-host remote-port local-host local-port)))
              ;; loop is terminated when the remote host closes the connection or on <a class="link" href="#quit" title="31.3. Quitting CLISP"><code class="function">EXT:EXIT</code></a>
              (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_loop.html" target="_top"><code class="function">LOOP</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_whencm_unless.html" target="_top"><code class="function">WHEN</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a> :eof (<a class="link" href="#so-status"><code class="function">SOCKET:SOCKET-STATUS</code></a> (cons socket :input))) (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_return.html" target="_top"><code class="function">RETURN</code></a>))
                    (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_writecm_p_rintcm_princ.html" target="_top"><code class="function">PRINT</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eval.html" target="_top"><code class="function">EVAL</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_readcm_re_g-whitespace.html" target="_top"><code class="function">READ</code></a> socket)) socket)
                    ;; flush everything left in socket
                    (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_loop.html" target="_top"><code class="function">LOOP</code></a> :for c = (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-char-no-hang.html" target="_top"><code class="function">READ-CHAR-NO-HANG</code></a> socket nil nil) :while c)
                    (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_terpricm_fresh-line.html" target="_top"><code class="function">TERPRI</code></a> socket))))
    ;; make sure server is closed
    (<a class="link" href="#sose-close"><code class="function">SOCKET:SOCKET-SERVER-CLOSE</code></a> server)))
</pre><p>
</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">This opens a gaping security hole!</h3><p>Functions like <a href="impnotes.html#exec" class="olink"><code class="function">EXT:SHELL</code></a>, <a class="link" href="#exec" title="32.7.1. Shell"><code class="function">EXT:EXECUTE</code></a>, <a class="link" href="#run-prog"><code class="function">EXT:RUN-SHELL-COMMAND</code></a> will allow the
  remote host to execute arbitrary code with your permissions.
  While functions defined in lisp (like <a class="link" href="#run-prog"><code class="function">EXT:RUN-SHELL-COMMAND</code></a>) can be removed
  (using <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_fmakunbound.html" target="_top"><code class="function">FMAKUNBOUND</code></a>), the built-in functions (like <a href="impnotes.html#exec" class="olink"><code class="function">EXT:SHELL</code></a> and <a class="link" href="#exec" title="32.7.1. Shell"><code class="function">EXT:EXECUTE</code></a>)
  cannot be permanently removed from the <a href="clisp.html#runtime" class="olink">runtime</a>, and an experienced
  hacker will be able to invoke them even if you <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_fmakunbound.html" target="_top"><code class="function">FMAKUNBOUND</code></a> their names.
 </p><p>You should limit the socket server to local connections
  by passing the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> <span class="data"><code class="literal">"127.0.0.1"</code></span>
  as the <code class="constant">:INTERFACE</code> argument to <a class="link" href="#sose"><code class="function">SOCKET:SOCKET-SERVER</code></a>.</p></div><p>
</p></div></div><br class="example-break" /><div class="example"><a id="socket-ex-client"></a><p class="title"><strong>Example 32.14. Lisp <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> client</strong></p><div class="example-contents"><p>Here are a couple of simple lisp <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> clients that fetch a web
 page and a binary file, and upload a file:
</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defun.html" target="_top"><code class="function">DEFUN</code></a> wget-text (host page file <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> (port 80))
  ;; <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> requires the <code class="constant">:DOS</code> <a class="link" href="#newline" title="31.5.3. Line Terminators">line terminator</a>
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-open-stream.html" target="_top"><code class="function">WITH-OPEN-STREAM</code></a> (socket (<a class="link" href="#so-connect"><code class="function">SOCKET:SOCKET-CONNECT</code></a> port host <a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a> <code class="constant">:DOS</code>))
     (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> socket "GET ~A HTTP/1.0~2%" page)
     ;; dump the whole thing - header+data - into the output file
     (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-open-file.html" target="_top"><code class="function">WITH-OPEN-FILE</code></a> (out file :direction :output)
       (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_loop.html" target="_top"><code class="function">LOOP</code></a> :for line = (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-line.html" target="_top"><code class="function">READ-LINE</code></a> socket nil nil) :while line
          :do (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_write-str_m_write-line.html" target="_top"><code class="function">WRITE-LINE</code></a> line out)))))
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defun.html" target="_top"><code class="function">DEFUN</code></a> wget-binary (host page file <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> (port 80))
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-open-stream.html" target="_top"><code class="function">WITH-OPEN-STREAM</code></a> (socket (<a class="link" href="#so-connect"><code class="function">SOCKET:SOCKET-CONNECT</code></a> port host <a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a> <code class="constant">:DOS</code>))
    (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> socket "GET ~A HTTP/1.0~2%" page)
    (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_loop.html" target="_top"><code class="function">LOOP</code></a> :with content-length :for line = (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-line.html" target="_top"><code class="function">READ-LINE</code></a> socket nil nil)
      ;; header is separated from the data with a blank line
      :until (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_zerop.html" target="_top"><code class="function">ZEROP</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_length.html" target="_top"><code class="function">LENGTH</code></a> line)) :do
      (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_whencm_unless.html" target="_top"><code class="function">WHEN</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stringeqc_ng-not-lessp.html" target="_top"><code class="function">STRING=</code></a> line #1="Content-length: " :end1 #2=<a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_2-4-8-6.html"><span class="data"><code class="literal">#.</code></span></a>(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_length.html" target="_top"><code class="function">LENGTH</code></a> #1#))
        (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/spefor_setq.html" target="_top"><code class="function">SETQ</code></a> content-length (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_parse-integer.html" target="_top"><code class="function">PARSE-INTEGER</code></a> line :start #2#))
      ;; this will not work if the server does not supply the content-length header
      :finally (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_return.html" target="_top"><code class="function">RETURN</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET</code></a> ((data (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-array.html" target="_top"><code class="function">MAKE-ARRAY</code></a> content-length
                                               :element-type '<span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span>)))
                           ;; switch to binary i/o on socket
                           (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> socket) '<span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span>)
                           ;; read the whole file in one system call
                           (<a class="link" href="#rd-by-seq"><code class="function">EXT:READ-BYTE-SEQUENCE</code></a> data socket)
                           (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-open-file.html" target="_top"><code class="function">WITH-OPEN-FILE</code></a> (out file :direction :output
                                                <a class="link" href="#eltype"><code class="constant">:ELEMENT-TYPE</code></a> '<span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span>)
                             ;; write the whole file in one system call
                             (<a class="link" href="#wr-by-seq"><code class="function">EXT:WRITE-BYTE-SEQUENCE</code></a> data out))
                           data))))))
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defun.html" target="_top"><code class="function">DEFUN</code></a> wput (host page file <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> (port 80))
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-open-stream.html" target="_top"><code class="function">WITH-OPEN-STREAM</code></a> (socket (<a class="link" href="#so-connect"><code class="function">SOCKET:SOCKET-CONNECT</code></a> port host <a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a> <code class="constant">:DOS</code>))
    (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-open-file.html" target="_top"><code class="function">WITH-OPEN-FILE</code></a> (in file :direction :inptut <a class="link" href="#eltype"><code class="constant">:ELEMENT-TYPE</code></a> '<span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span>)
      (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET*</code></a> ((length (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_file-length.html" target="_top"><code class="function">FILE-LENGTH</code></a> in))
             (data (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-array.html" target="_top"><code class="function">MAKE-ARRAY</code></a> length :element-type '<span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span>)))
        ;; some servers may not understand the "Content-length" header
        (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> socket "PUT ~A HTTP/1.0~%Content-length: ~D~2%" page length)
        (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_stream-element-type.html" target="_top"><code class="function">STREAM-ELEMENT-TYPE</code></a> socket) '<span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span>)
        (<a class="link" href="#rd-by-seq"><code class="function">EXT:READ-BYTE-SEQUENCE</code></a> data in)
        (<a class="link" href="#wr-by-seq"><code class="function">EXT:WRITE-BYTE-SEQUENCE</code></a> data socket)))
    ;; not necessary if the server understands the "Content-length" header
    (<a class="link" href="#sost-shut"><code class="function">SOCKET:SOCKET-STREAM-SHUTDOWN</code></a> socket :output)
    ;; get the server response
    (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_loop.html" target="_top"><code class="function">LOOP</code></a> :for line = (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-line.html" target="_top"><code class="function">READ-LINE</code></a> socket nil nil) :while line :collect line)))
</pre></div></div><br class="example-break" /></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="socket-api"></a>32.4.2. Socket API Reference</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><a id="sose"></a><span class="term"><code class="code">(<a class="link" href="#sose"><code class="function">SOCKET:SOCKET-SERVER</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>port</code></em>
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:INTERFACE</code>
     <code class="constant">:BACKLOG</code>)</code></span></dt><dd><p class="simpara">This function creates a passive socket an binds a
    port to it.  The server exists to watch for client connection
    attempts.</p><p class="simpara">The optional argument is the port to use (non-negative
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_fixnum.html" target="_top"><code class="classname">FIXNUM</code></a>, <code class="literal">0</code> means assigned by the system).</p><p class="simpara">The <code class="constant">:BACKLOG</code> parameter defines maximum
    length of queue of pending connections (see
    <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/listen.html"><code class="function">listen</code></a>) and defaults to 1.</p><p class="simpara">The <code class="constant">:INTERFACE</code> parameter specifies the
    interface(s) on which the socket server will listen, and is either a
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>, interpreted as the interface <a class="rfc" href="http://www.ietf.org/rfc/rfc791.txt"><code><span class="command"><strong>IP</strong></span></code></a> address that will be
    bound, or a socket, from whose peer the connections will be made.</p><p class="simpara">Default is (for backward compatibility) to bind to all local
    interfaces, but for security reasons it is advisable to bind to
    the loopback interface <span class="data"><code class="literal">"127.0.0.1"</code></span> if
    you need only local connections.</p></dd><dt><a id="sose-close"></a><span class="term"><code class="code">(<a class="link" href="#sose-close"><code class="function">SOCKET:SOCKET-SERVER-CLOSE</code></a> <em class="replaceable"><code>socket-server</code></em>)</code></span></dt><dd>Closes down the server socket. <a class="link" href="#close" title="21.14. Function CLOSE">Just
     like streams</a>, <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-SERVER</code></a>s are closed at <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion.
    You should not rely on this however, because <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion times are not
    deterministic and the port assigned to the server socket cannot be
    reused until it is closed.</dd><dt><a id="sose-hopo"></a><span class="term"><code class="code">(<a class="link" href="#sose-hopo"><code class="function">SOCKET:SOCKET-SERVER-HOST</code></a> <em class="replaceable"><code>socket-server</code></em>)</code><br /></span><span class="term"><code class="code">(<a class="link" href="#sose-hopo"><code class="function">SOCKET:SOCKET-SERVER-PORT</code></a> <em class="replaceable"><code>socket-server</code></em>)</code></span></dt><dd>Returns the host mask indicating which hosts can
    connect to this server and the port which was bound using <a class="link" href="#sose"><code class="function">SOCKET:SOCKET-SERVER</code></a>.
 </dd><dt><a id="so-wait"></a><span class="term"><code class="code">(<a class="link" href="#so-wait"><code class="function">SOCKET:SOCKET-WAIT</code></a>
    <em class="replaceable"><code>socket-server</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <a class="link" href="#timeout-opt">[<em class="replaceable"><code>seconds</code></em> [<em class="replaceable"><code>microseconds</code></em>]]</a>)</code></span></dt><dd><a id="timeout-opt"></a>Wait for a fixed time for a
    connection on the <em class="replaceable"><code>socket-server</code></em> (a <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-SERVER</code></a>).
    Without a timeout argument, <a class="link" href="#so-wait"><code class="function">SOCKET:SOCKET-WAIT</code></a> blocks indefinitely.
    When timeout is zero, poll.
    Returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> when a connection is available (i.e., <a class="link" href="#so-accept"><code class="function">SOCKET:SOCKET-ACCEPT</code></a> will
    not block) and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> on timeout.</dd><dt><a id="so-accept"></a><span class="term"><code class="code">(<a class="link" href="#so-accept"><code class="function">SOCKET:SOCKET-ACCEPT</code></a> <em class="replaceable"><code>socket-server</code></em>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <a class="link" href="#eltype"><code class="constant">:ELEMENT-TYPE</code></a> <a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a> <a class="link" href="#buffered"><code class="constant">:BUFFERED</code></a> <a class="link" href="#timeout-k" title="32.4.3. Argument :TIMEOUT"><code class="constant">:TIMEOUT</code></a>)</code></span></dt><dd><p class="simpara">Waits for an attempt to connect to the <em class="replaceable"><code>socket-server</code></em> and
   creates the server-side <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_b.html#bidirectional">bidirectional</a> <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-STREAM</code></a> for the connection.
  </p><p class="simpara"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> if no connection is made in that time.
  </p></dd><dt><a id="so-connect"></a><span class="term"><code class="code">(<a class="link" href="#so-connect"><code class="function">SOCKET:SOCKET-CONNECT</code></a>
    <em class="replaceable"><code>port</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> [<em class="replaceable"><code>host</code></em>] <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    <a class="link" href="#eltype"><code class="constant">:ELEMENT-TYPE</code></a> <a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a> <a class="link" href="#buffered"><code class="constant">:BUFFERED</code></a> <a class="link" href="#timeout-k" title="32.4.3. Argument :TIMEOUT"><code class="constant">:TIMEOUT</code></a>)</code></span></dt><dd>Attempts to create a client-side <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_b.html#bidirectional">bidirectional</a>
   <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-STREAM</code></a>.  Blocks until the server accepts the connection, for
   no more than <a class="link" href="#timeout-k" title="32.4.3. Argument :TIMEOUT"><code class="constant">:TIMEOUT</code></a> <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-4-4.html">seconds</a>.  If it is 0, returns immediately
   and (probably) blocks on the next i/o operation (you can use
   <a class="link" href="#so-status"><code class="function">SOCKET:SOCKET-STATUS</code></a> to check whether it will actually block).
 </dd><dt><a id="so-status"></a><span class="term"><code class="code">(<a class="link" href="#so-status"><code class="function">SOCKET:SOCKET-STATUS</code></a>
                 <em class="replaceable"><code>socket-stream-or-list</code></em>
                 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <a class="link" href="#timeout-opt">[<em class="replaceable"><code>seconds</code></em> [<em class="replaceable"><code>microseconds</code></em>]]</a>)</code></span></dt><dd><p class="simpara">Checks whether it is possible to read from or write
    to a <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-STREAM</code></a> or whether a connection is available on a
    <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-SERVER</code></a> without blocking.</p><p class="simpara">This is similar to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_listen.html" target="_top"><code class="function">LISTEN</code></a>, which checks only one
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> and only for input, and <a class="link" href="#so-wait"><code class="function">SOCKET:SOCKET-WAIT</code></a>, which works only with
    <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-SERVER</code></a>s.</p><p class="simpara">We define <em class="replaceable"><code>status</code></em> for a <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-SERVER</code></a> or a <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-STREAM</code></a>
    to be <code class="constant">:ERROR</code> if <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/select.html"><code class="function">select</code></a> finds an exceptional condition pending
    on any of the argument <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a>s.</p><p class="simpara">Additionally, for a <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-SERVER</code></a>, we define
    <em class="replaceable"><code>status</code></em> to be <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> if a connection is available, i.e.,
    is <a class="link" href="#so-accept"><code class="function">SOCKET:SOCKET-ACCEPT</code></a> will not block, and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> otherwise.</p><p>Additionally, for a <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-STREAM</code></a>, we define <em class="replaceable"><code>status</code></em> in the
    given <em class="replaceable"><code>direction</code></em> (one of <code class="constant">:INPUT</code>, <code class="constant">:OUTPUT</code>, and <code class="constant">:IO</code>) to be
    </p><div class="variablelist"><a id="so-status-values"></a><p class="title"><strong>Possible status values for various directions:</strong></p><table border="0" class="variablelist"><colgroup><col align="left" valign="top" /><col /></colgroup><tbody><tr><td><p><span class="term"><code class="constant">:INPUT</code> status:</span></p></td><td><div class="variablelist"><table border="0" class="variablelist"><colgroup><col align="left" valign="top" /><col /></colgroup><tbody><tr><td><p><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></span></p></td><td>reading will block
        </td></tr><tr><td><p><span class="term"><code class="constant">:INPUT</code></span></p></td><td>some input is available
        </td></tr><tr><td><p><span class="term"><code class="constant">:EOF</code></span></p></td><td>the stream has reached its end
       </td></tr></tbody></table></div></td></tr><tr><td><p><span class="term"><code class="constant">:OUTPUT</code> status:</span></p></td><td><div class="variablelist"><table border="0" class="variablelist"><colgroup><col align="left" valign="top" /><col /></colgroup><tbody><tr><td><p><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></span></p></td><td>writing will block
        </td></tr><tr><td><p><span class="term"><code class="constant">:OUTPUT</code></span></p></td><td>output to the stream will not block
       </td></tr></tbody></table></div></td></tr><tr><td><p><span class="term"><code class="constant">:IO</code> status:</span></p></td><td><div class="informaltable"><a id="so-status-i-o"></a><table class="informaltable" border="1"><colgroup><col align="center" class="out" /><col align="center" class="nil" /><col align="center" class="inp" /><col align="center" class="eof" /></colgroup><thead><tr><th rowspan="2" align="center" valign="bottom">output status</th><th colspan="3" align="center">input status</th></tr><tr><th align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></th><th align="center"><code class="constant">:INPUT</code></th><th align="center"><code class="constant">:EOF</code></th></tr></thead><tbody><tr><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></td><td align="center"><code class="constant">:INPUT</code></td><td align="center"><code class="constant">:EOF</code></td></tr><tr><td align="center"><code class="constant">:OUTPUT</code></td><td align="center"><code class="constant">:OUTPUT</code></td><td align="center"><code class="constant">:IO</code></td><td align="center"><code class="constant">:APPEND</code></td></tr></tbody></table></div></td></tr></tbody></table></div><div class="variablelist"><p class="title"><strong>Possible values of
     <em class="replaceable"><code>socket-stream-or-list</code></em>:</strong></p><dl class="variablelist"><dt><span class="term"><a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-STREAM</code></a> or <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-SERVER</code></a></span></dt><dd>Returns the appropriate status, as defined
       above (<code class="constant">:IO</code> status for <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-STREAM</code></a>)
    </dd><dt><span class="term"><code class="code">(<a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-STREAM</code></a> . <em class="replaceable"><code>direction</code></em>)</code></span></dt><dd>Return the status in the specified direction
    </dd><dt><span class="term">a non-empty list of the above</span></dt><dd>Return a list of values, one for each element of the
       argument list (a la <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_mapccm_ma_istcm_mapcon.html" target="_top"><code class="function">MAPCAR</code></a>)</dd></dl></div><p class="simpara">If you want to avoid <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#cons">cons</a>ing[3] up a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_f.html#fresh">fresh</a> list, you can
    make the elements of <em class="replaceable"><code>socket-stream-or-list</code></em>
    to be <span class="data"><code class="literal">(<em class="replaceable"><code>socket-stream</code></em> <em class="replaceable"><code>direction</code></em> .
     <em class="replaceable"><code>x</code></em>)</code></span> or <span class="data"><code class="literal">(<em class="replaceable"><code>socket-server</code></em> . <em class="replaceable"><code>x</code></em>)</code></span>.
    Then <a class="link" href="#so-status"><code class="function">SOCKET:SOCKET-STATUS</code></a> will destructively modify its argument and replace
    <em class="replaceable"><code>x</code></em> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> with the status and return the modified list.
    You can pass this modified list to <a class="link" href="#so-status"><code class="function">SOCKET:SOCKET-STATUS</code></a> again.</p><p class="simpara">The optional arguments specify the timeout. <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> means
    wait forever, <code class="literal">0</code> means poll.</p><p class="simpara">The second value returned is the number of objects with
    non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> status, i.e., <span class="quote">“<span class="quote">actionable</span>”</span> objects.
    <a class="link" href="#so-status"><code class="function">SOCKET:SOCKET-STATUS</code></a> returns either due to a timeout or when this number is
    positive, i.e., if the timeout was <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and <a class="link" href="#so-status"><code class="function">SOCKET:SOCKET-STATUS</code></a> did
    return, then the second value is positive (this is the reason <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
    is <span class="strong"><strong>not</strong></span> treated as an empty <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>, but as an invalid
    argument).</p><p class="simpara">This is the interface to <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/select.html"><code class="function">select</code></a>
    (on some platforms, <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/poll.html"><code class="function">poll</code></a>),
    so it will work on any <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> which is based on a
    <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a>, e.g., <a href="impnotes.html#with-kbd" class="olink"><code class="varname">EXT:*KEYBOARD-INPUT*</code></a> and <a class="link" href="#open" title="21.12. Function OPEN">file</a>/<a class="link" href="#pipe" title="32.7.2. Pipes">pipe</a>/<a class="link" href="#socket" title="32.4. Socket Streams">socket</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s, as well as
    on <a class="link" href="#rawsock" title="33.17. Raw Socket Access">raw sockets</a>.</p></dd><dt><a id="sost-hopo"></a><span class="term"><code class="code">(<a class="link" href="#sost-hopo"><code class="function">SOCKET:SOCKET-STREAM-HOST</code></a> <em class="replaceable"><code>socket-stream</code></em>)</code><br /></span><span class="term"><code class="code">(<a class="link" href="#sost-hopo"><code class="function">SOCKET:SOCKET-STREAM-PORT</code></a> <em class="replaceable"><code>socket-stream</code></em>)</code></span></dt><dd>These two functions return information about the
    <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-STREAM</code></a>.</dd><dt><a id="sost-peer"></a><span class="term"><code class="code">(<a class="link" href="#sost-peer"><code class="function">SOCKET:SOCKET-STREAM-PEER</code></a>
    <em class="replaceable"><code>socket-stream</code></em> [<em class="replaceable"><code>do-not-resolve-p</code></em>])</code></span></dt><dd><p class="simpara">Given a <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-STREAM</code></a>, this function returns the
    name of the host on the opposite side of the connection and its port
    number; the server-side can use this to see who connected.</p><p class="simpara">When the optional second argument is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the hostname
    resolution is disabled and just the <a class="rfc" href="http://www.ietf.org/rfc/rfc791.txt"><code><span class="command"><strong>IP</strong></span></code></a> address is returned, without
    the <acronym class="acronym" title="Fully Qualified Domain Name">FQDN</acronym>.
 </p><p class="simpara">The <em class="replaceable"><code>socket-stream</code></em> argument can also be a
                       <a class="link" href="#rawsock" title="33.17. Raw Socket Access">raw socket</a>.</p></dd><dt><a id="sost-local"></a><span class="term"><code class="code">(<a class="link" href="#sost-local"><code class="function">SOCKET:SOCKET-STREAM-LOCAL</code></a>
    <em class="replaceable"><code>socket-stream</code></em> [<em class="replaceable"><code>do-not-resolve-p</code></em>])</code></span></dt><dd><p class="simpara">The dual to <a class="link" href="#sost-peer"><code class="function">SOCKET:SOCKET-STREAM-PEER</code></a> - same information,
   host name and port number, but for the local host.
   The difference from <a class="link" href="#sost-hopo"><code class="function">SOCKET:SOCKET-STREAM-HOST</code></a> and <a class="link" href="#sost-hopo"><code class="function">SOCKET:SOCKET-STREAM-PORT</code></a> is that this function
   asks the OS (and thus returns the correct trusted values) while the
   other two are just accessors to the internal data structure, and
   basically return the arguments given to the function which created
   the <em class="replaceable"><code>socket-stream</code></em>.</p><p class="simpara">The <em class="replaceable"><code>socket-stream</code></em> argument can also be a
                       <a class="link" href="#rawsock" title="33.17. Raw Socket Access">raw socket</a>.</p></dd><dt><a id="sost-shut"></a><span class="term"><code class="code">(<a class="link" href="#sost-shut"><code class="function">SOCKET:SOCKET-STREAM-SHUTDOWN</code></a> <em class="replaceable"><code>socket-stream</code></em>
    <em class="replaceable"><code>direction</code></em>)</code></span></dt><dd><p class="simpara">Some protocols provide for closing the connection
   in one <em class="replaceable"><code>direction</code></em> using <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/shutdown.html"><code class="function">shutdown</code></a>.
   This function provides an interface to this <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> system call.
   <em class="replaceable"><code>direction</code></em> should be <code class="constant">:INPUT</code> or <code class="constant">:OUTPUT</code>.  Note that you
   should still call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a> after you are done with your <em class="replaceable"><code>socket-stream</code></em>; this
   is best accomplished by using <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-open-stream.html" target="_top"><code class="function">WITH-OPEN-STREAM</code></a>.</p><p>All <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-STREAM</code></a>s are <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_b.html#bidirectional">bidirectional</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s (i.e., both <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_input-str_put-stream-p.html" target="_top"><code class="function">INPUT-STREAM-P</code></a>
   and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_input-str_put-stream-p.html" target="_top"><code class="function">OUTPUT-STREAM-P</code></a> return <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> for them).
   <a class="link" href="#sost-shut"><code class="function">SOCKET:SOCKET-STREAM-SHUTDOWN</code></a> <span class="emphasis"><em>breaks</em></span> this and turns its argument
   stream into an <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_i.html#input">input</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> (if <em class="replaceable"><code>direction</code></em> is <code class="constant">:OUTPUT</code>) or <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_o.html#output">output</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> (if
   <em class="replaceable"><code>direction</code></em> is <code class="constant">:INPUT</code>).
    Thus, the following important invariant is preserved: whenever
   </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> is open
    (i.e., <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_open-stream-p.html" target="_top"><code class="function">OPEN-STREAM-P</code></a> returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>) and</li><li class="listitem">a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> is an <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_i.html#input">input</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> (i.e., <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_input-str_put-stream-p.html" target="_top"><code class="function">INPUT-STREAM-P</code></a>
     returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>)</li></ul></div><p>
   the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> can be read from (e.g., with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-char.html" target="_top"><code class="function">READ-CHAR</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-byte.html" target="_top"><code class="function">READ-BYTE</code></a>).
   </p><p class="simpara">The <em class="replaceable"><code>socket-stream</code></em> argument can also be a
                       <a class="link" href="#rawsock" title="33.17. Raw Socket Access">raw socket</a>.</p></dd><dt><a id="so-opt"></a><span class="term"><code class="code">(<a class="link" href="#so-opt"><code class="function">SOCKET:SOCKET-OPTIONS</code></a> <em class="replaceable"><code>socket-server</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a>
    {<em class="replaceable"><code>option</code></em>}*)</code></span></dt><dd><p class="simpara">Query and, optionally, set socket options using
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html"><code class="function">getsockopt</code></a> and <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html"><code class="function">setsockopt</code></a>.
   An <em class="replaceable"><code>option</code></em> is a keyword, optionally followed by the new value.
   When the new value is not supplied, <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html"><code class="function">setsockopt</code></a> is not called.
   For each option the old (or current, if new value was not supplied)
   value is returned.  E.g., <code class="code">(<a class="link" href="#so-opt"><code class="function">SOCKET:SOCKET-OPTIONS</code></a> <em class="replaceable"><code>socket-server</code></em>
   :SO-LINGER 1 :SO-RCVLOWAT)</code> returns 2 values: <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the old
   value of the <code class="constant">:SO-LINGER</code> option, and 1, the
   current value of the <code class="constant">:SO-RCVLOWAT</code> option.
  </p><p class="simpara">The <em class="replaceable"><code>socket-stream</code></em> argument can also be a
                       <a class="link" href="#rawsock" title="33.17. Raw Socket Access">raw socket</a>.</p></dd><dt><a id="st-handles"></a><span class="term"><code class="code">(<a class="link" href="#st-handles"><code class="function">EXT:STREAM-HANDLES</code></a>
    <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd>Return the input and output OS <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a>s of the
    <em class="replaceable"><code>stream</code></em> as <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_m.html#multiple_values">multiple values</a>.  See <a class="xref" href="#rawsock" title="33.17. Raw Socket Access">Section 33.17, “Raw Socket Access”</a>.
 </dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="timeout-k"></a>32.4.3. Argument <a class="link" href="#timeout-k" title="32.4.3. Argument :TIMEOUT"><code class="constant">:TIMEOUT</code></a></h3></div></div></div><p>The <a class="link" href="#timeout-k" title="32.4.3. Argument :TIMEOUT"><code class="constant">:TIMEOUT</code></a> argument specifies the number of <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-4-4.html">seconds</a> to wait for
 an event. The value may be a</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">a non-negative <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_real.html" target="_top"><code class="classname">REAL</code></a> or</li><li class="listitem">a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> <span class="data"><code class="literal">(sec usec)</code></span>
  or</li><li class="listitem">a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_cons.html" target="_top"><code class="classname">CONS</code></a> cell <span class="data"><code class="literal">(sec .
   usec)</code></span>.</li></ul></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="mt"></a>32.5. Multiple Threads of Execution</h2></div><div><h3 class="subtitle"><span class="plat-dep">Platform Dependent: <span class="plat-dep">Only in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> built <span class="strong"><strong>with</strong></span>
  configure-time flag <code class="option">--with-threads</code>.</span></span></h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mt-intro">32.5.1. Introduction</a></span></dt><dt><span class="section"><a href="#mt-general">32.5.2. General principles</a></span></dt><dd><dl><dt><span class="section"><a href="#mt-parallelizability">32.5.2.1. Parallelizability</a></span></dt><dt><span class="section"><a href="#mt-symvalue">32.5.2.2. Special Variable Values</a></span></dt><dt><span class="section"><a href="#mt-package">32.5.2.3. Packages</a></span></dt><dt><span class="section"><a href="#mt-clos">32.5.2.4. <span class="command"><strong>CLOS</strong></span></a></span></dt><dt><span class="section"><a href="#mt-mutable">32.5.2.5. Hash Tables, Sequences, and other   mutable objects</a></span></dt><dd><dl><dt><span class="section"><a href="#mt-random">32.5.2.5.1. <code class="function">RANDOM</code> and <code class="classname">RANDOM-STATE</code></a></span></dt></dl></dd><dt><span class="section"><a href="#mt-unsafe">32.5.2.6. Examples of thread-unsafe code</a></span></dt></dl></dd><dt><span class="section"><a href="#mt-api">32.5.3. Thread API reference</a></span></dt></dl></div><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>This functionality is <span class="strong"><strong><a class="ulink" href="http://www.cygwin.com/acronyms/#PTC" target="_top">experimental</a></strong></span>.</p><p>Use it at your own risk.</p><p>Discuss it on <a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-devel/">clisp-devel</a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mt-intro"></a>32.5.1. Introduction</h3></div></div></div><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> uses the OS threads to implement multiple threads of execution.
 Two flavors are supported: <a class="ulink" href="http://www.opengroup.org/austin/papers/posix_faq.html" target="_top"><span class="platform">POSIX</span></a> and <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>. Both are preemptive.</p><p>All symbols are exported from the package <a class="link" href="#mt" title="32.5. Multiple Threads of Execution"><strong class="package"><span class="quote">“<span class="quote">THREADS</span>”</span></strong></a>, which has nicknames
 <strong class="package"><span class="quote">“<span class="quote">MT</span>”</span></strong> (for <span class="emphasis"><em>MultiThreading</em></span>) and
 <strong class="package"><span class="quote">“<span class="quote">MP</span>”</span></strong> (for <span class="emphasis"><em>MultiProcessing</em></span>).
 When this functionality is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a>
 contains the symbol <code class="constant">:MT</code>.</p><p>See also <a class="xref" href="#gc-mt" title="35.8. Garbage Collection and Multithreading">Section 35.8, “Garbage Collection and Multithreading”</a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mt-general"></a>32.5.2. General principles</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mt-parallelizability">32.5.2.1. Parallelizability</a></span></dt><dt><span class="section"><a href="#mt-symvalue">32.5.2.2. Special Variable Values</a></span></dt><dt><span class="section"><a href="#mt-package">32.5.2.3. Packages</a></span></dt><dt><span class="section"><a href="#mt-clos">32.5.2.4. <span class="command"><strong>CLOS</strong></span></a></span></dt><dt><span class="section"><a href="#mt-mutable">32.5.2.5. Hash Tables, Sequences, and other   mutable objects</a></span></dt><dd><dl><dt><span class="section"><a href="#mt-random">32.5.2.5.1. <code class="function">RANDOM</code> and <code class="classname">RANDOM-STATE</code></a></span></dt></dl></dd><dt><span class="section"><a href="#mt-unsafe">32.5.2.6. Examples of thread-unsafe code</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mt-parallelizability"></a>32.5.2.1. Parallelizability</h4></div></div></div><p>A program developed for a single-threaded world which shares no
 application objects with programs running in other threads must run
 fine, without problems.</p><p>Specfically:
 if, in a single-threaded world, execution of program A before program B
 produces semantically the same results as execution of program B before
 program A, then in a multithreaded world, it is possible to run A and B
 simultaneously in different threads, and the result will be the same as
 in the two single-threaded cases (A before B, or B before A).
 </p><div class="itemizedlist"><p class="title"><strong>Summary</strong></p><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">If A and B have no common objects, then the
    implementation ensures that the principle is fulfilled.</li><li class="listitem">If A and B share some objects, the implementation
    allows the programs to satisfy the principle with little effort.
</li></ul></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mt-symvalue"></a>32.5.2.2. Special Variable Values</h4></div></div></div><p>Every <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-1-2.html">dynamic variable</a> has a global value that can be shared across all
 <a class="link" href="#thread"><span class="type">MT:THREAD</span></a>s.</p><p>Bindings of <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-2-1-1-2.html">dynamic variable</a>s (via <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET</code></a>/<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET*</code></a>/<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_multiple-value-bind.html" target="_top"><code class="function">MULTIPLE-VALUE-BIND</code></a>)
 are local to <a class="link" href="#thread"><span class="type">MT:THREAD</span></a>s, i.e. every <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a> has a different value cell in
 each <a class="link" href="#thread"><span class="type">MT:THREAD</span></a>.  <a class="link" href="#symbol-value-thread"><code class="function">MT:SYMBOL-VALUE-THREAD</code></a> can be used to inspect and modify
 these thread local bindings.</p><p>Threads do not inherit dynamic bindings from the parent thread.</p><p>Example:</p><pre class="programlisting">
(defvar *global* 1)<strong>	; </strong><em class="lineannotation"><span class="lineannotation">create a <a class="link" href="#mt-symvalue" title="32.5.2.2. Special Variable Values"><span class="emphasis"><em>Global Variable</em></span></a></span></em>
(defun thread-1 ()
   <strong>	; </strong><em class="lineannotation"><span class="lineannotation">here *global* and (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_symbol-value.html" target="_top"><code class="function">SYMBOL-VALUE</code></a> *global*) will be 1 not 2!</span></em>
  (setq *global* 5)<strong>	; </strong><em class="lineannotation"><span class="lineannotation">change the <a class="link" href="#mt-symvalue" title="32.5.2.2. Special Variable Values"><span class="emphasis"><em>Global Variable</em></span></a> value</span></em>
  (let ((*global* 10))<strong>	; </strong><em class="lineannotation"><span class="lineannotation"><a class="link" href="#mt-symvalue" title="32.5.2.2. Special Variable Values"><span class="emphasis"><em>Per-Thread Variable</em></span></a> value is initialized</span></em>
    (setq *global* 20)<strong>	; </strong><em class="lineannotation"><span class="lineannotation"><a class="link" href="#mt-symvalue" title="32.5.2.2. Special Variable Values"><span class="emphasis"><em>Per-Thread Variable</em></span></a> value is changed</span></em>
    <strong>	; </strong><em class="lineannotation"><span class="lineannotation"><a class="link" href="#mt-symvalue" title="32.5.2.2. Special Variable Values"><span class="emphasis"><em>Global Variable</em></span></a> value is not accessible here (only via <a class="link" href="#symbol-value-thread"><code class="function">MT:SYMBOL-VALUE-THREAD</code></a>)</span></em>
    )
  (setq *global* 30))<strong>	; </strong><em class="lineannotation"><span class="lineannotation"><a class="link" href="#mt-symvalue" title="32.5.2.2. Special Variable Values"><span class="emphasis"><em>Global Variable</em></span></a> value is modified again</span></em>
(let ((*global* 2))<strong>	; </strong><em class="lineannotation"><span class="lineannotation"><a class="link" href="#mt-symvalue" title="32.5.2.2. Special Variable Values"><span class="emphasis"><em>Per-Thread Variable</em></span></a> value is initialized</span></em>
  (<a class="link" href="#make-thread"><code class="function">MT:MAKE-THREAD</code></a> #'thread-1))
</pre></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mt-package"></a>32.5.2.3. Packages</h4></div></div></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>Locking discussed in this section has nothing to do with
  <a class="link" href="#pack-lock" title="11.2. Constraints on the “COMMON-LISP” Package for Conforming Programs - package locking sec_11-1-2-1-2"><code class="function">EXT:PACKAGE-LOCK</code></a>.</p></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_package.html" target="_top"><code class="classname">PACKAGE</code></a> objects have an internal <a class="link" href="#mutex"><span class="type">MT:MUTEX</span></a> and are locked by
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_intern.html" target="_top"><code class="function">INTERN</code></a> before adding a symbol (if <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_find-symbol.html" target="_top"><code class="function">FIND-SYMBOL</code></a> fails).  All
 modifications of internal package data are guarded by this <a class="link" href="#mutex"><span class="type">MT:MUTEX</span></a>.</p><p>While iterating over package symbols with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_do-symbol_-all-symbols.html" target="_top"><code class="function">DO-SYMBOLS</code></a>,
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_do-symbol_-all-symbols.html" target="_top"><code class="function">DO-EXTERNAL-SYMBOLS</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_do-symbol_-all-symbols.html" target="_top"><code class="function">DO-ALL-SYMBOLS</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-package-iterator.html" target="_top"><code class="function">WITH-PACKAGE-ITERATOR</code></a>
 or the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_loop.html" target="_top"><code class="function">LOOP</code></a> <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_6-1-2-1-7.html">for-as-package
  subclause</a> the package being iterated over is also locked.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mt-clos"></a>32.5.2.4. <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a></h4></div><div><h5 class="subtitle">This information is likely to change in the near future</h5></div></div></div><p><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> is <span class="strong"><strong>not</strong></span> thread-safe. <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a>,
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defstruct.html" target="_top"><code class="function">DEFSTRUCT</code></a> modify <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> without any locking and may
 interfere with each other.</p><p>It is recommended that all code is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_load.html" target="_top"><code class="function">LOAD</code></a>ed <span class="strong"><strong>before</strong></span>
 any <a class="link" href="#thread"><span class="type">MT:THREAD</span></a>s are spawned.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mt-mutable"></a>32.5.2.5. Hash Tables, Sequences, and other
  mutable objects</h4></div><div><h5 class="subtitle">If you want to shoot yourself, it is <span class="emphasis"><em>your</em></span>
 responsibility to wear armor.</h5></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#mt-random">32.5.2.5.1. <code class="function">RANDOM</code> and <code class="classname">RANDOM-STATE</code></a></span></dt></dl></div><p>Nothing is ever locked automatically (automatic locking will
 impose an unjustifiable penalty on <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a>s and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_sequence.html" target="_top"><code class="classname">SEQUENCE</code></a>s
 local to threads), so the user must use locks when sharing
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a>s, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_sequence.html" target="_top"><code class="classname">SEQUENCE</code></a>s and user-defined mutable objects between
 threads.</p><p>This approach is consistent with the usual <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> approach:
 </p><div class="blockquote"><table border="0" class="blockquote" style="width: 100%; cellspacing: 0; cellpadding: 0;" summary="Block quote"><tr><td width="10%" valign="top"> </td><td width="80%" valign="top"><p>The consequences are undefined when code executed during an
   object-traversing operation destructively modifies the object in a
   way that might affect the ongoing traversal operation...
 </p></td><td width="10%" valign="top"> </td></tr><tr><td width="10%" valign="top"> </td><td colspan="2" align="right" valign="top">--<span class="attribution"><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-6.html">[sec_3-6]</a></span></td></tr></table></div><p>
 </p><div class="blockquote"><table border="0" class="blockquote" style="width: 100%; cellspacing: 0; cellpadding: 0;" summary="Block quote"><tr><td width="10%" valign="top"> </td><td width="80%" valign="top"><p>If an object O1 is used as a key in a hash table H and is then
   visibly modified with regard to the equivalence test of H, then the
   consequences are unspecified if O1 is used as a key in further
   operations on H...</p></td><td width="10%" valign="top"> </td></tr><tr><td width="10%" valign="top"> </td><td colspan="2" align="right" valign="top">--<span class="attribution"><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_18-1-2.html">[sec_18-1-2]</a></span></td></tr></table></div><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="mt-random"></a>32.5.2.5.1. <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_random.html" target="_top"><code class="function">RANDOM</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_random-state.html" target="_top"><code class="classname">RANDOM-STATE</code></a></h5></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_random.html" target="_top"><code class="function">RANDOM</code></a> modifies a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_random-state.html" target="_top"><code class="classname">RANDOM-STATE</code></a> <span class="strong"><strong>without</strong></span> locking, which
means that you <span class="strong"><strong>cannot</strong></span> carelessly share such objects between threads.
However, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_strandom-statest.html" target="_top"><code class="varname">*RANDOM-STATE*</code></a> is bound per-thread (see <a class="link" href="#make-thread"><code class="function">MT:MAKE-THREAD</code></a> and
<a class="link" href="#default-special-bindings"><code class="varname">MT:*DEFAULT-SPECIAL-BINDINGS*</code></a>), i.e., each thread has its own value and
thus <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_random.html" target="_top"><code class="function">RANDOM</code></a> <span class="strong"><strong>is</strong></span> thread-safe.</p></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="mt-unsafe"></a>32.5.2.6. Examples of thread-unsafe code</h4></div></div></div><p>Here are some forms whose results are undefined if two threads
 evaluate them without locking:</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_incfcm_decf.html" target="_top"><code class="function">INCF</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_gethash.html" target="_top"><code class="function">GETHASH</code></a> x global-ht 0))<strong>	; </strong><em class="lineannotation"><span class="lineannotation">see <a class="xref" href="#mt-mutable" title="32.5.2.5. Hash Tables, Sequences, and other mutable objects">Section 32.5.2.5, “Hash Tables, Sequences, and other   mutable objects”</a></span></em>
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_aref.html" target="_top"><code class="function">AREF</code></a> global-array ...) ...)<strong>	; </strong><em class="lineannotation"><span class="lineannotation">ditto</span></em>
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a> <em class="replaceable"><code>generic-function</code></em> (...) ...)<strong>	; </strong><em class="lineannotation"><span class="lineannotation">see <a class="xref" href="#mt-clos" title="32.5.2.4. CLOS">Section 32.5.2.4, “<span class="command"><strong>CLOS</strong></span>”</a></span></em>
</pre><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>The above code may result in a segfault!</p><p>This is the reason why the multithreading support is still
<span class="strong"><strong><a class="ulink" href="http://www.cygwin.com/acronyms/#PTC" target="_top">experimental</a></strong></span>. However, if you do not share global <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a>s
between your threads and define all your <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> methods <span class="strong"><strong>before</strong></span>
spawning threads, multithreading should work fine.</p></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mt-api"></a>32.5.3. Thread API reference</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><a id="thread"></a><span class="term"><a class="link" href="#thread"><span class="type">MT:THREAD</span></a></span></dt><dd><p class="simpara">The type of the object returned by <a class="link" href="#make-thread"><code class="function">MT:MAKE-THREAD</code></a>.</p><p class="simpara">Each <a class="link" href="#thread"><span class="type">MT:THREAD</span></a> represent a separate computation, executed in
   parallel to each other.</p></dd><dt><a id="make-thread"></a><span class="term"><code class="code">(<a class="link" href="#make-thread"><code class="function">MT:MAKE-THREAD</code></a> <em class="replaceable"><code>function</code></em>
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:NAME</code> :INITIAL-BINDINGS :CSTACK-SIZE :VSTACK-SIZE)</code></span></dt><dd><p class="simpara">Start a new named <a class="link" href="#thread"><span class="type">MT:THREAD</span></a> running <em class="replaceable"><code>function</code></em>.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:INITIAL-BINDINGS</code></span></dt><dd><p class="simpara">an <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_a.html#association_list">association list</a> of <span class="data"><code class="literal">(<em class="replaceable"><code>symbol</code></em>
       . <em class="replaceable"><code>form</code></em>)</code></span>.
      The <em class="replaceable"><code>form</code></em>s are <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eval.html" target="_top"><code class="function">EVAL</code></a>uated in the context of the new thread
      and <em class="replaceable"><code>symbol</code></em>s are bound to the result in the thread before <em class="replaceable"><code>function</code></em> is
      called. The default value is <a class="link" href="#default-special-bindings"><code class="varname">MT:*DEFAULT-SPECIAL-BINDINGS*</code></a>.</p><p class="simpara">The main purpose of this argument is to initialize some
      global data that should not be shared between threads, e.g.,
      <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_strandom-statest.html" target="_top"><code class="varname">*RANDOM-STATE*</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_streadtablest.html" target="_top"><code class="varname">*READTABLE*</code></a>.</p><p class="simpara">When using <code class="constant">:INITIAL-BINDINGS</code> it is
      best to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_cons.html" target="_top"><code class="function">CONS</code></a> the application-specific data in front of
      <a class="link" href="#default-special-bindings"><code class="varname">MT:*DEFAULT-SPECIAL-BINDINGS*</code></a> or copy and modify it to fit the
      application needs.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>When the same <em class="replaceable"><code>symbol</code></em> appears in this <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_a.html#association_list">association list</a> multiple
     times, the <span class="emphasis"><em>first</em></span> occurrence determines the value.
   </p></div></dd><dt><span class="term"><code class="constant">:CSTACK-SIZE</code></span></dt><dd>the size in bytes of the control (<a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>) stack.
      If 0, the value is decided by the OS.</dd><dt><span class="term"><code class="constant">:VSTACK-SIZE</code></span></dt><dd>the size of the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> in <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="type">object</span></a>s.
     The default value is calculated based on the <code class="option"><a href="clisp.html#opt-memsize" class="olink">-m</a></code> option
     used when <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> was started.
     If 0, the value will be the same as that of the calling thread.
  </dd></dl></div><p class="simpara">If <a class="link" href="#thread"><span class="type">MT:THREAD</span></a> creation fails (e.g., due to a lack of system
   memory), a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_control-error.html" target="_top"><code class="classname">CONTROL-ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.</p><p class="simpara">Cf. <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_create.html"><code class="function">pthread_create</code></a>.</p></dd><dt><a id="threadp"></a><span class="term"><code class="code">(<a class="link" href="#threadp"><code class="function">MT:THREADP</code></a> <em class="replaceable"><code>object</code></em>)</code></span></dt><dd>Check whether the object is of type <a class="link" href="#thread"><span class="type">MT:THREAD</span></a>.
</dd><dt><a id="thread-yield"></a><span class="term"><code class="code">(<a class="link" href="#thread-yield"><code class="function">MT:THREAD-YIELD</code></a> <em class="replaceable"><code>thread</code></em>)</code></span></dt><dd><p class="simpara">Relinquish the CPU.  The <em class="replaceable"><code>thread</code></em> is placed at the end
   of the run queue and another thread is scheduled to run.</p><p class="simpara">Cf. <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/sched_yield.html"><code class="function">sched_yield</code></a>.</p></dd><dt><a id="thread-interrupt"></a><span class="term"><code class="code">(<a class="link" href="#thread-interrupt"><code class="function">MT:THREAD-INTERRUPT</code></a> <em class="replaceable"><code>thread</code></em>
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:FUNCTION</code> <code class="constant">:OVERRIDE</code> <code class="constant">:ARGUMENTS</code>)</code></span></dt><dd><p class="simpara">Interrupt the normal execution flow in <em class="replaceable"><code>thread</code></em> and ask
   it to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_apply.html" target="_top"><code class="function">APPLY</code></a> <em class="replaceable"><code>function</code></em> to <em class="replaceable"><code>arguments</code></em>.</p><p class="simpara">Use <code class="code">(<a class="link" href="#thread-interrupt"><code class="function">MT:THREAD-INTERRUPT</code></a> <em class="replaceable"><code>thread</code></em> <code class="constant">:FUNCTION</code> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>)</code>
   to debug <em class="replaceable"><code>thread</code></em> and <code class="code">(<a class="link" href="#thread-interrupt"><code class="function">MT:THREAD-INTERRUPT</code></a> <em class="replaceable"><code>thread</code></em> <code class="constant">:FUNCTION</code>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>)</code> to terminate <em class="replaceable"><code>thread</code></em>.</p><p class="simpara">The <code class="constant">:OVERRIDE</code> argument overrides <a class="link" href="#with-deferred-interrupts"><code class="function">MT:WITH-DEFERRED-INTERRUPTS</code></a>
   and should be used with extreme care.</p><p class="simpara">Threads can only be interrupted at a point where the <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion
   can run, see <a class="xref" href="#gc-mt" title="35.8. Garbage Collection and Multithreading">Section 35.8, “Garbage Collection and Multithreading”</a>.</p><p class="simpara">Currently on <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> blocking I/O cannot be interrupted.
   The interrupt will be handled after the call returns.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>Thread may be interrupted inside <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_unwind-protect.html" target="_top"><code class="function">UNWIND-PROTECT</code></a>'s
    cleanup forms and on non-local exit from <em class="replaceable"><code>function</code></em> -
    they may not execute entirely.  In order to prevent this,
    <a class="link" href="#with-deferred-interrupts"><code class="function">MT:WITH-DEFERRED-INTERRUPTS</code></a> is provided.</p></div></dd><dt><a id="thread-name"></a><span class="term"><code class="code">(<a class="link" href="#thread-name"><code class="function">MT:THREAD-NAME</code></a> <em class="replaceable"><code>thread</code></em>)</code></span></dt><dd>Return the <em class="replaceable"><code>name</code></em> of the <em class="replaceable"><code>thread</code></em>.
</dd><dt><a id="thread-active-p"></a><span class="term"><code class="code">(<a class="link" href="#thread-active-p"><code class="function">MT:THREAD-ACTIVE-P</code></a>
   <em class="replaceable"><code>thread</code></em>)</code></span></dt><dd><p class="simpara">Return <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if the thread has already terminated
   and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> otherwise.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>By the time this function returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>, <em class="replaceable"><code>thread</code></em> may have
    already terminated anyway.</p></div></dd><dt><a id="current-thread"></a><span class="term"><code class="code">(<a class="link" href="#current-thread"><code class="function">MT:CURRENT-THREAD</code></a>)</code></span></dt><dd>Return the <a class="link" href="#thread"><span class="type">MT:THREAD</span></a> object encapsulating the caller.
</dd><dt><a id="list-threads"></a><span class="term"><code class="code">(<a class="link" href="#list-threads"><code class="function">MT:LIST-THREADS</code></a>)</code></span></dt><dd><p class="simpara">Return the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of all currently running <a class="link" href="#thread"><span class="type">MT:THREAD</span></a>s.
  </p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>By the time this function returns, the set of
    actually running threads may have a single intersection with the
    return value - the <a class="link" href="#current-thread"><code class="function">MT:CURRENT-THREAD</code></a>.
</p></div></dd><dt><a id="mutex"></a><span class="term"><a class="link" href="#mutex"><span class="type">MT:MUTEX</span></a></span></dt><dd><p class="simpara">The type of the object return by <a class="link" href="#make-mutex"><code class="function">MT:MAKE-MUTEX</code></a>.</p><p class="simpara">This represents a <span class="emphasis"><em>lock</em></span>, i.e., a way to
   prevent different threads from doing something at the same time,
   e.g., modifying the same object.</p></dd><dt><a id="mutexp"></a><span class="term"><code class="code">(<a class="link" href="#mutexp"><code class="function">MT:MUTEXP</code></a> <em class="replaceable"><code>object</code></em>)</code></span></dt><dd>Check whether the object is of type <a class="link" href="#mutex"><span class="type">MT:MUTEX</span></a>.
</dd><dt><a id="make-mutex"></a><span class="term"><code class="code">(<a class="link" href="#make-mutex"><code class="function">MT:MAKE-MUTEX</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   <code class="constant">:NAME</code> <code class="constant">:RECURSIVE-P</code>)</code></span></dt><dd><p class="simpara">Create new <a class="link" href="#mutex"><span class="type">MT:MUTEX</span></a> object - not locked by any thread.
   <code class="constant">:NAME</code> should be a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> describing the mutex (this really helps
   debugging deadlocks).  When <em class="replaceable"><code>RECURSIVE-P</code></em> is
   non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, a recursive <a class="link" href="#mutex"><span class="type">MT:MUTEX</span></a> is created i.e., a thread can acquire
   the mutex repeatedly (and should, of course, release it for each
   successful acquisition).</p><p class="simpara">Cf. <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_mutex_init.html"><code class="function">pthread_mutex_init</code></a>.</p></dd><dt><a id="mutex-name"></a><span class="term"><code class="code">(<a class="link" href="#mutex-name"><code class="function">MT:MUTEX-NAME</code></a> <em class="replaceable"><code>thread</code></em>)</code></span></dt><dd>Return the <em class="replaceable"><code>name</code></em> of the <a class="link" href="#mutex"><span class="type">MT:MUTEX</span></a>.
</dd><dt><a id="mutex-lock"></a><span class="term"><code class="code">(<a class="link" href="#mutex-lock"><code class="function">MT:MUTEX-LOCK</code></a> <em class="replaceable"><code>mutex</code></em>
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <a class="link" href="#timeout-k" title="32.4.3. Argument :TIMEOUT"><code class="constant">:TIMEOUT</code></a>)</code></span></dt><dd><p class="simpara">Acquire the <em class="replaceable"><code>mutex</code></em>.  If <em class="replaceable"><code>mutex</code></em> is locked by
   another thread, the call blocks and waits up to <a class="link" href="#timeout-k" title="32.4.3. Argument :TIMEOUT"><code class="constant">:TIMEOUT</code></a> <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-4-4.html">seconds</a>.
   If <a class="link" href="#timeout-k" title="32.4.3. Argument :TIMEOUT"><code class="constant">:TIMEOUT</code></a> is not specified, waits forever.</p><p class="simpara">Return <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> on a successful locking of <em class="replaceable"><code>mutex</code></em>, and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> on
   timeout.</p><p>If the calling thread has already acquired <em class="replaceable"><code>mutex</code></em>, then
   </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">if <em class="replaceable"><code>mutex</code></em> is recursive, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> is
      returned (for each recursive <a class="link" href="#mutex-lock"><code class="function">MT:MUTEX-LOCK</code></a> there should be a
      separate <a class="link" href="#mutex-unlock"><code class="function">MT:MUTEX-UNLOCK</code></a>);</li><li class="listitem">If <em class="replaceable"><code>mutex</code></em> is non-recursive an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed to
      avoid a deadlock.</li></ul></div><p class="simpara">Cf. <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_mutex_lock.html"><code class="function">pthread_mutex_lock</code></a>.</p></dd><dt><a id="mutex-unlock"></a><span class="term"><code class="code">(<a class="link" href="#mutex-unlock"><code class="function">MT:MUTEX-UNLOCK</code></a>
   <em class="replaceable"><code>mutex</code></em>)</code></span></dt><dd><p class="simpara">Release (unlock) <em class="replaceable"><code>mutex</code></em>. If the calling thread is
   not locking <em class="replaceable"><code>mutex</code></em>, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.</p><p class="simpara">Cf. <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_mutex_unlock.html"><code class="function">pthread_mutex_unlock</code></a>.</p></dd><dt><a id="mutex-owner"></a><span class="term"><code class="code">(<a class="link" href="#mutex-owner"><code class="function">MT:MUTEX-OWNER</code></a>
   <em class="replaceable"><code>mutex</code></em>)</code></span></dt><dd><p class="simpara">Return the <a class="link" href="#thread"><span class="type">MT:THREAD</span></a> that owns (locks) <em class="replaceable"><code>mutex</code></em>,
   or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if <em class="replaceable"><code>mutex</code></em> is not locked.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>By the time this function returns the <em class="replaceable"><code>mutex</code></em>
    ownership may have changed (unless the owner is the
    <a class="link" href="#current-thread"><code class="function">MT:CURRENT-THREAD</code></a>). The function is mostly useful for debugging
    deadlocks.</p></div></dd><dt><a id="mutex-recursive-p"></a><span class="term"><code class="code">(<a class="link" href="#mutex-recursive-p"><code class="function">MT:MUTEX-RECURSIVE-P</code></a>
   <em class="replaceable"><code>mutex</code></em>)</code></span></dt><dd>Return a indicator whether <em class="replaceable"><code>mutex</code></em> is recursive.
</dd><dt><a id="with-mutex-lock"></a><span class="term"><code class="code">(<a class="link" href="#with-mutex-lock"><code class="function">MT:WITH-MUTEX-LOCK</code></a> (<em class="replaceable"><code>mutex</code></em>)
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> <em class="replaceable"><code>body</code></em>)</code></span></dt><dd>Execute <em class="replaceable"><code>body</code></em> with <em class="replaceable"><code>mutex</code></em> locked.
   Upon exit <em class="replaceable"><code>mutex</code></em> is released. Return whatever <em class="replaceable"><code>body</code></em> returns.
</dd><dt><a id="exemption"></a><span class="term"><a class="link" href="#exemption"><span class="type">MT:EXEMPTION</span></a></span></dt><dd><p class="simpara">The type of the object returned by <a class="link" href="#make-exemption"><code class="function">MT:MAKE-EXEMPTION</code></a>.
   These correspond to the <a class="ulink" href="http://www.opengroup.org/austin/papers/posix_faq.html" target="_top"><span class="platform">POSIX</span></a> condition variables,
   see <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/pthread.h.html">&lt;<code class="filename">pthread.h</code>&gt;</a>.</p><p class="simpara">These objects allow broadcasting state from one <a class="link" href="#thread"><span class="type">MT:THREAD</span></a> to
   the others.</p></dd><dt><a id="exemptionp"></a><span class="term"><code class="code">(<a class="link" href="#exemptionp"><code class="function">MT:EXEMPTIONP</code></a>
   <em class="replaceable"><code>object</code></em>)</code></span></dt><dd>Check whether the object is of type <a class="link" href="#exemption"><span class="type">MT:EXEMPTION</span></a>.
</dd><dt><a id="make-exemption"></a><span class="term"><code class="code">(<a class="link" href="#make-exemption"><code class="function">MT:MAKE-EXEMPTION</code></a>
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:NAME</code>)</code></span></dt><dd><p class="simpara">Create a new <a class="link" href="#exemption"><span class="type">MT:EXEMPTION</span></a> object.
   <code class="constant">:NAME</code> should be a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> describing the exemption (this really
   helps debugging deadlocks).</p><p class="simpara">Cf. <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_init.html"><code class="function">pthread_cond_init</code></a>.</p></dd><dt><a id="exemption-name"></a><span class="term"><code class="code">(<a class="link" href="#exemption-name"><code class="function">MT:EXEMPTION-NAME</code></a>
   <em class="replaceable"><code>exemption</code></em>)</code></span></dt><dd>Return the <em class="replaceable"><code>name</code></em> of the <em class="replaceable"><code>exemption</code></em>.
</dd><dt><a id="exemption-signal"></a><span class="term"><code class="code">(<a class="link" href="#exemption-signal"><code class="function">MT:EXEMPTION-SIGNAL</code></a>
   <em class="replaceable"><code>exemption</code></em>)</code></span></dt><dd><p class="simpara">Signal <em class="replaceable"><code>exemption</code></em> object, i.e. wake up a thread blocked
   on waiting for <em class="replaceable"><code>exemption</code></em>.</p><p class="simpara">Cf. <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_signal.html"><code class="function">pthread_cond_signal</code></a>.</p></dd><dt><a id="exemption-wait"></a><span class="term"><code class="code">(<a class="link" href="#exemption-wait"><code class="function">MT:EXEMPTION-WAIT</code></a>
   <em class="replaceable"><code>exemption</code></em> <em class="replaceable"><code>mutex</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <a class="link" href="#timeout-k" title="32.4.3. Argument :TIMEOUT"><code class="constant">:TIMEOUT</code></a> <code class="constant">:TEST</code>)</code></span></dt><dd><p class="simpara">Wait for another <a class="link" href="#thread"><span class="type">MT:THREAD</span></a> to call <a class="link" href="#exemption-signal"><code class="function">MT:EXEMPTION-SIGNAL</code></a>
   or <a class="link" href="#exemption-broadcast"><code class="function">MT:EXEMPTION-BROADCAST</code></a> on <em class="replaceable"><code>exemption</code></em>.
   <em class="replaceable"><code>mutex</code></em> should be locked by the caller; otherwise an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.
   The function releases the <em class="replaceable"><code>mutex</code></em> and waits for <em class="replaceable"><code>exemption</code></em>.
   On return <em class="replaceable"><code>mutex</code></em> is acquired again.</p><p class="simpara">When using exemptions there is always a boolean <em class="replaceable"><code>predicate</code></em> involving
   shared variables associated with each exemption wait that is true if the
   thread should proceed.</p><p class="simpara">The function waits up to <a class="link" href="#timeout-k" title="32.4.3. Argument :TIMEOUT"><code class="constant">:TIMEOUT</code></a> <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-4-4.html">seconds</a>.
   If timeout is not specified, waits forever.</p><p class="simpara">
   Returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> if <em class="replaceable"><code>exemption</code></em> was signaled and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> on timeout.</p><p>On <a class="ulink" href="http://www.opengroup.org/austin/papers/posix_faq.html" target="_top"><span class="platform">POSIX</span></a> it is possible to have
   <a class="ulink" href="http://en.wikipedia.org/wiki/Spurious_wakeup" target="_top">spurious
    wakeup</a>s, i.e., this function may return <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> even though no
   thread called <a class="link" href="#exemption-broadcast"><code class="function">MT:EXEMPTION-BROADCAST</code></a> or <a class="link" href="#exemption-signal"><code class="function">MT:EXEMPTION-SIGNAL</code></a>.
   Therefore, a common idiom for using this function is: <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_loop.html" target="_top"><code class="function">LOOP</code></a>
   :until (<em class="replaceable"><code>predicate</code></em>) :do (<a class="link" href="#exemption-wait"><code class="function">MT:EXEMPTION-WAIT</code></a> <em class="replaceable"><code>exemption</code></em> <em class="replaceable"><code>mutex</code></em>))</code></p><p class="simpara">The <code class="constant">:TEST</code> argument simplifies this. When supplied,
   <a class="link" href="#exemption-wait"><code class="function">MT:EXEMPTION-WAIT</code></a> returns when either <code class="constant">:TEST</code> <em class="replaceable"><code>predicate</code></em> is satisfied
   (always called while <em class="replaceable"><code>mutex</code></em> is held) or when <a class="link" href="#timeout-k" title="32.4.3. Argument :TIMEOUT"><code class="constant">:TIMEOUT</code></a> elapses.
   The above loop is equivalent to: <code class="code">(<a class="link" href="#exemption-wait"><code class="function">MT:EXEMPTION-WAIT</code></a> <em class="replaceable"><code>exemption</code></em>
    <em class="replaceable"><code>mutex</code></em> <code class="constant">:TEST</code> #'<em class="replaceable"><code>predicate</code></em>)</code>.
   When <code class="constant">:TEST</code> is supplied, <a class="link" href="#exemption-wait"><code class="function">MT:EXEMPTION-WAIT</code></a> returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> when <em class="replaceable"><code>exemption</code></em> was
   signaled and <code class="constant">:TEST</code> <em class="replaceable"><code>predicate</code></em> is satisfied and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> on timeout.
   </p><p class="simpara">This is the preferred and most portable way to wait on
     an exemption.</p><p class="simpara">Cf. <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_wait.html"><code class="function">pthread_cond_wait</code></a>.</p></dd><dt><a id="exemption-broadcast"></a><span class="term"><code class="code">(<a class="link" href="#exemption-broadcast"><code class="function">MT:EXEMPTION-BROADCAST</code></a>
   <em class="replaceable"><code>exemption</code></em>)</code></span></dt><dd><p class="simpara">Signal <em class="replaceable"><code>exemption</code></em> to all threads waiting for it.</p><p class="simpara">Cf. <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_cond_broadcast.html"><code class="function">pthread_cond_broadcast</code></a>.
</p></dd><dt><a id="y-or-n-p-timeout"></a><span class="term"><code class="code">(<a class="link" href="#y-or-n-p-timeout"><code class="function">MT:Y-OR-N-P-TIMEOUT</code></a>
   seconds default <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>arguments</code></em>)</code><br /></span><span class="term"><code class="code">(<a class="link" href="#y-or-n-p-timeout"><code class="function">MT:YES-OR-NO-P-TIMEOUT</code></a> seconds default <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a>
   <em class="replaceable"><code>arguments</code></em>)</code></span></dt><dd>Similar to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_y-or-n-pcm_yes-or-no-p.html" target="_top"><code class="function">Y-OR-N-P</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_y-or-n-pcm_yes-or-no-p.html" target="_top"><code class="function">YES-OR-NO-P</code></a>, but use
   <a class="link" href="#with-timeout"><code class="function">MT:WITH-TIMEOUT</code></a> to return <em class="replaceable"><code>DEFAULT</code></em> when no
   reply is given within timeout <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-4-4.html">seconds</a>.</dd><dt><a id="with-timeout"></a><span class="term"><code class="code">(<a class="link" href="#with-timeout"><code class="function">MT:WITH-TIMEOUT</code></a>
   (seconds <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> timeout-forms) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> <em class="replaceable"><code>body</code></em>)</code></span></dt><dd><p class="simpara">Execute <em class="replaceable"><code>body</code></em>. If it does not finish for up to
   <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-4-4.html">seconds</a>, it is interrupted and <em class="replaceable"><code>timeout-forms</code></em>
   are executed.</p><p class="simpara">Return the values of the last evaluated form in either
   <em class="replaceable"><code>body</code></em> or <em class="replaceable"><code>timeout-forms</code></em>.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>Since on timeout the current thread is interrupted,
    special care may be needed for ensuring proper cleanup in <em class="replaceable"><code>body</code></em>.
    See <a class="link" href="#thread-interrupt"><code class="function">MT:THREAD-INTERRUPT</code></a> and <a class="link" href="#with-deferred-interrupts"><code class="function">MT:WITH-DEFERRED-INTERRUPTS</code></a>.</p></div></dd><dt><a id="symbol-value-thread"></a><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>
   (<a class="link" href="#symbol-value-thread"><code class="function">MT:SYMBOL-VALUE-THREAD</code></a> <em class="replaceable"><code>symbol</code></em> <em class="replaceable"><code>thread</code></em>) <em class="replaceable"><code>value</code></em>)</code><br /></span><span class="term"><code class="code">(<a class="link" href="#symbol-value-thread"><code class="function">MT:SYMBOL-VALUE-THREAD</code></a> <em class="replaceable"><code>symbol</code></em> <em class="replaceable"><code>thread</code></em>)</code></span></dt><dd>Access or set the <a class="link" href="#mt-symvalue" title="32.5.2.2. Special Variable Values"><span class="emphasis"><em>Per-Thread Variable</em></span></a> value.
   When <em class="replaceable"><code>thread</code></em> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>, use the <a class="link" href="#current-thread"><code class="function">MT:CURRENT-THREAD</code></a>; if it is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, use the
   <a class="link" href="#mt-symvalue" title="32.5.2.2. Special Variable Values"><span class="emphasis"><em>Global Variable</em></span></a> binding.
   Returns two values: the <em class="replaceable"><code>symbol</code></em> binding and an indicator: <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if
   not bound in the <em class="replaceable"><code>thread</code></em>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> if bound, and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_makunbound.html" target="_top"><code class="function">MAKUNBOUND</code></a> if
   the <a class="link" href="#mt-symvalue" title="32.5.2.2. Special Variable Values"><span class="emphasis"><em>Per-Thread Variable</em></span></a> binding was removed with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_makunbound.html" target="_top"><code class="function">MAKUNBOUND</code></a>.
</dd><dt><a id="default-special-bindings"></a><span class="term"><a class="link" href="#default-special-bindings"><code class="varname">MT:*DEFAULT-SPECIAL-BINDINGS*</code></a></span></dt><dd>The default <code class="constant">:INITIAL-BINDINGS</code>
   argument of <a class="link" href="#make-thread"><code class="function">MT:MAKE-THREAD</code></a>.</dd><dt><a id="with-deferred-interrupts"></a><span class="term">
  <code class="code">(<a class="link" href="#with-deferred-interrupts"><code class="function">MT:WITH-DEFERRED-INTERRUPTS</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> <em class="replaceable"><code>body</code></em>)</code></span></dt><dd><p class="simpara">Defer thread interrupts (but <span class="strong"><strong>not</strong></span> thread
   preemption) while <em class="replaceable"><code>body</code></em> is executed.  If there is an interrupt
   while <em class="replaceable"><code>body</code></em> is run, it is queued and will be executed after
   <em class="replaceable"><code>body</code></em> finishes.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>Care is needed if waiting or blocking in <em class="replaceable"><code>body</code></em>,
    since there is no way to interrupt it (in case of a deadlock).
    The macro was added to avoid partial <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_unwind-protect.html" target="_top"><code class="function">UNWIND-PROTECT</code></a>'s cleanup
    forms evaluation in case they are interrupted with a non-local exit.
</p></div></dd><dt><a id="thread-join"></a><span class="term"><code class="code">(<a class="link" href="#thread-join"><code class="function">MT:THREAD-JOIN</code></a> <em class="replaceable"><code>thread</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   <a class="link" href="#timeout-k" title="32.4.3. Argument :TIMEOUT"><code class="constant">:TIMEOUT</code></a>)</code></span></dt><dd><p class="simpara">Wait for <em class="replaceable"><code>thread</code></em> to terminate and return two values:
  <em class="replaceable"><code>thread</code></em>'s <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_m.html#multiple_values">multiple values</a> as a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> and a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_boolean.html" target="_top"><code class="classname">BOOLEAN</code></a> indicator of whether <em class="replaceable"><code>thread</code></em>
  finished normally or has been interrupted with <a class="link" href="#thread-interrupt"><code class="function">MT:THREAD-INTERRUPT</code></a>.</p><p class="simpara">This function uses <a class="link" href="#exemption-wait"><code class="function">MT:EXEMPTION-WAIT</code></a> (and <span class="strong"><strong>not</strong></span>
  <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_join.html"><code class="function">pthread_join</code></a>), so there are no resource
  leaks normally associated with this function.</p><p class="simpara">On timeout, return <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_m.html#multiple_values">multiple values</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and <a class="link" href="#timeout-k" title="32.4.3. Argument :TIMEOUT"><code class="constant">:TIMEOUT</code></a>.</p><p class="simpara">This function can be used repeatedly on the same thread,
  so this is the usual way to access the return values of a finished
  thread.</p></dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="quickstart"></a>32.6. Quickstarting delivery with <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#quickstart-summary">32.6.1. Summary</a></span></dt><dt><span class="section"><a href="#quickstart-unix">32.6.2. Scripting with <span class="command"><strong>CLISP</strong></span></a></span></dt><dt><span class="section"><a href="#quickstart-desktop">32.6.3. Desktop Environments</a></span></dt><dt><span class="section"><a href="#quickstart-linux">32.6.4. Associating extensions with <span class="command"><strong>CLISP</strong></span> via kernel</a></span></dt></dl></div><p>This section describes three ways to turn <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> programs into
 executable programs, which can be started as quickly as executables
 written in other languages.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="quickstart-summary"></a>32.6.1. Summary</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a></span></dt><dd><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> can act as a script interpreter.
  </dd><dt><span class="term">Desktop environments such as <a class="ulink" href="http://www.kde.org/" target="_top"><span class="platform">KDE</span></a>, <a class="ulink" href="http://www.gnome.org/" target="_top"><span class="platform">Gnome</span></a>,
   <a class="ulink" href="http://www.apple.com/macosx/" target="_top"><span class="platform">Mac OS X</span></a> or <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>.</span></dt><dd>Files created with <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> can be associated with
   the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> executable so that clicking on them would make <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
   execute the appropriate code.</dd><dt><span class="term"><a class="ulink" href="https://www.kernel.org/" target="_top"><span class="platform">Linux</span></a> kernel with
   <code class="option">CONFIG_BINFMT_MISC=y</code></span></dt><dd>Associate the extensions <code class="filename">#P".fas"</code>
    and <code class="filename">#P".lisp"</code> with <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>; then you can make the
    files executable and run them from the command line.
 </dd></dl></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="quickstart-multifile"></a>Multi-file applications</h3><p>These three techniques apply to a single <code class="filename">#P".lisp"</code> or
  <code class="filename">#P".fas"</code> file.  If your application is made up of several
  <code class="filename">#P".lisp"</code> or <code class="filename">#P".fas"</code> files, you can simply concatenate them
  (using <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/cat.html"><span class="command"><strong>cat</strong></span></a>) into one file; the
  techniques then apply to that concatenated file.</p></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="quickstart-lispless"></a>Lisp-less target</h3><p>These three techniques assume that the target machine has <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
  pre-installed and thus you can deliver just your own application, not
  <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> itself.  If you want to deliver applications without assuming
  anything about your target box, you have to resort to creating
  executable <a href="impnotes.html#image" class="olink">memory image</a>s.</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="quickstart-unix"></a>32.6.2. Scripting with <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a></h3></div><div><h4 class="subtitle"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> platform only.</span></span></h4></div></div></div><p>On <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, a text file (<code class="filename">#P".fas"</code> or <code class="filename">#P".lisp"</code>) can
 be made executable by adding a first line of the form
 </p><pre class="screen">#!<em class="replaceable"><code>interpreter</code></em> [<em class="replaceable"><code>interpreter-arguments</code></em>]</pre><p>
 and using <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/chmod.html"><span class="command"><strong>chmod</strong></span></a> to make the file
 executable.</p><p><strong>OS Requirements. </strong><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> can be used as a script interpreter under the following
 conditions:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The <em class="replaceable"><code>interpreter</code></em> must be the full pathname of <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.
 The recommended path is <code class="filename">/usr/local/bin/clisp</code>,
 and if <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> is actually installed elsewhere, making
 <code class="filename">/usr/local/bin/clisp</code> be a symbolic link to the
 real <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.</li><li class="listitem">The <em class="replaceable"><code>interpreter</code></em> must be a real executable, not a script.
 Unfortunately, in the binary distributions of <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> on Solaris,
 <span class="command"><strong><a href="clisp.html#clisp" class="olink">clisp</a></strong></span> is a shell script because a <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> compiler cannot be
 assumed to be installed on this platform.  If you do have a <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>
 compiler installed, build <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> from the source yourself;
 <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/make.html"><span class="command"><strong>make install</strong></span></a> will install <span class="command"><strong><a href="clisp.html#clisp" class="olink">clisp</a></strong></span> as
 a real executable.</li><li class="listitem"><p>On some platforms, the first line which specifies the
 interpreter is limited in length:
   </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; "><li class="listitem">max. 32 characters on SunOS 4,</li><li class="listitem">max. 80 characters on HP-UX,</li><li class="listitem">max. 127 characters on <a class="ulink" href="https://www.kernel.org/" target="_top"><span class="platform">Linux</span></a>.</li></ul></div><p>
   Characters exceeding this limit are simply cut off by the system.
   At least 128 characters are accepted on Solaris, IRIX, AIX, OSF/1.
   There is no workaround: You have to keep the interpreter pathname
   and arguments short.</p></li><li class="listitem">On Solaris and HP-UX, only the first
 <em class="replaceable"><code>interpreter-arg</code></em> is passed to the <em class="replaceable"><code>interpreter</code></em>.
 In order to pass more than one option (for example, <code class="option"><a href="clisp.html#opt-memfile" class="olink">-M</a></code> and
 <code class="option"><a href="clisp.html#opt-load-comp" class="olink">-C</a></code>) to <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>, separate them with
 <a class="ulink" href="http://www.fileformat.info/info/unicode/char/00a0/" target="_top">no-break
 spaces</a> instead of normal spaces.  (But the separator between
 <em class="replaceable"><code>interpreter</code></em> and <em class="replaceable"><code>interpreter-arguments</code></em> must still be a normal space!) <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
 will split the <em class="replaceable"><code>interpreter-arguments</code></em> both at no-break spaces and at normal spaces.
</li></ul></div><p><a id="script-exec"></a><strong>Script execution. </strong></p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">The <a href="clisp.html#opt-exec-file" class="olink">script</a> should contain Lisp
   forms, except in the <code class="literal">#!</code> line.</li><li class="listitem">The file is loaded normally, through the function
   <a href="impnotes.html#loadfile" class="olink"><code class="function">LOAD</code></a> (in particular, the name of the script file, which
   is <code class="envar">$0</code> in <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/sh.html"><span class="command"><strong>/bin/sh</strong></span></a>, can be found in <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stload-pa_d-truenamest.html" target="_top"><code class="varname">*LOAD-TRUENAME*</code></a> and
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stload-pa_d-truenamest.html" target="_top"><code class="varname">*LOAD-PATHNAME*</code></a>).</li><li class="listitem">Before it is loaded, the variable <a href="impnotes.html#script-exec" class="olink"><code class="varname">EXT:*ARGS*</code></a> is bound
   to a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>s, representing the arguments given to the
   Lisp script (i.e., <code class="envar">$1</code> in <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/sh.html"><span class="command"><strong>/bin/sh</strong></span></a> becomes <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_firstcm_s_inthcm_tenth.html" target="_top"><code class="function">FIRST</code></a>
     <a href="impnotes.html#script-exec" class="olink"><code class="varname">EXT:*ARGS*</code></a>)</code> etc).</li><li class="listitem">The standard <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> i/o facilities (see <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/stdio.h.html">&lt;<code class="filename">stdio.h</code>&gt;</a>)
    are used: <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-INPUT*</code></a> is bound to <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/stdin.html"><code class="varname">stdin</code></a>,
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-OUTPUT*</code></a> to <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/stdout.html"><code class="varname">stdout</code></a>, and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*ERROR-OUTPUT*</code></a> to <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/stderr.html"><code class="varname">stderr</code></a>.
    Note <a class="xref" href="#dribble-script" title="25.2.11.1. Scripting and DRIBBLE">Section 25.2.11.1, “Scripting and <code class="function">DRIBBLE</code>”</a>.</li><li class="listitem">The <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#continuable">continuable</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>s will be turned into <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_warning.html" target="_top"><code class="classname">WARNING</code></a>s
   (using <a href="impnotes.html#appease-cerrors" class="olink"><code class="function">EXT:APPEASE-CERRORS</code></a>).</li><li class="listitem">Non-<a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#continuable">continuable</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>s and <span class="keycap"><strong>Control</strong></span>+<span class="keysym">C</span> interrupts will
   terminate the execution of the Lisp script with an error status
   (using <a href="impnotes.html#exit-on-error" class="olink"><code class="function">EXT:EXIT-ON-ERROR</code></a>).</li><li class="listitem">If you wish the script's contents to be compiled
    during loading, add <code class="option"><a href="clisp.html#opt-load-comp" class="olink">-C</a></code> to the <em class="replaceable"><code>interpreter-arguments</code></em>.
</li></ul></div><p><a id="script-bad"></a><strong>If nothing works. </strong>Another, quite inferior, alternative is to put the following into a file:
</p><pre class="programlisting">
#!<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/sh.html"><span class="command"><strong>/bin/sh</strong></span></a>
exec <span class="command"><strong><a href="clisp.html#clisp" class="olink">clisp</a></strong></span> &lt;&lt;EOF
(lisp-form)
(another-lisp-form)
(yet-another-lisp-form)
EOF
</pre><p>
The problem with this approach is that the return values of each form
will be printed to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-OUTPUT*</code></a>.
Another problem is that no user input will be available.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="quickstart-desktop"></a>32.6.3. Desktop Environments</h3></div><div><h4 class="subtitle"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>, <a class="ulink" href="http://www.gnome.org/" target="_top"><span class="platform">Gnome</span></a>, <a class="ulink" href="http://www.kde.org/" target="_top"><span class="platform">KDE</span></a>, <a class="ulink" href="http://www.apple.com/macosx/" target="_top"><span class="platform">Mac OS X</span></a>
  desktop platforms only.</span></span></h4></div></div></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="quickstart-desktop-win32"></a>Notations</h3><p>Although we use <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>-specific notation, these techniques work
 on other desktop environments as well.</p></div><p>There are two different ways to make <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
 <span class="quote">“<span class="quote">executables</span>”</span> on desktop platforms.</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">Associate the <code class="filename">#P".mem"</code> extension with
   <span class="command"><strong>c:\clisp\clisp.exe <code class="option"><a href="clisp.html#opt-memfile" class="olink">-M</a></code> "%s"</strong></span>.
  </li><li class="listitem">Associate the <code class="filename">#P".fas"</code> extension with
   <span class="command"><strong>c:\clisp\clisp.exe <code class="option"><a href="clisp.html#opt-init" class="olink">-i</a></code> "%s"</strong></span>
    Alternatively, you may want to have a function
    <code class="function">main</code> in your <code class="filename">#P".fas"</code> files and associate
    the <code class="filename">#P".fas"</code> extension with <span class="command"><strong>c:\clisp\clisp.exe <code class="option"><a href="clisp.html#opt-init" class="olink">-i</a></code>
     %s <code class="option"><a href="clisp.html#opt-exec-expr" class="olink">-x</a></code> (main)</strong></span>.
  </li></ol></div><p>Then clicking on the compiled lisp file (with <code class="filename">#P".fas"</code>
 extension) will load the file (thus executing all the code in the
 file), while the clicking on a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a href="impnotes.html#image" class="olink">memory image</a> (with <code class="filename">#P".mem"</code>
 extension) will start <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> with the given <a href="impnotes.html#image" class="olink">memory image</a>.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>On <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>, <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> is distributed with a file
 <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/install.bat"><code class="filename">src/install.bat</code></a>, which
 runs <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/install.lisp"><code class="filename">src/install.lisp</code></a> to create a
 file <code class="filename">clisp.lnk</code> on your desktop and also associates
 <code class="filename">#P".fas"</code>, <code class="filename">#P".lisp"</code>, and <code class="filename">#P".mem"</code> files with <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="quickstart-linux"></a>32.6.4. Associating extensions with <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> via kernel</h3></div><div><h4 class="subtitle"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="https://www.kernel.org/" target="_top"><span class="platform">Linux</span></a> platforms only.
 </span></span></h4></div></div></div><p>You have to build your kernel with
 <code class="option">CONFIG_BINFMT_MISC=y</code> and
 <code class="option">CONFIG_PROC_FS=y</code>.  Then you will have a
 <code class="filename">/proc/sys/fs/binfmt_misc/</code> directory and you will
 be able to do (as <code class="literal">root</code>; you might want to put
 these lines into <code class="filename">/etc/rc.d/rc.local</code>):

</p><pre class="screen"><strong><code class="prompt">#</code></strong> echo ":CLISP:E::fas::/usr/local/bin/clisp:" &gt;&gt; /proc/sys/fs/binfmt_misc/register
<strong><code class="prompt">#</code></strong> echo ":CLISP:E::lisp::/usr/local/bin/clisp:" &gt;&gt; /proc/sys/fs/binfmt_misc/register</pre><p>Then you can do the following:
</p><pre class="screen"><strong><code class="prompt">$</code></strong> cat &lt;&lt; EOF &gt; hello.lisp
(print "hello, world!")
EOF
<strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp.html#clisp" class="olink">clisp</a></strong></span> <code class="option"><a href="clisp.html#opt-compile" class="olink">-c</a></code> hello.lisp
;; Compiling file hello.lisp ...
;; Wrote file hello.fas
0 errors, 0 warnings
<strong><code class="prompt">$</code></strong> chmod +x hello.fas
<strong><code class="prompt">$</code></strong> hello.fas

"hello, world!"</pre><p>Please read
 <a class="ulink" href="https://www.kernel.org/doc/Documentation/admin-guide/binfmt-misc.rst" target="_top">
  <code class="filename">/usr/src/linux/Documentation/binfmt_misc.txt</code></a>
 for details.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="shell"></a>32.7. Shell, Pipes and Printing</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#exec">32.7.1. Shell</a></span></dt><dt><span class="section"><a href="#pipe">32.7.2. Pipes</a></span></dt><dt><span class="section"><a href="#hardcopy">32.7.3. Printing</a></span></dt></dl></div><p>This section describes how <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> can invoke external
 executables and communicate with the resulting processes.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="exec"></a>32.7.1. Shell</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> platform only.</span></span></span></dt><dd><code class="code">(<a class="link" href="#exec" title="32.7.1. Shell"><code class="function">EXT:EXECUTE</code></a> <em class="replaceable"><code>program</code></em>
       <em class="replaceable"><code>arg<sub>1</sub></code></em>
       <em class="replaceable"><code>arg<sub>2</sub></code></em> ...)</code>
   executes an external program.
   Its name is <em class="replaceable"><code>program</code></em> (a full pathname).
   It is given the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>s <em class="replaceable"><code>arg<sub>1</sub></code></em>,
   <em class="replaceable"><code>arg<sub>2</sub></code></em>, ... as arguments.
 </dd><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platforms only.</span></span></span></dt><dd><p class="simpara"><code class="code">(<a href="impnotes.html#exec" class="olink"><code class="function">EXT:SHELL</code></a> [<em class="replaceable"><code>command</code></em>])</code>
   calls the operating system's shell.</p><p class="simpara"><code class="code">(<a href="impnotes.html#exec" class="olink"><code class="function">EXT:SHELL</code></a>)</code> calls the shell for interactive use.</p><p><code class="code">(<a href="impnotes.html#exec" class="olink"><code class="function">EXT:SHELL</code></a> <em class="replaceable"><code>command</code></em>)</code> calls the shell
   only for execution of the one given <em class="replaceable"><code>command</code></em>, which can be a
   complex expression: </p><pre class="programlisting">
(<a href="impnotes.html#exec" class="olink"><code class="function">EXT:SHELL</code></a> "for x in 1 2 3; do echo $x; done")
1
2
3
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></code></pre><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> platform only.</span></span></span></dt><dd><a class="link" href="#exec" title="32.7.1. Shell"><code class="function">EXT:EXECUTE</code></a> is called on the value of the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html">environment variable</a>
  <code class="envar">SHELL</code> if used interactively;
  <span class="command"><strong><a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/sh.html"><span class="command"><strong>/bin/sh</strong></span></a> -c <em class="replaceable"><code>command</code></em></strong></span> if used non-interactively.
</dd><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platform only.</span></span></span></dt><dd><a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=CreateProcess"><code class="function">CreateProcess</code></a> is
 called on <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_or.html" target="_top"><code class="function">OR</code></a> <em class="replaceable"><code>command</code></em> (<a class="link" href="#getenv" title="32.8. Operating System Environment"><code class="function">EXT:GETENV</code></a> <code class="envar">COMSPEC</code>))</code>
</dd></dl></div></dd><dt><a id="run-prog"></a><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platforms only.</span></span></span></dt><dd><p class="simpara">The functions <a class="link" href="#run-prog"><code class="function">EXT:RUN-SHELL-COMMAND</code></a> and <a class="link" href="#run-prog"><code class="function">EXT:RUN-PROGRAM</code></a> are the
   general interface to <a href="impnotes.html#exec" class="olink"><code class="function">EXT:SHELL</code></a> and the above:</p><p class="simpara"><code class="code">(<a class="link" href="#run-prog"><code class="function">EXT:RUN-SHELL-COMMAND</code></a> <em class="replaceable"><code>command</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    <code class="constant">:MAY-EXEC</code> <code class="constant">:INDIRECTP</code>
    <code class="constant">:INPUT</code> <code class="constant">:OUTPUT</code> <code class="constant">:IF-OUTPUT-EXISTS</code> <code class="constant">:WAIT</code>)</code>
   runs a shell command (including shell built-in commands,
   like <span class="command"><strong>DIR</strong></span> on <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>
   and <span class="command"><strong>for/do/done</strong></span> on <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>).</p><p class="simpara"><code class="code">(<a class="link" href="#run-prog"><code class="function">EXT:RUN-PROGRAM</code></a> <em class="replaceable"><code>program</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    <code class="constant">:MAY-EXEC</code> <code class="constant">:INDIRECTP</code>
    <code class="constant">:ARGUMENTS</code> <code class="constant">:INPUT</code> <code class="constant">:OUTPUT</code> <code class="constant">:IF-OUTPUT-EXISTS</code> <code class="constant">:WAIT</code>)</code>
   runs an external program.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>command</code></em></span></dt><dd>the shell command.</dd><dt><span class="term"><em class="replaceable"><code>program</code></em></span></dt><dd>the program.  The directories listed in the
     <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html">environment variable</a> <code class="envar">PATH</code> will be searched for it.
    </dd><dt><span class="term"><code class="constant">:ARGUMENTS</code></span></dt><dd>a list of arguments (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>s) that are given
      to the program.</dd><dt><span class="term"><code class="constant">:INPUT</code></span></dt><dd>where the program's input is to come from: either
     <code class="constant">:TERMINAL</code> (<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/stdin.html"><code class="varname">stdin</code></a>, the default) or
     <code class="constant">:STREAM</code> (a Lisp <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> to be created) or
     a <a class="link" href="#path-des" title="Pathname Designators">pathname designator</a> (an input file) or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> (no input at all).
   </dd><dt><span class="term"><code class="constant">:OUTPUT</code></span></dt><dd>where the program's output is to be sent to: either
     <code class="constant">:TERMINAL</code> (<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/stdout.html"><code class="varname">stdout</code></a>, the default) or
     <code class="constant">:STREAM</code> (a Lisp <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> to be created) or
     a <a class="link" href="#path-des" title="Pathname Designators">pathname designator</a> (an output file) or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> (ignore the output).
   </dd><dt><span class="term"><code class="constant">:IF-OUTPUT-EXISTS</code></span></dt><dd>what to do if the <code class="constant">:OUTPUT</code> file already exists.
     The possible values are <code class="constant">:OVERWRITE</code>, <code class="constant">:APPEND</code>, <code class="constant">:ERROR</code>,
     with the same meaning as for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_open.html" target="_top"><code class="function">OPEN</code></a>. The default is <code class="constant">:OVERWRITE</code>.
    </dd><dt><span class="term"><code class="constant">:WAIT</code></span></dt><dd>whether to wait for program termination or not
     (this is useful when no i/o to the process is needed);
     the default is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>, i.e., synchronous execution.
    </dd><dt><span class="term"><code class="constant">:MAY-EXEC</code></span></dt><dd>pass <span class="command"><strong>exec</strong></span> to the underlying
    shell (<a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> only).</dd><dt><span class="term"><code class="constant">:INDIRECTP</code></span></dt><dd>use a shell to run the command, e.g.,
    <code class="code">(<a class="link" href="#run-prog"><code class="function">EXT:RUN-PROGRAM</code></a> "dir" :indirectp <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>)</code>
    will run the shell built-in command <span class="command"><strong>DIR</strong></span>.
    This argument defaults to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> for <a class="link" href="#run-prog"><code class="function">EXT:RUN-SHELL-COMMAND</code></a> and to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> for <a class="link" href="#run-prog"><code class="function">EXT:RUN-PROGRAM</code></a>.
    (<a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> only).</dd></dl></div><p>If <code class="constant">:STREAM</code> was specified for <code class="constant">:INPUT</code> or <code class="constant">:OUTPUT</code>, a Lisp
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> is returned.
 If <code class="constant">:STREAM</code> was specified for both <code class="constant">:INPUT</code> and <code class="constant">:OUTPUT</code>, three
 Lisp <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s are returned, as for the function <a class="link" href="#pipe" title="32.7.2. Pipes"><code class="function">EXT:MAKE-PIPE-IO-STREAM</code></a>.
 Otherwise, the return value depends on the process termination status:
 if it exited on a signal or a core-dump,
 the signal number is returned as a negative <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>,
 else, if it ended normally with 0 exit status, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> is returned;
 otherwise, the status is returned as a positive <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>.</p><p>This use of <a class="link" href="#run-prog"><code class="function">EXT:RUN-PROGRAM</code></a> can cause
 <a class="link" href="#deadlock" title="Warning">deadlocks</a>, see <a class="link" href="#pipe" title="32.7.2. Pipes"><code class="function">EXT:MAKE-PIPE-IO-STREAM</code></a>.</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="pipe"></a>32.7.2. Pipes</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platforms only.</span></span></span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">(<a class="link" href="#pipe" title="32.7.2. Pipes"><code class="function">EXT:MAKE-PIPE-INPUT-STREAM</code></a> <em class="replaceable"><code>command</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <a class="link" href="#eltype"><code class="constant">:ELEMENT-TYPE</code></a>
    <a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a> <a class="link" href="#buffered"><code class="constant">:BUFFERED</code></a>)</code></span></dt><dd>returns an <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_i.html#input">input</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> that will supply the output
   from the execution of the given operating system command.
</dd><dt><span class="term"><code class="code">(<a class="link" href="#pipe" title="32.7.2. Pipes"><code class="function">EXT:MAKE-PIPE-OUTPUT-STREAM</code></a> <em class="replaceable"><code>command</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <a class="link" href="#eltype"><code class="constant">:ELEMENT-TYPE</code></a>
   <a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a> <a class="link" href="#buffered"><code class="constant">:BUFFERED</code></a>)</code></span></dt><dd>returns an <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_o.html#output">output</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> that will pass its output as
   input to the execution of the given operating system command.
</dd><dt><span class="term"><code class="code">(<a class="link" href="#pipe" title="32.7.2. Pipes"><code class="function">EXT:MAKE-PIPE-IO-STREAM</code></a> <em class="replaceable"><code>command</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <a class="link" href="#eltype"><code class="constant">:ELEMENT-TYPE</code></a>
   <a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a> <a class="link" href="#buffered"><code class="constant">:BUFFERED</code></a>)</code></span></dt><dd><p class="simpara">returns three values.
  The <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#primary_value">primary value</a> is a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_b.html#bidirectional">bidirectional</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> that will simultaneously pass its output
  as input to the execution of the given operating system command and
  supply the output from this command as input.
  The second and third value are the <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_i.html#input">input</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> and the <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_o.html#output">output</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> that
  make up the <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_b.html#bidirectional">bidirectional</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>, respectively.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>These three streams must be closed individually, see
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Issues/iss052.html" target="_top">CLOSE-CONSTRUCTED-STREAM:ARGUMENT-STREAM-ONLY</a>.</p></div><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="deadlock"></a>Warning</h3><p>Improper use of this function
   can lead to <span class="emphasis"><em>deadlocks</em></span>.
   Use it at your own risk!</p><p>A deadlock occurs if the command and your Lisp program either
   both try to read from each other at the same time or both try to
   write to each other at the same time.</p><p>To avoid deadlocks, it is recommended that you fix a
   protocol between the command and your program and avoid any hidden
   buffering: use <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-char.html" target="_top"><code class="function">READ-CHAR</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-char-no-hang.html" target="_top"><code class="function">READ-CHAR-NO-HANG</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_listen.html" target="_top"><code class="function">LISTEN</code></a>,
   <a class="link" href="#so-status"><code class="function">SOCKET:SOCKET-STATUS</code></a> instead of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-line.html" target="_top"><code class="function">READ-LINE</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_readcm_re_g-whitespace.html" target="_top"><code class="function">READ</code></a> on the input side, and
   complete every output operation by a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_finish-ou_clear-output.html" target="_top"><code class="function">FINISH-OUTPUT</code></a>.
   The same precautions must apply to the called command as well.
</p></div></dd></dl></div></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="hardcopy"></a>32.7.3. Printing</h3></div></div></div><p>The macro
 <strong class="first"><em class="firstterm"><a class="link" href="#hardcopy" title="32.7.3. Printing"><code class="function">EXT:WITH-OUTPUT-TO-PRINTER</code></a><a id="with-print" class="indexterm"></a></em></strong>:
</p><pre class="programlisting">
(<a class="link" href="#hardcopy" title="32.7.3. Printing"><code class="function">EXT:WITH-OUTPUT-TO-PRINTER</code></a> (<em class="replaceable"><code>variable</code></em> [<a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a>])
  {<em class="replaceable"><code>declaration</code></em>}*
  {<em class="replaceable"><code>form</code></em>}*)
</pre><p>
 binds the variable <em class="replaceable"><code>variable</code></em> to an <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_o.html#output">output</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>
 that sends its output to the printer.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="getenv"></a>32.8. Operating System Environment</h2></div></div></div><p>Most modern operating systems support <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html">environment variable</a>s that associate
 strings (<span class="quote">“<span class="quote">variables</span>”</span>) with other strings
 (<span class="quote">“<span class="quote">values</span>”</span>).  These variables are somewhat similar to the
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/dec_special.html" target="_top"><code class="literal">SPECIAL</code></a> variables in <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a>: their values are inherited by the
 processes from their parent process.</p><p>You can access your OS <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html">environment variable</a>s using the function
<code class="code">(<a class="link" href="#getenv" title="32.8. Operating System Environment"><code class="function">EXT:GETENV</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>string</code></em>)</code>,
where <em class="replaceable"><code>string</code></em> is the name of the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html">environment variable</a>.
When <em class="replaceable"><code>string</code></em> is omitted or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, all the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html">environment variable</a>s and their values
are returned in an <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_a.html#association_list">association list</a>.</p><p>You can change the value of existing <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html">environment variable</a>s or create new ones
 using <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="link" href="#getenv" title="32.8. Operating System Environment"><code class="function">EXT:GETENV</code></a> <em class="replaceable"><code>string</code></em>) <em class="replaceable"><code>new-value</code></em>)</code>.</p><p>Use <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="link" href="#getenv" title="32.8. Operating System Environment"><code class="function">EXT:GETENV</code></a> <em class="replaceable"><code>string</code></em>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>)</code> to remove an
 <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html">environment variable</a> <em class="replaceable"><code>string</code></em>.</p></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="ext-modules"></a>Chapter 33. Extensions Implemented as Modules</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#asdf">33.1. A System Definition Facility</a></span></dt><dt><span class="section"><a href="#syscalls">33.2. System Calls</a></span></dt><dd><dl><dt><span class="section"><a href="#neworking">33.2.1. Networking</a></span></dt><dt><span class="section"><a href="#file-system">33.2.2. File system</a></span></dt><dt><span class="section"><a href="#user-group">33.2.3. Users and Groups</a></span></dt><dt><span class="section"><a href="#sysinfo">33.2.4. System Information</a></span></dt><dt><span class="section"><a href="#posix-math">33.2.5. Mathematical functions</a></span></dt><dt><span class="section"><a href="#encryption">33.2.6. Encryption</a></span></dt><dt><span class="section"><a href="#sys-log">33.2.7. Syslog</a></span></dt><dt><span class="section"><a href="#processes">33.2.8. Processes</a></span></dt><dt><span class="section"><a href="#accounting">33.2.9. Accounting</a></span></dt><dt><span class="section"><a href="#posix-time">33.2.10. Time and Data Conversion</a></span></dt><dt><span class="section"><a href="#strverscmp">33.2.11. String comparision</a></span></dt><dt><span class="section"><a href="#wildcard">33.2.12. Wildcard Matching</a></span></dt><dt><span class="section"><a href="#mk-xterm-io">33.2.13. XTerm</a></span></dt><dt><span class="section"><a href="#stdio">33.2.14. Standard file input and output</a></span></dt><dt><span class="section"><a href="#errno">33.2.15. Error handling</a></span></dt><dt><span class="section"><a href="#misc">33.2.16. Miscellanea</a></span></dt></dl></dd><dt><span class="section"><a href="#i18n-mod">33.3. Internationalization of User Programs</a></span></dt><dd><dl><dt><span class="section"><a href="#ggettext">33.3.1. The GNU gettext</a></span></dt><dd><dl><dt><span class="section"><a href="#domain">33.3.1.1. Domain</a></span></dt><dt><span class="section"><a href="#category">33.3.1.2. Category</a></span></dt><dt><span class="section"><a href="#i18n-example">33.3.1.3. Internationalization Example</a></span></dt></dl></dd><dt><span class="section"><a href="#i18n-locale">33.3.2. Locale</a></span></dt></dl></dd><dt><span class="section"><a href="#regexp-mod">33.4. POSIX Regular Expressions</a></span></dt><dt><span class="section"><a href="#readline-mod">33.5. Advanced Readline and History Functionality</a></span></dt><dt><span class="section"><a href="#gdbm">33.6. GDBM - The GNU database manager</a></span></dt><dt><span class="section"><a href="#berkeley-db">33.7. Berkeley DB access</a></span></dt><dd><dl><dt><span class="section"><a href="#bdb-objects">33.7.1. Berkeley-DB Objects</a></span></dt><dt><span class="section"><a href="#bdb-close">33.7.2. Closing handles</a></span></dt><dt><span class="section"><a href="#bdb-db-environment">33.7.3. Database Environment</a></span></dt><dt><span class="section"><a href="#bdb-environment-config">33.7.4. Environment Configuration</a></span></dt><dt><span class="section"><a href="#bdb-operations">33.7.5. Database Operations</a></span></dt><dt><span class="section"><a href="#bdb-db-config">33.7.6. Database Configuration</a></span></dt><dt><span class="section"><a href="#bdb-cursor">33.7.7. Database Cursor Operations</a></span></dt><dt><span class="section"><a href="#bdb-lock">33.7.8. Lock Subsystem</a></span></dt><dt><span class="section"><a href="#bdb-log">33.7.9. Log Subsystem</a></span></dt><dd><dl><dt><span class="section"><a href="#bdb-log-cursor">33.7.9.1. Log Cursor Operations</a></span></dt><dt><span class="section"><a href="#bdb-log-seq">33.7.9.2. Log Sequence Numbers</a></span></dt></dl></dd><dt><span class="section"><a href="#bdb-mem-pool">33.7.10. Memory Pool Subsystem</a></span></dt><dt><span class="section"><a href="#bdb-replication">33.7.11. Replication</a></span></dt><dt><span class="section"><a href="#bdb-sequences">33.7.12. Sequences</a></span></dt><dt><span class="section"><a href="#bdb-transaction">33.7.13. Transaction Subsystem</a></span></dt></dl></dd><dt><span class="section"><a href="#dir-key">33.8. Directory Access</a></span></dt><dt><span class="section"><a href="#postgresql">33.9. PostgreSQL Database Access</a></span></dt><dt><span class="section"><a href="#oracle">33.10. Oracle Interface</a></span></dt><dd><dl><dt><span class="section"><a href="#ora-functionality">33.10.1. Functions and Macros in   package <strong class="package"><span class="quote">“<span class="quote">ORACLE</span>”</span></strong></a></span></dt><dt><span class="section"><a href="#ora-example">33.10.2. Oracle Example</a></span></dt><dt><span class="section"><a href="#ora-config">33.10.3. Oracle Configuration</a></span></dt><dt><span class="section"><a href="#ora-build">33.10.4. Building the Oracle Interface</a></span></dt></dl></dd><dt><span class="section"><a href="#libsvm">33.11. LibSVM Interface</a></span></dt><dd><dl><dt><span class="section"><a href="#libsvm-types">33.11.1. Types</a></span></dt><dt><span class="section"><a href="#libsvm-output">33.11.2. Output</a></span></dt><dt><span class="section"><a href="#libsvm-functions">33.11.3. Functions</a></span></dt><dd><dl><dt><span class="section"><a href="#libsvm-functions-problem">33.11.3.1. Functions related to <span class="type">problem</span></a></span></dt><dt><span class="section"><a href="#libsvm-functions-model">33.11.3.2. Functions related to <span class="type">model</span></a></span></dt><dt><span class="section"><a href="#libsvm-functions-parameter">33.11.3.3. Functions related to <span class="type">parameter</span></a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="#pari">33.12. Computer Algebra System PARI</a></span></dt><dt><span class="section"><a href="#matlab">33.13. Matlab Interface</a></span></dt><dt><span class="section"><a href="#netica">33.14. Netica Interface</a></span></dt><dt><span class="section"><a href="#pcre">33.15. Perl Compatible Regular Expressions</a></span></dt><dt><span class="section"><a href="#zlib">33.16. Interface to zlib</a></span></dt><dt><span class="section"><a href="#rawsock">33.17. Raw Socket Access</a></span></dt><dd><dl><dt><span class="section"><a href="#rawsock-intro">33.17.1. Introduction</a></span></dt><dt><span class="section"><a href="#rawsock-func">33.17.2. Single System Call Functions</a></span></dt><dt><span class="section"><a href="#rawsock-args">33.17.3. Common arguments</a></span></dt><dd><dl><dt><span class="section"><a href="#rawsock-plat-dep-constants">33.17.3.1. Platform-dependent Keywords</a></span></dt></dl></dd><dt><span class="section"><a href="#rawsock-return">33.17.4. Return Values</a></span></dt><dt><span class="section"><a href="#rawsock-not-implemented">33.17.5. Not Implemented</a></span></dt><dt><span class="section"><a href="#rawsock-errors">33.17.6. Errors</a></span></dt><dt><span class="section"><a href="#rawsock-high-level">33.17.7. High-Level Functions</a></span></dt></dl></dd><dt><span class="section"><a href="#fastcgi">33.18. The FastCGI Interface</a></span></dt><dd><dl><dt><span class="section"><a href="#fcgi-overview">33.18.1. Overview of FastCGI</a></span></dt><dt><span class="section"><a href="#fcgi-functionality">33.18.2. Functions in Package <strong class="package"><span class="quote">“<span class="quote">FASTCGI</span>”</span></strong></a></span></dt><dt><span class="section"><a href="#fcgi-example">33.18.3. FastCGI Example</a></span></dt><dt><span class="section"><a href="#fcgi-build">33.18.4. Building and configuring the   FastCGI Interface</a></span></dt></dl></dd><dt><span class="section"><a href="#dbus">33.19. Interface to D-Bus</a></span></dt><dt><span class="section"><a href="#gtk">33.20. GTK Interface</a></span></dt><dd><dl><dt><span class="section"><a href="#gtk-hi">33.20.1. High-level functions</a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="asdf"></a>33.1. A System Definition Facility</h2></div></div></div><p>This module offers a system definition facility (similar to <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/make.html"><span class="command"><strong>make</strong></span></a>).
It is based on <a class="ulink" href="http://common-lisp.net/project/asdf/" target="_top"><code class="function">asdf</code></a> 3.2.0.</p><p>Additionally, it hooks into <a href="impnotes.html#require" class="olink"><code class="function">REQUIRE</code></a> using <a class="link" href="#module-providers" title="24.3.3. User variable CUSTOM::*MODULE-PROVIDER-FUNCTIONS*"><code class="varname">CUSTOM::*MODULE-PROVIDER-FUNCTIONS*</code></a>.
This way, requiring a module causes <a class="ulink" href="http://common-lisp.net/project/asdf/" target="_top"><code class="function">asdf</code></a> to load the corresponding system.</p><p>When this module is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a> contains the symbols
</p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="constant">:ASDF3.2</code></td></tr><tr><td><code class="constant">:ASDF3.1</code></td></tr><tr><td><code class="constant">:ASDF3</code></td></tr><tr><td><code class="constant">:ASDF2</code></td></tr><tr><td><code class="constant">:ASDF</code></td></tr><tr><td><code class="constant">:ASDF-PACKAGE-SYSTEM</code></td></tr></table><p>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="syscalls"></a>33.2. System Calls</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#neworking">33.2.1. Networking</a></span></dt><dt><span class="section"><a href="#file-system">33.2.2. File system</a></span></dt><dt><span class="section"><a href="#user-group">33.2.3. Users and Groups</a></span></dt><dt><span class="section"><a href="#sysinfo">33.2.4. System Information</a></span></dt><dt><span class="section"><a href="#posix-math">33.2.5. Mathematical functions</a></span></dt><dt><span class="section"><a href="#encryption">33.2.6. Encryption</a></span></dt><dt><span class="section"><a href="#sys-log">33.2.7. Syslog</a></span></dt><dt><span class="section"><a href="#processes">33.2.8. Processes</a></span></dt><dt><span class="section"><a href="#accounting">33.2.9. Accounting</a></span></dt><dt><span class="section"><a href="#posix-time">33.2.10. Time and Data Conversion</a></span></dt><dt><span class="section"><a href="#strverscmp">33.2.11. String comparision</a></span></dt><dt><span class="section"><a href="#wildcard">33.2.12. Wildcard Matching</a></span></dt><dt><span class="section"><a href="#mk-xterm-io">33.2.13. XTerm</a></span></dt><dt><span class="section"><a href="#stdio">33.2.14. Standard file input and output</a></span></dt><dt><span class="section"><a href="#errno">33.2.15. Error handling</a></span></dt><dt><span class="section"><a href="#misc">33.2.16. Miscellanea</a></span></dt></dl></div><p>The <a class="link" href="#syscalls" title="33.2. System Calls"><strong class="package"><span class="quote">“<span class="quote">POSIX</span>”</span></strong></a> module makes some system calls available from lisp.
 Not all of these system calls are actually <a class="ulink" href="http://www.opengroup.org/austin/papers/posix_faq.html" target="_top"><span class="platform">POSIX</span></a>, so this package has a
 nickname <strong class="package"><span class="quote">“<span class="quote">OS</span>”</span></strong>.  If the package prefix is
 not specified below, the symbol resides in this package.</p><p>This module is present in the <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>base</strong></span></a> <a href="impnotes.html#linkset" class="olink">linking set</a> by default.</p><p>When this module is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a>
 contains the symbol <code class="constant">:SYSCALLS</code>.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="neworking"></a>33.2.1. Networking</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><a id="resolve-host"></a><span class="term"><code class="code">(<a class="link" href="#resolve-host"><code class="function">POSIX:RESOLVE-HOST-IPADDR</code></a>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>host</code></em>)</code></span></dt><dd><p>Returns the <span class="type">HOSTENT</span> structure:
   </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="structfield"><code>name</code></em></span></dt><dd>host name</dd><dt><span class="term"><em class="structfield"><code>aliases</code></em></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of aliases</dd><dt><span class="term"><em class="structfield"><code>addr-list</code></em></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of <a class="rfc" href="http://www.ietf.org/rfc/rfc791.txt"><code><span class="command"><strong>IP</strong></span></code></a> addresses as dotted quads (for IPv4)
       or coloned octets (for IPv6)</dd><dt><span class="term"><em class="structfield"><code>addrtype</code></em></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> address type (IPv4 or IPv6)
   </dd></dl></div><p>
   When <em class="replaceable"><code>host</code></em> is omitted or <code class="constant">:DEFAULT</code>, return the data for the
   current host. When <em class="replaceable"><code>host</code></em> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, all the
   host database is returned as a list (this would be the contents of the
   <code class="filename">/etc/hosts</code> file on a <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> system or
   <code class="filename">${windir}/system32/etc/hosts</code> on a <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> system).
  </p><p class="simpara">This is an interface
   to <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/gethostent.html"><code class="function">gethostent</code></a>,
   <a class="bsd" href="http://www.freebsd.org/cgi/man.cgi?query=gethostbyname"><code class="function">gethostbyname</code></a>,
   and <a class="bsd" href="http://www.freebsd.org/cgi/man.cgi?query=gethostbyaddr"><code class="function">gethostbyaddr</code></a>.</p></dd><dt><a id="service"></a><span class="term"><code class="code">(OS:SERVICE <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
    <em class="replaceable"><code>service-name</code></em> <em class="replaceable"><code>protocol</code></em>)</code></span></dt><dd><p class="simpara">A convenience function for looking up a port given
   the service name, such as <span class="quote">“<span class="quote">WWW</span>”</span> or <span class="quote">“<span class="quote">FTP</span>”</span>.
   It returns the <span class="type">SERVICE</span> structure
   (name, list of aliases, port, protocol) for the given
   <em class="replaceable"><code>service-name</code></em> and <em class="replaceable"><code>protocol</code></em>,
   or all services as a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> if <em class="replaceable"><code>service-name</code></em>
   is missing or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</p><p class="simpara">This is an interface
   to <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getservent.html"><code class="function">getservent</code></a>,
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getservbyname.html"><code class="function">getservbyname</code></a>,
   and <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getservbyport.html"><code class="function">getservbyport</code></a>.</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="file-system"></a>33.2.2. File system</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><a id="file-stat"></a><span class="term"><code class="code">(POSIX:FILE-STAT
    <em class="replaceable"><code>pathname</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>link-p</code></em>)</code></span></dt><dd><p>Return the <span class="type">FILE-STAT</span> structure.
   <em class="replaceable"><code>pathname</code></em> can be a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>, a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_pathname.html" target="_top"><code class="classname">PATHNAME</code></a>, a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> or a
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_number.html" target="_top"><code class="classname">NUMBER</code></a> (on a <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> system, meaning <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a>).
   The first slot of the structure returned is the string or the
   number on which <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/stat.html"><code class="function">stat</code></a>,
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fstat.html"><code class="function">fstat</code></a>,
   or <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/lstat.html"><code class="function">lstat</code></a> was called.
   The other slots are numbers, members of the <span class="type">struct stat</span>:
    </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="structfield"><code>dev</code></em></span></dt><dd>Device ID of device containing file.
     </dd><dt><span class="term"><em class="structfield"><code>ino</code></em></span></dt><dd>File serial number.
     </dd><dt><span class="term"><em class="structfield"><code>mode</code></em></span></dt><dd>Mode of file.
     </dd><dt><span class="term"><em class="structfield"><code>nlink</code></em></span></dt><dd>Number of hard links to the file.
     </dd><dt><span class="term"><em class="structfield"><code>uid</code></em></span></dt><dd>User ID of file.
     </dd><dt><span class="term"><em class="structfield"><code>gid</code></em></span></dt><dd>Group ID of file.
     </dd><dt><span class="term"><em class="structfield"><code>rdev</code></em></span></dt><dd>Device ID (if file is character or block
        special).</dd><dt><span class="term"><em class="structfield"><code>size</code></em></span></dt><dd>For regular files, the file size in bytes.
        For symbolic links, the length in bytes of the pathname contained
        in the symbolic link.
        For a shared memory object, the length in bytes.
        For a typed memory object, the length in bytes.
        For other file types, the use of this field is unspecified.
     </dd><dt><span class="term"><em class="structfield"><code>atime</code></em></span></dt><dd><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-4-2.html">universal time</a> of last access.
     </dd><dt><span class="term"><em class="structfield"><code>mtime</code></em></span></dt><dd><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-4-2.html">universal time</a> of last data modification.
     </dd><dt><span class="term"><em class="structfield"><code>ctime</code></em></span></dt><dd><a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-4-2.html">universal time</a> of last status change
        (on <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> - creation time).</dd><dt><span class="term"><em class="structfield"><code>blksize</code></em></span></dt><dd>A file system-specific preferred I/O block size
        for this object.  In some file system types, this may vary from
        file to file.</dd><dt><span class="term"><em class="structfield"><code>blocks</code></em></span></dt><dd>Number of blocks allocated for this object.
     </dd></dl></div><p>
    All slots are read-only.</p><p class="simpara">If the system does not support a particular field (e.g.,
    <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> prior to 2000 does not have hard links), <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> (or the
    default, like 1 for the number of hard links for old <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>) is
    returned.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><span class="platform">Win32</span> platform only.</h3><p>Normally, one would expect <code class="code">(POSIX:FILE-STAT
      "foo")</code> and <code class="code">(POSIX:FILE-STAT (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_open.html" target="_top"><code class="function">OPEN</code></a> "foo"))</code> to
     return <span class="quote">“<span class="quote">similar</span>”</span> objects (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_open.html" target="_top"><code class="function">OPEN</code></a>ing a file changes its
     access time though).  This is <span class="strong"><strong>not</strong></span> the case on <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>, where
     <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/stat.html"><code class="function">stat</code></a> works but <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fstat.html"><code class="function">fstat</code></a> does <span class="strong"><strong>not</strong></span>.
     Specifically, <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fstat.html"><code class="function">fstat</code></a> requires an <span class="type">int</span> argument of an unknown
     nature, and it is not clear how do deduce it from the <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> file handle.
     Therefore, instead of always failing on open <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_file-stream.html" target="_top"><code class="classname">FILE-STREAM</code></a> arguments,
     this function calls
     <a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=GetFileInformationByHandle"><code class="function">GetFileInformationByHandle</code></a> and
     fills the <span class="type">FILE-STAT</span> return value based on that.
 </p></div></dd><dt><a id="set-file-stat"></a><span class="term"><code class="code">(POSIX:SET-FILE-STAT
    <em class="replaceable"><code>pathname</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :ATIME :MTIME :MODE :UID :GID)</code></span></dt><dd>Set some file attributes using
    <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/chmod.html"><code class="function">chmod</code></a>,
    <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/chown.html"><code class="function">chown</code></a>,
    and <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/utime.html"><code class="function">utime</code></a>.
 </dd><dt><a id="stat-vfs"></a><span class="term"><code class="code">(POSIX:STAT-VFS <em class="replaceable"><code>pathname</code></em>)</code></span></dt><dd><p>Return a <span class="type">STAT-VFS</span> structure.
   <em class="replaceable"><code>pathname</code></em> can be a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>, a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_pathname.html" target="_top"><code class="classname">PATHNAME</code></a>, a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> or a
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_number.html" target="_top"><code class="classname">NUMBER</code></a> (on a <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> system, meaning <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a>).
   The first slot of the structure returned is the string
   or the number on which <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/statvfs.html"><code class="function">statvfs</code></a> or
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fstatvfs.html"><code class="function">fstatvfs</code></a> was called.
   The other slots are members of the <span class="type">struct statvfs</span>:
   </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="structfield"><code>bsize</code></em></span></dt><dd>File system block size.
    </dd><dt><span class="term"><em class="structfield"><code>frsize</code></em></span></dt><dd>Fundamental file system block size.
    </dd><dt><span class="term"><em class="structfield"><code>blocks</code></em></span></dt><dd>Total number of blocks on file system in units of
       <em class="structfield"><code>frsize</code></em>.</dd><dt><span class="term"><em class="structfield"><code>bfree</code></em></span></dt><dd>Total number of free blocks.
    </dd><dt><span class="term"><em class="structfield"><code>bavail</code></em></span></dt><dd>Number of free blocks available to
       non-privileged processes.</dd><dt><span class="term"><em class="structfield"><code>files</code></em></span></dt><dd>Total number of file serial numbers.
    </dd><dt><span class="term"><em class="structfield"><code>ffree</code></em></span></dt><dd>Total number of free file serial numbers.
    </dd><dt><span class="term"><em class="structfield"><code>favail</code></em></span></dt><dd>Number of file serial numbers available to
       non-privileged processes.</dd><dt><span class="term"><em class="structfield"><code>fsid</code></em></span></dt><dd>File system ID.</dd><dt><span class="term"><em class="structfield"><code>flag</code></em></span></dt><dd>List of platform-dependent values, such as <code class="constant">:READ-ONLY</code>.
    </dd><dt><span class="term"><em class="structfield"><code>namemax</code></em></span></dt><dd>Maximum filename length.
   </dd><dt><span class="term"><em class="structfield"><code>vol-name</code></em></span></dt><dd>Volume name (<a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> only).
   </dd><dt><span class="term"><em class="structfield"><code>fs-type</code></em></span></dt><dd>File system type (<a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> only).
   </dd></dl></div><p>
   All slots are read-only.
 </p></dd><dt><a id="chroot"></a><span class="term"><code class="code">(POSIX:CHROOT <em class="replaceable"><code>pathname</code></em>)</code></span></dt><dd><p class="simpara">Change the apparent disk root directory for the current
   running process (and its children) using
   <a class="bsd" href="http://www.freebsd.org/cgi/man.cgi?query=chroot"><code class="function">chroot</code></a>.</p><p class="simpara">Unless the process has superuser privileges, the operation will
    probably fail with <code class="constant">EPERM</code>.</p></dd><dt><a id="file-tree-walk"></a><span class="term"><code class="code">(POSIX:FILE-TREE-WALK <em class="replaceable"><code>pathname</code></em>
   <em class="replaceable"><code>function</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> FD-LIMIT CHDIR DEPTH MOUNT PHYS)</code></span></dt><dd><p>For each object under <em class="replaceable"><code>pathname</code></em> calls <em class="replaceable"><code>function</code></em> with 5
   arguments: </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">the pathname of the object</li><li class="listitem">the <span class="type">FILE-STAT</span> instance containing
     information on the object (or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, see below)</li><li class="listitem"><p>a keyword giving additional information.
      Its value is one of the following:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:F</code></span></dt><dd>The object is a file.
      </dd><dt><span class="term"><code class="constant">:D</code></span></dt><dd>The object is a directory.
      </dd><dt><span class="term"><code class="constant">:DP</code></span></dt><dd>The object is a directory and subdirectories have
        been visited. (This condition shall only occur if the
        <code class="constant">:DEPTH</code> argument is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.)
      </dd><dt><span class="term"><code class="constant">:SL</code></span></dt><dd>The object is a symbolic link. (This condition shall
        only occur if the <code class="constant">PHYS</code> argument is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.)
      </dd><dt><span class="term"><code class="constant">:SLN</code></span></dt><dd>The object is a symbolic link that does not name an
        existing file. (This condition shall only occur if the
        <code class="constant">PHYS</code> argument is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.)
      </dd><dt><span class="term"><code class="constant">:DNR</code></span></dt><dd>The object is a directory that cannot be read.
        The fn function shall not be called for any of its descendants.
      </dd><dt><span class="term"><code class="constant">:NS</code></span></dt><dd> The <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/stat.html"><code class="function">stat</code></a> function
       failed on the object because of lack of appropriate permission.
       The <span class="type">FILE-STAT</span> argument is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
       If <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/stat.html"><code class="function">stat</code></a> fails for any other reason,
       and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.</dd></dl></div><p>
     </p></li><li class="listitem">the offset of the object's filename in the pathname
     passed as the first argument to <em class="replaceable"><code>function</code></em>.</li><li class="listitem">the depth relative to the root of the walk,
     where the root level is 0.</li></ol></div><p class="simpara">As soon as <em class="replaceable"><code>function</code></em> returns non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, this function returns that
    value; if <em class="replaceable"><code>function</code></em> always returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, then this function also returns
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> when the file tree is exhausted.</p><p class="simpara">The <code class="constant">:FD-LIMIT</code> argument defaults to 5.</p><p class="simpara">If <code class="constant">:CHDIR</code> argument is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the function
    shall change the current working directory to each directory as it reports
    files in that directory</p><p class="simpara">If <code class="constant">:DEPTH</code> argument is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the function
    shall report all files in a directory before reporting the directory
    itself.</p><p class="simpara">If <code class="constant">:MOUNT</code> argument is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the function
    shall only report files in the same file system as <em class="replaceable"><code>pathname</code></em>.</p><p class="simpara">If <code class="constant">:PHYS</code> argument is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the function
    shall perform a physical walk and shall not follow symbolic links.</p><p class="simpara">Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/nftw.html"><code class="function">nftw</code></a>.</p></dd><dt><a id="file-info"></a><span class="term"><code class="code">(OS:FILE-INFO <em class="replaceable"><code>pathname</code></em>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> all)</code></span></dt><dd><p>Return the <span class="type">FILE-INFO</span> structure.
    <em class="replaceable"><code>pathname</code></em> should be a <a class="link" href="#path-des" title="Pathname Designators">pathname designator</a>. The 7 slots are</p><table border="0" summary="Simple list" class="simplelist"><tr><td><em class="structfield"><code>attributes</code></em></td></tr><tr><td><em class="structfield"><code>ctime</code></em></td></tr><tr><td><em class="structfield"><code>atime</code></em></td></tr><tr><td><em class="structfield"><code>wtime</code></em></td></tr><tr><td><em class="structfield"><code>size</code></em></td></tr><tr><td><em class="structfield"><code>name</code></em></td></tr><tr><td><em class="structfield"><code>name-short</code></em></td></tr></table><p>When <em class="replaceable"><code>pathname</code></em> is wild, returns just the first match,
    unless the second (optional) argument is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, in which case a
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of objects is returned, one for each match.
 </p></dd><dt><a id="stream-lock"></a><span class="term"><code class="code">(POSIX:STREAM-LOCK <em class="replaceable"><code>stream</code></em>
    <em class="replaceable"><code>lock-p</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    (:BLOCK <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>) (:SHARED <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>) (:START 0) (:END <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>))</code></span></dt><dd><p class="simpara">Set or remove a file lock for the (portion of the)
    file associated with <em class="replaceable"><code>stream</code></em>,
    depending on <em class="replaceable"><code>lock-p</code></em>.
    When <em class="replaceable"><code>block</code></em> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the call is non-blocking,
    and when locking fails, it returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
    When <em class="replaceable"><code>shared</code></em> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>,
    then lock can be shared between several callers.
    Several processes can set a <em class="replaceable"><code>shared</code></em>
    (i.e., <span class="emphasis"><em>read</em></span>) lock, but only one can set
    an <em class="replaceable"><code>exclusive</code></em> (i.e., <span class="emphasis"><em>write</em></span>,
    or non-<em class="replaceable"><code>shared</code></em>) lock.
    Uses <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fcntl.html"><code class="function">fcntl</code></a>
    or <a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=LockFileEx"><code class="function">LockFileEx</code></a>.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> and <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> differ on locking 0-length files: on
     <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>, two processes can have exclusive locks on it!</p></div><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> locks are <span class="emphasis"><em>mandatory</em></span>:
     if you lock a file, others will not be able to open it!</p><p><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> locks are usually <span class="emphasis"><em>advisory</em></span>: a process
     is free to ignore it, but on some <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> systems one can mount some
     file system with <span class="emphasis"><em>mandatory</em></span> locks.</p></div></dd><dt><a id="with-stream-lock"></a><span class="term"><code class="code">(POSIX:WITH-STREAM-LOCK
    (<em class="replaceable"><code>stream</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>options</code></em>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> <em class="replaceable"><code>body</code></em>)</code></span></dt><dd>Lock the <em class="replaceable"><code>stream</code></em>, execute the <em class="replaceable"><code>body</code></em>, unlock
    the <em class="replaceable"><code>stream</code></em>.  Pass <em class="replaceable"><code>options</code></em> to <a class="link" href="#stream-lock"><code class="function">POSIX:STREAM-LOCK</code></a>.
 </dd><dt><a id="fcntl"></a><span class="term"><code class="code">(<a class="link" href="#fcntl"><code class="function">POSIX:STREAM-OPTIONS</code></a>
    <em class="replaceable"><code>stream</code></em> <em class="replaceable"><code>command</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>value</code></em>)</code></span></dt><dd><p class="simpara">Call <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fcntl.html"><code class="function">fcntl</code></a>,
    <em class="replaceable"><code>command</code></em> can be <code class="constant">:FD</code> or <code class="constant">:FL</code>.
 </p><p class="simpara">When <em class="replaceable"><code>value</code></em> is missing, the option is queried and
  the value is returned; if <em class="replaceable"><code>value</code></em> is supplied, the option is set and
  no values are returned.</p></dd><dt><a id="file-size"></a><span class="term"><code class="code">(<a class="link" href="#file-size"><code class="function">POSIX:FILE-SIZE</code></a> <em class="replaceable"><code>file</code></em>)</code><br /></span><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="link" href="#file-size"><code class="function">POSIX:FILE-SIZE</code></a> <em class="replaceable"><code>file</code></em>) <em class="replaceable"><code>size</code></em>)</code></span></dt><dd><p class="simpara">Extend <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_file-length.html" target="_top"><code class="function">FILE-LENGTH</code></a> to operate on <a class="link" href="#path-des" title="Pathname Designators">pathname designator</a>s.</p><p class="simpara">Set the <em class="replaceable"><code>size</code></em> of a <em class="replaceable"><code>file</code></em> using
    <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/ftruncate.html"><code class="function">ftruncate</code></a> (if <em class="replaceable"><code>file</code></em> is an open
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_file-stream.html" target="_top"><code class="classname">FILE-STREAM</code></a>) or <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/truncate.html"><code class="function">truncate</code></a> (if
    <em class="replaceable"><code>file</code></em> is a <a class="link" href="#path-des" title="Pathname Designators">pathname designator</a>).</p><p class="simpara">Use <a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=SetFilePointerEx"><code class="function">SetFilePointerEx</code></a>
    and <a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=SetEndOfFile"><code class="function">SetEndOfFile</code></a> on <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>.
 </p></dd><dt><a id="mknod"></a><span class="term"><code class="code">(POSIX:MKNOD <em class="replaceable"><code>pathname</code></em> <em class="replaceable"><code>type</code></em>
    <em class="replaceable"><code>mode</code></em>)</code></span></dt><dd>Create a special file using
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/mknod.html"><code class="function">mknod</code></a>.
   Use <code class="constant">:FIFO</code> to create pipes
   and <code class="constant">:SOCK</code> to create sockets.
 </dd><dt><a id="convert-mode"></a><span class="term"><code class="code">(POSIX:CONVERT-MODE <em class="replaceable"><code>mode</code></em>)</code></span></dt><dd>Convert between numeric, (e.g., <code class="literal">0644</code>)
    and symbolic (e.g., <span class="data"><code class="literal">(:RUSR :WUSR :RGRP
     :ROTH)</code></span>) file modes.</dd><dt><a id="umask"></a><span class="term"><code class="code">(POSIX:UMASK <em class="replaceable"><code>mode</code></em>)</code></span></dt><dd>Change process mask using
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/umask.html"><code class="function">umask</code></a>.
 </dd><dt><a id="copy-file"></a><span class="term"><code class="code">(<a class="link" href="#copy-file"><code class="function">POSIX:COPY-FILE</code></a> <em class="replaceable"><code>source</code></em> <em class="replaceable"><code>destination</code></em>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :METHOD :PRESERVE :IF-EXISTS :IF-DOES-NOT-EXIST)</code></span></dt><dd><p class="simpara">This is an interface to
    <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/symlink.html"><code class="function">symlink</code></a>
    (when <em class="replaceable"><code>method</code></em> is <code class="constant">:SYMLINK</code>),
    <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/link.html"><code class="function">link</code></a>
    (when it is <code class="constant">:HARDLINK</code>),
    and <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/rename.html"><code class="function">rename</code></a>
    (when it is <code class="constant">:RENAME</code>) system calls, as well as,
    you guessed it, a generic file copy utility (when <em class="replaceable"><code>method</code></em> is <code class="constant">:COPY</code>).
   </p><p class="simpara">When <em class="replaceable"><code>method</code></em> is <code class="constant">:HARDLINK-OR-COPY</code>
    and <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/link.html"><code class="function">link</code></a> fails (e.g., because the
    <em class="replaceable"><code>source</code></em> and <em class="replaceable"><code>destination</code></em> are on different devices), fall back to <code class="constant">:COPY</code>.
   </p><p class="simpara">Both <em class="replaceable"><code>source</code></em> and <em class="replaceable"><code>destination</code></em> may be wild, in which
    case <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_translate-pathname.html" target="_top"><code class="function">TRANSLATE-PATHNAME</code></a> is used.</p><p class="simpara">When <em class="replaceable"><code>preserve</code></em> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, try
    to duplicate the time, owner, and permission characteristics of each
    source file in the corresponding destination file,
    similar to <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/cp.html"><span class="command"><strong>cp -p</strong></span></a>.</p><p class="simpara">The meaning and defaults of <code class="constant">:IF-EXISTS</code> and
    <code class="constant">:IF-DOES-NOT-EXIST</code> are the same as in <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_open.html" target="_top"><code class="function">OPEN</code></a>.</p></dd><dt><a id="dup-handle"></a><span class="term"><code class="code">(<a class="link" href="#dup-handle"><code class="function">POSIX:DUPLICATE-HANDLE</code></a>
    <em class="replaceable"><code>fd1</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
    <em class="replaceable"><code>fd2</code></em>)</code></span></dt><dd>This is an interface to the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/dup.html"><code class="function">dup</code></a> system calls on
    <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> systems and to <a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=DuplicateHandle"><code class="function">DuplicateHandle</code></a>
    system call on <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>.</dd><dt><a id="shortcut-info"></a><span class="term"><code class="code">(OS:SHORTCUT-INFO
    <em class="replaceable"><code>pathname</code></em>)</code></span></dt><dd>Return information about a <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> shortcut
    (<code class="filename">#P".lnk"</code>) file contents in a
    <span class="type">SHORTCUT-INFO</span> structure.</dd><dt><a id="make-shortcut"></a><span class="term"><code class="code">(OS:MAKE-SHORTCUT <em class="replaceable"><code>pathname</code></em>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :WORKING-DIRECTORY :ARGUMENTS :SHOW-COMMAND :ICON :DESCRIPTION
    :HOT-KEY :PATH)</code></span></dt><dd>Create (or modify the properties of an existing one)
    a <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> shortcut (<code class="filename">#P".lnk"</code>) file.
 </dd><dt><a id="file-properties"></a><span class="term"><code class="code">(OS:FILE-PROPERTIES
    filename set <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :INITID <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;ALLOW-OTHER-KEYS</code></a>)</code></span></dt><dd><p>Wrapper for the <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>
    <a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=IPropertyStorage"><code class="function">IPropertyStorage</code></a> functionality.
    </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>filename</code></em></span></dt><dd>name of a compound file (where properties are stored)
      or (on NTFS) name of any file (properties are stored in the filesystem).
      For compound files on NTFS, file storage is preferred.
     </dd><dt><span class="term"><em class="replaceable"><code>set</code></em></span></dt><dd>property set, either <code class="constant">:BUILT-IN</code>
        or <code class="constant">:USER-DEFINED</code>
     </dd><dt><span class="term"><code class="constant">:INITID</code>
       <em class="replaceable"><code>init-id</code></em></span></dt><dd>set the <em class="replaceable"><code>init-id</code></em>
     </dd><dt><span class="term"><em class="replaceable"><code>specifier value</code></em></span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>specifier</code></em></span></dt><dd><p>the property specifier: an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>,
            <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_keyword.html" target="_top"><code class="classname">KEYWORD</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> or a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> or a
            <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_keyword.html" target="_top"><code class="classname">KEYWORD</code></a> and a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>.
            </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a></span></dt><dd>a property identifier
             </dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_keyword.html" target="_top"><code class="classname">KEYWORD</code></a></span></dt><dd><p>Predefined <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_keyword.html" target="_top"><code class="classname">KEYWORD</code></a> IDs are
                </p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="constant">:APPNAME</code></td><td><code class="constant">:CREATE-DTM</code></td><td><code class="constant">:LASTPRINTED</code></td><td><code class="constant">:SUBJECT</code></td></tr><tr><td><code class="constant">:AUTHOR</code></td><td><code class="constant">:DOC-SECURITY</code></td><td><code class="constant">:LASTSAVE-DTM</code></td><td><code class="constant">:TEMPLATE</code></td></tr><tr><td><code class="constant">:CHARCOUNT</code></td><td><code class="constant">:EDITTIME</code></td><td><code class="constant">:LOCALE</code></td><td><code class="constant">:THUMBNAIL</code></td></tr><tr><td><code class="constant">:CODEPAGE</code></td><td><code class="constant">:KEYWORDS</code></td><td><code class="constant">:PAGECOUNT</code></td><td><code class="constant">:TITLE</code></td></tr><tr><td><code class="constant">:COMMENTS</code></td><td><code class="constant">:LASTAUTHOR</code></td><td><code class="constant">:REVNUMBER</code></td><td><code class="constant">:WORDCOUNT</code></td></tr></table></dd><dt><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a></span></dt><dd>string property specifier.
                If no match is found, the first ID &gt;= init-id
                (which defaults to 2) is associated with the
                string and its value is replaced with new value.
             </dd><dt><span class="term">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>|<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_keyword.html" target="_top"><code class="classname">KEYWORD</code></a>
               <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>)</span></dt><dd>the first element is used as
                a specifier, the string is associated with this ID.
            </dd></dl></div><p>
           </p></dd><dt><span class="term"><em class="replaceable"><code>value</code></em></span></dt><dd><p>the new value of the property, a suitable Lisp
            object, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> or a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_keyword.html" target="_top"><code class="classname">KEYWORD</code></a> and the value
            itself.  If <em class="replaceable"><code>value</code></em> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, no assignment is done.
            <code class="constant">:EMPTY</code> and <code class="constant">:NULL</code>
            correspond to the <span class="type">VT_EMPTY</span>
            and <span class="type">VT_NULL</span> data types.
            <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_keyword.html" target="_top"><code class="classname">KEYWORD</code></a> in the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> specifies the desired type of
            the property being set.
            Supported types are</p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="constant">:BOOL</code></td><td><code class="constant">:I1</code></td><td><code class="constant">:LPWSTR</code></td><td><code class="constant">:UI4</code></td></tr><tr><td><code class="constant">:BSTR</code></td><td><code class="constant">:I2</code></td><td><code class="constant">:R4</code></td><td><code class="constant">:UI8</code></td></tr><tr><td><code class="constant">:DATE</code></td><td><code class="constant">:I4</code></td><td><code class="constant">:R8</code></td><td><code class="constant">:UINT</code></td></tr><tr><td><code class="constant">:ERROR</code></td><td><code class="constant">:I8</code></td><td><code class="constant">:UI1</code></td><td> </td></tr><tr><td><code class="constant">:FILETIME</code></td><td><code class="constant">:LPSTR</code></td><td><code class="constant">:UI2</code></td><td> </td></tr></table><p>
            <span class="type">FILETIME</span>s are converted to/from the universal
            time format, while <span class="type">DATE</span>s are not.
       </p></dd></dl></div><p>
    </p></dd></dl></div><p>
    Returns the property contents before assignment as multiple values.
 </p></dd><dt><a id="file-owner"></a><span class="term"><code class="code">(OS:FILE-OWNER
    <em class="replaceable"><code>filename</code></em>)</code></span></dt><dd><p class="simpara">Return the owner of the file.</p><p class="simpara"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platforms only.</span></span></p></dd><dt><a id="mkstemp"></a><span class="term"><code class="code">(POSIX:MKSTEMP <em class="replaceable"><code>filename</code></em>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:DIRECTION</code> <a class="link" href="#eltype"><code class="constant">:ELEMENT-TYPE</code></a> <a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a> <a class="link" href="#buffered"><code class="constant">:BUFFERED</code></a>)</code></span></dt><dd><p class="simpara">Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/mkstemp.html"><code class="function">mkstemp</code></a>;
    returns a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_file-stream.html" target="_top"><code class="classname">FILE-STREAM</code></a>.</p><p class="simpara"><code class="constant">:DIRECTION</code> should allow output.</p></dd><dt><a id="mkdtemp"></a><span class="term"><code class="code">(POSIX:MKDTEMP
    <em class="replaceable"><code>filename</code></em>)</code></span></dt><dd>Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/mkdtemp.html"><code class="function">mkdtemp</code></a>;
    creates a new empty temporary directory and returns its namestring.
 </dd><dt><a id="sync"></a><span class="term"><code class="code">(POSIX:SYNC <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
    <em class="replaceable"><code>stream</code></em>)</code></span></dt><dd>Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fsync.html"><code class="function">fsync</code></a>
    (<a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=FlushFileBuffers"><code class="function">FlushFileBuffers</code></a> on <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>)
    on the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a> associated with <em class="replaceable"><code>stream</code></em>,
    or <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/sync.html"><code class="function">sync</code></a>
    when <em class="replaceable"><code>stream</code></em> is not supplied</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="user-group"></a>33.2.3. Users and Groups</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><a id="user-info"></a><span class="term"><code class="code">(POSIX:USER-INFO
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>user</code></em>)</code></span></dt><dd><p class="simpara">Return the <span class="type">USER-INFO</span> structure (name,
   encoded password, UID, GID, full name, home directory, shell).
   <em class="replaceable"><code>user</code></em> should be a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>
   (<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getpwnam.html"><code class="function">getpwnam</code></a> is used) or an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>
   (<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getpwuid.html"><code class="function">getpwuid</code></a> is used).
   When <em class="replaceable"><code>user</code></em> is missing or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, return all
   users (using <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getpwent.html"><code class="function">getpwent</code></a>).
   When <em class="replaceable"><code>user</code></em> is <code class="constant">:DEFAULT</code>, return the information about the current user
   (using <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getlogin.html"><code class="function">getlogin</code></a>).</p><p class="simpara"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> platform only.</span></span></p></dd><dt><a id="group-info"></a><span class="term"><code class="code">(POSIX:GROUP-INFO
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>group</code></em>)</code></span></dt><dd><p class="simpara">Return the <span class="type">GROUP-INFO</span> structure (name,
   GID, member <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>). <em class="replaceable"><code>group</code></em> should be a
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> (<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getgrnam.html"><code class="function">getgrnam</code></a> is used) or an
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> (<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getgrgid.html"><code class="function">getgrgid</code></a> is used).
   When <em class="replaceable"><code>group</code></em> is missing or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, return all
   groups (using <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getgrent.html"><code class="function">getgrent</code></a>).</p><p class="simpara"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> platform only.</span></span></p></dd><dt><a id="user-shells"></a><span class="term"><code class="code">(POSIX:USER-SHELLS)</code></span></dt><dd>Call <a class="bsd" href="http://www.freebsd.org/cgi/man.cgi?query=getusershell"><code class="function">getusershell</code></a>.
</dd><dt><a id="get-user-sid"></a><span class="term"><code class="code">(OS:GET-USER-SID
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>user</code></em>)</code></span></dt><dd>Call <a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=LookupAccountName"><code class="function">LookupAccountName</code></a>
  on <em class="replaceable"><code>user</code></em> or, if that is not supplied, call
  <a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=OpenProcessToken"><code class="function">OpenProcessToken</code></a>,
  <a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=GetTokenInformation"><code class="function">GetTokenInformation</code></a>, and then
  <a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=ConvertSidToStringSid"><code class="function">ConvertSidToStringSid</code></a> on
  <em class="structfield"><code>User.Sid</code></em>.</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="sysinfo"></a>33.2.4. System Information</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><a id="uname"></a><span class="term"><code class="code">(POSIX:UNAME)</code></span></dt><dd>Return a structure describing the OS, derived from
    <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/uname.html"><code class="function">uname</code></a>.</dd><dt><a id="sysconf"></a><span class="term"><code class="code">(POSIX:SYSCONF <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>what</code></em>)</code><br /></span><span class="term"><code class="code">(POSIX:CONFSTR <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>what</code></em>)</code></span></dt><dd>Return the specified configuration parameter or a
    <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#property_list">property list</a> of all available parameters (when <em class="replaceable"><code>what</code></em> is missing or
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>), by calling <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/sysconf.html"><code class="function">sysconf</code></a>
    and <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/confstr.html"><code class="function">confstr</code></a> respectively.
 </dd><dt><a id="pathconf"></a><span class="term"><code class="code">(POSIX:PATHCONF <em class="replaceable"><code>pathname</code></em>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>what</code></em>)</code></span></dt><dd>Return the specified configuration parameter or a
    <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#property_list">property list</a> of all available parameters (when <em class="replaceable"><code>what</code></em> is missing or
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>), by calling <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fpathconf.html"><code class="function">fpathconf</code></a> on
    open file streams and <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/pathconf.html"><code class="function">pathconf</code></a> on
    all other <a class="link" href="#path-des" title="Pathname Designators">pathname designator</a>s.</dd><dt><a id="rlimit"></a><span class="term"><code class="code">(<a class="link" href="#rlimit"><code class="function">POSIX:RLIMIT</code></a>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>what</code></em>)</code></span></dt><dd>Return the current and the maximal limits as two
    values when <em class="replaceable"><code>what</code></em> is specified or the <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#property_list">property list</a> of all available
    limits (as an <span class="type">RLIMIT</span> structure) when <em class="replaceable"><code>what</code></em> is
    missing or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, by calling <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getrlimit.html"><code class="function">getrlimit</code></a>.
 </dd><dt><a id="set-rlimit"></a><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="link" href="#rlimit"><code class="function">POSIX:RLIMIT</code></a> <em class="replaceable"><code>what</code></em>)
    (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_values.html" target="_top"><code class="function">VALUES</code></a> <em class="replaceable"><code>cur</code></em>
    <em class="replaceable"><code>max</code></em>))</code><br /></span><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="link" href="#rlimit"><code class="function">POSIX:RLIMIT</code></a> <em class="replaceable"><code>what</code></em>)
    <em class="replaceable"><code>rlimit</code></em>)</code><br /></span><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (<a class="link" href="#rlimit"><code class="function">POSIX:RLIMIT</code></a>)
    <em class="replaceable"><code>rlimit-plist</code></em>)</code></span></dt><dd><p>Set the limits using
    <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/setrlimit.html"><code class="function">setrlimit</code></a>.</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">In the first form, <em class="replaceable"><code>cur</code></em>
       and <em class="replaceable"><code>max</code></em> are numbers
       (or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> for <code class="constant">RLIM_INFINITY</code>).</li><li class="listitem">In the second form, <em class="replaceable"><code>rlimit</code></em>
       is an <span class="type">RLIMIT</span> structure.</li><li class="listitem">In the third form,
       <em class="replaceable"><code>rlimit-plist</code></em> is a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#property_list">property list</a>, as returned by
       <code class="code">(<a class="link" href="#rlimit"><code class="function">POSIX:RLIMIT</code></a>)</code>.</li></ol></div></dd><dt><a id="usage"></a><span class="term"><code class="code">(<a class="link" href="#usage"><code class="function">POSIX:USAGE</code></a>
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>what</code></em>)</code></span></dt><dd>Return the <span class="type">USAGE</span> structure describing the
   resource usage of the thread, process, or its children, using
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getrusage.html"><code class="function">getrusage</code></a>. WHen <em class="replaceable"><code>what</code></em> is missing
   or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, return all available data as a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#property_list">property list</a>.
 </dd><dt><a id="bogomips"></a><span class="term"><code class="code">(POSIX:BOGOMIPS)</code></span></dt><dd>Compute the
    <a class="ulink" href="http://en.wikipedia.org/wiki/BogoMips" target="_top">BogoMips</a>
    rating.</dd><dt><a id="loadavg"></a><span class="term"><code class="code">(POSIX:LOADAVG <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
    percentp)</code></span></dt><dd>Return 1, 5, and 15 minute system load averages,
    retrieved by <a class="bsd" href="http://www.freebsd.org/cgi/man.cgi?query=getloadavg"><code class="function">getloadavg</code></a>.
    If the argument is specified and non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the values are returned
    as integer percentiles.</dd><dt><span class="term"><code class="code">(OS:SYSTEM-INFO)</code></span></dt><dd>Return <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> system information in a
    <span class="type">SYSTEM-INFO</span> structure.</dd><dt><span class="term"><code class="code">(OS:VERSION)</code></span></dt><dd>Return <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> version information in a
    <span class="type">VERSION</span> structure.</dd><dt><span class="term"><code class="code">(OS:MEMORY-STATUS)</code></span></dt><dd>Return <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> memory status information in a
    <span class="type">MEMORY-STATUS</span> structure.</dd><dt><a id="phys-mem"></a><span class="term"><code class="code">(OS:PHYSICAL-MEMORY)</code></span></dt><dd><p class="simpara">Return 2 values: total and available physical memory.
   </p><p class="simpara"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platforms only.</span></span></p></dd><dt><a id="hostid"></a><span class="term"><code class="code">(OS:HOSTID)</code><br /></span><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (OS:HOSTID) <em class="replaceable"><code>value</code></em>)</code></span></dt><dd><p class="simpara">Call <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/gethostid.html"><code class="function">gethostid</code></a> and
    return a (hopefully) universally unique <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> identifier of
    this machine.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>On <a class="ulink" href="https://www.kernel.org/" target="_top"><span class="platform">Linux</span></a> this number appears to be the IPv4 32-bit
     address with the first 2 bytes and the last 2 bytes swapped:
</p><pre class="programlisting">(<a class="link" href="#rawsock-convert-address"><code class="function">RAWSOCK:CONVERT-ADDRESS</code></a> :inet (os:hostid))
⇒ <code class="computeroutput">"7.3.192.168"</code>
(first (posix:hostent-addr-list (<a class="link" href="#resolve-host"><code class="function">POSIX:RESOLVE-HOST-IPADDR</code></a> :default)))
⇒ <code class="computeroutput">"192.168.7.3"</code></pre><p>This, of
course, means that <span class="quote">“<span class="quote">universally unique</span>”</span> it is <span class="strong"><strong>not</strong></span>.
   </p></div><p class="simpara">Superuser can also set host identifier
    using <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> which calls <a class="bsd" href="http://www.freebsd.org/cgi/man.cgi?query=sethostid"><code class="function">sethostid</code></a>.
   </p><p class="simpara"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>, <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platforms only.</span></span></p></dd><dt><a id="domainname"></a><span class="term"><code class="code">(OS:DOMAINNAME)</code><br /></span><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (OS:DOMAINNAME) <em class="replaceable"><code>domain</code></em>)</code></span></dt><dd>Call <a class="bsd" href="http://www.freebsd.org/cgi/man.cgi?query=getdomainname"><code class="function">getdomainname</code></a>
    and <a class="bsd" href="http://www.freebsd.org/cgi/man.cgi?query=setdomainname"><code class="function">setdomainname</code></a>.</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="posix-math"></a>33.2.5. Mathematical functions</h3></div></div></div><p>We implement access to </p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/erf.html"><code class="function">erf</code></a> <em class="replaceable"><code>real</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/erfc.html"><code class="function">erfc</code></a> <em class="replaceable"><code>real</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/j0.html"><code class="function">j0</code></a> <em class="replaceable"><code>real</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/j1.html"><code class="function">j1</code></a> <em class="replaceable"><code>real</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/jn.html"><code class="function">jn</code></a> <em class="replaceable"><code>integer</code></em>
    <em class="replaceable"><code>real</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/y0.html"><code class="function">y0</code></a> <em class="replaceable"><code>real</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/y1.html"><code class="function">y1</code></a> <em class="replaceable"><code>real</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/yn.html"><code class="function">yn</code></a> <em class="replaceable"><code>integer</code></em>
    <em class="replaceable"><code>real</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/tgamma.html"><code class="function">tgamma</code></a>
    <em class="replaceable"><code>real</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/lgamma.html"><code class="function">lgamma</code></a>
    <em class="replaceable"><code>real</code></em>)</code></td></tr></table><p>
which compute the error functions, Bessel functions and Gamma.</p><p>These functions are required by the <a class="ulink" href="http://www.opengroup.org/austin/papers/posix_faq.html" target="_top"><span class="platform">POSIX</span></a> standard and should
 be declared in <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/math.h.html">&lt;<code class="filename">math.h</code>&gt;</a>.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>Please note that these functions do <span class="strong"><strong>not</strong></span> provide
  lisp-style error handling and precision, and do all the computations
  at the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">DOUBLE-FLOAT</code></a> level.</p></div><p>Function <code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/ffs.html"><code class="function">ffs</code></a> <em class="replaceable"><code>n</code></em>)</code>
 finds the first bit set. It is implemented in pure Lisp and supports
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_bignum.html" target="_top"><code class="classname">BIGNUM</code></a>s.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="encryption"></a>33.2.6. Encryption</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><a id="crypt"></a><span class="term"><code class="code">(POSIX:CRYPT <em class="replaceable"><code>key</code></em>
    <em class="replaceable"><code>salt</code></em>)</code></span></dt><dd>Call <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/crypt.html"><code class="function">crypt</code></a>,
    arguments are <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>s.</dd><dt><a id="encrypt"></a><span class="term"><code class="code">(POSIX:ENCRYPT <em class="replaceable"><code>block</code></em>
    <em class="replaceable"><code>decrypt-p</code></em>)</code><br /></span><span class="term"><code class="code">(POSIX:SETKEY <em class="replaceable"><code>key</code></em>)</code></span></dt><dd>Call <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/encrypt.html"><code class="function">encrypt</code></a>
    and <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/setkey.html"><code class="function">setkey</code></a>, respectively.
    <em class="replaceable"><code>block</code></em> and <em class="replaceable"><code>key</code></em> are of type
    <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_vector.html" target="_top"><code class="function">VECTOR</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8) 8)</code></span>.
    <em class="replaceable"><code>decrypt-p</code></em> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_boolean.html" target="_top"><code class="classname">BOOLEAN</code></a>.
 </dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="sys-log"></a>33.2.7. Syslog</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><a id="openlog"></a><span class="term"><code class="code">(POSIX:OPENLOG ident <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    :PID :CONS :NDELAY :ODELAY :NOWAIT :FACILITY)</code></span></dt><dd>Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/openlog.html"><code class="function">openlog</code></a>
 </dd><dt><a id="setlogmask"></a><span class="term"><code class="code">(POSIX:SETLOGMASK
    maskpri)</code></span></dt><dd>Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/setlogmask.html"><code class="function">setlogmask</code></a>.
 </dd><dt><a id="syslog"></a><span class="term"><code class="code">(POSIX:SYSLOG severity facility
    <em class="replaceable"><code>format-string</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>arguments</code></em>)</code></span></dt><dd><p class="simpara">Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/syslog.html"><code class="function">syslog</code></a> on
    <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_apply.html" target="_top"><code class="function">APPLY</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> <em class="replaceable"><code>format-string</code></em> <em class="replaceable"><code>arguments</code></em>)</code>.</p><p class="simpara">No <span class="data"><code class="literal">%</code></span> conversion is performed,
    you must do all formatting in Lisp.</p></dd><dt><a id="closelog"></a><span class="term"><code class="code">(POSIX:CLOSELOG)</code></span></dt><dd>Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/closelog.html"><code class="function">closelog</code></a>.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="processes"></a>33.2.8. Processes</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><a id="process-id"></a><span class="term"><code class="code">(OS:PROCESS-ID)</code></span></dt><dd>Return the process ID
    (on <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getpid.html"><code class="function">getpid</code></a>,
    on <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> calls <a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=GetCurrentProcessId"><code class="function">GetCurrentProcessId</code></a>)
 </dd><dt><a id="priority"></a><span class="term"><code class="code">(OS:PRIORITY <em class="replaceable"><code>pid</code></em>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>what</code></em>)</code><br /></span><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (OS:PRIORITY <em class="replaceable"><code>pid</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>what</code></em>)
    priority)</code></span></dt><dd><p>Return or set the process priority, platform-dependent
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> or platform-independent <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>, one of
    </p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="constant">:REALTIME</code></td><td><code class="constant">:NORMAL</code></td><td><code class="constant">:IDLE</code></td></tr><tr><td><code class="constant">:HIGH</code></td><td><code class="constant">:BELOW-NORMAL</code></td><td> </td></tr><tr><td><code class="constant">:ABOVE-NORMAL</code></td><td><code class="constant">:LOW</code></td><td> </td></tr></table><p>
    On <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getpriority.html"><code class="function">getpriority</code></a>
    and <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/setpriority.html"><code class="function">setpriority</code></a>, on
    <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> calls <a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=GetPriorityClass"><code class="function">GetPriorityClass</code></a> and
    <a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=SetPriorityClass"><code class="function">SetPriorityClass</code></a>.</p></dd><dt><a id="kill"></a><span class="term"><code class="code">(POSIX:KILL <em class="replaceable"><code>pid</code></em> <em class="replaceable"><code>signal</code></em>)</code></span></dt><dd>Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/kill.html"><code class="function">kill</code></a>.
 </dd><dt><a id="getppid"></a><span class="term"><code class="code">(POSIX:GETPPID)</code></span></dt><dd>Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getppid.html"><code class="function">getppid</code></a>.
 </dd><dt><a id="getpgrp"></a><span class="term"><code class="code">(POSIX:GETPGRP)</code></span></dt><dd>Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getpgrp.html"><code class="function">getpgrp</code></a>.
 </dd><dt><a id="setpgrp"></a><span class="term"><code class="code">(POSIX:SETPGRP)</code></span></dt><dd>Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/setpgrp.html"><code class="function">setpgrp</code></a>;
    on non-<a class="ulink" href="http://www.opengroup.org/austin/papers/posix_faq.html" target="_top"><span class="platform">POSIX</span></a> systems where it requires 2 arguments (legacy
    BSD-style), it is called as <code class="code">setpgrp(0,0)</code>.
 </dd><dt><a id="getsid"></a><span class="term"><code class="code">(POSIX:GETSID <em class="replaceable"><code>pid</code></em>)</code></span></dt><dd>Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getsid.html"><code class="function">getsid</code></a>.
 </dd><dt><a id="setsid"></a><span class="term"><code class="code">(POSIX:SETSID)</code></span></dt><dd>Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/setsid.html"><code class="function">setsid</code></a>.
 </dd><dt><a id="getpgid"></a><span class="term"><code class="code">(POSIX:PGID <em class="replaceable"><code>pid</code></em>)</code><br /></span><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (POSIX:PGID <em class="replaceable"><code>pid</code></em>)
    <em class="replaceable"><code>pgid</code></em>)</code></span></dt><dd>Call <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getpgid.html"><code class="function">getpgid</code></a> and
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/setpgid.html"><code class="function">setpgid</code></a>.</dd><dt><a id="setreuid"></a><span class="term"><code class="code">(POSIX:SETREUID
    ruid euid)</code></span></dt><dd>Call <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/setreuid.html"><code class="function">setreuid</code></a>.
 </dd><dt><a id="setregid"></a><span class="term"><code class="code">(POSIX:SETREGID
    rgid egid)</code></span></dt><dd>Call <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/setregid.html"><code class="function">setregid</code></a>.
 </dd><dt><a id="getuid"></a><span class="term"><code class="code">(POSIX:UID)</code><br /></span><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (POSIX:UID) <em class="replaceable"><code>uid</code></em>)</code></span></dt><dd>Call <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getuid.html"><code class="function">getuid</code></a> and
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/setuid.html"><code class="function">setuid</code></a>.</dd><dt><a id="getgid"></a><span class="term"><code class="code">(POSIX:GID)</code><br /></span><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (POSIX:GID) <em class="replaceable"><code>gid</code></em>)</code></span></dt><dd>Call <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getgid.html"><code class="function">getgid</code></a> and
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/setgid.html"><code class="function">setgid</code></a>.</dd><dt><a id="geteuid"></a><span class="term"><code class="code">(POSIX:EUID)</code><br /></span><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (POSIX:EUID) <em class="replaceable"><code>uid</code></em>)</code></span></dt><dd>Call <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/geteuid.html"><code class="function">geteuid</code></a> and
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/seteuid.html"><code class="function">seteuid</code></a>.</dd><dt><a id="getegid"></a><span class="term"><code class="code">(POSIX:EGID)</code><br /></span><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (POSIX:EGID) <em class="replaceable"><code>gid</code></em>)</code></span></dt><dd>Call <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getegid.html"><code class="function">getegid</code></a> and
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/setegid.html"><code class="function">setegid</code></a>.</dd><dt><a id="getgroups"></a><span class="term"><code class="code">(POSIX:GROUPS)</code><br /></span><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (POSIX:GROUPS) <em class="replaceable"><code>list</code></em>)</code></span></dt><dd>Call <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getgroups.html"><code class="function">getgroups</code></a> and
   <a class="bsd" href="http://www.freebsd.org/cgi/man.cgi?query=setgroups"><code class="function">setgroups</code></a>.
 </dd><dt><a id="wait"></a><span class="term"><code class="code">(<a class="link" href="#wait"><code class="function">POSIX:WAIT</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :PID :USAGE
    :NOHANG :UNTRACED :STOPPED :EXITED :CONTINUED :NOWAIT)</code></span></dt><dd><p class="simpara">Wait for termination of the child process
    <code class="constant">:PID</code> (or any child process if not specified).</p><p class="simpara">If <code class="constant">:NOHANG</code> is specifed, return <code class="literal">0</code>
    as the only value immediately if no child process has terminated.</p><p class="simpara">Otherwise, the first return value is the <em class="replaceable"><code>pid</code></em> of the
    terminated child process.</p><p>The second and third return values depend on the way the
    process terminated:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term">2nd value = <code class="constant">:EXITED</code><br /></span><span class="term">3rd value = <em class="replaceable"><code>exit status</code></em></span></dt><dd>if the child terminated normally, e.g., by
        calling <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/exit.html"><code class="function">exit</code></a>.
     </dd><dt><span class="term">2nd value = <code class="constant">:SIGNALED</code><br /></span><span class="term">3rd value = <em class="replaceable"><code>signal</code></em></span></dt><dd>if the child process was terminated by a <em class="replaceable"><code>signal</code></em>.
     </dd><dt><span class="term">2nd value = <code class="constant">:STOPPED</code><br /></span><span class="term">3rd value = <em class="replaceable"><code>signal</code></em></span></dt><dd>if the child process was stopped by delivery of
        a <em class="replaceable"><code>signal</code></em>.</dd><dt><span class="term">2nd value = <code class="constant">:CONTINUED</code><br /></span><span class="term">3rd value = <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></span></dt><dd>if the child process has continued from a job
        control stop.</dd><dt><span class="term">2nd value = <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a><br /></span><span class="term">3rd value = <em class="replaceable"><code>number</code></em></span></dt><dd>if <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> could not figure out what has happened.
        Please read your local <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/waitpid.html"><code class="function">waitpid</code></a>
        manual and send us a patch.</dd></dl></div><p class="simpara">The fourth value is only returned if <code class="constant">:USAGE</code>
    is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and in that case it is a structure describing resource
    usage by the terminated process, similar to what <a class="link" href="#usage"><code class="function">POSIX:USAGE</code></a> returns.</p><p class="simpara">To avoid race conditions, it is important to start your
    subprocesses <span class="strong"><strong>and</strong></span> <a class="link" href="#wait"><code class="function">POSIX:WAIT</code></a> for them inside the <em class="replaceable"><code>body</code></em> of
    a <a class="link" href="#with-subprocesses"><code class="function">POSIX:WITH-SUBPROCESSES</code></a> form.</p><p class="simpara">Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/waitpid.html"><code class="function">waitpid</code></a> and
    (when the <code class="constant">:USAGE</code> argument is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>)
    <a class="bsd" href="http://www.freebsd.org/cgi/man.cgi?query=wait4"><code class="function">wait4</code></a>.</p></dd><dt><a id="with-subprocesses"></a><span class="term"><code class="code">(<a class="link" href="#with-subprocesses"><code class="function">POSIX:WITH-SUBPROCESSES</code></a>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a>)</code></span></dt><dd>Evaluate <em class="replaceable"><code>body</code></em> while receiving signals from
   subprocesses; your <a class="link" href="#run-prog"><code class="function">EXT:RUN-PROGRAM</code></a> and related <a class="link" href="#wait"><code class="function">POSIX:WAIT</code></a> calls should be
   inside it.</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="accounting"></a>33.2.9. Accounting</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><a id="endutxent"></a><span class="term"><code class="code">(POSIX:ENDUTXENT)</code></span></dt><dd>Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/endutxent.html"><code class="function">endutxent</code></a>.
 </dd><dt><a id="getutxent"></a><span class="term"><code class="code">(POSIX:GETUTXENT
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> utmpx)</code></span></dt><dd>Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getutxent.html"><code class="function">getutxent</code></a>,
    returns a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_structure-object.html" target="_top"><code class="classname">STRUCTURE-OBJECT</code></a> of type <span class="type">POSIX:UTMPX</span>,
    which can be passed to subsequent calls to this function and re-used.
 </dd><dt><a id="getutxid"></a><span class="term"><code class="code">(POSIX:GETUTXID id)</code></span></dt><dd>Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getutxid.html"><code class="function">getutxid</code></a>,
    the argument is filled and returned.</dd><dt><a id="getutxline"></a><span class="term"><code class="code">(POSIX:GETUTXLINE line)</code></span></dt><dd>Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getutxline.html"><code class="function">getutxline</code></a>,
    the argument is filled and returned.</dd><dt><a id="pututxline"></a><span class="term"><code class="code">(POSIX:PUTUTXLINE
    utmpx)</code></span></dt><dd>Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/pututxline.html"><code class="function">pututxline</code></a>,
    the argument is filled and returned.</dd><dt><a id="setutxent"></a><span class="term"><code class="code">(POSIX:SETUTXENT)</code></span></dt><dd>Calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/setutxent.html"><code class="function">setutxent</code></a>.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="posix-time"></a>33.2.10. Time and Data Conversion</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><a id="strtime"></a><span class="term"><code class="code">(OS:STRING-TIME
  <em class="replaceable"><code>format-string</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>object</code></em> timezone)</code></span></dt><dd><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">When <em class="replaceable"><code>object</code></em> is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>,
   it is parsed into a universal time according to <em class="replaceable"><code>format-string</code></em> by
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/strptime.html"><code class="function">strptime</code></a>.</li><li class="listitem">When it is an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>, it is formatted according
    to <em class="replaceable"><code>format-string</code></em> by <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/strftime.html"><code class="function">strftime</code></a>.
    <em class="replaceable"><code>object</code></em> defaults to <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_get-unive_decoded-time.html" target="_top"><code class="function">GET-UNIVERSAL-TIME</code></a>)</code>.
</li></ul></div></dd><dt><a id="getdate"></a><span class="term"><code class="code">(OS:GETDATE <em class="replaceable"><code>string</code></em>
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> timezone)</code></span></dt><dd><p class="simpara">Parse the <em class="replaceable"><code>string</code></em> into a universal time using
  <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getdate.html"><code class="function">getdate</code></a>.</p><p class="simpara">If the the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html">environment variable</a> <code class="envar">DATEMSK</code> is not set when
   <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> is invoked, <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> sets it to point to the file
   <code class="filename">modules/syscalls/datemsk</code>, installed as
   <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_merge-pathnames.html" target="_top"><code class="function">MERGE-PATHNAMES</code></a> "syscalls/datemsk" <a href="clisp.html#opt-libdir" class="olink"><code class="varname">CUSTOM:*LIB-DIRECTORY*</code></a>)</code>.
</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="strverscmp"></a>33.2.11. String comparision</h3></div></div></div><p>Functions </p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="code">(OS:VERSION&lt; <em class="replaceable"><code>x<sub>1</sub></code></em> <em class="replaceable"><code>x<sub>2</sub></code></em>)</code></td></tr><tr><td><code class="code">(OS:VERSION&lt;= <em class="replaceable"><code>x<sub>1</sub></code></em> <em class="replaceable"><code>x<sub>2</sub></code></em>)</code></td></tr><tr><td><code class="code">(OS:VERSION&gt; <em class="replaceable"><code>x<sub>1</sub></code></em> <em class="replaceable"><code>x<sub>2</sub></code></em>)</code></td></tr><tr><td><code class="code">(OS:VERSION&gt;= <em class="replaceable"><code>x<sub>1</sub></code></em> <em class="replaceable"><code>x<sub>2</sub></code></em>)</code></td></tr></table><p>
 compare two <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>s as version numbers (e.g.,
 <span class="data"><code class="literal">"foo10"</code></span> is <span class="emphasis"><em>greater</em></span> than
 <span class="data"><code class="literal">"foo9"</code></span>) using
 <a class="gnu" href="http://www.kernel.org/doc/man-pages/online/pages/man3/strverscmp.3.html"><code class="function">strverscmp</code></a> and return a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_boolean.html" target="_top"><code class="classname">BOOLEAN</code></a>.</p><p>Function <code class="function">OS:VERSION-COMPARE</code> does the same but
returns either <span class="data"><code class="literal">&lt;</code></span>,
<span class="data"><code class="literal">&gt;</code></span> or <span class="data"><code class="literal">=</code></span>.
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="wildcard"></a>33.2.12. Wildcard Matching</h3></div></div></div><p>Wildcards describe sets of file names; see <span class="quote">“<span class="quote"><a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_13">Pathname Matching</a>
Notation</span>”</span> for the syntax description.</p><p><a id="fnmatch-f"></a><strong><code class="code">(POSIX:FNMATCH <em class="replaceable"><code>pattern</code></em> <em class="replaceable"><code>string</code></em>
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :PATHNAME :PERIOD :NOESCAPE (:CASE-SENSITIVE <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>))</code>. </strong>This function returns a non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> value if the <em class="replaceable"><code>string</code></em> matches
 the <em class="replaceable"><code>pattern</code></em> by calling <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fnmatch.html"><code class="function">fnmatch</code></a>.
</p><p><a id="fnmatch-matcher"></a><strong><code class="code">(POSIX:FNMATCH-MATCHER
   <em class="replaceable"><code>pattern</code></em>)</code>. </strong>This function is a valid value for <a class="link" href="#apropos" title="25.2.10. Functions APROPOS &amp; APROPOS-LIST"><code class="varname">CUSTOM:*APROPOS-MATCHER*</code></a>.
</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>These two functions used to reside in a separate package
<strong class="package"><span class="quote">“<span class="quote">WILDCARD</span>”</span></strong>, which has been now deprecated.
</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="mk-xterm-io"></a>33.2.13. XTerm</h3></div></div></div><p><code class="code">(<a class="link" href="#mk-xterm-io" title="33.2.13. XTerm"><code class="function">POSIX:MAKE-XTERM-IO-STREAM</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> title xterm)</code>
 When running under the <a class="ulink" href="http://www.x.org/" target="_top">X Window System</a>, you can create a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_b.html#bidirectional">bidirectional</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>, which uses a new
 dedicated text window (created by the executable specified by
 the <code class="constant">:XTERM</code> argument which should be compatible
 with <span class="command"><strong>xterm</strong></span> and <span class="command"><strong>rxvt</strong></span>, i.e., accept
 options <code class="option">-n</code>, <code class="option">-T</code>, and <code class="option">-e</code>)
 using the function <a class="link" href="#mk-xterm-io" title="33.2.13. XTerm"><code class="function">POSIX:MAKE-XTERM-IO-STREAM</code></a>: </p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/spefor_setq.html" target="_top"><code class="function">SETQ</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*ERROR-OUTPUT*</code></a>
      (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/spefor_setq.html" target="_top"><code class="function">SETQ</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*DEBUG-IO*</code></a>
            (<a class="link" href="#mk-xterm-io" title="33.2.13. XTerm"><code class="function">POSIX:MAKE-XTERM-IO-STREAM</code></a> :title "clisp errors and debug")))
</pre><p><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> platform only.</span></span></p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="stdio"></a>33.2.14. Standard file input and output</h3></div></div></div><p>We define the type <span class="type">FFI:file</span> = <a class="link" href="#fptr"><code class="classname">FFI:FOREIGN-POINTER</code></a> and
 the following functions:</p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fopen.html"><code class="function">fopen</code></a> <em class="replaceable"><code>filename</code></em>
    <em class="replaceable"><code>mode</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fdopen.html"><code class="function">fdopen</code></a> fd
    <em class="replaceable"><code>mode</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/freopen.html"><code class="function">freopen</code></a> <em class="replaceable"><code>filename</code></em>
    <em class="replaceable"><code>mode</code></em> <em class="replaceable"><code>file</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fclose.html"><code class="function">fclose</code></a>
    <em class="replaceable"><code>file</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fflush.html"><code class="function">fflush</code></a>
    <em class="replaceable"><code>file</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/clearerr.html"><code class="function">clearerr</code></a>
    <em class="replaceable"><code>file</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/feof.html"><code class="function">feof</code></a>
    <em class="replaceable"><code>file</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/ferror.html"><code class="function">ferror</code></a>
    <em class="replaceable"><code>file</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fileno.html"><code class="function">fileno</code></a>
    <em class="replaceable"><code>file</code></em>)</code></td></tr></table><p>call their namesakes defined in <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/stdio.h.html">&lt;<code class="filename">stdio.h</code>&gt;</a>.</p><p>Functions </p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="function">OS:FOPEN</code></td></tr><tr><td><code class="function">OS:FDOPEN</code></td></tr><tr><td><code class="function">OS:FREOPEN</code></td></tr><tr><td><code class="function">OS:FCLOSE</code></td></tr><tr><td><code class="function">OS:FFLUSH</code></td></tr><tr><td><code class="function">OS:FILENO</code></td></tr></table><p> may <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a> an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>.</p><div class="variablelist"><p class="title"><strong>Return values</strong></p><dl class="variablelist"><dt><span class="term"><code class="function">OS:FOPEN</code><br /></span><span class="term"><code class="function">OS:FDOPEN</code></span></dt><dd><span class="type">FFI:file</span> = <a class="link" href="#fptr"><code class="classname">FFI:FOREIGN-POINTER</code></a>
  </dd><dt><span class="term"><code class="function">OS:FREOPEN</code><br /></span><span class="term"><code class="function">OS:FCLOSE</code><br /></span><span class="term"><code class="function">OS:FFLUSH</code><br /></span><span class="term"><code class="function">OS:CLEARERR</code></span></dt><dd>no values (they modify their <em class="replaceable"><code>file</code></em> argument in place)
  </dd><dt><span class="term"><code class="function">OS:FEOF</code><br /></span><span class="term"><code class="function">OS:FERROR</code></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_boolean.html" target="_top"><code class="classname">BOOLEAN</code></a></dd><dt><span class="term"><code class="function">OS:FILENO</code></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> (<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a>)</dd></dl></div><p>We also define 3 constants </p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="constant">OS:STDIN</code></td></tr><tr><td><code class="constant">OS:STDOUT</code></td></tr><tr><td><code class="constant">OS:STDERR</code></td></tr></table><div class="simplesect"><div class="titlepage"><div><div><h4 class="title"><a id="stdio-rationale"></a>Rationale</h4></div></div></div><p><a id="stdio-ffi"></a><strong>Iterface to foreign libraries. </strong>This functionality can be used by <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> <a href="impnotes.html#modules" class="olink">module</a>s which
  interface to functions which use the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> <span class="type">FILE*</span> pointers.
  E.g., <span class="module"><a class="filename" href="#postgresql" title="33.9. PostgreSQL Database Access"><code class="filename">postgresql</code></a></span> has a function <a class="pq" href="http://www.postgresql.org/search/?q=PQtrace"><code class="function">PQtrace</code></a>
  which expects a <span class="type">FILE*</span> argument.
  You can use <code class="function">OS:FOPEN</code>
  and <code class="function">OS:FCLOSE</code> for that.</p><p><a id="stdio-wild"></a><strong>Bypass <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> filename processing. </strong>You can also use this functionality to access files whose
  names are interpreted as wild by <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a>. E.g.,</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET</code></a> ((file (posix:fopen "foo*" "r")))
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_unwind-protect.html" target="_top"><code class="function">UNWIND-PROTECT</code></a>
      (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-open-stream.html" target="_top"><code class="function">WITH-OPEN-STREAM</code></a> (s (<a class="link" href="#make-stream" title="21.9. Function EXT:MAKE-STREAM"><code class="function">EXT:MAKE-STREAM</code></a> (posix:fileno file)))
        (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-line.html" target="_top"><code class="function">READ-LINE</code></a> s))
    (posix:fclose file)))
</pre></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="errno"></a>33.2.15. Error handling</h3></div></div></div><p>To handle errors in foreign functions, the following four
 functions are provided: </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">(POSIX:ERRNO <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>error-code</code></em>)</code></span></dt><dd><p class="simpara">When <em class="replaceable"><code>error-code</code></em> is supplied, <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/errno.html"><code class="varname">errno</code></a> is set (useful
   before a system call which sets <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/errno.html"><code class="varname">errno</code></a> as the only way to report an
   error).</p><p class="simpara">If <em class="replaceable"><code>error-code</code></em> is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_number.html" target="_top"><code class="classname">NUMBER</code></a>, the corresponding <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_keyword.html" target="_top"><code class="classname">KEYWORD</code></a>
   is returned and vice versa.</p><p class="simpara">When <em class="replaceable"><code>error-code</code></em> is not supplied, the current <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/errno.html"><code class="varname">errno</code></a> is
   returned as a keyword if possible, a number otherwise.</p><p class="simpara">When <em class="replaceable"><code>error-code</code></em> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>, all known error codes are
   returned as an <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_a.html#association_list">association list</a>.</p></dd><dt><span class="term"><code class="code">(OS:LAST-ERROR <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
    <em class="replaceable"><code>error-code</code></em>)</code></span></dt><dd><p class="simpara">Just like <code class="function">POSIX:ERRNO</code>,
   but uses <a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=GetLastError"><code class="function">GetLastError</code></a>
   and <a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=SetLastError"><code class="function">SetLastError</code></a> instead
   of <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/errno.html"><code class="varname">errno</code></a>.</p><p class="simpara"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platform only.</span></span></p></dd><dt><span class="term"><code class="code">(POSIX:STRERROR <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
   <em class="replaceable"><code>error-code</code></em>)</code></span></dt><dd><p class="simpara">Return a string description of <em class="replaceable"><code>error-code</code></em>.
   When <em class="replaceable"><code>error-code</code></em> is not supplied, <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/errno.html"><code class="varname">errno</code></a> is used.</p><p class="simpara">This calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/strerror.html"><code class="function">strerror</code></a>.</p></dd><dt><span class="term"><code class="code">(OS:FORMAT-MESSAGE <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
   <em class="replaceable"><code>error-code</code></em>)</code></span></dt><dd><p class="simpara">Just like <code class="function">POSIX:STRERROR</code>,
  but uses <a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=FormatMessage"><code class="function">FormatMessage</code></a>
  and <a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=GetLastError"><code class="function">GetLastError</code></a>.</p><p class="simpara"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platform only.</span></span></p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="misc"></a>33.2.16. Miscellanea</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><a id="clipboard"></a><span class="term"><code class="code">(OS:CLIPBOARD)</code><br /></span><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (OS:CLIPBOARD) <em class="replaceable"><code>object</code></em>)</code></span></dt><dd><p class="simpara">Get
   (using <a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=GetClipboardData"><code class="function">GetClipboardData</code></a>) a set
   (using <a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=SetClipboardData"><code class="function">SetClipboardData</code></a>)
   the windows clipboard.</p><p class="simpara">Return a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>; convert <em class="replaceable"><code>object</code></em> to a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>
   using <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_write-to-_nc-to-string.html" target="_top"><code class="function">PRINC-TO-STRING</code></a>.</p><p class="simpara"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> and <a class="ulink" href="http://cygwin.com/" target="_top"><span class="platform">Cygwin</span></a> platforms only.</span></span></p></dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="i18n-mod"></a>33.3. Internationalization of User Programs</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#ggettext">33.3.1. The GNU gettext</a></span></dt><dd><dl><dt><span class="section"><a href="#domain">33.3.1.1. Domain</a></span></dt><dt><span class="section"><a href="#category">33.3.1.2. Category</a></span></dt><dt><span class="section"><a href="#i18n-example">33.3.1.3. Internationalization Example</a></span></dt></dl></dd><dt><span class="section"><a href="#i18n-locale">33.3.2. Locale</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="ggettext"></a>33.3.1. The <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/gettext/" target="_top">gettext</a></h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#domain">33.3.1.1. Domain</a></span></dt><dt><span class="section"><a href="#category">33.3.1.2. Category</a></span></dt><dt><span class="section"><a href="#i18n-example">33.3.1.3. Internationalization Example</a></span></dt></dl></div><p><a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/gettext/" target="_top">gettext</a> is a set of functions, included in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> or the
<a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> library, which permit looking up translations of strings
through message catalogs. It is also a set of tools which makes the
translation maintenance easy for the translator and the program
maintainer.</p><p>The <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/gettext/" target="_top">gettext</a> functions are available in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> in the
<a class="link" href="#i18n" title="31.4. Internationalization of CLISP"><strong class="package"><span class="quote">“<span class="quote">I18N</span>”</span></strong></a> package, which is <a class="link" href="#re-export" title="11.1.3. Function EXT:RE-EXPORT"><code class="function">EXT:RE-EXPORT</code></a>ed from the <a class="link" href="#ext-pac"><strong class="package"><span class="quote">“<span class="quote">EXT</span>”</span></strong></a>
package.</p><p>This module is present in the <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>base</strong></span></a> <a href="impnotes.html#linkset" class="olink">linking set</a> by default.</p><p>When this module is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a>
 contains the symbol <code class="constant">:I18N</code>.</p><div class="variablelist"><dl class="variablelist"><dt><a id="gettext"></a><span class="term"><code class="code">(<a class="link" href="#gettext"><code class="function">I18N:GETTEXT</code></a>
    <em class="replaceable"><code>MSGID</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <a class="link" href="#domain" title="33.3.1.1. Domain"><em class="replaceable"><code>DOMAIN</code></em></a> <a class="link" href="#category" title="33.3.1.2. Category"><em class="replaceable"><code>CATEGORY</code></em></a>)</code></span></dt><dd>returns the translation of the message <em class="replaceable"><code>MSGID</code></em>,
    in the given <a class="link" href="#domain" title="33.3.1.1. Domain"><em class="replaceable"><code>DOMAIN</code></em></a>, depending on the given <a class="link" href="#category" title="33.3.1.2. Category"><em class="replaceable"><code>CATEGORY</code></em></a>.
    <em class="replaceable"><code>MSGID</code></em> should be an <a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a> string, and is normally the English message.
 </dd><dt><a id="ngettext"></a><span class="term"><code class="code">(<a class="link" href="#ngettext"><code class="function">I18N:NGETTEXT</code></a>
    <em class="replaceable"><code>MSGID</code></em> <em class="replaceable"><code>msgid_plural</code></em>
    <em class="replaceable"><code>n</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <a class="link" href="#domain" title="33.3.1.1. Domain"><em class="replaceable"><code>DOMAIN</code></em></a> <a class="link" href="#category" title="33.3.1.2. Category"><em class="replaceable"><code>CATEGORY</code></em></a>)</code></span></dt><dd>returns the plural form of the translation for of
    <em class="replaceable"><code>MSGID</code></em> and <em class="replaceable"><code>n</code></em> in the given <a class="link" href="#domain" title="33.3.1.1. Domain"><em class="replaceable"><code>DOMAIN</code></em></a>, depending on the given
    <a class="link" href="#category" title="33.3.1.2. Category"><em class="replaceable"><code>CATEGORY</code></em></a>.  <em class="replaceable"><code>MSGID</code></em> and <em class="replaceable"><code>msgid_plural</code></em>
    should be <a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a> strings, and are normally the English singular and
    English plural variant of the message, respectively.
 </dd></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="domain"></a>33.3.1.1. Domain</h4></div></div></div><p>The <a class="link" href="#domain" title="33.3.1.1. Domain"><em class="replaceable"><code>DOMAIN</code></em></a> is a string identifier denoting the program that
is requesting the translation.  The pathname of the message catalog
depends on the <a class="link" href="#domain" title="33.3.1.1. Domain"><em class="replaceable"><code>DOMAIN</code></em></a>: usually it is located at
<code class="filename">TEXTDOMAINDIR/l/LC_MESSAGES/domain.mo</code>, where
<em class="replaceable"><code>l</code></em> is the <a class="ulink" href="http://www.loc.gov/standards/iso639-2/" target="_top">ISO
 639-2</a> code of the language.
The notion of <a class="link" href="#domain" title="33.3.1.1. Domain"><em class="replaceable"><code>DOMAIN</code></em></a> allows several Lisp programs running in the same
image to request translations independently of each other.</p><p><a id="textdomain"></a><strong>Function <a class="link" href="#textdomain" title="Function I18N:TEXTDOMAIN"><code class="function">I18N:TEXTDOMAIN</code></a>. </strong><code class="code">(<a class="link" href="#textdomain" title="Function I18N:TEXTDOMAIN"><code class="function">I18N:TEXTDOMAIN</code></a>)</code> is a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a> that returns the default
 <a class="link" href="#domain" title="33.3.1.1. Domain"><em class="replaceable"><code>DOMAIN</code></em></a>, used when no <a class="link" href="#domain" title="33.3.1.1. Domain"><em class="replaceable"><code>DOMAIN</code></em></a> argument is passed to the <a class="link" href="#gettext"><code class="function">I18N:GETTEXT</code></a> and
 <a class="link" href="#ngettext"><code class="function">I18N:NGETTEXT</code></a> functions.  It is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>able.
<code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="link" href="#textdomain" title="Function I18N:TEXTDOMAIN"><code class="function">I18N:TEXTDOMAIN</code></a>)</code> is usually used
during the startup phase of a program.
Note that the default <a class="link" href="#domain" title="33.3.1.1. Domain"><em class="replaceable"><code>DOMAIN</code></em></a> is not saved in a <a href="impnotes.html#image" class="olink">memory image</a>.
The use of <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="link" href="#textdomain" title="Function I18N:TEXTDOMAIN"><code class="function">I18N:TEXTDOMAIN</code></a>)</code> is
recommended only for programs that are so simple that they will never
need more than one <a class="link" href="#domain" title="33.3.1.1. Domain"><em class="replaceable"><code>DOMAIN</code></em></a>.</p><p><a id="textdomaindir"></a><strong>Function <a class="link" href="#textdomaindir" title="Function I18N:TEXTDOMAINDIR"><code class="function">I18N:TEXTDOMAINDIR</code></a>. </strong><code class="code">(<a class="link" href="#textdomaindir" title="Function I18N:TEXTDOMAINDIR"><code class="function">I18N:TEXTDOMAINDIR</code></a> <a class="link" href="#domain" title="33.3.1.1. Domain"><em class="replaceable"><code>DOMAIN</code></em></a>)</code>
is a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a> that returns the base directory, called
<code class="filename">TEXTDOMAINDIR</code> above, where the message
catalogs for the given <a class="link" href="#domain" title="33.3.1.1. Domain"><em class="replaceable"><code>DOMAIN</code></em></a> are assumed to be installed.
It is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>able.
<code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="link" href="#textdomaindir" title="Function I18N:TEXTDOMAINDIR"><code class="function">I18N:TEXTDOMAINDIR</code></a>)</code> is usually used
during the startup phase of a program, and should be used because only
the program knows where its message catalogs are installed.
Note that the <code class="filename">TEXTDOMAINDIR</code>s
are not saved in a <a href="impnotes.html#image" class="olink">memory image</a>.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="category"></a>33.3.1.2. Category</h4></div></div></div><p>The <a class="link" href="#category" title="33.3.1.2. Category"><em class="replaceable"><code>CATEGORY</code></em></a> argument of the <a class="link" href="#gettext"><code class="function">I18N:GETTEXT</code></a> and <a class="link" href="#ngettext"><code class="function">I18N:NGETTEXT</code></a>
functions denotes which <em class="replaceable"><code><a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap07.html">LOCALE</a></code></em> facet the result should depend on.
The possible values are a platform-dependent subset of
<span class="simplelist"><code class="constant">:LC_ADDRESS</code>, <code class="constant">:LC_ALL</code>, <code class="constant">:LC_COLLATE</code>, <code class="constant">:LC_CTYPE</code>, <code class="constant">:LC_IDENTIFICATION</code>, <code class="constant">:LC_MEASUREMENT</code>, <code class="constant">:LC_MESSAGES</code>, <code class="constant">:LC_MONETARY</code>, <code class="constant">:LC_NAME</code>, <code class="constant">:LC_NUMERIC</code>, <code class="constant">:LC_PAPER</code>, <code class="constant">:LC_TELEPHONE</code>, <code class="constant">:LC_TIME</code></span>
The use of these values is useful for users who have a
character/time/collation/money handling set differently from the usual
message handling.
Note that when a <a class="link" href="#category" title="33.3.1.2. Category"><em class="replaceable"><code>CATEGORY</code></em></a> argument is used, the message catalog
location depends on the <a class="link" href="#category" title="33.3.1.2. Category"><em class="replaceable"><code>CATEGORY</code></em></a>: it will be expected at
<code class="filename">TEXTDOMAINDIR/ll/category/domain.mo</code>.</p></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="i18n-example"></a>33.3.1.3. Internationalization Example</h4></div></div></div><p>A non-internationalized program simulating a restaurant dialogue
might look as follows.</p><p><a id="i18n-non-i"></a><strong>prog.lisp. </strong></p><pre class="programlisting">
(setq n (parse-integer (first <a href="impnotes.html#script-exec" class="olink"><code class="varname">EXT:*ARGS*</code></a>)))

(format t "~A~%" "'Your command, please?', asked the waiter.")

(format t "~@?~%"
          (if (= n 1) "a piece of cake" "~D pieces of cake")
          n)
</pre><p>After being internationalized, all strings are wrapped in
<a class="link" href="#gettext"><code class="function">I18N:GETTEXT</code></a> calls, and <a class="link" href="#ngettext"><code class="function">I18N:NGETTEXT</code></a> is used for plurals.
Also, <a class="link" href="#textdomaindir" title="Function I18N:TEXTDOMAINDIR"><code class="function">I18N:TEXTDOMAINDIR</code></a> is assigned a value; in our case, for simplicity,
the current directory.</p><p><a id="i18n-i"></a><strong>prog.lisp. </strong></p><pre class="programlisting">
(setf (textdomain) "prog")
(setf (textdomaindir "prog") "./")

(setq n (parse-integer (first <a href="impnotes.html#script-exec" class="olink"><code class="varname">EXT:*ARGS*</code></a>)))

(format t "~A~%"
          (gettext "'Your command, please?', asked the waiter."))

(format t "~@?~%"
          (ngettext "a piece of cake" "~D pieces of cake" n)
          n)
</pre><p>For ease of reading, it is customary to define an abbreviation
for the <a class="link" href="#gettext"><code class="function">I18N:GETTEXT</code></a> function.  An underscore is customary.</p><p><a id="i18n-i-abbrev"></a><strong>prog.lisp. </strong></p><pre class="programlisting">
(setf (textdomaindir "prog") "./")
(defun _ (msgid) (gettext msgid "prog"))

(setq n (parse-integer (first <a href="impnotes.html#script-exec" class="olink"><code class="varname">EXT:*ARGS*</code></a>)))

(format t "~A~%"
          (_"'Your command, please?', asked the waiter."))

(format t "~@?~%"
          (ngettext "a piece of cake" "~D pieces of cake" n "prog")
          n)
</pre><p>Now the program's maintainer creates a message catalog template
through the command
</p><pre class="screen">
<strong><code class="prompt">$</code></strong> xgettext -o prog.pot prog.lisp
</pre><p>
</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>xgettext version 0.11 or higher is required here.</p></div><p>The message catalog template looks roughly like this.</p><p><a id="i18n-pot"></a><strong>prog.pot. </strong></p><pre class="programlisting">
msgid "'Your command, please?', asked the waiter."
msgstr ""

msgid "a piece of cake"
msgid_plural "%d pieces of cake"
msgstr[0] ""
msgstr[1] ""
</pre><p>Then a French translator creates a French message catalog</p><p><a id="i18n-fr-po"></a><strong>prog.fr.po. </strong></p><pre class="programlisting">
msgid ""
msgstr ""
"Content-Type: text/plain; charset=ISO-8859-1\n"
"Plural-Forms: nplurals=2; plural=(n &gt; 1);\n"

msgid "'Your command, please?', asked the waiter."
msgstr "«Votre commande, s'il vous plait», dit le garçon."

# Les gateaux allemands sont les meilleurs du monde.
msgid "a piece of cake"
msgid_plural "%d pieces of cake"
msgstr[0] "un morceau de gateau"
msgstr[1] "%d morceaux de gateau"
</pre><p>and sends it to the program's maintainer.</p><p>The program's maintainer compiles the catalog as follows:
</p><pre class="screen">
<strong><code class="prompt">$</code></strong> mkdir -p ./fr/LC_MESSAGES
<strong><code class="prompt">$</code></strong> msgfmt -o ./fr/LC_MESSAGES/prog.mo prog.fr.po
</pre><p>When a user in a french <em class="replaceable"><code><a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap07.html">LOCALE</a></code></em> then runs the program
</p><pre class="screen">
<strong><code class="prompt">$</code></strong> clisp prog.lisp 2
</pre><p>
she will get the output
</p><pre class="screen">
    «Votre commande, s'il vous plait», dit le garçon.
    2 morceaux de gateau
</pre><p>
</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="i18n-locale"></a>33.3.2. Locale</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><a id="set-locale"></a><span class="term"><code class="code">(<a class="link" href="#set-locale"><code class="function">I18N:SET-LOCALE</code></a>
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <a class="link" href="#category" title="33.3.1.2. Category"><em class="replaceable"><code>CATEGORY</code></em></a> <em class="replaceable"><code><a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap07.html">LOCALE</a></code></em>)</code></span></dt><dd><p class="simpara">This is an interface to
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/setlocale.html"><code class="function">setlocale</code></a>.</p><p class="simpara">When <em class="replaceable"><code><a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap07.html">LOCALE</a></code></em> is missing or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, return the current one.</p><p class="simpara">When <a class="link" href="#category" title="33.3.1.2. Category"><em class="replaceable"><code>CATEGORY</code></em></a> is missing or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, return all categories
   as a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>.</p></dd><dt><a id="locale-conv"></a><span class="term"><code class="code">(<a class="link" href="#locale-conv"><code class="function">I18N:LOCALE-CONV</code></a>)</code></span></dt><dd><p class="simpara">This is an interface to
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/localeconv.html"><code class="function">localeconv</code></a>.</p><p class="simpara">Returns a <span class="type">I18N:LOCALE-CONV</span>
   structure.</p></dd><dt><a id="lang-info"></a><span class="term"><code class="code">(<a class="link" href="#lang-info"><code class="function">I18N:LANGUAGE-INFORMATION</code></a>
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>item</code></em>)</code></span></dt><dd><p class="simpara">This is an interface to
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/nl_langinfo.html"><code class="function">nl_langinfo</code></a> (<a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>)
   and <a class="win32" href="https://social.msdn.microsoft.com/search/en-US/windows?query=GetLocaleInfo"><code class="function">GetLocaleInfo</code></a> (<a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>).</p><p class="simpara">When <em class="replaceable"><code>item</code></em> is missing or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>,
   return all available information as a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>.</p></dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="regexp-mod"></a>33.4. POSIX Regular Expressions</h2></div></div></div><div class="list-of-examples"><p><strong>List of Examples</strong></p><dl><dt>33.1. <a href="#ex-re-match"><code class="function">REGEXP:MATCH</code></a></dt><dt>33.2. <a href="#ex-re-quote"><code class="function">REGEXP:REGEXP-QUOTE</code></a></dt><dt>33.3. <a href="#re-count-shell-users">Count unix shell users</a></dt></dl></div><p>The <a class="link" href="#regexp-mod" title="33.4. POSIX Regular Expressions"><strong class="package"><span class="quote">“<span class="quote">REGEXP</span>”</span></strong></a> module implements the <a class="ulink" href="http://www.opengroup.org/austin/papers/posix_faq.html" target="_top"><span class="platform">POSIX</span></a>
 <a class="ulink" href="regexp.html" target="_top">regular expressions</a>
matching by calling the standard <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> system facilities.
The syntax of these <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html">regular expression</a>s is described in many places,
such as your local <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/regex.h.html">&lt;<code class="filename">regex.h</code>&gt;</a> manual and <a class="ulink" href="http://www.gnu.org/software/emacs/" target="_top">Emacs</a> info pages.</p><p>This module is present in the <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>base</strong></span></a> <a href="impnotes.html#linkset" class="olink">linking set</a> by default.</p><p>When this module is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a>
 contains the symbol <code class="constant">:REGEXP</code>.</p><div class="variablelist"><a id="regexp-api"></a><p class="title"><strong>Regular Expression API</strong></p><dl class="variablelist"><dt><a id="re-match"></a><span class="term"><code class="code">(<a class="link" href="#re-match"><code class="function">REGEXP:MATCH</code></a> <em class="replaceable"><code>pattern</code></em>
   <em class="replaceable"><code>string</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> (<code class="constant">:START</code> 0) <code class="constant">:END</code> <a class="link" href="#re-cflags"><code class="constant">:EXTENDED</code> <code class="constant">:IGNORE-CASE</code> <code class="constant">:NEWLINE</code> <code class="constant">:NOSUB</code></a>
   <a class="link" href="#re-eflags"><code class="constant">:NOTBOL</code> <code class="constant">:NOTEOL</code></a>)</code></span></dt><dd><p>This macro returns as first value a <a class="link" href="#regexp-api" title="Regular Expression API"><code class="classname">REGEXP:MATCH</code></a> structure
  containing the indices of the start and end of the first match for the
  <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html">regular expression</a> <em class="replaceable"><code>pattern</code></em> in <em class="replaceable"><code>string</code></em>; or no values if there is no match.
  Additionally, a <a class="link" href="#regexp-api" title="Regular Expression API"><code class="classname">REGEXP:MATCH</code></a> structure is returned for every matched
  <code class="literal">"\(...\)"</code> group in <em class="replaceable"><code>pattern</code></em>, in the
  order that the open parentheses appear in <em class="replaceable"><code>pattern</code></em>.
  If <em class="replaceable"><code>start</code></em> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, the search starts at that index in <em class="replaceable"><code>string</code></em>.
  If <em class="replaceable"><code>end</code></em> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, only <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_subseq.html" target="_top"><code class="function">SUBSEQ</code></a> <em class="replaceable"><code>string</code></em> <em class="replaceable"><code>start</code></em>
  <em class="replaceable"><code>end</code></em>)</code> is considered.
  </p><div class="example"><a id="ex-re-match"></a><p class="title"><strong>Example 33.1. <a class="link" href="#re-match"><code class="function">REGEXP:MATCH</code></a></strong></p><div class="example-contents"><pre class="programlisting">
(<a class="link" href="#re-match"><code class="function">REGEXP:MATCH</code></a> "quick" "The quick brown fox jumped quickly.")
⇒ <code class="computeroutput">#S(<a class="link" href="#regexp-api" title="Regular Expression API"><code class="classname">REGEXP:MATCH</code></a> :START 4 :END 9)</code>
(<a class="link" href="#re-match"><code class="function">REGEXP:MATCH</code></a> "quick" "The quick brown fox jumped quickly." :start 8)
⇒ <code class="computeroutput">#S(<a class="link" href="#regexp-api" title="Regular Expression API"><code class="classname">REGEXP:MATCH</code></a> :START 27 :END 32)</code>
(<a class="link" href="#re-match"><code class="function">REGEXP:MATCH</code></a> "quick" "The quick brown fox jumped quickly." :start 8 :end 30)
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></code>
(<a class="link" href="#re-match"><code class="function">REGEXP:MATCH</code></a> "\\([a-z]*\\)[0-9]*\\(bar\\)" "foo12bar")
⇒ <code class="computeroutput">#S(<a class="link" href="#regexp-api" title="Regular Expression API"><code class="classname">REGEXP:MATCH</code></a> :START 0 :END 8)</code> ;
⇒ <code class="computeroutput">#S(<a class="link" href="#regexp-api" title="Regular Expression API"><code class="classname">REGEXP:MATCH</code></a> :START 0 :END 3)</code> ;
⇒ <code class="computeroutput">#S(<a class="link" href="#regexp-api" title="Regular Expression API"><code class="classname">REGEXP:MATCH</code></a> :START 5 :END 8)</code>
</pre></div></div><p><br class="example-break" />
</p></dd><dt><a id="re-match-access"></a><span class="term"><code class="code">(<a class="link" href="#re-match-access"><code class="function">REGEXP:MATCH-START</code></a> <em class="replaceable"><code>match</code></em>)</code><br /></span><span class="term"><code class="code">(<a class="link" href="#re-match-access"><code class="function">REGEXP:MATCH-END</code></a> <em class="replaceable"><code>match</code></em>)</code></span></dt><dd>Return the start and end the <em class="replaceable"><code>match</code></em>; <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>-able.
</dd><dt><a id="re-match-string"></a><span class="term"><code class="code">(<a class="link" href="#re-match-string"><code class="function">REGEXP:MATCH-STRING</code></a> <em class="replaceable"><code>string</code></em> <em class="replaceable"><code>match</code></em>)</code></span></dt><dd>Extracts the substring of <em class="replaceable"><code>string</code></em> corresponding
   to the given pair of start and end indices of <em class="replaceable"><code>match</code></em>.
   The result is shared with <em class="replaceable"><code>string</code></em>.
   If you want a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_f.html#fresh">fresh</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>, use <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_copy-seq.html" target="_top"><code class="function">COPY-SEQ</code></a> or
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_coerce.html" target="_top"><code class="function">COERCE</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-string.html" target="_top"><code class="classname">SIMPLE-STRING</code></a>.</dd><dt><a id="re-regexp-quote"></a><span class="term"><code class="code">(<a class="link" href="#re-regexp-quote"><code class="function">REGEXP:REGEXP-QUOTE</code></a>
   <em class="replaceable"><code>string</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>extended</code></em>)</code></span></dt><dd><p>This function returns a <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html">regular expression</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>
  that matches exactly <em class="replaceable"><code>string</code></em> and nothing else.
  This allows you to request an exact string match when calling a
  function that wants a <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html">regular expression</a>.
  </p><div class="example"><a id="ex-re-quote"></a><p class="title"><strong>Example 33.2. <a class="link" href="#re-regexp-quote"><code class="function">REGEXP:REGEXP-QUOTE</code></a></strong></p><div class="example-contents"><pre class="programlisting">
(regexp-quote "^The cat$")
⇒ <code class="computeroutput">"\\^The cat\\$"</code></pre></div></div><p><br class="example-break" />
  One use of <a class="link" href="#re-regexp-quote"><code class="function">REGEXP:REGEXP-QUOTE</code></a> is to combine an exact string match with
  context described as a <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html">regular expression</a>.
  When <em class="replaceable"><code>extended</code></em> is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, also
  quote <span class="keysym">#\+</span> and <span class="keysym">#\?</span>.
</p></dd><dt><a id="re-regexp-compile"></a><span class="term"><code class="code">(<a class="link" href="#re-regexp-compile"><code class="function">REGEXP:REGEXP-COMPILE</code></a>
   <em class="replaceable"><code>string</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <a class="link" href="#re-cflags"><code class="constant">:EXTENDED</code> <code class="constant">:IGNORE-CASE</code> <code class="constant">:NEWLINE</code> <code class="constant">:NOSUB</code></a>)</code></span></dt><dd>Compile the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html">regular expression</a> <em class="replaceable"><code>string</code></em> into an
  object suitable for <a class="link" href="#re-regexp-exec"><code class="function">REGEXP:REGEXP-EXEC</code></a>.</dd><dt><a id="re-regexp-exec"></a><span class="term"><code class="code">(<a class="link" href="#re-regexp-exec"><code class="function">REGEXP:REGEXP-EXEC</code></a>
   <em class="replaceable"><code>pattern</code></em> <em class="replaceable"><code>string</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:RETURN-TYPE</code>
   (<code class="constant">:START</code> 0) <code class="constant">:END</code> <a class="link" href="#re-eflags"><code class="constant">:NOTBOL</code> <code class="constant">:NOTEOL</code></a>)</code></span></dt><dd><p class="simpara">Execute the <em class="replaceable"><code>pattern</code></em>, which must be a compiled
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html">regular expression</a> returned by <a class="link" href="#re-regexp-compile"><code class="function">REGEXP:REGEXP-COMPILE</code></a>, against the appropriate
   portion of the <em class="replaceable"><code>string</code></em>.</p><p class="simpara">Returns <a class="link" href="#regexp-api" title="Regular Expression API"><code class="classname">REGEXP:MATCH</code></a> structures as <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_m.html#multiple_values">multiple values</a> (one for each
   subexpression which successfully matched and one for the whole pattern).
  </p><p class="simpara">If <code class="constant">:RETURN-TYPE</code> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> (or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a>), the
   <a class="link" href="#regexp-api" title="Regular Expression API"><code class="classname">REGEXP:MATCH</code></a> structures are returned as a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> (or a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a>) instead.
   Also, if there are more than <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_multip_values-limit.html" target="_top"><code class="constant">MULTIPLE-VALUES-LIMIT</code></a> <a class="link" href="#regexp-api" title="Regular Expression API"><code class="classname">REGEXP:MATCH</code></a> structures
   to return, a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> is returned instead of <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_m.html#multiple_values">multiple values</a>.
   If <code class="constant">:RETURN-TYPE</code> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_boolean.html" target="_top"><code class="classname">BOOLEAN</code></a>, return <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> as an indicator
   of success or failure, but do <span class="strong"><strong>not</strong></span> allocate anything.
</p></dd><dt><a id="re-regexp-split"></a><span class="term"><code class="code">(<a class="link" href="#re-regexp-split"><code class="function">REGEXP:REGEXP-SPLIT</code></a>
     <em class="replaceable"><code>pattern</code></em> <em class="replaceable"><code>string</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> (<code class="constant">:START</code> 0) <code class="constant">:END</code>
     <a class="link" href="#re-cflags"><code class="constant">:EXTENDED</code> <code class="constant">:IGNORE-CASE</code> <code class="constant">:NEWLINE</code> <code class="constant">:NOSUB</code></a> <a class="link" href="#re-eflags"><code class="constant">:NOTBOL</code> <code class="constant">:NOTEOL</code></a>)</code></span></dt><dd>Return a list of substrings of <em class="replaceable"><code>string</code></em> (all
  sharing the structure with <em class="replaceable"><code>string</code></em>) separated by <em class="replaceable"><code>pattern</code></em> (a
  <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html">regular expression</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> or a return value of <a class="link" href="#re-regexp-compile"><code class="function">REGEXP:REGEXP-COMPILE</code></a>)
 </dd><dt><a id="re-with-loop-split"></a><span class="term"><code class="code">(<a class="link" href="#re-with-loop-split"><code class="function">REGEXP:WITH-LOOP-SPLIT</code></a>
     (<em class="replaceable"><code>variable</code></em> <em class="replaceable"><code>stream</code></em> <em class="replaceable"><code>pattern</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> (<code class="constant">:START</code> 0) <code class="constant">:END</code>
     <a class="link" href="#re-cflags"><code class="constant">:EXTENDED</code> <code class="constant">:IGNORE-CASE</code> <code class="constant">:NEWLINE</code> <code class="constant">:NOSUB</code></a> <a class="link" href="#re-eflags"><code class="constant">:NOTBOL</code> <code class="constant">:NOTEOL</code></a>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> <em class="replaceable"><code>body</code></em>)</code></span></dt><dd>Read lines from <em class="replaceable"><code>stream</code></em>, split them with
  <a class="link" href="#re-regexp-split"><code class="function">REGEXP:REGEXP-SPLIT</code></a> on <em class="replaceable"><code>pattern</code></em>, and bind the resulting list to
  <em class="replaceable"><code>variable</code></em>.</dd><dt><a id="re-cflags"></a><span class="term"><a class="link" href="#re-cflags"><code class="constant">:EXTENDED</code> <code class="constant">:IGNORE-CASE</code> <code class="constant">:NEWLINE</code> <code class="constant">:NOSUB</code></a></span></dt><dd>These options control compilation of a pattern.
   See <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/regex.h.html">&lt;<code class="filename">regex.h</code>&gt;</a> for their meaning.</dd><dt><a id="re-eflags"></a><span class="term"><a class="link" href="#re-eflags"><code class="constant">:NOTBOL</code> <code class="constant">:NOTEOL</code></a></span></dt><dd>These options control execution of a pattern.
   See <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/regex.h.html">&lt;<code class="filename">regex.h</code>&gt;</a> for their meaning.</dd><dt><a id="re-matcher"></a><span class="term"><a class="link" href="#re-matcher"><code class="function">REGEXP:REGEXP-MATCHER</code></a></span></dt><dd>A valid value for <a class="link" href="#apropos" title="25.2.10. Functions APROPOS &amp; APROPOS-LIST"><code class="varname">CUSTOM:*APROPOS-MATCHER*</code></a>.
   This will work only when your <em class="replaceable"><code><a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap07.html">LOCALE</a></code></em> is <a class="link" href="#charset-UTF-8"><code class="constant">CHARSET:UTF-8</code></a>
   because <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> uses <a class="link" href="#charset-UTF-8"><code class="constant">CHARSET:UTF-8</code></a> internally and <a class="ulink" href="http://www.opengroup.org/austin/papers/posix_faq.html" target="_top"><span class="platform">POSIX</span></a> constrains
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/regex.h.html">&lt;<code class="filename">regex.h</code>&gt;</a> to use the current <em class="replaceable"><code><a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap07.html">LOCALE</a></code></em>.</dd></dl></div><div class="example"><a id="re-count-shell-users"></a><p class="title"><strong>Example 33.3. Count unix shell users</strong></p><div class="example-contents"><p>The following code computes the number of people who use a
 particular shell:</p><pre class="programlisting">
#!/usr/bin/clisp -C
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_use-package.html" target="_top"><code class="function">USE-PACKAGE</code></a> "REGEXP")
(let ((h (make-hash-table :test #'equal :size 10)) (n 0))
  (with-open-file (f (or (first <a href="impnotes.html#script-exec" class="olink"><code class="varname">EXT:*ARGS*</code></a>) "/etc/passwd"))
    (with-loop-split (s f (s f (or (second <a href="impnotes.html#script-exec" class="olink"><code class="varname">EXT:*ARGS*</code></a>) ":")))
      (incf (gethash (seventh s) h 0))))
  (with-hash-table-iterator (i h)
    (loop (multiple-value-bind (r k v) (i)
            (unless r (return))
            (format t "[~d] ~s~30t== ~5:d~%" (incf n) k v)))))
</pre><p>For comparison, the same (almost - except for the nice output formatting)
can be done by the following <a class="ulink" href="http://www.perl.com" target="_top"><span class="command"><strong>Perl</strong></span></a>:</p><pre class="programlisting">
#!/usr/bin/perl -w

use diagnostics;
use strict;

my $IN = $ARGV[0] || "/etc/passwd";
open(INF,"≤ $IN") or die "$0: cannot read file [$IN]: $!\n";
my %hash;
while (≤INF≥) {
  chop;
  my @all = split($ARGV[1] || ":");
  $hash{$all[6] || ""}++;
}
my $ii = 0;
for my $kk (keys(%hash)) {
  print "[",++$ii,"] \"",$kk,"\"  -- ",$hash{$kk},"\n";
}
close(INF);
</pre></div></div><br class="example-break" /></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="readline-mod"></a>33.5. Advanced Readline and History Functionality</h2></div></div></div><p>The <strong class="package"><span class="quote">“<span class="quote">READLINE</span>”</span></strong> module exports most
 of the <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://tiswww.case.edu/php/chet/readline/readline.html" target="_top">readline</a> functions using <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>.</p><p>This module is present even in the <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>base</strong></span></a> <a href="impnotes.html#linkset" class="olink">linking set</a> by default
 on platforms where both <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://tiswww.case.edu/php/chet/readline/readline.html" target="_top">readline</a> and <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> are available.</p><p>When this module is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a>
 contains the symbol <code class="constant">:READLINE</code>.</p><p>See <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/readline/test.tst"><code class="filename">modules/readline/test.tst</code></a>
 for sample usage.</p><div class="variablelist"><p class="title"><strong>Lisp-level Functionality</strong></p><dl class="variablelist"><dt><span class="term"><code class="varname">READLINE:*READLINE-INPUT-STREAM*</code></span></dt><dd>A <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> (see <a class="xref" href="#stream-buffer" title="21.17. Functions EXT:MAKE-BUFFERED-INPUT-STREAM and EXT:MAKE-BUFFERED-OUTPUT-STREAM">Section 21.17, “Functions   <code class="function">EXT:MAKE-BUFFERED-INPUT-STREAM</code>
    and   <code class="function">EXT:MAKE-BUFFERED-OUTPUT-STREAM</code>
     ”</a>)
  that receives user input using <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://tiswww.case.edu/php/chet/readline/readline.html" target="_top">readline</a> and the standard <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
  <a class="link" href="#prompt" title="31.9. The Prompt">prompt</a>.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="gdbm"></a>33.6. GDBM - The GNU database manager</h2></div></div></div><p>This is an interface to the <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/gdbm/" target="_top">DataBase Manager</a>, which extends the standard
 <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/ndbm.h.html">&lt;<code class="filename">ndbm.h</code>&gt;</a>.</p><p>When this module is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a> contains the
 symbol <code class="constant">:GDBM</code>.</p><p>See <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/gdbm/test.tst"><code class="filename">modules/gdbm/test.tst</code></a>
 for sample usage.</p><div class="variablelist"><a id="gdbm-api"></a><p class="title"><strong>GDBM module API</strong></p><dl class="variablelist"><dt><a id="gdbm-version"></a><span class="term"><code class="code">(GDBM:GDBM-VERSION)</code></span></dt><dd><p>Return the version string.</p></dd><dt><a id="gdbm-open"></a><span class="term"><code class="code">(GDBM:GDBM-OPEN <em class="replaceable"><code>filename</code></em>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :BLOCKSIZE :READ-WRITE :OPTION :MODE :DEFAULT-KEY-TYPE
    :DEFAULT-VALUE-TYPE)</code></span></dt><dd><p>Open <em class="replaceable"><code>filename</code></em> database file.
    The return value is a <span class="type">GDBM</span> structure.
    <code class="constant">:READ-WRITE</code> can have one of following values:
    </p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="constant">:READER</code></td></tr><tr><td><code class="constant">:WRITER</code></td></tr><tr><td><code class="constant">:WRCREAT</code></td></tr><tr><td><code class="constant">:NEWDB</code></td></tr></table><p>
    and <code class="constant">:OPTION</code> is one of
    </p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="constant">:SYNC</code></td></tr><tr><td><code class="constant">:NOLOCK</code></td></tr><tr><td><code class="constant">:FAST</code></td></tr></table><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> can store and retrieve values of the
    following types:</p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a></td></tr><tr><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> (meaning anything that can be <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_coerce.html" target="_top"><code class="function">COERCE</code></a>d to
      <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8))</code></span>)</td></tr><tr><td><span class="type"><code class="literal">EXT:32BIT-VECTOR</code></span> (meaning
      <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 32)</code></span>)</code></span>)</td></tr><tr><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a></td></tr><tr><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SINGLE-FLOAT</code></a></td></tr><tr><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">DOUBLE-FLOAT</code></a></td></tr></table><p>
    and <code class="constant">:DEFAULT-KEY-TYPE</code>
    and <code class="constant">:DEFAULT-VALUE-TYPE-TYPE</code> should be one of
    those.  If not specified (or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>), the <code class="constant">:TYPE</code>
    argument is required in the access functions below.</p><p>If <em class="replaceable"><code>filename</code></em> is actually an existing <span class="type">GDBM</span> structure,
    then it is re-opened (if it has been closed), and returned as is.</p><p>The return value is <a class="link" href="#final" title="31.8. Finalization"><code class="function">EXT:FINALIZE</code></a>d with
    <a class="link" href="#gdbm-close"><code class="function">GDBM-CLOSE</code></a>.</p></dd><dt><a id="gdbm-default-types"></a><span class="term"><code class="code">(GDBM:GDBM-DEFAULT-KEY-TYPE <em class="replaceable"><code>db</code></em>)</code><br /></span><span class="term"><code class="code">(GDBM:GDBM-DEFAULT-VALUE-TYPE <em class="replaceable"><code>db</code></em>)</code></span></dt><dd><p>Return the default data conversion types.</p></dd><dt><a id="gdbm-close"></a><span class="term"><code class="code">(GDBM:GDBM-CLOSE <em class="replaceable"><code>db</code></em>)</code></span></dt><dd>Close the database.
 </dd><dt><a id="gdbm-open-p"></a><span class="term"><code class="code">(GDBM:GDBM-OPEN-P <em class="replaceable"><code>db</code></em>)</code></span></dt><dd><p class="simpara">Check whether <em class="replaceable"><code>db</code></em> has been already closed.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>Only the above functions accept closed databases,
     the following functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>s an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> when passed a closed database.
 </p></div></dd><dt><a id="gdbm-store"></a><span class="term"><code class="code">(GDBM:GDBM-STORE <em class="replaceable"><code>db</code></em> <em class="replaceable"><code>key</code></em> <em class="replaceable"><code>contents</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    :FLAG)</code></span></dt><dd><p><em class="replaceable"><code>db</code></em> is the <span class="type">GDBM</span> structure returned by
    <a class="link" href="#gdbm-open"><code class="function">GDBM-OPEN</code></a>.
    <em class="replaceable"><code>key</code></em> is the key datum.
    <em class="replaceable"><code>contents</code></em> is the data to be associated with the key.
    <code class="constant">:FLAG</code> can have one of following values:
    </p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="constant">:INSERT</code></td></tr><tr><td><code class="constant">:REPLACE</code></td></tr></table><p>
 </p></dd><dt><a id="gdbm-fetch"></a><span class="term"><code class="code">(GDBM:GDBM-FETCH <em class="replaceable"><code>db</code></em> <em class="replaceable"><code>key</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    (TYPE (GDBM:GDBM-DEFAULT-VALUE-TYPE <em class="replaceable"><code>db</code></em>)))</code></span></dt><dd>Search the database.
    The <code class="constant">:TYPE</code> argument specifies the return type.
 </dd><dt><a id="gdbm-delete"></a><span class="term"><code class="code">(GDBM:GDBM-DELETE <em class="replaceable"><code>db</code></em> <em class="replaceable"><code>key</code></em>)</code></span></dt><dd>Delete <em class="replaceable"><code>key</code></em> and its contents.
 </dd><dt><a id="gdbm-exists"></a><span class="term"><code class="code">(GDBM:GDBM-EXISTS <em class="replaceable"><code>db</code></em> <em class="replaceable"><code>key</code></em>)</code></span></dt><dd>Search data without retrieving it.
 </dd><dt><a id="gdbm-firstkey"></a><span class="term"><code class="code">(GDBM:GDBM-FIRSTKEY <em class="replaceable"><code>db</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    (TYPE (GDBM:GDBM-DEFAULT-KEY-TYPE <em class="replaceable"><code>db</code></em>)))</code></span></dt><dd>Return the key of the first entry, as <code class="constant">:TYPE</code>.
    If the database has no entries, the return value is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
 </dd><dt><a id="gdbm-nextkey"></a><span class="term"><code class="code">(GDBM:GDBM-NEXTKEY <em class="replaceable"><code>db</code></em> <em class="replaceable"><code>key</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    (TYPE (GDBM:GDBM-DEFAULT-KEY-TYPE <em class="replaceable"><code>db</code></em>)))</code></span></dt><dd>Return the key that follows <em class="replaceable"><code>key</code></em>, as <code class="constant">:TYPE</code>,
    or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if there are no further entries.
 </dd><dt><a id="gdbm-reorganize"></a><span class="term"><code class="code">(GDBM:GDBM-REORGANIZE <em class="replaceable"><code>db</code></em>)</code></span></dt><dd>Reorganize the database.
 </dd><dt><a id="gdbm-sync"></a><span class="term"><code class="code">(GDBM:GDBM-SYNC <em class="replaceable"><code>db</code></em>)</code></span></dt><dd>Syncronize the in-memory state of the database to
    the disk file.</dd><dt><a id="gdbm-setopt"></a><span class="term"><code class="code">(GDBM:GDBM-SETOPT <em class="replaceable"><code>db</code></em> <em class="replaceable"><code>option</code></em> <em class="replaceable"><code>value</code></em>)</code></span></dt><dd><p>Set options on an already open database.
    <em class="replaceable"><code>option</code></em> is one of following:
    </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:CACHESIZE</code></span></dt><dd>set the size of the internal bucket cache.
        (default is 100)</dd><dt><span class="term"><code class="constant">:FASTMODE</code></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> (obsolete)
     </dd><dt><span class="term"><code class="constant">:SYNCMODE</code></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></dd><dt><span class="term"><code class="constant">:CENTFREE</code></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></dd><dt><span class="term"><code class="constant">:COALESCEBLKS</code></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></dd><dt><span class="term"><code class="constant">:DEFAULT-VALUE-TYPE</code><br /></span><span class="term"><code class="constant">:DEFAULT-KEY-TYPE</code></span></dt><dd>see
        <a class="link" href="#gdbm-open"><code class="function">GDBM-OPEN</code></a>
     </dd></dl></div></dd><dt><a id="gdbm-file-size"></a><span class="term"><code class="code">(GDBM:GDBM-FILE-SIZE <em class="replaceable"><code>db</code></em>)</code></span></dt><dd>Return the underlying file size using
    <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/lseek.html"><code class="function">lseek</code></a>.</dd><dt><a id="gdbm-do-db"></a><span class="term"><code class="code">(GDBM:DO-DB (<em class="replaceable"><code>key</code></em> <em class="replaceable"><code>db</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>options</code></em>)
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> <em class="replaceable"><code>body</code></em>)</code></span></dt><dd>Iterate over the database keys, <em class="replaceable"><code>options</code></em> are
    passed to <code class="function">GDBM-FIRSTKEY</code>
    and <code class="function">GDBM-NEXTKEY</code>.
    <em class="replaceable"><code>body</code></em> is passed to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_loop.html" target="_top"><code class="function">LOOP</code></a>, so you can use all the standard loop
    contructs, e.g., <code class="code">(do-db (k db) :collect (list k (gdbm-fetch
     k)))</code> will convert the database to an <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_a.html#association_list">association list</a>.
 </dd><dt><a id="gdbm-with-open-db"></a><span class="term"><code class="code">(GDBM:WITH-OPEN-DB (<em class="replaceable"><code>db</code></em> <em class="replaceable"><code>filename</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>options</code></em>)
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> <em class="replaceable"><code>body</code></em>)</code></span></dt><dd>Open the <em class="replaceable"><code>filename</code></em>, execute the <em class="replaceable"><code>body</code></em>, close
    the database.</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="berkeley-db"></a>33.7. Berkeley DB access</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#bdb-objects">33.7.1. Berkeley-DB Objects</a></span></dt><dt><span class="section"><a href="#bdb-close">33.7.2. Closing handles</a></span></dt><dt><span class="section"><a href="#bdb-db-environment">33.7.3. Database Environment</a></span></dt><dt><span class="section"><a href="#bdb-environment-config">33.7.4. Environment Configuration</a></span></dt><dt><span class="section"><a href="#bdb-operations">33.7.5. Database Operations</a></span></dt><dt><span class="section"><a href="#bdb-db-config">33.7.6. Database Configuration</a></span></dt><dt><span class="section"><a href="#bdb-cursor">33.7.7. Database Cursor Operations</a></span></dt><dt><span class="section"><a href="#bdb-lock">33.7.8. Lock Subsystem</a></span></dt><dt><span class="section"><a href="#bdb-log">33.7.9. Log Subsystem</a></span></dt><dd><dl><dt><span class="section"><a href="#bdb-log-cursor">33.7.9.1. Log Cursor Operations</a></span></dt><dt><span class="section"><a href="#bdb-log-seq">33.7.9.2. Log Sequence Numbers</a></span></dt></dl></dd><dt><span class="section"><a href="#bdb-mem-pool">33.7.10. Memory Pool Subsystem</a></span></dt><dt><span class="section"><a href="#bdb-replication">33.7.11. Replication</a></span></dt><dt><span class="section"><a href="#bdb-sequences">33.7.12. Sequences</a></span></dt><dt><span class="section"><a href="#bdb-transaction">33.7.13. Transaction Subsystem</a></span></dt></dl></div><p>This interface to <a class="ulink" href="http://www.oracle.com/technetwork/products/berkeleydb/overview/index.html" target="_top">Berkeley DB</a>
 from <a class="ulink" href="http://en.wikipedia.org/wiki/Sleepycat_Software" target="_top">Sleepycat
  Software</a>/<a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> exports most functions in the official
 <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> API.  Supported versions:</p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="bdb" href="http://download.oracle.com/otndocs/products/berkeleydb/html/changelog_4_2.html">4.2</a></td></tr><tr><td><a class="bdb" href="http://download.oracle.com/otndocs/products/berkeleydb/html/changelog_4_3.html">4.3</a></td></tr><tr><td><a class="bdb" href="http://download.oracle.com/otndocs/products/berkeleydb/html/changelog_4_4.html">4.4</a></td></tr><tr><td><a class="bdb" href="http://download.oracle.com/otndocs/products/berkeleydb/html/changelog_4_5.html">4.5</a></td></tr><tr><td><a class="bdb" href="http://download.oracle.com/otndocs/products/berkeleydb/html/changelog_4_6.html">4.6</a></td></tr><tr><td><a class="bdb" href="http://download.oracle.com/otndocs/products/berkeleydb/html/changelog_4_7.html">4.7</a></td></tr><tr><td><a class="bdb" href="http://download.oracle.com/otndocs/products/berkeleydb/html/changelog_4_8.html">4.8</a></td></tr><tr><td><a class="bdb" href="http://download.oracle.com/otndocs/products/berkeleydb/html/changelog_5_3.html">5.3</a></td></tr></table><p>When this module is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a> contains the
 symbol <code class="constant">:BERKELEY-DB</code>.</p><p>See <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/berkeley-db/test.tst"><code class="filename">modules/berkeley-db/test.tst</code></a>
 for sample usage.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>The symbol names do evolve with new Berkeley DB releases.
  E.g., version 4.3 introduced <code class="constant">DB_DSYNC_LOG</code> which
  was renamed to <code class="constant">DB_LOG_DSYNC</code> in version 4.7.
  The corresponding Lisp symbol was renamed from
  <code class="constant">:DSYNC-LOG</code> to <code class="constant">:LOG-DSYNC</code>
  when support for version 4.7 was added.
  This means that we always use Lisp names which correspond to the
  <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> names in the latest Berkeley DB release, even though we keep suport
  for older releases.
  This is convenient because the online documentation to which this
  manual refers documents the latest Berkeley DB release.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="bdb-objects"></a>33.7.1. Berkeley-DB Objects</h3></div></div></div><p>Thie module exports the following opaque <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_structure-object.html" target="_top"><code class="classname">STRUCTURE-OBJECT</code></a> types:
 </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="type">BDB:DBE</span></span></dt><dd>environment handle</dd><dt><span class="term"><span class="type">BDB:DB</span></span></dt><dd>database handle</dd><dt><span class="term"><span class="type">BDB:DBC</span></span></dt><dd>cursor handle</dd><dt><span class="term"><span class="type">BDB:TXN</span></span></dt><dd>transaction handle</dd><dt><span class="term"><span class="type">BDB:LOGC</span></span></dt><dd>log cursor handle</dd><dt><span class="term"><span class="type">BDB:MPOOLFILE</span></span></dt><dd>memory pool file handle</dd><dt><span class="term"><span class="type">BDB:DBLOCK</span></span></dt><dd>lock handle</dd></dl></div><p>
 They contain the internal handle (a <a class="link" href="#fptr"><code class="classname">FFI:FOREIGN-POINTER</code></a>), the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>
 of parents, and the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of dependents.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="bdb-close"></a>33.7.2. Closing handles</h3></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a> will close (or commit, in the case of a
 <a class="link" href="#bdb-transaction" title="33.7.13. Transaction Subsystem">transaction</a>, or
 put, in the case of a <a class="link" href="#bdb-lock" title="33.7.8. Lock Subsystem">lock</a>)
 the Berkeley-DB handle objects.  The <a href="impnotes.html#gc" class="olink">garbage-collect</a>or will also call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a>.
 Closing an object will <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a> all its dependents and remove the object
 itself from the dependents lists of its parents (but see
 <a class="link" href="#bdb-lock" title="33.7.8. Lock Subsystem"><code class="function">BDB:LOCK-CLOSE</code></a>).</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="bdb-db-environment"></a>33.7.3. Database Environment</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">(BDB:DB-VERSION <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
    subsystems-too)</code></span></dt><dd><p>Return version information as multiple values:</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">descriptive <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>
       (from <a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/env_version.html"><code class="function">db_version</code></a>)</li><li class="listitem">major version number (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_fixnum.html" target="_top"><code class="classname">FIXNUM</code></a>)</li><li class="listitem">minor version number (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_fixnum.html" target="_top"><code class="classname">FIXNUM</code></a>)</li><li class="listitem">patch number (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_fixnum.html" target="_top"><code class="classname">FIXNUM</code></a>)</li></ol></div><p>When the optional argument is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, returns the
    <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_a.html#association_list">association list</a> of the subsystem versions as the 5th value.
 </p></dd><dt><a id="dbe-create"></a><span class="term"><code class="code">(BDB:DBE-CREATE <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    PASSWORD ENCRYPT)</code></span></dt><dd>Create an environment handle
    (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/env_class.html"><code class="function">db_env_create</code></a>),
    possibly using encryption with password
    (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_encrypt.html"><code class="function">DB_ENV-&gt;set_encrypt</code></a>).
 </dd><dt><span class="term"><code class="code">(BDB:DBE-CLOSE dbe)</code></span></dt><dd>Close an environment
    (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envclose.html"><code class="function">DB_ENV-&gt;close</code></a>).
    You can also call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a>.</dd><dt><span class="term"><code class="code">(BDB:DBE-MESSAGES dbe)</code></span></dt><dd>Return the verbose messages accumulated so far
    (requires Berkeley-DB 4.3 or better).</dd><dt><span class="term"><code class="code">(BDB:DBREMOVE dbe file
    database <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> TRANSACTION AUTO-COMMIT)</code></span></dt><dd>Remove a database
    (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envdbremove.html"><code class="function">DB_ENV-&gt;dbremove</code></a>).
 </dd><dt><span class="term"><code class="code">(BDB:DBREMOVE dbe file
    database newname <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> TRANSACTION AUTO-COMMIT)</code></span></dt><dd>Rename a database
    (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envdbrename.html"><code class="function">DB_ENV-&gt;dbrename</code></a>).
 </dd><dt><a id="dbe-open"></a><span class="term"><code class="code">(BDB:DBE-OPEN dbe <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    FLAGS HOME JOIN INIT-CDB INIT-LOCK INIT-LOG INIT-MPOOL INIT-TXN
    RECOVER RECOVER-FATAL USE-ENVIRON USE-ENVIRON-ROOT CREATE
    LOCKDOWN PRIVATE SYSTEM-MEM THREAD MODE)</code></span></dt><dd>Open an environment
    (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envopen.html"><code class="function">DB_ENV-&gt;open</code></a>).
    <code class="constant">:FLAGS</code> may be the value of a previous call
    to <code class="code">(<a class="link" href="#dbe-get-options"><code class="function">BDB:DBE-GET-OPTIONS</code></a> dbe :OPEN)</code>.
 </dd><dt><span class="term"><code class="code">(BDB:DBE-REMOVE dbe <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    HOME FORCE USE-ENVIRON USE-ENVIRON-ROOT)</code></span></dt><dd>Destroy an environment
    (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envremove.html"><code class="function">DB_ENV-&gt;remove</code></a>).
 </dd><dt><a id="with-dbe"></a><span class="term"><code class="code">(BDB:WITH-DBE (var <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    <em class="replaceable"><code>create</code></em> <em class="replaceable"><code>options</code></em>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> body)</code></span></dt><dd>Create an environment, execute <em class="replaceable"><code>body</code></em>, close it.
    <em class="replaceable"><code>create</code></em> is a list of options to be passed to <a class="link" href="#dbe-create"><code class="function">BDB:DBE-CREATE</code></a>,
    <em class="replaceable"><code>options</code></em> is a list of options to be passed to <a class="link" href="#dbe-set-options"><code class="function">BDB:DBE-SET-OPTIONS</code></a>.
 </dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="bdb-environment-config"></a>33.7.4. Environment Configuration</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><a id="dbe-set-options"></a><span class="term"><code class="code">(BDB:DBE-SET-OPTIONS dbe
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> MSGFILE ERRFILE ERRPFX PASSWORD ENCRYPT LOCK-TIMEOUT TXN-TIMEOUT
   SHM-KEY TAS-SPINS TX-TIMESTAMP TX-MAX DATA-DIR TMP-DIR
   INTERMEDIATE-DIR-MODE LG-BSIZE LG-DIR
   LG-MAX LG-REGIONMAX NCACHE CACHESIZE CACHE LK-CONFLICTS LK-DETECT
   LK-MAX-LOCKERS LK-MAX-LOCKS LK-MAX-OBJECTS
   LOG-DIRECT LOG-DSYNC LOG-AUTO-REMOVE LOG-IN-MEMORY LOG-ZERO
   AUTO-COMMIT CDB-ALLDB DIRECT-DB NOLOCKING NOMMAP NOPANIC
   OVERWRITE PANIC-ENVIRONMENT REGION-INIT TXN-NOSYNC TXN-WRITE-NOSYNC YIELDCPU
   VERB-CHKPOINT VERB-DEADLOCK VERB-RECOVERY VERB-REPLICATION VERB-WAITSFOR
   VERBOSE)</code></span></dt><dd><p>Set some environment options using </p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_flags.html"><code class="function">DB_ENV-&gt;set_flags</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_shm_key.html"><code class="function">DB_ENV-&gt;set_shm_key</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_lg_regionmax.html"><code class="function">DB_ENV-&gt;set_lg_regionmax</code></a></td></tr><tr><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envlog_set_config.html"><code class="function">DB_ENV-&gt;log_set_config</code></a> (v4.7+)</td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_timeout.html"><code class="function">DB_ENV-&gt;set_timeout</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_lk_conflicts.html"><code class="function">DB_ENV-&gt;set_lk_conflicts</code></a></td></tr><tr><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_verbose.html"><code class="function">DB_ENV-&gt;set_verbose</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_encrypt.html"><code class="function">DB_ENV-&gt;set_encrypt</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_lk_detect.html"><code class="function">DB_ENV-&gt;set_lk_detect</code></a></td></tr><tr><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_intermediate_dir_mode.html"><code class="function">DB_ENV-&gt;set_intermediate_dir_mode</code></a> (v4.7+)</td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_errfile.html"><code class="function">DB_ENV-&gt;set_errfile</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_lk_max_lockers.html"><code class="function">DB_ENV-&gt;set_lk_max_lockers</code></a></td></tr><tr><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_tmp_dir.html"><code class="function">DB_ENV-&gt;set_tmp_dir</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_msgfile.html"><code class="function">DB_ENV-&gt;set_msgfile</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_lk_max_locks.html"><code class="function">DB_ENV-&gt;set_lk_max_locks</code></a></td></tr><tr><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_data_dir.html"><code class="function">DB_ENV-&gt;set_data_dir</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_errpfx.html"><code class="function">DB_ENV-&gt;set_errpfx</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_lk_max_objects.html"><code class="function">DB_ENV-&gt;set_lk_max_objects</code></a></td></tr><tr><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_tx_max.html"><code class="function">DB_ENV-&gt;set_tx_max</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_lg_bsize.html"><code class="function">DB_ENV-&gt;set_lg_bsize</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_cachesize.html"><code class="function">DB_ENV-&gt;set_cachesize</code></a></td></tr><tr><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_tx_timestamp.html"><code class="function">DB_ENV-&gt;set_tx_timestamp</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_lg_dir.html"><code class="function">DB_ENV-&gt;set_lg_dir</code></a></td><td> </td></tr><tr><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_tas_spins.html"><code class="function">DB_ENV-&gt;set_tas_spins</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_lg_max.html"><code class="function">DB_ENV-&gt;set_lg_max</code></a></td><td> </td></tr></table></dd><dt><a id="dbe-get-options"></a><span class="term"><code class="code">(BDB:DBE-GET-OPTIONS dbe
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>what</code></em>)</code></span></dt><dd><p>Retrieve some environment options.
   </p><div class="variablelist"><p class="title"><strong>Values of <em class="replaceable"><code>what</code></em></strong></p><dl class="variablelist"><dt><span class="term">missing<br /></span><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></span></dt><dd>all options as a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>
    </dd><dt><span class="term"><code class="constant">:TX-TIMESTAMP</code></span></dt><dd>Recover to the time specified by timestamp
       rather than to the most current possible date
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_tx_timestamp.html"><code class="function">DB_ENV-&gt;get_tx_timestamp</code></a>)
    </dd><dt><span class="term"><code class="constant">:TX-MAX</code></span></dt><dd>the number of active transactions
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_tx_max.html"><code class="function">DB_ENV-&gt;set_tx_max</code></a>)
    </dd><dt><span class="term"><code class="constant">:DATA-DIR</code></span></dt><dd>list of data directories
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_data_dir.html"><code class="function">DB_ENV-&gt;get_data_dir</code></a>)
    </dd><dt><span class="term"><code class="constant">:TMP-DIR</code></span></dt><dd>temporary directory
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_tmp_dir.html"><code class="function">DB_ENV-&gt;get_tmp_dir</code></a>).
       May be <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</dd><dt><span class="term"><code class="constant">:INTERMEDIATE-DIR-MODE</code></span></dt><dd>mode for creating intermediate directories
       during recovery (v4.7+)
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_intermediate_dir_mode.html"><code class="function">DB_ENV-&gt;get_intermediate_dir_mode</code></a>).
    </dd><dt><span class="term"><code class="constant">:VERBOSE</code></span></dt><dd>the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of verbosity settings
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_verbose.html"><code class="function">DB_ENV-&gt;get_verbose</code></a>).
    </dd><dt><span class="term"><code class="constant">:AUTO-COMMIT</code><br /></span><span class="term"><code class="constant">:CDB-ALLDB</code><br /></span><span class="term"><code class="constant">:DIRECT-DB</code><br /></span><span class="term"><code class="constant">:LOG-DIRECT</code><br /></span><span class="term"><code class="constant">:LOG-DSYNC</code><br /></span><span class="term"><code class="constant">:LOG-AUTO-REMOVE</code><br /></span><span class="term"><code class="constant">:LOG-IN-MEMORY</code><br /></span><span class="term"><code class="constant">:LOG-ZERO</code><br /></span><span class="term"><code class="constant">:NOLOCKING</code><br /></span><span class="term"><code class="constant">:NOMMAP</code><br /></span><span class="term"><code class="constant">:NOPANIC</code><br /></span><span class="term"><code class="constant">:OVERWRITE</code><br /></span><span class="term"><code class="constant">:PANIC-ENVIRONMENT</code><br /></span><span class="term"><code class="constant">:REGION-INIT</code><br /></span><span class="term"><code class="constant">:TXN-NOSYNC</code><br /></span><span class="term"><code class="constant">:TXN-WRITE-NOSYNC</code><br /></span><span class="term"><code class="constant">:YIELDCPU</code><br /></span><span class="term"><code class="constant">:VERB-CHKPOINT</code><br /></span><span class="term"><code class="constant">:VERB-DEADLOCK</code><br /></span><span class="term"><code class="constant">:VERB-RECOVERY</code><br /></span><span class="term"><code class="constant">:VERB-REPLICATION</code><br /></span><span class="term"><code class="constant">:VERB-WAITSFOR</code></span></dt><dd>a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_boolean.html" target="_top"><code class="classname">BOOLEAN</code></a> indicator of whether this
       option is set or not
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_verbose.html"><code class="function">DB_ENV-&gt;get_verbose</code></a>,
       <a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_flags.html"><code class="function">DB_ENV-&gt;get_flags</code></a>, and
       <a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envlog_get_config.html"><code class="function">DB_ENV-&gt;log_get_config</code></a>).
    </dd><dt><span class="term"><code class="constant">:LG-BSIZE</code></span></dt><dd>log buffer size
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_lg_bsize.html"><code class="function">DB_ENV-&gt;get_lg_bsize</code></a>).
    </dd><dt><span class="term"><code class="constant">:LG-DIR</code></span></dt><dd>logging directory
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_lg_dir.html"><code class="function">DB_ENV-&gt;get_lg_dir</code></a>).
    </dd><dt><span class="term"><code class="constant">:LG-MAX</code></span></dt><dd>log file size
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_lg_max.html"><code class="function">DB_ENV-&gt;get_lg_max</code></a>).
    </dd><dt><span class="term"><code class="constant">:LG-REGIONMAX</code></span></dt><dd>logging region size
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_lg_regionmax.html"><code class="function">DB_ENV-&gt;get_lg_regionmax</code></a>).
    </dd><dt><span class="term"><code class="constant">:NCACHE</code><br /></span><span class="term"><code class="constant">:CACHESIZE</code><br /></span><span class="term"><code class="constant">:CACHE</code></span></dt><dd>cache parameters
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_cachesize.html"><code class="function">DB_ENV-&gt;get_cachesize</code></a>).
    </dd><dt><span class="term"><code class="constant">:LK-CONFLICTS</code></span></dt><dd>lock conflicts matrix
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_lk_conflicts.html"><code class="function">DB_ENV-&gt;get_lk_conflicts</code></a>).
    </dd><dt><span class="term"><code class="constant">:LK-DETECT</code></span></dt><dd>automatic deadlock detection
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_lk_detect.html"><code class="function">DB_ENV-&gt;get_lk_detect</code></a>).
    </dd><dt><span class="term"><code class="constant">:LK-MAX-LOCKERS</code></span></dt><dd>maximum number of lockers
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_lk_max_lockers.html"><code class="function">DB_ENV-&gt;get_lk_max_lockers</code></a>).
    </dd><dt><span class="term"><code class="constant">:LK-MAX-LOCKS</code></span></dt><dd>maximum number of locks
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_lk_max_locks.html"><code class="function">DB_ENV-&gt;get_lk_max_locks</code></a>).
    </dd><dt><span class="term"><code class="constant">:LK-MAX-OBJECTS</code></span></dt><dd>maximum number of lock objects
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_lk_max_objects.html"><code class="function">DB_ENV-&gt;get_lk_max_objects</code></a>).
    </dd><dt><span class="term"><code class="constant">:TAS-SPINS</code></span></dt><dd>the number of test-and-set spins
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_tas_spins.html"><code class="function">DB_ENV-&gt;get_tas_spins</code></a>).
    </dd><dt><span class="term"><code class="constant">:SHM-KEY</code></span></dt><dd>base segment ID for shared memory regions
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_shm_key.html"><code class="function">DB_ENV-&gt;get_shm_key</code></a>).
    </dd><dt><span class="term"><code class="constant">:LOCK-TIMEOUT</code><br /></span><span class="term"><code class="constant">:TXN-TIMEOUT</code></span></dt><dd>timeout values for locks or transactions in the
       database environment
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_timeout.html"><code class="function">DB_ENV-&gt;get_timeout</code></a>).
    </dd><dt><span class="term"><code class="constant">:ENCRYPT</code></span></dt><dd>encryption flags
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_encrypt_flags.html"><code class="function">DB_ENV-&gt;get_encrypt_flags</code></a>).
    </dd><dt><span class="term"><code class="constant">:ERRFILE</code></span></dt><dd><a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_errfile.html"><code class="function">DB_ENV-&gt;get_errfile</code></a>).
    </dd><dt><span class="term"><code class="constant">:MSGFILE</code></span></dt><dd><a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_msgfile.html"><code class="function">DB_ENV-&gt;get_msgfile</code></a>).
    </dd><dt><span class="term"><code class="constant">:ERRPFX</code></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_errpfx.html"><code class="function">DB_ENV-&gt;get_errpfx</code></a>).
    </dd><dt><span class="term"><code class="constant">:DB-GID-SIZE</code></span></dt><dd>the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_length.html" target="_top"><code class="function">LENGTH</code></a> of the globally unique
       <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8))</code></span> which must be passed to
       <a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/txnprepare.html"><code class="function">DB_TXN-&gt;prepare</code></a>.
    </dd><dt><span class="term"><code class="constant">:HOME</code></span></dt><dd>the home directory when open
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_home.html"><code class="function">DB_ENV-&gt;get_home</code></a>).
    </dd><dt><span class="term"><code class="constant">:OPEN</code></span></dt><dd>the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of flags passed to <a class="link" href="#dbe-open"><code class="function">BDB:DBE-OPEN</code></a>
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_open_flags.html"><code class="function">DB_ENV-&gt;get_open_flags</code></a>).
    </dd><dt><span class="term"><code class="constant">:CACHE</code></span></dt><dd>database cache information
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_cachesize.html"><code class="function">DB_ENV-&gt;get_cachesize</code></a>).
    </dd></dl></div></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="bdb-operations"></a>33.7.5. Database Operations</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><a id="db-create"></a><span class="term"><code class="code">(BDB:DB-CREATE dbe)</code></span></dt><dd>Create a database handle
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/db_class.html"><code class="function">db_create</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:DB-CLOSE db <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> NOSYNC)</code></span></dt><dd>Close a database
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbclose.html"><code class="function">DB-&gt;close</code></a>).
   You can also call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a>.</dd><dt><span class="term"><code class="code">(BDB:DB-DEL dbe key <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   TRANSACTION AUTO-COMMIT)</code></span></dt><dd>Delete items from a database
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbdel.html"><code class="function">DB-&gt;del</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:DB-FD db)</code></span></dt><dd>Return the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a> for the database
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbfd.html"><code class="function">DB-&gt;fd</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:DB-GET db key <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> ACTION AUTO-COMMIT
   DEGREE-2 DIRTY-READ MULTIPLE RMW TRANSACTION (ERROR <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>))</code></span></dt><dd><p>Get items from a database
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbget.html"><code class="function">DB-&gt;get</code></a>).
   If <code class="constant">:ERROR</code> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and the record is not found, no <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed,
   instead <code class="constant">:NOTFOUND</code> is returned.
   <code class="constant">:ACTION</code> should be one of
   </p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="constant">:CONSUME</code></td><td><code class="constant">:GET-BOTH</code></td></tr><tr><td><code class="constant">:CONSUME-WAIT</code></td><td><code class="constant">:SET-RECNO</code></td></tr></table><p>
</p></dd><dt><span class="term"><code class="code">(BDB:DB-PUT db key val
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> AUTO-COMMIT ACTION TRANSACTION)</code></span></dt><dd><p>Store items into a database
  (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbput.html"><code class="function">DB-&gt;put</code></a>).
  <code class="constant">:ACTION</code> should be one of
  </p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="constant">:APPEND</code></td><td><code class="constant">:NODUPDATA</code></td><td><code class="constant">:NOOVERWRITE</code></td></tr></table><p>
</p></dd><dt><span class="term"><code class="code">(BDB:DB-STAT db <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> FAST-STAT
   TRANSACTION)</code></span></dt><dd>Return database statistics
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbget_byteswapped.html"><code class="function">DB-&gt;get_byteswapped</code></a>,
   <a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbget_type.html"><code class="function">DB-&gt;get_type</code></a>,
   <a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbstat.html"><code class="function">DB-&gt;stat</code></a>).
</dd><dt><a id="db-open"></a><span class="term"><code class="code">(BDB:DB-OPEN db file <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   DATABASE TYPE MODE FLAGS CREATE DIRTY-READ EXCL NOMMAP RDONLY
   THREAD TRUNCATE AUTO-COMMIT TRANSACTION)</code></span></dt><dd><p>Open a database (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbopen.html"><code class="function">DB-&gt;open</code></a>).
   <code class="constant">:TYPE</code> should be one of
   </p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="constant">:BTREE</code></td><td><code class="constant">:RECNO</code></td></tr><tr><td><code class="constant">:HASH</code></td><td><code class="constant">:UNKNOWN</code> (default)</td></tr><tr><td><code class="constant">:QUEUE</code></td><td> </td></tr></table><p>
   <code class="constant">:FLAGS</code> may be the value of a previous call
   to <code class="code">(<a class="link" href="#db-get-options"><code class="function">BDB:DB-GET-OPTIONS</code></a> db :OPEN)</code>
</p></dd><dt><span class="term"><code class="code">(BDB:DB-SYNC db)</code></span></dt><dd>Flush a database to stable storage
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbsync.html"><code class="function">DB-&gt;sync</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:DB-TRUNCATE db <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   TRANSACTION AUTO-COMMIT)</code></span></dt><dd>Empty a database
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbtruncate.html"><code class="function">DB-&gt;truncate</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:DB-UPGRADE db file
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> DUPSORT)</code></span></dt><dd>Upgrade a database
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbupgrade.html"><code class="function">DB-&gt;upgrade</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:DB-RENAME db file database newname)</code></span></dt><dd>Rename a database
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbrename.html"><code class="function">DB-&gt;rename</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:DB-REMOVE db file database)</code></span></dt><dd>Remove a database
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbremove.html"><code class="function">DB-&gt;remove</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:DB-JOIN db cursor-sequence
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> JOIN-NOSORT)</code></span></dt><dd>Create a specialized join cursor for use in
   performing equality or natural joins on secondary indices
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbjoin.html"><code class="function">DB-&gt;join</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:DB-KEY-RANGE db key
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> TRANSACTION)</code></span></dt><dd>return an estimate of the proportion of keys that
   are less than, equal to, and greater than the specified key
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbkey_range.html"><code class="function">DB-&gt;key_range</code></a>).
   The underlying database must be of type Btree.
</dd><dt><span class="term"><code class="code">(BDB:DB-VERIFY db file <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   DATABASE SALVAGE AGGRESSIVE PRINTABLE NOORDERCHK)</code></span></dt><dd>Verify/salvage a database
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbverify.html"><code class="function">DB-&gt;verify</code></a>).
   <code class="constant">:SALVAGE</code>, if supplied, should be the output
   file name.  <code class="constant">:DATABASE</code>, if supplied,
   will force <code class="constant">DB_ORDERCHKONLY</code>.
</dd><dt><a id="with-db"></a><span class="term"><code class="code">(BDB:WITH-DB (var dbe file
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <em class="replaceable"><code>create</code></em> <em class="replaceable"><code>options</code></em> <em class="replaceable"><code>open</code></em>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> body)</code></span></dt><dd>Open the database, execute <em class="replaceable"><code>body</code></em>, close it.
   <em class="replaceable"><code>create</code></em> is a list of options to be passed to <a class="link" href="#db-create"><code class="function">BDB:DB-CREATE</code></a>,
   <em class="replaceable"><code>options</code></em> is a list of options to be passed to <a class="link" href="#db-set-options"><code class="function">BDB:DB-SET-OPTIONS</code></a>,
   <em class="replaceable"><code>open</code></em> is a list of options to be passed to <a class="link" href="#db-open"><code class="function">BDB:DB-OPEN</code></a>.
</dd><dt><a id="db-compact"></a><span class="term"><code class="code">(BDB:DB-COMPACT db <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   TRANSACTION START STOP FREE FILL TIMEOUT PAGES TYPE)</code></span></dt><dd>Call <a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbcompact.html"><code class="function">DB-&gt;compact</code></a>.
   <code class="constant">:FREE</code> is either <code class="constant">:LIST-ONLY</code>
   or <code class="constant">:SPACE</code>.
   <code class="constant">:FILL</code>, <code class="constant">:TIMEOUT</code>,
   <code class="constant">:PAGES</code> are passed in <span class="type">DB_COMPACT</span>.
   <code class="constant">:TYPE</code> is how the <code class="varname">end</code> is returned.
   The second return value is a <span class="type">BDB:DB-COMPACT</span>.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="bdb-db-config"></a>33.7.6. Database Configuration</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><a id="db-set-options"></a><span class="term"><code class="code">(BDB:DB-SET-OPTIONS db
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> ERRFILE MSGFILE ERRPFX PASSWORD ENCRYPTION NCACHE CACHESIZE CACHE
   LORDER PAGESIZE BT-MINKEY H-FFACTOR H-NELEM Q-EXTENTSIZE
   RE-DELIM RE-LEN RE-PAD RE-SOURCE
   CHKSUM ENCRYPT TXN-NOT-DURABLE DUP DUPSORT INORDER RECNUM REVSPLITOFF
   RENUMBER SNAPSHOT)</code></span></dt><dd><p>Set some database options using </p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_errfile.html"><code class="function">DB_ENV-&gt;set_errfile</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbset_pagesize.html"><code class="function">DB-&gt;set_pagesize</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbset_re_len.html"><code class="function">DB-&gt;set_re_len</code></a></td></tr><tr><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_msgfile.html"><code class="function">DB_ENV-&gt;set_msgfile</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbset_bt_minkey.html"><code class="function">DB-&gt;set_bt_minkey</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbset_re_pad.html"><code class="function">DB-&gt;set_re_pad</code></a></td></tr><tr><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envset_errpfx.html"><code class="function">DB_ENV-&gt;set_errpfx</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbset_h_ffactor.html"><code class="function">DB-&gt;set_h_ffactor</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbset_re_source.html"><code class="function">DB-&gt;set_re_source</code></a></td></tr><tr><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbset_encrypt.html"><code class="function">DB-&gt;set_encrypt</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbset_h_nelem.html"><code class="function">DB-&gt;set_h_nelem</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbset_flags.html"><code class="function">DB-&gt;set_flags</code></a></td></tr><tr><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbset_cachesize.html"><code class="function">DB-&gt;set_cachesize</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbset_q_extentsize.html"><code class="function">DB-&gt;set_q_extentsize</code></a></td><td> </td></tr><tr><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbset_lorder.html"><code class="function">DB-&gt;set_lorder</code></a></td><td><a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbset_re_delim.html"><code class="function">DB-&gt;set_re_delim</code></a></td><td> </td></tr></table></dd><dt><a id="db-get-options"></a><span class="term"><code class="code">(BDB:DB-GET-OPTIONS db
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>what</code></em>)</code></span></dt><dd><p>Retrieve some database options.
   </p><div class="variablelist"><p class="title"><strong>Values of <em class="replaceable"><code>what</code></em></strong></p><dl class="variablelist"><dt><span class="term">missing<br /></span><span class="term"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></span></dt><dd>all options as a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>
    </dd><dt><span class="term"><code class="constant">:FLAGS</code></span></dt><dd>all flags
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_flags.html"><code class="function">DB_ENV-&gt;get_flags</code></a>).
    </dd><dt><span class="term"><code class="constant">:CHKSUM</code><br /></span><span class="term"><code class="constant">:ENCRYPT</code><br /></span><span class="term"><code class="constant">:TXN-NOT-DURABLE</code><br /></span><span class="term"><code class="constant">:DUP</code><br /></span><span class="term"><code class="constant">:DUPSORT</code><br /></span><span class="term"><code class="constant">:INORDER</code><br /></span><span class="term"><code class="constant">:RECNUM</code><br /></span><span class="term"><code class="constant">:REVSPLITOFF</code><br /></span><span class="term"><code class="constant">:RENUMBER</code><br /></span><span class="term"><code class="constant">:SNAPSHOT</code></span></dt><dd>a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_boolean.html" target="_top"><code class="classname">BOOLEAN</code></a> indicator of whether this
       option is set or not
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_verbose.html"><code class="function">DB_ENV-&gt;get_verbose</code></a> and
       <a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_flags.html"><code class="function">DB_ENV-&gt;get_flags</code></a>).
    </dd><dt><span class="term"><code class="constant">:CACHE</code></span></dt><dd>database cache information
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbget_cachesize.html"><code class="function">DB-&gt;get_cachesize</code></a> or
       <a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_cachesize.html"><code class="function">DB_ENV-&gt;get_cachesize</code></a> if the
       database was created within an environment).
    </dd><dt><span class="term"><code class="constant">:ENCRYPTION</code></span></dt><dd>encryption flags
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_encrypt_flags.html"><code class="function">DB_ENV-&gt;get_encrypt_flags</code></a>).
    </dd><dt><span class="term"><code class="constant">:ERRFILE</code></span></dt><dd><a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_errfile.html"><code class="function">DB_ENV-&gt;get_errfile</code></a>).
    </dd><dt><span class="term"><code class="constant">:MSGFILE</code></span></dt><dd><a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_msgfile.html"><code class="function">DB_ENV-&gt;get_msgfile</code></a>).
    </dd><dt><span class="term"><code class="constant">:ERRPFX</code></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envget_errpfx.html"><code class="function">DB_ENV-&gt;get_errpfx</code></a>).
    </dd><dt><span class="term"><code class="constant">:PAGESIZE</code></span></dt><dd>database page size
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbget_pagesize.html"><code class="function">DB-&gt;get_pagesize</code></a>).
    </dd><dt><span class="term"><code class="constant">:BT-MINKEY</code></span></dt><dd>the minimum number of key/data pairs intended to
       be stored on any single <code class="constant">:BTREE</code> leaf page
       underlying source file
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbget_bt_minkey.html"><code class="function">DB-&gt;get_bt_minkey</code></a>).
    </dd><dt><span class="term"><code class="constant">:H-FFACTOR</code></span></dt><dd>the desired density within
       the <code class="constant">:HASH</code> table
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbget_h_ffactor.html"><code class="function">DB-&gt;get_h_ffactor</code></a>).
    </dd><dt><span class="term"><code class="constant">:H-NELEM</code></span></dt><dd>an estimate of the final size of
       the <code class="constant">:HASH</code> table
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbget_h_nelem.html"><code class="function">DB-&gt;get_h_nelem</code></a>).
    </dd><dt><span class="term"><code class="constant">:Q-EXTENTSIZE</code></span></dt><dd>the size of the extents used to hold pages in
       a <code class="constant">:QUEUE</code> database
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbget_q_extentsize.html"><code class="function">DB-&gt;get_q_extentsize</code></a>).
    </dd><dt><span class="term"><code class="constant">:RE-DELIM</code></span></dt><dd>the record delimiter for <code class="constant">:RECNO</code> databases
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbget_re_delim.html"><code class="function">DB-&gt;get_re_delim</code></a>).
    </dd><dt><span class="term"><code class="constant">:RE-LEN</code></span></dt><dd>database record length
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbget_re_len.html"><code class="function">DB-&gt;get_re_len</code></a>).
    </dd><dt><span class="term"><code class="constant">:RE-PAD</code></span></dt><dd>database record pad byte
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbget_re_pad.html"><code class="function">DB-&gt;get_re_pad</code></a>).
    </dd><dt><span class="term"><code class="constant">:RE-SOURCE</code></span></dt><dd>the underlying source file for <code class="constant">:RECNO</code> databases
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbget_re_source.html"><code class="function">DB-&gt;get_re_source</code></a>).
    </dd><dt><span class="term"><code class="constant">:LORDER</code></span></dt><dd>database byte order
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbget_lorder.html"><code class="function">DB-&gt;get_lorder</code></a>).
    </dd><dt><span class="term"><code class="constant">:DBNAME</code></span></dt><dd>the file name and database name
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbget_dbname.html"><code class="function">DB-&gt;get_dbname</code></a>)
    </dd><dt><span class="term"><code class="constant">:TRANSACTIONAL</code></span></dt><dd>the indicator whether the database is transactional
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbget_transactional.html"><code class="function">DB-&gt;get_transactional</code></a>).
    </dd><dt><span class="term"><code class="constant">:OPEN</code></span></dt><dd>the flags passed to <a class="link" href="#db-open"><code class="function">BDB:DB-OPEN</code></a>
       (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbget_open_flags.html"><code class="function">DB-&gt;get_open_flags</code></a>).
    </dd></dl></div><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>Once you call a method for one type of access method,
    the handle can only be used for that type.
    The methods <a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbget_re_delim.html"><code class="function">DB-&gt;get_re_delim</code></a>
    and <a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbget_re_source.html"><code class="function">DB-&gt;get_re_source</code></a> are for
    a <code class="constant">:RECNO</code> database so you <span class="strong"><strong>cannot</strong></span> call them
    (by passing <code class="constant">:RE-DELIM</code>
    or <code class="constant">:RE-SOURCE</code> to this function)
    and then use the database handle to open a database of different type
    (e.g., <code class="constant">:QUEUE</code>).</p></div></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="bdb-cursor"></a>33.7.7. Database Cursor Operations</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><a id="make-dbc"></a><span class="term"><code class="code">(BDB:MAKE-DBC db <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   DEGREE-2 DIRTY-READ WRITECURSOR TRANSACTION)</code></span></dt><dd>Create a cursor handle
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbcursor.html"><code class="function">DB-&gt;cursor</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:DBC-CLOSE cursor)</code></span></dt><dd>Close the cursor handle
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbcclose.html"><code class="function">DBCursor-&gt;close</code></a>).
   You can also call <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a>.</dd><dt><span class="term"><code class="code">(BDB:DBC-COUNT cursor)</code></span></dt><dd>Return count of duplicates
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbccount.html"><code class="function">DBCursor-&gt;count</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:DBC-DEL cursor <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> CONSUME)</code></span></dt><dd>Delete by cursor
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbcdel.html"><code class="function">DBCursor-&gt;del</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:DBC-DUP cursor <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> POSITION)</code></span></dt><dd>Duplicate a cursor
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbcdup.html"><code class="function">DBCursor-&gt;dup</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:DBC-GET cursor key data action
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> DEGREE-2 DIRTY-READ MULTIPLE (ERROR <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>))</code></span></dt><dd><p>Retrieve by cursor
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbcget.html"><code class="function">DBCursor-&gt;get</code></a>).
   If <code class="constant">:ERROR</code> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and the record is not found, no <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed,
   <code class="constant">:NOTFOUND</code> or <code class="constant">:KEYEMPTY</code>
   is returned instead, as appropriate.
   <em class="replaceable"><code>action</code></em> should be one of
   </p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="constant">:CURRENT</code></td><td><code class="constant">:GET-RECNO</code></td><td><code class="constant">:NEXT-DUP</code></td><td><code class="constant">:SET</code></td></tr><tr><td><code class="constant">:FIRST</code></td><td><code class="constant">:JOIN-ITEM</code></td><td><code class="constant">:NEXT-NODUP</code></td><td><code class="constant">:SET-RANGE</code></td></tr><tr><td><code class="constant">:GET-BOTH</code></td><td><code class="constant">:LAST</code></td><td><code class="constant">:PREV</code></td><td><code class="constant">:SET-RECNO</code></td></tr><tr><td><code class="constant">:GET-BOTH-RANGE</code></td><td><code class="constant">:NEXT</code></td><td><code class="constant">:PREV-NODUP</code></td><td> </td></tr></table><p>
</p></dd><dt><span class="term"><code class="code">(BDB:DBC-PUT cursor key data flag)</code></span></dt><dd>Store by cursor
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/dbcput.html"><code class="function">DBCursor-&gt;put</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:WITH-DBC (var <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a>
   <em class="replaceable"><code>options</code></em>) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> <em class="replaceable"><code>body</code></em>))</code></span></dt><dd>Open a cursor, execute <em class="replaceable"><code>body</code></em>, close it.
   <em class="replaceable"><code>options</code></em> are passed to <a class="link" href="#make-dbc"><code class="function">BDB:MAKE-DBC</code></a>.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="bdb-lock"></a>33.7.8. Lock Subsystem</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">(BDB:LOCK-DETECT dbe action)</code></span></dt><dd>Perform deadlock detection
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envlock_detect.html"><code class="function">DB_ENV-&gt;lock_detect</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:LOCK-ID dbe)</code></span></dt><dd>Acquire a locker ID
  (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envlock_id.html"><code class="function">DB_ENV-&gt;lock_id</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:LOCK-ID-FREE dbe id)</code></span></dt><dd>Release a locker ID
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envlock_id_free.html"><code class="function">DB_ENV-&gt;lock_id_free</code></a>).
   All associated locks should be released first.
</dd><dt><span class="term"><code class="code">(BDB:LOCK-GET dbe object locker
   mode <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> NOWAIT)</code></span></dt><dd>Acquire a lock
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envlock_get.html"><code class="function">DB_ENV-&gt;lock_get</code></a>).
   The <span class="type">BDB:DBLOCK</span> object returned by this function will
   <span class="strong"><strong>not</strong></span> be released when the environment is closed.
   This permits long-lived locks.</dd><dt><span class="term"><code class="code">(BDB:LOCK-PUT dbe lock)</code></span></dt><dd>Release a lock
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envlock_put.html"><code class="function">DB_ENV-&gt;lock_put</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:LOCK-CLOSE lock)</code></span></dt><dd><p class="simpara">Release a lock
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envlock_put.html"><code class="function">DB_ENV-&gt;lock_put</code></a>) using the
   environment with which it has been acquired.
   This is used to <a class="link" href="#final" title="31.8. Finalization"><code class="function">EXT:FINALIZE</code></a> <span class="type">BDB:DBLOCK</span> objects.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>If that environment has already been closed, you are
    in a big trouble (segfault), so you better release your locks or do
    not drop them.</p></div></dd><dt><span class="term"><code class="code">(BDB:LOCK-STAT dbe <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   STAT-CLEAR)</code></span></dt><dd>Return lock subsystem statistics
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envlock_stat.html"><code class="function">DB_ENV-&gt;lock_stat</code></a>).
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="bdb-log"></a>33.7.9. Log Subsystem</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#bdb-log-cursor">33.7.9.1. Log Cursor Operations</a></span></dt><dt><span class="section"><a href="#bdb-log-seq">33.7.9.2. Log Sequence Numbers</a></span></dt></dl></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">(BDB:LOG-ARCHIVE dbe
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> ARCH-ABS ARCH-DATA ARCH-LOG ARCH-REMOVE)</code></span></dt><dd>Return a list of log or database filenames
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envlog_archive.html"><code class="function">DB_ENV-&gt;log_archive</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:LOG-FILE dbe lsn)</code></span></dt><dd>Return the name of the file containing the record
   named by <em class="replaceable"><code>lsn</code></em>
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envlog_file.html"><code class="function">DB_ENV-&gt;log_file</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:LOG-FLUSH dbe lsn)</code></span></dt><dd>Flush log records to disk
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envlog_flush.html"><code class="function">DB_ENV-&gt;log_flush</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:LOG-PUT dbe data
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :FLUSH)</code></span></dt><dd>Write a log record
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envlog_put.html"><code class="function">DB_ENV-&gt;log_put</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:LOG-STAT dbe
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> STAT-CLEAR)</code></span></dt><dd>Logging subsystem statistics
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envlog_stat.html"><code class="function">DB_ENV-&gt;log_stat</code></a>).
</dd></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="bdb-log-cursor"></a>33.7.9.1. Log Cursor Operations</h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">(BDB:LOG-CURSOR dbe)</code></span></dt><dd>Create a log cursor handle
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envlog_cursor.html"><code class="function">DB_ENV-&gt;log_cursor</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:LOGC-CLOSE logc)</code></span></dt><dd>Close a log cursor handle
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/logcclose.html"><code class="function">DB_LOGC-&gt;close</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:LOGC-GET logc action
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> TYPE ERROR)</code></span></dt><dd><p>Retrieve a log record
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/logcget.html"><code class="function">DB_LOGC-&gt;get</code></a>).
   If <code class="constant">:ERROR</code> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and the record is not found, no <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed,
   <code class="constant">:NOTFOUND</code> is returned instead.
   </p><div class="variablelist"><p class="title"><strong>Valid <em class="replaceable"><code>action</code></em>s</strong></p><dl class="variablelist"><dt><span class="term"><code class="constant">:CURRENT</code><br /></span><span class="term"><code class="constant">:FIRST</code><br /></span><span class="term"><code class="constant">:LAST</code><br /></span><span class="term"><code class="constant">:NEXT</code><br /></span><span class="term"><code class="constant">:PREV</code></span></dt><dd>Retrieve the appropriate record.
    </dd><dt><span class="term"><span class="type">DB:LSN</span></span></dt><dd>Retrieve the specified record, as
       with <code class="constant">DB_SET</code>.
   </dd></dl></div><p>
   Returns two values: the datum of type specified by the <code class="constant">:TYPE</code>
   argument and the <span class="type">DB:LSN</span> value of the record retrieved
   (when <em class="replaceable"><code>action</code></em> is a <span class="type">DB:LSN</span>, it
   is returned unchanged).
</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="bdb-log-seq"></a>33.7.9.2. Log Sequence Numbers</h4></div></div></div><p>Use <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_equalp.html" target="_top"><code class="function">EQUALP</code></a> to check similarity of <span class="type">BDB:LSN</span> objects.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">(BDB:LOG-COMPARE lsn1 lsn2)</code></span></dt><dd>Compare two Log Sequence Numbers
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/log_compare.html"><code class="function">log_compare</code></a>).
</dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="bdb-mem-pool"></a>33.7.10. Memory Pool Subsystem</h3></div></div></div><p>not implemented yet, patches are welcome</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="bdb-replication"></a>33.7.11. Replication</h3></div></div></div><p>not implemented yet, patches are welcome</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="bdb-sequences"></a>33.7.12. Sequences</h3></div></div></div><p>not implemented yet, patches are welcome</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="bdb-transaction"></a>33.7.13. Transaction Subsystem</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">(BDB:TXN-BEGIN dbe <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   DEGREE-2 PARENT DIRTY-READ NOSYNC NOWAIT SYNC)</code></span></dt><dd>Begin a transaction
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envtxn_begin.html"><code class="function">DB_ENV-&gt;txn_begin</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:TXN-ABORT txn)</code></span></dt><dd>Abort a transaction
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/txnabort.html"><code class="function">DB_TXN-&gt;abort</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:TXN-COMMIT txn <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   NOSYNC SYNC)</code></span></dt><dd>Commit a transaction
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/txncommit.html"><code class="function">DB_TXN-&gt;commit</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:TXN-DISCARD txn)</code></span></dt><dd>Discard a transaction
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/txndiscard.html"><code class="function">DB_TXN-&gt;discard</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:TXN-ID txn)</code></span></dt><dd>Return the transaction's ID
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/txnid.html"><code class="function">DB_TXN-&gt;id</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:TXN-CHECKPOINT dbe
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> KBYTE MIN FORCE)</code></span></dt><dd>Checkpoint the transaction subsystem
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envtxn_checkpoint.html"><code class="function">DB_ENV-&gt;txn_checkpoint</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:TXN-PREPARE txn id)</code></span></dt><dd>Initiate the beginning of a two-phase commit
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/txnprepare.html"><code class="function">DB_TXN-&gt;prepare</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:TXN-RECOVER dbe <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   FIRST NEXT)</code></span></dt><dd>Return a list of prepared but not yet resolved
   transactions (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envtxn_recover.html"><code class="function">DB_ENV-&gt;txn_recover</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:TXN-SET-TIMEOUT txn
   timeout which)</code></span></dt><dd>Set timeout values for locks or transactions for the
   specified transaction
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/txnset_timeout.html"><code class="function">DB_TXN-&gt;set_timeout</code></a>).
</dd><dt><span class="term"><code class="code">(BDB:TXN-STAT dbe <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   STAT-CLEAR)</code></span></dt><dd>Transaction subsystem statistics
   (<a class="bdb" href="http://docs.oracle.com/cd/E17076_02/html/api_reference/C/envtxn_stat.html"><code class="function">DB_ENV-&gt;txn_stat</code></a>).
</dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="dir-key"></a>33.8. Directory Access</h2></div></div></div><p>This module provides some directory access from lisp,
 in package <a class="link" href="#dir-key" title="33.8. Directory Access"><strong class="package"><span class="quote">“<span class="quote">LDAP</span>”</span></strong></a>.</p><p>When this module is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a>
 contains the symbol <code class="constant">:DIRKEY</code>.</p><p>3 types of directory keys may exist,
 depending on the compilation environment.</p><div class="variablelist"><a id="dir-key-type"></a><p class="title"><strong>valid directory key types</strong></p><dl class="variablelist"><dt><span class="term">:win32</span></dt><dd><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> registry access
  </dd><dt><span class="term">:gnome</span></dt><dd><a class="ulink" href="http://library.gnome.org/devel/libgnome/stable/libgnome-gnome-config.html" target="_top">gnome-config</a> access
  </dd><dt><span class="term">:ldap</span></dt><dd>LDAP interface via
   <a class="ulink" href="http://www.openldap.org" target="_top">OpenLDAP</a> or compatible
  </dd></dl></div><p>The following functions and macros are exported (please note that
these features are <span class="strong"><strong><a class="ulink" href="http://www.cygwin.com/acronyms/#PTC" target="_top">experimental</a></strong></span> and the API may be modified in the
future).</p><div class="variablelist"><dl class="variablelist"><dt><a id="dir-key-open"></a><span class="term"><code class="code">(<a class="link" href="#dir-key-open"><code class="function">LDAP:DIR-KEY-OPEN</code></a>
   <em class="replaceable"><code>dkey</code></em> <em class="replaceable"><code>pathname</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> (<code class="constant">:DIRECTION</code> <code class="constant">:INPUT</code>)
   <code class="constant">:IF-DOES-NOT-EXIST</code>)</code></span></dt><dd>Open the directory key under <em class="replaceable"><code>dkey</code></em>, which should
   be either an open directory key or a valid <a class="link" href="#dir-key-type" title="valid directory key types">directory key type</a>.
   The meaning of the <code class="constant">:DIRECTION</code> and <code class="constant">:IF-DOES-NOT-EXIST</code> keyword
   arguments is the same as for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_open.html" target="_top"><code class="function">OPEN</code></a>.</dd><dt><a id="dir-key-close"></a><span class="term"><code class="code">(<a class="link" href="#dir-key-close"><code class="function">LDAP:DIR-KEY-CLOSE</code></a>
    <em class="replaceable"><code>dkey</code></em>)</code></span></dt><dd>Close the directory key.  The preferred way is to
   use the <a class="link" href="#with-dir-key-open"><code class="function">LDAP:WITH-DIR-KEY-OPEN</code></a> macro.</dd><dt><a id="with-dir-key-open"></a><span class="term"><code class="code">(<a class="link" href="#with-dir-key-open"><code class="function">LDAP:WITH-DIR-KEY-OPEN</code></a> (<em class="replaceable"><code>variable</code></em>
    <em class="replaceable"><code>dkey</code></em> <em class="replaceable"><code>pathname</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> {<em class="replaceable"><code>option</code></em>}*) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a>
    <em class="replaceable"><code>body</code></em>)</code></span></dt><dd>Open the directory key (by calling <a class="link" href="#dir-key-open"><code class="function">LDAP:DIR-KEY-OPEN</code></a>
   on <em class="replaceable"><code>dkey</code></em>, <em class="replaceable"><code>pathname</code></em> and <em class="replaceable"><code>option</code></em>s), bind it to <em class="replaceable"><code>variable</code></em>,
   execute <em class="replaceable"><code>body</code></em>, then close it with <a class="link" href="#dir-key-close"><code class="function">LDAP:DIR-KEY-CLOSE</code></a>.
 </dd><dt><span class="term"><code class="code">(<code class="function">LDAP:DIR-KEY-TYPE</code>
    <em class="replaceable"><code>dkey</code></em>)</code></span></dt><dd>Return the <a class="link" href="#dir-key-type" title="valid directory key types">directory key type</a> of the directory key
  </dd><dt><span class="term"><code class="code">(<code class="function">LDAP:DIR-KEY-PATH</code>
                <em class="replaceable"><code>dkey</code></em>)</code></span></dt><dd>Return the path of this directory key, which is the
   <em class="replaceable"><code>pathname</code></em> argument of <a class="link" href="#dir-key-open"><code class="function">LDAP:DIR-KEY-OPEN</code></a> if <em class="replaceable"><code>dkey</code></em> was a <a class="link" href="#dir-key-type" title="valid directory key types">directory key type</a> or the
   concatenation of the <em class="replaceable"><code>pathname</code></em> argument and the
   <code class="function">ldap:dir-key-path</code> of <em class="replaceable"><code>dkey</code></em>.
   </dd><dt><span class="term"><code class="code">(<code class="function">LDAP:DIR-KEY-DIRECTION</code>
    <em class="replaceable"><code>dkey</code></em>)</code></span></dt><dd>One of <code class="constant">:INPUT</code>, <code class="constant">:OUTPUT</code> and <code class="constant">:IO</code>, indicating
   the permitted operation on this key and its derivatives.
   </dd><dt><span class="term"><code class="code">(<code class="function">LDAP:DIR-KEY-CLOSED-P</code>
    <em class="replaceable"><code>dkey</code></em>)</code></span></dt><dd>Check whether the key has been closed.
   It is not an error to close a closed key.
   </dd><dt><span class="term"><code class="code">(<code class="function">LDAP:DIR-KEY-SUBKEY-DELETE</code>
     <em class="replaceable"><code>dkey</code></em> <em class="replaceable"><code>subkey</code></em>)</code>
   <code class="code">(<code class="function">LDAP:DIR-KEY-VALUE-DELETE</code>
     <em class="replaceable"><code>dkey</code></em> <em class="replaceable"><code>attribute</code></em>)</code></span></dt><dd>Delete the specified subkey or attribute.
  </dd><dt><span class="term"><code class="code">(<code class="function">LDAP:DIR-KEY-SUBKEY</code>
    <em class="replaceable"><code>dkey</code></em>)</code>
  <code class="code">(<code class="function">LDAP:DIR-KEY-ATTRIBUTES</code> <em class="replaceable"><code>dkey</code></em>)</code></span></dt><dd>Return the list of the subkeys or attributes.
  </dd><dt><span class="term"><code class="code">(<code class="function">LDAP:DIR-KEY-VALUE</code> <em class="replaceable"><code>dkey</code></em>
    <em class="replaceable"><code>attribute</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
    <em class="replaceable"><code>default</code></em>)</code></span></dt><dd>Return the value of the specified attribute,
   similar to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_gethash.html" target="_top"><code class="function">GETHASH</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>able just like <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_gethash.html" target="_top"><code class="function">GETHASH</code></a>.
   </dd><dt><span class="term"><code class="code">(<code class="function">LDAP:DIR-KEY-INFO</code>
    <em class="replaceable"><code>dkey</code></em>)</code></span></dt><dd>Return some information about the directory key.
   This is highly platform-dependent and will probably be removed or
   replaced or modified in the future.</dd><dt><a id="with-dir-key-search"></a><span class="term"><code class="code">(<a class="link" href="#with-dir-key-search"><code class="function">LDAP:WITH-DIR-KEY-SEARCH</code></a>
    (<em class="replaceable"><code>key-iter</code></em>
    <em class="replaceable"><code>atribute-iter</code></em>
    <em class="replaceable"><code>dkey</code></em> <em class="replaceable"><code>pathname</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <code class="constant">:scope</code>)
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> <em class="replaceable"><code>body</code></em>)</code></span></dt><dd><p class="simpara">This is the main way to iterate over the subtree
   under the key <em class="replaceable"><code>dkey</code></em>+<em class="replaceable"><code>pathname</code></em>.</p><p class="simpara"><em class="replaceable"><code>key-iter</code></em> is a non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> symbol
    and is bound via <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_fletcm_scm_macrolet.html" target="_top"><code class="function">MACROLET</code></a> to a macro, each call of which returns
    the next subkey.</p><p class="simpara"><em class="replaceable"><code>atribute-iter</code></em> is a symbol and is
    bound, when non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, to a macro, each call of which returns two
   values - the next attribute and its value.</p><p>The <code class="constant">:scope</code> keyword argument specifies the
    scope of the search and can be
   </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="constant">:self</code></span></dt><dd>iterate over the key itself
     </dd><dt><span class="term"><code class="constant">:level</code></span></dt><dd>iterate over the children of the key
     </dd><dt><span class="term"><code class="constant">:tree</code></span></dt><dd>iterate over the subtree
     </dd></dl></div><p class="simpara"><a class="link" href="#with-dir-key-search"><code class="function">LDAP:WITH-DIR-KEY-SEARCH</code></a> is used to implement
    <code class="function">LDAP:DIR-KEY-VALUES</code>,
    <code class="function">LDAP:DIR-KEY-CHILDREN</code> and
    <code class="function">LDAP:DIR-KEY-DUMP-TREE</code> in
    <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/dirkey/dirkey1.lisp"><code class="filename">modules/dirkey/dirkey1.lisp</code></a>.
    </p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="postgresql"></a>33.9. PostgreSQL Database Access</h2></div></div></div><p>This package offers an <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>-based interface to
 <a class="ulink" href="http://www.PostgreSQL.org/" target="_top">PostgreSQL</a>.</p><p>The package <strong class="package"><span class="quote">“<span class="quote">SQL</span>”</span></strong>
 (nicknamed <strong class="package"><span class="quote">“<span class="quote">POSTGRES</span>”</span></strong>
 and <strong class="package"><span class="quote">“<span class="quote">POSTGRESQL</span>”</span></strong>) is <a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-SENSITIVE</code></a>,
 so you would write <code class="code">(sql:PQconnectdb ...)</code>
 when you need to call <a class="pq" href="http://www.postgresql.org/search/?q=PQconnectdb"><code class="function">PQconnectdb</code></a>.</p><p>When this module is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a>
 contains the symbol <code class="constant">:POSTGRESQL</code>.</p><p>See <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/postgresql/test.tst"><code class="filename">modules/postgresql/test.tst</code></a>
 for sample usage.</p><p>Additionally, some higher level functionality is available (defined
 in <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/postgresql/sql.lisp"><code class="filename">modules/postgresql/sql.lisp</code></a>):</p><div class="variablelist"><dl class="variablelist"><dt><a id="sql:pq-finish"></a><span class="term"><code class="code">(sql:pq-finish
   <em class="replaceable"><code>connection</code></em>)</code></span></dt><dd><a class="pq" href="http://www.postgresql.org/search/?q=PQfinish"><code class="function">PQfinish</code></a> the <em class="replaceable"><code>connection</code></em>
   and mark it as invalid</dd><dt><a id="sql:pq-clear"></a><span class="term"><code class="code">(sql:pq-clear
   <em class="replaceable"><code>result</code></em>)</code></span></dt><dd><a class="pq" href="http://www.postgresql.org/search/?q=PQclear"><code class="function">PQclear</code></a> the <em class="replaceable"><code>result</code></em>
   and mark it as invalid</dd><dt><span class="term"><code class="code">(sql:sql-error <em class="replaceable"><code>connection</code></em> <em class="replaceable"><code>result</code></em> <em class="replaceable"><code>format-string</code></em>
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>arguments</code></em>)</code></span></dt><dd>finalize <em class="replaceable"><code>connection</code></em> and <em class="replaceable"><code>result</code></em> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a> an
   appropriate <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a></dd><dt><a id="sql:sql-connect"></a><span class="term"><code class="code">(sql:sql-connect
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> host port options tty name login password)</code></span></dt><dd>call <a class="pq" href="http://www.postgresql.org/search/?q=PQsetdbLogin"><code class="function">PQsetdbLogin</code></a> and
   return the <em class="replaceable"><code>connection</code></em></dd><dt><a id="sql:with-sql-connection"></a><span class="term"><code class="code">(sql:with-sql-connection
   (<em class="replaceable"><code>variable</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>option</code></em>s <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <em class="replaceable"><code>log</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;ALLOW-OTHER-KEYS</code></a>)
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> <em class="replaceable"><code>body</code></em>)</code></span></dt><dd><div class="procedure"><ol class="procedure" type="1"><li class="step"><p>bind <code class="varname">*sql-log*</code>
     to the <em class="replaceable"><code>log</code></em> argument</p></li><li class="step"><p>call <code class="function">sql:sql-connect</code> on
     <em class="replaceable"><code>option</code></em>s and bind <em class="replaceable"><code>variable</code></em> to the result</p></li><li class="step"><p>execute <em class="replaceable"><code>body</code></em></p></li><li class="step"><p>call <code class="function">sql:pq-finish</code> on
     <em class="replaceable"><code>variable</code></em></p></li></ol></div></dd><dt><span class="term"><code class="code">(sql:sql-transaction <em class="replaceable"><code>connection</code></em> <em class="replaceable"><code>command</code></em>
   <em class="replaceable"><code>status</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> (clear-p <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>))</code></span></dt><dd>execute the <em class="replaceable"><code>command</code></em> via <em class="replaceable"><code>connection</code></em>;
   if the status does not match <em class="replaceable"><code>status</code></em>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed;
   if <em class="replaceable"><code>clear-p</code></em> is
   non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> <code class="function">sql:pq-clear</code> the <em class="replaceable"><code>result</code></em>;
   otherwise return it</dd><dt><span class="term"><code class="code">(sql:with-sql-transaction (<em class="replaceable"><code>result</code></em> <em class="replaceable"><code>connection</code></em>
   <em class="replaceable"><code>command</code></em> status) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> <em class="replaceable"><code>body</code></em>)</code></span></dt><dd>execure the <em class="replaceable"><code>body</code></em> on the <em class="replaceable"><code>result</code></em> of <em class="replaceable"><code>command</code></em>,
   then <code class="function">sql:pq-clear</code> the <em class="replaceable"><code>result</code></em>
</dd><dt><a id="sql:sql-login"></a><span class="term"><code class="code">sql:*sql-login*</code></span></dt><dd>the default <em class="replaceable"><code>login</code></em>
   argument to <code class="function">sql:sql-connect</code>
   (initially set to <span class="data"><code class="literal">"postgres"</code></span>)
</dd><dt><a id="sql:sql-password"></a><span class="term"><code class="code">sql:*sql-password*</code></span></dt><dd>the default <em class="replaceable"><code>password</code></em>
   argument to <code class="function">sql:sql-connect</code>
   (initially set to <span class="data"><code class="literal">"postgres"</code></span>)
</dd><dt><a id="sql:sql-log"></a><span class="term"><code class="code">sql:*sql-log*</code></span></dt><dd>when non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, should be a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>;
   <code class="function">sql:sql-connect</code>
   and <code class="function">sql:sql-transaction</code>
   will write to it (initially set to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>)
</dd></dl></div><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>Since <a class="pq" href="http://www.postgresql.org/search/?q=PQfinish"><code class="function">PQfinish</code></a>
  and <a class="pq" href="http://www.postgresql.org/search/?q=PQclear"><code class="function">PQclear</code></a>
  cannot be called on the same pointer twice, one needs to track their
  validity (<code class="function">sql:sql-connect</code>
  and <code class="function">sql:sql-transaction</code> take care of that).
  See <a class="xref" href="#ex-dffi-validity" title="Example 32.11. Controlling validity of resources">Example 32.11, “Controlling validity of resources”</a>.</p></div><p>For <a class="pq" href="http://www.postgresql.org/search/?q=PQtrace"><code class="function">PQtrace</code></a>, see
 <a class="xref" href="#stdio" title="33.2.14. Standard file input and output">Section 33.2.14, “Standard file input and output”</a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="oracle"></a>33.10. <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> Interface</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#ora-functionality">33.10.1. Functions and Macros in   package <strong class="package"><span class="quote">“<span class="quote">ORACLE</span>”</span></strong></a></span></dt><dt><span class="section"><a href="#ora-example">33.10.2. Oracle Example</a></span></dt><dt><span class="section"><a href="#ora-config">33.10.3. Oracle Configuration</a></span></dt><dt><span class="section"><a href="#ora-build">33.10.4. Building the Oracle Interface</a></span></dt></dl></div><p>
The <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> module allows a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> program to act as client to an
<a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> database server.  The module includes full
SQL support, transactions (including auto-commit), support for most
<a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> data types (<span class="type">LONG</span>, <span class="type">BLOB</span>,
<span class="type">CLOB</span>, <span class="type">RAW</span>, etc.), automatic conversion
between <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> and <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> data types, database connection caching and
retry, concurrent connections to multiple databases, proper handling
of <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> errors, and more.</p><p>The module can be used to build sophisticated <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> database
applications in <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a>.</p><p>When this module is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a> contains the
 symbol <code class="constant">:ORACLE</code>.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="ora-functionality"></a>33.10.1. Functions and Macros in
  package <strong class="package"><span class="quote">“<span class="quote">ORACLE</span>”</span></strong></h3></div></div></div><p>Access to <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> is via these functions and macros in
package <strong class="package"><span class="quote">“<span class="quote">ORACLE</span>”</span></strong>.
When any <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> function fails, the general Lisp function
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_error.html" target="_top"><code class="function">ERROR</code></a> is called, with the condition string set to
include the <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> error number, the <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> message text,
and other context of the error (e.g., the text and parse location of a
SQL query).</p><div class="variablelist"><dl class="variablelist"><dt><a id="ora-connect"></a><span class="term"><code class="code">(ORACLE:CONNECT
<em class="replaceable"><code>user</code></em> <em class="replaceable"><code>password</code></em>
<em class="replaceable"><code>server</code></em>
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
<em class="replaceable"><code>schema</code></em>
<em class="replaceable"><code>auto-commit</code></em>
<em class="replaceable"><code>prefetch-buffer-bytes</code></em>
<em class="replaceable"><code>long-len</code></em>
<em class="replaceable"><code>truncate-ok</code></em>)</code></span></dt><dd><p class="simpara">

Connect to an <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> database.  All subsequent operations will affect
this database until the next call to <a class="link" href="#ora-connect"><code class="function">ORACLE:CONNECT</code></a>.  A
single program can access different <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> schemas concurrently by
repeated calls to <a class="link" href="#ora-connect"><code class="function">ORACLE:CONNECT</code></a>.  Database connections
are cached and re-used: if you call <a class="link" href="#ora-connect"><code class="function">ORACLE:CONNECT</code></a> again
with the same <em class="replaceable"><code>user</code></em>,
<em class="replaceable"><code>schema</code></em>, and
<em class="replaceable"><code>server</code></em>, the previous <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> connection will
be re-used.  <a class="link" href="#ora-connect"><code class="function">ORACLE:CONNECT</code></a> may not be called inside
<code class="function">WITH-TRANSACTION</code>.

Returns: <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> if a cached connection was re-used, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if a new
connection was created (and cached).

The meaning of the arguments is as follows:
</p><div class="variablelist"><p class="title"><strong>Arguments for <a class="link" href="#ora-connect"><code class="function">ORACLE:CONNECT</code></a></strong></p><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>user</code></em></span></dt><dd><a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> user ID</dd><dt><span class="term"><em class="replaceable"><code>password</code></em></span></dt><dd>Password for user, or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if
   <em class="replaceable"><code>user</code></em> has no password (!).
</dd><dt><span class="term"><em class="replaceable"><code>server</code></em></span></dt><dd><a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> server ID (SID).
</dd><dt><span class="term"><em class="replaceable"><code>schema</code></em></span></dt><dd><a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> default schema (default: <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>).
   If <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, same as user.  This allows you to log on with one user's
   id/password but see the database as if you were some other user.
</dd><dt><span class="term"><em class="replaceable"><code>auto-commit</code></em></span></dt><dd>Flag: whether to commit after every operation
   (default: <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>). Set this to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if you intend to do transactions
   and call <code class="function">COMMIT</code> explicitly.  However,
   <code class="function">WITH-TRANSACTION</code> is probably easier.
</dd><dt><span class="term"><em class="replaceable"><code>prefetch-buffer-bytes</code></em></span></dt><dd>Number of bytes to cache from SQL SELECT fetches
   (default: 64 Kbytes) If you are very short of memory, or have a slow
   connection to <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a>, you can reduce this to 10k or so.
   Alternatively, if you have a fast connection to <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> and
   regularly do large queries, you can increase throughput by increasing
   this value.</dd><dt><span class="term"><em class="replaceable"><code>long-len</code></em></span></dt><dd>Number of bytes to fetch for "long" (LONG, [BC]LOB)
   types.  Long data that exceeds this size will raise an error, or be
   truncated depending on the value of <em class="replaceable"><code>truncate-ok</code></em>
   (below).  Setting <em class="replaceable"><code>long-len</code></em> to zero and
   <em class="replaceable"><code>truncate-ok</code></em> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> will disable long
   fetching entirely.  If <em class="replaceable"><code>long-len</code></em> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
   or negative, defaults to 500k bytes.</dd><dt><span class="term"><em class="replaceable"><code>truncate-ok</code></em></span></dt><dd>Flag: if set, allow truncation of LONG columns to
   <em class="replaceable"><code>long-len</code></em> bytes on fetch; otherwise, fetches
   of LONG columns exceeding <em class="replaceable"><code>long-len</code></em> bytes
   will raise an error.  Default: <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</dd></dl></div></dd><dt><a id="ora-disconnect"></a><span class="term"><code class="code">(ORACLE:DISCONNECT)</code></span></dt><dd>
Disconnect from the database currently connected.  No more calls can
be made until <a class="link" href="#ora-connect"><code class="function">ORACLE:CONNECT</code></a> is called again.  The
connection is closed and removed from the connection cache.  Does
nothing if there is no connection.  <code class="function">DISCONNECT</code>
may not be called inside <code class="function">WITH-TRANSACTION</code>.
Returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
</dd><dt><a id="ora-run-sql"></a><span class="term"><code class="code">(ORACLE:RUN-SQL
<em class="replaceable"><code>sql</code></em>
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
<em class="replaceable"><code>params</code></em>
<em class="replaceable"><code>is-select</code></em>)</code></span></dt><dd><p class="simpara">Execute a SQL statement.  Must be <a class="link" href="#ora-connect"><code class="function">ORACLE:CONNECT</code></a>ed
to a database.  Returns the number of rows affected by the SQL operation,
for non-SELECT statements, zero for SELECT statements.  For
destructive database operations (INSERT, UPDATE, DELETE), the results
are committed to the database immediately if
<em class="replaceable"><code>auto-commit</code></em> when establishing the current
connection; see <a class="link" href="#ora-connect"><code class="function">ORACLE:CONNECT</code></a>.  The meaning of the
arguments is as follows: </p><div class="variablelist"><p class="title"><strong>Arguments for <code class="function">RUN-SQL</code></strong></p><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>sql</code></em></span></dt><dd>Text of SQL statement, as a string.
   The <em class="replaceable"><code>sql</code></em> statement may contain
   <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> "named parameters," e.g. ":myparam" whose values will
   be substituted from the parameters given
   in <em class="replaceable"><code>params</code></em>.
</dd><dt><span class="term"><em class="replaceable"><code>params</code></em></span></dt><dd>A mapping of the names of the bind-parameters in the
   query to their values.  The set of named parameters in the query must
   match exactly the keys mapped by <em class="replaceable"><code>params</code></em>.
   The mapping may be passed as either (1) a hash table whose keys are
   the named parameters or (2) a list of pairs, ((name value) (name
   value) ...).  Parameter values passed from Lisp are converted to the
   appropriate <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> data types (see <code class="function">FETCH</code>).
</dd><dt><span class="term"><em class="replaceable"><code>is-select</code></em></span></dt><dd>Flag: whether the statement is a SELECT query.  You
   usually do not need to set this as it is detected by default based on
   the SQL text.  However, there are situations, such as when a SELECT
   query begins with comment, that you need to specify it explicitly.
</dd></dl></div></dd><dt><a id="ora-do-rows"></a><span class="term"><code class="code">(ORACLE:DO-ROWS
<em class="replaceable"><code>vars</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> <em class="replaceable"><code>body</code></em>)</code></span></dt><dd><p class="simpara"> Macro which loops over a SQL SELECT result,
   evaluating, for each row in the result, the forms in <em class="replaceable"><code>body</code></em>,
   binding symbols given in <em class="replaceable"><code>vars</code></em> to
   corresponding database columns in the SELECT result.  The
   argument <em class="replaceable"><code>vars</code></em> must be a non-empty list of
   symbols matching a subset of the columns of an active SELECT query.
   If a SELECT column is an <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> expression such as
   <code class="literal">SUBSTR(mycol, 1, 10)</code>, it is recommended to use a
   column alias, e.g., <code class="literal">SELECT SUBSTR(mycol, 1, 10) AS
    myvar</code>, in which case the column alias will be used as the
   symbol bound to the column value.</p><p class="simpara">As <code class="function">DO-ROWS</code> expands into a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_docm_dost.html" target="_top"><code class="function">DO*</code></a>
   loop, it may be terminated prematurely, before all rows are fetched,
   by using <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_return.html" target="_top"><code class="function">RETURN</code></a> anywhere in <em class="replaceable"><code>body</code></em>.</p><p class="simpara">It is allowed to call <a class="link" href="#ora-connect"><code class="function">ORACLE:CONNECT</code></a> in the
   <em class="replaceable"><code>body</code></em> of the loop, but only to switch the connection to a database
   other than the one that was used to do the SELECT.  This is useful
   for reading from one database while writing to another.
  </p><p class="simpara">In <em class="replaceable"><code>vars</code></em>, instead of a single
   symbol, a pair (<em class="replaceable"><code>bound-var</code></em>
   <em class="replaceable"><code>"column-name"</code></em>) may be specified, which
   will cause values from the SELECTed column or alias ,
   <em class="replaceable"><code>column-name</code></em>, to be bound to Lisp variable,
   <em class="replaceable"><code>bound-var</code></em>.  This is for unusual cases
   where a Lisp variable cannot be created with the same name as the
   column (e.g., a column named "T"), or when it is inconvenient or
   impossible to alias the column with <code class="literal">SELECT ... AS</code>.
</p></dd><dt><a id="ora-fetch"></a><span class="term"><code class="code">(ORACLE:FETCH
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>result-type</code></em>)</code></span></dt><dd><p>Fetch a single row of data.  Returns a row of values
   corresponding to the columns of an active SELECT statment.  The row
   data is returned in one of three different forms, depending on the
   value of the symbol <em class="replaceable"><code>result-type</code></em>:
</p><div class="variablelist"><p class="title"><strong>Return values for <code class="function">FETCH</code></strong></p><dl class="variablelist"><dt><span class="term"><code class="classname">ARRAY</code></span></dt><dd>Values will be returned in an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_array.html" target="_top"><code class="classname">ARRAY</code></a> with the
    same number of columns as in the SELECT statement, in the same
    order.  This is the default.</dd><dt><span class="term"><code class="classname">PAIRS</code></span></dt><dd>A list of pairs, <code class="literal">((column, value)
     ...)</code> is be returned.  The number and order of pairs is
    the same as the columns in the SELECT statement.
 </dd><dt><span class="term"><code class="classname">HASH</code></span></dt><dd>A <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a> whose keys are the column names
    and whose values are the column values in the row.  The SELECT
    columns <span class="emphasis"><em>must be unique</em></span> and be valid Lisp
    symbols to use this option. If you are SELECTing an expression, you
    probably want to use a column alias: <code class="literal">SELECT &lt;expr&gt; AS
    some_alias ...</code></dd></dl></div><p>The following data type conversions are done between <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a>
 datatypes and <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> data types:
 </p><div class="informaltable"><a id="ora-fetch-data-types-tab"></a><table class="informaltable" border="1"><colgroup><col /><col /></colgroup><thead><tr><th><a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> type</th><th>Converts to/from <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> type</th></tr></thead><tbody><tr><td>Numeric (NUMBER, INTEGER, FLOAT)</td><td>The appropriate <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> numeric type (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_fixnum.html" target="_top"><code class="classname">FIXNUM</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_bignum.html" target="_top"><code class="classname">BIGNUM</code></a>,
      <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_float.html" target="_top"><code class="classname">FLOAT</code></a>)</td></tr><tr><td>String (CHAR, VARCHAR, VARCHAR2)</td><td>A <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>.  Note that CHAR will be padded out to its
      full, fixed length as defined in <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a>; VARCHAR will be a
      string of variable length.  Also note that <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> has no
      "zero-length string" value - it returns the SQL special value
      <code class="constant">NULL</code> which is converted to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> (see below).</td></tr><tr><td>DATE</td><td>A string of the form "YYYY-MM-DD HH:MM:SS" where HH is
      24-hour form.  If you want dates formatted differently, convert
      them to strings in <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> using <code class="literal">SELECT
       TO_CHAR(mydate, '<em class="replaceable"><code>template</code></em>') AS
       mydate</code>; the result will then be returned as a string,
      formatted as per <em class="replaceable"><code>template</code></em>.</td></tr><tr><td>RAW, LONG RAW</td><td>A hexadecimal string, with two hex digits for each byte of
      <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> data.  Note that this means the Lisp string will be
      twice the size, in bytes, as the <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> data.</td></tr><tr><td>"Large" types (LONG, BLOB, CLOB)</td><td>A Lisp string of (arbitrary, possibly binary) data.  Note
      that truncation may occur; see the <a class="link" href="#ora-connect"><code class="function">ORACLE:CONNECT</code></a>
      parameters <em class="replaceable"><code>long-len</code></em>
      and <em class="replaceable"><code>truncate-ok</code></em>.</td></tr><tr><td><code class="constant">NULL</code></td><td>The <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> value <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a></td></tr></tbody></table></div><p>
</p></dd><dt><a id="ora-fetch-all"></a><span class="term"><code class="code">(ORACLE:FETCH-ALL
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
<em class="replaceable"><code>max-rows</code></em>
<em class="replaceable"><code>result-type</code></em>
<em class="replaceable"><code>item-type</code></em>)</code></span></dt><dd><p class="simpara">Fetch some or all the rows from a query and return
result as a sequence of sequences.  Arguments are all optional:
<em class="replaceable"><code>max-rows</code></em> limits the result to
that numbers of rows;
<em class="replaceable"><code>result-type</code></em> is the type of
sequence of the rows, either
'<code class="classname">ARRAY</code> (the default) or
'<code class="classname">LIST</code>;
<em class="replaceable"><code>item-type</code></em> is the type of
sequence of the column values for each row, either
'<code class="classname">ARRAY</code> (the default) or
'<code class="classname">LIST</code>.
Each row fetched always contains the full set of column values SELECTed.
</p><p class="simpara">
<code class="function">FETCH-ALL</code> is often useful in conjunction with
<code class="function">MAP</code> or <code class="function">REDUCE</code> to iterate
over an entire SELECT result to construct a single Lisp value.

</p></dd><dt><a id="ora-peek"></a><span class="term"><code class="code">(ORACLE:PEEK <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
   <em class="replaceable"><code>result-type</code></em>)</code></span></dt><dd>

Peek at next row of data (without fetching it).  Returns a row a la
<code class="function">FETCH</code>, except does not advance to the next row.
Repeated calls to <code class="function">PEEK</code> will thus return the same
row of data.  Returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if at EOF.  If data is available, returns
row data just as <code class="function">FETCH</code> (see
<code class="function">FETCH</code> for data format and conversions done).
Optional argument <em class="replaceable"><code>result-type</code></em> is the type
of sequence of the column values for the returned row, either
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_array.html" target="_top"><code class="classname">ARRAY</code></a> (the default) or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>.
<code class="function">PEEK</code> is a useful look-ahead
for database reporting functions that may need to "break" on changes in
data to print headers, summaries, etc.
</dd><dt><a id="ora-columns"></a><span class="term"><code class="code">(ORACLE:COLUMNS)</code></span></dt><dd><p>Returns information on the columns of a SELECT
  result, in the form of an array of SQLCOL structures, one for each
  result column in the most recent SELECT statement.  It is not
  necessary to have called <code class="function">FETCH</code> before requesting
  column information on the query, however the query must have been
  compiled and executed with <code class="function">RUN-SQL</code>.  Each SQLCOL
  structure has these slots:
</p><div class="variablelist"><p class="title"><strong>Slots of <code class="classname">SQLCOL</code></strong></p><dl class="variablelist"><dt><span class="term">NAME</span></dt><dd>The <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> column name or the expression
    selected.  If the query used a column alias, <code class="literal">SELECT
     <em class="replaceable"><code>expr</code></em> AS
     <em class="replaceable"><code>alias</code></em></code>, then
    <em class="replaceable"><code>alias</code></em> will be returned as the column name.
 </dd><dt><span class="term">TYPE</span></dt><dd><a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> data type (VARCHAR, NUMBER, DATE, ...)
 </dd><dt><span class="term">SIZE</span></dt><dd><a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> data length (useful mostly for
    character types)</dd><dt><span class="term">SCALE</span></dt><dd>For numeric (NUMBER) types, number of digits to right of
    decimal; NIL for FLOAT</dd><dt><span class="term">PRECISION</span></dt><dd>For numeric types, total number of significant
    digits (decimal digits for NUMBER, bits for FLOAT)</dd><dt><span class="term">NULL_OK</span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> if <code class="constant">NULL</code>s allowed, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if <code class="constant">NULL</code>s are
    not allowed.</dd></dl></div><p class="simpara">To access the values of the SQLCOL structures, use the standard
 accessor functions, e.g., <code class="literal">(ORACLE:SQLCOL-NAME (elt
  (ORACLE:COLUMNS) 0))</code></p></dd><dt><a id="ora-eof"></a><span class="term"><code class="code">(ORACLE:EOF)</code></span></dt><dd>
Returns EOF status.  A SELECT query cursor is considered at EOF if the next
FETCH would return no data.  Must be connected to a database, and have
an active SELECT statement.
</dd><dt><a id="ora-insert-row"></a><span class="term"><code class="code">(ORACLE:INSERT-ROW
<em class="replaceable"><code>table</code></em>
<em class="replaceable"><code>values</code></em>)</code></span></dt><dd>
Inserts a single row into <em class="replaceable"><code>table</code></em>.
Second argument <em class="replaceable"><code>values</code></em> is a map of
column names to values: either a hash table whose keys are the column
names, or a list of (name, value) pairs.  Columns missing from the map
will be given the default <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> value, or <code class="constant">NULL</code>.
Returns the number of rows inserted (i.e., always 1).
</dd><dt><a id="ora-update-row"></a><span class="term"><code class="code">(ORACLE:UPDATE-ROW
<em class="replaceable"><code>table</code></em>
<em class="replaceable"><code>condition</code></em>
<em class="replaceable"><code>vals</code></em>
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
<em class="replaceable"><code>params</code></em>)</code></span></dt><dd>
Updates rows in <em class="replaceable"><code>table</code></em>.  Second argument
<em class="replaceable"><code>condition</code></em> is a string expression for a WHERE
clause (without the "WHERE") which determines which rows are updated.
Third argument <em class="replaceable"><code>vals</code></em> is a map of columns to
be updated to their new values: a hash table whose keys are column
names, or list of (name, value) pairs.  Optional
<em class="replaceable"><code>params</code></em> specifies values for named
parameters that may occur in <em class="replaceable"><code>condition</code></em>,
e.g., when the condition is a match on a primary key, e.g.: <code class="literal">"pk_column
= :pk_val"</code>.  Returns the number of rows updated.
</dd><dt><a id="ora-row-count"></a><span class="term"><code class="code">(ORACLE:ROW-COUNT)</code></span></dt><dd>
For SELECT statements, returns the number of rows
<code class="function">FETCH</code>ed (<span class="strong"><strong>not</strong></span>
<code class="function">PEEK</code>ed) so far.  For other statements (e.g.,
INSERT, UPDATE, DELETE), returns the number of rows affected by the
last operation (e.g., inserted, updated, deleted).  Must be connected
to a database and have an active SQL statement.
</dd><dt><a id="ora-with-transaction"></a><span class="term"><code class="code">(ORACLE:WITH-TRANSACTION
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a>
<em class="replaceable"><code>body</code></em>)</code></span></dt><dd>

Evaluates the forms in <em class="replaceable"><code>body</code></em> atomically as a
database transaction, ensuring that either all the database operations
done in <em class="replaceable"><code>body</code></em> complete successfully, or none
of them do.  If pending (un-committed) changes exist when this macro
is entered, they are <span class="emphasis"><em>rolled back</em></span> (undone), so
that the database is affected only by the subsequent updates inside
<em class="replaceable"><code>body</code></em>.  Nesting of
<code class="function">WITH-TRANSACTION</code> blocks is not allowed and will
raise an error.  There is no effect on the status of
<em class="replaceable"><code>auto-commit</code></em> given in
<a class="link" href="#ora-connect"><code class="function">ORACLE:CONNECT</code></a>; it resumes its previous state when the
macro exits.  The value of the <code class="function">WITH-TRANSACTION</code>
expression is that of the last form in <em class="replaceable"><code>body</code></em>.
</dd><dt><a id="ora-commit"></a><span class="term"><code class="code">(ORACLE:COMMIT)</code></span></dt><dd>
Commits (makes permanent) any pending changes to the database.  The
<em class="replaceable"><code>auto-commit</code></em> parameter to
<a class="link" href="#ora-connect"><code class="function">ORACLE:CONNECT</code></a> must not have been set to use this
function, nor can it be called inside a
<code class="function">WITH-TRANSACTION</code> block. Always returns NIL.
</dd><dt><a id="ora-rollback"></a><span class="term"><code class="code">(ORACLE:ROLLBACK)</code></span></dt><dd>
Rolls back (undoes and abandons) any pending changes to the database.
The <em class="replaceable"><code>auto-commit</code></em> parameter to
<a class="link" href="#ora-connect"><code class="function">ORACLE:CONNECT</code></a> must not have been set to use this
function, nor can it be called inside a
<code class="function">WITH-TRANSACTION</code> block. Always returns NIL.
</dd><dt><a id="ora-auto-commit"></a><span class="term"><code class="code">(ORACLE:AUTO-COMMIT)</code></span></dt><dd>
Toggles the state of <em class="replaceable"><code>auto-commit</code></em> initially
given to <a class="link" href="#ora-connect"><code class="function">ORACLE:CONNECT</code></a> for the current connection.
With <em class="replaceable"><code>auto-commit</code></em> enabled, modifications to
the database are committed (made permanent) after each destructive SQL
operation made with calls to <code class="function">RUN-SQL</code>,
<code class="function">INSERT-ROW</code>, <code class="function">UPDATE_ROW</code>, etc.
With <em class="replaceable"><code>auto-commit</code></em> disabled, transactional
integrity is under the programmer's control and is managed either by
(1) explicitly calling <code class="function">COMMIT</code> or
<code class="function">ROLLBACK</code> to commit or undo the pending
operations, or (2) wrapping code blocks with database operations
inside the <code class="function">WITH-TRANSACTION</code> macro.
<code class="function">AUTO-COMMIT</code> returns the previous status of
<em class="replaceable"><code>auto-commit</code></em>.
<code class="function">AUTO-COMMIT</code> may not be called inside
<code class="function">WITH-TRANSACTION</code>.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="ora-example"></a>33.10.2. <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> Example</h3></div></div></div><p>
Below is a simple example script which uses <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a>'s demo database
schema, <code class="literal">SCOTT</code>.

</p><pre class="programlisting">
(setf server "orcl") <strong>	; </strong><em class="lineannotation"><span class="lineannotation">; Change this to your server's SID</span></em>
(oracle:connect "scott" "tiger" server)

(oracle:run-sql "SELECT deptno, dname, loc FROM dept ORDER BY DNAME")
(oracle:do-rows (deptno dname loc)
  (format t "Dept. no is '~A', " deptno)
  (format t "Dept. name is '~A', " dname)
  (format t "Dept. loc is '~A'~%" loc))

(oracle:update-row "dept" "dname = :acctval" '(("dname" "NEWACCT")) '(("acctval" "ACCOUNTING")))

(oracle:run-sql "SELECT deptno, dname, loc FROM dept ORDER BY DNAME")
(oracle:do-rows (deptno dname loc)
  (format t "Dept. no is '~A', " deptno)
  (format t "Dept. name is '~A', " dname)
  (format t "Dept. loc is '~A'~%" loc))

(oracle:update-row "dept" "dname = :acctval" '(("dname" "ACCOUNTING")) '(("acctval" "NEWACCT")))
</pre><p>
</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="ora-config"></a>33.10.3. <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> Configuration</h3></div></div></div><p>Obviously, a working <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> environment is required.  It is
recommended that you first be able to log on and use the <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a>
SQL*Plus application to test your environment
<span class="strong"><strong>before</strong></span> attempting <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> access via the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> module.
At a minimum you will need to set environment variables
<code class="envar">ORACLE_HOME</code> to the <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> base directory and
<code class="envar">LD_LIBRARY_PATH</code> to include
<code class="literal">$<code class="envar">ORACLE_HOME</code>/lib</code> and possibly other
directories.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="ora-build"></a>33.10.4. Building the <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> Interface</h3></div></div></div><p>The module uses the <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a> Call Interface (<a class="ulink" href="http://www.vivtek.com/oracle.html" target="_top">OCI</a>)
<a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> library.  To build the module you will need the <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a>
<a class="ulink" href="http://www.vivtek.com/oracle.html" target="_top">OCI</a> headers and link libraries; as a quick check, make sure
you have the file <code class="filename">oci.h</code> somewhere
under <code class="envar">ORACLE_HOME</code>, probably
in <code class="filename">$<code class="envar">ORACLE_HOME</code>/rdbms/demo/oci.h</code>.</p><p>To build the module into <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>, configure with
<span class="command"><strong>./configure ... --with-module=oracle ...</strong></span>.
The <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>full</strong></span></a> <a href="impnotes.html#linkset" class="olink">linking set</a> will contain the module,
so you will need to use the <code class="option"><a href="clisp.html#opt-link-set" class="olink">-K</a></code> option to use it.
You can test that you really have the <a class="ulink" href="http://www.oracle.com" target="_top">Oracle</a>-enabled <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> by
evaluating <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_describe.html" target="_top"><code class="function">DESCRIBE</code></a> 'oracle:connect)</code>.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>It may be necessary to edit file
<a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/oracle/Makefile.in"><code class="filename">modules/oracle/Makefile.in</code></a>
prior to running <span class="command"><strong>./configure</strong></span>.</p></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="libsvm"></a>33.11. LibSVM Interface</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#libsvm-types">33.11.1. Types</a></span></dt><dt><span class="section"><a href="#libsvm-output">33.11.2. Output</a></span></dt><dt><span class="section"><a href="#libsvm-functions">33.11.3. Functions</a></span></dt><dd><dl><dt><span class="section"><a href="#libsvm-functions-problem">33.11.3.1. Functions related to <span class="type">problem</span></a></span></dt><dt><span class="section"><a href="#libsvm-functions-model">33.11.3.2. Functions related to <span class="type">model</span></a></span></dt><dt><span class="section"><a href="#libsvm-functions-parameter">33.11.3.3. Functions related to <span class="type">parameter</span></a></span></dt></dl></dd></dl></div><p>This is an <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>-based interface to <a class="ulink" href="http://www.csie.ntu.edu.tw/~cjlin/libsvm/" target="_top">LibSVM</a>.</p><p>The package <strong class="package"><span class="quote">“<span class="quote">LIBSVM</span>”</span></strong> is <a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-SENSITIVE</code></a>,
 and you do not need the <code class="function">svm_</code> prefix.</p><p>When this module is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a>
 contains the symbol <code class="constant">:LIBSVM</code>.</p><p>See <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/libsvm/test.tst"><code class="filename">modules/libsvm/test.tst</code></a>
 for sample usage.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="libsvm-types"></a>33.11.1. Types</h3></div></div></div><p>All data is kept on the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> side as much as possible, so
 these foreign types do <span class="strong"><strong>not</strong></span> have a <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> counterpart.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="type">node</span></span></dt><dd>Corresponds to <span class="type">svm_node</span>, represented
    as a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> on the lisp side.</dd><dt><span class="term"><span class="type">problem</span></span></dt><dd>Corresponds to <span class="type">svm_problem</span>, represented
    as a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> on the lisp side.</dd><dt><span class="term"><span class="type">parameter</span></span></dt><dd>Corresponds to <span class="type">svm_parameter</span>, represented
    as a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> on the lisp side.</dd><dt><span class="term"><span class="type">model</span></span></dt><dd>Corresponds to <span class="type">svm_model</span>, an opaque
    <a class="link" href="#fptr"><code class="classname">FFI:FOREIGN-POINTER</code></a>.</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="libsvm-output"></a>33.11.2. Output</h3></div></div></div><p>The output from the library functions goes to
 <code class="varname">*libsvm-output*</code>, which is initialized to
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-OUTPUT*</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="libsvm-functions"></a>33.11.3. Functions</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#libsvm-functions-problem">33.11.3.1. Functions related to <span class="type">problem</span></a></span></dt><dt><span class="section"><a href="#libsvm-functions-model">33.11.3.2. Functions related to <span class="type">model</span></a></span></dt><dt><span class="section"><a href="#libsvm-functions-parameter">33.11.3.3. Functions related to <span class="type">parameter</span></a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="libsvm-functions-problem"></a>33.11.3.1. Functions related to <span class="type">problem</span></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">(problem-l <em class="replaceable"><code>problem</code></em>)</code></span></dt><dd>Return the number of rows in the <em class="replaceable"><code>problem</code></em> (a
    <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a>)</dd><dt><span class="term"><code class="code">(problem-y <em class="replaceable"><code>problem</code></em>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> (<em class="replaceable"><code>length</code></em> (problem-l <em class="replaceable"><code>problem</code></em>)))</code></span></dt><dd>Return a <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">DOUBLE-FLOAT</code></a> <em class="replaceable"><code>length</code></em>)</code></span> representing the targets in the
    <em class="replaceable"><code>problem</code></em> (a <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a>).</dd><dt><span class="term"><code class="code">(problem-y-n <em class="replaceable"><code>problem</code></em>
    <em class="replaceable"><code>n</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> (<em class="replaceable"><code>length</code></em> (problem-l <em class="replaceable"><code>problem</code></em>))))</code></span></dt><dd>Return the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">DOUBLE-FLOAT</code></a> representing the <em class="replaceable"><code>n</code></em>th
    target in the <em class="replaceable"><code>problem</code></em> (a <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a>).
 </dd><dt><span class="term"><code class="code">(problem-x <em class="replaceable"><code>problem</code></em>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> (<em class="replaceable"><code>length</code></em> (problem-l <em class="replaceable"><code>problem</code></em>)))</code></span></dt><dd>Return a <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a>
     node) <em class="replaceable"><code>length</code></em>)</code></span> representing the predictors in the <em class="replaceable"><code>problem</code></em>
    (a <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a>).</dd><dt><span class="term"><code class="code">(problem-x-n <em class="replaceable"><code>problem</code></em>
    <em class="replaceable"><code>n</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> (<em class="replaceable"><code>length</code></em> (problem-l <em class="replaceable"><code>problem</code></em>))))</code></span></dt><dd>Return the <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> node)</code></span>
    representing the <em class="replaceable"><code>n</code></em>th set of predictors in the <em class="replaceable"><code>problem</code></em> (a
    <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a>).</dd><dt><span class="term"><code class="code">(make-problem <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> <em class="replaceable"><code>l</code></em> <em class="replaceable"><code>y</code></em>
    <em class="replaceable"><code>x</code></em>)</code></span></dt><dd>Allocate a <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a> representing
    a <span class="type">model</span>.</dd><dt><span class="term"><code class="code">(destroy-problem <em class="replaceable"><code>problem</code></em>)</code></span></dt><dd><p class="simpara">Release the memory taken by the <span class="type">problem</span>
    object and invalidate the <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a> <em class="replaceable"><code>problem</code></em>.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>You <span class="strong"><strong>must</strong></span> call this function yourself, but only
     <span class="strong"><strong>after</strong></span> deallocating all <span class="type">model</span> objects trained from
     this <em class="replaceable"><code>problem</code></em>.</p></div></dd><dt><span class="term"><code class="code">(load-problem <em class="replaceable"><code>filename</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    (<em class="replaceable"><code>log</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-OUTPUT*</code></a>))</code></span></dt><dd><p class="simpara">Read a <span class="type">problem</span> from a file in the
    libsvm/svmlight format. Return two values: the <span class="type">problem</span>
    and max index (i.e., the number of columns).</p><p class="simpara">Messages go to <em class="replaceable"><code>log</code></em>.</p></dd><dt><span class="term"><code class="code">(save-problem <em class="replaceable"><code>filename</code></em> <em class="replaceable"><code>problem</code></em>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> (<em class="replaceable"><code>log</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stdebug-i_ace-outputst.html" target="_top"><code class="varname">*STANDARD-OUTPUT*</code></a>))</code></span></dt><dd><p class="simpara">Write a <span class="type">problem</span> into a file.</p><p class="simpara">Messages go to <em class="replaceable"><code>log</code></em>.</p></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="libsvm-functions-model"></a>33.11.3.2. Functions related to <span class="type">model</span></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">(destroy-model <em class="replaceable"><code>model</code></em>)</code></span></dt><dd><p class="simpara">Release the memory taken by the <span class="type">model</span>
    object and invalidate the <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a> <em class="replaceable"><code>model</code></em>.</p><p class="simpara">Calls <code class="function">svm_destroy_model</code> or
    <code class="function">svm_svm_free_and_destroy_model</code>.</p><p class="simpara">You do <span class="strong"><strong>not</strong></span> have to call this function yourself, it is
    attached to the <em class="replaceable"><code>model</code></em> by <code class="function">train</code>
    and <code class="function">load-model</code> via <a class="link" href="#final" title="31.8. Finalization"><code class="function">EXT:FINALIZE</code></a>.</p></dd><dt><span class="term"><code class="code">(check-parameter <em class="replaceable"><code>problem</code></em> <em class="replaceable"><code>parameter</code></em>)</code></span></dt><dd><p class="simpara">Check if the <em class="replaceable"><code>parameter</code></em> is appropriate for the
    <em class="replaceable"><code>problem</code></em>.</p><p class="simpara">Calls <code class="function">svm_check_parameter</code>.</p></dd><dt><span class="term"><code class="code">(train <em class="replaceable"><code>problem</code></em> <em class="replaceable"><code>parameter</code></em>)</code></span></dt><dd><p class="simpara">Train a <span class="type">model</span>.</p><p class="simpara">Calls <code class="function">svm_train</code>
    and <code class="function">check-parameter</code>.</p></dd><dt><span class="term"><code class="code">(cross-validation <em class="replaceable"><code>problem</code></em> <em class="replaceable"><code>parameter</code></em>
    <em class="replaceable"><code>n</code></em>)</code></span></dt><dd><p class="simpara">Run <em class="replaceable"><code>n</code></em>-fold cross-validation.</p><p class="simpara">Calls <code class="function">svm_cross_validation</code>
    and <code class="function">check-parameter</code>.</p></dd><dt><span class="term"><code class="code">(save-model <em class="replaceable"><code>filename</code></em> <em class="replaceable"><code>model</code></em>)</code></span></dt><dd><p class="simpara">Write a <span class="type">model</span> into a file.</p><p class="simpara">Calls <code class="function">svm_save_model</code>.</p></dd><dt><span class="term"><code class="code">(load-model <em class="replaceable"><code>filename</code></em>)</code></span></dt><dd><p class="simpara">Read a <span class="type">model</span> from a file.</p><p class="simpara">Calls <code class="function">svm_load_model</code>.</p></dd><dt><span class="term"><code class="code">(get-svm-type <em class="replaceable"><code>model</code></em>)</code></span></dt><dd>Call <code class="function">svm_get_svm_type</code>.
 </dd><dt><span class="term"><code class="code">(get-nr-class <em class="replaceable"><code>model</code></em>)</code></span></dt><dd>Call <code class="function">svm_get_nr_class</code>.
 </dd><dt><span class="term"><code class="code">(get-labels <em class="replaceable"><code>model</code></em>)</code></span></dt><dd>Call <code class="function">svm_get_labels</code>.
 </dd><dt><span class="term"><code class="code">(get-svr-probability <em class="replaceable"><code>model</code></em>)</code></span></dt><dd>Call <code class="function">svm_get_svr_probability</code>.
 </dd><dt><span class="term"><code class="code">(predict-values <em class="replaceable"><code>model</code></em> <em class="replaceable"><code>x</code></em>)</code></span></dt><dd><p class="simpara">Return the decision values
    (a <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">DOUBLE-FLOAT</code></a>)</code></span>) given
    by <em class="replaceable"><code>model</code></em> for <em class="replaceable"><code>x</code></em> (a <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> node)</code></span>).
   </p><p class="simpara">Calls <code class="function">svm_predict_values</code>.</p></dd><dt><span class="term"><code class="code">(predict <em class="replaceable"><code>model</code></em> <em class="replaceable"><code>x</code></em>)</code></span></dt><dd>Call <code class="function">svm_predict</code>.
 </dd><dt><span class="term"><code class="code">(predict-probability <em class="replaceable"><code>model</code></em> <em class="replaceable"><code>x</code></em>)</code></span></dt><dd>Call <code class="function">svm_predict_probability</code>.
 </dd><dt><span class="term"><code class="code">(check-probability-model <em class="replaceable"><code>model</code></em>)</code></span></dt><dd>Call <code class="function">svm_check_probability_model</code>.
 </dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="libsvm-functions-parameter"></a>33.11.3.3. Functions related to <span class="type">parameter</span></h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">(destroy-parameter <em class="replaceable"><code>parameter</code></em>)</code></span></dt><dd><p class="simpara">Release the memory taken by the <span class="type">parameter</span>
    object and invalidate the <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a> <em class="replaceable"><code>parameter</code></em>.</p><p class="simpara">Does <span class="strong"><strong>not</strong></span> call <code class="function">svm_destroy_param</code>.</p><p class="simpara">You do <span class="strong"><strong>not</strong></span> have to call this function yourself, it is
    attached to the <em class="replaceable"><code>parameter</code></em> by <code class="function">make-parameter</code>
    via <a class="link" href="#final" title="31.8. Finalization"><code class="function">EXT:FINALIZE</code></a>.</p></dd><dt><span class="term"><code class="code">(make-parameter <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :v svm_type
    kernel_type degree gamma coef0 cache_size eps C nr_weight
    weight_label weight nu p shrinking probability)</code></span></dt><dd><p class="simpara">Allocates a new <a class="link" href="#dffi-variables" title="32.3.5. Foreign variables"><code class="classname">FFI:FOREIGN-VARIABLE</code></a> of
    type <span class="type">parameter</span> with the supplied slots.</p><p class="simpara">The defaults come from vector <em class="replaceable"><code>v</code></em> (such as returned
    by <code class="code">(<a class="link" href="#foreign-value"><code class="function">FFI:FOREIGN-VALUE</code></a> <em class="replaceable"><code>parameter</code></em>)</code>), if supplied, providing
    an easy way to copy <em class="replaceable"><code>parameter</code></em>s, otherwise the defaults
    for <span class="command"><strong>svm-train</strong></span> are used.</p></dd><dt><span class="term"><code class="code">(parameter-alist <em class="replaceable"><code>parameter</code></em>)</code></span></dt><dd>Return the <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_a.html#association_list">association list</a> representing <em class="replaceable"><code>parameter</code></em>.
 </dd></dl></div></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="pari"></a>33.12. Computer Algebra System PARI</h2></div></div></div><p>This package offers an <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>-based interface to <a class="ulink" href="http://pari.math.u-bordeaux.fr/" target="_top">PARI</a>.</p><p>The package <strong class="package"><span class="quote">“<span class="quote">PARI</span>”</span></strong>
 is <a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-SENSITIVE</code></a>.</p><p>When this module is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a> contains the
 symbol <code class="constant">:PARI</code>.</p><p>PARI objects are printed and read using a special
 <span class="data"><code class="literal">#Z""</code></span> syntax.</p><p>Most functions accept lisp objects as well as PARI objects and
return PARI objects, which can be converted to lisp using the
<code class="function">pari:pari-to-lisp</code> function.</p><p>See <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/pari/test.tst"><code class="filename">modules/pari/test.tst</code></a>
 for sample usage.</p><div class="simplesect"><div class="titlepage"><div><div><h3 class="title"><a id="pari-ext"></a>Extending the module</h3></div></div></div><p>Not all PARI functions have a corresponding lisp function yet, but one
remedy that with just a few lines: </p><pre class="programlisting">
(<a class="link" href="#dffi-default-lib"><code class="function">FFI:DEFAULT-FOREIGN-LIBRARY</code></a> "libpari.so") ; or pari.dll on <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>
(pari:pari-call-out (matrix-rank ffi:long) "rank" (x))<strong>	; </strong><em class="lineannotation"><span class="lineannotation">long rank(GEN x);</span></em>
(pari:pari-call-out fibonacci "fibo" ((n ffi:long)))<strong>	; </strong><em class="lineannotation"><span class="lineannotation">GEN fibo(long n);</span></em>
(pari:pari-call-out-prec pari-arctan "gatan" (x))<strong>	; </strong><em class="lineannotation"><span class="lineannotation">GEN gatan(GEN x, long prec);</span></em>
(pari:pari-call-out (equal? boolean) "gequal" (x y))<strong>	; </strong><em class="lineannotation"><span class="lineannotation">GEN gequal(GEN x, GEN y);</span></em>
</pre><p>
(Actually, these four functions are already present in the module.)
Please feel free to submit additions for
 <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/pari/pari.lisp"><code class="filename">modules/pari/pari.lisp</code></a>
 and <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/pari/test.tst"><code class="filename">modules/pari/test.tst</code></a>.</p></div><div class="simplesect"><div class="titlepage"><div><div><h3 class="title"><a id="pari-prec"></a>Real precision</h3></div></div></div><p>The real precision defaults to <code class="varname">pari:pari-real-precision</code>
which specifies the default precision in decimal digits:
</p><pre class="programlisting">
pari:pari-real-precision
⇒ <code class="computeroutput">19</code>
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_length.html" target="_top"><code class="function">LENGTH</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_write-to-_nc-to-string.html" target="_top"><code class="function">PRIN1-TO-STRING</code></a> (pari:pari-to-lisp (pari:pari-pi))))
⇒ <code class="computeroutput">23</code>
</pre><p>
One can also pass the precision parameter explicitly:
</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_length.html" target="_top"><code class="function">LENGTH</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_write-to-_nc-to-string.html" target="_top"><code class="function">PRIN1-TO-STRING</code></a> (pari:pari-to-lisp (pari:pari-pi :prec 38))))
⇒ <code class="computeroutput">41</code>
</pre><p>
Note that the <span class="emphasis"><em>actual</em></span> precision is determined by the
size of the mantissa which can be incremented only in steps of
<code class="code">(<a class="link" href="#bitsizeof"><code class="function">FFI:BITSIZEOF</code></a> 'ffi:ulong)</code> (64 bits or 32 bits).</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="matlab"></a>33.13. Matlab Interface</h2></div></div></div><p>This is an interface to the
 <a class="matlab" href="http://www.mathworks.com/access/helpdesk/help/techdoc/apiref/">Matlab C API</a>.</p><p>The package <strong class="package"><span class="quote">“<span class="quote">MATLAB</span>”</span></strong> is <a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-SENSITIVE</code></a>,
 so you would write <code class="code">(matlab:engOpen ...)</code>
 when you need to call <a class="matlab" href="http://www.mathworks.com/access/helpdesk/help/techdoc/apiref/engopen.html"><code class="function">engOpen</code></a>.</p><p>When this module is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a>
 contains the symbol <code class="constant">:MATLAB</code>.</p><p>Additionally, some higher level functionality is available
 (see <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/matlab/test.tst"><code class="filename">modules/matlab/test.tst</code></a>
 for sample usage):</p><div class="variablelist"><dl class="variablelist"><dt><a id="matlab-matfile-content"></a><span class="term"><code class="code">(matlab:matfile-content mf)</code></span></dt><dd>Return a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>s naming the
   variables in file <em class="replaceable"><code>mf</code></em>
   (opened using <a class="matlab" href="http://www.mathworks.com/access/helpdesk/help/techdoc/apiref/matopen.html"><code class="function">matOpen</code></a>).
</dd><dt><a id="matlab-command"></a><span class="term"><code class="varname">matlab:*command*</code></span></dt><dd>The default argument to
   <a class="matlab" href="http://www.mathworks.com/access/helpdesk/help/techdoc/apiref/engopen.html"><code class="function">engOpen</code></a>.
</dd><dt><a id="matlab-engine-v"></a><span class="term"><code class="varname">matlab:*engine*</code></span></dt><dd>The currrently open Matlab engine.
</dd><dt><a id="matlab-engine-f"></a><span class="term"><code class="code">(matlab:engine)</code></span></dt><dd>Make sure <code class="varname">*engine*</code> is valid and
   return it.</dd><dt><a id="matlab-with-engine"></a><span class="term"><code class="code">(matlab:with-engine
   (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> engine command) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> <em class="replaceable"><code>body</code></em>)</code></span></dt><dd>Run the <em class="replaceable"><code>body</code></em> wuth the <em class="replaceable"><code>engine</code></em>
   bound to a Matlab engine (default <code class="varname">*engine*</code>).
   The engine is opened with <a class="matlab" href="http://www.mathworks.com/access/helpdesk/help/techdoc/apiref/engopen.html"><code class="function">engOpen</code></a>,
   then closed with <a class="matlab" href="http://www.mathworks.com/access/helpdesk/help/techdoc/apiref/engclose.html"><code class="function">engClose</code></a>.
</dd><dt><a id="matlab-with-MATfile"></a><span class="term"><code class="code">(matlab:with-MATfile
   (file name <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> mode) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> <em class="replaceable"><code>body</code></em>)</code></span></dt><dd><a class="matlab" href="http://www.mathworks.com/access/helpdesk/help/techdoc/apiref/matopen.html"><code class="function">matOpen</code></a> the
   matlab file, do the <em class="replaceable"><code>body</code></em>, <a class="matlab" href="http://www.mathworks.com/access/helpdesk/help/techdoc/apiref/matclose.html"><code class="function">matClose</code></a>
   it.</dd><dt><a id="copy-lisp-to-mxArray"></a><span class="term"><code class="code">(matlab:copy-lisp-to-mxArray
   lisp-array <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> matlab-matrix)</code></span></dt><dd>Copy data from the 2-dimensional lisp array to the
  Matlab matrix.</dd><dt><a id="copy-lisp-to-matlab"></a><span class="term"><code class="code">(matlab:copy-lisp-to-matlab
   lisp-array matlab-variable <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> engine)</code></span></dt><dd>Copy the 2-dimensional lisp array to the Matlab
  variable (a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>) in the supplied engine (defaults to
  <code class="varname">*engine*</code>).</dd><dt><a id="copy-mxArray-to-lisp"></a><span class="term"><code class="code">(matlab:copy-mxArray-to-lisp
   matlab-matrix <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> lisp-array)</code></span></dt><dd>Copy the matlab matrix to the 2-dimensional lisp array
   (created anew or re-used if supplied).</dd><dt><a id="copy-matlab-to-lisp"></a><span class="term"><code class="code">(matlab:copy-matlab-to-lisp
   matlab-variable <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> lisp-array <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> engine)</code></span></dt><dd>Copy data from the matlab variable to the
   2-dimensional lisp array
   (created anew or re-used if supplied).</dd><dt><a id="matlab-invert-matrix"></a><span class="term"><code class="code">(matlab:invert-matrix
   lisp-array <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> engine)</code></span></dt><dd>Invert the lisp matrix using the specified engine.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="netica"></a>33.14. Netica Interface</h2></div></div></div><p>This is an interface to the <a class="ulink" href="http://norsys.com/netica_c_api.htm" target="_top">Netica C API</a> (<a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> API version 3.25)
 for working with Bayesian belief networks and influence diagrams.</p><p>The package <strong class="package"><span class="quote">“<span class="quote">NETICA</span>”</span></strong> is <a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-SENSITIVE</code></a>,
 e.g., you would write <code class="code">(netica:GetNodeExpectedUtils_bn ...)</code>
 when you need to call
 <a class="netica" href="http://norsys.com/onLineAPIManual/functions/GetNodeExpectedUtils_bn.html"><code class="function">GetNodeExpectedUtils_bn</code></a>.</p><p>When this module is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a>
 contains the symbol <code class="constant">:NETICA</code>.</p><p>All public <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> functions are available as
 <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a>s.</p><p>The functions which are specified to return <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> arrays,
namely </p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="netica" href="http://norsys.com/onLineAPIManual/functions/GetNodeBeliefs_bn.html"><code class="function">GetNodeBeliefs_bn</code></a></td></tr><tr><td><a class="netica" href="http://norsys.com/onLineAPIManual/functions/GetNodeExpectedUtils_bn.html"><code class="function">GetNodeExpectedUtils_bn</code></a></td></tr><tr><td><a class="netica" href="http://norsys.com/onLineAPIManual/functions/GetNodeLikelihood_bn.html"><code class="function">GetNodeLikelihood_bn</code></a></td></tr><tr><td><a class="netica" href="http://norsys.com/onLineAPIManual/functions/GetNodeProbs_bn.html"><code class="function">GetNodeProbs_bn</code></a></td></tr><tr><td><a class="netica" href="http://norsys.com/onLineAPIManual/functions/GetNodeLevels_bn.html"><code class="function">GetNodeLevels_bn</code></a></td></tr></table><p> correspond to <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a>s which return <a class="link" href="#c-pointer"><span class="type">FFI:C-POINTER</span></a>s.
 We define low level wrappers for them, namely </p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="function">GetNodeBeliefs</code></td></tr><tr><td><code class="function">GetNodeExpectedUtils</code></td></tr><tr><td><code class="function">GetNodeLikelihood</code></td></tr><tr><td><code class="function">GetNodeProbs</code></td></tr><tr><td><code class="function">GetNodeLevels</code></td></tr></table><p> which return the appropriate <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a>s.</p><p>Additionally, some higher level functionality is available
 (see <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/netica/demo.lisp"><code class="filename">modules/netica/demo.lisp</code></a>
 for sample usage):</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">(netica:start-netica <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   :license :verbose)</code></span></dt><dd>Call <a class="netica" href="http://norsys.com/onLineAPIManual/functions/NewNeticaEnviron_ns.html"><code class="function">NewNeticaEnviron_ns</code></a>
   and <a class="netica" href="http://norsys.com/onLineAPIManual/functions/InitNetica2_bn.html"><code class="function">InitNetica2_bn</code></a> and print some
   statistics; initialize <code class="varname">netica:*env*</code>.
</dd><dt><span class="term"><code class="code">(netica:check-errors <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   :env :clear :severity)</code></span></dt><dd>Show and, optionally, clear
   (<a class="netica" href="http://norsys.com/onLineAPIManual/functions/ClearError_ns.html"><code class="function">ClearError_ns</code></a>), the errors of the
   given severity (<a class="netica" href="http://norsys.com/onLineAPIManual/functions/ErrorSeverity_ns.html"><code class="function">ErrorSeverity_ns</code></a>)
   and above.
   You should call this function after <span class="emphasis"><em>every</em></span> call
   to a Netica function.  Every wrapper function in this list calls it,
   so you do <span class="strong"><strong>not</strong></span> need to call it after a call to a wrapper function.
</dd><dt><span class="term"><code class="code">(netica:error-message error)</code></span></dt><dd><p>Convert netica error to a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> containing</p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="netica" href="http://norsys.com/onLineAPIManual/functions/ErrorCategory_ns.html"><code class="function">ErrorCategory_ns</code></a></td></tr><tr><td><a class="netica" href="http://norsys.com/onLineAPIManual/functions/ErrorSeverity_ns.html"><code class="function">ErrorSeverity_ns</code></a></td></tr><tr><td><a class="netica" href="http://norsys.com/onLineAPIManual/functions/ErrorNumber_ns.html"><code class="function">ErrorNumber_ns</code></a></td></tr><tr><td><a class="netica" href="http://norsys.com/onLineAPIManual/functions/ErrorMessage_ns.html"><code class="function">ErrorMessage_ns</code></a></td></tr></table></dd><dt><span class="term"><code class="code">(netica:close-netica <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   :env :verbose)</code></span></dt><dd>Terminate the Netica session.
   Sets <code class="varname">netica:*env*</code> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
</dd><dt><span class="term"><code class="code">(netica:make-net <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :name
   :comment :title :env :verbose)</code></span></dt><dd>Call <a class="netica" href="http://norsys.com/onLineAPIManual/functions/NewNet_bn.html"><code class="function">NewNet_bn</code></a>,
   <a class="netica" href="http://norsys.com/onLineAPIManual/functions/SetNetTitle_bn.html"><code class="function">SetNetTitle_bn</code></a> and
   <a class="netica" href="http://norsys.com/onLineAPIManual/functions/SetNetComment_bn.html"><code class="function">SetNetComment_bn</code></a>.
</dd><dt><span class="term"><code class="code">(netica:net-info net <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :out)</code></span></dt><dd><p>Print some information about the net:</p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="netica" href="http://norsys.com/onLineAPIManual/functions/GetNetName_bn.html"><code class="function">GetNetName_bn</code></a></td></tr><tr><td><a class="netica" href="http://norsys.com/onLineAPIManual/functions/GetNetTitle_bn.html"><code class="function">GetNetTitle_bn</code></a></td></tr><tr><td><a class="netica" href="http://norsys.com/onLineAPIManual/functions/GetNetComment_bn.html"><code class="function">GetNetComment_bn</code></a></td></tr><tr><td><a class="netica" href="http://norsys.com/onLineAPIManual/functions/GetNetFileName_bn.html"><code class="function">GetNetFileName_bn</code></a></td></tr><tr><td><a class="netica" href="http://norsys.com/onLineAPIManual/functions/GetNetNodes_bn.html"><code class="function">GetNetNodes_bn</code></a></td></tr></table></dd><dt><span class="term"><code class="code">(netica:make-node <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   :name :net :kind :levels :states :num-states :title :comment :parents
   :cpt :x :y :env :verbose)</code></span></dt><dd>Call <a class="netica" href="http://norsys.com/onLineAPIManual/functions/NewNode_bn.html"><code class="function">NewNode_bn</code></a>
   with the given name and many other parameters.
</dd><dt><span class="term"><code class="code">(netica:node-info node
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :header :out)</code></span></dt><dd>Print some information about the node, preceded by
   the header.</dd><dt><span class="term"><code class="code">(netica:get-beliefs node
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :env :verbose)</code></span></dt><dd>Call <a class="netica" href="http://norsys.com/onLineAPIManual/functions/GetNodeBeliefs_bn.html"><code class="function">GetNodeBeliefs_bn</code></a>
   on the node and pretty-print the results when <code class="constant">:VERBOSE</code>
   is non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</dd><dt><span class="term"><code class="code">(netica:enter-finding net node
   state <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :env :verbose)</code></span></dt><dd>Call <a class="netica" href="http://norsys.com/onLineAPIManual/functions/EnterFinding_bn.html"><code class="function">EnterFinding_bn</code></a>
   using <a class="netica" href="http://norsys.com/onLineAPIManual/functions/GetNodeNamed_bn.html"><code class="function">GetNodeNamed_bn</code></a>
   and <a class="netica" href="http://norsys.com/onLineAPIManual/functions/GetStateNamed_bn.html"><code class="function">GetStateNamed_bn</code></a>.
</dd><dt><span class="term"><code class="code">(netica:save-net net <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   :file :env :verbose)</code></span></dt><dd>Call <a class="netica" href="http://norsys.com/onLineAPIManual/functions/WriteNet_bn.html"><code class="function">WriteNet_bn</code></a>.
</dd><dt><span class="term"><code class="code">(netica:read-net file <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   :env :verbose)</code></span></dt><dd>Call <a class="netica" href="http://norsys.com/onLineAPIManual/functions/ReadNet_bn.html"><code class="function">ReadNet_bn</code></a>.
</dd><dt><span class="term"><code class="code">(netica:with-open-dne-file (var
   file <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> opts) <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-4.html" target="_top"><code class="literal">&amp;BODY</code></a> body)</code></span></dt><dd>Call <a class="netica" href="http://norsys.com/onLineAPIManual/functions/NewFileStream_ns.html"><code class="function">NewFileStream_ns</code></a>,
   execute <em class="replaceable"><code>body</code></em>, then <a class="netica" href="http://norsys.com/onLineAPIManual/functions/DeleteStream_ns.html"><code class="function">DeleteStream_ns</code></a>
   - just like <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-open-stream.html" target="_top"><code class="function">WITH-OPEN-STREAM</code></a>.</dd><dt><span class="term"><code class="varname">netica:*verbose*</code></span></dt><dd>The log <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>; the default value for
   the <code class="constant">:VERBOSE</code> argument (initially set to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>).
</dd><dt><span class="term"><code class="varname">netica:*license*</code></span></dt><dd>The license key provided by
   <a class="ulink" href="http://norsys.com/" target="_top">Norsys</a>; the default value
   for the <code class="literal">:LICENSE</code> argument.
</dd><dt><span class="term"><code class="varname">netica:*env*</code></span></dt><dd>The Netica environment object; the default value
   for the <code class="literal">:ENV</code> argument.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="pcre"></a>33.15. Perl Compatible Regular Expressions</h2></div></div></div><p>This is an interface to <a class="ulink" href="http://www.pcre.org/" target="_top">Perl Compatible Regular Expressions</a>.</p><p>When this module is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a> contains the
 symbol <code class="constant">:PCRE</code>.</p><div class="variablelist"><a id="pcre-api"></a><p class="title"><strong>PCRE module API</strong></p><dl class="variablelist"><dt><a id="pcre-version"></a><span class="term"><code class="code">(PCRE:PCRE-VERSION)</code></span></dt><dd>Return version information as 4 values: descriptive
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>; 2 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_fixnum.html" target="_top"><code class="classname">FIXNUM</code></a>s: major and minor numbers; date <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>.
 </dd><dt><a id="pcre-config"></a><span class="term"><code class="code">(PCRE:PCRE-CONFIG <em class="replaceable"><code>type</code></em>)</code></span></dt><dd><p>Return some information about the PCRE build
    configuration.  <em class="replaceable"><code>type</code></em> is one of </p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="literal">:UTF8</code></td></tr><tr><td><code class="literal">:NEWLINE</code></td></tr><tr><td><code class="literal">:LINK-SIZE</code></td></tr><tr><td><code class="literal">:POSIX-MALLOC-THRESHOLD</code></td></tr><tr><td><code class="literal">:MATCH-LIMIT</code></td></tr><tr><td><code class="literal">:STACKRECURSE</code></td></tr><tr><td><code class="literal">:UNICODE-PROPERTIES </code></td></tr><tr><td><code class="literal">:MATCH-LIMIT-RECURSION</code></td></tr><tr><td><code class="literal">:BSR</code></td></tr></table></dd><dt><a id="pcre-compile"></a><span class="term"><code class="code">(PCRE:PCRE-COMPILE <em class="replaceable"><code>string</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :STUDY
    :IGNORE-CASE :MULTILINE :DOTALL :EXTENDED :ANCHORED :DOLLAR-ENDONLY
    :EXTRA :NOTBOL :NOTEOL :UNGREEDY :NOTEMPTY :NO-AUTO-CAPTURE)</code></span></dt><dd>Compile a pattern, optionally study it.
 </dd><dt><a id="pattern-info"></a><span class="term">
   <code class="code">(PCRE:PATTERN-INFO <em class="replaceable"><code>pattern</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> request)</code></span></dt><dd><p>Return some information about the <em class="replaceable"><code>pattern</code></em>,
    such as </p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="literal">:OPTIONS</code></td></tr><tr><td><code class="literal">:SIZE</code></td></tr><tr><td><code class="literal">:CAPTURECOUNT</code></td></tr><tr><td><code class="literal">:BACKREFMAX</code></td></tr><tr><td><code class="literal">:FIRSTBYTE</code></td></tr><tr><td><code class="literal">:FIRSTTABLE</code></td></tr><tr><td><code class="literal">:LASTLITERAL</code></td></tr><tr><td><code class="literal">:NAMEENTRYSIZE</code></td></tr><tr><td><code class="literal">:NAMECOUNT</code></td></tr><tr><td><code class="literal">:NAMETABLE</code></td></tr><tr><td><code class="literal">:STUDYSIZE</code></td></tr><tr><td><code class="literal">:OKPARTIAL</code></td></tr><tr><td><code class="literal">:JCHANGED</code></td></tr><tr><td><code class="literal">:HASCRORLF</code></td></tr><tr><td><code class="literal">:MINLENGTH</code></td></tr></table></dd><dt><a id="pcre-name-to-index"></a><span class="term"><code class="code">(PCRE:PCRE-NAME-TO-INDEX <em class="replaceable"><code>pattern</code></em> <em class="replaceable"><code>name</code></em>)</code></span></dt><dd>Convert the name of the sub-pattern to an index in
    the return vector.</dd><dt><a id="pcre-exec"></a><span class="term"><code class="code">(PCRE:PCRE-EXEC <em class="replaceable"><code>pattern</code></em> <em class="replaceable"><code>string</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    :WORK-SPACE :DFA :BOOLEAN :OFFSET :ANCHORED :NOTBOL :NOTEOL :NOTEMPTY
    :PARTIAL :DFA-SHORTEST :DFA-RESTART :FIRSTLINE :DUPNAMES :NEWLINE-CR
    :NEWLINE-LF :NEWLINE-CRLF :NEWLINE-ANY :NEWLINE-ANYCRLF :BSR-ANYCRLF
    :BSR-UNICODE :JAVASCRIPT-COMPAT :NO-START-OPTIMIZE :NO-START-OPTIMISE
    :PARTIAL-HARD :NOTEMPTY-ATSTART)</code></span></dt><dd><p class="simpara">Execute the compiled <em class="replaceable"><code>pattern</code></em> against the
    <em class="replaceable"><code>string</code></em> at the given <em class="replaceable"><code>offset</code></em> with the given options.
    Returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if no matches or a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_length.html" target="_top"><code class="function">LENGTH</code></a>
    <code class="literal">CAPTURECOUNT+1</code> of <span class="type">PCRE:MATCH</span> structures,
    unless <code class="literal">:BOOLEAN</code> was non-<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, in which case
    return <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> as an indicator of success, but do not allocate anything.
   </p><p class="simpara"><code class="constant">:DFA</code> argument determines
    whether <code class="function">pcre_dfa_exec</code> is used instead
    of <code class="function">pcre_exec</code> (PCRE v6 and better).</p><p class="simpara"><code class="constant">:WORK-SPACE</code> is only used
    for <code class="constant">:DFA</code> and defaults to 20.</p></dd><dt><a id="pcre-match-access"></a><span class="term"><code class="code">(PCRE:MATCH-START <em class="replaceable"><code>match</code></em>)</code><br /></span><span class="term"><code class="code">(PCRE:MATCH-END <em class="replaceable"><code>match</code></em>)</code></span></dt><dd>Return the start and end of the <em class="replaceable"><code>match</code></em>. <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a>-able.
 </dd><dt><a id="match-substring"></a><span class="term"><code class="code">(PCRE:MATCH-SUBSTRING <em class="replaceable"><code>match</code></em> <em class="replaceable"><code>string</code></em>)</code></span></dt><dd>Return the substring of <em class="replaceable"><code>string</code></em> bounded by <em class="replaceable"><code>match</code></em>.
 </dd><dt><a id="match-strings"></a><span class="term"><code class="code">(PCRE:MATCH-STRINGS return-vector <em class="replaceable"><code>string</code></em>)</code></span></dt><dd>Return all substrings for all matches found
    by <code class="function">PCRE:PCRE-EXEC</code>.
 </dd><dt><a id="match-string"></a><span class="term"><code class="code">(PCRE:MATCH-STRING return-vector which
    <em class="replaceable"><code>string</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>pattern</code></em>)</code></span></dt><dd>Return the substring that matches the given sub-pattern.
    If <em class="replaceable"><code>which</code></em> is a name of the sub-pattern (as
    opposed to its number), <em class="replaceable"><code>pattern</code></em> must be supplied.
 </dd><dt><a id="pcre-matcher"></a><span class="term"><code class="code">(PCRE:PCRE-MATCHER <em class="replaceable"><code>pattern</code></em>)</code></span></dt><dd>A valid value for <a class="link" href="#apropos" title="25.2.10. Functions APROPOS &amp; APROPOS-LIST"><code class="varname">CUSTOM:*APROPOS-MATCHER*</code></a>.
 </dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="zlib"></a>33.16. Interface to zlib</h2></div></div></div><p>This is an <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>-based interface to the <a class="ulink" href="http://zlib.net" target="_top">ZLIB</a>.</p><p>When this module is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a>
 contains the symbol <code class="constant">:ZLIB</code>.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">(ZLIB:Z-VERSION)</code></span></dt><dd>Return the string version of the underlying library.
</dd><dt><span class="term"><code class="code">(ZLIB:COMPRESS source <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> level)</code></span></dt><dd>Compress the <em class="replaceable"><code>source</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a>.
</dd><dt><span class="term"><code class="code">(ZLIB:UNCOMPRESS
   source destination-length)</code></span></dt><dd>Uncompress the <em class="replaceable"><code>source</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> (returned
   by <code class="function">ZLIB:COMPRESS</code>).
   <em class="replaceable"><code>destination-length</code></em> should be no less than
   the length of the uncompressed <em class="replaceable"><code>source</code></em>.
</dd><dt><span class="term"><code class="code">(ZLIB:COMPRESS-BOUND source-length)</code></span></dt><dd>Return the maximum length of the return value
   of <code class="function">ZLIB:COMPRESS</code>.</dd><dt><span class="term"><code class="code">(ZLIB:ERROR-STRING <em class="replaceable"><code>error-code</code></em>)</code></span></dt><dd>Return a descriptive string for the supplied <em class="replaceable"><code>error-code</code></em>.
</dd><dt><span class="term"><code class="classname">ZLIB:ZERROR</code></span></dt><dd>An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> sometimes <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed
   by <code class="function">ZLIB:COMPRESS</code>
   and <code class="function">ZLIB:UNCOMPRESS</code>.
   You can find the error code and the caller
   using <code class="function">ZLIB:ZERROR-ERRNO</code>
   and <code class="function">ZLIB:ZERROR-CALLER</code>.
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="rawsock"></a>33.17. Raw Socket Access</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#rawsock-intro">33.17.1. Introduction</a></span></dt><dt><span class="section"><a href="#rawsock-func">33.17.2. Single System Call Functions</a></span></dt><dt><span class="section"><a href="#rawsock-args">33.17.3. Common arguments</a></span></dt><dd><dl><dt><span class="section"><a href="#rawsock-plat-dep-constants">33.17.3.1. Platform-dependent Keywords</a></span></dt></dl></dd><dt><span class="section"><a href="#rawsock-return">33.17.4. Return Values</a></span></dt><dt><span class="section"><a href="#rawsock-not-implemented">33.17.5. Not Implemented</a></span></dt><dt><span class="section"><a href="#rawsock-errors">33.17.6. Errors</a></span></dt><dt><span class="section"><a href="#rawsock-high-level">33.17.7. High-Level Functions</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="rawsock-intro"></a>33.17.1. Introduction</h3></div></div></div><p>This is the raw socket interface, as described in
 <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_socket.h.html">&lt;<code class="filename">sys/socket.h</code>&gt;</a>.
Sockets are represented by their <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_fixnum.html" target="_top"><code class="classname">FIXNUM</code></a> <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a>s.</p><p>When this module is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a> contains the
 symbol <code class="constant">:RAWSOCK</code>.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="rawsock-use-sockets"></a>Try <code class="classname">SOCKET:SOCKET-STREAM</code> first!</h3><p>For most uses of sockets, the facilities described in
  <a class="xref" href="#socket" title="32.4. Socket Streams">Section 32.4, “Socket Streams”</a> are adequate and much more convenient than these.
  You are encouraged to consider <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-STREAM</code></a>s and ensure that they
  are not adequate for your purposes before you use raw sockets.
</p></div><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="rawsock-not-streams"></a>Do <span class="strong"><strong>not</strong></span> use <code class="function">EXT:MAKE-STREAM</code>!</h3><p>You can turn such a raw socket into a usual lisp <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>
  using <a class="link" href="#make-stream" title="21.9. Function EXT:MAKE-STREAM"><code class="function">EXT:MAKE-STREAM</code></a>, but you should be <span class="emphasis"><em>extremely</em></span>
  careful with such dubious actions!
  See the <a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-devel/">clisp-devel</a>
  <a class="ulink" href="http://sourceforge.net/mailarchive/message.php?msg_id=7203955" target="_top">mailing list archives</a> for more details.
  Note that <a class="link" href="#make-stream" title="21.9. Function EXT:MAKE-STREAM"><code class="function">EXT:MAKE-STREAM</code></a> will duplicate the <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_166">file descriptor</a> (using <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/dup.html"><code class="function">dup</code></a>),
  so you <span class="emphasis"><em>still</em></span> have to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_close.html" target="_top"><code class="function">CLOSE</code></a> the original raw socket.
</p></div><p>Test file <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/rawsock/test.tst"><code class="filename">modules/rawsock/test.tst</code></a>
 and the demos in <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/rawsock/demos/"><code class="filename">modules/rawsock/demos/</code></a>
 contain plenty of examples.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="rawsock-func"></a>33.17.2. Single System Call Functions</h3></div></div></div><p>We implement access to
 </p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/accept.html"><code class="function">accept</code></a>
    <em class="replaceable"><code>socket</code></em> <em class="replaceable"><code>address</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/bind.html"><code class="function">bind</code></a>
    <em class="replaceable"><code>socket</code></em> <em class="replaceable"><code>address</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/connect.html"><code class="function">connect</code></a>
    <em class="replaceable"><code>socket</code></em> <em class="replaceable"><code>address</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getaddrinfo.html"><code class="function">getaddrinfo</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
    node service protocol socktype family passive canonname numerichost
    numericserv v4mapped all addrconfig)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getnameinfo.html"><code class="function">getnameinfo</code></a> <em class="replaceable"><code>address</code></em>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> nofqdn numerichost namereqd numericserv numericscope
    dgram)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getpeername.html"><code class="function">getpeername</code></a>
    <em class="replaceable"><code>socket</code></em> <em class="replaceable"><code>address</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockname.html"><code class="function">getsockname</code></a>
    <em class="replaceable"><code>socket</code></em> <em class="replaceable"><code>address</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/htonl.html"><code class="function">htonl</code></a> <em class="replaceable"><code>n</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/htons.html"><code class="function">htons</code></a> <em class="replaceable"><code>n</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/ntohl.html"><code class="function">ntohl</code></a> <em class="replaceable"><code>n</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/ntohs.html"><code class="function">ntohs</code></a> <em class="replaceable"><code>n</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/recv.html"><code class="function">recv</code></a>
    <em class="replaceable"><code>socket</code></em> <em class="replaceable"><code>buffer</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> start end peek oob waitall)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/recvfrom.html"><code class="function">recvfrom</code></a> <em class="replaceable"><code>socket</code></em>
    <em class="replaceable"><code>buffer</code></em> <em class="replaceable"><code>address</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> start end peek oob waitall)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/recvmsg.html"><code class="function">recvmsg</code></a>
    <em class="replaceable"><code>socket</code></em> <em class="replaceable"><code>message</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> start end peek oob waitall)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/send.html"><code class="function">send</code></a>
    <em class="replaceable"><code>socket</code></em> <em class="replaceable"><code>buffer</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> start end oob eor)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/sendmsg.html"><code class="function">sendmsg</code></a>
    <em class="replaceable"><code>socket</code></em> <em class="replaceable"><code>message</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> start end oob eor)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/sendto.html"><code class="function">sendto</code></a>
    <em class="replaceable"><code>socket</code></em> <em class="replaceable"><code>buffer</code></em> <em class="replaceable"><code>address</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> start end oob eor)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/sockatmark.html"><code class="function">sockatmark</code></a>
    <em class="replaceable"><code>socket</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/socket.html"><code class="function">socket</code></a> <em class="replaceable"><code>domain</code></em> <em class="replaceable"><code>type</code></em> <em class="replaceable"><code>protocol</code></em>)</code></td></tr><tr><td><code class="code">(<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/socketpair.html"><code class="function">socketpair</code></a> <em class="replaceable"><code>domain</code></em> <em class="replaceable"><code>type</code></em> <em class="replaceable"><code>protocol</code></em>)</code></td></tr></table><p>using same-named lisp functions in package
 <strong class="package"><span class="quote">“<span class="quote">RAWSOCK</span>”</span></strong>.
 Additionally,</p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="code">(<code class="function">RAWSOCK:SOCK-CLOSE</code> <em class="replaceable"><code>socket</code></em>)</code>
   calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/close.html"><code class="function">close</code></a>.</td></tr><tr><td><code class="code">(<code class="function">RAWSOCK:SOCK-LISTEN</code> <em class="replaceable"><code>socket</code></em>
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> (<em class="replaceable"><code>backlog</code></em> SOMAXCONN))</code>
   calls <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/listen.html"><code class="function">listen</code></a>.</td></tr></table><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>When the OS does not provide <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/socketpair.html"><code class="function">socketpair</code></a>, it is emulated
  using <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/socket.html"><code class="function">socket</code></a> + <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/connect.html"><code class="function">connect</code></a> +
  <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/accept.html"><code class="function">accept</code></a>.</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="rawsock-args"></a>33.17.3. Common arguments</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#rawsock-plat-dep-constants">33.17.3.1. Platform-dependent Keywords</a></span></dt></dl></div><div class="variablelist"><a id="rawsock-args-list"></a><dl class="variablelist"><dt><span class="term"><span class="type">void*</span> <em class="replaceable"><code>buffer</code></em></span></dt><dd>A <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8))</code></span>.  The vector may be adjustable
   and have a fill pointer.  Whenever a function accepts a <em class="replaceable"><code>buffer</code></em>
   argument, it also accepts <code class="constant">:START</code> and <code class="constant">:END</code> keyword arguments
   with the usual meaning and defaults.  You do not have to supply the
   vector length because Lisp can determine it itself, but, if you want
   to, you can use <code class="constant">:END</code> argument for that.
</dd><dt><span class="term"><span class="type">int</span> <em class="replaceable"><code>socket</code></em></span></dt><dd>An <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> (returned by <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/socketpair.html"><code class="function">socketpair</code></a> or
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/socket.html"><code class="function">socket</code></a>).</dd><dt><span class="term"><span class="type">int</span> <em class="replaceable"><code>family</code></em><br /></span><span class="term"><span class="type">int</span> <em class="replaceable"><code>domain</code></em></span></dt><dd>A <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> (stands for <code class="constant">AF_UNSPEC</code>),
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>, or a platform-specific keyword, e.g.,
   <code class="constant">:INET</code> stands for <code class="constant">AF_INET</code>.
</dd><dt><span class="term"><span class="type">int</span> <em class="replaceable"><code>type</code></em></span></dt><dd>A <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> (stands for 0); <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>; or a
   platform-specific keyword, e.g.,
   <code class="constant">:DGRAM</code> stands for <code class="constant">SOCK_DGRAM</code>.
</dd><dt><span class="term"><span class="type">int</span> <em class="replaceable"><code>protocol</code></em></span></dt><dd>A <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> (stands for 0); <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>; a
   platform-specific keyword, e.g., <code class="constant">:ETH_P_ARP</code> stands
   for <code class="constant">ETH_P_ARP</code>, <code class="constant">:IPPROTO-ICMP</code>
   stands for <code class="constant">IPPROTO_ICMP</code>; or a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> (passed
   to <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getprotobyname.html"><code class="function">getprotobyname</code></a>).
</dd><dt><span class="term"><span class="type">int</span> <em class="replaceable"><code>flags</code></em></span></dt><dd>This <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> argument corresponds to keyword
   arguments to the Lisp functions.  E.g., <code class="function">rawsock:send</code>
   accepts <code class="constant">:OOB</code> and <code class="constant">:EOR</code> arguments,
   while <code class="function">rawsock:recv</code> accepts <code class="constant">:PEEK</code>,
   <code class="constant">:OOB</code> and <code class="constant">:WAITALL</code>.
</dd><dt><span class="term"><span class="type">struct sockaddr</span> <em class="replaceable"><code>address</code></em></span></dt><dd>A <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_structure-object.html" target="_top"><code class="classname">STRUCTURE-OBJECT</code></a> <span class="type">RAWSOCK:SOCKADDR</span>
   returned by
   <a class="link" href="#make-sockaddr"><code class="function">MAKE-SOCKADDR</code></a>.
</dd><dt><span class="term"><span class="type">struct msghdr</span> <em class="replaceable"><code>message</code></em></span></dt><dd><p>A <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_structure-object.html" target="_top"><code class="classname">STRUCTURE-OBJECT</code></a> <span class="type">RAWSOCK:MESSAGE</span>
   with the following slots:
   </p><div class="variablelist"><table border="0" class="variablelist"><colgroup><col align="left" valign="top" /><col /></colgroup><tbody><tr><td><p><span class="term">addr</span></p></td><td>
       a <a class="link" href="#make-sockaddr"><span class="type">SOCKADDR</span></a>.
    </td></tr><tr><td><p><span class="term">iovec</span></p></td><td>
       a <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8))</code></span>)</code></span>
       (<code class="constant">:START</code> and <code class="constant">:END</code> arguments are applied to this vector)
    </td></tr><tr><td><p><span class="term">control</span></p></td><td>
       a <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8))</code></span></td></tr><tr><td><p><span class="term">flags</span></p></td><td>
       a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a></td></tr></tbody></table></div></dd></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="rawsock-plat-dep-constants"></a>33.17.3.1. Platform-dependent Keywords</h4></div></div></div><p>One can extract the list of acceptable platform-dependent
 keywords for, e.g., socket domain, using the following code:
</p><pre class="programlisting">
 (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_block.html" target="_top"><code class="function">BLOCK</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>
   (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_handler-bind.html" target="_top"><code class="function">HANDLER-BIND</code></a> ((<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_type-error.html" target="_top"><code class="classname">TYPE-ERROR</code></a>
                    (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_lambda.html" target="_top"><code class="function">LAMBDA</code></a> (c)
                      (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> "~&amp;error: ~A~%" c)
                      (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_return.html" target="_top"><code class="function">RETURN</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDDR</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_firstcm_s_inthcm_tenth.html" target="_top"><code class="function">THIRD</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_type-erro_xpected-type.html" target="_top"><code class="function">TYPE-ERROR-EXPECTED-TYPE</code></a> c)))))))
     (rawsock:socket "bad" <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>)))
</pre></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="rawsock-return"></a>33.17.4. Return Values</h3></div></div></div><p>The return values of the functions described in section
 <a class="xref" href="#rawsock-func" title="33.17.2. Single System Call Functions">Section 33.17.2, “Single System Call Functions”</a> are derived from the return values of
 the underlying system call: if, say, the <em class="replaceable"><code>address</code></em> argument is modified
 by the system call, two values are returned (in addition to the
 possible values coming from the return value of the system call):
 the (modified) <em class="replaceable"><code>address</code></em> structure and its new size.
 If the system call fails, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="rawsock-not-implemented"></a>33.17.5. Not Implemented</h3></div></div></div><p>We do not interface to <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/select.html"><code class="function">select</code></a> or <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/poll.html"><code class="function">poll</code></a>
 in this module, they are already available through <a class="link" href="#so-status"><code class="function">SOCKET:SOCKET-STATUS</code></a>.</p><p>We do not interface to <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/shutdown.html"><code class="function">shutdown</code></a>
 in this module, it is already available through <a class="link" href="#sost-shut"><code class="function">SOCKET:SOCKET-STREAM-SHUTDOWN</code></a>.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="rawsock-errors"></a>33.17.6. Errors</h3></div></div></div><p>Errors in <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getaddrinfo.html"><code class="function">getaddrinfo</code></a>
 and <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getnameinfo.html"><code class="function">getnameinfo</code></a> are <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed
 as <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_condition.html" target="_top"><code class="classname">CONDITION</code></a>s of type <span class="type">RAWSOCK:EAI</span>
 using <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/gai_strerror.html"><code class="function">gai_strerror</code></a>.</p><p>Errors in other functions are reported as the usual OS errors
 (using <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/strerror.html"><code class="function">strerror</code></a>).</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="rawsock-high-level"></a>33.17.7. High-Level Functions</h3></div></div></div><div class="variablelist"><a id="rawsock-high-level-list"></a><p class="title"><strong>Functions that do not
  correspond to a single system call</strong></p><dl class="variablelist"><dt><a id="sock-read"></a><span class="term"><code class="code">(<code class="function">RAWSOCK:SOCK-READ</code>
   <em class="replaceable"><code>socket</code></em> <em class="replaceable"><code>buffer</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> start end)</code><br /></span><span class="term"><code class="code">(<code class="function">RAWSOCK:SOCK-WRITE</code>
   <em class="replaceable"><code>socket</code></em> <em class="replaceable"><code>buffer</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> start end)</code></span></dt><dd><p class="simpara">Call one of <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/read.html"><code class="function">read</code></a>/<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/readv.html"><code class="function">readv</code></a>
  or <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/write.html"><code class="function">write</code></a>/<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/writev.html"><code class="function">writev</code></a>
  (depending on whether <em class="replaceable"><code>buffer</code></em> is a <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8))</code></span> or
  a <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8))</code></span>)</code></span>).
  Return the number of bytes read or written.</p><p class="simpara">When <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/readv.html"><code class="function">readv</code></a> and
  <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/writev.html"><code class="function">writev</code></a> and not available, they are
  emulated by repeated calls to <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/read.html"><code class="function">read</code></a> and <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/write.html"><code class="function">write</code></a>.</p><p class="simpara">On <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> we have to use <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/recv.html"><code class="function">recv</code></a>
  instead of <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/read.html"><code class="function">read</code></a> and <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/send.html"><code class="function">send</code></a> instead of
  <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/write.html"><code class="function">write</code></a> because <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/read.html"><code class="function">read</code></a> and <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/write.html"><code class="function">write</code></a> do not work on sockets,
  only on regular files.</p></dd><dt><a id="rawsock-protocol"></a><span class="term"><code class="code">(RAWSOCK:PROTOCOL
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>protocol</code></em>)</code></span></dt><dd>Call <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getprotobyname.html"><code class="function">getprotobyname</code></a>
   when <em class="replaceable"><code>protocol</code></em> is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>,
   or call <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getprotobynumber.html"><code class="function">getprotobynumber</code></a> when
   <em class="replaceable"><code>protocol</code></em> is an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>.
   Return a <span class="type">RAWSOCK:PROTOCOL</span> structure object.
   When <em class="replaceable"><code>protocol</code></em> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, return a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of all known protocols using
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/setprotoent.html"><code class="function">setprotoent</code></a>,
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getprotoent.html"><code class="function">getprotoent</code></a>, and
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/endprotoent.html"><code class="function">endprotoent</code></a>.
</dd><dt><a id="rawsock-network"></a><span class="term"><code class="code">(RAWSOCK:NETWORK
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>network</code></em> <em class="replaceable"><code>type</code></em>)</code></span></dt><dd>Call <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getnetbyname.html"><code class="function">getnetbyname</code></a>
   when <em class="replaceable"><code>network</code></em> is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>,
   or call <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getnetbyaddr.html"><code class="function">getnetbyaddr</code></a> when
   <em class="replaceable"><code>network</code></em> is an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>.
   Return a <span class="type">RAWSOCK:NETWORK</span> structure object.
   When <em class="replaceable"><code>network</code></em> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, return a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of all known networks
   using <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/setnetent.html"><code class="function">setnetent</code></a>,
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getnetent.html"><code class="function">getnetent</code></a>, and
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/endnetent.html"><code class="function">endnetent</code></a>.
</dd><dt><a id="rawsock-if-name-index"></a><span class="term"><code class="code">(RAWSOCK:IF-NAME-INDEX
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>what</code></em>)</code></span></dt><dd>Call <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/if_nametoindex.html"><code class="function">if_nametoindex</code></a>
   when <em class="replaceable"><code>what</code></em> is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> and return an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>;
   or call <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/if_indextoname.html"><code class="function">if_indextoname</code></a> when
   <em class="replaceable"><code>what</code></em> is an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> and return a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>.
   When <em class="replaceable"><code>what</code></em> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, return an <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_a.html#association_list">association list</a> of
   pairs <span class="data"><code class="literal">(<em class="replaceable"><code>index</code></em> . <em class="replaceable"><code>name</code></em>)</code></span>
   using <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/if_nameindex.html"><code class="function">if_nameindex</code></a>.
</dd><dt><a id="rawsock-ifaddrs"></a><span class="term"><code class="code">(RAWSOCK:IFADDRS
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :FLAGS-OR :FLAGS-AND)</code></span></dt><dd>Call <a class="bsd" href="http://www.freebsd.org/cgi/man.cgi?query=getifaddrs"><code class="function">getifaddrs</code></a>
   and return a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> of <span class="type">ifaddrs</span> objects, optionally
   filtered using flags, e.g., <code class="code">(ifaddrs :flags-or '(<em class="replaceable"><code>k</code></em> <em class="replaceable"><code>l</code></em>)
    :flags-and '(<em class="replaceable"><code>m</code></em> <em class="replaceable"><code>n</code></em>))</code> will return a list of objects
   which have <span class="strong"><strong>both</strong></span> flags <em class="replaceable"><code>m</code></em> <span class="strong"><strong>and</strong></span> <em class="replaceable"><code>n</code></em> <span class="strong"><strong>and</strong></span> at least one of
   <em class="replaceable"><code>k</code></em> <span class="strong"><strong>or</strong></span> <em class="replaceable"><code>l</code></em> set.</dd><dt><a id="rawsock-sockopt"></a><span class="term"><code class="code">(RAWSOCK:SOCKET-OPTION
   <em class="replaceable"><code>socket</code></em> <em class="replaceable"><code>name</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :LEVEL)</code><br /></span><span class="term"><code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> (RAWSOCK:SOCKET-OPTION <em class="replaceable"><code>socket</code></em> <em class="replaceable"><code>name</code></em>
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> :LEVEL) <em class="replaceable"><code>value</code></em>)</code></span></dt><dd>Call <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/getsockopt.html"><code class="function">getsockopt</code></a>
   and <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/setsockopt.html"><code class="function">setsockopt</code></a>, returns and sets individual (for specific option
   <em class="replaceable"><code>name</code></em> and <em class="replaceable"><code>level</code></em>) and multiple (when <em class="replaceable"><code>name</code></em>
   is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and/or <em class="replaceable"><code>level</code></em> is <code class="constant">:ALL</code>) options.
   (See also <a class="link" href="#so-opt"><code class="function">SOCKET:SOCKET-OPTIONS</code></a>.)</dd><dt><a id="rawsock-convert-address"></a><span class="term"><code class="code">(<a class="link" href="#rawsock-convert-address"><code class="function">RAWSOCK:CONVERT-ADDRESS</code></a>
   <em class="replaceable"><code>family</code></em> <em class="replaceable"><code>address</code></em>)</code></span></dt><dd><p>Convert between <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a> and <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8))</code></span> <a class="rfc" href="http://www.ietf.org/rfc/rfc791.txt"><code><span class="command"><strong>IP</strong></span></code></a>
   <em class="replaceable"><code>address</code></em> representations using</p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/inet_addr.html"><code class="function">inet_addr</code></a></td><td><a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/inet_ntop.html"><code class="function">inet_ntop</code></a></td></tr><tr><td><a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/inet_ntoa.html"><code class="function">inet_ntoa</code></a></td><td><a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/inet_pton.html"><code class="function">inet_pton</code></a></td></tr></table><p>(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>s are also accepted for backward
 compatibility)</p></dd><dt><a id="make-sockaddr"></a><span class="term"><code class="code">(RAWSOCK:MAKE-SOCKADDR
   <em class="replaceable"><code>family</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> <em class="replaceable"><code>data</code></em>)</code></span></dt><dd><p class="simpara">Create a <span class="type">sockaddr</span> object.
   <em class="replaceable"><code>data</code></em> should be a sequence of <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8)</code></span> or an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>
   (meaning <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_make-list.html" target="_top"><code class="function">MAKE-LIST</code></a> <em class="replaceable"><code>data</code></em> :initial-element 0)</code>).
   When omitted, the standard platform-specific size is used.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>It is critical to use <em class="replaceable"><code>data</code></em> of the corrent size (usually
   <code class="code">sizeof(struct sockaddr)</code>, but may be something depending
   on the protocol to be used).</p></div></dd><dt><span class="term"><code class="code">(RAWSOCK:SOCKADDR-FAMILY <em class="replaceable"><code>address</code></em>)</code></span></dt><dd>Return the symbolic <em class="replaceable"><code>family</code></em> of the
   <span class="type">sockaddr</span> object.</dd><dt><span class="term"><code class="code">(RAWSOCK:SOCKADDR-DATA <em class="replaceable"><code>address</code></em>)</code></span></dt><dd><p class="simpara">Return a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_f.html#fresh">fresh</a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> displaced to the
   <em class="structfield"><code>data</code></em> field of the
   <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> <span class="type">struct sockaddr</span> object.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>Modifying this <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a>'s content will modify the
    <em class="replaceable"><code>address</code></em> argument data!</p></div></dd><dt><a id="rawsock-unix-socket"></a><span class="term"><code class="code">(RAWSOCK:OPEN-UNIX-SOCKET
   <em class="replaceable"><code>pathname</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> (<em class="replaceable"><code>type</code></em> <code class="constant">:STREAM</code>))</code></span></dt><dd>Open a <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> socket special file.
   Returns two values: <em class="replaceable"><code>socket</code></em> and <em class="replaceable"><code>address</code></em>.
</dd><dt><span class="term"><code class="code">(RAWSOCK:OPEN-UNIX-SOCKET-STREAM <em class="replaceable"><code>pathname</code></em>
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> <em class="replaceable"><code>options</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> (<em class="replaceable"><code>type</code></em> <code class="constant">:STREAM</code>)
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;ALLOW-OTHER-KEYS</code></a>)</code></span></dt><dd>Open a <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> socket special file.
   Returns two values: <em class="replaceable"><code>stream</code></em> and <em class="replaceable"><code>address</code></em>.  <em class="replaceable"><code>type</code></em> is passed
   to <code class="function">RAWSOCK:OPEN-UNIX-SOCKET</code>, other <em class="replaceable"><code>options</code></em>
   to <a class="link" href="#make-stream" title="21.9. Function EXT:MAKE-STREAM"><code class="function">EXT:MAKE-STREAM</code></a> (but see <a class="xref" href="#rawsock-not-streams" title="Do not use EXT:MAKE-STREAM!">Do <span class="strong"><strong>not</strong></span> use <code class="function">EXT:MAKE-STREAM</code>!</a>).
</dd><dt><span class="term"><code class="code">(RAWSOCK:IPCSUM <em class="replaceable"><code>buffer</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> start end)</code>
  - <a class="rfc" href="http://www.ietf.org/rfc/rfc791.txt"><code><span class="command"><strong>IP</strong></span></code></a><br /></span><span class="term"><code class="code">(RAWSOCK:ICMPCSUM <em class="replaceable"><code>buffer</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> start end)</code>
  - <a class="rfc" href="http://www.ietf.org/rfc/rfc792.txt"><code><span class="command"><strong>ICMP</strong></span></code></a><br /></span><span class="term"><code class="code">(RAWSOCK:TCPCSUM <em class="replaceable"><code>buffer</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> start end)</code>
  - <a class="rfc" href="http://www.ietf.org/rfc/rfc793.txt"><code><span class="command"><strong>TCP</strong></span></code></a><br /></span><span class="term"><code class="code">(RAWSOCK:UDPCSUM <em class="replaceable"><code>buffer</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> start end)</code>
  - <a class="rfc" href="http://www.ietf.org/rfc/rfc768.txt"><code><span class="command"><strong>UDP</strong></span></code></a></span></dt><dd><p class="simpara">Compute the appropriate protocol checksum and record
   it in the appropriate location.  <em class="replaceable"><code>buffer</code></em> is assumed to be a suitable
   ethernet frame for the protocol, with the appropriate header etc.</p><p class="simpara">Note that <em class="replaceable"><code>buffer</code></em> is an <span class="emphasis"><em>ethernet frame</em></span>,
   starting with 6 bytes of the destination MAC address, 6 bytes of the
   source MAC address, and 2 bytes specifying the next level protocol,
   (e.g., <code class="literal">#x0800</code> for <a class="rfc" href="http://www.ietf.org/rfc/rfc791.txt"><code><span class="command"><strong>IP</strong></span></code></a> and <code class="literal">#x0806</code>
   for <a class="rfc" href="http://www.ietf.org/rfc/rfc826.txt"><code><span class="command"><strong>ARP</strong></span></code></a>), i.e., the first 14 bytes of <em class="replaceable"><code>buffer</code></em> are ignored by these
   functions.</p><p class="simpara">A typical packet you send is both <a class="rfc" href="http://www.ietf.org/rfc/rfc791.txt"><code><span class="command"><strong>IP</strong></span></code></a> and <a class="rfc" href="http://www.ietf.org/rfc/rfc793.txt"><code><span class="command"><strong>TCP</strong></span></code></a> and thus
   has two checksums, so you would want to call <span class="emphasis"><em>two</em></span>
   functions.</p></dd><dt><span class="term"><code class="code">(RAWSOCK:CONFIGDEV <em class="replaceable"><code>socket</code></em>
   <em class="replaceable"><code>ifname</code></em> <em class="replaceable"><code>address</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>
   <em class="replaceable"><code>promisc</code></em>
   <em class="replaceable"><code>noarp</code></em>)</code></span></dt><dd>Set some socket options and <a class="rfc" href="http://www.ietf.org/rfc/rfc791.txt"><code><span class="command"><strong>IP</strong></span></code></a> <em class="replaceable"><code>address</code></em>
   with <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/ioctl.html"><code class="function">ioctl</code></a>.
</dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="fastcgi"></a>33.18. The <a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a> Interface</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#fcgi-overview">33.18.1. Overview of FastCGI</a></span></dt><dt><span class="section"><a href="#fcgi-functionality">33.18.2. Functions in Package <strong class="package"><span class="quote">“<span class="quote">FASTCGI</span>”</span></strong></a></span></dt><dt><span class="section"><a href="#fcgi-example">33.18.3. FastCGI Example</a></span></dt><dt><span class="section"><a href="#fcgi-build">33.18.4. Building and configuring the   FastCGI Interface</a></span></dt></dl></div><p>
The <a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a> module speeds up <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> CGI
scripts launched by a Web server.  Working with a
<a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a>-enabled Web server such as <a class="ulink" href="http://www.apache.org/" target="_top">Apache</a> with
<a class="ulink" href="https://httpd.apache.org/mod_fcgid/" target="_top">mod_fastcgi</a>, a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> program using the <a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a>
protocol will run many times faster than a conventional CGI program.
The performance improvements stem from the fact that the script's
process remains running across <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> requests, eliminating startup
overhead and allowing for caching of data structures and other resources.  This
is the same approach used is in other languages (e.g., <a class="ulink" href="http://perl.apache.org" target="_top">mod_perl</a> for Perl).  </p><p>When this module is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a> contains the
 symbol <code class="constant">:FASTCGI</code>.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="fcgi-overview"></a>33.18.1. Overview of <a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a></h3></div></div></div><p>
Traditional CGI programs work by doing input/output with the Web
server via the following channels:
</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
Examining environment variables; e.g., <code class="envar">HTTP_USER_AGENT</code> is the
variable set by the Web server to name the browser used
</li><li class="listitem">
Reading from standard input.  E.g., to get input data in a "method=POST" request
</li><li class="listitem">
Writing an <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> response document (usually "Content-type:
text/html") to the standard output, for eventual transmission
back to the browser client
</li><li class="listitem">
Writing error messages to the standard error, usually captured
by the Web server and logged in its log files.
</li></ol></div><p>
</p><p>
<a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a> involves replacing calls the standard routines to do
the above with calls in the <strong class="package"><span class="quote">“<span class="quote">FASTCGI</span>”</span></strong> package.  These calls will then
work exactly as before when the program is invoked as a CGI, but will
also work when invoked by a <a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a>-enabled Web server.
</p><p>
<a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a> programs persist across <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> requests, and thus incur
startup overhead costs only once.  For Lisp Web programs, this overhead
can be substantial: code must be
compiled and loaded, files and databases must be opened, etc.  Further,
because the program stays running from <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> request to <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> request,
it can cache information in memory such as database connections
or large in-memory data structures.

</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="fcgi-functionality"></a>33.18.2. Functions in Package <strong class="package"><span class="quote">“<span class="quote">FASTCGI</span>”</span></strong></h3></div></div></div><p>Access to
<a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a> is via these functions in package <strong class="package"><span class="quote">“<span class="quote">FASTCGI</span>”</span></strong>.

</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">(FASTCGI:IS-CGI)</code></span></dt><dd>
Returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> if the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> program has been launched as a traditional
CGI rather than in <a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a>.  In traditional CGI, program I/O is
via operating system environment variables and standard file streams.
Under <a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a>, I/O is done directly with the Web server via
the <a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a> protocol.
</dd><dt><span class="term">
<code class="code">(FASTCGI:ACCEPT)</code> <em class="replaceable"><code>cgi-forms</code></em>
<code class="code">(FASTCGI:FINISH)</code>
</span></dt><dd><p class="simpara">
In <a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a> mode, the program loops,
<code class="function">ACCEPT</code>ing to begin the execution of an <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a>
request, and <code class="function">FINISH</code>ing to signal that the script
is finished writing its response to the <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> request.  <code class="function">ACCEPT</code>
blocks until the next <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> request comes in, returning <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> if there is
a new request to handle, and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if no more <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> requests will
occur, usually because the Web server itself has terminated, in which
case the <a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a> server loop should also exit.
</p><p>
A typical <a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a> top-level server loop looks like:
</p><pre class="programlisting">
(do ()
    ((not (fastcgi:accept)))
  (run-my-script)
  (fastcgi:finish))
</pre><p>

</p></dd><dt><span class="term"><code class="code">(FASTCGI:GETENV
<em class="replaceable"><code>varname</code></em>)</code></span></dt><dd>
Use in place of <a class="link" href="#getenv" title="32.8. Operating System Environment"><code class="function">EXT:GETENV</code></a> to get the value of the environment variable
named <em class="replaceable"><code>varname</code></em>, which should be a string.
Unlike <a class="link" href="#getenv" title="32.8. Operating System Environment"><code class="function">EXT:GETENV</code></a>, which accesses the actual host operating system environment,
<code class="function">FASTCGI:GETENV</code> obtains its environment via
the Web server, over its FastCGI communications channel.
For more information, see the <a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a> Web site.
Returns <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> if <em class="replaceable"><code>varname</code></em> is not defined in
the operating system environment.  See <a class="ulink" href="http://www.cgi101.com/class/ch3/text.html" target="_top">here</a> for a
list of useful variables.  You must first have called
<code class="function">ACCEPT</code> and not yet have called
<code class="function">FINISH</code>.  </dd><dt><span class="term"><code class="code">(FASTCGI:WRITE-STDOUT
<em class="replaceable"><code>string</code></em>)</code></span></dt><dd>
Use in place of standard Lisp calls which print to standard output
(i.e., as part of the <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> response).
You must first have called <code class="function">ACCEPT</code> and not yet have
called <code class="function">FINISH</code>.
</dd><dt><span class="term"><code class="code">(FASTCGI:WRITE-STDERR
<em class="replaceable"><code>string</code></em>)</code></span></dt><dd>
Use in place of standard Lisp calls which print to
standard error. Rather than being part of
the <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> response, data written to standard error are usually
collected by the Web server in its error log.  This is useful
for diagnostic purposes.
</dd><dt><span class="term"><code class="code">(FASTCGI:SLURP-STDIN)</code></span></dt><dd>
Reads in the entirety of standard input and returns it as a string.
This is usually done for <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> requests with
<code class="literal">METHOD="post"</code>, when the data are passed to the CGI
script via standard input rather than via the environment variable
<code class="envar">QUERY_STRING</code>.  There is no way to read standard input
in pieces, which could be a problem, say, for <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> uploads of very large files.
</dd><dt><span class="term"><code class="code">(FASTCGI:OUT
<em class="replaceable"><code>tree</code></em>)</code></span></dt><dd>
Like <code class="function">WRITE-STDOUT</code>, except that
<em class="replaceable"><code>tree</code></em>
may be an arbitrarily nested list structure containing (at the leaves)
numbers and strings.  For example,
<code class="literal">(FASTCGI:OUT '("foo" (" " 10 " " 20)))</code>
will write the string <code class="literal">"foo 10 20"</code>.  This function
is useful when building strings in memory for display.
</dd></dl></div><p>

</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="fcgi-example"></a>33.18.3. <a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a> Example</h3></div></div></div><p>

Below is a simple example CGI script using <a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a>.

</p><pre class="programlisting">
#!/usr/local/bin/clisp -q -K full

(do ((count 1 (1+ count)))
    ((not (fastcgi:accept)) nil)
  (fastcgi:out "Content-type: text/plain" #\Newline #\Newline)
  (fastcgi:out
   "I am running in mode: " (if (fastcgi:is-cgi) "CGI" "FastCGI") #\Newline
   "This is execution no.: " count #\Newline
   "The browser string is '" (fastcgi:getenv "HTTP_USER_AGENT") "'" #\Newline)
  (fastcgi:finish))
</pre><p>

</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="fcgi-build"></a>33.18.4. Building and configuring the
  <a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a> Interface</h3></div></div></div><p>
It is necessary to download the <a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a> developers' kit, build it,
and install it, before building <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> with <a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a> support.
You also need to upgrade your Web server to speak the <a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a>
protocol.  For <a class="ulink" href="http://www.apache.org/" target="_top">Apache</a> this means building in <a class="ulink" href="https://httpd.apache.org/mod_fcgid/" target="_top">mod_fastcgi</a>, either statically
or dynamically, and then adding a line to your <a class="ulink" href="http://www.apache.org/" target="_top">Apache</a> config like:
</p><pre class="programlisting">
     Addhandler fastcgi-script .fcgi
</pre><p>
After that, you can convert <code class="filename">foo.cgi</code> by linking it
to a script names <code class="filename">foo.fcgi</code>.  Since a <a class="ulink" href="https://fastcgi-archives.github.io/" target="_top">FastCGI</a>
script is also a valid CGI script, it can be run unmodified in either
mode.
</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="dbus"></a>33.19. Interface to D-Bus</h2></div></div></div><p>This is an <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>-based interface to the <a class="ulink" href="http://www.freedesktop.org/wiki/Software/dbus" target="_top">D-Bus</a> message bus
 system, a simple way for applications to talk to one another.</p><p>The package <strong class="package"><span class="quote">“<span class="quote">DBUS</span>”</span></strong> is <a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-SENSITIVE</code></a>,
 e.g., you would write <code class="code">(dbus:dbus_error_init ...)</code>
 when you need to call the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> function
 <code class="function">dbus_error_init</code>.</p><p>When this module is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a>
 contains the symbol <code class="constant">:D-BUS</code>.</p><p>All public <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> functions are available as <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><code class="classname">FFI:FOREIGN-FUNCTION</code></a>s,
 defined in <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/dbus/dbus.lisp"><code class="filename">modules/dbus/dbus.lisp</code></a>.</p><p>See <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/dbus/test.tst"><code class="filename">modules/dbus/test.tst</code></a>
 for sample usage.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="gtk"></a>33.20. GTK Interface</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#gtk-hi">33.20.1. High-level functions</a></span></dt></dl></div><p>This is an <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>-based interface to <a class="ulink" href="http://www.gtk.org" target="_top">GTK+</a> version 2.</p><p>The package <strong class="package"><span class="quote">“<span class="quote">GTK</span>”</span></strong>
 is <a class="link" href="#package-case" title="11.5. Package Case-Sensitivity"><code class="constant">:CASE-SENSITIVE</code></a>.</p><p>When this module is present, <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a>
 contains the symbol <code class="constant">:GTK</code>.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="gtk-hi"></a>33.20.1. High-level functions</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">(glade-load <em class="replaceable"><code>filename</code></em>)</code></span></dt><dd>Load and connect the UI described in the
    <a class="ulink" href="http://glade.gnome.org/" target="_top">Glade</a>-generated file <em class="replaceable"><code>filename</code></em>.</dd><dt><span class="term"><code class="code">(run-glade-file <em class="replaceable"><code>filename</code></em> <em class="replaceable"><code>name</code></em>)</code></span></dt><dd>Run the widget <em class="replaceable"><code>name</code></em> described in the
    <a class="ulink" href="http://glade.gnome.org/" target="_top">Glade</a>-generated file <em class="replaceable"><code>filename</code></em>.</dd><dt><span class="term"><code class="code">(gui <em class="replaceable"><code>filename</code></em>)</code></span></dt><dd>Run the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> demo GUI described in the
    <a class="ulink" href="http://glade.gnome.org/" target="_top">Glade</a>-generated file <em class="replaceable"><code>filename</code></em>, normally a variation
    of <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/gtk2/ui.glade"><code class="filename">modules/gtk2/ui.glade</code></a>.
 </dd></dl></div></div></div></div></div><div class="part"><div class="titlepage"><div><div><h1 class="title"><a id="internals"></a>Part IV. Internals of the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> Implementation</h1></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="chapter"><a href="#source-files">34. The source files of <span class="command"><strong>CLISP</strong></span></a></span></dt><dd><dl><dt><span class="section"><a href="#src-file-types">34.1. File Types</a></span></dt><dt><span class="section"><a href="#src-preprocessing">34.2. Source Pre-Processing</a></span></dt><dt><span class="section"><a href="#src-files">34.3. Files</a></span></dt><dd><dl><dt><span class="section"><a href="#src-unpreproc-C">34.3.1. Unpreprocessed <span class="command"><strong>C</strong></span> code</a></span></dt><dt><span class="section"><a href="#src-asm-misc">34.3.2. Other assembly language stuff</a></span></dt><dt><span class="section"><a href="#src-lisp">34.3.3. Lisp source files</a></span></dt><dt><span class="section"><a href="#src-ext-mod">34.3.4. External Modules</a></span></dt><dt><span class="section"><a href="#src-doc">34.3.5. Documentation</a></span></dt><dt><span class="section"><a href="#src-i18n">34.3.6. Internationalization</a></span></dt><dt><span class="section"><a href="#src-conf-unix">34.3.7. Automatic configuration on <span class="strong"><strong>UNIX</strong></span> and <span class="platform">MinGW</span></a></span></dt><dt><span class="section"><a href="#src-external">34.3.8. Externally maintained files</a></span></dt></dl></dd></dl></dd><dt><span class="chapter"><a href="#gc">35. Overview of <span class="command"><strong>CLISP</strong></span>'s Garbage Collection</a></span></dt><dd><dl><dt><span class="section"><a href="#internals-intro">35.1. Introduction</a></span></dt><dt><span class="section"><a href="#lisp-obj-in-c">35.2. Lisp objects in <span class="command"><strong>CLISP</strong></span></a></span></dt><dt><span class="section"><a href="#typecodes">35.3. Object Pointer Representations</a></span></dt><dt><span class="section"><a href="#memory-models">35.4. Memory Models</a></span></dt><dt><span class="section"><a href="#gc-safety">35.5. The burden of garbage-collection upon the rest of <span class="command"><strong>CLISP</strong></span></a></span></dt><dd><dl><dt><span class="section"><a href="#gc-moves-data">35.5.1. Lisp <span class="type">object</span> invalidation</a></span></dt><dt><span class="section"><a href="#gc-lisp-in-C">35.5.2. Managing Lisp <span class="type">object</span>s in <span class="command"><strong>C</strong></span></a></span></dt><dt><span class="section"><a href="#gc-alloccount">35.5.3. Run-time GC-safety checks</a></span></dt><dt><span class="section"><a href="#gc-mem-prot">35.5.4. Memory protection</a></span></dt></dl></dd><dt><span class="section"><a href="#foreign-pointers">35.6. Foreign Pointers</a></span></dt><dt><span class="section"><a href="#nextgc-factor">35.7. Forcing or inhibiting Garbage Collections</a></span></dt><dt><span class="section"><a href="#gc-mt">35.8. Garbage Collection and Multithreading</a></span></dt></dl></dd><dt><span class="chapter"><a href="#extend">36. Extending <span class="command"><strong>CLISP</strong></span> Core</a></span></dt><dd><dl><dt><span class="section"><a href="#add-fun">36.1. Adding a built-in function</a></span></dt><dt><span class="section"><a href="#add-var">36.2. Adding a built-in variable</a></span></dt><dt><span class="section"><a href="#recompile">36.3. Recompilation</a></span></dt></dl></dd><dt><span class="chapter"><a href="#bytecode">37. The <span class="command"><strong>CLISP</strong></span> bytecode specification</a></span></dt><dd><dl><dt><span class="section"><a href="#byte-intro">37.1. Introduction</a></span></dt><dt><span class="section"><a href="#vm">37.2. The virtual machine</a></span></dt><dt><span class="section"><a href="#comp-fun">37.3. The structure of compiled functions</a></span></dt><dt><span class="section"><a href="#instr-struct">37.4. The general structure of the instructions</a></span></dt><dt><span class="section"><a href="#instr-set">37.5. The instruction set</a></span></dt><dd><dl><dt><span class="section"><a href="#instr-const">37.5.1. Instructions for constants</a></span></dt><dt><span class="section"><a href="#instr-lex-var">37.5.2. Instructions for lexical variables</a></span></dt><dt><span class="section"><a href="#instr-dyn-var">37.5.3. Instructions for dynamic variables</a></span></dt><dt><span class="section"><a href="#instr-stack">37.5.4. Instructions for stack operations</a></span></dt><dt><span class="section"><a href="#instr-jump">37.5.5. Instructions for control flow, jumps</a></span></dt><dt><span class="section"><a href="#instr-env">37.5.6. Instructions for lexical environment,    creation of closures</a></span></dt><dt><span class="section"><a href="#instr-funcall">37.5.7. Instructions for function calls</a></span></dt><dt><span class="section"><a href="#instr-optkey">37.5.8. Instructions for optional   and keyword parameters</a></span></dt><dt><span class="section"><a href="#instr-mulval">37.5.9. Instructions for multiple values</a></span></dt><dt><span class="section"><a href="#instr-block">37.5.10. Instructions for    <code class="function">BLOCK</code> and <code class="function">RETURN-FROM</code></a></span></dt><dt><span class="section"><a href="#instr-tagbody">37.5.11. Instructions for <code class="function">TAGBODY</code> and <code class="function">GO</code></a></span></dt><dt><span class="section"><a href="#instr-catch">37.5.12. Instructions for <code class="function">CATCH</code> and <code class="function">THROW</code></a></span></dt><dt><span class="section"><a href="#instr-unwind">37.5.13. Instructions for <code class="function">UNWIND-PROTECT</code></a></span></dt><dt><span class="section"><a href="#instr-handler">37.5.14. Instructions for <code class="function">HANDLER-BIND</code></a></span></dt><dt><span class="section"><a href="#instr-inline">37.5.15. Instructions for some inlined   functions</a></span></dt><dt><span class="section"><a href="#instr-combo">37.5.16. Combined instructions</a></span></dt><dt><span class="section"><a href="#instr-shortcut">37.5.17. Shortcut instructions</a></span></dt></dl></dd><dt><span class="section"><a href="#compiler-introspection">37.6. Examining compiled closures</a></span></dt><dt><span class="section"><a href="#bytecode-design">37.7. Bytecode Design</a></span></dt><dd><dl><dt><span class="section"><a href="#byte-when-add-q">37.7.1. When to add a new bytecode?</a></span></dt><dt><span class="section"><a href="#byte-jmptail-q">37.7.2. Why JMPTAIL?</a></span></dt></dl></dd></dl></dd></dl></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="source-files"></a>Chapter 34. The source files of <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a></h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#src-file-types">34.1. File Types</a></span></dt><dt><span class="section"><a href="#src-preprocessing">34.2. Source Pre-Processing</a></span></dt><dt><span class="section"><a href="#src-files">34.3. Files</a></span></dt><dd><dl><dt><span class="section"><a href="#src-unpreproc-C">34.3.1. Unpreprocessed <span class="command"><strong>C</strong></span> code</a></span></dt><dd><dl><dt><span class="section"><a href="#src-includes">34.3.1.1. Includes</a></span></dt><dt><span class="section"><a href="#src-modules">34.3.1.2. Internal <span class="command"><strong>C</strong></span> Modules</a></span></dt><dt><span class="section"><a href="#src-arith">34.3.1.3. Number system (arithmetic)</a></span></dt><dt><span class="section"><a href="#src-asm-sp">34.3.1.4. External routines for accessing the   stack, written in assembly language</a></span></dt></dl></dd><dt><span class="section"><a href="#src-asm-misc">34.3.2. Other assembly language stuff</a></span></dt><dt><span class="section"><a href="#src-lisp">34.3.3. Lisp source files</a></span></dt><dt><span class="section"><a href="#src-ext-mod">34.3.4. External Modules</a></span></dt><dt><span class="section"><a href="#src-doc">34.3.5. Documentation</a></span></dt><dt><span class="section"><a href="#src-i18n">34.3.6. Internationalization</a></span></dt><dt><span class="section"><a href="#src-conf-unix">34.3.7. Automatic configuration on <span class="strong"><strong>UNIX</strong></span> and <span class="platform">MinGW</span></a></span></dt><dt><span class="section"><a href="#src-external">34.3.8. Externally maintained files</a></span></dt></dl></dd></dl></div><p>For files in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> binary distributions,
 see <a href="clisp.html#files" class="olink">the section called “Files”</a>.</p><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="src-file-types"></a>34.1. File Types</h2></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="filename">#P"*.d"</code></span></dt><dd>The source files for unpreprocessed <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> code.
</dd><dt><span class="term"><code class="filename">#P".c"</code></span></dt><dd>The <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> code after
   <a class="link" href="#src-preprocessing" title="34.2. Source Pre-Processing">preprocessing</a>;
   also the result of compiling some <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> forms (see <a class="link" href="#ffi-extern-output"><code class="varname">FFI:*OUTPUT-C-FUNCTIONS*</code></a>).
</dd><dt><span class="term"><code class="filename">#P".lisp"</code></span></dt><dd>The source files for Lisp code.
</dd><dt><span class="term"><code class="filename">#P"*.fas"</code></span></dt><dd>Compiled lisp code (platform-independent <a href="impnotes.html#bytecode" class="olink">bytecode</a>s).
</dd><dt><span class="term"><a class="link" href="#lib-files" title="24.3.4. Interaction with COMPILE-FILE"><code class="filename">#P".lib"</code></a></span></dt><dd>Lisp <span class="quote">“<span class="quote">header</span>”</span>, produced by
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_compile-file.html" target="_top"><code class="function">COMPILE-FILE</code></a> and used by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_providecm_require.html" target="_top"><code class="function">REQUIRE</code></a></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="src-preprocessing"></a>34.2. Source Pre-Processing</h2></div></div></div><p><a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> sources are pre-processed with the following tools
   before being passed to the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> compiler:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/utils/comment5.c"><code class="filename">utils/comment5.c</code></a></span></dt><dd><p class="simpara">Convert <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/sh.html"><span class="command"><strong>/bin/sh</strong></span></a>-style comments (lines starting
  with <code class="literal">"# "</code>) to <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>-style comments
  (<code class="literal">/**/</code>).</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>The use of <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/sh.html"><span class="command"><strong>/bin/sh</strong></span></a>-style comments is deprecated.</p></div></dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/utils/varbrace.c"><code class="filename">utils/varbrace.c</code></a></span></dt><dd>Add braces to <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> source code, so that variable
  declarations (introduced with the pseudo-keyword <code class="literal">var</code>)
  can be used within blocks, like in <span class="command"><strong>C++</strong></span>
  and <span class="command"><strong>C99</strong></span>.</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/utils/ccpaux.c"><code class="filename">utils/ccpaux.c</code></a></span></dt><dd>When <a class="ulink" href="http://gcc.gnu.org/onlinedocs/cpp/" target="_top"><span class="command"><strong>cpp</strong></span></a> cannot handle indented directives, remove
  the indentation.</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/utils/gctrigger.c"><code class="filename">utils/gctrigger.c</code></a></span></dt><dd>Add <code class="function">GCTRIGGER</code> statements at the
  head of function bodies (for functions marked with
  the <code class="literal">maygc</code> pseudo-keyword).
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/utils/deema.c"><code class="filename">utils/deema.c</code></a></span></dt><dd>When <a class="ulink" href="http://gcc.gnu.org/onlinedocs/cpp/" target="_top"><span class="command"><strong>cpp</strong></span></a> cannot handle empty macro arguments,
  insert <code class="literal">_EMA_</code> instead.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/utils/ccmp2c.c"><code class="filename">utils/ccmp2c.c</code></a></span></dt><dd>For the <span class="module"><a href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/clx/new-clx/"><code class="filename">clx/new-clx</code></a></span> module only.
  Allows <a class="ulink" href="http://gcc.gnu.org/onlinedocs/cpp/" target="_top"><span class="command"><strong>cpp</strong></span></a>-style preprocessing <span class="strong"><strong>before</strong></span> <a class="link" href="#modprep-file"><span class="command"><strong>modprep</strong></span></a> processing.
  Should be merged into <a class="link" href="#modprep-file"><span class="command"><strong>modprep</strong></span></a> eventually.
</dd><dt><a id="modprep-file"></a><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/utils/modprep.lisp"><code class="filename">utils/modprep.lisp</code></a></span></dt><dd>For some modules only, see <a class="xref" href="#modprep" title="32.2.7.1. Modprep">Section 32.2.7.1, “Modprep”</a>.
</dd><dt><a id="utils-unicode"></a><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/utils/unicode/"><code class="filename">utils/unicode/</code></a></span></dt><dd><p>Generate NLS files in
   <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/"><code class="filename">src/</code></a>.
   </p><div class="variablelist"><dl class="variablelist"><dt><span class="term">
      <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/utils/unicode/UnicodeDataFull.txt"><code class="filename">utils/unicode/UnicodeDataFull.txt</code></a>
     </span></dt><dd>Character descriptions from <a class="ulink" href="http://www.unicode.org" target="_top">Unicode</a> <a class="ulink" href="http://www.unicode.org/unicode/reports/tr28/" target="_top">3.2</a>;
       used by <a href="impnotes.html#describe" class="olink"><code class="function">DESCRIBE</code></a> and installed in <code class="filename">data/</code>
       under <a href="clisp.html#opt-libdir" class="olink"><code class="varname">CUSTOM:*LIB-DIRECTORY*</code></a>.</dd></dl></div></dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="src-files"></a>34.3. Files</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#src-unpreproc-C">34.3.1. Unpreprocessed <span class="command"><strong>C</strong></span> code</a></span></dt><dd><dl><dt><span class="section"><a href="#src-includes">34.3.1.1. Includes</a></span></dt><dt><span class="section"><a href="#src-modules">34.3.1.2. Internal <span class="command"><strong>C</strong></span> Modules</a></span></dt><dt><span class="section"><a href="#src-arith">34.3.1.3. Number system (arithmetic)</a></span></dt><dd><dl><dt><span class="section"><a href="#src-ari-asm">34.3.1.3.1. External routines for the arithmetic   system, written in assembly language</a></span></dt></dl></dd><dt><span class="section"><a href="#src-asm-sp">34.3.1.4. External routines for accessing the   stack, written in assembly language</a></span></dt></dl></dd><dt><span class="section"><a href="#src-asm-misc">34.3.2. Other assembly language stuff</a></span></dt><dt><span class="section"><a href="#src-lisp">34.3.3. Lisp source files</a></span></dt><dt><span class="section"><a href="#src-ext-mod">34.3.4. External Modules</a></span></dt><dt><span class="section"><a href="#src-doc">34.3.5. Documentation</a></span></dt><dt><span class="section"><a href="#src-i18n">34.3.6. Internationalization</a></span></dt><dt><span class="section"><a href="#src-conf-unix">34.3.7. Automatic configuration on <span class="strong"><strong>UNIX</strong></span> and <span class="platform">MinGW</span></a></span></dt><dt><span class="section"><a href="#src-external">34.3.8. Externally maintained files</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="src-unpreproc-C"></a>34.3.1. Unpreprocessed <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> code</h3></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#src-includes">34.3.1.1. Includes</a></span></dt><dt><span class="section"><a href="#src-modules">34.3.1.2. Internal <span class="command"><strong>C</strong></span> Modules</a></span></dt><dt><span class="section"><a href="#src-arith">34.3.1.3. Number system (arithmetic)</a></span></dt><dd><dl><dt><span class="section"><a href="#src-ari-asm">34.3.1.3.1. External routines for the arithmetic   system, written in assembly language</a></span></dt></dl></dd><dt><span class="section"><a href="#src-asm-sp">34.3.1.4. External routines for accessing the   stack, written in assembly language</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="src-includes"></a>34.3.1.1. Includes</h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/lispbibl.d"><code class="filename">src/lispbibl.d</code></a></span></dt><dd>main include file</dd><dt><a id="fsubr-d"></a><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/fsubr.d"><code class="filename">src/fsubr.d</code></a></span></dt><dd>list of all built-in special forms
</dd><dt><a id="subr-d"></a><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/subr.d"><code class="filename">src/subr.d</code></a></span></dt><dd>list of all built-in functions
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/pseudofun.d"><code class="filename">src/pseudofun.d</code></a></span></dt><dd>list of all <span class="quote">“<span class="quote">pseudo functions</span>”</span>
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/constpack.d"><code class="filename">src/constpack.d</code></a></span></dt><dd>list of packages accessed by <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> code
</dd><dt><a id="constsym-d"></a><span class="term">
  <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/constsym.d"><code class="filename">src/constsym.d</code></a></span></dt><dd>list of symbols accessed by <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> code
</dd><dt><a id="constobj-d"></a><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/constobj.d"><code class="filename">src/constobj.d</code></a></span></dt><dd>list of miscellaneous objects accessed by <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> code
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/unix.d"><code class="filename">src/unix.d</code></a></span></dt><dd>include file for the <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> implementations
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/win32.d"><code class="filename">src/win32.d</code></a></span></dt><dd>include file for the <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> based versions
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/xthread.d"><code class="filename">src/xthread.d</code></a></span></dt><dd>include file for thread support
</dd><dt><span class="term"><code class="filename">build/modules.h</code></span></dt><dd>list of foreign <a href="impnotes.html#modules" class="olink">module</a>s, generated at build time
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="src-modules"></a>34.3.1.2. Internal <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> Modules</h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><a id="spvw-d"></a><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/spvw.d"><code class="filename">src/spvw.d</code></a></span></dt><dd><p>Memory management (<a href="impnotes.html#gc" class="olink">garbage-collect</a>ion), startup; some OS interface.
   </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/avl.d"><code class="filename">src/avl.d</code></a></span></dt><dd>An implementation of AVL (Adelson-Velskii and
       Landis) trees.</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/sort.d"><code class="filename">src/sort.d</code></a></span></dt><dd>A sorting routine.</dd></dl></div></dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/spvwtabf.d"><code class="filename">src/spvwtabf.d</code></a></span></dt><dd>The table of built-in special operators and functions.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/spvwtabs.d"><code class="filename">src/spvwtabs.d</code></a></span></dt><dd>The table of all <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>s accessed by <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> code.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/spvwtabo.d"><code class="filename">src/spvwtabo.d</code></a></span></dt><dd>The table of miscellaneous objects accessed by
   <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> code.</dd><dt><a id="eval-d"></a><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/eval.d"><code class="filename">src/eval.d</code></a></span></dt><dd><p>Evaluator (form interpreter) and <a href="impnotes.html#bytecode" class="olink">bytecode</a> interpreter.
   </p><div class="variablelist"><dl class="variablelist"><dt><a id="bytecode-d"></a><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/bytecode.d"><code class="filename">src/bytecode.d</code></a></span></dt><dd>List of <a href="impnotes.html#bytecode" class="olink">bytecode</a>s.</dd><dt><a id="lightning-c"></a><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/lightning.c"><code class="filename">src/lightning.c</code></a></span></dt><dd>Just-in-time compiler using <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/lightning/" target="_top">lightning</a>.</dd></dl></div></dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/control.d"><code class="filename">src/control.d</code></a></span></dt><dd>Special operator interpreter.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/pathname.d"><code class="filename">src/pathname.d</code></a></span></dt><dd>Pathnames, file- and directory-related functions.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/stream.d"><code class="filename">src/stream.d</code></a></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s of all kinds: <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_file-stream.html" target="_top"><code class="classname">FILE-STREAM</code></a>s,
   <a class="link" href="#terminal" title="21.2. Terminal interaction">terminal</a> streams, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string-stream.html" target="_top"><code class="classname">STRING-STREAM</code></a>s
   etc.</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/socket.d"><code class="filename">src/socket.d</code></a></span></dt><dd>Opening <a class="link" href="#socket" title="32.4. Socket Streams">socket</a>s for <a class="rfc" href="http://www.ietf.org/rfc/rfc793.txt"><code><span class="command"><strong>TCP</strong></span></code></a>/<a class="rfc" href="http://www.ietf.org/rfc/rfc791.txt"><code><span class="command"><strong>IP</strong></span></code></a> and <a class="ulink" href="http://www.cliki.net/CLX" target="_top"><span class="command"><strong>CLX</strong></span></a>.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/io.d"><code class="filename">src/io.d</code></a></span></dt><dd>The lisp reader (parser) and printer (including
   pretty printer).</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/array.d"><code class="filename">src/array.d</code></a></span></dt><dd>Functions dealing with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_array.html" target="_top"><code class="classname">ARRAY</code></a>s and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a>s.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/hashtabl.d"><code class="filename">src/hashtabl.d</code></a></span></dt><dd>Functions dealing with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_hash-table.html" target="_top"><code class="classname">HASH-TABLE</code></a>s.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/list.d"><code class="filename">src/list.d</code></a></span></dt><dd>Functions dealing with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>s.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/package.d"><code class="filename">src/package.d</code></a></span></dt><dd>Functions dealing with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_package.html" target="_top"><code class="classname">PACKAGE</code></a>s.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/record.d"><code class="filename">src/record.d</code></a></span></dt><dd>Functions dealing with records (structures, closures, etc.)
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/sequence.d"><code class="filename">src/sequence.d</code></a></span></dt><dd>The generic <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_sequence.html" target="_top"><code class="classname">SEQUENCE</code></a> functions.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/funarg.d"><code class="filename">src/funarg.d</code></a></span></dt><dd>Functional arguments, like <code class="constant">:TEST</code> and <code class="constant">:KEY</code>.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/charstrg.d"><code class="filename">src/charstrg.d</code></a></span></dt><dd>Functions dealing with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>s and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>s.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/debug.d"><code class="filename">src/debug.d</code></a></span></dt><dd>The <a class="link" href="#debugger" title="25.2. Debugging Utilities sec_25-1-2">debugger</a> and the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-1.html">read-eval-print loop</a>.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/error.d"><code class="filename">src/error.d</code></a></span></dt><dd><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> handling and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ing.
   </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/errunix.d"><code class="filename">src/errunix.d</code></a></span></dt><dd><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>-specific error messages.
    </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/errwin32.d"><code class="filename">src/errwin32.d</code></a></span></dt><dd><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>-specific error messages.
    </dd></dl></div></dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/misc.d"><code class="filename">src/misc.d</code></a></span></dt><dd>Miscellaneous functions.</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/time.d"><code class="filename">src/time.d</code></a></span></dt><dd>Timing functions.</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/predtype.d"><code class="filename">src/predtype.d</code></a></span></dt><dd>Predicates, type tests.</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/symbol.d"><code class="filename">src/symbol.d</code></a></span></dt><dd>Functions dealing with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_symbol.html" target="_top"><code class="classname">SYMBOL</code></a>s.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/unixaux.d"><code class="filename">src/unixaux.d</code></a></span></dt><dd>Auxiliary functions (<a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> version only).
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/win32aux.d"><code class="filename">src/win32aux.d</code></a></span></dt><dd>Auxiliary functions (<a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> version only).
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/foreign.d"><code class="filename">src/foreign.d</code></a></span></dt><dd><a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> implementation.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/lisparit.d"><code class="filename">src/lisparit.d</code></a></span></dt><dd>Functions dealing with numbers (arithmetic), see
   <a class="xref" href="#src-arith" title="34.3.1.3. Number system (arithmetic)">Section 34.3.1.3, “Number system (arithmetic)”</a>.</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/noreadline.d"><code class="filename">src/noreadline.d</code></a></span></dt><dd>Dummy plug-in for the <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://tiswww.case.edu/php/chet/readline/readline.html" target="_top">readline</a> library.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/zthread.d"><code class="filename">src/zthread.d</code></a></span></dt><dd>MT implementation.</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="src-arith"></a>34.3.1.3. Number system (arithmetic)</h4></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#src-ari-asm">34.3.1.3.1. External routines for the arithmetic   system, written in assembly language</a></span></dt></dl></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/lisparit.d"><code class="filename">src/lisparit.d</code></a></span></dt><dd>initialization, input/output of numbers, lisp functions
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/aridecl.d"><code class="filename">src/aridecl.d</code></a></span></dt><dd>declarations</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/arilev0.d"><code class="filename">src/arilev0.d</code></a></span></dt><dd>arithmetic at the machine level
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/arilev1.d"><code class="filename">src/arilev1.d</code></a></span></dt><dd>digit sequences</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/arilev1c.d"><code class="filename">src/arilev1c.d</code></a></span></dt><dd>operations on digit sequences, written in <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/arilev1i.d"><code class="filename">src/arilev1i.d</code></a></span></dt><dd>operations on digit sequences, as inline functions
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/arilev1e.d"><code class="filename">src/arilev1e.d</code></a></span></dt><dd>operations on digit sequences, bindings to external
   routines</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/intelem.d"><code class="filename">src/intelem.d</code></a></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>s: elementary operations
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/intlog.d"><code class="filename">src/intlog.d</code></a></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>s: logical connectives
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/intplus.d"><code class="filename">src/intplus.d</code></a></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>s: addition and subtraction
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/intcomp.d"><code class="filename">src/intcomp.d</code></a></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>s: comparison
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/intbyte.d"><code class="filename">src/intbyte.d</code></a></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>s: byte operations <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_ldb.html" target="_top"><code class="function">LDB</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_dpb.html" target="_top"><code class="function">DPB</code></a>
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/intmal.d"><code class="filename">src/intmal.d</code></a></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>s: multiplication
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/intdiv.d"><code class="filename">src/intdiv.d</code></a></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>s: division
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/intgcd.d"><code class="filename">src/intgcd.d</code></a></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>s: <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_gcd.html" target="_top"><code class="function">GCD</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_lcm.html" target="_top"><code class="function">LCM</code></a>
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/int2adic.d"><code class="filename">src/int2adic.d</code></a></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>s: operations on 2-adic integers
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/intsqrt.d"><code class="filename">src/intsqrt.d</code></a></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a>s: square root, n-th root
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/intprint.d"><code class="filename">src/intprint.d</code></a></span></dt><dd>subroutines for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> output
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/intread.d"><code class="filename">src/intread.d</code></a></span></dt><dd>subroutines for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_integer.html" target="_top"><code class="classname">INTEGER</code></a> input
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/rational.d"><code class="filename">src/rational.d</code></a></span></dt><dd>rational numbers (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_ratio.html" target="_top"><code class="classname">RATIO</code></a>s)
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/sfloat.d"><code class="filename">src/sfloat.d</code></a></span></dt><dd>elementary operations for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SHORT-FLOAT</code></a>s
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/ffloat.d"><code class="filename">src/ffloat.d</code></a></span></dt><dd>elementary operations for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SINGLE-FLOAT</code></a>s
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/dfloat.d"><code class="filename">src/dfloat.d</code></a></span></dt><dd>elementary operations for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">DOUBLE-FLOAT</code></a>s
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/lfloat.d"><code class="filename">src/lfloat.d</code></a></span></dt><dd>elementary operations for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">LONG-FLOAT</code></a>s
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/flo_konv.d"><code class="filename">src/flo_konv.d</code></a></span></dt><dd>conversions between <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_float.html" target="_top"><code class="classname">FLOAT</code></a>s
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/flo_rest.d"><code class="filename">src/flo_rest.d</code></a></span></dt><dd>general <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_float.html" target="_top"><code class="classname">FLOAT</code></a> operations
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/realelem.d"><code class="filename">src/realelem.d</code></a></span></dt><dd>elementary functions for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_real.html" target="_top"><code class="classname">REAL</code></a> numbers
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/realrand.d"><code class="filename">src/realrand.d</code></a></span></dt><dd>random numbers
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/realtran.d"><code class="filename">src/realtran.d</code></a></span></dt><dd>transcendental functions for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_real.html" target="_top"><code class="classname">REAL</code></a> numbers
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/compelem.d"><code class="filename">src/compelem.d</code></a></span></dt><dd>elementary functions for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_complex.html" target="_top"><code class="classname">COMPLEX</code></a> numbers
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/comptran.d"><code class="filename">src/comptran.d</code></a></span></dt><dd>transcendental functions for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_complex.html" target="_top"><code class="classname">COMPLEX</code></a> numbers
</dd></dl></div><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="src-ari-asm"></a>34.3.1.3.1. External routines for the arithmetic
  system, written in assembly language</h5></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/arisparc.d"><code class="filename">src/arisparc.d</code></a></span></dt><dd>written in SPARC assembler
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/arisparc64.d"><code class="filename">src/arisparc64.d</code></a></span></dt><dd>written in 64-bit SPARC assembler
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/ari80386.d"><code class="filename">src/ari80386.d</code></a></span></dt><dd>written in i386/i486 assembler
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/arimips.d"><code class="filename">src/arimips.d</code></a></span></dt><dd>written in MIPS assembler
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/arimips64.d"><code class="filename">src/arimips64.d</code></a></span></dt><dd>written in 64-bit MIPS assembler
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/arihppa.d"><code class="filename">src/arihppa.d</code></a></span></dt><dd>written in HPPA-1.0 assembler
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/arivaxunix.d"><code class="filename">src/arivaxunix.d</code></a></span></dt><dd>written in VAX assembler, Unix assembler syntax
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/ariarm.d"><code class="filename">src/ariarm.d</code></a></span></dt><dd>written in ARM assembler
</dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="src-asm-sp"></a>34.3.1.4. External routines for accessing the
  stack, written in assembly language</h4></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/sp68000.d"><code class="filename">src/sp68000.d</code></a></span></dt><dd>written in 68000 assembler, MIT syntax
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/spsparc.d"><code class="filename">src/spsparc.d</code></a></span></dt><dd>written in SPARC assembler
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/spsparc64.d"><code class="filename">src/spsparc64.d</code></a></span></dt><dd>written in 64-bit SPARC assembler
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/sp80386.d"><code class="filename">src/sp80386.d</code></a></span></dt><dd>written in i386/i486 assembler
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/spmips.d"><code class="filename">src/spmips.d</code></a></span></dt><dd>written in MIPS assembler
</dd></dl></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="src-asm-misc"></a>34.3.2. Other assembly language stuff</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/asmi386.sh"><code class="filename">src/asmi386.sh</code></a></span></dt><dd>converts i386 assembler from MIT syntax to a macro syntax
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/asmi386.hh"><code class="filename">src/asmi386.hh</code></a></span></dt><dd>expands i386 assembler in macro syntax to either MIT
   or Intel syntax</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="src-lisp"></a>34.3.3. Lisp source files</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><a id="init-lisp"></a><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/init.lisp"><code class="filename">src/init.lisp</code></a></span></dt><dd>the first file to be loaded during bootstrapping,
 loads everything else</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/defseq.lisp"><code class="filename">src/defseq.lisp</code></a></span></dt><dd>defines the usual sequence types for the generic
   sequence functions</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/backquote.lisp"><code class="filename">src/backquote.lisp</code></a></span></dt><dd>implements the backquote read macro
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/defmacro.lisp"><code class="filename">src/defmacro.lisp</code></a></span></dt><dd>implements <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmacro.html" target="_top"><code class="function">DEFMACRO</code></a></dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/macros1.lisp"><code class="filename">src/macros1.lisp</code></a></span></dt><dd>the most important macros
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/macros2.lisp"><code class="filename">src/macros2.lisp</code></a></span></dt><dd>some other macros
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/defs1.lisp"><code class="filename">src/defs1.lisp</code></a></span></dt><dd>miscellaneous definitions
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/timezone.lisp"><code class="filename">src/timezone.lisp</code></a></span></dt><dd>site-dependent definition of time zone, except for
   <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> and <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>.</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/places.lisp"><code class="filename">src/places.lisp</code></a></span></dt><dd>macros using <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a>s, definitions of most standard
   and extensiion <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#place">place</a>s</dd><dt><a id="floatprint-lisp"></a><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/floatprint.lisp"><code class="filename">src/floatprint.lisp</code></a></span></dt><dd>defines <a class="link" href="#write-float-decimal" title="22.2. Printing Floats sec_22-1-3-1-3"><code class="function">SYS::WRITE-FLOAT-DECIMAL</code></a> for printing floating
   point numbers in base 10</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/type.lisp"><code class="filename">src/type.lisp</code></a></span></dt><dd>functions working with <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_t.html#type_specifier">type specifier</a>s: <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_typep.html" target="_top"><code class="function">TYPEP</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_subtypep.html" target="_top"><code class="function">SUBTYPEP</code></a></dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/defstruct.lisp"><code class="filename">src/defstruct.lisp</code></a></span></dt><dd>implements the macro <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defstruct.html" target="_top"><code class="function">DEFSTRUCT</code></a>
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/format.lisp"><code class="filename">src/format.lisp</code></a></span></dt><dd>implements the function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_format.html" target="_top"><code class="function">FORMAT</code></a>
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/room.lisp"><code class="filename">src/room.lisp</code></a></span></dt><dd>implements the function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_room.html" target="_top"><code class="function">ROOM</code></a>
   (see also <a class="xref" href="#room" title="25.3.1. Function ROOM">Section 25.3.1, “Function <code class="function">ROOM</code>”</a>)</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/savemem.lisp"><code class="filename">src/savemem.lisp</code></a></span></dt><dd>see <a class="xref" href="#image" title="31.2. Saving an Image">Section 31.2, “Saving an Image”</a>
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/xcharin.lisp"><code class="filename">src/xcharin.lisp</code></a> (optional)</span></dt><dd>implements extended character input for <a class="link" href="#with-kbd" title="21.2.2. Macro EXT:WITH-KEYBOARD"><code class="function">EXT:WITH-KEYBOARD</code></a>
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/keyboard.lisp"><code class="filename">src/keyboard.lisp</code></a> (optional)</span></dt><dd>implements the macro <a class="link" href="#with-kbd" title="21.2.2. Macro EXT:WITH-KEYBOARD"><code class="function">EXT:WITH-KEYBOARD</code></a>
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/runprog.lisp"><code class="filename">src/runprog.lisp</code></a></span></dt><dd>implements the functions <a class="link" href="#run-prog"><code class="function">EXT:RUN-PROGRAM</code></a>, <a class="link" href="#run-prog"><code class="function">EXT:RUN-SHELL-COMMAND</code></a> etc.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/query.lisp"><code class="filename">src/query.lisp</code></a></span></dt><dd>implements the functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_y-or-n-pcm_yes-or-no-p.html" target="_top"><code class="function">Y-OR-N-P</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_y-or-n-pcm_yes-or-no-p.html" target="_top"><code class="function">YES-OR-NO-P</code></a>
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/reploop.lisp"><code class="filename">src/reploop.lisp</code></a></span></dt><dd>support for the <a class="link" href="#debugger" title="25.2. Debugging Utilities sec_25-1-2">debugger</a> and the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-1.html">read-eval-print loop</a>
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/dribble.lisp"><code class="filename">src/dribble.lisp</code></a></span></dt><dd>implements the functions <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_dribble.html" target="_top"><code class="function">DRIBBLE</code></a> and
   <a class="link" href="#dribble" title="25.2.11. Function DRIBBLE"><code class="function">EXT:DRIBBLE-STREAM</code></a>
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/complete.lisp"><code class="filename">src/complete.lisp</code></a></span></dt><dd>implements completion, see <a class="xref" href="#terminal" title="21.2. Terminal interaction">Section 21.2, “Terminal interaction”</a>.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/describe.lisp"><code class="filename">src/describe.lisp</code></a></span></dt><dd>implements functions <a href="impnotes.html#describe" class="olink"><code class="function">DESCRIBE</code></a>, <a href="impnotes.html#apropos" class="olink"><code class="function">APROPOS</code></a>,
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_aproposcm_apropos-list.html" target="_top"><code class="function">APROPOS-LIST</code></a></dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/trace.lisp"><code class="filename">src/trace.lisp</code></a></span></dt><dd><a class="link" href="#trace" title="25.2.6. Macro TRACE">tracer</a>
</dd><dt><a id="macros3-lisp"></a><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/macros3.lisp"><code class="filename">src/macros3.lisp</code></a> (optional)</span></dt><dd>macros <a class="link" href="#letf" title="31.11.2. Macros EXT:LETF &amp; EXT:LETF*"><code class="function">EXT:LETF</code></a>, <a class="link" href="#letf" title="31.11.2. Macros EXT:LETF &amp; EXT:LETF*"><code class="function">EXT:LETF*</code></a>, <a class="link" href="#ethe" title="31.11.1. Macro EXT:ETHE"><code class="function">EXT:ETHE</code></a>, <a class="link" href="#with-collect" title="31.11.4. Macro EXT:WITH-COLLECT"><code class="function">EXT:WITH-COLLECT</code></a>,
   function <a class="link" href="#compiled-file-p" title="24.7. Function EXT:COMPILED-FILE-P [CLRFI-2]"><code class="function">EXT:COMPILED-FILE-P</code></a>.</dd><dt><a id="config-lisp"></a><span class="term"><code class="filename">build/config.lisp</code></span></dt><dd><p>site-dependent configuration, a user-modified
   copy of one of the following:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/cfgunix.lisp"><code class="filename">src/cfgunix.lisp</code></a></span></dt><dd>for <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a></dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/cfgwin32.lisp"><code class="filename">src/cfgwin32.lisp</code></a></span></dt><dd>for the <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>
    </dd></dl></div><p>
   See <a class="xref" href="#customize" title="31.12. Customizing CLISP behavior">Section 31.12, “Customizing <span class="command"><strong>CLISP</strong></span> behavior”</a>.</p></dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/compiler.lisp"><code class="filename">src/compiler.lisp</code></a></span></dt><dd>compiles Lisp code to <a href="impnotes.html#bytecode" class="olink">bytecode</a>
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/functions.lisp"><code class="filename">src/functions.lisp</code></a></span></dt><dd><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_function-_a-expression.html" target="_top"><code class="function">FUNCTION-LAMBDA-EXPRESSION</code></a> et al
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/disassem.lisp"><code class="filename">src/disassem.lisp</code></a></span></dt><dd>the function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_disassemble.html" target="_top"><code class="function">DISASSEMBLE</code></a>
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/defs2.lisp"><code class="filename">src/defs2.lisp</code></a></span></dt><dd>miscellaneous [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] definitions
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/loop.lisp"><code class="filename">src/loop.lisp</code></a></span></dt><dd>implements the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>]-compatible <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_loop.html" target="_top"><code class="function">LOOP</code></a> macro
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos.lisp"><code class="filename">src/clos.lisp</code></a></span></dt><dd><p>loads the various parts of the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a>:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-package.lisp"><code class="filename">src/clos-package.lisp</code></a></span></dt><dd>declares the imports and exports of the
     <a class="link" href="#classes" title="4.2. Classes sec_4-3"><strong class="package"><span class="quote">“<span class="quote">CLOS</span>”</span></strong></a> package</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-macros.lisp"><code class="filename">src/clos-macros.lisp</code></a></span></dt><dd>defines some internal macros used by the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a>
     implementation</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-class0.lisp"><code class="filename">src/clos-class0.lisp</code></a></span></dt><dd>defines the <code class="classname">class-version</code>
     structure</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-metaobject1.lisp"><code class="filename">src/clos-metaobject1.lisp</code></a></span></dt><dd>defines the <a class="link" href="#mop-metaobjects" title="29.2.1. Metaobjects"><code class="classname">CLOS:METAOBJECT</code></a> class
  </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-slotdef1.lisp"><code class="filename">src/clos-slotdef1.lisp</code></a></span></dt><dd>defines the <a class="link" href="#mop-sd" title="29.4. Slot Definitions"><code class="classname">CLOS:SLOT-DEFINITION</code></a> class and its
     subclasses</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-slotdef2.lisp"><code class="filename">src/clos-slotdef2.lisp</code></a></span></dt><dd>defines <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a> methods for
     <a class="link" href="#mop-sd" title="29.4. Slot Definitions"><code class="classname">CLOS:SLOT-DEFINITION</code></a> and its subclasses</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-slotdef3.lisp"><code class="filename">src/clos-slotdef3.lisp</code></a></span></dt><dd>defines the generic functions that can be used on
     <a class="link" href="#mop-sd" title="29.4. Slot Definitions"><code class="classname">CLOS:SLOT-DEFINITION</code></a> objects</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-stablehash1.lisp"><code class="filename">src/clos-stablehash1.lisp</code></a></span></dt><dd>defines the <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="classname">EXT:STANDARD-STABLEHASH</code></a> class
  </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-stablehash2.lisp"><code class="filename">src/clos-stablehash2.lisp</code></a></span></dt><dd>defines <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a> methods for
     <a class="link" href="#make-hash" title="18.2. Function MAKE-HASH-TABLE"><code class="classname">EXT:STANDARD-STABLEHASH</code></a></dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-specializer1.lisp"><code class="filename">src/clos-specializer1.lisp</code></a></span></dt><dd>defines the <a class="link" href="#mop-mo-spec" title="29.2.1.5. Specializers"><code class="classname">CLOS:SPECIALIZER</code></a> class and its subclasses
  </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-specializer2.lisp"><code class="filename">src/clos-specializer2.lisp</code></a></span></dt><dd>defines <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a> methods for
     <a class="link" href="#mop-mo-spec" title="29.2.1.5. Specializers"><code class="classname">CLOS:SPECIALIZER</code></a> and its subclasses</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-specializer3.lisp"><code class="filename">src/clos-specializer3.lisp</code></a></span></dt><dd>defines the generic functions that can be used on
     <a class="link" href="#mop-mo-spec" title="29.2.1.5. Specializers"><code class="classname">CLOS:SPECIALIZER</code></a> objects</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-class1.lisp"><code class="filename">src/clos-class1.lisp</code></a></span></dt><dd>defines the <code class="classname">potential-class</code>
     class and its subclasses</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-class2.lisp"><code class="filename">src/clos-class2.lisp</code></a></span></dt><dd>implements the mapping from class names to classes
  </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-class3.lisp"><code class="filename">src/clos-class3.lisp</code></a></span></dt><dd>implements the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defclass.html" target="_top"><code class="function">DEFCLASS</code></a> macro, class definition
     and class redefinition</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-class4.lisp"><code class="filename">src/clos-class4.lisp</code></a></span></dt><dd>defines <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a> methods
     for <code class="classname">potential-class</code> and its
     subclasses</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-class5.lisp"><code class="filename">src/clos-class5.lisp</code></a></span></dt><dd>implements the special logic of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_make-instance.html" target="_top"><code class="function">MAKE-INSTANCE</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a> etc.</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-class6.lisp"><code class="filename">src/clos-class6.lisp</code></a></span></dt><dd>defines the generic functions that can be used on
     <code class="classname">potential-class</code> objects
  </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-method1.lisp"><code class="filename">src/clos-method1.lisp</code></a></span></dt><dd>defines the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a> class and its subclasses
  </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-method2.lisp"><code class="filename">src/clos-method2.lisp</code></a></span></dt><dd>implements the bulk of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a>
  </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-method3.lisp"><code class="filename">src/clos-method3.lisp</code></a></span></dt><dd>defines the generic functions that can be used on
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method.html" target="_top"><code class="classname">METHOD</code></a> objects</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-method4.lisp"><code class="filename">src/clos-method4.lisp</code></a></span></dt><dd>makes generic functions on <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_standard-method.html" target="_top"><code class="classname">STANDARD-METHOD</code></a>
     objects extensible</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-methcomb1.lisp"><code class="filename">src/clos-methcomb1.lisp</code></a></span></dt><dd>defines the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method-combination.html" target="_top"><code class="classname">METHOD-COMBINATION</code></a> class
  </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-methcomb2.lisp"><code class="filename">src/clos-methcomb2.lisp</code></a></span></dt><dd>implements method combination (part 2 of generic
     function dispatch and execution) and the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_define-me_-combination.html" target="_top"><code class="function">DEFINE-METHOD-COMBINATION</code></a> macro
  </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-methcomb3.lisp"><code class="filename">src/clos-methcomb3.lisp</code></a></span></dt><dd>defines <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a> methods for
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method-combination.html" target="_top"><code class="classname">METHOD-COMBINATION</code></a></dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-methcomb4.lisp"><code class="filename">src/clos-methcomb4.lisp</code></a></span></dt><dd>makes generic functions on <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_method-combination.html" target="_top"><code class="classname">METHOD-COMBINATION</code></a>
     objects extensible</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-genfun1.lisp"><code class="filename">src/clos-genfun1.lisp</code></a></span></dt><dd>defines the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_generic-function.html" target="_top"><code class="classname">GENERIC-FUNCTION</code></a> class and its
     metaclass, superclass and subclasses</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-genfun2a.lisp"><code class="filename">src/clos-genfun2a.lisp</code></a></span></dt><dd>implements part 1 of generic function dispatch and
     execution</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-genfun2b.lisp"><code class="filename">src/clos-genfun2b.lisp</code></a></span></dt><dd>implements part 3 of generic function dispatch and
     execution</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-genfun3.lisp"><code class="filename">src/clos-genfun3.lisp</code></a></span></dt><dd>implements creation of generic function objects,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defmethod.html" target="_top"><code class="function">DEFMETHOD</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defgeneric.html" target="_top"><code class="function">DEFGENERIC</code></a></dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-genfun4.lisp"><code class="filename">src/clos-genfun4.lisp</code></a></span></dt><dd>defines <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_ini_ize-instance.html" target="_top"><code class="function">INITIALIZE-INSTANCE</code></a> methods for
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_generic-function.html" target="_top"><code class="classname">GENERIC-FUNCTION</code></a> and its subclasses</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-genfun5.lisp"><code class="filename">src/clos-genfun5.lisp</code></a></span></dt><dd>makes generic functions on <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_generic-function.html" target="_top"><code class="classname">GENERIC-FUNCTION</code></a>
     objects extensible</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-slots1.lisp"><code class="filename">src/clos-slots1.lisp</code></a></span></dt><dd>implements low-level slot access, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-slots.html" target="_top"><code class="function">WITH-SLOTS</code></a>,
     <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-accessors.html" target="_top"><code class="function">WITH-ACCESSORS</code></a></dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-slots2.lisp"><code class="filename">src/clos-slots2.lisp</code></a></span></dt><dd>defines the generic functions that deal with slot access
  </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-dependent.lisp"><code class="filename">src/clos-dependent.lisp</code></a></span></dt><dd>implements notification from metaobjects to
     dependent objects</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-print.lisp"><code class="filename">src/clos-print.lisp</code></a></span></dt><dd>implements the function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_print-object.html" target="_top"><code class="function">PRINT-OBJECT</code></a>
  </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clos-custom.lisp"><code class="filename">src/clos-custom.lisp</code></a></span></dt><dd>provides user customization of the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a>
  </dd></dl></div></dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/gray.lisp"><code class="filename">src/gray.lisp</code></a></span></dt><dd>implements <a class="ulink" href="http://www.nhplace.com/kent/CL/Issues/stream-definition-by-user.html" target="_top">STREAM-DEFINITION-BY-USER:GENERIC-FUNCTIONS</a>
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/fill-out.lisp"><code class="filename">src/fill-out.lisp</code></a></span></dt><dd>implements <a class="link" href="#fill-stream" title="30.8. Class EXT:FILL-STREAM"><code class="classname">EXT:FILL-STREAM</code></a>
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/disassem.lisp"><code class="filename">src/disassem.lisp</code></a></span></dt><dd>implements <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_disassemble.html" target="_top"><code class="function">DISASSEMBLE</code></a>
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/condition.lisp"><code class="filename">src/condition.lisp</code></a></span></dt><dd>implements the <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> Condition System (<a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-9.html"><span class="command"><strong>CLCS</strong></span></a>)
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/gstream.lisp"><code class="filename">src/gstream.lisp</code></a> (optional)</span></dt><dd>generic stream default methods,
   see <a class="xref" href="#gstream" title="31.6. Generic streams">Section 31.6, “Generic streams”</a></dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/foreign1.lisp"><code class="filename">src/foreign1.lisp</code></a></span></dt><dd><a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> implementation.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/screen.lisp"><code class="filename">src/screen.lisp</code></a></span></dt><dd>the screen access package, see <a class="xref" href="#screen" title="32.1. Random Screen Access">Section 32.1, “Random Screen Access”</a>
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/edit.lisp"><code class="filename">src/edit.lisp</code></a>
  (optional)</span></dt><dd>the screen editor (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_ed.html" target="_top"><code class="function">ED</code></a>), <a class="link" href="#uncompile" title="25.2.2. Function EXT:UNCOMPILE"><code class="function">EXT:UNCOMPILE</code></a>
</dd><dt><a id="inspect-lisp"></a><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/inspect.lisp"><code class="filename">src/inspect.lisp</code></a></span></dt><dd>implements <a class="link" href="#inspect" title="25.2.7. Function INSPECT"><code class="function">INSPECT</code></a> (tty and <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> frontends)
</dd><dt><a id="clhs-lisp"></a><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/clhs.lisp"><code class="filename">src/clhs.lisp</code></a></span></dt><dd>implements <a class="link" href="#open-http" title="31.11.9. Function EXT:OPEN-HTTP and macro EXT:WITH-HTTP-INPUT"><code class="function">EXT:OPEN-HTTP</code></a>, <a class="link" href="#browse-url" title="31.11.11. Function EXT:BROWSE-URL"><code class="function">EXT:BROWSE-URL</code></a>
</dd><dt><a id="exporting-lisp"></a><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/exporting.lisp"><code class="filename">src/exporting.lisp</code></a></span></dt><dd>Macros that export their definienda,
   see <a class="xref" href="#exporting" title="32.2.7.3. Exporting">Section 32.2.7.3, “Exporting”</a>.</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/threads.lisp"><code class="filename">src/threads.lisp</code></a></span></dt><dd>MT interface</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/german.lisp"><code class="filename">src/german.lisp</code></a><br /></span><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/french.lisp"><code class="filename">src/french.lisp</code></a><br /></span><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/spanish.lisp"><code class="filename">src/spanish.lisp</code></a><br /></span><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/russian.lisp"><code class="filename">src/russian.lisp</code></a><br /></span><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/danish.lisp"><code class="filename">src/danish.lisp</code></a><br /></span><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/dutch.lisp"><code class="filename">src/dutch.lisp</code></a></span></dt><dd><a class="link" href="#i18n" title="31.4. Internationalization of CLISP">i18n</a> user messages
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="src-ext-mod"></a>34.3.4. External Modules</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/"><code class="filename">modules/</code></a></span></dt><dd>individual external module sources
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="src-doc"></a>34.3.5. Documentation</h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><a id="src-news"></a><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/NEWS"><code class="filename">src/NEWS</code></a></span></dt><dd>the list of the user-visible changes
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/_README"><code class="filename">src/_README</code></a></span></dt><dd><p>master for the distribution's README</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/_README.en"><code class="filename">src/_README.en</code></a><br /></span><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/_README.de"><code class="filename">src/_README.de</code></a><br /></span><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/_README.es"><code class="filename">src/_README.es</code></a></span></dt><dd>translations of
       <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/_README"><code class="filename">src/_README</code></a>
    </dd></dl></div></dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/doc/clisp.xml.in"><code class="filename">doc/clisp.xml.in</code></a></span></dt><dd><a class="ulink" href="http://www.docbook.org/" target="_top">DocBook</a>/<a class="ulink" href="http://www.w3.org/XML/" target="_top">XML</a> sources for the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
   <a href="clisp.html#clisp" class="olink">manual page</a>
</dd><dt><span class="term"><code class="filename"><em class="replaceable"><code>build-dir</code></em>/clisp.1</code></span></dt><dd>the platform-specific
   <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/man.html"><span class="command"><strong>man</strong></span></a> manual page,
   generated from <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/doc/clisp.xml.in"><code class="filename">doc/clisp.xml.in</code></a>
   at <span class="emphasis"><em>build</em></span> time</dd><dt><span class="term"><code class="filename"><em class="replaceable"><code>build-dir</code></em>/clisp.html</code></span></dt><dd>the platform-specific <a class="ulink" href="http://www.w3.org/MarkUp/" target="_top">HTML</a> manual page,
   generated from <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/doc/clisp.xml.in"><code class="filename">doc/clisp.xml.in</code></a>
   at <span class="emphasis"><em>build</em></span> time</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/doc/impnotes.xml.in"><code class="filename">doc/impnotes.xml.in</code></a></span></dt><dd><p>the master <a class="ulink" href="http://www.docbook.org/" target="_top">DocBook</a>/<a class="ulink" href="http://www.w3.org/XML/" target="_top">XML</a> file for these
   implementation notes; includes the following files</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/doc/cl-ent.xml"><code class="filename">doc/cl-ent.xml</code></a></span></dt><dd><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>-independent general <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a>-related entities
    </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/doc/clhs-ent.xml"><code class="filename">doc/clhs-ent.xml</code></a></span></dt><dd>generated list of [<span class="citation"><a class="link" href="#CLHS" title="Common Lisp HyperSpec">Common Lisp HyperSpec</a></span>] entities
    </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/doc/impent.xml"><code class="filename">doc/impent.xml</code></a></span></dt><dd><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>-specific entities
    </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/doc/unix-ent.xml"><code class="filename">doc/unix-ent.xml</code></a></span></dt><dd><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a>-related entities
    </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/doc/mop-ent.xml"><code class="filename">doc/mop-ent.xml</code></a></span></dt><dd><a class="link" href="#mop-chap" title="Chapter 29. Meta-Object Protocol">Meta-Object Protocol</a>-related entities
    </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/doc/impbody.xml"><code class="filename">doc/impbody.xml</code></a></span></dt><dd>most of <a class="xref" href="#clhs-chapters" title="Part I. Chapters or the Common Lisp HyperSpec">Part I, “Chapters or the Common Lisp HyperSpec”</a>
    </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/doc/impissue.xml"><code class="filename">doc/impissue.xml</code></a></span></dt><dd><a class="xref" href="#issues" title="Chapter 28. X3J13 Issue Index [CLHS-ic]">Chapter 28, <em>X3J13 Issue Index    [CLHS-ic]</em></a>
    </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/doc/gray.xml"><code class="filename">doc/gray.xml</code></a></span></dt><dd><a class="xref" href="#gray" title="Chapter 30. Gray streams">Chapter 30, <em>Gray streams</em></a>
    </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/doc/mop.xml"><code class="filename">doc/mop.xml</code></a></span></dt><dd><a class="xref" href="#mop-chap" title="Chapter 29. Meta-Object Protocol">Chapter 29, <em>Meta-Object Protocol</em></a>
    </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/doc/impext.xml"><code class="filename">doc/impext.xml</code></a></span></dt><dd><a class="xref" href="#ext-p-indep" title="Chapter 31. Platform Independent Extensions">Chapter 31, <em>Platform Independent Extensions</em></a> and
       <a class="xref" href="#ext-platform" title="Chapter 32. Platform Specific Extensions">Chapter 32, <em>Platform Specific Extensions</em></a></dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/doc/impbyte.xml"><code class="filename">doc/impbyte.xml</code></a></span></dt><dd>this <a class="xref" href="#internals" title="Part IV. Internals of the CLISP Implementation">Part IV, “Internals of the <span class="command"><strong>CLISP</strong></span> Implementation”</a>
    </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/doc/faq.xml"><code class="filename">doc/faq.xml</code></a></span></dt><dd><a class="xref" href="#faq" title="Appendix A. Frequently Asked Questions (With Answers) about CLISP">Appendix A, <em>Frequently Asked Questions (With Answers)   about <span class="command"><strong>CLISP</strong></span></em></a>
    </dd><dt><span class="term"><code class="filename">modules/**/*.xml</code></span></dt><dd>individual external module documentation
    </dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/doc/Symbol-Table.text"><code class="filename">doc/Symbol-Table.text</code></a></span></dt><dd>the mapping between lisp symbols and element IDs
       in these notes (see <a href="impnotes.html#describe" class="olink"><code class="function">DESCRIBE</code></a>),
       installed in <code class="filename">data/</code> under <a href="clisp.html#opt-libdir" class="olink"><code class="varname">CUSTOM:*LIB-DIRECTORY*</code></a>.
    </dd></dl></div></dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/doc/impnotes.html"><code class="filename">doc/impnotes.html</code></a></span></dt><dd>these <a class="ulink" href="http://www.w3.org/MarkUp/" target="_top">HTML</a> implementation notes,
   generated from <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/doc/impnotes.xml.in"><code class="filename">doc/impnotes.xml.in</code></a>
   at <span class="emphasis"><em>release</em></span> time</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="src-i18n"></a>34.3.6. Internationalization</h3></div></div></div><p>These files are usually updated a couple of weeks before a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
 release using <span class="command"><strong>make -f Makefile.devel tp-mail</strong></span>,
 see also <a class="xref" href="#src-external" title="34.3.8. Externally maintained files">Section 34.3.8, “Externally maintained files”</a>.</p><p>We use the
 <a class="ulink" href="http://translationproject.org/domain/clisp.html" target="_top">Translation
  project</a> and the above command sends the updated files to the
  translators.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="filename">src/po/*.pot</code></span></dt><dd>list of translatable messages (<span class="quote">“<span class="quote">portable
    object template</span>”</span>)</dd><dt><span class="term"><code class="filename">src/po/*.po</code></span></dt><dd>translated messages (<span class="quote">“<span class="quote">portable objects</span>”</span>)
</dd><dt><span class="term"><code class="filename">src/po/*.gmo</code></span></dt><dd>translated messages (<span class="quote">“<span class="quote"><a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> format message
    objects</span>”</span>)</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="src-conf-unix"></a>34.3.7. Automatic configuration on <a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> and <a class="ulink" href="http://www.mingw.org/" target="_top"><span class="platform">MinGW</span></a></h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/configure"><code class="filename">configure</code></a></span></dt><dd>the main configuration script
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/version.sh"><code class="filename">version.sh</code></a></span></dt><dd>specifies the current <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> version
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/configure.in"><code class="filename">src/configure.in</code></a></span></dt><dd>lists features to be checked
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/m4/"><code class="filename">src/m4/</code></a></span></dt><dd><p class="simpara">a repertoire of features.
  Use with <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/autoconf/" target="_top">autoconf</a> 2.62</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/m4/clisp.m4"><code class="filename">src/m4/clisp.m4</code></a></span></dt><dd><p>This file defines the macro <code class="function">CL_CLISP</code>
   which takes two optional parameters:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term">features-list</span></dt><dd>The list of <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> features to check.
      E.g., passing <code class="code">[foo bar]</code> results
       in <code class="varname">cl_cv_clisp_FOO</code>
       and <code class="varname">cl_cv_clisp_BAR</code> being defined
       to <span class="returnvalue">yes</span>
       or <span class="returnvalue">no</span>, depending on the value of
       <a href="impnotes.html#features" class="olink"><code class="varname">*FEATURES*</code></a>, i.e., on the return value
       of <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-from-string.html" target="_top"><code class="function">READ-FROM-STRING</code></a> "#+FOO \"yes\" #-FOO \"no\"")</code>.
    </dd><dt><span class="term">required</span></dt><dd><p class="simpara">Determines whether <a class="ulink" href="http://www.gnu.org/software/autoconf/" target="_top"><span class="command"><strong>configure</strong></span></a> should fail
      if <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> or one of the requested features is missing.</p><p class="simpara">Should be <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/true.html"><span class="command"><strong>true</strong></span></a> (the
      default) or <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/false.html"><span class="command"><strong>false</strong></span></a>.</p></dd></dl></div><p class="simpara">Calling this macro causes the generated <a class="ulink" href="http://www.gnu.org/software/autoconf/" target="_top"><span class="command"><strong>configure</strong></span></a> to
    accept the option <code class="option">--with-clisp="clisp command line"</code>
    which allows one to use a specific <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> installation instead of
    <span class="command"><strong><a href="clisp.html#clisp" class="olink">clisp</a></strong></span> in <code class="envar">PATH</code>.</p><p>In addition to the aforementioned per-feature variables,
    this macro defines the follwing variables:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="varname">cl_cv_clisp_version</code></span></dt><dd>The return value of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_lisp-impl_tion-version.html" target="_top"><code class="function">LISP-IMPLEMENTATION-VERSION</code></a>.
     </dd><dt><span class="term"><code class="varname">cl_cv_clisp_libdir</code></span></dt><dd>The <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_namestrin_h-namestring.html" target="_top"><code class="function">NAMESTRING</code></a> of <a href="clisp.html#opt-libdir" class="olink"><code class="varname">CUSTOM:*LIB-DIRECTORY*</code></a>.
     </dd><dt><span class="term"><code class="varname">cl_cv_clisp_linkset</code></span></dt><dd>The directory of the current <a href="impnotes.html#linkset" class="olink">linking set</a>.
     </dd></dl></div><p>
    It also substitues the following variables:</p><table border="0" summary="Simple list" class="simplelist"><tr><td><code class="envar">CLISP_LINKKIT</code></td></tr><tr><td><code class="envar">CLISP_FILES</code></td></tr><tr><td><code class="envar">CLISP_LIBS</code></td></tr><tr><td><code class="envar">CLISP_CFLAGS</code></td></tr><tr><td><code class="envar">CLISP_CPPFLAGS</code></td></tr></table><p>
    (taken from <code class="filename">$cl_cv_clisp_linkset/<a class="link" href="#makevars">makevars</a></code>)
    and <code class="envar">CLISP</code> (the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> command line).</p><p class="simpara">This file is installed in <code class="filename">/usr/share/aclocal</code>
    by <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/make.html"><span class="command"><strong>make install</strong></span></a>.</p></dd></dl></div></dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/configure"><code class="filename">src/configure</code></a></span></dt><dd>configuration script, generated from
   <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/configure.in"><code class="filename">src/configure.in</code></a>
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/intparam.c"><code class="filename">src/intparam.c</code></a></span></dt><dd>figures out some machine parameters (word size,
   endianness etc.)</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/floatparam.c"><code class="filename">src/floatparam.c</code></a></span></dt><dd>figures out some floating point arithmetics parameters
   (rounding, epsilons etc.)</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/config.h.in"><code class="filename">src/config.h.in</code></a></span></dt><dd>header file master, generated from
   <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/configure.in"><code class="filename">src/configure.in</code></a>.
   <code class="filename"><em class="replaceable"><code>build-dir</code></em>/config.h</code>
   contains the values of the features discovered by
   <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/configure"><code class="filename">src/configure</code></a>.
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/makemake.in"><code class="filename">src/makemake.in</code></a></span></dt><dd>makefile construction script master
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/_clisp.c"><code class="filename">src/_clisp.c</code></a></span></dt><dd>master for the distribution's driver program
</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/_distmakefile"><code class="filename">src/_distmakefile</code></a></span></dt><dd>master for the distribution's Makefile
</dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="src-external"></a>34.3.8. Externally maintained files</h3></div></div></div><p>The externally maintained files are usually updated a couple of
 weeks before a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> release using
 <span class="command"><strong>make -f Makefile.devel pre-release</strong></span>,
 see also <a class="xref" href="#src-i18n" title="34.3.6. Internationalization">Section 34.3.6, “Internationalization”</a>.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/gllib/"><code class="filename">src/gllib/</code></a><br /></span><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/glm4/"><code class="filename">src/glm4/</code></a></span></dt><dd><a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> and <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/autoconf/" target="_top">autoconf</a> files from <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/software/gnulib/" target="_top">Portability Library</a>;
   updated using <span class="command"><strong>make -f Makefile.devel gnulib-imported</strong></span>
   at top level.</dd><dt><span class="term"><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/build-aux/"><code class="filename">src/build-aux/</code></a></span></dt><dd>various shell scripts, updated using
   <span class="command"><strong>make -f Makefile.devel build-aux-update</strong></span>
   at top level.</dd></dl></div></div></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="gc"></a>Chapter 35. Overview of <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>'s Garbage Collection</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#internals-intro">35.1. Introduction</a></span></dt><dt><span class="section"><a href="#lisp-obj-in-c">35.2. Lisp objects in <span class="command"><strong>CLISP</strong></span></a></span></dt><dt><span class="section"><a href="#typecodes">35.3. Object Pointer Representations</a></span></dt><dt><span class="section"><a href="#memory-models">35.4. Memory Models</a></span></dt><dt><span class="section"><a href="#gc-safety">35.5. The burden of garbage-collection upon the rest of <span class="command"><strong>CLISP</strong></span></a></span></dt><dd><dl><dt><span class="section"><a href="#gc-moves-data">35.5.1. Lisp <span class="type">object</span> invalidation</a></span></dt><dt><span class="section"><a href="#gc-lisp-in-C">35.5.2. Managing Lisp <span class="type">object</span>s in <span class="command"><strong>C</strong></span></a></span></dt><dt><span class="section"><a href="#gc-alloccount">35.5.3. Run-time GC-safety checks</a></span></dt><dt><span class="section"><a href="#gc-mem-prot">35.5.4. Memory protection</a></span></dt></dl></dd><dt><span class="section"><a href="#foreign-pointers">35.6. Foreign Pointers</a></span></dt><dt><span class="section"><a href="#nextgc-factor">35.7. Forcing or inhibiting Garbage Collections</a></span></dt><dt><span class="section"><a href="#gc-mt">35.8. Garbage Collection and Multithreading</a></span></dt></dl></div><div class="abstract"><p class="title"><strong>Abstract</strong></p><p>These are internals, which are of interest only to the
   <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> developers.  If you do not read <a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-devel/">clisp-devel</a>,
   this chapter is probably not for you.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="internals-intro"></a>35.1. Introduction</h2></div></div></div><p>Knowing that most <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/malloc.html"><code class="function">malloc</code></a> implementations are buggy and/or slow,
and because <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> needs to perform <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion, <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> has its
own memory management subsystem in files <code class="filename">src/spvw*.d</code>,
see <a class="xref" href="#src-modules" title="34.3.1.2. Internal C Modules">Section 34.3.1.2, “Internal <span class="command"><strong>C</strong></span> Modules”</a>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="lisp-obj-in-c"></a>35.2. Lisp objects in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a></h2></div></div></div><div class="orderedlist"><p class="title"><strong>Three kinds of storage are distinguished:</strong></p><ol class="orderedlist" type="1"><li class="listitem"><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> data (the <span class="quote">“<span class="quote">heap</span>”</span>), i.e. storage
  which contains <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="type">object</span></a>s and is managed by the <a href="impnotes.html#gc" class="olink">garbage-collect</a>or.
 </li><li class="listitem"><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> stack (called <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>), contains <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
  <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="type">object</span></a>s visible to the <a href="impnotes.html#gc" class="olink">garbage-collect</a>or</li><li class="listitem"><a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> data (including program text, data,
  <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/malloc.html"><code class="function">malloc</code></a>ed memory)</li></ol></div><p>A <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> object is one word, containing a tag (partial type
information) and either immediate data or a pointer to storage.
Pointers to <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> data have tag = <code class="literal">machine_type</code> = 0,
pointers to <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> stack have tag = <code class="literal">system_type</code>,
most other pointers point to <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> data.</p><div class="variablelist"><a id="immediate-o"></a><p class="title"><strong>Immediate objects</strong></p><dl class="variablelist"><dt><span class="term">32-bit CPU</span></dt><dd><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_fixnum.html" target="_top"><code class="classname">FIXNUM</code></a></td></tr><tr><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SHORT-FLOAT</code></a></td></tr><tr><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a></td></tr></table></dd><dt><span class="term">64-bit CPU</span></dt><dd><p>In addition to the above, </p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SINGLE-FLOAT</code></a> (with <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="strong"><strong><code class="option">TYPECODES</code></strong></span></a>)</td></tr></table></dd></dl></div><p>Let us turn to those <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> objects that consume regular <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> memory.
Every <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> object has a size which is determined when the object is
allocated (using one of the <code class="function">allocate_*()</code> routines).
The size can be computed from the type tag and - if necessary
- the length field of the object's header. The length field always
contains the number of elements of the object. The number of bytes is
given by the function <code class="function">objsize()</code>.</p><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> objects which contain exactly 2 <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> objects
(i.e. <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_cons.html" target="_top"><code class="classname">CONS</code></a>es, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_complex.html" target="_top"><code class="classname">COMPLEX</code></a> numbers, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_ratio.html" target="_top"><code class="classname">RATIO</code></a>s) are
stored in a separate area and occupy 2 words each.
All other <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> objects have <span class="quote">“<span class="quote">varying</span>”</span> length
(more precisely, not a fixed length) and include a word for <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion
purposes at their beginning.</p><p>The garbage collector is invoked every now and then by
 <code class="function">allocate_*()</code> calls according to certain heuristics.
It marks all objects which are <span class="quote">“<span class="quote">alive</span>”</span>
(may be reached from the <span class="quote">“<span class="quote">roots</span>”</span>),
compacts these objects and unmarks them.
Non-live objects are lost; their storage is reclaimed.</p><p>2-pointer objects are compacted by a simple hole-filling
algorithm: fill the left-most object into the right-most hole, and so
on, until the objects are contiguous at the right and the hole is
contiguous at the left.</p><p>Variable-length objects are compacted by sliding them down (their
address decreases).</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="typecodes"></a>35.3. Object Pointer Representations</h2></div></div></div><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> implements two ways of representing object pointers.
(An object pointer, <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> type <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="type">object</span></a>, contains a
pointer to the memory location of the object, or - for <a class="link" href="#immediate-o" title="Immediate objects">immediate object</a>
 - all bits of the object itself.)
Both of them have some things in common:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">There is a distinction between <a class="link" href="#immediate-o" title="Immediate objects">immediate object</a>s
   (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_character.html" target="_top"><code class="classname">CHARACTER</code></a>s, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_fixnum.html" target="_top"><code class="classname">FIXNUM</code></a>s, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_short-flo_m_long-float.html" target="_top"><code class="classname">SHORT-FLOAT</code></a>s, etc) and
   heap allocated objects.</li><li class="listitem">All object pointers are typed, i.e. contain a few
   bits of information about the type of the pointed-to object. At a
   minimum, these bits must allow to distinguish immediate and
   heap-allocated objects.</li><li class="listitem">Not all of the type information is contained in the
   object pointer.  For example, <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> objects can change their type
   when <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_change-class.html" target="_top"><code class="function">CHANGE-CLASS</code></a> is called. To avoid scanning all the heap for
   references when this happens, the class information is stored in the
   heap allocated object, not in the object pointer.</li></ul></div><p>The <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="strong"><strong><code class="option">HEAPCODES</code></strong></span></a> object representation has a minimum of type
bits in the object pointer, namely, 2 bits. They allow to distinguish
<a class="link" href="#immediate-o" title="Immediate objects">immediate object</a>s (which have some more type bits), <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_cons.html" target="_top"><code class="classname">CONS</code></a>es (which
have no type bits in the heap, since they occupy just two words in the
heap, with no header), other heap objects (many, from <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-vector.html" target="_top"><code class="classname">SIMPLE-VECTOR</code></a>s
to <a class="link" href="#fptr"><code class="classname">FFI:FOREIGN-POINTER</code></a>s), and <span class="type">Subr</span>s. Most object types are
distinguished by looking a the <em class="structfield"><code>rectype</code></em> field
in the header of the heap object.</p><p>The <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="strong"><strong><code class="option">TYPECODES</code></strong></span></a> object representation has about two dozen of types
encoded in 6 or 7 bits in the object pointer.
Typically these are the upper 8 bits of a word (on a 32-bit machine) or
the upper 16 bits or 32 bits of a word (on a 64-bit machine).
The particular values of the typecodes allow many common operations to
be performed with a single bit test (e.g. <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_consp.html" target="_top"><code class="function">CONSP</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_minuspcm_plusp.html" target="_top"><code class="function">MINUSP</code></a> for a
<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_real.html" target="_top"><code class="classname">REAL</code></a> are bit tests) or range check.
However, the <em class="structfield"><code>rectype</code></em> field still exists for
many types, because there are many built-in types which do not need a
particularly fast type test.</p><p>Which object representation is chosen is decided at build time
depending on the available preprocessor definitions. You can define
<a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="strong"><strong><code class="option">TYPECODES</code></strong></span></a> or <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="strong"><strong><code class="option">HEAPCODES</code></strong></span></a> to force one or the other.</p><p>One might expect that <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="strong"><strong><code class="option">TYPECODES</code></strong></span></a> is faster than <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="strong"><strong><code class="option">HEAPCODES</code></strong></span></a>
because it does not need to make as many memory accesses. This effect
is, however, hardly measurable in practice (certainly not more than 5%
faster).  Apparently because, first, the situations where the type of an
object is requested but then the object is not looked into are rare.
It is much more common to look into an object, regardless of its type.
Second, due to the existence of data caches in the CPU, accessing a heap
location twice, once for the type test and then immediately afterwards
for the data, is not significantly slower than just accessing the
data.</p><p><a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="strong"><strong><code class="option">TYPECODES</code></strong></span></a> is problematic on 32-bit machines, when you want to
use more than 16 MB of memory, because the type bits (at bit 31..24)
interfere with the bits of a heap address. For this reason,
<a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="strong"><strong><code class="option">HEAPCODES</code></strong></span></a> is the default on 32-bit platforms.</p><p><a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="strong"><strong><code class="option">HEAPCODES</code></strong></span></a> is problematic on platforms whose object alignment
is less than 4. This affects only the mc680x0 CPU; however, here the
alignment can usually be guaranteed through some <a class="ulink" href="http://gcc.gnu.org/" target="_top"><span class="command"><strong>gcc</strong></span></a> options.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="memory-models"></a>35.4. Memory Models</h2></div></div></div><p>There are 6 memory models. Which one is used, depends on the
operating system and is determined at build time.</p><div class="variablelist"><p class="title"><strong>Memory Models</strong></p><dl class="variablelist"><dt><span class="term">SPVW_MIXED_BLOCKS_OPPOSITE</span></dt><dd><p>The heap consists of one block of fixed length
  (allocated at startup).
  The variable-length objects are allocated from the left, the 2-pointer
  objects are allocated from the right.
  There is a hole between them.
  When the hole shrinks to 0, <a href="impnotes.html#gc" class="olink">garbage-collect</a> is invoked.
  <a href="impnotes.html#gc" class="olink">garbage-collect</a> slides the variable-length objects to the left and concentrates
  the 2-pointer objects at the right end of the block again.
  When no more room is available, some reserve area beyond the right end
  of the block is halved, and the 2-pointer objects are moved to the
  right accordingly.
  </p><div class="variablelist"><p class="title"><strong>Advantages and Disadvantages</strong></p><table border="0" class="variablelist"><colgroup><col align="left" valign="top" /><col /></colgroup><tbody><tr><td><p><span class="term">(+)</span></p></td><td>Simple management.
    </td></tr><tr><td><p><span class="term">(+)</span></p></td><td>No fragmentation at all.
    </td></tr><tr><td><p><span class="term">(-)</span></p></td><td>The total heap size is limited.
    </td></tr></tbody></table></div><p>
 </p></dd><dt><span class="term">SPVW_MIXED_BLOCKS_OPPOSITE &amp; TRIVIALMAP_MEMORY</span></dt><dd><p>The heap consists of two big blocks, one for
  variable-length objects and one for 2-pointer objects.
  The former one has a hole to the right and is extensible to the right,
  the latter one has a hole to the left and is extensible to the left.
  Similar to the previous model, except that the hole is unmapped.
  </p><div class="variablelist"><p class="title"><strong>Advantages and Disadvantages</strong></p><table border="0" class="variablelist"><colgroup><col align="left" valign="top" /><col /></colgroup><tbody><tr><td><p><span class="term">(+)</span></p></td><td>Total heap size grows depending on the
     application's needs.</td></tr><tr><td><p><span class="term">(+)</span></p></td><td>No fragmentation at all.
    </td></tr><tr><td><p><span class="term">(*)</span></p></td><td>Works only when SINGLEMAP_MEMORY is
     possible as well.</td></tr></tbody></table></div><p>
 </p></dd><dt><span class="term">SPVW_MIXED_BLOCKS_STAGGERED &amp; TRIVIALMAP_MEMORY</span></dt><dd><p>The heap consists of two big blocks, one for
  variable-length objects and one for 2-pointer objects.
  Both have a hole to the right, but are extensible to the right.
  </p><div class="variablelist"><p class="title"><strong>Advantages and Disadvantages</strong></p><table border="0" class="variablelist"><colgroup><col align="left" valign="top" /><col /></colgroup><tbody><tr><td><p><span class="term">(+)</span></p></td><td>Total heap size grows depending on the
     application's needs.</td></tr><tr><td><p><span class="term">(+)</span></p></td><td>No fragmentation at all.
    </td></tr><tr><td><p><span class="term">(*)</span></p></td><td>Works only when SINGLEMAP_MEMORY is
     possible as well.</td></tr></tbody></table></div><p>
 </p></dd><dt><span class="term">SPVW_MIXED_PAGES</span></dt><dd><p>The heap consists of many small pages (usually around 8 KB).
  There are two kinds of pages: one for 2-pointer objects, one for
  variable-length objects.
  The set of all pages of a fixed kind is called a "Heap".
  Each page has its hole (free space) at its end.
  For every heap, the pages are kept sorted according to the size of
  their hole, using AVL trees.
  The <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion is invoked when the used space has grown by 25% since the
  last GC; until that point new pages are allocated from the OS.
  The GC compacts the data in each page separately:
  data is moved to the left. Emptied pages are given back to the OS.
  If the holes then make up more than 25% of the occupied storage, a
  second GC turn moves objects across pages, from nearly empty ones to
  nearly full ones, with the aim to free as many pages as possible.
  </p><div class="variablelist"><p class="title"><strong>Advantages and Disadvantages</strong></p><table border="0" class="variablelist"><colgroup><col align="left" valign="top" /><col /></colgroup><tbody><tr><td><p><span class="term">(-)</span></p></td><td>Every allocation requires AVL tree operations,
     thus slower</td></tr><tr><td><p><span class="term">(+)</span></p></td><td>Total heap size grows depending on the
     application's needs.</td></tr><tr><td><p><span class="term">(+)</span></p></td><td>Works on operating systems which do not provide
     large contiguous areas.</td></tr></tbody></table></div><p>
 </p></dd><dt><span class="term">SPVW_PURE_PAGES</span></dt><dd><p>Just like SPVW_MIXED_PAGES, except that every page
  contains data of only a single type tag, i.e. there is a Heap for
  every type tag.
  </p><div class="variablelist"><p class="title"><strong>Advantages and Disadvantages</strong></p><table border="0" class="variablelist"><colgroup><col align="left" valign="top" /><col /></colgroup><tbody><tr><td><p><span class="term">(-)</span></p></td><td>Every allocation requires AVL tree operations,
     thus slower</td></tr><tr><td><p><span class="term">(+)</span></p></td><td>Total heap size grows depending on the
     application's needs.</td></tr><tr><td><p><span class="term">(+)</span></p></td><td>Works on operating systems which do not provide
     large contiguous areas.</td></tr><tr><td><p><span class="term">(-)</span></p></td><td>More fragmentation because objects of different
    type never fit into the same page.</td></tr></tbody></table></div></dd><dt><span class="term">SPVW_PURE_BLOCKS</span></dt><dd><p>There is a big block of storage for each type tag.
  Each of these blocks has its data to the left and the hole to the
  right, but these blocks are extensible to the right (because there is
  enough room between them).
  A <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion is triggered when the allocation amount since the
  last GC reaches 50% of the amount of used space at the last GC, but at
  least 512 KB.
  The <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion cleans up each block separately: data is moved left.
  </p><div class="variablelist"><p class="title"><strong>Advantages and Disadvantages</strong></p><table border="0" class="variablelist"><colgroup><col align="left" valign="top" /><col /></colgroup><tbody><tr><td><p><span class="term">(+)</span></p></td><td>Total heap size grows depending on the
     application's needs.</td></tr><tr><td><p><span class="term">(+)</span></p></td><td>No 16 MB total size limit.
    </td></tr><tr><td><p><span class="term">(*)</span></p></td><td>Works only in combination with SINGLEMAP_MEMORY.
    </td></tr></tbody></table></div><p>
 </p></dd></dl></div><p>In page based memory models, an object larger than a page is the
only object carried by its pages.
There are no small objects in pages belonging to a big object.</p><p>The following combinations of memory model and
 <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/mmap.html"><code class="function">mmap</code></a> tricks are possible (the number
 indicates the order in which the respective models have been
 developed):</p><div class="table"><a id="mem-models-comb-typecodes"></a><p class="title"><strong>Table 35.1. Memory models with <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="strong"><strong><code class="option">TYPECODES</code></strong></span></a></strong></p><div class="table-contents"><table class="table" summary="Memory models with TYPECODES" border="1"><colgroup><col /><col /><col /><col /><col /></colgroup><thead><tr><th align="center"> </th><th align="center"><a class="xref" href="#MMC-A">A</a></th><th align="center"><a class="xref" href="#MMC-B">B</a></th><th align="center"><a class="xref" href="#MMC-C">C</a></th><th align="center"><a class="xref" href="#MMC-D">D</a></th></tr></thead><tbody><tr><td align="center">SPVW_MIXED_BLOCKS_OPPOSITE</td><td align="center">1</td><td align="center">9</td><td align="center"> </td><td align="center">8</td></tr><tr><td align="center">SPVW_MIXED_BLOCKS_STAGGERED</td><td align="center"> </td><td align="center">6</td><td align="center"> </td><td align="center">7</td></tr><tr><td align="center">SPVW_PURE_BLOCKS</td><td align="center"> </td><td align="center"> </td><td align="center">4</td><td align="center">5</td></tr><tr><td align="center">SPVW_MIXED_PAGES</td><td align="center">2</td><td align="center"> </td><td align="center"> </td><td align="center"> </td></tr><tr><td align="center">SPVW_PURE_PAGES</td><td align="center">3</td><td align="center"> </td><td align="center"> </td><td align="center"> </td></tr></tbody></table></div></div><br class="table-break" /><div class="table"><a id="mem-models-comb-heapcodes"></a><p class="title"><strong>Table 35.2. Memory models with <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="strong"><strong><code class="option">HEAPCODES</code></strong></span></a></strong></p><div class="table-contents"><table class="table" summary="Memory models with HEAPCODES" border="1"><colgroup><col /><col /><col /><col /></colgroup><thead><tr><th align="center"> </th><th align="center"><a class="xref" href="#MMC-A">A</a></th><th align="center"><a class="xref" href="#MMC-B">B</a></th><th align="center"><a class="xref" href="#MMC-D">D</a></th></tr></thead><tbody><tr><td align="center">SPVW_MIXED_BLOCKS_OPPOSITE</td><td align="center">*</td><td align="center">*</td><td align="center">*</td></tr><tr><td align="center">SPVW_MIXED_BLOCKS_STAGGERED</td><td align="center"> </td><td align="center">*</td><td align="center">*</td></tr><tr><td align="center">SPVW_MIXED_PAGES</td><td align="center">*</td><td align="center"> </td><td align="center"> </td></tr></tbody></table></div></div><br class="table-break" /><div class="orderedlist"><p class="title"><strong>Legend to
  <a class="xref" href="#mem-models-comb-typecodes" title="Table 35.1. Memory models with TYPECODES">Table 35.1, “Memory models with <span class="strong"><strong><code class="option">TYPECODES</code></strong></span>”</a> and
  <a class="xref" href="#mem-models-comb-heapcodes" title="Table 35.2. Memory models with HEAPCODES">Table 35.2, “Memory models with <span class="strong"><strong><code class="option">HEAPCODES</code></strong></span>”</a></strong></p><ol class="orderedlist" type="A"><li class="listitem"><a id="MMC-A"></a>no MAP_MEMORY</li><li class="listitem"><a id="MMC-B"></a>TRIVIALMAP_MEMORY</li><li class="listitem"><a id="MMC-C"></a>SINGLEMAP_MEMORY</li><li class="listitem"><a id="MMC-D"></a>GENERATIONAL_GC</li></ol></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="gc-safety"></a>35.5. The burden of <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion upon the rest of <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#gc-moves-data">35.5.1. Lisp <span class="type">object</span> invalidation</a></span></dt><dt><span class="section"><a href="#gc-lisp-in-C">35.5.2. Managing Lisp <span class="type">object</span>s in <span class="command"><strong>C</strong></span></a></span></dt><dt><span class="section"><a href="#gc-alloccount">35.5.3. Run-time GC-safety checks</a></span></dt><dt><span class="section"><a href="#gc-mem-prot">35.5.4. Memory protection</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="gc-moves-data"></a>35.5.1. Lisp <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="type">object</span></a> invalidation</h3></div></div></div><p>Every subroutine marked with <span class="quote">“<span class="quote">can trigger GC</span>”</span>
or <code class="literal">maygc</code> may invoke <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion.
The <a href="impnotes.html#gc" class="olink">garbage-collect</a>or moves all the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> non-<a class="link" href="#immediate-o" title="Immediate objects">immediate object</a>s and updates the pointers.
But the <a href="impnotes.html#gc" class="olink">garbage-collect</a>or looks only at the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> and not in the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>
variables. (Anything else would not be portable.)
Therefore at every "unsafe" point, i.e. every call to such a subroutine,
all the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> variables of type <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="type">object</span></a>
<span class="strong"><strong>MUST BE ASSUMED TO BECOME GARBAGE</strong></span>.
(Except for <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="type">object</span></a>s that are known to be unmovable,
 e.g. <a class="link" href="#immediate-o" title="Immediate objects">immediate object</a>s or <span class="type">Subr</span>s.)
Pointers inside <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> data (e.g. to the characters of a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>
or to the elements of a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-vector.html" target="_top"><code class="classname">SIMPLE-VECTOR</code></a>) become
<span class="strong"><strong>INVALID</strong></span> as well.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="gc-lisp-in-C"></a>35.5.2. Managing Lisp <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="type">object</span></a>s in <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a></h3></div></div></div><p>The workaround is usually to allocate all the needed <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> data
first and do the rest of the computation with <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> variables,
without calling unsafe routines, and without worrying about <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion.</p><p>Alternatively, you can save a lisp <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="type">object</span></a> on the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> using
 macros <code class="function">pushSTACK()</code> and <code class="function">popSTACK()</code>.
</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>One should <span class="strong"><strong>not</strong></span> mix these macros with functions
  which modify <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> in one statement because <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> may execute
  different parts of the statement out of order.
  E.g.,</p><pre class="programlisting">pushSTACK(listof(4));</pre><p>
  is <span class="emphasis"><em>illegal</em></span> while
  </p><pre class="programlisting">pushSTACK(STACK_0);</pre><p>
  is <span class="emphasis"><em>legal</em></span>.</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="gc-alloccount"></a>35.5.3. Run-time GC-safety checks</h3></div></div></div><p>Run-time GC-safety checking is available when you build <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
 with a C++ compiler, e.g.:
<a id="clisp-config-gxx"></a></p><pre class="screen">
<strong><code class="prompt">$</code></strong> ./configure 'CC=g++' <a href="impnotes.html#with-debug" class="olink"><code class="option">--with-debug</code></a> build-g-gxx
</pre><p>
When built like this, <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> will <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/abort.html"><code class="function">abort</code></a>
when you reference GC-unsafe data after an allocation (which could have
triggered a <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion), and <a class="ulink" href="http://sources.redhat.com/gdb/" target="_top"><span class="command"><strong>gdb</strong></span></a> will pinpoint the trouble spot.</p><p>Specifically, when <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> is configured
 as <a class="link" href="#clisp-config-gxx">above</a>, there is a
global integer variable <code class="varname">alloccount</code> and the <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="type">object</span></a>
structure contains an integer <em class="structfield"><code>allocstamp</code></em>
slot. If these two integers are not the same, the <a class="link" href="#typecodes" title="35.3. Object Pointer Representations"><span class="type">object</span></a> is invalid.
By playing with <a class="ulink" href="http://sources.redhat.com/gdb/" target="_top"><span class="command"><strong>gdb</strong></span></a>, you should be able to figure out the precise spot
where an allocation increments <code class="varname">alloccount</code>
<span class="strong"><strong>after</strong></span> the object has been retrieved from a GC-visible location.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="gc-mem-prot"></a>35.5.4. Memory protection</h3></div></div></div><p>Generational <a href="impnotes.html#gc" class="olink">garbage-collect</a>or uses memory protection, so when passing pointers
 into the lisp heap to <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> functions, you may encounter errors
 (<a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/errno.html"><code class="varname">errno</code></a>=<code class="constant">EFAULT</code>) unless you call
 <code class="function">handle_fault_range(protection,region_start,region_end)</code>
 on the appropriate memory region.  See files </p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/unixaux.d"><code class="filename">src/unixaux.d</code></a></td></tr><tr><td><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/win32aux.d"><code class="filename">src/win32aux.d</code></a></td></tr><tr><td><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/syscalls/calls.c"><code class="filename">modules/syscalls/calls.c</code></a></td></tr><tr><td><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/rawsock/rawsock.c"><code class="filename">modules/rawsock/rawsock.c</code></a></td></tr></table><p> for examples.</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="foreign-pointers"></a>35.6. Foreign Pointers</h2></div></div></div><p>Pointers to <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> functions and to <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/malloc.html"><code class="function">malloc</code></a>ed data can be
hidden in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> objects of type <span class="type">machine_type</span>;
<a href="impnotes.html#gc" class="olink">garbage-collect</a> will not modify its value.
But one should not dare to assume that a <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> stack pointer
or the address of a <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> function in a shared library satisfies the
same requirements.</p><p>If another pointer is to be viewed as a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> object, it is best
to box it, e.g. in a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-bit-vector.html" target="_top"><code class="classname">SIMPLE-BIT-VECTOR</code></a> or in an
<span class="type">Fpointer</span> (using <code class="function">allocate_fpointer()</code>.)</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="nextgc-factor"></a>35.7. Forcing or inhibiting Garbage Collections</h2></div></div></div><p>Here are some tips to debug <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion-related problems.</p><p>It is possible to force <a href="impnotes.html#gc" class="olink">garbage-collect</a>ions to occur at specific points, by inserting
calls to <code class="function">EXT:GC</code> in the code.</p><p>It is also possible to make <a href="impnotes.html#gc" class="olink">garbage-collect</a>ions more frequent overall, by use of the
command-line option <code class="option">-nextgc-factor</code>. This option specifies a
factor that gets applied to the amount of space that can be consumed before
the next <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion is triggered. If you specify a factor smaller than 1, the
frequency of <a href="impnotes.html#gc" class="olink">garbage-collect</a>ions is increased. For example,
<code class="literal"><code class="option">-nextgc-factor</code> 0.001</code> reduces the
"Bytes available until next GC" value displayed by the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_room.html" target="_top"><code class="function">ROOM</code></a> function by a
factor of 1000, and thus makes <a href="impnotes.html#gc" class="olink">garbage-collect</a>ions 1000 times more frequent.</p><p>It is equally possible to make <a href="impnotes.html#gc" class="olink">garbage-collect</a>ions less frequent. To this effect,
you pass to <code class="option">-nextgc-factor</code> a value larger than 1. For example,
<code class="literal"><code class="option">-nextgc-factor</code> 1e9</code> multiplies the
"Bytes available until next GC" value displayed by the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_room.html" target="_top"><code class="function">ROOM</code></a> function with a
factor of 1000000000, and thus effectively inhibits <a href="impnotes.html#gc" class="olink">garbage-collect</a>ions entirely.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="gc-mt"></a>35.8. Garbage Collection and Multithreading</h2></div></div></div><p>While the <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion is executing, all other threads must stop.
 <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> has a copying <a href="impnotes.html#gc" class="olink">garbage-collect</a>or, so anything else would require a write
 barrier during the scan phase and a read barrier during the move phase.</p><p><a id="gc-mt-pin"></a><strong>Pinned heap objects. </strong>Heap objects may be <span class="emphasis"><em>pinned</em></span> - they will not
  move during <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion.  Used when execution is blocked in a
  foreign/system call and a pointer into the heap is passed to non-lisp
  land.  The <a href="impnotes.html#gc" class="olink">garbage-collect</a>or tries to minimize the holes in the heap introduced
  by the <span class="emphasis"><em>pinning</em></span> process.
  See also the note about system calls in
  <a class="xref" href="#clisp-h" title="32.2.7.2. clisp.h">Section 32.2.7.2, “clisp.h”</a>.</p><p><a id="gc-mt-safe-points"></a><strong>Safe points. </strong>The threads may be stopped only at certain safe points.
  Currently implemented safe points are:</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">Any heap allocation (actually before the
     allocation itself).</li><li class="listitem">Possibly blocking system call.</li><li class="listitem">Some places that may introduce infinite non-consing
       loops.</li></ol></div><p>
   Basically any thread that conses or can block in a system call will
   not stop the <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion from executing. There are still places where infinite
   non-consing loop without safe point may be reached (TODO: find and fix)</p></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="extend"></a>Chapter 36. Extending <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> Core</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#add-fun">36.1. Adding a built-in function</a></span></dt><dt><span class="section"><a href="#add-var">36.2. Adding a built-in variable</a></span></dt><dt><span class="section"><a href="#recompile">36.3. Recompilation</a></span></dt></dl></div><p>You are urged to use <a class="link" href="#modules" title="32.2. External Modules">External
  Modules</a> instead of adding built-in functions.</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> comes with an <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> which allows you
 to access <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> libraries in an easy way (including creating
 <a class="link" href="#dffi-make-func"><code class="function">FFI:FOREIGN-FUNCTION</code></a>s dynamically).</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="add-fun"></a>36.1. Adding a built-in function</h2></div></div></div><p>In the rare cases when you really need to modify <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
 internals and add a truly built-in function, you should read the
 <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> sources for inspiration and enlightenment, choose a file where
 your brand-new built-in function should go to, and then ...
 </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">add the <code class="function">LISPFUN</code>
    form and the implementation there</li><li class="listitem">add the <code class="function">LISPFUN</code> header to
    file <a class="link" href="#subr-d"><code class="filename">subr.d</code></a></li><li class="listitem">declare the function name in file <a class="link" href="#constsym-d"><code class="filename">constsym.d</code></a> in
    the appropriate package (probably <a class="link" href="#ext-pac"><strong class="package"><span class="quote">“<span class="quote">EXT</span>”</span></strong></a>, if there is no specific
    package)</li><li class="listitem">if your function accepts keyword arguments, then you must
    make sure that the keyword symbols are declared in <a class="link" href="#constsym-d"><code class="filename">constsym.d</code></a>
  </li><li class="listitem">see the example in <a class="xref" href="#modprep" title="32.2.7.1. Modprep">Section 32.2.7.1, “Modprep”</a> for
    argument passing and returning values</li><li class="listitem">export your function name from the appropriate
    package in file <a class="link" href="#init-lisp"><code class="filename">init.lisp</code></a></li><li class="listitem">when you are done, you should run
    <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/make.html"><span class="command"><strong>make check-sources</strong></span></a> in your build directory:
    this will check that the definitions (source files) and the declarations
    (<a class="link" href="#subr-d"><code class="filename">subr.d</code></a> and <a class="link" href="#fsubr-d"><code class="filename">fsubr.d</code></a>) are in sync.</li></ul></div><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>Be very careful with the <span class="emphasis"><em>GC-unsafe</em></span>
  functions!  Always remember about <a class="link" href="#gc-safety" title="35.5. The burden of garbage-collection upon the rest of CLISP">GC-safety</a>!</p></div><p>These instructions are intentionally terse - you are encouraged to
 use <a href="impnotes.html#modules" class="olink">module</a>s and/or <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a> instead of adding built-ins directly.
</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="add-var"></a>36.2. Adding a built-in variable</h2></div></div></div><p>If you must be able to access the Lisp variable in the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>
 code, follow these steps:
 </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">declare the variable name
    in <a class="link" href="#constsym-d"><code class="filename">constsym.d</code></a> in the appropriate package
    (probably <a class="link" href="#customize" title="31.12. Customizing CLISP behavior"><strong class="package"><span class="quote">“<span class="quote">CUSTOM</span>”</span></strong></a>, if there is no specific package);
  </li><li class="listitem">add a <code class="function">define_variable()</code> call
    in function <code class="function">init_symbol_values()</code>
    in file <a class="link" href="#spvw-d"><code class="filename">spvw.d</code></a></li><li class="listitem">export your variable name from the appropriate
    package in file <a class="link" href="#init-lisp"><code class="filename">init.lisp</code></a></li></ul></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="recompile"></a>36.3. Recompilation</h2></div></div></div><p><span class="emphasis"><em>Any</em></span> change that forces <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/make.html"><span class="command"><strong>make</strong></span></a> to remake <code class="filename">lisp.run</code>,
 will force recompilation of all <code class="filename">#P".lisp"</code> files and
 re-dumping of <a class="link" href="#image" title="31.2. Saving an Image"><code class="filename">lispinit.mem</code></a>, which may be time-consuming.  This is not
 always necessary, depending on what kind of change you introduced.
</p><p>On the other hand, if you change any of the following files:
 </p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="link" href="#constobj-d"><code class="filename">constobj.d</code></a></td></tr><tr><td><a class="link" href="#constsym-d"><code class="filename">constsym.d</code></a></td></tr><tr><td><a class="link" href="#fsubr-d"><code class="filename">fsubr.d</code></a></td></tr><tr><td><a class="link" href="#subr-d"><code class="filename">subr.d</code></a></td></tr></table><p>
 your <a class="link" href="#image" title="31.2. Saving an Image"><code class="filename">lispinit.mem</code></a> will <span class="emphasis"><em>have</em></span> to be re-dumped.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title"><a id="byte-version"></a>Warning</h3><p>If you change the signature of any
 system function mentioned in the <a class="link" href="#byte-version" title="Warning"><code class="varname">FUNTAB</code></a>* arrays in
 file <a class="link" href="#eval-d"><code class="filename">eval.d</code></a>, all the <code class="filename">#P".fas"</code> files will
 become obsolete and will need to be recompiled.
 You will need to add a note to that effect to the <a class="link" href="#src-news"><code class="filename">src/NEWS</code></a> file
 and augment the object <code class="literal">version</code> in file <a class="link" href="#constobj-d"><code class="filename">constobj.d</code></a>.
 <span class="emphasis"><em>Please try to avoid this as much as possible</em></span>.
</p></div></div></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="bytecode"></a>Chapter 37. The <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> bytecode specification</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#byte-intro">37.1. Introduction</a></span></dt><dt><span class="section"><a href="#vm">37.2. The virtual machine</a></span></dt><dt><span class="section"><a href="#comp-fun">37.3. The structure of compiled functions</a></span></dt><dt><span class="section"><a href="#instr-struct">37.4. The general structure of the instructions</a></span></dt><dt><span class="section"><a href="#instr-set">37.5. The instruction set</a></span></dt><dd><dl><dt><span class="section"><a href="#instr-const">37.5.1. Instructions for constants</a></span></dt><dt><span class="section"><a href="#instr-lex-var">37.5.2. Instructions for lexical variables</a></span></dt><dt><span class="section"><a href="#instr-dyn-var">37.5.3. Instructions for dynamic variables</a></span></dt><dt><span class="section"><a href="#instr-stack">37.5.4. Instructions for stack operations</a></span></dt><dt><span class="section"><a href="#instr-jump">37.5.5. Instructions for control flow, jumps</a></span></dt><dt><span class="section"><a href="#instr-env">37.5.6. Instructions for lexical environment,    creation of closures</a></span></dt><dt><span class="section"><a href="#instr-funcall">37.5.7. Instructions for function calls</a></span></dt><dt><span class="section"><a href="#instr-optkey">37.5.8. Instructions for optional   and keyword parameters</a></span></dt><dt><span class="section"><a href="#instr-mulval">37.5.9. Instructions for multiple values</a></span></dt><dt><span class="section"><a href="#instr-block">37.5.10. Instructions for    <code class="function">BLOCK</code> and <code class="function">RETURN-FROM</code></a></span></dt><dt><span class="section"><a href="#instr-tagbody">37.5.11. Instructions for <code class="function">TAGBODY</code> and <code class="function">GO</code></a></span></dt><dt><span class="section"><a href="#instr-catch">37.5.12. Instructions for <code class="function">CATCH</code> and <code class="function">THROW</code></a></span></dt><dt><span class="section"><a href="#instr-unwind">37.5.13. Instructions for <code class="function">UNWIND-PROTECT</code></a></span></dt><dt><span class="section"><a href="#instr-handler">37.5.14. Instructions for <code class="function">HANDLER-BIND</code></a></span></dt><dt><span class="section"><a href="#instr-inline">37.5.15. Instructions for some inlined   functions</a></span></dt><dt><span class="section"><a href="#instr-combo">37.5.16. Combined instructions</a></span></dt><dt><span class="section"><a href="#instr-shortcut">37.5.17. Shortcut instructions</a></span></dt></dl></dd><dt><span class="section"><a href="#compiler-introspection">37.6. Examining compiled closures</a></span></dt><dt><span class="section"><a href="#bytecode-design">37.7. Bytecode Design</a></span></dt><dd><dl><dt><span class="section"><a href="#byte-when-add-q">37.7.1. When to add a new bytecode?</a></span></dt><dt><span class="section"><a href="#byte-jmptail-q">37.7.2. Why JMPTAIL?</a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="byte-intro"></a>37.1. Introduction</h2></div></div></div><p>The <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> compiler compiles <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> programs into instruction codes
for a virtual processor.  This bytecode is optimized for saving space in
the most common cases of <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> programs.  The main advantages/drawbacks
of this approach, compared to native code compilation, are:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Bytecode compiled programs are a lot smaller than
  when compiled to native code.  This results in better use of CPU
  caches, and in less virtual memory paging. Users perceive this as good
  responsiveness.</li><li class="listitem">Maximum execution speed (throughput in tight loops)
   is limited.</li><li class="listitem">Since no bytecode instructions are provided for
   <span class="quote">“<span class="quote">unsafe</span>”</span> operations (like unchecked array accesses,
   or <span class="quote">“<span class="quote">fast</span>”</span> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CAR</code></a>/<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDR</code></a>), programs run with all safety
   checks enabled even when compiled.</li><li class="listitem">Execution speed of a program can easily be
   understood by looking at the output of the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_disassemble.html" target="_top"><code class="function">DISASSEMBLE</code></a> function.
   A rule of thumb is that every elementary instruction costs 1 time
   unit, whereas a function call costs 3 to 4 time units.
  </li><li class="listitem">Needing to do no type inference, the compiler is
   pretty straightforward and fast.  As a consequence, the definition of
   <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-7.html"><span class="command"><strong>CLOS</strong></span></a> generic functions, which needs to compile small pieces of
   generated code, is not perceived to be slow.</li><li class="listitem">The compiler is independent from the hardware CPU.
   Different back-ends, one for each hardware CPU, are not needed.  As a
   consequence, the compiler is fairly small (and would have been easily
   maintainable if it were written in a less kludgey way...), and it is
   impossible for the compiler writer to introduce CPU dependent bugs.
 </li></ul></div><p>
</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="vm"></a>37.2. The virtual machine</h2></div></div></div><p>The bytecode can be thought of as being interpreted by a virtual
processor.  The engine which interprets the bytecode (the
<span class="quote">“<span class="quote">implementation of the virtual machine</span>”</span>) is either a
<a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> function (<code class="function">interpret_bytecode</code> in <a class="link" href="#eval-d"><code class="filename">eval.d</code></a>),
or a just-in-time compiler which translates a function's bytecode into
hardware CPU instructions the first time said function is called,
see <a class="xref" href="#compile-jit" title="3.2.1.1. Just-In-Time Native Compilation">Section 3.2.1.1, “Just-In-Time Native Compilation”</a>.</p><p>The virtual machine is a stack machine with two stacks:
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a></span></dt><dd>a stack for <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> objects and frames
   (<span class="quote">“<span class="quote">Lisp stack</span>”</span>).</dd><dt><span class="term"><a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a></span></dt><dd>a stack for other data and pointers
   (<span class="quote">“<span class="quote">Program stack</span>”</span>).</dd></dl></div><p>This two-stack architecture permits to save an unlimited number of
<a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> objects on the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> (needed for handling of <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_m.html#multiple_values">multiple values</a>),
without <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#cons">cons</a>ing[3].  Also, in a world with a compacting no-ambiguous-roots
garbage collector, <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> must only hold <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> objects, and <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> can
hold all the other data belonging to a frame, which would not fit into
<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> without tagging/untagging overhead.</p><p>The scope of <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> and <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> is only valid for a given function
invocation.  Whereas the amount of <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> space needed for executing a
function (excluding other function calls) is unlimited, the amount of
<a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> space needed is known a priori, at compile time.  When a function
is called, no relation is specified between the caller's <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> and the
callee's <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>, and between the caller's <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> and the callee's <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a>.
The bytecode is designed so that outgoing arguments on the caller's
<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> can be shared by the caller's incoming arguments area (on the
callee's <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>), but a virtual machine implementation may also copy
outgoing arguments to incoming arguments instead of sharing them.</p><p>The virtual machine has a special data structure,
<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>, containing the <span class="quote">“<span class="quote">top of stack</span>”</span>,
specially adapted to <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_m.html#multiple_values">multiple values</a>:
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a></span></dt><dd>an unsigned integer.
  </dd><dt><span class="term"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a></span></dt><dd>the <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#primary_value">primary value</a>, a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> object.
  If <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> = 0, this is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</dd><dt><span class="term"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_space</code></a></span></dt><dd>all values except the first one, an array of <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
  objects.</dd></dl></div><p>The contents of <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a> is short-lived.
It does not survive a function call, not even a <a href="impnotes.html#gc" class="olink">garbage-collect</a>ion.</p><p>The interpretation of some bytecode instructions depends on a
constant, <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a>.  This is a CPU-dependent number, the value of
<code class="varname">SYSTEM::*JMPBUF-SIZE*</code>.  In <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>, it is defined as
<code class="literal">ceiling(sizeof(jmp_buf),sizeof(void*))</code>.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="comp-fun"></a>37.3. The structure of compiled functions</h2></div></div></div><p>A compiled function consists of two objects: The function itself,
containing the references to all <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> objects needed for the bytecode,
and a byte vector containing only immediate data, including the bytecode
proper.</p><p>Typically, the byte vector is about twice as large as the function
vector.  The separation thus helps the garbage collector (since the byte
vector does not need to be scanned for pointers).</p><p>A function looks like this
 (cf. the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> type <span class="type">Cclosure</span>):
</p><div class="variablelist"><dl class="variablelist"><dt><a id="func-name"></a><span class="term">name</span></dt><dd>This is the name of the function, normally a symbol
   or a list of the form <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <em class="replaceable"><code>symbol</code></em>)</code>.
   It is used for printing the function and for error messages.
   This field is immutable.</dd><dt><a id="func-codevec"></a><span class="term"><a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">codevec</code></a></span></dt><dd>This is the byte-code vector, a <span class="type"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_unsigned-byte.html" target="_top"><code class="classname">UNSIGNED-BYTE</code></a> 8))</code></span>.
    This field is immutable.</dd><dt><span class="term"><a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[]</span></dt><dd>The remaining fields in the function object are
   references to other <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> objects.  These references are immutable,
   which is why they are called <span class="quote">“<span class="quote">constants</span>”</span>.
   (The referenced <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> objects can be mutable objects,
    such as <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_cons.html" target="_top"><code class="classname">CONS</code></a>es or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a>s, however.)
 </dd></dl></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">The Exception to the Immutability Rule</h3><p>When a generic function's dispatch code is installed, the <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">codevec</code></a>
  and <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a> fields are destructively modified.</p></div><p>Some of the <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a> can play special roles.
 A function looks like this, in more detail:
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term">name</span></dt><dd>see <a class="xref" href="#func-name">name</a>.
 </dd><dt><span class="term"><a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">codevec</code></a></span></dt><dd>see <a class="xref" href="#func-codevec"><code class="literal">codevec</code></a>.
 </dd><dt><span class="term"><a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">venv-const</code></a>*</span></dt><dd>At most one object, representing the closed-up
   variables, representing the variables of the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a> in
   which this function was defined.  It is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-vector.html" target="_top"><code class="classname">SIMPLE-VECTOR</code></a>, which
   looks like this: <span class="data"><code class="literal">#(<em class="replaceable"><code>next</code></em>
   <em class="replaceable"><code>value<sub>1</sub></code></em> ...
   <em class="replaceable"><code>value<sub>n</sub></code></em>)</code></span>
   where <em class="replaceable"><code>value<sub>1</sub></code></em>, ...,
   <em class="replaceable"><code>value<sub>n</sub></code></em>
   are the values of the closed-up variables,
   and <em class="replaceable"><code>next</code></em> is either <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> or a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-vector.html" target="_top"><code class="classname">SIMPLE-VECTOR</code></a> having the same
   structure.</dd><dt><span class="term"><a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">block-const</code></a>*</span></dt><dd>Objects representing closed-up <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_block.html" target="_top"><code class="function">BLOCK</code></a> tags,
   representing the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_block.html" target="_top"><code class="function">BLOCK</code></a> tags of the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a> in which
   this function was defined.  Each is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_cons.html" target="_top"><code class="classname">CONS</code></a> containing in the
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDR</code></a> part: either a frame pointer to the block frame, or <span class="data"><code class="literal">#&lt;DISABLED&gt;</code></span>.
   The <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CAR</code></a> is the block's name, for error messages only.
  </dd><dt><span class="term"><a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">tagbody-const</code></a>*</span></dt><dd>Objects representing closed-up <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_tagbody.html" target="_top"><code class="function">TAGBODY</code></a> tags,
   representing the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_tagbody.html" target="_top"><code class="function">TAGBODY</code></a> tags of the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a> in which
   this function was defined.  Each is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_cons.html" target="_top"><code class="classname">CONS</code></a> containing in the
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDR</code></a> part: either a frame pointer to the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_tagbody.html" target="_top"><code class="function">TAGBODY</code></a> frame, or
   <span class="data"><code class="literal">#&lt;DISABLED&gt;</code></span> if the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_tagbody.html" target="_top"><code class="function">TAGBODY</code></a> has already been left.  The <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CAR</code></a> is a
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-vector.html" target="_top"><code class="classname">SIMPLE-VECTOR</code></a> containing the names of the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_tagbody.html" target="_top"><code class="function">TAGBODY</code></a> tags,
   for error messages only.</dd><dt><span class="term"><a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">keyword-const</code></a>*</span></dt><dd>If the function was defined with a <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a>
   containing <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>, here come the symbols ("keywords"), in their
   correct order.  They are used by the interpreter during function call.
  </dd><dt><span class="term"><a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">other-const</code></a>*</span></dt><dd>Other objects needed by the function's bytecode.
  </dd></dl></div><p>
</p><p>If <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">venv-const</code></a>, <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">block-const</code></a>, <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">tagbody-const</code></a> are all absent,
the function is called <span class="emphasis"><em>autonomous</em></span>.
This is the case if the function does not refer to lexical variables,
blocks or tags defined in compile code outside of the function.
In particular, it is the case if the function is defined in a null
<a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a>.</p><p>If some <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">venv-const</code></a>, <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">block-const</code></a>, or <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">tagbody-const</code></a> are
present, the function (a <span class="quote">“<span class="quote">closure</span>”</span>) is created at runtime.
The compiler only generates a prototype, containing <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> values
instead of each <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">venv-const</code></a>, <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">block-const</code></a>, <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">tagbody-const</code></a>.
At runtime, a function is created by copying this prototype and
replacing the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> values by the definitive ones.</p><p>The list <span class="data"><code class="literal">(<a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">keyword-const</code></a>*
<a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">other-const</code></a>*)</code></span> normally does not contain duplicates, because
the compiler removes duplicates when possible.  (Duplicates can occur
nevertheless, through the use of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_load-time-value.html" target="_top"><code class="function">LOAD-TIME-VALUE</code></a>.)</p><p>The <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">codevec</code></a> looks like this
 (cf. the <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> type <span class="type">Codevec</span>):
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">spdepth_1</code> (2 bytes)</span></dt><dd>The 1st part of the maximal <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> depth.
 </dd><dt><span class="term"><code class="literal">spdepth_jmpbufsize</code> (2 bytes)</span></dt><dd>The <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a> part of the maximal <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> depth.
    The maximal <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> depth (precomputed by the compiler) is given by
    <code class="literal">spdepth_1 + spdepth_jmpbufsize * <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a></code>.
 </dd><dt><span class="term"><a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">numreq</code></a> (2 bytes)</span></dt><dd>Number of required parameters.
 </dd><dt><span class="term"><code class="literal">numopt</code> (2 bytes)</span></dt><dd>Number of optional parameters.
 </dd><dt><span class="term"><a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">flags</code></a> (1 byte)</span></dt><dd><div class="variablelist"><dl class="variablelist"><dt><span class="term">bit 0</span></dt><dd>set if the function has the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> parameter
    </dd><dt><span class="term">bit 7</span></dt><dd>set if the function has <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> parameters
    </dd><dt><span class="term">bit 6</span></dt><dd>set if the function has <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;ALLOW-OTHER-KEYS</code></a>
    </dd><dt><span class="term">bit 4</span></dt><dd>set if the function is a generic function
    </dd><dt><span class="term">bit 3</span></dt><dd>set if the function is a generic function and its
       effective method shall be returned (instead of being executed)
    </dd><dt><span class="term">bit 2</span></dt><dd>set if the full original <a class="link" href="#lalist" title="3.4. Lambda Lists sec_3-4">lambda list</a> is kept in the
       closure object, see <a class="xref" href="#space-decl" title="3.3.7. Declaration SPACE">Section 3.3.7, “Declaration <code class="literal">SPACE</code>”</a>
    </dd><dt><span class="term">bit 1</span></dt><dd>set if the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_doc_umentationcp.html" target="_top"><code class="function">FUNCTION</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/stagenfun_doc_umentationcp.html" target="_top"><code class="function">DOCUMENTATION</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>
       is kept in the closure object, see <a class="xref" href="#space-decl" title="3.3.7. Declaration SPACE">Section 3.3.7, “Declaration <code class="literal">SPACE</code>”</a>
  </dd></dl></div></dd><dt><span class="term"><code class="literal">signature</code> (1 byte)</span></dt><dd>An abbreviation code depending on
    <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">numreq</code></a>, <code class="literal">numopt</code>, <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">flags</code></a>.
    It is used for speeding up the function
    call.</dd><dt><span class="term"><code class="literal">numkey</code> (2 bytes, only if the
   function has <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>)</span></dt><dd>The number of <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> parameters.
 </dd><dt><span class="term"><code class="literal">keyconsts</code> (2 bytes, only if the
   function has <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>)</span></dt><dd>The offset of the <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">keyword-const</code></a> in the function.
 </dd><dt><span class="term"><code class="literal">byte</code>* (any number of bytes)</span></dt><dd>The bytecode instructions.
 </dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="instr-struct"></a>37.4. The general structure of the instructions</h2></div></div></div><p>All instructions consist of one byte, denoting the opcode, and
some number of operands.</p><p>The conversion from a byte (in the range 0..255) to the opcode is
performed by lookup in the table contained in the file <a class="link" href="#bytecode-d"><code class="filename">bytecode.d</code></a>.</p><p>There are the following types of operands, denoted by different
letters:
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>k</code></em>, <em class="replaceable"><code>n</code></em>, <em class="replaceable"><code>m</code></em>, <em class="replaceable"><code>l</code></em></span></dt><dd>A (nonnegative) numeric operand.
   The next byte is read.
   If its bit 7 is zero, then the bits 6..0 give the value (7 bits).
   If its bit 7 is one, then the bits 6..0 and the subsequent byte
   together form the value (15 bits).
  </dd><dt><span class="term"><em class="replaceable"><code>b</code></em></span></dt><dd>A (nonnegative) 1-byte operand.
   The next byte is read and is the value.
  </dd><dt><span class="term"><em class="replaceable"><code>label</code></em></span></dt><dd>A label operand.
   A signed numeric operand is read: The next byte is read.
   If its bit 7 is zero, then the bits 6..0 give the value
    (7 bits, sign-extended).
   If its bit 7 is one, then the bits 6..0 and the subsequent byte
    together form the value (15 bits, sign-extended).
   If the latter 15-bit result is zero, then four more bytes are read
    and put together (32 bits, sign-extended).
   Finally, the bytecode pointer for the target is computed as the
   current bytecode pointer (pointing after the operand just read), plus
   the signed numeric operand.
  </dd></dl></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="instr-set"></a>37.5. The instruction set</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#instr-const">37.5.1. Instructions for constants</a></span></dt><dt><span class="section"><a href="#instr-lex-var">37.5.2. Instructions for lexical variables</a></span></dt><dt><span class="section"><a href="#instr-dyn-var">37.5.3. Instructions for dynamic variables</a></span></dt><dt><span class="section"><a href="#instr-stack">37.5.4. Instructions for stack operations</a></span></dt><dt><span class="section"><a href="#instr-jump">37.5.5. Instructions for control flow, jumps</a></span></dt><dt><span class="section"><a href="#instr-env">37.5.6. Instructions for lexical environment,    creation of closures</a></span></dt><dt><span class="section"><a href="#instr-funcall">37.5.7. Instructions for function calls</a></span></dt><dt><span class="section"><a href="#instr-optkey">37.5.8. Instructions for optional   and keyword parameters</a></span></dt><dt><span class="section"><a href="#instr-mulval">37.5.9. Instructions for multiple values</a></span></dt><dt><span class="section"><a href="#instr-block">37.5.10. Instructions for    <code class="function">BLOCK</code> and <code class="function">RETURN-FROM</code></a></span></dt><dt><span class="section"><a href="#instr-tagbody">37.5.11. Instructions for <code class="function">TAGBODY</code> and <code class="function">GO</code></a></span></dt><dt><span class="section"><a href="#instr-catch">37.5.12. Instructions for <code class="function">CATCH</code> and <code class="function">THROW</code></a></span></dt><dt><span class="section"><a href="#instr-unwind">37.5.13. Instructions for <code class="function">UNWIND-PROTECT</code></a></span></dt><dt><span class="section"><a href="#instr-handler">37.5.14. Instructions for <code class="function">HANDLER-BIND</code></a></span></dt><dt><span class="section"><a href="#instr-inline">37.5.15. Instructions for some inlined   functions</a></span></dt><dt><span class="section"><a href="#instr-combo">37.5.16. Combined instructions</a></span></dt><dt><span class="section"><a href="#instr-shortcut">37.5.17. Shortcut instructions</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="instr-const"></a>37.5.1. Instructions for constants</h3></div></div></div><div class="informaltable"><a id="instr-const-tab"></a><table class="informaltable" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">mnemonic</th><th align="center">description</th><th align="center">semantics</th></tr></thead><tbody><tr><td align="center"><span class="byte"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>)</code></span></td><td align="center">Load <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td><td align="center"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1</td></tr><tr><td align="center"><span class="byte"><code class="literal">(PUSH-NIL <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Push <em class="replaceable"><code>n</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>s into the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>.</td><td align="center"><em class="replaceable"><code>n</code></em> times do: *--<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>,
             Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>)</code></span></td><td align="center">Load <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td><td align="center"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>, <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1</td></tr><tr><td align="center"><span class="byte"><code class="literal">(CONST <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Load the function's <em class="replaceable"><code>n</code></em>th constant into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td><td align="center"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[<em class="replaceable"><code>n</code></em>],
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1</td></tr></tbody></table></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="instr-lex-var"></a>37.5.2. Instructions for lexical variables</h3></div></div></div><div class="informaltable"><a id="instr-lex-var-tab"></a><table class="informaltable" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">mnemonic</th><th align="center">description</th><th align="center">semantics</th></tr></thead><tbody><tr><td align="center"><span class="byte"><code class="literal">(LOAD <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Load a directly accessible local variable into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td><td align="center"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>),
         <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1</td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOADI <em class="replaceable"><code>k<sub>1</sub></code></em> <em class="replaceable"><code>k<sub>2</sub></code></em> <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Load an indirectly accessible local variable into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td><td align="center"><em class="replaceable"><code>k</code></em> := <em class="replaceable"><code>k<sub>1</sub></code></em> + <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a> * <em class="replaceable"><code>k<sub>2</sub></code></em>,
         <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := *(*(<a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a>+<em class="replaceable"><code>k</code></em>)+ <em class="replaceable"><code>n</code></em>),
         <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1</td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOADC <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>m</code></em>)</code></span></td><td align="center">Load a closed-up variable, defined in the same function and
         directly accessible, into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td><td align="center"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_svref.html" target="_top"><code class="function">SVREF</code></a>(*(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>),1+<em class="replaceable"><code>m</code></em>),
         <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1</td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOADV <em class="replaceable"><code>k</code></em> <em class="replaceable"><code>m</code></em>)</code></span></td><td align="center">Load a closed-up variable, defined in an outer function,
         into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td><td align="center"><em class="replaceable"><code>v</code></em> := <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">venv-const</code></a>,
         <em class="replaceable"><code>m</code></em> times do: <em class="replaceable"><code>v</code></em> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_svref.html" target="_top"><code class="function">SVREF</code></a>(<em class="replaceable"><code>v</code></em>,0),
         <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_svref.html" target="_top"><code class="function">SVREF</code></a>(<em class="replaceable"><code>v</code></em>,<em class="replaceable"><code>m</code></em>),
         <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1</td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOADIC <em class="replaceable"><code>k<sub>1</sub></code></em> <em class="replaceable"><code>k<sub>2</sub></code></em> <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>m</code></em>)</code></span></td><td align="center">Load a closed-up variable, defined in the same function and
             indirectly accessible, into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td><td align="center"><em class="replaceable"><code>k</code></em> := <em class="replaceable"><code>k<sub>1</sub></code></em> + <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a> * <em class="replaceable"><code>k<sub>2</sub></code></em>,
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_svref.html" target="_top"><code class="function">SVREF</code></a>(*(*(<a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a>+<em class="replaceable"><code>k</code></em>)+<em class="replaceable"><code>n</code></em>),1+<em class="replaceable"><code>m</code></em>),
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1</td></tr><tr><td align="center"><span class="byte"><code class="literal">(STORE <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Store values into a directly accessible local variable.</td><td align="center">*(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>) := <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>,
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1</td></tr><tr><td align="center"><span class="byte"><code class="literal">(STOREI <em class="replaceable"><code>k<sub>1</sub></code></em> <em class="replaceable"><code>k<sub>2</sub></code></em> <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Store values into an indirectly accessible local variable.</td><td align="center"><em class="replaceable"><code>k</code></em> := <em class="replaceable"><code>k<sub>1</sub></code></em> + <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a> * <em class="replaceable"><code>k<sub>2</sub></code></em>,
              *(*(<a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a>+<em class="replaceable"><code>k</code></em>)+ <em class="replaceable"><code>n</code></em>) := <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>,
              <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1</td></tr><tr><td align="center"><span class="byte"><code class="literal">(STOREC <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>m</code></em>)</code></span></td><td align="center">Store values into a closed-up variable, defined in the same
             function and directly accessible.</td><td align="center"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_svref.html" target="_top"><code class="function">SVREF</code></a>(*(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>),1+m) := <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>,
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1</td></tr><tr><td align="center"><span class="byte"><code class="literal">(STOREV <em class="replaceable"><code>k</code></em> <em class="replaceable"><code>m</code></em>)</code></span></td><td align="center">Store values into a closed-up variable, defined in an outer
             function.</td><td align="center"><em class="replaceable"><code>v</code></em> := <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">venv-const</code></a>,
             <em class="replaceable"><code>m</code></em> times do: <em class="replaceable"><code>v</code></em> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_svref.html" target="_top"><code class="function">SVREF</code></a>(<em class="replaceable"><code>v</code></em>,0),
             <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_svref.html" target="_top"><code class="function">SVREF</code></a>(<em class="replaceable"><code>v</code></em>,<em class="replaceable"><code>m</code></em>) := <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>,
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1</td></tr><tr><td align="center"><span class="byte"><code class="literal">(STOREIC <em class="replaceable"><code>k<sub>1</sub></code></em> <em class="replaceable"><code>k<sub>2</sub></code></em> <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>m</code></em>)</code></span></td><td align="center">Store values into a closed-up variable, defined in the same
             function and indirectly accessible.</td><td align="center"><em class="replaceable"><code>k</code></em> := <em class="replaceable"><code>k<sub>1</sub></code></em> + <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a> * <em class="replaceable"><code>k<sub>2</sub></code></em>,
             <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_svref.html" target="_top"><code class="function">SVREF</code></a>(*(*(<a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a>+<em class="replaceable"><code>k</code></em>)+<em class="replaceable"><code>n</code></em>),1+<em class="replaceable"><code>m</code></em>) := <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>,
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1</td></tr></tbody></table></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="instr-dyn-var"></a>37.5.3. Instructions for dynamic variables</h3></div></div></div><div class="informaltable"><a id="instr-dyn-var-tab"></a><table class="informaltable" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">mnemonic</th><th align="center">description</th><th align="center">semantics</th></tr></thead><tbody><tr><td align="center"><span class="byte"><code class="literal">(GETVALUE <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Load a symbol's value into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td><td align="center"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := symbol-value(<a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[<em class="replaceable"><code>n</code></em>]),
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1</td></tr><tr><td align="center"><span class="byte"><code class="literal">(SETVALUE <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Store values into a symbol's value.</td><td align="center">symbol-value(<a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[<em class="replaceable"><code>n</code></em>]) := <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>,
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1</td></tr><tr><td align="center"><span class="byte"><code class="literal">(BIND <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Bind a symbol dynamically.</td><td align="center">Bind the value of the symbol
             <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[<em class="replaceable"><code>n</code></em>] to <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>,
             implicitly <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> -= 3,
             Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(UNBIND1)</code></span></td><td align="center">Dissolve one binding frame.</td><td align="center">Unbind the binding frame <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> is pointing to,
             implicitly <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> += 3</td></tr><tr><td align="center"><span class="byte"><code class="literal">(UNBIND <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Dissolve <em class="replaceable"><code>n</code></em> binding frames.</td><td align="center"><em class="replaceable"><code>n</code></em> times do:
              Unbind the binding frame <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> is pointing to, thereby
              incrementing <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>
             Thus, <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> += 1+2*<em class="replaceable"><code>n</code></em></td></tr><tr><td align="center"><span class="byte"><code class="literal">(PROGV)</code></span></td><td align="center">Bind a set of symbols dynamically to a set of values.</td><td align="center"><em class="replaceable"><code>symbols</code></em> := *<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>++,
             *--<a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> := <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>,
             build a single binding frame binding the symbols in
             <em class="replaceable"><code>symbols</code></em> to the values in <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>,
             Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr></tbody></table></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="instr-stack"></a>37.5.4. Instructions for stack operations</h3></div></div></div><div class="informaltable"><a id="instr-stack-tab"></a><table class="informaltable" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">mnemonic</th><th align="center">description</th><th align="center">semantics</th></tr></thead><tbody><tr><td align="center"><span class="byte"><code class="literal">(PUSH)</code></span></td><td align="center">Push one object onto the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>.</td><td align="center">*--<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>,
             Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(POP)</code></span></td><td align="center">Pop one object from the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>, into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td><td align="center"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := *<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>++, <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1</td></tr><tr><td align="center"><span class="byte"><code class="literal">(SKIP <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Restore a previous <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> pointer.
             Remove <em class="replaceable"><code>n</code></em> objects from the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>.</td><td align="center"><a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> + <em class="replaceable"><code>n</code></em></td></tr><tr><td align="center"><span class="byte"><code class="literal">(SKIPI <em class="replaceable"><code>k<sub>1</sub></code></em> <em class="replaceable"><code>k<sub>2</sub></code></em> <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Restore a previous <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> pointer. Remove an unknown
             number of objects from the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>.</td><td align="center"><em class="replaceable"><code>k</code></em> := <em class="replaceable"><code>k<sub>1</sub></code></em> + <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a> * <em class="replaceable"><code>k<sub>2</sub></code></em>,
             <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := *(<a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a>+<em class="replaceable"><code>k</code></em>),
             <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> := <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a>+<em class="replaceable"><code>k</code></em>+1,
             <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> + <em class="replaceable"><code>n</code></em></td></tr><tr><td align="center"><span class="byte"><code class="literal">(SKIPSP <em class="replaceable"><code>k<sub>1</sub></code></em> <em class="replaceable"><code>k<sub>2</sub></code></em>)</code></span></td><td align="center">Restore a previous <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> pointer.</td><td align="center"><em class="replaceable"><code>k</code></em> := <em class="replaceable"><code>k<sub>1</sub></code></em> + <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a> * <em class="replaceable"><code>k<sub>2</sub></code></em>,
             <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> := <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a>+<em class="replaceable"><code>k</code></em></td></tr></tbody></table></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="instr-jump"></a>37.5.5. Instructions for control flow, jumps</h3></div></div></div><div class="informaltable"><a id="instr-jump-tab"></a><table class="informaltable" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">mnemonic</th><th align="center">description</th><th align="center">semantics</th></tr></thead><tbody><tr><td align="center"><span class="byte"><code class="literal">(SKIP&amp;RET <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Clean up the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>, and return from the function.</td><td align="center"><a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>,
            return from the function, returning values.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(SKIP&amp;RETGF <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Clean up the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>, and return from the generic
             function.</td><td align="center">If bit 3 is set in the function's <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">flags</code></a>,
                then <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>, <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1,
                     and return from the function.
             Otherwise: if the current function has no <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> argument,
                then <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>-<a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">numreq</code></a>,
                     apply <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> to the <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">numreq</code></a> arguments
                           still on the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>, and
                           return from the function.
                Else <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>-<a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">numreq</code></a>-1,
                     apply <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> to the <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">numreq</code></a> arguments and the
                           <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a> argument, all still on the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>, and
                           return from the function.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(JMP <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Jump to <em class="replaceable"><code>label</code></em>.</td><td align="center">PC := <em class="replaceable"><code>label</code></em>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(JMPIF <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Jump to <em class="replaceable"><code>label</code></em>, if <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> is true.</td><td align="center">If <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> is not <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, PC := <em class="replaceable"><code>label</code></em>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(JMPIFNOT <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Jump to <em class="replaceable"><code>label</code></em>, if <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> is false.</td><td align="center">If <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, PC := <em class="replaceable"><code>label</code></em>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(JMPIF1 <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Jump to <em class="replaceable"><code>label</code></em> and forget secondary values,
             if <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> is true.</td><td align="center">If <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> is not <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>,
                <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1, PC := <em class="replaceable"><code>label</code></em>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(JMPIFNOT1 <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Jump to <em class="replaceable"><code>label</code></em> and forget secondary values,
             if <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> is false.</td><td align="center">If <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>,
                <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1, PC := <em class="replaceable"><code>label</code></em>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(JMPIFATOM <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Jump to <em class="replaceable"><code>label</code></em>, if <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> is not a cons.</td><td align="center">If <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> is not a cons, PC := <em class="replaceable"><code>label</code></em>.
             Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(JMPIFCONSP <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Jump to <em class="replaceable"><code>label</code></em>, if <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> is a cons.</td><td align="center">If <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> is a cons, PC := <em class="replaceable"><code>label</code></em>.
                Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(JMPIFEQ <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Jump to <em class="replaceable"><code>label</code></em>, if <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a> to the top-of-stack.</td><td align="center">If eq(<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>,*<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>++), PC := <em class="replaceable"><code>label</code></em>.
             Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(JMPIFNOTEQ <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Jump to <em class="replaceable"><code>label</code></em>, if <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> is not <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a>
             to the top-of-stack.</td><td align="center">If not eq(<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>,*<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>++), PC := <em class="replaceable"><code>label</code></em>.
             Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(JMPIFEQTO <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Jump to <em class="replaceable"><code>label</code></em>,
             if the top-of-stack is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a> to a constant.</td><td align="center">If eq(*<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>++,<a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[<em class="replaceable"><code>n</code></em>]), PC := <em class="replaceable"><code>label</code></em>.
             Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(JMPIFNOTEQTO <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Jump to <em class="replaceable"><code>label</code></em>, if the top-of-stack is not <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a>
             to a constant.</td><td align="center">If not eq(*<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>++,<a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[<em class="replaceable"><code>n</code></em>]), PC := <em class="replaceable"><code>label</code></em>.
             Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(JMPHASH <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Table-driven jump, depending on <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>.</td><td align="center">Lookup <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> in the hash table <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[<em class="replaceable"><code>n</code></em>].
             (The hash table's test is either <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eql.html" target="_top"><code class="function">EQL</code></a>.)
             If found, the hash table value is a signed <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_fixnum.html" target="_top"><code class="classname">FIXNUM</code></a>,
             jump to it: PC := PC + value.  Else jump to <em class="replaceable"><code>label</code></em>.
             Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(JMPHASHV <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Table-driven jump, depending on <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>,
             inside a generic function.</td><td align="center">Lookup <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> in the hash table <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_svref.html" target="_top"><code class="function">SVREF</code></a>(<a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[0],<em class="replaceable"><code>n</code></em>).
             (The hash table's test is either <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eql.html" target="_top"><code class="function">EQL</code></a>.)
             If found, the hash table value is a signed <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_fixnum.html" target="_top"><code class="classname">FIXNUM</code></a>,
             jump to it: PC := PC + value.  Else jump to <em class="replaceable"><code>label</code></em>.
             Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(JSR <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Subroutine call.</td><td align="center">*--<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := function. Then start interpreting the
             bytecode at <em class="replaceable"><code>label</code></em>, with <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a> undefined.
             When a <span class="byte"><code class="literal">(RET)</code></span> is encountered,
             program execution is resumed at the instruction after
             <span class="byte"><code class="literal">(JSR <em class="replaceable"><code>label</code></em>)</code></span>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(JMPTAIL <em class="replaceable"><code>m</code></em> <em class="replaceable"><code>n</code></em>
             <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Tail subroutine call.</td><td align="center"><em class="replaceable"><code>n</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eqcm_sleq__lteqcm_gteq.html" target="_top"><code class="function">&gt;=</code></a> <em class="replaceable"><code>m</code></em>.
             The <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> frame of size <em class="replaceable"><code>n</code></em> is reduced to size <em class="replaceable"><code>m</code></em>:
             {*(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>-<em class="replaceable"><code>m</code></em>), ..., *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>-1)} :=
               {*<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>, ..., *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>m</code></em>-1)}.
             <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> += n-m.
             *--<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := function.
             Then jump to <em class="replaceable"><code>label</code></em>, with <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a> undefined.</td></tr></tbody></table></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="instr-env"></a>37.5.6. Instructions for <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a>,
   creation of closures</h3></div></div></div><div class="informaltable"><a id="instr-env-tab"></a><table class="informaltable" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">mnemonic</th><th align="center">description</th><th align="center">semantics</th></tr></thead><tbody><tr><td align="center"><span class="byte"><code class="literal">(VENV)</code></span></td><td align="center">Load the <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">venv-const</code></a> into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td><td align="center"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[0], <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(MAKE-VECTOR1&amp;PUSH <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Create a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-vector.html" target="_top"><code class="classname">SIMPLE-VECTOR</code></a> used for closed-up variables.</td><td align="center"><em class="replaceable"><code>v</code></em> := new <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-vector.html" target="_top"><code class="classname">SIMPLE-VECTOR</code></a> of size <em class="replaceable"><code>n</code></em>+1.
             <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_svref.html" target="_top"><code class="function">SVREF</code></a>(<em class="replaceable"><code>v</code></em>,0) := <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>.
             *--<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := <em class="replaceable"><code>v</code></em>. Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(COPY-CLOSURE <em class="replaceable"><code>m</code></em> <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Create a closure by copying the prototype and filling in
             the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-1-1-3.html">lexical environment</a>.</td><td align="center"><em class="replaceable"><code>f</code></em> := copy-function(<a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[<em class="replaceable"><code>m</code></em>]).
             For <em class="replaceable"><code>i</code></em>=0,..,<em class="replaceable"><code>n</code></em>-1:
                 <em class="replaceable"><code>f</code></em>_<a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[i] := *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>-1-<em class="replaceable"><code>i</code></em>).
             <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> += <em class="replaceable"><code>n</code></em>.
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <em class="replaceable"><code>f</code></em>, <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1</td></tr></tbody></table></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="instr-funcall"></a>37.5.7. Instructions for function calls</h3></div></div></div><div class="informaltable"><a id="instr-funcall-tab"></a><table class="informaltable" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">mnemonic</th><th align="center">description</th><th align="center">semantics</th></tr></thead><tbody><tr><td align="center"><span class="byte"><code class="literal">(CALL <em class="replaceable"><code>k</code></em> <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Calls a constant function with <em class="replaceable"><code>k</code></em> arguments.</td><td align="center">The function <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[<em class="replaceable"><code>n</code></em>] is called
             with the arguments *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>k</code></em>-1), ..., *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+0).
             <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> += <em class="replaceable"><code>k</code></em>. The returned values go into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALL0 <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Calls a constant function with 0 arguments.</td><td align="center">The function <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[<em class="replaceable"><code>n</code></em>] is called with 0 arguments.
             The returned values go into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALL1 <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Calls a constant function with 1 argument.</td><td align="center">The function <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[<em class="replaceable"><code>n</code></em>] is called with one argument *<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>.
             <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> += 1. The returned values go into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALL2 <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Calls a constant function with 2 arguments.</td><td align="center">The function <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[<em class="replaceable"><code>n</code></em>] is called
             with two arguments *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+1) and *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+0).
             <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> += 2. The returned values go into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALLS1 <em class="replaceable"><code>b</code></em>)</code></span></td><td align="center">Calls a system function with no <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a>.</td><td align="center">Calls the system function <a class="link" href="#byte-version" title="Warning"><code class="varname">FUNTAB</code></a>[<em class="replaceable"><code>b</code></em>].
             The right number of arguments is already on the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>
             (including <span class="data"><code class="literal">#&lt;UNBOUND&gt;</code></span>s in place of absent <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> or
              <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> parameters).
             The arguments are removed from the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>. The returned values go into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALLS2 <em class="replaceable"><code>b</code></em>)</code></span></td><td align="center">Calls a system function with no <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a>.</td><td align="center">Calls the system function <a class="link" href="#byte-version" title="Warning"><code class="varname">FUNTAB</code></a>[256+<em class="replaceable"><code>b</code></em>].
             The right number of arguments is already on the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>
             (including <span class="data"><code class="literal">#&lt;UNBOUND&gt;</code></span>s in place of absent <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a> or
              <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> parameters).
             The arguments are removed from the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>. The returned values go into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALLSR <em class="replaceable"><code>m</code></em> <em class="replaceable"><code>b</code></em>)</code></span></td><td align="center">Calls a system function with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;REST</code></a>.</td><td align="center">Calls the system function <a class="link" href="#byte-version" title="Warning"><code class="varname">FUNTAB</code></a>R[<em class="replaceable"><code>b</code></em>].
             The minimum number of arguments is already on the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>,
             and <em class="replaceable"><code>m</code></em> additional arguments as well.
             The arguments are removed from the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>. The returned values go into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALLC)</code></span></td><td align="center">Calls a computed compiled function with no <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>s.</td><td align="center">Calls the compiled function <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>.
             The right number of arguments is already on the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>
             (including <span class="data"><code class="literal">#&lt;UNBOUND&gt;</code></span>s in place of absent <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
              parameters).
             The arguments are removed from the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>. The returned values go into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALLCKEY)</code></span></td><td align="center">Calls a computed compiled function with <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a>s.</td><td align="center">Calls the compiled function <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>.
             The right number of arguments is already on the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>
             (including <span class="data"><code class="literal">#&lt;UNBOUND&gt;</code></span>s in place of absent <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;OPTIONAL</code></a>
              or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_3-4-1.html" target="_top"><code class="literal">&amp;KEY</code></a> parameters).
             The arguments are removed from the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>. The returned values go into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(FUNCALL <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Calls a computed function.</td><td align="center">Calls the function *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>)
             with the arguments *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>-1), ..., *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+0).
             <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> += <em class="replaceable"><code>n</code></em>+1. The returned values go into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(APPLY <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Calls a computed function with an unknown number of arguments.</td><td align="center">Calls the function *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>)
         with the arguments *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>-1), ..., *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+0)
         and a list of additional arguments <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>.
         <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> += <em class="replaceable"><code>n</code></em>+1. The returned values go into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr></tbody></table></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="instr-optkey"></a>37.5.8. Instructions for optional
  and keyword parameters</h3></div></div></div><div class="informaltable"><a id="instr-optkey-tab"></a><table class="informaltable" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">mnemonic</th><th align="center">description</th><th align="center">semantics</th></tr></thead><tbody><tr><td align="center"><span class="byte"><code class="literal">(PUSH-UNBOUND <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Push <em class="replaceable"><code>n</code></em> <span class="data"><code class="literal">#&lt;UNBOUND&gt;</code></span>s into the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>.</td><td align="center"><em class="replaceable"><code>n</code></em> times do: *--<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := <span class="data"><code class="literal">#&lt;UNBOUND&gt;</code></span>.
             Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(UNLIST <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>m</code></em>)</code></span></td><td align="center">Destructure a proper <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>.</td><td align="center">0 ≤ <em class="replaceable"><code>m</code></em> ≤ <em class="replaceable"><code>n</code></em>.
             <em class="replaceable"><code>n</code></em> times do: *--<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CAR</code></a>(<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>),
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDR</code></a>(<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>).
             During the last <em class="replaceable"><code>m</code></em> iterations, the list <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>
             may already have reached its end;
             in this case, *--<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := <span class="data"><code class="literal">#&lt;UNBOUND&gt;</code></span>.
             At the end, <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> must be <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
             Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(UNLIST* <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>m</code></em>)</code></span></td><td align="center">Destructure a proper or dotted <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>.</td><td align="center">0 ≤ <em class="replaceable"><code>m</code></em> ≤ <em class="replaceable"><code>n</code></em>, <em class="replaceable"><code>n</code></em> &gt; 0.
             <em class="replaceable"><code>n</code></em> times do: *--<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CAR</code></a>(<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>),
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDR</code></a>(<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>).
             During the last <em class="replaceable"><code>m</code></em> iterations, the list <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>
             may already have reached its end;
             in this case, *--<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := <span class="data"><code class="literal">#&lt;UNBOUND&gt;</code></span>.
             At the end, after <em class="replaceable"><code>n</code></em> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDR</code></a>s, *--<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>.
             Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(JMPIFBOUNDP <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Jump to <em class="replaceable"><code>label</code></em>, if a local variable is not unbound.</td><td align="center">If *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>) is not <span class="data"><code class="literal">#&lt;UNBOUND&gt;</code></span>,
                <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>), <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1, PC := <em class="replaceable"><code>label</code></em>.
             Else: Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>..</td></tr><tr><td align="center"><span class="byte"><code class="literal">(BOUNDP <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Load <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a> or <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>, depending on whether a local
             variable is bound.</td><td align="center">If *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>) is not <span class="data"><code class="literal">#&lt;UNBOUND&gt;</code></span>,
                <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>, <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1.
             Else: <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(UNBOUND-&gt;NIL <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">If a local variable is unbound, assign a default value
             <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> to it.</td><td align="center">If *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>) is <span class="data"><code class="literal">#&lt;UNBOUND&gt;</code></span>,
             *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>) := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.</td></tr></tbody></table></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="instr-mulval"></a>37.5.9. Instructions for <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_m.html#multiple_values">multiple values</a></h3></div></div></div><div class="informaltable"><a id="instr-mulval-tab"></a><table class="informaltable" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">mnemonic</th><th align="center">description</th><th align="center">semantics</th></tr></thead><tbody><tr><td align="center"><span class="byte"><code class="literal">(VALUES0)</code></span></td><td align="center">Load no values into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td><td align="center"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 0</td></tr><tr><td align="center"><span class="byte"><code class="literal">(VALUES1)</code></span></td><td align="center">Forget secondary values.</td><td align="center"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1</td></tr><tr><td align="center"><span class="byte"><code class="literal">(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>-TO-MV <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Pop the first <em class="replaceable"><code>n</code></em> objects from <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td><td align="center">Load values(*(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>-1),...,*(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+0)) into
             values. <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> += <em class="replaceable"><code>n</code></em>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(MV-TO-<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>)</code></span></td><td align="center">Save values on <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>.</td><td align="center">Push the <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> values onto the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>
             (in order: <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> comes first).
             <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> -= <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a>. Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(NV-TO-<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Save <em class="replaceable"><code>n</code></em> values on <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>.</td><td align="center">Push the first <em class="replaceable"><code>n</code></em> values onto the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>
             (in order: <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> comes first).
             <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> -= <em class="replaceable"><code>n</code></em>. Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(MV-TO-LIST)</code></span></td><td align="center">Convert <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_m.html#multiple_values">multiple values</a> into a list.</td><td align="center"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := list of values, <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1</td></tr><tr><td align="center"><span class="byte"><code class="literal">(LIST-TO-MV)</code></span></td><td align="center">Convert a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a> into <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_m.html#multiple_values">multiple values</a>.</td><td align="center">Call the function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_values-list.html" target="_top"><code class="function">VALUES-LIST</code></a> with <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> as argument.
             The returned values go into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(MVCALLP)</code></span></td><td align="center">Start a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_multiple-value-call.html" target="_top"><code class="function">MULTIPLE-VALUE-CALL</code></a> invocation.</td><td align="center">*--<a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> := <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>. *--<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(MVCALL)</code></span></td><td align="center">Finish a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_multiple-value-call.html" target="_top"><code class="function">MULTIPLE-VALUE-CALL</code></a> invocation.</td><td align="center">newSTACK := *<a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a>++.
             Call the function *(newSTACK-1), passing it
             *(newSTACK-2), ..., *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+0) as arguments.
             <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := newSTACK. The returned values go into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr></tbody></table></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="instr-block"></a>37.5.10. Instructions for
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_block.html" target="_top"><code class="function">BLOCK</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_return-from.html" target="_top"><code class="function">RETURN-FROM</code></a></h3></div></div></div><div class="informaltable"><a id="instr-block-tab"></a><table class="informaltable" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">mnemonic</th><th align="center">description</th><th align="center">semantics</th></tr></thead><tbody><tr><td align="center"><span class="byte"><code class="literal">(BLOCK-OPEN <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Create a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_block.html" target="_top"><code class="function">BLOCK</code></a> frame.</td><td align="center">Create a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_block.html" target="_top"><code class="function">BLOCK</code></a> frame, <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> -= 3, <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> -= 2+<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a>.
   The topmost (third) object in the block frame is
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_cons.html" target="_top"><code class="function">CONS</code></a>(<a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[<em class="replaceable"><code>n</code></em>],frame-pointer) (its <em class="replaceable"><code>block-cons</code></em>).
   Upon a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_return-from.html" target="_top"><code class="function">RETURN-FROM</code></a> to this frame, execution will continue at <em class="replaceable"><code>label</code></em>.
   Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>..</td></tr><tr><td align="center"><span class="byte"><code class="literal">(BLOCK-CLOSE)</code></span></td><td align="center">Dissolve a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_block.html" target="_top"><code class="function">BLOCK</code></a> frame.</td><td align="center">Dissolve the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_block.html" target="_top"><code class="function">BLOCK</code></a> frame at <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>, <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> += 3,
             <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> += 2+<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a>. Mark the <em class="replaceable"><code>block-cons</code></em> as invalid.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(RETURN-FROM <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Leave a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_block.html" target="_top"><code class="function">BLOCK</code></a> whose <em class="replaceable"><code>block-cons</code></em> is given.</td><td align="center"><em class="replaceable"><code>block-cons</code></em> := <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[<em class="replaceable"><code>n</code></em>].
             If <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDR</code></a>(<em class="replaceable"><code>block-cons</code></em>) = <span class="data"><code class="literal">#&lt;DISABLED&gt;</code></span>, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.
             Else <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDR</code></a>(<em class="replaceable"><code>block-cons</code></em>) is a frame-pointer.
             Unwind the stack up to this frame, pass it values.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(RETURN-FROM-I <em class="replaceable"><code>k<sub>1</sub></code></em> <em class="replaceable"><code>k<sub>2</sub></code></em> <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Leave a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_block.html" target="_top"><code class="function">BLOCK</code></a> whose <em class="replaceable"><code>block-cons</code></em> is indirectly accessible.</td><td align="center"><em class="replaceable"><code>k</code></em> := <em class="replaceable"><code>k<sub>1</sub></code></em> + <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a> * <em class="replaceable"><code>k<sub>2</sub></code></em>,
             <em class="replaceable"><code>block-cons</code></em> := *(*(<a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a>+<em class="replaceable"><code>k</code></em>)+<em class="replaceable"><code>n</code></em>).
             If <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDR</code></a>(<em class="replaceable"><code>block-cons</code></em>) = <span class="data"><code class="literal">#&lt;DISABLED&gt;</code></span>, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.
             Else <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDR</code></a>(<em class="replaceable"><code>block-cons</code></em>) is a frame-pointer.
             Unwind the stack up to this frame, pass it values.</td></tr></tbody></table></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="instr-tagbody"></a>37.5.11. Instructions for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_tagbody.html" target="_top"><code class="function">TAGBODY</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_go.html" target="_top"><code class="function">GO</code></a></h3></div></div></div><div class="informaltable"><a id="instr-tagbody-tab"></a><table class="informaltable" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">mnemonic</th><th align="center">description</th><th align="center">semantics</th></tr></thead><tbody><tr><td align="center"><span class="byte"><code class="literal">(TAGBODY-OPEN <em class="replaceable"><code>m</code></em>
             <em class="replaceable"><code>label<sub>1</sub></code></em> ...
             <em class="replaceable"><code>label<sub>n</sub></code></em>)</code></span></td><td align="center">Create a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_tagbody.html" target="_top"><code class="function">TAGBODY</code></a> frame.</td><td align="center">Fetch <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[<em class="replaceable"><code>m</code></em>], this is a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/typ_simple-vector.html" target="_top"><code class="classname">SIMPLE-VECTOR</code></a> with
             <em class="replaceable"><code>n</code></em> elements, then decode <em class="replaceable"><code>n</code></em> label operands.
             Create a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_tagbody.html" target="_top"><code class="function">TAGBODY</code></a> frame, <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> -= 3+<em class="replaceable"><code>n</code></em>, <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> -= 1+<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a>.
             The third object in the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_tagbody.html" target="_top"><code class="function">TAGBODY</code></a> frame is
             <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_cons.html" target="_top"><code class="function">CONS</code></a>(<a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[<em class="replaceable"><code>m</code></em>],frame-pointer) (the <em class="replaceable"><code>tagbody-cons</code></em>)
             Upon a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_go.html" target="_top"><code class="function">GO</code></a> to tag <em class="replaceable"><code>label</code></em> of this frame, execution
             will continue at <em class="replaceable"><code>label<sub>l</sub></code></em>.
             Invalidate <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(TAGBODY-CLOSE-NIL)</code></span></td><td align="center">Dissolve a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_tagbody.html" target="_top"><code class="function">TAGBODY</code></a> frame, and load <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.</td><td align="center">Dissolve the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_tagbody.html" target="_top"><code class="function">TAGBODY</code></a> frame at <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>,
             <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> += 3+<em class="replaceable"><code>m</code></em>, <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> += 1+<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a>.
             Mark the <em class="replaceable"><code>tagbody-cons</code></em> as invalid.
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>, <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(TAGBODY-CLOSE)</code></span></td><td align="center">Dissolve a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_tagbody.html" target="_top"><code class="function">TAGBODY</code></a> frame.</td><td align="center">Dissolve the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_tagbody.html" target="_top"><code class="function">TAGBODY</code></a> frame at <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>,
             <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> += 3+<em class="replaceable"><code>m</code></em>, <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> += 1+<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a>.
             Mark the <em class="replaceable"><code>tagbody-cons</code></em> as invalid.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(GO <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Jump into a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_tagbody.html" target="_top"><code class="function">TAGBODY</code></a> whose <em class="replaceable"><code>tagbody-cons</code></em> is given.</td><td align="center"><em class="replaceable"><code>tagbody-cons</code></em> := <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[<em class="replaceable"><code>n</code></em>].
             If <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDR</code></a>(<em class="replaceable"><code>tagbody-cons</code></em>) = <span class="data"><code class="literal">#&lt;DISABLED&gt;</code></span>, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.
             Else <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDR</code></a>(<em class="replaceable"><code>tagbody-cons</code></em>) is a frame-pointer. Unwind the stack up
             to this frame, pass it the number <em class="replaceable"><code>label</code></em>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(GO-I <em class="replaceable"><code>k<sub>1</sub></code></em> <em class="replaceable"><code>k<sub>2</sub></code></em> <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Jump into a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_tagbody.html" target="_top"><code class="function">TAGBODY</code></a> whose <em class="replaceable"><code>tagbody-cons</code></em> is indirectly
             accessible.</td><td align="center"><em class="replaceable"><code>k</code></em> := <em class="replaceable"><code>k<sub>1</sub></code></em> + <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a> * <em class="replaceable"><code>k<sub>2</sub></code></em>,
             <em class="replaceable"><code>tagbody-cons</code></em> := *(*(<a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a>+<em class="replaceable"><code>k</code></em>)+<em class="replaceable"><code>n</code></em>).
             If <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDR</code></a>(<em class="replaceable"><code>tagbody-cons</code></em>) = <span class="data"><code class="literal">#&lt;DISABLED&gt;</code></span>, an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a>ed.
             Else <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDR</code></a>(<em class="replaceable"><code>tagbody-cons</code></em>) is a frame-pointer. Unwind the stack up
             to this frame, pass it the number <em class="replaceable"><code>label</code></em>.</td></tr></tbody></table></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="instr-catch"></a>37.5.12. Instructions for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_catch.html" target="_top"><code class="function">CATCH</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_throw.html" target="_top"><code class="function">THROW</code></a></h3></div></div></div><div class="informaltable"><a id="instr-catch-tab"></a><table class="informaltable" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">mnemonic</th><th align="center">description</th><th align="center">semantics</th></tr></thead><tbody><tr><td align="center"><span class="byte"><code class="literal">(CATCH-OPEN <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Create a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_catch.html" target="_top"><code class="function">CATCH</code></a> frame.</td><td align="center">Create a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_catch.html" target="_top"><code class="function">CATCH</code></a> frame, with <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> as tag.
             <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> -= 3, <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> -= 2+<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a>.
             Upon a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_throw.html" target="_top"><code class="function">THROW</code></a> to this tag execution continues at
             <em class="replaceable"><code>label</code></em>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(CATCH-CLOSE)</code></span></td><td align="center">Dissolve a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_catch.html" target="_top"><code class="function">CATCH</code></a> frame.</td><td align="center">Dissolve the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_catch.html" target="_top"><code class="function">CATCH</code></a> frame at <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>.
             <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> += 3, <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> += 2+<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(THROW)</code></span></td><td align="center">Non-local exit to a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_catch.html" target="_top"><code class="function">CATCH</code></a> frame.</td><td align="center"><em class="replaceable"><code>tag</code></em> := *<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>++.
             Search the innermost <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_catch.html" target="_top"><code class="function">CATCH</code></a> frame with tag
             <em class="replaceable"><code>tag</code></em> on the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>, unwind the
             stack up to it, pass it values.</td></tr></tbody></table></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="instr-unwind"></a>37.5.13. Instructions for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_unwind-protect.html" target="_top"><code class="function">UNWIND-PROTECT</code></a></h3></div></div></div><div class="informaltable"><a id="instr-unwind-tab"></a><table class="informaltable" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">mnemonic</th><th align="center">description</th><th align="center">semantics</th></tr></thead><tbody><tr><td align="center"><span class="byte"><code class="literal">(UNWIND-PROTECT-OPEN
             <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center">Create an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_unwind-protect.html" target="_top"><code class="function">UNWIND-PROTECT</code></a> frame.</td><td align="center">Create an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_unwind-protect.html" target="_top"><code class="function">UNWIND-PROTECT</code></a> frame.
             <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> -= 2, <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> -= 2+<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a>.
             When the stack will be unwound by a non-local exit,
             values will be saved on <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>, and execution will be
             transferred to <em class="replaceable"><code>label</code></em>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(UNWIND-PROTECT-NORMAL-EXIT)</code></span></td><td align="center">Dissolve an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_unwind-protect.html" target="_top"><code class="function">UNWIND-PROTECT</code></a> frame, and start the cleanup
             code.</td><td align="center">Dissolve the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_unwind-protect.html" target="_top"><code class="function">UNWIND-PROTECT</code></a> frame at <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>.
             <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> += 2, <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> += 2+<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a>.
             *--<a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> := 0, *--<a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> := 0, *--<a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> := <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>.
             Save the values on the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>,
             <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> -= <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(UNWIND-PROTECT-CLOSE)</code></span></td><td align="center">Terminate the cleanup code.</td><td align="center">newSTACK := *<a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a>++. Load
             values(*(newSTACK-1), ..., *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+0)) into <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">values</code></a>.
             <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := newSTACK. SPword1 := *<a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a>++, SPword2 := *<a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a>++.
             Continue depending on SPword1 and SPword2.
             If both are 0, simply continue execution.
             If SPword2 is 0 but SPword1 is nonzero, interpret it as a
             label and jump to it.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(UNWIND-PROTECT-CLEANUP)</code></span></td><td align="center">Dissolve an <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_unwind-protect.html" target="_top"><code class="function">UNWIND-PROTECT</code></a> frame, and execute the cleanup
             code like a subroutine call.</td><td align="center">Dissolve the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_unwind-protect.html" target="_top"><code class="function">UNWIND-PROTECT</code></a> frame at <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>,
             get <em class="replaceable"><code>label</code></em> out of the frame.
             <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> += 2, <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> += 2+<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">jmpbufsize</code></a>.
             *--<a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> := 0, *--<a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> := PC, *--<a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> := <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>.
             Save the values on the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>, <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> -= <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a>.
             PC := <em class="replaceable"><code>label</code></em>.</td></tr></tbody></table></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="instr-handler"></a>37.5.14. Instructions for <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_handler-bind.html" target="_top"><code class="function">HANDLER-BIND</code></a></h3></div></div></div><div class="informaltable"><a id="instr-handler-tab"></a><table class="informaltable" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">mnemonic</th><th align="center">description</th><th align="center">semantics</th></tr></thead><tbody><tr><td align="center"><span class="byte"><code class="literal">(HANDLER-OPEN <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Create a handler frame.</td><td align="center">Create a handler frame, using <a class="link" href="#comp-fun" title="37.3. The structure of compiled functions"><code class="literal">consts</code></a>[<em class="replaceable"><code>n</code></em>] which
             contains the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_condition.html" target="_top"><code class="classname">CONDITION</code></a> types, the corresponding labels and
             the current <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> depth (= function entry <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> - current <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a>).
             </td></tr><tr><td align="center"><span class="byte"><code class="literal">(HANDLER-BEGIN&amp;PUSH)</code></span></td><td align="center">Start a handler.</td><td align="center">Restore the same <a href="impnotes.html#vm" class="olink"><code class="literal">SP</code></a> state as after the HANDLER-OPEN.
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_condition.html" target="_top"><code class="classname">CONDITION</code></a> that was passed to the handler,
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1.
             *--<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> := <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>.</td></tr></tbody></table></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="instr-inline"></a>37.5.15. Instructions for some inlined
  functions</h3></div></div></div><div class="informaltable"><a id="instr-inline-tab"></a><table class="informaltable" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th align="center">mnemonic</th><th align="center">description</th><th align="center">semantics</th></tr></thead><tbody><tr><td align="center"><span class="byte"><code class="literal">(NOT)</code></span></td><td align="center">Inlined call to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_not.html" target="_top"><code class="function">NOT</code></a>.</td><td align="center"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := not(<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>), <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(EQ)</code></span></td><td align="center">Inlined call to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_eq.html" target="_top"><code class="function">EQ</code></a>.</td><td align="center"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := eq(*<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>++,<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>),
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(CAR)</code></span></td><td align="center">Inlined call to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CAR</code></a>.</td><td align="center"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CAR</code></a>(<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>), <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(CDR)</code></span></td><td align="center">Inlined call to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDR</code></a>.</td><td align="center"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_carcm_cdr_darcm_cddddr.html" target="_top"><code class="function">CDR</code></a>(<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>), <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(CONS)</code></span></td><td align="center">Inlined call to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_cons.html" target="_top"><code class="function">CONS</code></a>.</td><td align="center"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := cons(*<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>++,<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>),
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(SYMBOL-FUNCTION)</code></span></td><td align="center">Inlined call to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_symbol-function.html" target="_top"><code class="function">SYMBOL-FUNCTION</code></a>.</td><td align="center"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_symbol-function.html" target="_top"><code class="function">SYMBOL-FUNCTION</code></a>(<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>),
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(SVREF)</code></span></td><td align="center">Inlined call to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_svref.html" target="_top"><code class="function">SVREF</code></a>.</td><td align="center"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_svref.html" target="_top"><code class="function">SVREF</code></a>(*<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>++,<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>),
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(SVSET)</code></span></td><td align="center">Inlined call to <code class="function">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_setfcm_psetf.html" target="_top"><code class="function">SETF</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_svref.html" target="_top"><code class="function">SVREF</code></a></code>.</td><td align="center"><em class="replaceable"><code>arg1</code></em> := *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+1),
             <em class="replaceable"><code>arg2</code></em> := *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+0), <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> += 2.
             <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_svref.html" target="_top"><code class="function">SVREF</code></a>(<em class="replaceable"><code>arg2</code></em>,<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>) :=
                  <em class="replaceable"><code>arg1</code></em>.
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <em class="replaceable"><code>arg1</code></em>,
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(LIST <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Inlined call to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_listcm_listst.html" target="_top"><code class="function">LIST</code></a>.</td><td align="center"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_listcm_listst.html" target="_top"><code class="function">LIST</code></a>(*(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>-1),...,*(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+0)),
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1, <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> += <em class="replaceable"><code>n</code></em>.</td></tr><tr><td align="center"><span class="byte"><code class="literal">(LIST* <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">Inlined call to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_listcm_listst.html" target="_top"><code class="function">LIST*</code></a>.</td><td align="center"><a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a> := <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_listcm_listst.html" target="_top"><code class="function">LIST*</code></a>(*(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+<em class="replaceable"><code>n</code></em>-1),...,
                                     *(<a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>+0),<a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">value1</code></a>),
             <a class="link" href="#vm" title="37.2. The virtual machine"><code class="varname">mv_count</code></a> := 1, <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> += <em class="replaceable"><code>n</code></em>.</td></tr></tbody></table></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="instr-combo"></a>37.5.16. Combined instructions</h3></div></div></div><p>The most frequent short sequences of instructions have an
equivalent combined instruction.  They are only present for space and
speed optimization. The only exception is
<span class="byte"><code class="literal">FUNCALL&amp;SKIP&amp;RETGF</code></span>, which is needed for
generic functions.</p><div class="informaltable"><a id="instr-combo-tab"></a><table class="informaltable" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="center">mnemonic</th><th align="center">equivalent</th></tr></thead><tbody><tr><td align="center"><span class="byte"><code class="literal">(NIL&amp;PUSH)</code></span></td><td align="center"><span class="byte"><code class="literal">(NIL) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(T&amp;PUSH)</code></span></td><td align="center"><span class="byte"><code class="literal">(T) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CONST&amp;PUSH <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CONST <em class="replaceable"><code>n</code></em>) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOAD&amp;PUSH <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(LOAD <em class="replaceable"><code>n</code></em>) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOADI&amp;PUSH <em class="replaceable"><code>k<sub>1</sub></code></em> <em class="replaceable"><code>k<sub>2</sub></code></em> <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(LOADI <em class="replaceable"><code>k<sub>1</sub></code></em> <em class="replaceable"><code>k<sub>2</sub></code></em> <em class="replaceable"><code>n</code></em>) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOADC&amp;PUSH <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>m</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(LOADC <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>m</code></em>) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOADV&amp;PUSH <em class="replaceable"><code>k</code></em> <em class="replaceable"><code>m</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(LOADV <em class="replaceable"><code>k</code></em> <em class="replaceable"><code>m</code></em>) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(POP&amp;STORE <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(POP) (STORE <em class="replaceable"><code>n</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(GETVALUE&amp;PUSH <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(GETVALUE <em class="replaceable"><code>n</code></em>) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(JSR&amp;PUSH <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(JSR <em class="replaceable"><code>label</code></em>) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(COPY-CLOSURE&amp;PUSH <em class="replaceable"><code>m</code></em> <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(COPY-CLOSURE <em class="replaceable"><code>m</code></em> <em class="replaceable"><code>n</code></em>) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALL&amp;PUSH <em class="replaceable"><code>k</code></em> <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALL <em class="replaceable"><code>k</code></em> <em class="replaceable"><code>n</code></em>) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALL1&amp;PUSH <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALL1 <em class="replaceable"><code>n</code></em>) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALL2&amp;PUSH <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALL2 <em class="replaceable"><code>n</code></em>) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALLS1&amp;PUSH <em class="replaceable"><code>b</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALLS1 <em class="replaceable"><code>b</code></em>) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALLS2&amp;PUSH <em class="replaceable"><code>b</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALLS2 <em class="replaceable"><code>b</code></em>) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALLSR&amp;PUSH <em class="replaceable"><code>m</code></em> <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALLSR <em class="replaceable"><code>m</code></em> <em class="replaceable"><code>n</code></em>) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALLC&amp;PUSH)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALLC) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALLCKEY&amp;PUSH)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALLCKEY) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(FUNCALL&amp;PUSH <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(FUNCALL <em class="replaceable"><code>n</code></em>) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(APPLY&amp;PUSH <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(APPLY <em class="replaceable"><code>n</code></em>) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CAR&amp;PUSH)</code></span></td><td align="center"><span class="byte"><code class="literal">(CAR) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CDR&amp;PUSH)</code></span></td><td align="center"><span class="byte"><code class="literal">(CDR) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CONS&amp;PUSH)</code></span></td><td align="center"><span class="byte"><code class="literal">(CONS) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(LIST&amp;PUSH <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(LIST <em class="replaceable"><code>n</code></em>) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(LIST*&amp;PUSH <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(LIST* <em class="replaceable"><code>n</code></em>) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(NIL&amp;STORE <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(NIL) (STORE <em class="replaceable"><code>n</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(T&amp;STORE <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(T) (STORE <em class="replaceable"><code>n</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOAD&amp;STOREC <em class="replaceable"><code>k</code></em> <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>m</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(LOAD <em class="replaceable"><code>k</code></em>) (STOREC <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>m</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALLS1&amp;STORE <em class="replaceable"><code>b</code></em> <em class="replaceable"><code>k</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALLS1 <em class="replaceable"><code>b</code></em>) (STORE <em class="replaceable"><code>k</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALLS2&amp;STORE <em class="replaceable"><code>b</code></em> <em class="replaceable"><code>k</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALLS2 <em class="replaceable"><code>b</code></em>) (STORE <em class="replaceable"><code>k</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALLSR&amp;STORE <em class="replaceable"><code>m</code></em> <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>k</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALLSR <em class="replaceable"><code>m</code></em> <em class="replaceable"><code>n</code></em>) (STORE <em class="replaceable"><code>k</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOAD&amp;CDR&amp;STORE <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(LOAD <em class="replaceable"><code>n</code></em>) (CDR) (STORE <em class="replaceable"><code>n</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOAD&amp;CONS&amp;STORE <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(LOAD <em class="replaceable"><code>n</code></em>+1) (CONS) (STORE <em class="replaceable"><code>n</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOAD&amp;INC&amp;STORE <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(LOAD <em class="replaceable"><code>n</code></em>) (CALL1 #'1+) (STORE <em class="replaceable"><code>n</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOAD&amp;DEC&amp;STORE <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(LOAD <em class="replaceable"><code>n</code></em>) (CALL1 #'1-) (STORE <em class="replaceable"><code>n</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOAD&amp;CAR&amp;STORE <em class="replaceable"><code>m</code></em> <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(LOAD <em class="replaceable"><code>m</code></em>) (CAR) (STORE <em class="replaceable"><code>n</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALL1&amp;JMPIF <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALL1 <em class="replaceable"><code>n</code></em>) (JMPIF <em class="replaceable"><code>label</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALL1&amp;JMPIFNOT <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALL1 <em class="replaceable"><code>n</code></em>) (JMPIFNOT <em class="replaceable"><code>label</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALL2&amp;JMPIF <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALL2 <em class="replaceable"><code>n</code></em>) (JMPIF <em class="replaceable"><code>label</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALL2&amp;JMPIFNOT <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALL2 <em class="replaceable"><code>n</code></em>) (JMPIFNOT <em class="replaceable"><code>label</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALLS1&amp;JMPIF <em class="replaceable"><code>b</code></em> <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALLS1 <em class="replaceable"><code>b</code></em>) (JMPIF <em class="replaceable"><code>label</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALLS1&amp;JMPIFNOT <em class="replaceable"><code>b</code></em> <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALLS1 <em class="replaceable"><code>b</code></em>) (JMPIFNOT <em class="replaceable"><code>label</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALLS2&amp;JMPIF <em class="replaceable"><code>b</code></em> <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALLS2 <em class="replaceable"><code>b</code></em>) (JMPIF <em class="replaceable"><code>label</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALLS2&amp;JMPIFNOT <em class="replaceable"><code>b</code></em> <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALLS2 <em class="replaceable"><code>b</code></em>) (JMPIFNOT <em class="replaceable"><code>label</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALLSR&amp;JMPIF <em class="replaceable"><code>m</code></em> <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALLSR <em class="replaceable"><code>m</code></em> <em class="replaceable"><code>n</code></em>) (JMPIF <em class="replaceable"><code>label</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CALLSR&amp;JMPIFNOT <em class="replaceable"><code>m</code></em> <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CALLSR <em class="replaceable"><code>m</code></em> <em class="replaceable"><code>n</code></em>) (JMPIFNOT <em class="replaceable"><code>label</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOAD&amp;JMPIF <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(LOAD <em class="replaceable"><code>n</code></em>) (JMPIF <em class="replaceable"><code>label</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOAD&amp;JMPIFNOT <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>label</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(LOAD <em class="replaceable"><code>n</code></em>) (JMPIFNOT <em class="replaceable"><code>label</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOAD&amp;CAR&amp;PUSH <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(LOAD <em class="replaceable"><code>n</code></em>) (CAR) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOAD&amp;CDR&amp;PUSH <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(LOAD <em class="replaceable"><code>n</code></em>) (CDR) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOAD&amp;INC&amp;PUSH <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(LOAD <em class="replaceable"><code>n</code></em>) (CALL1 #'1+) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOAD&amp;DEC&amp;PUSH <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(LOAD <em class="replaceable"><code>n</code></em>) (CALL1 #'1-) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CONST&amp;SYMBOL-FUNCTION <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CONST <em class="replaceable"><code>n</code></em>) (SYMBOL-FUNCTION)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CONST&amp;SYMBOL-FUNCTION&amp;PUSH <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CONST <em class="replaceable"><code>n</code></em>) (SYMBOL-FUNCTION) (PUSH)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(CONST&amp;SYMBOL-FUNCTION&amp;STORE <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>k</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(CONST <em class="replaceable"><code>n</code></em>) (SYMBOL-FUNCTION) (STORE <em class="replaceable"><code>k</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(APPLY&amp;SKIP&amp;RET <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>k</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(APPLY <em class="replaceable"><code>n</code></em>) (SKIP&amp;RET <em class="replaceable"><code>k</code></em>)</code></span></td></tr><tr><td align="center"><span class="byte"><code class="literal">(FUNCALL&amp;SKIP&amp;RETGF <em class="replaceable"><code>n</code></em> <em class="replaceable"><code>k</code></em>)</code></span></td><td align="center"><span class="byte"><code class="literal">(FUNCALL <em class="replaceable"><code>n</code></em>) (SKIP&amp;RETGF <em class="replaceable"><code>k</code></em>)</code></span></td></tr></tbody></table></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="instr-shortcut"></a>37.5.17. Shortcut instructions</h3></div></div></div><p>There are special one-byte instructions (without explicit
operands) for the following frequent instructions:</p><div class="informaltable"><a id="instr-shortcut-tab"></a><table class="informaltable" border="1"><colgroup><col /><col /></colgroup><thead><tr><th align="center">mnemonic</th><th align="center">operand range</th></tr></thead><tbody><tr><td align="center"><span class="byte"><code class="literal">(LOAD <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">0 ≤ <em class="replaceable"><code>n</code></em> &lt; 15</td></tr><tr><td align="center"><span class="byte"><code class="literal">(LOAD&amp;PUSH <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">0 ≤ <em class="replaceable"><code>n</code></em> &lt; 25</td></tr><tr><td align="center"><span class="byte"><code class="literal">(CONST <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">0 ≤ <em class="replaceable"><code>n</code></em> &lt; 21</td></tr><tr><td align="center"><span class="byte"><code class="literal">(CONST&amp;PUSH <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">0 ≤ <em class="replaceable"><code>n</code></em> &lt; 30</td></tr><tr><td align="center"><span class="byte"><code class="literal">(STORE <em class="replaceable"><code>n</code></em>)</code></span></td><td align="center">0 ≤ <em class="replaceable"><code>n</code></em> &lt; 8</td></tr></tbody></table></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="compiler-introspection"></a>37.6. Examining compiled closures</h2></div></div></div><p>The functions described here are defined
 in <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/compiler.lisp"><code class="filename">src/compiler.lisp</code></a>
 and <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/record.d"><code class="filename">src/record.d</code></a>
 and can be used to examine the internals of a compiled closure.</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p>These function are <span class="emphasis"><em>internal</em></span> <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
  functions, their names are <span class="strong"><strong>not</strong></span> exported, this section is
  <span class="strong"><strong>not</strong></span> supposed to be comprehensive and is <span class="strong"><strong>not</strong></span> guaranteed to be
  up to date.  It is intended for aspiring <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> hackers who are
  supposed to graduate to reading the sources right away. All others
  should stick with the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] function <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_disassemble.html" target="_top"><code class="function">DISASSEMBLE</code></a>.</p></div><p><a id="closure-name"></a><strong>Closure name. </strong>The normal way to extract the name of a closure is
 <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_function-_a-expression.html" target="_top"><code class="function">FUNCTION-LAMBDA-EXPRESSION</code></a>:
</p><pre class="programlisting">
(defun my-plus-1 (x y) (declare (compile)) (+ x y))
⇒ <code class="computeroutput">MY-PLUS-1</code>
(function-lambda-expression #'my-plus-1)
⇒ <code class="computeroutput">(LAMBDA (X Y) (DECLARE (COMPILE)) (+ X Y))</code> ;
⇒ <code class="computeroutput"><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a></code> ;
⇒ <code class="computeroutput">MY-PLUS-1</code>
;; works only on closure objects
(sys::closure-name #'my-plus-1)
⇒ <code class="computeroutput">MY-PLUS-1</code></pre><p><a id="closure-codevec"></a><strong>Closure bytecode. </strong>The actual bytecode vector (if you modify it, you can get a
 segfault when the function is executed):</p><pre class="programlisting">
(sys::closure-codevec #'my-plus-1)
⇒ <code class="computeroutput">#(0 0 0 0 2 0 0 0 6 3 174 174 51 2 53 25 3)</code></pre><p><a id="closure-consts"></a><strong>Closure constants. </strong>A closure can depend on external and internal values:
 </p><pre class="programlisting">
(let ((x 123) (y 456))
  (defun my-plus-2 (z) (declare (compile)) (+ x y z)))
⇒ <code class="computeroutput">MY-PLUS-2</code>
(sys::closure-consts #'my-plus-2)
⇒ <code class="computeroutput">(#(Y 456 X 123 NIL) 3 1)</code></pre><p>
Use <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_disassemble.html" target="_top"><code class="function">DISASSEMBLE</code></a> to see how the constants are used.</p><p><a id="signature"></a><strong>Closure signature. </strong>Function <code class="function">SYS::SIGNATURE</code> returns 8 values:
</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">required parameter count</li><li class="listitem">optional parameters count</li><li class="listitem">rest-p</li><li class="listitem">key-p</li><li class="listitem">keyword-p</li><li class="listitem">allow-other-keys-p</li><li class="listitem">byte-list (codevec as a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>)</li><li class="listitem">const-list</li></ol></div><p><a id="closure-LAP"></a><strong>Mnemonic bytecodes. </strong>One can convert between numeric and mnemonic bytecodes
 (<span class="quote">“<span class="quote">LAP</span>”</span> stands for <span class="quote">“<span class="quote">Lisp Assembly Program</span>”</span>):
</p><pre class="programlisting">
(multiple-value-bind (req-num opt-num rest-p key-p keyword-list
                      allow-other-keys-p byte-list const-list)
    (sys::signature #'my-plus-1)
  (sys::disassemble-LAP byte-list const-list))
⇒ <code class="computeroutput">((0 LOAD&amp;PUSH 2) (1 LOAD&amp;PUSH 2) (2 CALLSR 2 53) (5 SKIP&amp;RET 3))</code>
(sys::assemble-LAP (mapcar #'rest *))
⇒ <code class="computeroutput">(174 174 51 2 53 25 3)</code></pre><p>
</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="bytecode-design"></a>37.7. Bytecode Design</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#byte-when-add-q">37.7.1. When to add a new bytecode?</a></span></dt><dt><span class="section"><a href="#byte-jmptail-q">37.7.2. Why JMPTAIL?</a></span></dt></dl></div><p>This section offers some insight into bytecode design in the form
 of questions and answers.</p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="byte-when-add-q"></a>37.7.1. When to add a new bytecode?</h3></div></div></div><div class="abstract"><p class="title"><strong>Question:</strong></p><p>Does it make sense to define a new bytecode instruction for
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_restart-case.html" target="_top"><code class="function">RESTART-CASE</code></a>? Why? Why not?</p></div><div class="simplesect"><div class="titlepage"><div><div><h4 class="title"><a id="byte-when-add-a"></a>Answer: Is it speed critical?</h4></div></div></div><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_restart-case.html" target="_top"><code class="function">RESTART-CASE</code></a> is a glorified <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/speope_letcm_letst.html" target="_top"><code class="function">LET</code></a> binding
   for <code class="varname">SYSTEM::*ACTIVE-RESTARTS*</code> and could well profit
   from a separate bytecode: it would make it non-<a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#cons">cons</a>ing[3].
   (Remember that <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_restart.html" target="_top"><code class="classname">RESTART</code></a>s have dynamic extent and therefore do not
   really need to be heap allocated.)</p><p>The reason <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_handler-bind.html" target="_top"><code class="function">HANDLER-BIND</code></a> has its own bytecodes and
   <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_restart-case.html" target="_top"><code class="function">RESTART-CASE</code></a> does not is that <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_handler-bind.html" target="_top"><code class="function">HANDLER-BIND</code></a> can occur in inner
   computation loops, whereas <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_restart-case.html" target="_top"><code class="function">RESTART-CASE</code></a> occurs only as part of
   user-interface programming and therefore not in inner loops where its
   consing could hurt much.</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="byte-jmptail-q"></a>37.7.2. Why <a class="link" href="#instr-jump" title="37.5.5. Instructions for control flow, jumps">JMPTAIL</a>?</h3></div></div></div><div class="abstract"><p class="title"><strong>Question:</strong></p><p>Consider this function and its disassembly:
</p><pre class="programlisting">
(defun foo (x y) (if (or (= x 0) (= y 0)) (+ x y) (foo y (1- x))))
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_disassemble.html" target="_top"><code class="function">DISASSEMBLE</code></a> 'foo)
8     (LOAD&amp;PUSH 1)
9     (LOAD&amp;DEC&amp;PUSH 3)
11    (JMPTAIL 2 5 L0)</pre><p>
    Why are the arguments pushed onto the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a>, just to be popped off of
    it during the <span class="byte"><code class="literal">JMPTAIL</code></span>?
    Why not a sequence of <span class="byte"><code class="literal">LOAD</code></span>,
    <span class="byte"><code class="literal">STORE</code></span> and
    <span class="byte"><code class="literal">SKIP</code></span> instructions
    followed by a <span class="byte"><code class="literal">JMP</code></span>?
 </p></div><div class="simplesect"><div class="titlepage"><div><div><h4 class="title"><a id="byte-jmptail-a"></a>Answer: This is a shortcut for the most common use</h4></div></div></div><p>Using <span class="byte"><code class="literal">JMPTAIL</code></span> requires 3
   instructions, <span class="byte"><code class="literal">JMP</code></span> requires more.
   When <span class="byte"><code class="literal">JMPTAIL</code></span> needs to be called, we
   usually have some stuff close to the top of the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> which will
   become the new arguments, and some junk between these new arguments
   and the closure object.  <span class="byte"><code class="literal">JMPTAIL</code></span>
   removes the junk.  <span class="byte"><code class="literal">JMPTAIL</code></span> is a
   convenient shortcut which shortens the bytecode - because typically
   one would really have to clean-up the <a href="impnotes.html#vm" class="olink"><code class="literal">STACK</code></a> by hand or make the
   calculations in <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/compiler.lisp"><code class="filename">src/compiler.lisp</code></a>
   more complicated.</p></div></div></div></div></div><div class="part"><div class="titlepage"><div><div><h1 class="title"><a id="appendices"></a>Part V. Appendices</h1></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="appendix"><a href="#faq">A. Frequently Asked Questions (With Answers)   about <span class="command"><strong>CLISP</strong></span></a></span></dt><dt><span class="appendix"><a href="#fdl">B. GNU Free Documentation License</a></span></dt><dt><span class="appendix"><a href="#gpl">C. GNU General Public License</a></span></dt><dd><dl><dt><span class="section"><a href="#gpl-1">C.1. Preamble</a></span></dt><dt><span class="section"><a href="#gpl-2">C.2. TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION</a></span></dt><dd><dl><dt><span class="section"><a href="#gpl-2-0">C.2.1. Section 0</a></span></dt><dt><span class="section"><a href="#gpl-2-1">C.2.2. Section 1</a></span></dt><dt><span class="section"><a href="#gpl-2-2">C.2.3. Section 2</a></span></dt><dt><span class="section"><a href="#gpl-2-3">C.2.4. Section 3</a></span></dt><dt><span class="section"><a href="#gpl-2-4">C.2.5. Section 4</a></span></dt><dt><span class="section"><a href="#gpl-2-5">C.2.6. Section 5</a></span></dt><dt><span class="section"><a href="#gpl-2-6">C.2.7. Section 6</a></span></dt><dt><span class="section"><a href="#gpl-2-7">C.2.8. Section 7</a></span></dt><dt><span class="section"><a href="#gpl-2-8">C.2.9. Section 8</a></span></dt><dt><span class="section"><a href="#gpl-2-9">C.2.10. Section 9</a></span></dt><dt><span class="section"><a href="#gpl-2-10">C.2.11. Section 10</a></span></dt><dt><span class="section"><a href="#gpl-2-11">C.2.12. NO WARRANTY Section 11</a></span></dt><dt><span class="section"><a href="#gpl-2-12">C.2.13. Section 12</a></span></dt></dl></dd><dt><span class="section"><a href="#gpl-3">C.3. How to Apply These Terms to Your New Programs</a></span></dt></dl></dd></dl></div><div class="appendix"><div class="titlepage"><div><div><h2 class="title"><a id="faq"></a>Appendix A. Frequently Asked Questions (With Answers)
  about <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a></h2></div></div></div><div class="abstract"><a id="faq-abstract"></a><p class="title"><strong>Abstract</strong></p><p>This is a list of frequently asked questions about <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> on the
<a class="link" href="#faq-mailing-lists" title="A.1.1.6.">CLISP mailing lists</a>
and the USENET newsgroup <a class="" href="https://groups.google.com/group/comp.lang.lisp">comp.lang.lisp</a>.
<span class="emphasis"><em>All</em></span> the legitimate technical question are addressed
in the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> documentation (<a href="impnotes.html#impnotes-top" class="olink"><span class="command"><strong>CLISP</strong></span> impnotes</a>,
<a href="clisp.html#clisp" class="olink"><span class="refentrytitle">clisp</span>(1)</a>, <a href="clisp-link.html#clisp-link" class="olink"><span class="refentrytitle">clisp-link</span>(1)</a>), and for such
questions this list provides a link into the docs.
The frequently asked <a class="link" href="#faq-meta" title="Meta Information">political</a> questions
are answered here in <span class="emphasis"><em>full</em></span> detail (meaning that no
further explanations of the issues could be provided).</p><p>Please submit more questions (and answers!)
 to <a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-list/">clisp-list</a>.</p></div><div class="qandaset"><h2 class="title"><a id="faq-set"></a>FAQ</h2><dl><dt>A.1.  <a href="#faq-meta">Meta Information</a></dt><dd><dl><dt>A.1.1.  <a href="#faq-meta-misc">Miscellaneous</a></dt><dd><dl><dt>A.1.1.1. <a href="#faq-fine">What is
   “FAQ fine”?</a></dt><dt>A.1.1.2. <a href="#faq-doc">The official CLISP
   documentation sucks - is anything better available?</a></dt><dt>A.1.1.3. <a href="#faq-gpl">License
   - why GNU GPL?</a></dt><dt>A.1.1.4. <a href="#faq-ansi">What about
   [ANSI CL standard] compliance?</a></dt><dt>A.1.1.5. <a href="#faq-help">How do I
   ask for help?</a></dt><dt>A.1.1.6. <a href="#faq-mailing-lists">Which mailing lists should I subscribe to?</a></dt><dt>A.1.1.7. <a href="#faq-rejected">Why
   is my mail to a mailing list rejected?</a></dt><dt>A.1.1.8. <a href="#faq-bugs">How do I
   report bugs?</a></dt><dt>A.1.1.9. <a href="#faq-contrib">How
   do I help?</a></dt><dt>A.1.1.10. <a href="#faq-debug">How do I
   debug CLISP?</a></dt></dl></dd><dt>A.1.2.  <a href="#faq-menorah">Logo</a></dt><dd><dl><dt>A.1.2.1. <a href="#faq-menorah-why">Why
   is CLISP using menorah as the logo?</a></dt><dt>A.1.2.2. <a href="#faq-menorah-current">Shouldn't the logo be changed now due to the current
   political developments in the Middle East?</a></dt><dt>A.1.2.3. <a href="#faq-menorah-other">Aren't there other political issues of concern?</a></dt><dt>A.1.2.4. <a href="#faq-menorah-users">Aren't you afraid of losing some users who are offended by
   the logo?</a></dt><dt>A.1.2.5. <a href="#faq-menorah-unprofessional">Using software to
   promote a political agenda is unprofessional!</a></dt></dl></dd></dl></dd><dt>A.2.  <a href="#faq-run">Running <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a></a></dt><dd><dl><dt>A.2.1. <a href="#faq-defun">Why are floats printed in binary?</a></dt><dt>A.2.2. <a href="#faq-ide">Where is the IDE?</a></dt><dt>A.2.3. <a href="#faq-opt">What are the
   command line arguments?</a></dt><dt>A.2.4. <a href="#faq-debugger">How
   do I get out of the debugger?</a></dt><dt>A.2.5. <a href="#faq-ext">What CLISP
   extensions are available?</a></dt><dt>A.2.6. <a href="#faq-rc">Where is the
   init (“RC”) file on my platform?</a></dt><dt>A.2.7. <a href="#faq-modules">Where
   are the modules with which I built CLISP?</a></dt><dt>A.2.8. <a href="#faq-gui">How do I create
   a GUI
   for my CLISP program?</a></dt></dl></dd><dt>A.3.  <a href="#faq-delivery">Application Delivery</a></dt><dd><dl><dt>A.3.1. <a href="#faq-exec">How do I
   create an executable file with all my code in it?</a></dt><dt>A.3.2. <a href="#faq-licensing">When
   I deliver my application with CLISP, does it have to be covered by
   the GNU GPL?</a></dt></dl></dd><dt>A.4.  <a href="#faq-trouble">Troubles</a></dt><dd><dl><dt>A.4.1. <a href="#faq-bin-distrib">Where
   is the binary distribution for my platform?</a></dt><dt>A.4.2. <a href="#faq-bin-distrib-prev">But a previous release had a binary
   distribution for my platform, why does not the current one?</a></dt><dt>A.4.3. <a href="#faq-build">Why does not
   CLISP build on my platform?</a></dt><dt>A.4.4. <a href="#faq-with-prefix">
   Why is the --with-libsigsegv-prefix option ignored
   by the configure script on my 64-bit machine?</a></dt><dt>A.4.5. <a href="#faq-enc-err">What do charset errors mean?</a></dt><dt>A.4.6. <a href="#faq-rl-tab">What does
   this message mean: “Display all 1259
     possibilities? (y or n)”</a></dt><dt>A.4.7. <a href="#faq-no-rl">Why does
   not command line editing work?</a></dt><dt>A.4.8. <a href="#faq-stack">How do I
   avoid stack overflow?</a></dt><dt>A.4.9. <a href="#faq-self-mod">Why does my function return different values on each
   invocation and then hangs forever?</a></dt><dt>A.4.10. <a href="#faq-fp">Is floating point arithmetic broken?</a></dt><dt>A.4.11. <a href="#faq-random">Is RANDOM broken?</a></dt><dt>A.4.12. <a href="#faq-pp-newline">Why is an extra line break
   inserted by the pretty printer?</a></dt><dt>A.4.13. <a href="#faq-warning">How do I disable this annoying
   warning?</a></dt><dt>A.4.14. <a href="#faq-scope">Why does DEFVAR affect previously defined lexical closures?</a></dt><dt>A.4.15. <a href="#faq-bad-error">The error message is not helpful!</a></dt><dt>A.4.16. <a href="#faq-other-problem">Why is the function FOO
   broken?!</a></dt></dl></dd></dl><table border="0" style="width: 100%;"><colgroup><col align="left" width="1%" /><col /></colgroup><tbody><tr class="qandadiv"><td align="left" valign="top" colspan="2"><h3 class="title"><a id="faq-meta"></a>A.1. Meta Information</h3></td></tr><tr class="toc"><td align="left" valign="top" colspan="2"><dl><dt>A.1.1.  <a href="#faq-meta-misc">Miscellaneous</a></dt><dd><dl><dt>A.1.1.1. <a href="#faq-fine">What is
   “FAQ fine”?</a></dt><dt>A.1.1.2. <a href="#faq-doc">The official CLISP
   documentation sucks - is anything better available?</a></dt><dt>A.1.1.3. <a href="#faq-gpl">License
   - why GNU GPL?</a></dt><dt>A.1.1.4. <a href="#faq-ansi">What about
   [ANSI CL standard] compliance?</a></dt><dt>A.1.1.5. <a href="#faq-help">How do I
   ask for help?</a></dt><dt>A.1.1.6. <a href="#faq-mailing-lists">Which mailing lists should I subscribe to?</a></dt><dt>A.1.1.7. <a href="#faq-rejected">Why
   is my mail to a mailing list rejected?</a></dt><dt>A.1.1.8. <a href="#faq-bugs">How do I
   report bugs?</a></dt><dt>A.1.1.9. <a href="#faq-contrib">How
   do I help?</a></dt><dt>A.1.1.10. <a href="#faq-debug">How do I
   debug CLISP?</a></dt></dl></dd><dt>A.1.2.  <a href="#faq-menorah">Logo</a></dt><dd><dl><dt>A.1.2.1. <a href="#faq-menorah-why">Why
   is CLISP using menorah as the logo?</a></dt><dt>A.1.2.2. <a href="#faq-menorah-current">Shouldn't the logo be changed now due to the current
   political developments in the Middle East?</a></dt><dt>A.1.2.3. <a href="#faq-menorah-other">Aren't there other political issues of concern?</a></dt><dt>A.1.2.4. <a href="#faq-menorah-users">Aren't you afraid of losing some users who are offended by
   the logo?</a></dt><dt>A.1.2.5. <a href="#faq-menorah-unprofessional">Using software to
   promote a political agenda is unprofessional!</a></dt></dl></dd></dl></td></tr><tr class="qandadiv"><td align="left" valign="top" colspan="2"><h4 class="title"><a id="faq-meta-misc"></a>A.1.1. Miscellaneous</h4></td></tr><tr class="toc"><td align="left" valign="top" colspan="2"><dl><dt>A.1.1.1. <a href="#faq-fine">What is
   “FAQ fine”?</a></dt><dt>A.1.1.2. <a href="#faq-doc">The official CLISP
   documentation sucks - is anything better available?</a></dt><dt>A.1.1.3. <a href="#faq-gpl">License
   - why GNU GPL?</a></dt><dt>A.1.1.4. <a href="#faq-ansi">What about
   [ANSI CL standard] compliance?</a></dt><dt>A.1.1.5. <a href="#faq-help">How do I
   ask for help?</a></dt><dt>A.1.1.6. <a href="#faq-mailing-lists">Which mailing lists should I subscribe to?</a></dt><dt>A.1.1.7. <a href="#faq-rejected">Why
   is my mail to a mailing list rejected?</a></dt><dt>A.1.1.8. <a href="#faq-bugs">How do I
   report bugs?</a></dt><dt>A.1.1.9. <a href="#faq-contrib">How
   do I help?</a></dt><dt>A.1.1.10. <a href="#faq-debug">How do I
   debug CLISP?</a></dt></dl></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-fine"></a><a id="faq-fine-q"></a><p><strong>A.1.1.1.</strong></p></td><td align="left" valign="top"><p>What is
   <span class="quote">“<span class="quote">FAQ fine</span>”</span>?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>We levy a fine of 10 zorkmids for
   <a class="link" href="#faq-help" title="A.1.1.5.">asking a question</a> that is answered
   with a link to this <a class="link" href="#faq" title="Appendix A. Frequently Asked Questions (With Answers) about CLISP">FAQ</a> document.
   We further levy a fine of 1 zorkmid for asking a question that is answered
   with a link to the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a class="link" href="#impnotes-top" title="Implementation Notes for GNU CLISP">manual</a>.
   The fines are payable to the person who answered the questions.
   The definition of a <span class="quote">“<span class="quote">zorkmid</span>”</span> is left to the sole
   discretion of the <span class="emphasis"><em>payer</em></span>.</p><p>This should <span class="strong"><strong>not</strong></span> discourage you from asking questions, but
   rather <span class="strong"><strong>encourage</strong></span> you to
   <span class="strong"><strong>read</strong></span> the manual and
   <span class="strong"><strong>answer</strong></span> questions from other users.</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-doc"></a><a id="faq-doc-q"></a><p><strong>A.1.1.2.</strong></p></td><td align="left" valign="top"><p>The official <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
   documentation sucks - is anything better available?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>As with all generic complaints, the answer to this one is
   <a class="ulink" href="http://www.cygwin.com/acronyms/#PTC" target="_top"><acronym class="acronym" title="Patches Thoughtfully Considered">PTC</acronym></a>.</p><p>Additionally, the nightly builds of the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> implementation
   notes documenting the current <a class="ulink" href="https://www.mercurial-scm.org/" target="_top">Mercurial</a> <code class="literal">default</code> branch
   are available at <a class="ulink" href="http://clisp.org/beta/impnotes/" target="_top">http://clisp.org/beta/impnotes/</a>.
   It contains both the documentation for the new features and the
   general improvements in the documentation.</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-gpl"></a><a id="faq-gpl-q"></a><p><strong>A.1.1.3.</strong></p></td><td align="left" valign="top"><p>License
   - why <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/copyleft/gpl.html" target="_top">GPL</a>?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p><a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/doc/Why-CLISP-is-under-GPL">Because
   <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> uses <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://tiswww.case.edu/php/chet/readline/readline.html" target="_top">readline</a></a>.</p><p>Note that this does <span class="strong"><strong>not</strong></span> necessarily prevent you from distributing
 your proprietary products based on <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>. See <span class="emphasis"><em>Note</em></span>
 in <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/COPYRIGHT"><code class="filename">COPYRIGHT</code></a> and
 <a class="xref" href="#faq-licensing" title="A.3.2.">Q: A.3.2</a>.</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-ansi"></a><a id="faq-ansi-q"></a><p><strong>A.1.1.4.</strong></p></td><td align="left" valign="top"><p>What about
   [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] compliance?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_p.html#purports_to_conform"><span class="emphasis"><em>purports to
    conform</em></span></a> to the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] specification, so all
  deviations in </p><pre class="screen"><strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp.html#clisp" class="olink">clisp</a></strong></span> <code class="option"><a href="clisp.html#opt-ansi" class="olink">-ansi</a></code></pre><p>
  from the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] are bugs and are not (yet) fixed only due
  to lack of resources.</p><p>On the other hand, some decisions made by the ANSI X3J13 committee
  were not as justified from the <span class="emphasis"><em>technical</em></span> point of
  view as were most of them, and some of those questionable decisions
  were made <span class="strong"><strong>after</strong></span> the alternative behavior has already been implemented
  in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.  The <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> developers took pains to modify <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> to
  unconditionally comply with the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>] specification in all cases
  <a class="link" href="#ansi" title="31.10. Maximum ANSI CL compliance">except for a handful of situations where they
  believed that the committee had made a mistake</a>, in which cases
  the committee behavior is <span class="emphasis"><em>still</em></span> optionally
  available.</p><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> does not start in the ansi mode by default for
  historical reasons and this is not about to change.
  <a class="link" href="#image" title="31.2. Saving an Image">Dumping an image</a> or
  <a href="clisp.html#opt-ansi" class="olink">passing a command line
   argument</a> are easy enough.</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-help"></a><a id="faq-help-q"></a><p><strong>A.1.1.5.</strong></p></td><td align="left" valign="top"><p>How do I
   ask for help?</p></td></tr><tr class="answer"><td align="left" valign="top"><p><strong><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a></strong></p></td><td align="left" valign="top"><p>Type <a href="impnotes.html#debugger-main-deb-step" class="olink"><span class="command"><strong>help</strong></span></a> and hit <span class="keycap"><strong>Enter</strong></span>.</p></td></tr><tr class="answer"><td align="left" valign="top"><p><strong>Human</strong></p></td><td align="left" valign="top"><p>Politely - please refer to <a class="rfc" href="http://www.ietf.org/rfc/rfc1855.txt"><code>Netiquette</code></a>.</p><p>If you have a question about <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>, you have the following options
  (listed in the order of decreasing audience size):</p><div class="variablelist"><dl class="variablelist"><dt><span class="term">the USENET newsgroup <a class="" href="https://groups.google.com/group/comp.lang.lisp">comp.lang.lisp</a></span></dt><dd>This is the right place to ask all general Lisp
      questions, such as <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/acc_charcm_schar.html">"how
       do I access a character in a string?"</a></dd><dt><span class="term"><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> User Mailing
     List <a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-list/">clisp-list</a></span></dt><dd><p class="simpara">This is the right place to ask user-level
      <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>-specific questions, such as <span class="quote">“<span class="quote">"how do I save my <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
      <a href="impnotes.html#image" class="olink">memory image</a>?"</span>”</span>.</p><p class="simpara">See also <a class="xref" href="#faq-bugs" title="A.1.1.8.">Q: A.1.1.8</a>.</p></dd><dt><span class="term"><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> Developer Mailing
     List <a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-devel/">clisp-devel</a></span></dt><dd>This is the right place to discuss <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> internals,
      problems with the current development sources, submit patches,
      offer help.</dd><dt><span class="term"><a class="ulink" href="https://sourceforge.net/p/clisp/_members/" target="_top">Individual <span class="command"><strong>CLISP</strong></span> developers</a></span></dt><dd><p class="simpara">This is <span class="emphasis"><em>never</em></span> the right thing to
      do, unless you want to <span class="emphasis"><em>hire</em></span> this developer to do
      <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> consulting (commercial support, custom enhancements etc).
      This is actually for your own benefit: the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> developers are very
      busy, they might get weeks to answer your question,
      and some other user may be able to help you in the meantine;
      as well as for the benefit of the other <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> users,
      since the mailing lists are publicly archived (you are encouraged
      to <a class="ulink" href="http://clisp.org/#search" target="_top">search</a> them
      before asking).</p><p class="simpara">Please do <span class="strong"><strong>not</strong></span> copy your messages to the individual
      developers.</p></dd></dl></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Mailing lists are member-only</h3><p>To avoid spam, we require that you subscribe before you can
  post to a mailing list.
  Alternatively, you can post to the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
  <a class="ulink" href="https://sourceforge.net/p/clisp/discussion/3816/" target="_top">web
   forum</a> and your message will be forwarded to
  the <a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-list/">clisp-list</a> mailing list.
  If you read a list on <a class="ulink" href="http://gmane.org" target="_top">Gmane</a>
  and do not want to receive it also by e-mail, you can subscribe to
  it using the aforementioned web interface and then disable mail
  delivery.</p><p>Alternatively, you can ask on
  <a class="ulink" href="http://stackoverflow.com/questions/tagged/clisp" target="_top">StackOverflow</a>
  with tags <code class="literal">clisp</code> and/or <code class="literal">common-lisp</code>.
</p></div></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-mailing-lists"></a><a id="faq-mailing-lists-q"></a><p><strong>A.1.1.6.</strong></p></td><td align="left" valign="top"><p>Which mailing lists should I subscribe to?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>Cross-posting in the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
  <a class="ulink" href="https://sourceforge.net/p/clisp/mailman/" target="_top">mailing lists</a>
  is very actively discouraged and is virtually non-existent,
  thus you can subscribe to all mailing lists that are relevant to you
  without getting duplicate messages:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-announce/">clisp-announce</a></span></dt><dd>Extremely low-level moderated list, you should
    definitely subscribe to this list if you have any interest in <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a>
    or <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> whatsoever.</dd><dt><span class="term"><a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-list/">clisp-list</a></span></dt><dd>Subscribe to this list of you use <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> and want
    to ask (and answer!) questions. If you subscribe to this list, you
    probably want to subscribe to <a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-announce/">clisp-announce</a> too.
 </dd><dt><span class="term"><a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-devel/">clisp-devel</a></span></dt><dd>Subscribe to this list if you want to influence
    <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> developments; <a class="ulink" href="https://www.mercurial-scm.org/" target="_top">Mercurial</a> commit notes go here (as a daily digest).
    If you subscribe to this list, you probably want to subscribe
    to <a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-list/">clisp-list</a>
    <span class="strong"><strong>and</strong></span> <a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-announce/">clisp-announce</a> too.</dd></dl></div></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-rejected"></a><a id="faq-rejected-q"></a><p><strong>A.1.1.7.</strong></p></td><td align="left" valign="top"><p>Why
   is my mail to a mailing list rejected?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> mailing lists get a lot of spam, so the
  maintainers have to take care to protect the users.  If you get a note
  that <span class="quote">“<span class="quote">your message is held for moderator's approval</span>”</span>, you
  can safely <span class="strong"><strong>assume that it went
   to <code class="filename">/dev/null</code></strong></span>
  and try again, noting the following:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-announce/">clisp-announce</a></span></dt><dd>do not mail here without a prior discussion
    on <a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-devel/">clisp-devel</a>
    or <a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-list/">clisp-list</a></dd><dt><span class="term"><a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-devel/">clisp-devel</a></span></dt><dd>subscriber-only, you <span class="strong"><strong>must</strong></span> post
    from a <span class="strong"><strong>subscribed address</strong></span>,
    no exceptions (see <a class="link" href="#faq-help" title="A.1.1.5.">above</a>)
 </dd><dt><span class="term"><a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-list/">clisp-list</a></span></dt><dd><p>used to be the only open list (it is closed now), so
    it is filtered especially aggressively:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">no <a class="rfc" href="http://www.ietf.org/rfc/rfc2045.txt"><code>MIME</code></a> mail (no <a class="ulink" href="http://www.w3.org/MarkUp/" target="_top">HTML</a> formatting, no
       attachments - send the URL instead)</li><li class="listitem">the list address must be in <code class="literal">CC</code>
       or <code class="literal">TO</code>, not <code class="literal">BCC</code>.
     </li><li class="listitem">do not mention <span class="quote">“<span class="quote">virgin</span>”</span>,
       <span class="quote">“<span class="quote">penis</span>”</span> or <span class="quote">“<span class="quote">viagra</span>”</span> in
       the <code class="literal">Subject</code> line.</li></ul></div></dd></dl></div><p>If you do not like this policy, please volunteer to maintain the
  mailing lists - you will be required to go through all the
  <span class="quote">“<span class="quote">held for moderator's approval</span>”</span> mail and approve/discard
  as appropriate at least twice a day.</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-bugs"></a><a id="faq-bugs-q"></a><p><strong>A.1.1.8.</strong></p></td><td align="left" valign="top"><p>How do I
   report bugs?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p><a href="clisp.html#bugs" class="olink">Patiently</a>!
</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-contrib"></a><a id="faq-contrib-q"></a><p><strong>A.1.1.9.</strong></p></td><td align="left" valign="top"><p>How
   do I help?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>Please read <a class="xref" href="#extend" title="Chapter 36. Extending CLISP Core">Chapter 36, <em>Extending <span class="command"><strong>CLISP</strong></span> Core</em></a> and submit your patch,
  together with a <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/ChangeLog"><code class="filename">src/ChangeLog</code></a>
  entry (see other entries there for inspiration),
  to <a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-devel/">clisp-devel</a> (if it is small) or
  <a class="ulink" href="https://sourceforge.net/p/clisp/patches/" target="_top">SourceForge patch tracker</a>.</p><p>See <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/CodingStyle"><code class="filename">src/CodingStyle</code></a> for the
  style one should follow.</p><p>The patch should be created using <a class="ulink" href="https://www.mercurial-scm.org/" target="_top">Mercurial</a>.</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-debug"></a><a id="faq-debug-q"></a><p><strong>A.1.1.10.</strong></p></td><td align="left" valign="top"><p>How do I
   debug <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p><a id="with-debug"></a><strong>Configuring for debugging. </strong>Passing <a href="impnotes.html#with-debug" class="olink"><code class="option">--with-debug</code></a> to the top-level <a class="ulink" href="http://www.gnu.org/software/autoconf/" target="_top"><span class="command"><strong>configure</strong></span></a> script does not
 just replace <code class="option">-O</code> with <code class="option">-g</code>
 in the <a class="ulink" href="http://gcc.gnu.org/" target="_top"><span class="command"><strong>gcc</strong></span></a> invocation, it also disables some optimizations
 (registers, assembly, generational <a href="impnotes.html#gc" class="olink">garbage-collect</a>or) and enables
 some <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/printf.html"><code class="function">printf</code></a> calls (mostly before error
 messages caused by system calls).
 This means that some bugs might be exhibited by the normal build but
 <span class="strong"><strong>not</strong></span> by the <a href="impnotes.html#with-debug" class="olink"><code class="option">--with-debug</code></a> one (and vice versa).
 If that is the case, please <a class="ulink" href="http://www.gnu.org/software/autoconf/" target="_top"><span class="command"><strong>configure</strong></span></a> normally but edit the
 <code class="filename">Makefile</code> and replace the <a class="ulink" href="http://gcc.gnu.org/" target="_top"><span class="command"><strong>gcc</strong></span></a> optimization
 options (<code class="option">-O</code> et al) with <code class="option">-g</code> before
 running <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/make.html"><span class="command"><strong>make</strong></span></a>.</p><p><a id="faq-debug-core"></a><strong>Debugging the core. </strong></p><pre class="screen">
<strong><code class="prompt">$</code></strong> ./configure <a href="impnotes.html#with-debug" class="olink"><code class="option">--with-debug</code></a> --cbc build-g
<strong><code class="prompt">$</code></strong> cd build-g
<strong><code class="prompt">$</code></strong> gdb lisp.run <em class="lineannotation"><span class="lineannotation">;; or lisp.exe on <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> and <a class="ulink" href="http://cygwin.com/" target="_top"><span class="platform">Cygwin</span></a></span></em>
<strong><code class="prompt">(gdb)</code></strong> boot
<strong><code class="prompt">(gdb)</code></strong> run
</pre><p><a id="faq-debug-module"></a><strong>Debugging
  module <code class="literal">foo</code>. </strong></p><pre class="screen">
<strong><code class="prompt">$</code></strong> ./configure <a href="impnotes.html#with-debug" class="olink"><code class="option">--with-debug</code></a> --with-module=foo --cbc build-g
<strong><code class="prompt">$</code></strong> cd build-g
<strong><code class="prompt">$</code></strong> gdb full/lisp.run <em class="lineannotation"><span class="lineannotation">;; or lisp.exe on <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> and <a class="ulink" href="http://cygwin.com/" target="_top"><span class="platform">Cygwin</span></a></span></em>
<strong><code class="prompt">(gdb)</code></strong> full
<strong><code class="prompt">(gdb)</code></strong> run</pre><p>
When debugging a <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>base</strong></span></a> module, use <span class="command"><strong>base</strong></span>
 instead of <span class="command"><strong>full</strong></span> and <span class="command"><strong>boot</strong></span> above.
</p><p><a id="faq-debug-gengc"></a><strong>The impact of generational <a href="impnotes.html#gc" class="olink">garbage-collect</a>or. </strong>If your <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> was built with generational <a href="impnotes.html#gc" class="olink">garbage-collect</a>or, you will see
 plenty of spurious segfaults (that's how the generational <a href="impnotes.html#gc" class="olink">garbage-collect</a>or
 works).  At the end of <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/.gdbinit"><code class="filename">src/.gdbinit</code></a>
 you will find the following suggested <a class="ulink" href="http://sources.redhat.com/gdb/" target="_top"><span class="command"><strong>gdb</strong></span></a> commands:
</p><pre class="programlisting">handle SIGSEGV noprint nostop
break sigsegv_handler_failed</pre><p>
which will stop execution on a <span class="emphasis"><em>dangerous</em></span> segfault.
You can find out whether this is needed by examining the output of the
following command:
</p><pre class="screen"><strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp.html#clisp" class="olink">clisp</a></strong></span> --version | grep GENERATIONAL_GC</pre><p>
</p><p><a id="faq-debug-gdbinit"></a><strong>Useful commands. </strong>You are encouraged to make use of commands defined in
 <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/.gdbinit"><code class="filename">src/.gdbinit</code></a>,
 such as</p><table border="0" summary="Simple list" class="simplelist"><tr><td><span class="command"><strong>boot</strong></span></td><td><span class="command"><strong>run_mod_test</strong></span></td><td><span class="command"><strong>xout</strong></span></td></tr><tr><td><span class="command"><strong>base</strong></span></td><td><span class="command"><strong>run_all_tests</strong></span></td><td><span class="command"><strong>zout</strong></span></td></tr><tr><td><span class="command"><strong>full</strong></span></td><td><span class="command"><strong>run_ansi_tests</strong></span></td><td><span class="command"><strong>zbacktrace</strong></span></td></tr><tr><td><span class="command"><strong>run_test</strong></span></td><td><span class="command"><strong>run_ansi_tests_compiled</strong></span></td><td> </td></tr></table><p>and others; <span class="command"><strong>help <em class="replaceable"><code>command</code></em></strong></span> in <a class="ulink" href="http://sources.redhat.com/gdb/" target="_top"><span class="command"><strong>gdb</strong></span></a>
  will tell you what <em class="replaceable"><code>command</code></em> does.</p><p><a id="faq-debug-macros"></a><strong>Macros. </strong><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> makes heavy use of <a class="ulink" href="http://gcc.gnu.org/onlinedocs/cpp/" target="_top"><span class="command"><strong>cpp</strong></span></a> macros
  (e.g., <code class="function">pushSTACK</code>), which can complicate debugging
  in <a class="ulink" href="http://sources.redhat.com/gdb/" target="_top"><span class="command"><strong>gdb</strong></span></a>.  The macros are defined
  in <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/lispbibl.d"><code class="filename">src/lispbibl.d</code></a>, but the maze
  of conditionals may be hard to navigate. If you are using <a class="ulink" href="http://gcc.gnu.org/" target="_top"><span class="command"><strong>gcc</strong></span></a>, you
  can do <a class="unix" href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/make.html"><span class="command"><strong>make lispbibl.h</strong></span></a> and then
  examine the definitions in the generated <code class="filename">lispbibl.h</code>.
  See also bottom of <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/spvw_debug.d"><code class="filename">src/spvw_debug.d</code></a>.
</p><p><a id="faq-debug-binary-search"></a><strong>Binary Search in Time. </strong>When you encounter a <span class="emphasis"><em>regression error</em></span> (i.e.,
something worked in a previous version of <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>, but does not work in
the current version) which we cannot reproduce, we will often ask you to
figure out which specific <a class="ulink" href="https://www.mercurial-scm.org/" target="_top">Mercurial</a> commit introduced it.
The way to figure that out is to use <span class="command"><strong>hg bisect</strong></span>.
</p></td></tr><tr class="qandadiv"><td align="left" valign="top" colspan="2"><h4 class="title"><a id="faq-menorah"></a>A.1.2. Logo</h4></td></tr><tr class="toc"><td align="left" valign="top" colspan="2"><dl><dt>A.1.2.1. <a href="#faq-menorah-why">Why
   is CLISP using menorah as the logo?</a></dt><dt>A.1.2.2. <a href="#faq-menorah-current">Shouldn't the logo be changed now due to the current
   political developments in the Middle East?</a></dt><dt>A.1.2.3. <a href="#faq-menorah-other">Aren't there other political issues of concern?</a></dt><dt>A.1.2.4. <a href="#faq-menorah-users">Aren't you afraid of losing some users who are offended by
   the logo?</a></dt><dt>A.1.2.5. <a href="#faq-menorah-unprofessional">Using software to
   promote a political agenda is unprofessional!</a></dt></dl></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-menorah-why"></a><a id="faq-menorah-why-q"></a><p><strong>A.1.2.1.</strong></p></td><td align="left" valign="top"><p>Why
   is <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> using menorah as the logo?</p></td></tr><tr class="answer"><td align="left" valign="top"><p><strong>Whimsical</strong></p></td><td align="left" valign="top"><p>If you must have some answer and you do not care whether it is
  correct or not, you may simply think that <a class="ulink" href="https://common-lisp.net" target="_top"><span class="command"><strong>Common Lisp</strong></span></a> brings
  the <span class="emphasis"><em>Light</em></span> to a programmer, and <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> is a
  vehicle that carries the <span class="emphasis"><em>Light</em></span>.</p><p>Accordingly, <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> enables you to <span class="emphasis"><em>see</em></span> the
  truth, thus you can pronounce it as <span class="emphasis"><em>see-lisp</em></span>.
  Alternatively, if you are a <span class="emphasis"><em>seasoned</em></span> expert,
  you might pronounce it as <span class="emphasis"><em>sea-lisp</em></span>.</p></td></tr><tr class="answer"><td align="left" valign="top"><p><strong>Historical</strong></p></td><td align="left" valign="top"><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> has been using the menorah for the logo since the project was
   first started in the late 1980-ies by Bruno Haible and Michael Stoll.
   This <span class="emphasis"><em>probably</em></span> reflects the authors' affection
   toward the Jewish people, Judaism or the State of Israel
   (neither of the two original authors is Jewish by birth).
   You may ask the original authors for details yourself.
   Both of them are very busy though, so do not expect a prompt reply.
 </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-menorah-current"></a><a id="faq-menorah-current-q"></a><p><strong>A.1.2.2.</strong></p></td><td align="left" valign="top"><p>Shouldn't the logo be changed now due to the current
   political developments in the Middle East?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>The <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> developers, both the original creators and the
  current maintainers, do not subscribe to the mainstream view that
  blames the Jews for everything from high oil prices and Islamic
  extremism to El Niño and global warming (or cooling, whatever
  the looming disaster du jour is).</p><p>Moreover, today, when Jews are being pushed out of the American
  and European academic institutions with various obscene
  <a class="ulink" href="http://www.adl.org/israel-international/m/bds/" target="_top">boycott</a>
  and <a class="ulink" href="http://www.divestmentwatch.com/" target="_top">divestment</a>
  campaigns, it is crucial for all of us to stand together against
  the resurgence of Nazism.</p><p>For more information, please see:
 </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="ulink" href="http://www.camera.org/" target="_top">Committee for
     Accuracy in Middle East Reporting in America</a></li><li class="listitem"><a class="ulink" href="http://www.iris.org.il/" target="_top">Information
     Regarding Israel's Security</a></li><li class="listitem"><a class="ulink" href="http://www.memri.org/" target="_top">Middle East
     Media Research Institute</a></li><li class="listitem"><a class="ulink" href="http://www.mideasttruth.com/" target="_top">YES to
     peace, NO to terror</a></li><li class="listitem"><a class="ulink" href="http://www.mideasttruth.com/links.html" target="_top">More
     links</a></li></ul></div></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-menorah-other"></a><a id="faq-menorah-other-q"></a><p><strong>A.1.2.3.</strong></p></td><td align="left" valign="top"><p>Aren't there other political issues of concern?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>Yes, there are!  For example, in 1989 the
  <a class="ulink" href="http://sds.podval.org/commies.html" target="_top">communist</a>
  government of the <a class="ulink" href="http://www.chinasupport.net/" target="_top">People's
   Republic of China</a> murdered some 3000+
  student human rights protesters at the Tienanmen square in Beijing,
  and people appear to have already forgotten this crime.
  A note to that effect was kept in the file
  <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/timezone.lisp"><code class="filename">src/timezone.lisp</code></a>
  until 2002, when it was decided that is was not visible enough there
  and it was moved here.</p><p>We also oppose <a class="ulink" href="http://swpat.ffii.org/" target="_top">software
   patents</a> and support other liberal (i.e., pro-liberty) causes.</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-menorah-users"></a><a id="faq-menorah-users-q"></a><p><strong>A.1.2.4.</strong></p></td><td align="left" valign="top"><p>Aren't you afraid of losing some users who are offended by
   the logo?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>Do you have in mind people like
  <a class="ulink" href="https://groups.google.com/d/msg/gnu.emacs.help/R7wEPCJXuaI/r-5lmxlY9vQJ" target="_top">this</a> one?
  Good riddance!</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-menorah-unprofessional"></a><a id="faq-menorah-unprofessional-q"></a><p><strong>A.1.2.5.</strong></p></td><td align="left" valign="top"><p>Using software to
   promote a political agenda is unprofessional!</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>Expressing their opinion is a perfectly natural thing for the
  authors, be it artistic preferences, political views or religious beliefs.
  The use of the menorah has its roots somewhere between these areas,
  and the authors are proud to display it.
  If you are unlucky enough to have lost the freedom to express your
  opinion, due to the constraints of a government, society, religion,
  or expectations of <span class="quote">“<span class="quote">professional relationships</span>”</span>,
  the Free World condoles with you.
  The authors of <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> are not operating under such constraints.
  If you are unhappy about their artistic preferences, political views or
  religious beliefs, you are free to ignore them.</p><p>Many scientists have been doing art, politics and religion.
  René Descartes and Isaak Newton combined mathematics and Christianity.
  Albert Einstein helped the U.S. to counter the danger of an atomic bomb
  in the hands of the Nazis.
  Bram Moolenaar, the author of <a class="ulink" href="http://www.vim.org/" target="_top">VIM</a>,
  promotes charitable donations to Uganda.</p></td></tr><tr class="qandadiv"><td align="left" valign="top" colspan="2"><h3 class="title"><a id="faq-run"></a>A.2. Running <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a></h3></td></tr><tr class="toc"><td align="left" valign="top" colspan="2"><dl><dt>A.2.1. <a href="#faq-defun">Why are floats printed in binary?</a></dt><dt>A.2.2. <a href="#faq-ide">Where is the IDE?</a></dt><dt>A.2.3. <a href="#faq-opt">What are the
   command line arguments?</a></dt><dt>A.2.4. <a href="#faq-debugger">How
   do I get out of the debugger?</a></dt><dt>A.2.5. <a href="#faq-ext">What CLISP
   extensions are available?</a></dt><dt>A.2.6. <a href="#faq-rc">Where is the
   init (“RC”) file on my platform?</a></dt><dt>A.2.7. <a href="#faq-modules">Where
   are the modules with which I built CLISP?</a></dt><dt>A.2.8. <a href="#faq-gui">How do I create
   a GUI
   for my CLISP program?</a></dt></dl></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-defun"></a><a id="faq-defun-q"></a><p><strong>A.2.1.</strong></p></td><td align="left" valign="top"><p>Why are floats printed in binary?</p><p>Where is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defun.html" target="_top"><code class="function">DEFUN</code></a>?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>Pass <code class="option"><a href="clisp.html#opt-memfile" class="olink">-M</a></code> to the <a href="clisp.html#runtime" class="olink">runtime</a> (<code class="filename">lisp.run</code>
  or <code class="filename">lisp.exe</code>).
  Or, better yet, use the driver <code class="filename">clisp</code> (or
  <code class="filename">clisp.exe</code>) instead of invoking the <a href="clisp.html#runtime" class="olink">runtime</a>
  directly.</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-ide"></a><a id="faq-ide-q"></a><p><strong>A.2.2.</strong></p></td><td align="left" valign="top"><p>Where is the <acronym class="acronym" title="Integrated Development Environment">IDE</acronym>?</p></td></tr><tr class="answer"><td align="left" valign="top"><p><strong><a class="ulink" href="http://www.gnu.org/software/emacs/" target="_top">Emacs</a>-based</strong></p></td><td align="left" valign="top"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="ulink" href="http://www.gnu.org/software/emacs/manual/html_node/emacs/External-Lisp.html" target="_top"><code class="function">run-lisp</code></a></li><li class="listitem"><a class="ulink" href="http://common-lisp.net/project/slime/" target="_top">SLIME</a></li><li class="listitem"><a class="ulink" href="http://sourceforge.net/projects/ilisp/" target="_top">ILISP</a></li><li class="listitem"><a class="ulink" href="http://cl-cookbook.sourceforge.net/windows.html" target="_top">The Common Lisp Cookbook</a></li></ul></div></td></tr><tr class="answer"><td align="left" valign="top"><p><strong>non-<a class="ulink" href="http://www.gnu.org/software/emacs/" target="_top">Emacs</a>-based</strong></p></td><td align="left" valign="top"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="" href="http://www.google.com/search?q=VisualCLisp">VisualCLisp</a></li><li class="listitem"><a class="ulink" href="http://jabberwocky.sourceforge.net/" target="_top">Jabberwocky</a></li><li class="listitem"><a class="ulink" href="http://gclisp.sourceforge.net/" target="_top">GClisp</a></li><li class="listitem"><a class="ulink" href="http://common-lisp.net/project/phemlock/" target="_top">Portable Hemlock</a></li></ul></div></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-opt"></a><a id="faq-opt-q"></a><p><strong>A.2.3.</strong></p></td><td align="left" valign="top"><p>What are the
   command line arguments?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>See <a href="clisp.html#clisp" class="olink"><span class="refentrytitle">clisp</span>(1)</a>.</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-debugger"></a><a id="faq-debugger-q"></a><p><strong>A.2.4.</strong></p></td><td align="left" valign="top"><p>How
   do I get out of the debugger?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>See <a class="xref" href="#repl" title="25.1. Top Level Loop sec_25-1-1">Section 25.1, “Top Level Loop   sec_25-1-1”</a>.</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-ext"></a><a id="faq-ext-q"></a><p><strong>A.2.5.</strong></p></td><td align="left" valign="top"><p>What <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
   extensions are available?</p></td></tr><tr class="answer"><td align="left" valign="top"><p><strong>bundled</strong></p></td><td align="left" valign="top"><p>Quite a few modules are
  <a class="link" href="#included-modules" title="32.2.9. Modules included in the source distribution">included</a> with <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>,
  pass <code class="option">--with-module=...</code> to <a class="ulink" href="http://www.gnu.org/software/autoconf/" target="_top"><span class="command"><strong>configure</strong></span></a>
  to build them and see <a class="xref" href="#faq-modules" title="A.2.7.">Q: A.2.7</a>.</p></td></tr><tr class="answer"><td align="left" valign="top"><p><strong>3rd party</strong></p></td><td align="left" valign="top"><p>See the <span class="emphasis"><em>incomplete</em></span> list of
  <a class="ulink" href="http://clisp.org/resources.html#software" target="_top">Common
    Lisp software running in <span class="command"><strong>CLISP</strong></span></a>.</p></td></tr><tr class="answer"><td align="left" valign="top"><p><strong><acronym class="acronym" title="Do It Yourself">DIY</acronym></strong></p></td><td align="left" valign="top"><p>See <a class="xref" href="#modules" title="32.2. External Modules">Section 32.2, “External Modules”</a> and <a class="xref" href="#dffi" title="32.3. The Foreign Function Call Facility">Section 32.3, “The Foreign Function Call Facility”</a>
  for information on how to interface with external <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a> libraries.
</p></td></tr><tr class="answer"><td align="left" valign="top"><p><strong><a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a></strong></p></td><td align="left" valign="top"><div class="itemizedlist"><p class="title"><strong>Very Frequently Asked!</strong></p><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> comes with
    <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/src/inspect.lisp"><code class="filename">src/inspect.lisp</code></a>
    which implements a rudimentary <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> server</li><li class="listitem"><a class="ulink" href="http://clocc.sourceforge.net/clocc/src/donc/http.lisp" target="_top">CLOCC/src/donc/</a> has an <a class="ulink" href="http://www.w3.org/Protocols/" target="_top"><span class="command"><strong>HTTP</strong></span></a> server</li><li class="listitem"><a class="ulink" href="http://clocc.sourceforge.net/clocc/src/cllib/url.lisp" target="_top">CLOCC/src/cllib/</a> handles URLs</li><li class="listitem"><a class="ulink" href="http://www.cliki.net/mod_lisp" target="_top">mod_lisp</a>
    hooks lisp into <a class="ulink" href="http://www.apache.org/" target="_top">Apache</a></li></ul></div><p>Both <a class="ulink" href="http://allegroserve.sourceforge.net/" target="_top">AllegroServe</a>
  and <a class="ulink" href="https://en.wikipedia.org/wiki/CL-HTTP" target="_top">CL-HTTP</a>
  require <a class="link" href="#mt" title="32.5. Multiple Threads of Execution">multithreading</a> and do not work
  with <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> yet.</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-rc"></a><a id="faq-rc-q"></a><p><strong>A.2.6.</strong></p></td><td align="left" valign="top"><p>Where is the
   init (<span class="quote">“<span class="quote">RC</span>”</span>) file on my platform?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>Read the file <code class="filename">&lt;clisp.html#opt-norc&gt;</code>
  in your build directory or binary distribution (this is the version of
  the user manual <a href="clisp.html#clisp" class="olink"><span class="refentrytitle">clisp</span>(1)</a> for your platform).</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-modules"></a><a id="faq-modules-q"></a><p><strong>A.2.7.</strong></p></td><td align="left" valign="top"><p>Where
   are the modules with which I built <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>In the <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>full</strong></span></a> <a href="impnotes.html#linkset" class="olink">linking set</a>. Run <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> like this:
  </p><pre class="screen"><strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp.html#clisp" class="olink">clisp</a></strong></span> <code class="option"><a href="clisp.html#opt-link-set" class="olink">-K</a></code> full</pre><p>Unless your <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> was configured with option <code class="option"><a href="impnotes.html#mod-dynload" class="olink">--without-dynamic-modules</a></code>, you
  should instead use <code class="code">(<a href="impnotes.html#require" class="olink"><code class="function">REQUIRE</code></a> <em class="replaceable"><code>name</code></em>)</code> where <em class="replaceable"><code>name</code></em> is
  a <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_string.html" target="_top"><code class="classname">STRING</code></a>, e.g., <span class="quote">“<span class="quote"><span class="module"><a class="filename" href="#rawsock" title="33.17. Raw Socket Access"><code class="filename">rawsock</code></a></span></span>”</span>, or <span class="quote">“<span class="quote">clx</span>”</span>
  (for either <span class="module"><a href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/clx/new-clx/"><code class="filename">clx/new-clx</code></a></span> or <span class="module"><a href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/clx/mit-clx/"><code class="filename">clx/mit-clx</code></a></span>, whichever is installed),
  or <span class="quote">“<span class="quote">linux</span>”</span> (for <span class="module"><a href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/modules/bindings/glibc/"><code class="filename">bindings/glibc</code></a></span>) etc.
  This is more reliable because the <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>full</strong></span></a> <a href="impnotes.html#linkset" class="olink">linking set</a> may include many modules
  which you do not need and, in fact, <span class="strong"><strong>cannot</strong></span> use because they require
  external libraries not installed on your system.</p><p>Making <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>base</strong></span></a> the default <a href="impnotes.html#linkset" class="olink">linking set</a> has some advantages:</p><div class="variablelist"><dl class="variablelist"><dt><span class="term">Shared Library Hell</span></dt><dd>Avoid problems when a module requires a shared
      library, and that shared library is not present (or is present but
      with wrong version) on your system.</dd><dt><span class="term">Smaller Images Are Faster</span></dt><dd>Adding things to the heap increases working
      set size causing a slowdown, which is especially important for
      small to medium applications.</dd><dt><span class="term">Uniform User Experience</span></dt><dd>Composition of the <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>full</strong></span></a> <a href="impnotes.html#linkset" class="olink">linking set</a> is up to the
      packager, while <a href="impnotes.html#base-modules" class="olink"><span class="command"><strong>base</strong></span></a> is the same on all platforms.
 </dd></dl></div><p>See <a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-list/">clisp-list</a> for more information
  (<a class="gmane" href="http://article.gmane.org/gmane.lisp.clisp.general/8691"><code>Gmane/general/8691</code></a>/<a class="ulink" href="https://sourceforge.net/p/clisp/mailman/message/11678654/" target="_top">https://sourceforge.net/p/clisp/mailman/message/11678654/</a>).</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-gui"></a><a id="faq-gui-q"></a><p><strong>A.2.8.</strong></p></td><td align="left" valign="top"><p>How do I create
   a <acronym class="acronym" title="Graphical User Interface">GUI</acronym>
   for my <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> program?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>Use module <span class="module"><a class="filename" href="#gtk" title="33.20. GTK Interface"><code class="filename">gtk2</code></a></span>: create <code class="filename">ui.glade</code>
   with <a class="ulink" href="http://glade.gnome.org/" target="_top">Glade</a>, then do</p><pre class="screen">
<strong><code class="prompt">$</code></strong> ./configure --with-module=gtk2 --cbc build-gtk
<strong><code class="prompt">$</code></strong> ./build-gtk/clisp <code class="option"><a href="clisp.html#opt-link-set" class="olink">-K</a></code> full <code class="option"><a href="clisp.html#opt-exec-expr" class="olink">-x</a></code> '(gtk:run-glade-file "ui.glade")'</pre><p>There are many other options,
  see <a class="ulink" href="http://clisp.org/resources.html#software" target="_top">"Common
    Lisp software running in <span class="command"><strong>CLISP</strong></span>"</a>.</p></td></tr><tr class="qandadiv"><td align="left" valign="top" colspan="2"><h3 class="title"><a id="faq-delivery"></a>A.3. Application Delivery</h3></td></tr><tr class="toc"><td align="left" valign="top" colspan="2"><dl><dt>A.3.1. <a href="#faq-exec">How do I
   create an executable file with all my code in it?</a></dt><dt>A.3.2. <a href="#faq-licensing">When
   I deliver my application with CLISP, does it have to be covered by
   the GNU GPL?</a></dt></dl></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-exec"></a><a id="faq-exec-q"></a><p><strong>A.3.1.</strong></p></td><td align="left" valign="top"><p>How do I
   create an executable file with all my code in it?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>Use <a href="impnotes.html#image" class="olink"><code class="function">EXT:SAVEINITMEM</code></a>, see also <a class="xref" href="#quickstart" title="32.6. Quickstarting delivery with CLISP">Section 32.6, “Quickstarting delivery with <span class="command"><strong>CLISP</strong></span>”</a>.
</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-licensing"></a><a id="faq-licensing-q"></a><p><strong>A.3.2.</strong></p></td><td align="left" valign="top"><p>When
   I deliver my application with <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>, does it have to be covered by
   the <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/copyleft/gpl.html" target="_top">GPL</a>?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>Not necessarily.</p><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> is <a class="ulink" href="http://www.gnu.org/philosophy/free-sw.html" target="_top">Free
  Software</a>, covered by the <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/copyleft/gpl.html" target="_top">GPL</a>, with special
 terms governing the distribution of applications that run in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.
 The precise terms can be found in the
 <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/COPYRIGHT"><code class="filename">COPYRIGHT</code></a>
 file contained in the source and binary distributions of <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.
 Here is an informal clarification of what these terms mean in practice.
 Please refer to the said <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/COPYRIGHT"><code class="filename">COPYRIGHT</code></a>
 file when in doubt.</p><p>In many cases, <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> does not force an application to be covered
 by the <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/copyleft/gpl.html" target="_top">GPL</a>. Nevertheless, we encourage you to release your software
 under an open source license. The benefits of such a license for
 your users are numerous, in particular they are free to modify the
 application when their needs/requirements change, and they are free to
 recompile the application when they upgrade their machine or operating
 system.</p><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <span class="emphasis"><em>extensions</em></span>, i.e. programs which need
 to access non-portable <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> internal symbols (in the packages
 <a class="link" href="#sys-pac"><strong class="package"><span class="quote">“<span class="quote">SYSTEM</span>”</span></strong></a>, <a class="link" href="#classes" title="4.2. Classes sec_4-3"><strong class="package"><span class="quote">“<span class="quote">CLOS</span>”</span></strong></a>, <a class="link" href="#dffi" title="32.3. The Foreign Function Call Facility"><strong class="package"><span class="quote">“<span class="quote">FFI</span>”</span></strong></a>, etc), must be covered by <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/copyleft/gpl.html" target="_top">GPL</a>
 as well.</p><p>Other programs running in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> have to or need not to be placed
 under <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/copyleft/gpl.html" target="_top">GPL</a>, depending on their distribution form:

</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">Programs distributed as Lisp source or <code class="filename">#P".fas"</code>
   files can be distributed without restrictions coming from <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.
 </li><li class="listitem">Programs distributed as <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a href="impnotes.html#image" class="olink">memory image</a>s can be
  distributed only if accompanied with the non-<a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <code class="filename">#P".fas"</code> files
  which make up the <a href="impnotes.html#image" class="olink">memory image</a>, and a <code class="filename">Makefile</code> (or clear textual
  instructions) for rebuilding the <a href="impnotes.html#image" class="olink">memory image</a>.</li><li class="listitem">If you need to distribute a modified <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
  executable (for example, incorporating additional <a href="impnotes.html#modules" class="olink">module</a>s written
  in <a class="ulink" href="http://c-faq.com/" target="_top"><span class="command"><strong>C</strong></span></a>), you must distribute its full source under <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://www.gnu.org/copyleft/gpl.html" target="_top">GPL</a>.
  If you are not satisfied with this, you can instead put the additional
  <a href="impnotes.html#modules" class="olink">module</a>s into a separate (non-<a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>) program, with which your Lisp
  program will communicate via <a class="link" href="#socket" title="32.4. Socket Streams"><code class="classname">SOCKET:SOCKET-STREAM</code></a>s.</li></ul></div></td></tr><tr class="qandadiv"><td align="left" valign="top" colspan="2"><h3 class="title"><a id="faq-trouble"></a>A.4. Troubles</h3></td></tr><tr class="toc"><td align="left" valign="top" colspan="2"><dl><dt>A.4.1. <a href="#faq-bin-distrib">Where
   is the binary distribution for my platform?</a></dt><dt>A.4.2. <a href="#faq-bin-distrib-prev">But a previous release had a binary
   distribution for my platform, why does not the current one?</a></dt><dt>A.4.3. <a href="#faq-build">Why does not
   CLISP build on my platform?</a></dt><dt>A.4.4. <a href="#faq-with-prefix">
   Why is the --with-libsigsegv-prefix option ignored
   by the configure script on my 64-bit machine?</a></dt><dt>A.4.5. <a href="#faq-enc-err">What do charset errors mean?</a></dt><dt>A.4.6. <a href="#faq-rl-tab">What does
   this message mean: “Display all 1259
     possibilities? (y or n)”</a></dt><dt>A.4.7. <a href="#faq-no-rl">Why does
   not command line editing work?</a></dt><dt>A.4.8. <a href="#faq-stack">How do I
   avoid stack overflow?</a></dt><dt>A.4.9. <a href="#faq-self-mod">Why does my function return different values on each
   invocation and then hangs forever?</a></dt><dt>A.4.10. <a href="#faq-fp">Is floating point arithmetic broken?</a></dt><dt>A.4.11. <a href="#faq-random">Is RANDOM broken?</a></dt><dt>A.4.12. <a href="#faq-pp-newline">Why is an extra line break
   inserted by the pretty printer?</a></dt><dt>A.4.13. <a href="#faq-warning">How do I disable this annoying
   warning?</a></dt><dt>A.4.14. <a href="#faq-scope">Why does DEFVAR affect previously defined lexical closures?</a></dt><dt>A.4.15. <a href="#faq-bad-error">The error message is not helpful!</a></dt><dt>A.4.16. <a href="#faq-other-problem">Why is the function FOO
   broken?!</a></dt></dl></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-bin-distrib"></a><a id="faq-bin-distrib-q"></a><p><strong>A.4.1.</strong></p></td><td align="left" valign="top"><p>Where
   is the binary distribution for my platform?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>The <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> maintainers do not offer <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> binary
  distributions, we believe that software packagers specializing on a
  particular platform are in a better position to provide quality binaries.
  Indeed, the section <span class="quote">“<span class="quote">Get CLISP</span>”</span> on the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>'s home
  page points to <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> packages for all major <a class="ulink" href="https://www.kernel.org/" target="_top"><span class="platform">Linux</span></a> and <a class="ulink" href="http://www.bsd.org/" target="_top"><span class="platform">*BSD</span></a>
  variants.</p><p>The only exception is <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> for which there is no centralized
  packager: <span class="emphasis"><em>usually</em></span>, after each <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> release,
  a <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> user <span class="emphasis"><em>volunteers</em></span> to build a <a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a>
  binary package, which we then distribute at
  <a class="ulink" href="https://sourceforge.net/projects/clisp/files/" target="_top">https://sourceforge.net/projects/clisp/files/</a>.
</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-bin-distrib-prev"></a><a id="faq-bin-distrib-prev-q"></a><p><strong>A.4.2.</strong></p></td><td align="left" valign="top"><p>But a previous release <span class="emphasis"><em>had</em></span> a binary
   distribution for my platform, why does not the current one?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>It was probably contributed by a user who did not (yet?)
  contribute a binary distribution for the current release. You can
  find out who contributed a specific binary distribution by looking at
  the release notes in the <a class="ulink" href="https://sourceforge.net" target="_top">SourceForge</a>
  <a class="ulink" href="https://sourceforge.net/projects/clisp/files/" target="_top">Files</a> section.</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-build"></a><a id="faq-build-q"></a><p><strong>A.4.3.</strong></p></td><td align="left" valign="top"><p>Why does not
   <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> build on my platform?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>Please see file
  <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/unix/PLATFORMS"><code class="filename">unix/PLATFORMS</code></a> in your source
  distribution for information about some known troublesome platforms
  as well as instructions on porting <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> to new platforms.</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-with-prefix"></a><a id="faq-with-prefix-q"></a><p><strong>A.4.4.</strong></p></td><td align="left" valign="top"><p>
   Why is the <code class="option">--with-libsigsegv-prefix</code> option ignored
   by the <a class="ulink" href="http://www.gnu.org/software/autoconf/" target="_top"><span class="command"><strong>configure</strong></span></a> script on my 64-bit machine?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>See a note on <span class="quote">“<span class="quote">bi-arch systems</span>”</span> in section 2 of
 <a class="clisp-cvs" href="https://sourceforge.net/p/clisp/clisp/ci/tip/tree/unix/INSTALL"><code class="filename">unix/INSTALL</code></a> in your source distribution
  (for the impatient: pass <code class="option">--libdir=='${exec_prefix}/lib64'</code>
    to the <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://libsigsegv.sourceforge.net/" target="_top">libsigsegv</a> <a class="ulink" href="http://www.gnu.org/software/autoconf/" target="_top"><span class="command"><strong>configure</strong></span></a>).</p><p>See these threads which discuss the situation in depth:</p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="ulink" href="http://thread.gmane.org/gmane.comp.lib.gnulib.bugs/14565" target="_top">http://thread.gmane.org/gmane.comp.lib.gnulib.bugs/14565</a>/<a class="ulink" href="https://lists.gnu.org/archive/html/bug-gnulib/2008-09/msg00070.html" target="_top">https://lists.gnu.org/archive/html/bug-gnulib/2008-09/msg00070.html</a></td></tr><tr><td><a class="ulink" href="http://thread.gmane.org/gmane.comp.sysutils.autoconf.general/10827" target="_top">http://thread.gmane.org/gmane.comp.sysutils.autoconf.general/10827</a>/<a class="ulink" href="http://lists.gnu.org/archive/html/autoconf/2008-09/msg00059.html" target="_top">http://lists.gnu.org/archive/html/autoconf/2008-09/msg00059.html</a></td></tr></table></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-enc-err"></a><a id="faq-enc-err-q"></a><p><strong>A.4.5.</strong></p></td><td align="left" valign="top"><p>What do these error messages
    mean: <span class="quote">“<span class="quote"><code class="computeroutput">invalid byte #x94 in
    CHARSET:ASCII conversion</code></span>”</span> and
   <span class="quote">“<span class="quote"><code class="computeroutput">character #\u00B3 cannot be represented in the
    character set CHARSET:ASCII</code></span>”</span>?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>This means that you are trying to read (<span class="quote">“<span class="quote">invalid
 byte</span>”</span>) or write (<span class="quote">“<span class="quote">character cannot be represented</span>”</span>)
 a non-<a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a> character from (or to) a character stream which has
 <a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a> <a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a>. The default is described in
  <a href="clisp.html#opt-enc" class="olink"><code class="option">-E<em class="replaceable"><code>domain</code></em> <em class="replaceable"><code>encoding</code></em></code></a>.</p><p>This may also be caused by filesystem access.
 If you have files with names incompatible with your <a href="impnotes.html#path-enc" class="olink"><code class="varname">CUSTOM:*PATHNAME-ENCODING*</code></a>,
 filesystem access (e.g., <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_directory.html" target="_top"><code class="function">DIRECTORY</code></a>) will <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_signal.html" target="_top"><code class="function">SIGNAL</code></a> this <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_error.html" target="_top"><code class="classname">ERROR</code></a>.
 You will need to set <a href="impnotes.html#path-enc" class="olink"><code class="varname">CUSTOM:*PATHNAME-ENCODING*</code></a> or pass <code class="option"><a href="clisp.html#opt-enc" class="olink"><code class="option">-E<em class="replaceable"><code>domain</code></em> <em class="replaceable"><code>encoding</code></em></code></a></code> to <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.
 Using a <a class="link" href="#enc1-1" title="“1:1” encodings"><span class="quote">“<span class="quote">1:1</span>”</span> encoding</a>, such as <a class="link" href="#charset-UTF-16"><code class="constant">CHARSET:ISO-8859-1</code></a>,
 should help you avoid this error.</p><p>Note that this error may be signaled by the <span class="quote">“<span class="quote">Print</span>”</span>
 part of the <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_25-1-1.html">read-eval-print loop</a> and <span class="strong"><strong>not</strong></span> by the function you call.
 E.g., if file <code class="filename">"foo"</code> contains non-<a class="ulink" href="https://en.wikipedia.org/wiki/ASCII" target="_top"><span class="platform">ASCII</span></a> characters,
 you will see such an error when you type</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-open-file.html" target="_top"><code class="function">WITH-OPEN-FILE</code></a> (s "foo" :direction :input <a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a> <a class="link" href="#charset-UTF-16"><code class="constant">CHARSET:ISO-8859-1</code></a>)
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-line.html" target="_top"><code class="function">READ-LINE</code></a> s))
</pre><p> If instead you type </p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_with-open-file.html" target="_top"><code class="function">WITH-OPEN-FILE</code></a> (s "foo" :direction :input <a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a> <a class="link" href="#charset-UTF-16"><code class="constant">CHARSET:ISO-8859-1</code></a>)
  (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/spefor_setq.html" target="_top"><code class="function">SETQ</code></a> l (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_read-line.html" target="_top"><code class="function">READ-LINE</code></a> s))
  <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>)
</pre><p> <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> will just print <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a> and signal the error
 when you type <code class="literal">l</code>.</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-rl-tab"></a><a id="faq-rl-tab-q"></a><p><strong>A.4.6.</strong></p></td><td align="left" valign="top"><p>What does
   this message mean: <span class="quote">“<span class="quote"><code class="computeroutput">Display all 1259
     possibilities? (y or n)</code></span>”</span></p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> uses <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://tiswww.case.edu/php/chet/readline/readline.html" target="_top">readline</a> for command line editing and
   <a href="clisp.html#completion" class="olink">completion</a>.
   You get this <span class="quote">“<span class="quote">Display all 1259 possibilities</span>”</span> message
   (and sometimes many screens of symbols) when you
   hit <span class="keycode">TAB</span> too many times in an inappropriate place.
 <a href="clisp.html#opt-ilisp" class="olink">You can turn this feature
  off</a> if you are using <a class="ulink" href="http://www.gnu.org/software/emacs/" target="_top">Emacs</a>.  It is a good idea
 <a class="ulink" href="http://www.w3.org/MarkUp/html3/literal.html" target="_top">not</a> to
 use <span class="keycode">TAB</span>s in your code.</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-no-rl"></a><a id="faq-no-rl-q"></a><p><strong>A.4.7.</strong></p></td><td align="left" valign="top"><p>Why does
   not command line editing work?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>See <a class="xref" href="#readline" title="21.2.1. Command line editing with GNU readline">Section 21.2.1, “Command line editing with GNU readline”</a>.</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-stack"></a><a id="faq-stack-q"></a><p><strong>A.4.8.</strong></p></td><td align="left" valign="top"><p>How do I
   avoid stack overflow?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> has <a class="link" href="#vm" title="37.2. The virtual machine"><span class="emphasis"><em>two</em></span>
   stacks</a>, the <span class="quote">“<span class="quote">program stack</span>”</span> and the <span class="quote">“<span class="quote">lisp
   stack</span>”</span>, and both may occasionally overflow.</p></td></tr><tr class="answer"><td align="left" valign="top"><p><strong>Generic</strong></p></td><td align="left" valign="top"><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">You will always get a stack overflow when you try
    to print a <a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#circular">circular</a> object (<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_list.html" target="_top"><code class="classname">LIST</code></a>,
    <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/cla_structure-object.html" target="_top"><code class="classname">STRUCTURE-OBJECT</code></a>, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_vector.html" target="_top"><code class="classname">VECTOR</code></a> etc) and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-circlest.html" target="_top"><code class="varname">*PRINT-CIRCLE*</code></a> is <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_nil.html" target="_top"><code class="constant">NIL</code></a>.
    Just set <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-circlest.html" target="_top"><code class="varname">*PRINT-CIRCLE*</code></a> to <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>.</li><li class="listitem">You will always get a stack overflow on infinite
    recursion.</li><li class="listitem">Some simple functions (like
    <a class="ulink" href="http://en.wikipedia.org/wiki/Ackermann_function" target="_top">Ackermann's</a>)
    recurse more than you might expect and can run out of stack on
    relatively small inputs.</li><li class="listitem">Compiled code uses less stack (and memory) and is
    faster.</li><li class="listitem">If you really do need more Lisp stack, you can
    increase it by telling <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> to pre-allocate more memory using
    <code class="option"><a href="clisp.html#opt-memsize" class="olink">-m</a></code> or <a class="link" href="#make-thread"><code class="function">MT:MAKE-THREAD</code></a>.</li><li class="listitem">If you get a segmentation fault after (or instead
    of) a <span class="quote">“<span class="quote">program stack overflow</span>”</span> message, please make
    sure that you had <a class="ulink" href="https://www.gnu.org" target="_top">GNU</a> <a class="ulink" href="http://libsigsegv.sourceforge.net/" target="_top">libsigsegv</a> installed when you configured and
    built <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.</li></ul></div></td></tr><tr class="answer"><td align="left" valign="top"><p><strong>Specific</strong></p></td><td align="left" valign="top"><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://winehq.org/" target="_top"><span class="platform">Win32</span></a> platform only.</span></span></span></dt><dd><p>You have several option, use whichever is applicable
    to your situation:</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">modify the
       global <code class="filename">SYSTEM.INI</code></li><li class="listitem">modify the <code class="filename">PIF</code>
       that you use to invoke <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
       (<a class="gmane" href="http://article.gmane.org/gmane.lisp.clisp.general/4656"><code>Gmane/general/4656</code></a>/<a class="ulink" href="https://sourceforge.net/p/clisp/mailman/message/9033347/" target="_top">https://sourceforge.net/p/clisp/mailman/message/9033347/</a>)</li><li class="listitem">or set the program stack (of the run
       times <span class="command"><strong>base/lisp.exe</strong></span> or
       <span class="command"><strong>full/lisp.exe</strong></span>, <span class="strong"><strong>not</strong></span> the driver
       <span class="command"><strong>clisp.exe</strong></span>) using <span class="command"><strong>editbin</strong></span>
       (<a class="gmane" href="http://article.gmane.org/gmane.lisp.clisp.general/5523"><code>Gmane/general/5523</code></a>/<a class="ulink" href="https://sourceforge.net/p/clisp/mailman/message/9033144/" target="_top">https://sourceforge.net/p/clisp/mailman/message/9033144/</a>); you can find the
       current stack size using <span class="command"><strong>dumpbin</strong></span>.
 </li></ul></div></dd><dt><span class="term"><span class="plat-dep">Platform Dependent: <span class="plat-dep"><a class="ulink" href="http://www.unix.org/online.html" target="_top"><span class="strong"><strong>UNIX</strong></span></a> platform only.</span></span></span></dt><dd>Increase program stack with <span class="command"><strong>ulimit
     -s</strong></span> (or <span class="command"><strong>limit stacksize</strong></span> if you are using
    <a class="ulink" href="http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/" target="_top"><code class="literal">csh</code></a>) to at least 8 MB.
</dd></dl></div></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-self-mod"></a><a id="faq-self-mod-q"></a><p><strong>A.4.9.</strong></p></td><td align="left" valign="top"><p>Why does my function return different values on each
   invocation and then hangs forever?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>The following code modifies itself:
</p><pre class="programlisting">(defun my-func ()<strong>	; </strong><em class="lineannotation"><span class="lineannotation">modifies internal data!</span></em>
  (let ((var '(a b c)))
    (nconc var '(1 2 3))))</pre><p>
and will not work as one would naively expect:</p><pre class="programlisting">
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/spefor_setq.html" target="_top"><code class="function">SETQ</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stprint-circlest.html" target="_top"><code class="varname">*PRINT-CIRCLE*</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/convar_t.html" target="_top"><code class="constant">T</code></a>)
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_function-_a-expression.html" target="_top"><code class="function">FUNCTION-LAMBDA-EXPRESSION</code></a> #'my-func)
⇒ <code class="computeroutput">(LAMBDA NIL (DECLARE (SYSTEM::IN-DEFUN MY-FUNC))
 (BLOCK MY-FUNC (LET ((VAR '(A B C))) (NCONC VAR '(1 2 3)))))</code>
(my-func)<strong>	; </strong><em class="lineannotation"><span class="lineannotation">the first invocation</span></em>
⇒ <code class="computeroutput">(a b c 1 2 3)</code><strong>	; </strong><em class="lineannotation"><span class="lineannotation">modifies the internal data:</span></em>
(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_function-_a-expression.html" target="_top"><code class="function">FUNCTION-LAMBDA-EXPRESSION</code></a> #'my-func)
⇒ <code class="computeroutput">(LAMBDA NIL (DECLARE (SYSTEM::IN-DEFUN MY-FUNC))
 (BLOCK MY-FUNC (LET ((VAR '(A B C . #1=(1 2 3)))) (NCONC VAR '#1#))))</code><strong>	; </strong><em class="lineannotation"><span class="lineannotation">note shared structure!</span></em>
(my-func)
⇒ <code class="computeroutput">(A B C . #1=(1 2 3 . #1#))</code><strong>	; </strong><em class="lineannotation"><span class="lineannotation"><a class="" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/glo_c.html#circular_list">circular list</a>!</span></em>
(function-lambda-expression #'my-func )
⇒ <code class="computeroutput">(LAMBDA NIL (DECLARE (SYSTEM::IN-DEFUN MY-FUNC))
 (BLOCK MY-FUNC (LET ((VAR '(A B C . #1=(1 2 3 . #1#)))) (NCONC VAR '#1#))))</code><strong>	; </strong><em class="lineannotation"><span class="lineannotation">note circular value of var</span></em>
(my-func)<strong>	; </strong><em class="lineannotation"><span class="lineannotation">hangs because <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_nconc.html" target="_top"><code class="function">NCONC</code></a> cannot handle a circular argument</span></em></pre><p>Instead you must do
</p><pre class="programlisting">(defun my-func ()
  (let ((var (copy-list '(a b c))))
    (nconc var (copy-list '(1 2 3)))))</pre><p><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_disassemble.html" target="_top"><code class="function">DISASSEMBLE</code></a> will show the constants in your compiled functions
(see <a class="xref" href="#bytecode" title="Chapter 37. The CLISP bytecode specification">Chapter 37, <em>The <span class="command"><strong>CLISP</strong></span> bytecode specification</em></a> for the explanation of the <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_disassemble.html" target="_top"><code class="function">DISASSEMBLE</code></a>
output.)  As you see above, <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_function-_a-expression.html" target="_top"><code class="function">FUNCTION-LAMBDA-EXPRESSION</code></a> works for the
interpreted ones.</p><p>See <a class="ulink" href="http://norvig.com/luv-slides.ps" target="_top">Lisp Programming
  Style</a> for more useful information.</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-fp"></a><a id="faq-fp-q"></a><p><strong>A.4.10.</strong></p></td><td align="left" valign="top"><p>Why don't floating point arithmetic
   return what I want?</p><pre class="programlisting">
(- 1.1 0.9)
⇒ <code class="computeroutput">0.20000005</code>
</pre></td></tr><tr class="answer"><td align="left" valign="top"><p><strong>inexact</strong></p></td><td align="left" valign="top"><p>Floating point arithmetic is
  inherently <span class="emphasis"><em>inexact</em></span>, so this <span class="strong"><strong>not</strong></span> a bug,
  at least not a bug in <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>.
  You may argue that this is a bug in <a class="ulink" href="http://grouper.ieee.org/groups/754/" target="_top">IEEE 754</a>,
  but, before you do, please make sure that you do know
  <a class="ulink" href="http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html" target="_top">What
  Every Computer Scientist Should Know About Floating-Point Arithmetic</a>
  (or are at least familiar with the
  <a class="ulink" href="http://floating-point-gui.de/" target="_top">light version</a> thereof).
 </p><p>See also <a class="" href="https://sourceforge.net/p/clisp/mailman/clisp-list/">clisp-list</a>
  (<a class="gmane" href="http://article.gmane.org/gmane.lisp.clisp.general/9850"><code>Gmane/general/9850</code></a>/<a class="ulink" href="https://sourceforge.net/p/clisp/mailman/message/12275968/" target="_top">https://sourceforge.net/p/clisp/mailman/message/12275968/</a>/<a class="ulink" href="https://sourceforge.net/p/clisp/mailman/message/12275958/" target="_top">https://sourceforge.net/p/clisp/mailman/message/12275958/</a>).</p></td></tr><tr class="answer"><td align="left" valign="top"><p><strong>exact</strong></p></td><td align="left" valign="top"><p>If you want <span class="emphasis"><em>exact</em></span>
 calculations, use <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_rational.html" target="_top"><code class="classname">RATIONAL</code></a>s:</p><pre class="programlisting">
(- 11/10 9/10)
⇒ <code class="computeroutput">1/5</code></pre><p>
</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-random"></a><a id="faq-random-q"></a><p><strong>A.4.11.</strong></p></td><td align="left" valign="top"><p>Why does
   </p><pre class="screen"><strong><code class="prompt">$</code></strong> <span class="command"><strong><a href="clisp.html#clisp" class="olink">clisp</a></strong></span> <code class="option"><a href="clisp.html#opt-exec-expr" class="olink">-x</a></code> '(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_random.html" target="_top"><code class="function">RANDOM</code></a> 1s0)'</pre><p>
   always print the same number?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>Reproducibility is important.
  See <a class="xref" href="#random-state" title="12.2.7. Random-State Operations sec_12-1-7">Section 12.2.7, “Random-State Operations   sec_12-1-7”</a>.</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-pp-newline"></a><a id="faq-pp-newline-q"></a><p><strong>A.4.12.</strong></p></td><td align="left" valign="top"><p>Why is an extra line break
   inserted by the pretty printer?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>See <a class="xref" href="#ppr-first-newline" title="Variable CUSTOM:*PPRINT-FIRST-NEWLINE*">the section called “Variable <code class="varname">CUSTOM:*PPRINT-FIRST-NEWLINE*</code>”</a>.</p><p>For example, here you are pretty-printing two objects: a
  one-liner <span class="keysym">#\Q</span> and a two-liner <span class="keycode">CR</span>+<span class="keycode">LF</span>,
  and a line break is inserted between them so that they are printed on
  separate lines: </p><pre class="programlisting">
(defparameter crlf (coerce '(#\Return #\Linefeed) 'string))
⇒ <code class="computeroutput">CRLF</code>
(map 'list #'char-code (format nil "Q~a" crlf))
⇒ <code class="computeroutput">(81 10 13 10)</code><strong>	; </strong><em class="lineannotation"><span class="lineannotation">not (81 13 10) !</span></em>
</pre><p>When you want <span class="keycode">CR</span>+<span class="keycode">LF</span>-terminated lines, use <a class="link" href="#extfmt"><code class="constant">:EXTERNAL-FORMAT</code></a> <code class="constant">:DOS</code>
  argument when opening your <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/syscla_stream.html" target="_top"><code class="classname">STREAM</code></a>s.</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-warning"></a><a id="faq-warning-q"></a><p><strong>A.4.13.</strong></p></td><td align="left" valign="top"><p>How do I disable this annoying
   warning?</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p><a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> often issues <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_warning.html" target="_top"><code class="classname">WARNING</code></a>s when it encounters
  suspicious behavior.  It is best to fix your code rather than to
  suppress them.  To figure out where the warning is coming from, do
  <code class="code">(<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/spefor_setq.html" target="_top"><code class="function">SETQ</code></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/var_stbreak-on-signalsst.html" target="_top"><code class="varname">*BREAK-ON-SIGNALS*</code></a> '<a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/contyp_warning.html" target="_top"><code class="classname">WARNING</code></a>)</code> and examine
  the stack in the <a class="link" href="#debugger" title="25.2. Debugging Utilities sec_25-1-2">debugger</a> to see where the warning is coming from.</p><p>If everything else fails, read the
 <a class="link" href="#impnotes-top" title="Implementation Notes for GNU CLISP">manual</a>.</p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-scope"></a><a id="faq-scope-q"></a><p><strong>A.4.14.</strong></p></td><td align="left" valign="top"><p>Why does <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defparametercm_defvar.html" target="_top"><code class="function">DEFVAR</code></a> affect previously defined lexical closures?</p><pre class="programlisting">
(defun adder (val) (lambda (x) (+ x val)))
⇒ <code class="computeroutput">ADDER</code>
(setq add-10 (adder 10))
⇒ <code class="computeroutput">ADD-10</code>
(funcall add-10 32)
⇒ <code class="computeroutput">42</code><strong>	; </strong><em class="lineannotation"><span class="lineannotation">as expected</span></em>
(defvar val 12)
⇒ <code class="computeroutput">VAL</code>
(funcall add-10 0)
⇒ <code class="computeroutput">12</code><strong>	; </strong><em class="lineannotation"><span class="lineannotation">why not 10?!</span></em>
</pre></td></tr><tr class="answer"><td align="left" valign="top"><p><strong>Explanation</strong></p></td><td align="left" valign="top"><p>The above code does not conform to [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>], therefore <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a>
  can produce arbitrary results.
  See <a class="xref" href="#semantic-constraints" title="3.2.2.3. Semantic Constraints sec_3-2-2-3">Section 3.2.2.3, “Semantic Constraints   sec_3-2-2-3”</a>.</p></td></tr><tr class="answer"><td align="left" valign="top"><p><strong>Remedy</strong></p></td><td align="left" valign="top"><p>Always follow the naming convention for global special variables
  defined by <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defparametercm_defvar.html" target="_top"><code class="function">DEFVAR</code></a> and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defparametercm_defvar.html" target="_top"><code class="function">DEFPARAMETER</code></a> (e.g., <code class="varname">*FOO*</code>)
  and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/mac_defconstant.html" target="_top"><code class="function">DEFCONSTANT</code></a> (e.g., <code class="varname">+BAR+</code>).</p></td></tr><tr class="answer"><td align="left" valign="top"><p><strong>More</strong></p></td><td align="left" valign="top"><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="gmane" href="http://article.gmane.org/gmane.lisp.clisp.general/11945"><code>Gmane/general/11945</code></a>/<a class="ulink" href="https://sourceforge.net/p/clisp/mailman/message/13174197/" target="_top">https://sourceforge.net/p/clisp/mailman/message/13174197/</a></td></tr><tr><td><a class="gmane" href="http://article.gmane.org/gmane.lisp.clisp.general/11949"><code>Gmane/general/11949</code></a>/<a class="ulink" href="https://sourceforge.net/p/clisp/mailman/message/13174204/" target="_top">https://sourceforge.net/p/clisp/mailman/message/13174204/</a></td></tr></table></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-bad-error"></a><a id="faq-bad-error-q"></a><p><strong>A.4.15.</strong></p></td><td align="left" valign="top"><p>The error message is not helpful!</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>Sometimes an error message contains a compound object
  whose content you want to examine. Often this object will be available
  for <a class="link" href="#inspect" title="25.2.7. Function INSPECT"><code class="function">INSPECT</code></a>ion via the <span class="command"><strong>Inspect</strong></span> command (see
  <a class="xref" href="#debugger-deb-step-1" title="Table 25.3. Commands common to the debugger and the stepper">Table 25.3, “Commands common to the debugger and the stepper”</a>). E.g., </p><pre class="screen">
*** - READ: input stream #&lt;INPUT STRING-INPUT-STREAM&gt; ends within an object
The following restarts are available:
ABORT          :R1      ABORT
<strong><code class="prompt">Break 4 [1]&gt;</code></strong> <big><strong class="userinput"><code>:i</code></strong></big>
#&lt;SYSTEM::SIMPLE-END-OF-FILE #x000333CB82F8&gt;:  standard object
 type: SYSTEM::SIMPLE-END-OF-FILE
0 [$STREAM]:  #&lt;INPUT STRING-INPUT-STREAM&gt;
1 [$FORMAT-CONTROL]:
"~S: input stream ~S ends within an object
"
2 [$FORMAT-ARGUMENTS]:  (READ #&lt;INPUT STRING-INPUT-STREAM&gt;)
<strong><code class="prompt">INSPECT-- type :h for help; :q to return to the REPL ---&gt;</code></strong> <big><strong class="userinput"><code>0</code></strong></big>
#&lt;INPUT STRING-INPUT-STREAM&gt;:  atom
 type: STRING-STREAM
 class: #1=#&lt;BUILT-IN-CLASS STRING-STREAM&gt;
<strong><code class="prompt">INSPECT-- type :h for help; :q to return to the REPL ---&gt;</code></strong> <big><strong class="userinput"><code>:d</code></strong></big>

#&lt;INPUT STRING-INPUT-STREAM&gt; is an input-stream. It reads from "(foo" from 0 to 4 at 4.
</pre></td></tr><tr class="question"><td align="left" valign="top"><a id="faq-other-problem"></a><a id="faq-other-problem-q"></a><p><strong>A.4.16.</strong></p></td><td align="left" valign="top"><p>Why is the function <code class="function">FOO</code>
   broken?!</p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>When confronted with unexpected behavior,
  try looking in the <a class="xref" href="#impnotes-top" title="Implementation Notes for GNU CLISP"><span class="command"><strong>CLISP</strong></span> impnotes</a>.</p><p>E.g., <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_directory.html" target="_top"><code class="function">DIRECTORY</code></a> is different from the <a class="ulink" href="http://www.cons.org/cmucl/" target="_top"><span class="command"><strong>CMU CL</strong></span></a>
 implementation, so, to find out how to get the results you want,
 you should search the <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> implementation notes for "DIRECTORY".</p><p>Alternatively, since the implementation notes are organized in
 parallel to the [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>], and <a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/fun_directory.html" target="_top"><code class="function">DIRECTORY</code></a> belongs to the
 <a class="clhs" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/chap-20.html">Chapter 20</a> in [<span class="citation"><a class="link" href="#ansi-cl" title="ANSI INCITS 226-1994 (R1999) Information Technology - Programming Language - Common Lisp [formerly ANSI X3.226-1994 (R1999)]">ANSI CL standard</a></span>],
 you can just go to <a class="xref" href="#files" title="Chapter 20. Files chap-20">Chapter 20, <em>Files chap-20</em></a> in impnotes and look
 for "DIRECTORY" <a class="link" href="#directory" title="20.3.2. Function DIRECTORY">there</a>.
</p></td></tr></tbody></table></div></div><div class="appendix"><div class="titlepage"><div><div><h2 class="title"><a id="fdl"></a>Appendix B. GNU Free Documentation License</h2></div></div></div><p>Version 1.3, 3 November 2008</p><p>
    Copyright © 2000, 2001, 2002, 2007, 2008
    <a class="ulink" href="https://www.fsf.org/" target="_top">Free Software Foundation, Inc.</a>
  </p><p>
    Everyone is permitted to copy and distribute verbatim copies of this
    license document, but changing it is not allowed.
  </p><h3><a id="section0"></a>
    0. PREAMBLE
  </h3><p>
    The purpose of this License is to make a manual, textbook, or other
    functional and useful document “free” in the sense of freedom:
    to assure everyone the effective freedom to copy and redistribute it, with
    or without modifying it, either commercially or
    noncommercially. Secondarily, this License preserves for the author and
    publisher a way to get credit for their work, while not being considered
    responsible for modifications made by others.
  </p><p>
    This License is a kind of “copyleft”, which means that
    derivative works of the document must themselves be free in the same
    sense. It complements the GNU General Public License, which is a copyleft
    license designed for free software.
  </p><p>
    We have designed this License in order to use it for manuals for free
    software, because free software needs free documentation: a free program
    should come with manuals providing the same freedoms that the software
    does. But this License is not limited to software manuals; it can be used
    for any textual work, regardless of subject matter or whether it is
    published as a printed book. We recommend this License principally for
    works whose purpose is instruction or reference.
  </p><h3><a id="section1"></a>
    1. APPLICABILITY AND DEFINITIONS
  </h3><p>
    This License applies to any manual or other work, in any medium, that
    contains a notice placed by the copyright holder saying it can be
    distributed under the terms of this License. Such a notice grants a
    world-wide, royalty-free license, unlimited in duration, to use that work
    under the conditions stated herein. The “Document”, below,
    refers to any such manual or work. Any member of the public is a licensee,
    and is addressed as “you”. You accept the license if you copy,
    modify or distribute the work in a way requiring permission under
    copyright law.
  </p><p>
    A “Modified Version” of the Document means any work containing
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    A “Secondary Section” is a named appendix or a front-matter
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  </p><p>
    The “Invariant Sections” are certain Secondary Sections whose
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  </p><p>
    The “Cover Texts” are certain short passages of text that are
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  </p><p>
    A “Transparent” copy of the Document means a machine-readable
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  </p><p>
    Examples of suitable formats for Transparent copies include plain ASCII
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    some word processors for output purposes only.
  </p><p>
    The “Title Page” means, for a printed book, the title page
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    means the text near the most prominent appearance of the work’s
    title, preceding the beginning of the body of the text.
  </p><p>
    The “publisher” means any person or entity that distributes
    copies of the Document to the public.
  </p><p>
    A section “Entitled XYZ” means a named subunit of the Document
    whose title either is precisely XYZ or contains XYZ in parentheses
    following text that translates XYZ in another language. (Here XYZ stands
    for a specific section name mentioned below, such as
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    “Endorsements”, or “History”.) To “Preserve
    the Title” of such a section when you modify the Document means that
    it remains a section “Entitled XYZ” according to this
    definition.
  </p><p>
    The Document may include Warranty Disclaimers next to the notice which
    states that this License applies to the Document. These Warranty
    Disclaimers are considered to be included by reference in this License,
    but only as regards disclaiming warranties: any other implication that
    these Warranty Disclaimers may have is void and has no effect on the
    meaning of this License.
  </p><h3><a id="section2"></a>
    2. VERBATIM COPYING
  </h3><p>
    You may copy and distribute the Document in any medium, either
    commercially or noncommercially, provided that this License, the copyright
    notices, and the license notice saying this License applies to the
    Document are reproduced in all copies, and that you add no other
    conditions whatsoever to those of this License. You may not use technical
    measures to obstruct or control the reading or further copying of the
    copies you make or distribute. However, you may accept compensation in
    exchange for copies. If you distribute a large enough number of copies you
    must also follow the conditions in section 3.
  </p><p>
    You may also lend copies, under the same conditions stated above, and you
    may publicly display copies.
  </p><h3><a id="section3"></a>
    3. COPYING IN QUANTITY
  </h3><p>
    If you publish printed copies (or copies in media that commonly have
    printed covers) of the Document, numbering more than 100, and the
    Document’s license notice requires Cover Texts, you must enclose
    the copies in covers that carry, clearly and legibly, all these Cover
    Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on the
    back cover. Both covers must also clearly and legibly identify you as the
    publisher of these copies. The front cover must present the full title
    with all words of the title equally prominent and visible. You may add
    other material on the covers in addition. Copying with changes limited to
    the covers, as long as they preserve the title of the Document and satisfy
    these conditions, can be treated as verbatim copying in other respects.
  </p><p>
    If the required texts for either cover are too voluminous to fit legibly,
    you should put the first ones listed (as many as fit reasonably) on the
    actual cover, and continue the rest onto adjacent pages.
  </p><p>
    If you publish or distribute Opaque copies of the Document numbering more
    than 100, you must either include a machine-readable Transparent copy
    along with each Opaque copy, or state in or with each Opaque copy a
    computer-network location from which the general network-using public has
    access to download using public-standard network protocols a complete
    Transparent copy of the Document, free of added material. If you use the
    latter option, you must take reasonably prudent steps, when you begin
    distribution of Opaque copies in quantity, to ensure that this Transparent
    copy will remain thus accessible at the stated location until at least one
    year after the last time you distribute an Opaque copy (directly or
    through your agents or retailers) of that edition to the public.
  </p><p>
    It is requested, but not required, that you contact the authors of the
    Document well before redistributing any large number of copies, to give
    them a chance to provide you with an updated version of the Document.
  </p><h3><a id="section4"></a>
    4. MODIFICATIONS
  </h3><p>
    You may copy and distribute a Modified Version of the Document under the
    conditions of sections 2 and 3 above, provided that you release the
    Modified Version under precisely this License, with the Modified Version
    filling the role of the Document, thus licensing distribution and
    modification of the Modified Version to whoever possesses a copy of it. In
    addition, you must do these things in the Modified Version:
  </p><div class="orderedlist"><ol class="orderedlist" type="A"><li class="listitem">
        Use in the Title Page (and on the covers, if any) a title distinct
        from that of the Document, and from those of previous versions (which
        should, if there were any, be listed in the History section of the
        Document). You may use the same title as a previous version if the
        original publisher of that version gives permission.
      </li><li class="listitem">
        List on the Title Page, as authors, one or more persons or entities
        responsible for authorship of the modifications in the Modified
        Version, together with at least five of the principal authors of the
        Document (all of its principal authors, if it has fewer than five),
        unless they release you from this requirement.
      </li><li class="listitem">
        State on the Title page the name of the publisher of the Modified
        Version, as the publisher.
      </li><li class="listitem">
        Preserve all the copyright notices of the Document.
      </li><li class="listitem">
        Add an appropriate copyright notice for your modifications adjacent to
        the other copyright notices.
      </li><li class="listitem">
        Include, immediately after the copyright notices, a license notice
        giving the public permission to use the Modified Version under the
        terms of this License, in the form shown in the Addendum below.
      </li><li class="listitem">
        Preserve in that license notice the full lists of Invariant Sections
        and required Cover Texts given in the Document’s license
        notice.
      </li><li class="listitem">
        Include an unaltered copy of this License.
      </li><li class="listitem">
        Preserve the section Entitled “History”, Preserve its
        Title, and add to it an item stating at least the title, year, new
        authors, and publisher of the Modified Version as given on the Title
        Page. If there is no section Entitled “History” in the
        Document, create one stating the title, year, authors, and publisher
        of the Document as given on its Title Page, then add an item
        describing the Modified Version as stated in the previous sentence.
      </li><li class="listitem">
        Preserve the network location, if any, given in the Document for
        public access to a Transparent copy of the Document, and likewise the
        network locations given in the Document for previous versions it was
        based on.  These may be placed in the “History”
        section. You may omit a network location for a work that was published
        at least four years before the Document itself, or if the original
        publisher of the version it refers to gives permission.
      </li><li class="listitem">
        For any section Entitled “Acknowledgements” or
        “Dedications”, Preserve the Title of the section, and
        preserve in the section all the substance and tone of each of the
        contributor acknowledgements and/or dedications given therein.
      </li><li class="listitem">
        Preserve all the Invariant Sections of the Document, unaltered in
        their text and in their titles. Section numbers or the equivalent are
        not considered part of the section titles.
      </li><li class="listitem">
        Delete any section Entitled “Endorsements”. Such a section
        may not be included in the Modified Version.
      </li><li class="listitem">
        Do not retitle any existing section to be Entitled
        “Endorsements” or to conflict in title with any Invariant
        Section.
      </li><li class="listitem">
        Preserve any Warranty Disclaimers.
      </li></ol></div><p>
    If the Modified Version includes new front-matter sections or appendices
    that qualify as Secondary Sections and contain no material copied from the
    Document, you may at your option designate some or all of these sections
    as invariant. To do this, add their titles to the list of Invariant
    Sections in the Modified Version’s license notice. These titles
    must be distinct from any other section titles.
  </p><p>
    You may add a section Entitled “Endorsements”, provided it
    contains nothing but endorsements of your Modified Version by various
    parties — for example, statements of peer review or that the text
    has been approved by an organization as the authoritative definition of a
    standard.
  </p><p>
    You may add a passage of up to five words as a Front-Cover Text, and a
    passage of up to 25 words as a Back-Cover Text, to the end of the list of
    Cover Texts in the Modified Version. Only one passage of Front-Cover Text
    and one of Back-Cover Text may be added by (or through arrangements made
    by) any one entity. If the Document already includes a cover text for the
    same cover, previously added by you or by arrangement made by the same
    entity you are acting on behalf of, you may not add another; but you may
    replace the old one, on explicit permission from the previous publisher
    that added the old one.
  </p><p>
    The author(s) and publisher(s) of the Document do not by this License give
    permission to use their names for publicity for or to assert or imply
    endorsement of any Modified Version.
  </p><h3><a id="section5"></a>
    5. COMBINING DOCUMENTS
  </h3><p>
    You may combine the Document with other documents released under this
    License, under the terms defined in section 4 above for modified versions,
    provided that you include in the combination all of the Invariant Sections
    of all of the original documents, unmodified, and list them all as
    Invariant Sections of your combined work in its license notice, and that
    you preserve all their Warranty Disclaimers.
  </p><p>
    The combined work need only contain one copy of this License, and multiple
    identical Invariant Sections may be replaced with a single copy. If there
    are multiple Invariant Sections with the same name but different contents,
    make the title of each such section unique by adding at the end of it, in
    parentheses, the name of the original author or publisher of that section
    if known, or else a unique number. Make the same adjustment to the section
    titles in the list of Invariant Sections in the license notice of the
    combined work.
  </p><p>
    In the combination, you must combine any sections Entitled
    “History” in the various original documents, forming one
    section Entitled “History”; likewise combine any sections
    Entitled “Acknowledgements”, and any sections Entitled
    “Dedications”. You must delete all sections Entitled
    “Endorsements”.
  </p><h3><a id="section6"></a>
    6. COLLECTIONS OF DOCUMENTS
  </h3><p>
    You may make a collection consisting of the Document and other documents
    released under this License, and replace the individual copies of this
    License in the various documents with a single copy that is included in
    the collection, provided that you follow the rules of this License for
    verbatim copying of each of the documents in all other respects.
  </p><p>
    You may extract a single document from such a collection, and distribute
    it individually under this License, provided you insert a copy of this
    License into the extracted document, and follow this License in all other
    respects regarding verbatim copying of that document.
  </p><h3><a id="section7"></a>
    7. AGGREGATION WITH INDEPENDENT WORKS
  </h3><p>
    A compilation of the Document or its derivatives with other separate and
    independent documents or works, in or on a volume of a storage or
    distribution medium, is called an “aggregate” if the copyright
    resulting from the compilation is not used to limit the legal rights of
    the compilation’s users beyond what the individual works
    permit. When the Document is included in an aggregate, this License does
    not apply to the other works in the aggregate which are not themselves
    derivative works of the Document.
  </p><p>
    If the Cover Text requirement of section 3 is applicable to these copies
    of the Document, then if the Document is less than one half of the entire
    aggregate, the Document’s Cover Texts may be placed on covers that
    bracket the Document within the aggregate, or the electronic equivalent of
    covers if the Document is in electronic form. Otherwise they must appear
    on printed covers that bracket the whole aggregate.
  </p><h3><a id="section8"></a>
    8. TRANSLATION
  </h3><p>
    Translation is considered a kind of modification, so you may distribute
    translations of the Document under the terms of section 4. Replacing
    Invariant Sections with translations requires special permission from
    their copyright holders, but you may include translations of some or all
    Invariant Sections in addition to the original versions of these Invariant
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    license notices in the Document, and any Warranty Disclaimers, provided
    that you also include the original English version of this License and the
    original versions of those notices and disclaimers. In case of a
    disagreement between the translation and the original version of this
    License or a notice or disclaimer, the original version will prevail.
  </p><p>
    If a section in the Document is Entitled “Acknowledgements”,
    “Dedications”, or “History”, the requirement
    (section 4) to Preserve its Title (section 1) will typically require
    changing the actual title.
  </p><h3><a id="section9"></a>
    9. TERMINATION
  </h3><p>
    You may not copy, modify, sublicense, or distribute the Document except as
    expressly provided under this License. Any attempt otherwise to copy,
    modify, sublicense, or distribute it is void, and will automatically
    terminate your rights under this License.
  </p><p>
    However, if you cease all violation of this License, then your license
    from a particular copyright holder is reinstated (a) provisionally, unless
    and until the copyright holder explicitly and finally terminates your
    license, and (b) permanently, if the copyright holder fails to notify you
    of the violation by some reasonable means prior to 60 days after the
    cessation.
  </p><p>
    Moreover, your license from a particular copyright holder is reinstated
    permanently if the copyright holder notifies you of the violation by some
    reasonable means, this is the first time you have received notice of
    violation of this License (for any work) from that copyright holder, and
    you cure the violation prior to 30 days after your receipt of the notice.
  </p><p>
    Termination of your rights under this section does not terminate the
    licenses of parties who have received copies or rights from you under this
    License. If your rights have been terminated and not permanently
    reinstated, receipt of a copy of some or all of the same material does not
    give you any rights to use it.
  </p><h3><a id="section10"></a>
    10. FUTURE REVISIONS OF THIS LICENSE
  </h3><p>
    The Free Software Foundation may publish new, revised versions of the GNU
    Free Documentation License from time to time. Such new versions will be
    similar in spirit to the present version, but may differ in detail to
    address new problems or concerns. See
    <a class="ulink" href="https://www.gnu.org/licenses/" target="_top">https://www.gnu.org/licenses/</a>.
  </p><p>
    Each version of the License is given a distinguishing version number. If
    the Document specifies that a particular numbered version of this License
    “or any later version” applies to it, you have the option of
    following the terms and conditions either of that specified version or of
    any later version that has been published (not as a draft) by the Free
    Software Foundation. If the Document does not specify a version number of
    this License, you may choose any version ever published (not as a draft)
    by the Free Software Foundation. If the Document specifies that a proxy
    can decide which future versions of this License can be used, that
    proxy’s public statement of acceptance of a version permanently
    authorizes you to choose that version for the Document.
  </p><h3><a id="section11"></a>
    11. RELICENSING
  </h3><p>
    “Massive Multiauthor Collaboration Site” (or “MMC
    Site”) means any World Wide Web server that publishes copyrightable
    works and also provides prominent facilities for anybody to edit those
    works. A public wiki that anybody can edit is an example of such a
    server. A “Massive Multiauthor Collaboration” (or
    “MMC”) contained in the site means any set of copyrightable
    works thus published on the MMC site.
  </p><p>
    “CC-BY-SA” means the Creative Commons Attribution-Share Alike
    3.0 license published by Creative Commons Corporation, a not-for-profit
    corporation with a principal place of business in San Francisco,
    California, as well as future copyleft versions of that license published
    by that same organization.
  </p><p>
    “Incorporate” means to publish or republish a Document, in
    whole or in part, as part of another Document.
  </p><p>
    An MMC is “eligible for relicensing” if it is licensed under
    this License, and if all works that were first published under this
    License somewhere other than this MMC, and subsequently incorporated in
    whole or in part into the MMC, (1) had no cover texts or invariant
    sections, and (2) were thus incorporated prior to November 1, 2008.
  </p><p>
    The operator of an MMC Site may republish an MMC contained in the site
    under CC-BY-SA on the same site at any time before August 1, 2009,
    provided the MMC is eligible for relicensing.
  </p><h3><a id="addendum"></a>
    ADDENDUM: How to use this License for your documents
  </h3><p>
    To use this License in a document you have written, include a copy of the
    License in the document and put the following copyright and license
    notices just after the title page:
  </p><pre class="screen">Copyright © YEAR YOUR NAME

Permission is granted to copy, distribute and/or modify this document under the
terms of the GNU Free Documentation License, Version 1.3 or any later version
published by the Free Software Foundation; with no Invariant Sections, no
Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in
the section entitled “GNU Free Documentation License”.</pre><p>
    If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts,
    replace the “with… Texts.” line with this:
  </p><pre class="screen">with the Invariant Sections being LIST THEIR TITLES, with the Front-Cover Texts
being LIST, and with the Back-Cover Texts being LIST.</pre><p>
    If you have Invariant Sections without Cover Texts, or some other
    combination of the three, merge those two alternatives to suit the
    situation.
  </p><p>
    If your document contains nontrivial examples of program code, we
    recommend releasing these examples in parallel under your choice of free
    software license, such as the GNU General Public License, to permit their
    use in free software.
  </p></div><div class="appendix"><div class="titlepage"><div><div><h2 class="title"><a id="gpl"></a>Appendix C. GNU General Public License</h2></div><div><p class="releaseinfo">Version 2, June 1991</p></div><div><p class="copyright">Copyright © 1989, 1991 Free Software Foundation, Inc.</p></div><div><div class="legalnotice"><a id="gpl-legalnotice"></a><p>
        </p><div class="address"><p>Free Software Foundation, Inc.<br />
          <span class="street">51 Franklin Street, Fifth Floor</span>,<br />
          <span class="city">Boston</span>, <span class="state">MA</span> <span class="postcode">02110-1301</span><br />
          <span class="country">USA</span><br />
        </p></div><p>
      </p><p>Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.</p></div></div><div><p class="pubdate">Version 2, June 1991</p></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="#gpl-1">C.1. Preamble</a></span></dt><dt><span class="section"><a href="#gpl-2">C.2. TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION</a></span></dt><dd><dl><dt><span class="section"><a href="#gpl-2-0">C.2.1. Section 0</a></span></dt><dt><span class="section"><a href="#gpl-2-1">C.2.2. Section 1</a></span></dt><dt><span class="section"><a href="#gpl-2-2">C.2.3. Section 2</a></span></dt><dt><span class="section"><a href="#gpl-2-3">C.2.4. Section 3</a></span></dt><dt><span class="section"><a href="#gpl-2-4">C.2.5. Section 4</a></span></dt><dt><span class="section"><a href="#gpl-2-5">C.2.6. Section 5</a></span></dt><dt><span class="section"><a href="#gpl-2-6">C.2.7. Section 6</a></span></dt><dt><span class="section"><a href="#gpl-2-7">C.2.8. Section 7</a></span></dt><dt><span class="section"><a href="#gpl-2-8">C.2.9. Section 8</a></span></dt><dt><span class="section"><a href="#gpl-2-9">C.2.10. Section 9</a></span></dt><dt><span class="section"><a href="#gpl-2-10">C.2.11. Section 10</a></span></dt><dt><span class="section"><a href="#gpl-2-11">C.2.12. NO WARRANTY Section 11</a></span></dt><dt><span class="section"><a href="#gpl-2-12">C.2.13. Section 12</a></span></dt></dl></dd><dt><span class="section"><a href="#gpl-3">C.3. How to Apply These Terms to Your New Programs</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="gpl-1"></a>C.1. Preamble</h2></div></div></div><p>The licenses for most software are designed to take away your
      freedom to share and change it. By contrast, the GNU General Public License is
      intended to guarantee your freedom to share and change
      free software - to make sure the software is free for all its users.
      This General Public License applies to most of the Free Software
      Foundation's software and to any other program whose authors commit
      to using it. (Some other Free Software Foundation software is covered
      by the GNU Library General Public License instead.) You can apply it
      to your programs, too.</p><p>When we speak of free software, we are referring to freedom, not price.
      Our General Public Licenses are designed to make sure that you have the
      freedom to distribute copies of free software (and charge for this
      service if you wish), that you receive source code or can get it if you
      want it, that you can change the software or use pieces of it in new free
      programs; and that you know you can do these things.</p><p>To protect your rights, we need to make restrictions that forbid anyone
      to deny you these rights or to ask you to surrender the rights. These
      restrictions translate to certain responsibilities for you if you distribute
      copies of the software, or if you modify it.</p><p>For example, if you distribute copies of such a program, whether gratis or
      for a fee, you must give the recipients all the rights that you have. You
      must make sure that they, too, receive or can get the source code. And you
      must show them these terms so they know their rights.</p><p>We protect your rights with two steps:
      </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>copyright the software, and</p></li><li class="listitem"><p>offer you this license which gives you legal permission to copy,
            distribute and/or modify the software.</p></li></ol></div><p>
    </p><p>Also, for each author's protection and ours, we want to make certain that
      everyone understands that there is no warranty for this free software. If
      the software is modified by someone else and passed on, we want its
      recipients to know that what they have is not the original, so that any
      problems introduced by others will not reflect on the original authors'
      reputations.</p><p>Finally, any free program is threatened constantly by software patents.
      We wish to avoid the danger that redistributors of a free program will
      individually obtain patent licenses, in effect making the program
      proprietary. To prevent this, we have made it clear that any patent must be
      licensed for everyone's free use or not licensed at all.</p><p>The precise terms and conditions for copying, distribution and modification
      follow.</p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="gpl-2"></a>C.2. TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="section"><a href="#gpl-2-0">C.2.1. Section 0</a></span></dt><dt><span class="section"><a href="#gpl-2-1">C.2.2. Section 1</a></span></dt><dt><span class="section"><a href="#gpl-2-2">C.2.3. Section 2</a></span></dt><dt><span class="section"><a href="#gpl-2-3">C.2.4. Section 3</a></span></dt><dt><span class="section"><a href="#gpl-2-4">C.2.5. Section 4</a></span></dt><dt><span class="section"><a href="#gpl-2-5">C.2.6. Section 5</a></span></dt><dt><span class="section"><a href="#gpl-2-6">C.2.7. Section 6</a></span></dt><dt><span class="section"><a href="#gpl-2-7">C.2.8. Section 7</a></span></dt><dt><span class="section"><a href="#gpl-2-8">C.2.9. Section 8</a></span></dt><dt><span class="section"><a href="#gpl-2-9">C.2.10. Section 9</a></span></dt><dt><span class="section"><a href="#gpl-2-10">C.2.11. Section 10</a></span></dt><dt><span class="section"><a href="#gpl-2-11">C.2.12. NO WARRANTY Section 11</a></span></dt><dt><span class="section"><a href="#gpl-2-12">C.2.13. Section 12</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="gpl-2-0"></a>C.2.1. Section 0</h3></div></div></div><p>This License applies to any program or other work which contains a notice
        placed by the copyright holder saying it may be distributed under the terms
        of this General Public License. The <span class="quote">“<span class="quote">Program</span>”</span>, below, refers to any such
        program or work, and a
        <span class="quote">“<span class="quote">work based on the Program</span>”</span> means either
        the Program or any derivative work under copyright law: that is to say, a
        work containing the Program or a portion of it, either verbatim or with
        modifications and/or translated into another language. (Hereinafter, translation
        is included without limitation in the term
        <span class="quote">“<span class="quote">modification</span>”</span>.) Each licensee is addressed as <span class="quote">“<span class="quote">you</span>”</span>.</p><p>Activities other than copying, distribution and modification are not covered by
        this License; they are outside its scope. The act of running the Program is not
        restricted, and the output from the Program is covered only if its contents
        constitute a work based on the Program (independent of having been made by running
        the Program). Whether that is true depends on what the Program does.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="gpl-2-1"></a>C.2.2. Section 1</h3></div></div></div><p>You may copy and distribute verbatim copies of the Program's source code as you
        receive it, in any medium, provided that you conspicuously and appropriately
        publish on each copy an appropriate copyright notice and disclaimer of warranty;
        keep intact all the notices that refer to this License and to the absence of any
        warranty; and give any other recipients of the Program a copy of this License
        along with the Program.</p><p>You may charge a fee for the physical act of transferring a copy, and you may at
        your option offer warranty protection in exchange for a fee.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="gpl-2-2"></a>C.2.3. Section 2</h3></div></div></div><p>You may modify your copy or copies of the Program or any portion of it, thus
        forming a work based on the Program, and copy and distribute such modifications
        or work under the terms of
        <a class="link" href="#gpl-2-1" title="C.2.2. Section 1">Section 1</a> above, provided
        that you also meet all of these conditions:
        </p><div class="orderedlist"><ol class="orderedlist" type="a"><li class="listitem"><p>You must cause the modified files to carry prominent notices stating that
              you changed the files and the date of any change.</p></li><li class="listitem"><p>You must cause any work that you distribute or publish, that in whole or
              in part contains or is derived from the Program or any part thereof, to be
              licensed as a whole at no charge to all third parties under the terms of
              this License.</p></li><li class="listitem"><p>If the modified program normally reads commands interactively when run, you
              must cause it, when started running for such interactive use in the most
              ordinary way, to print or display an announcement including an appropriate
              copyright notice and a notice that there is no warranty (or else, saying
              that you provide a warranty) and that users may redistribute the program
              under these conditions, and telling the user how to view a copy of this
              License. (Exception: If the Program itself is interactive but does not
              normally print such an announcement, your work based on the Program is not
              required to print an   announcement.)</p></li></ol></div><p>
      </p><p>These requirements apply to the modified work as a whole. If identifiable sections
        of that work are not derived from the Program, and can be reasonably considered
        independent and separate works in themselves, then this License, and its terms,
        do not apply to those sections when you distribute them as separate works. But when
        you distribute the same sections as part of a whole which is a work based on the
        Program, the distribution of the whole must be on the terms of this License, whose
        permissions for other licensees extend to the entire whole, and thus to each and
        every part regardless of who wrote it.</p><p>Thus, it is not the intent of this section to claim rights or contest your rights
        to work written entirely by you; rather, the intent is to exercise the right to control
        the distribution of derivative or collective works based on the Program.</p><p>In addition, mere aggregation of another work not based on the Program with the Program
        (or with a work based on the Program) on a volume of a storage or distribution medium
        does not bring the other work under the scope of this License.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="gpl-2-3"></a>C.2.4. Section 3</h3></div></div></div><p>You may copy and distribute the Program (or a work based on it, under
        <a class="link" href="#gpl-2-2" title="C.2.3. Section 2">Section 2</a> in object code or executable form under the terms of
        <a class="link" href="#gpl-2-1" title="C.2.2. Section 1">Sections 1</a> and
        <a class="link" href="#gpl-2-2" title="C.2.3. Section 2">2</a> above provided that you also do one of the following:
        </p><div class="orderedlist"><ol class="orderedlist" type="a"><li class="listitem"><p>Accompany it with the complete corresponding machine-readable source code, which
              must be distributed under the terms of Sections 1 and 2 above on a medium
              customarily used for software interchange; or,</p></li><li class="listitem"><p>Accompany it with a written offer, valid for at least three years, to give any
              third party, for a charge no more than your cost of physically performing source
              distribution, a complete machine-readable copy of the corresponding source code,
              to be distributed under the terms of Sections 1 and 2 above on a medium customarily
              used for software interchange; or,</p></li><li class="listitem"><p>Accompany it with the information you received as to the offer to distribute
              corresponding source code. (This alternative is allowed only for noncommercial
              distribution and only if you received the program in object code or executable form
              with such an offer, in accord with Subsection b above.)</p></li></ol></div><p>
      </p><p>The source code for a work means the preferred form of the work for making modifications
        to it. For an executable work, complete source code means all the source code for all modules
        it contains, plus any associated interface definition files, plus the scripts used to control
        compilation and installation of the executable. However, as a special exception, the source
        code distributed need not include anything that is normally distributed (in either source or
        binary form) with the major components (compiler, kernel, and so on) of the operating system
        on which the executable runs, unless that component itself accompanies the executable.</p><p>If distribution of executable or object code is made by offering access to copy from a
        designated place, then offering equivalent access to copy the source code from the same place
        counts as distribution of the source code, even though third parties are not compelled to
        copy the source along with the object code.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="gpl-2-4"></a>C.2.5. Section 4</h3></div></div></div><p>You may not copy, modify, sublicense, or distribute the Program except as expressly provided
        under this License. Any attempt otherwise to copy, modify, sublicense or distribute the
        Program is void, and will automatically terminate your rights under this License. However,
        parties who have received copies, or rights, from you under this License will not have their
        licenses terminated so long as such parties remain in full compliance.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="gpl-2-5"></a>C.2.6. Section 5</h3></div></div></div><p>You are not required to accept this License, since you have not signed it. However, nothing
        else grants you permission to modify or distribute the Program or its derivative works.
        These actions are prohibited by law if you do not accept this License. Therefore, by modifying
        or distributing the Program (or any work based on the Program), you indicate your acceptance
        of this License to do so, and all its terms and conditions for copying, distributing or
        modifying the Program or works based on it.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="gpl-2-6"></a>C.2.7. Section 6</h3></div></div></div><p>Each time you redistribute the Program (or any work based on the Program), the recipient
        automatically receives a license from the original licensor to copy, distribute or modify
        the Program subject to these terms and conditions. You may not impose any further restrictions
        on the recipients' exercise of the rights granted herein. You are not responsible for enforcing
        compliance by third parties to this License.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="gpl-2-7"></a>C.2.8. Section 7</h3></div></div></div><p>If, as a consequence of a court judgment or allegation of patent infringement or for any other
        reason (not limited to patent issues), conditions are imposed on you (whether by court order,
        agreement or otherwise) that contradict the conditions of this License, they do not excuse you
        from the conditions of this License. If you cannot distribute so as to satisfy simultaneously
        your obligations under this License and any other pertinent obligations, then as a consequence
        you may not distribute the Program at all. For example, if a patent license would not permit
        royalty-free redistribution of the Program by all those who receive copies directly or
        indirectly through you, then the only way you could satisfy both it and this License would be
        to refrain entirely from distribution of the Program.</p><p>If any portion of this section is held invalid or unenforceable under any particular circumstance,
        the balance of the section is intended to apply and the section as a whole is intended to apply
        in other circumstances.</p><p>It is not the purpose of this section to induce you to infringe any patents or other property
        right claims or to contest validity of any such claims; this section has the sole purpose of
        protecting the integrity of the free software distribution system, which is implemented by public
        license practices. Many people have made generous contributions to the wide range of software
        distributed through that system in reliance on consistent application of that system; it is up
        to the author/donor to decide if he or she is willing to distribute software through any other
        system and a licensee cannot impose that choice.</p><p>This section is intended to make thoroughly clear what is believed to be a consequence of the
        rest of this License.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="gpl-2-8"></a>C.2.9. Section 8</h3></div></div></div><p>If the distribution and/or use of the Program is restricted in certain countries either by patents
        or by copyrighted interfaces, the original copyright holder who places the Program under this License
        may add an explicit geographical distribution limitation excluding those countries, so that
        distribution is permitted only in or among countries not thus excluded. In such case, this License
        incorporates the limitation as if written in the body of this License.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="gpl-2-9"></a>C.2.10. Section 9</h3></div></div></div><p>The Free Software Foundation may publish revised and/or new versions of the General Public License
        from time to time. Such new versions will be similar in spirit to the present version, but may differ
        in detail to address new problems or concerns.</p><p>Each version is given a distinguishing version number. If the Program specifies a version number of
        this License which applies to it and <span class="quote">“<span class="quote">any later version</span>”</span>, you have the option of following the terms
        and conditions either of that version or of any later version published by the Free Software
        Foundation. If the Program does not specify a version number of this License, you may choose any
        version ever published by the Free Software Foundation.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="gpl-2-10"></a>C.2.11. Section 10</h3></div></div></div><p>If you wish to incorporate parts of the Program into other free programs whose distribution
        conditions are different, write to the author to ask for permission. For software which is copyrighted
        by the Free Software Foundation, write to the Free Software Foundation; we sometimes make exceptions
        for this. Our decision will be guided by the two goals of preserving the free status of all
        derivatives of our free software and of promoting the sharing and reuse of software generally.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="gpl-2-11"></a>C.2.12. NO WARRANTY Section 11</h3></div></div></div><p>BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT
        PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR
        OTHER PARTIES PROVIDE THE PROGRAM <span class="quote">“<span class="quote">AS IS</span>”</span> WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED,
        INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
        PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE
        PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.</p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="gpl-2-12"></a>C.2.13. Section 12</h3></div></div></div><p>IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR
        ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU
        FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
        USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED
        INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH
        ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
        DAMAGES.</p><p>END OF TERMS AND CONDITIONS</p></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="gpl-3"></a>C.3. How to Apply These Terms to Your New Programs</h2></div></div></div><p>If you develop a new program, and you want it to be of the greatest
      possible use to the public, the best way to achieve this is to make it
      free software which everyone can redistribute and change under these terms.</p><p>To do so, attach the following notices to the program.  It is safest
      to attach them to the start of each source file to most effectively
      convey the exclusion of warranty; and each file should have at least
      the <span class="quote">“<span class="quote">copyright</span>”</span> line and a pointer to where the full notice is found.</p><p>&lt;one line to give the program's name and a brief idea of what it does.&gt;
      Copyright (C) &lt;year&gt;    &lt;name of author&gt;</p><p>This program is free software; you can redistribute it and/or modify
      it under the terms of the GNU General Public License as published by
      the Free Software Foundation; either version 2 of the License, or
      (at your option) any later version.</p><p>This program is distributed in the hope that it will be useful,
      but WITHOUT ANY WARRANTY; without even the implied warranty of
      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      GNU General Public License for more details.</p><p>You should have received a copy of the GNU General Public License
      along with this program; if not, write to the Free Software
      Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA</p><p>Also add information on how to contact you by electronic and paper mail.</p><p>If the program is interactive, make it output a short notice like this
      when it starts in an interactive mode:</p><p>Gnomovision version 69, Copyright (C) year name of author
      Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type <span class="quote">“<span class="quote">show w</span>”</span>.
      This is free software, and you are welcome to redistribute it
      under certain conditions; type <span class="quote">“<span class="quote">show c</span>”</span> for details.</p><p>The hypothetical commands <span class="quote">“<span class="quote">show w</span>”</span> and <span class="quote">“<span class="quote">show c</span>”</span> should
      show the appropriate parts of the General Public License.  Of course, the commands you
      use may be called something other than <span class="quote">“<span class="quote">show w</span>”</span> and <span class="quote">“<span class="quote">show c</span>”</span>;
      they could even be mouse-clicks or menu items--whatever suits your program.</p><p>You should also get your employer (if you work as a programmer) or your
      school, if any, to sign a <span class="quote">“<span class="quote">copyright disclaimer</span>”</span> for the program, if
      necessary.  Here is a sample; alter the names:</p><p>Yoyodyne, Inc., hereby disclaims all copyright interest in the program
      <span class="quote">“<span class="quote">Gnomovision</span>”</span> (which makes passes at compilers) written by James Hacker.</p><p>&lt;signature of Ty Coon&gt;, 1 April 1989
      Ty Coon, President of Vice</p><p>This General Public License does not permit incorporating your program into
      proprietary programs.  If your program is a subroutine library, you may
      consider it more useful to permit linking proprietary applications with the
      library.  If this is what you want to do, use the GNU Library General
      Public License instead of this License.</p></div></div></div><div class="index"><div class="titlepage"><div><div><h1 class="title"><a id="idx"></a>Index</h1></div></div></div><div xmlns:xlink="http://www.w3.org/1999/xlink" class="index"><div class="indexdiv"><h3>Symbols</h3><dl><dt id="ientry-idm278135370976">*COMPILE-WARNINGS*, <a class="indexterm" href="#compile-warn">Function COMPILE-FILE</a></dt><dt id="ientry-idm278135136368">*COMPILED-FILE-TYPES*, <a class="indexterm" href="#compiled-types">Function LOAD</a></dt><dt id="ientry-idm278117036176">*CURRENT-LANGUAGE*
 , <a class="indexterm" href="#curr-lang">The Language</a></dt><dt id="ientry-idm278134525840">*EDITOR*, <a class="indexterm" href="#editor">Function ED</a></dt><dt id="ientry-idm278137714112">*EQ-HASHFUNCTION*, <a class="indexterm" href="#eq-hashfunction">Function MAKE-HASH-TABLE</a></dt><dt id="ientry-idm278137704336">*EQL-HASHFUNCTION*, <a class="indexterm" href="#eql-hashfunction">Function MAKE-HASH-TABLE</a></dt><dt id="ientry-idm278137699328">*EQUAL-HASHFUNCTION*, <a class="indexterm" href="#equal-hashfunction">Function MAKE-HASH-TABLE</a></dt><dt id="ientry-idm278116444736">*FOREIGN-ENCODING*
 , <a class="indexterm" href="#foreign-enc">Default encodings</a></dt><dt id="ientry-idm278126274928">*FORWARD-REFERENCED-CLASS-MISDESIGN*, <a class="indexterm" href="#frc-bad">Inheritance Structure of Metaobject Classes</a></dt><dt id="ientry-idm278134555712">*INSPECT-LENGTH*, <a class="indexterm" href="#inspect-length">Function INSPECT</a></dt><dt id="ientry-idm278135147264">*LOAD-COMPILING*, <a class="indexterm" href="#load-comp">Function LOAD</a></dt><dt id="ientry-idm278135154192">*LOAD-ECHO*, <a class="indexterm" href="#load-echo">Function LOAD</a></dt><dt id="ientry-idm278135108032">*LOAD-OBSOLETE-ACTION*, <a class="indexterm" href="#load-obs">Function LOAD</a></dt><dt id="ientry-idm278116450144">*MISC-ENCODING*
 , <a class="indexterm" href="#misc-enc">Default encodings</a></dt><dt id="ientry-idm278116491520">*PATHNAME-ENCODING*
 , <a class="indexterm" href="#path-enc">Default encodings</a></dt><dt id="ientry-idm278135140112">*SOURCE-FILE-TYPES*, <a class="indexterm" href="#source-types">Function LOAD</a></dt><dt id="ientry-idm278116454512">*TERMINAL-ENCODING*
 , <a class="indexterm" href="#term-enc">Default encodings</a></dt><dt id="ientry-idm278137641680">*WARN-ON-HASHTABLE-NEEDING-REHASH-AFTER-GC*, <a class="indexterm" href="#hashtable-gc-rehash-warn">Interaction between HASH-TABLEs and garbage-collection</a></dt><dt id="ientry-idm278115529040">*WINDOW*
    , <a class="indexterm" href="#scr-win">Random Screen Access</a></dt></dl></div><div class="indexdiv"><h3>C</h3><dl><dt id="ientry-idm278114653360">callback, <a class="indexterm" href="#def-call-in-callback">Overview</a>, <a class="indexterm" href="#def-call-in-callback-main">Foreign functions</a></dt><dt id="ientry-idm278126219008">class</dt><dd><dl><dt>anonymous, <a class="indexterm" href="#class-anonymous">Initialization of Anonymous Classes</a></dt><dt>finalization, <a class="indexterm" href="#class-finalization">Class Finalization Protocol</a></dt><dt>interposed, <a class="indexterm" href="#class-interposed">Implementation and User Specialization</a></dt></dl></dd></dl></div><div class="indexdiv"><h3>D</h3><dl><dt id="ientry-idm278113779968">DEFAULT-FOREIGN-LANGUAGE
 , <a class="indexterm" href="#dflt-ffi-lang">The choice of the C flavor</a></dt><dt id="ientry-idm278117015728">DEFINTERNATIONAL
 , <a class="indexterm" href="#def-i-l">The Language</a></dt><dt id="ientry-idm278117024320">DEFLANGUAGE, <a class="indexterm" href="#deflang">The Language</a></dt><dt id="ientry-idm278117008720">DEFLOCALIZED, <a class="indexterm" href="#defloc">The Language</a></dt></dl></div><div class="indexdiv"><h3>E</h3><dl><dt id="ientry-idm278136613472">endianness, <a class="indexterm" href="#endianness-i">Binary input, READ-BYTE,   EXT:READ-INTEGER &amp; EXT:READ-FLOAT</a></dt></dl></div><div class="indexdiv"><h3>F</h3><dl><dt id="ientry-idm278141078384">final delimiter, <a class="indexterm" href="#fin-delim">Special Symbols   sec_1-4-1-3</a></dt><dt id="ientry-idm278114821456">foreign function, <a class="indexterm" href="#dffi-ff">Introduction</a></dt><dd><dl><dt>anonymous, <a class="indexterm" href="#dffi-ff-a">Foreign functions</a></dt><dt>call-in, <a class="indexterm" href="#dffi-ff-call-in">Foreign functions</a></dt><dt>call-out, <a class="indexterm" href="#dffi-ff-call-out">Foreign functions</a></dt><dt>named, <a class="indexterm" href="#dffi-ff-n">Foreign functions</a></dt></dl></dd><dt id="ientry-idm278113774624">foreign
    variable, <a class="indexterm" href="#dffi-fv">Foreign variables</a></dt><dt id="ientry-idm278135515040">FORMAT</dt><dd><dl><dt>~!, <a class="indexterm" href="#format-bang">Formatted Output   sec_22-3</a></dt><dt>~., <a class="indexterm" href="#format-dot">Formatted Output   sec_22-3</a></dt></dl></dd></dl></div><div class="indexdiv"><h3>G</h3><dl><dt id="ientry-idm278134353536">GC, <a class="indexterm" href="#gc-func">Function EXT:GC
   </a></dt><dt id="ientry-idm278140188560">GENERIC-FLET, <a class="indexterm" href="#gen-flet">Deviations from ANSI CL standard</a></dt><dt id="ientry-idm278140186512">GENERIC-LABELS, <a class="indexterm" href="#gen-labels">Deviations from ANSI CL standard</a></dt></dl></div><div class="indexdiv"><h3>L</h3><dl><dt id="ientry-idm278115429968">linking set, <a class="indexterm" href="#linkseti">Linking Set</a></dt><dt id="ientry-idm278117003264">LOCALIZED, <a class="indexterm" href="#localized">The Language</a></dt></dl></div><div class="indexdiv"><h3>M</h3><dl><dt id="ientry-idm278135835744">MAKE-BUFFERED-INPUT-STREAM, <a class="indexterm" href="#stream-buffer-i">Functions   EXT:MAKE-BUFFERED-INPUT-STREAM
    and   EXT:MAKE-BUFFERED-OUTPUT-STREAM
     </a></dt><dt id="ientry-idm278135833728">MAKE-BUFFERED-OUTPUT-STREAM, <a class="indexterm" href="#stream-buffer-o">Functions   EXT:MAKE-BUFFERED-INPUT-STREAM
    and   EXT:MAKE-BUFFERED-OUTPUT-STREAM
     </a></dt><dt id="ientry-idm278126530000">metaobject, <a class="indexterm" href="#mop-mo">Metaobjects</a></dt><dd><dl><dt>class, <a class="indexterm" href="#mop-class-mo">Classes</a></dt><dt>generic function, <a class="indexterm" href="#mop-gen-fun-mo">Generic Functions</a></dt><dt>implementation-specific, <a class="indexterm" href="#mo-impl">Implementation and User Specialization</a></dt><dt>method, <a class="indexterm" href="#mop-method-mo">Methods</a></dt><dt>method combination, <a class="indexterm" href="#mop-meth-comp-mo">Method Combinations</a></dt><dt>portable, <a class="indexterm" href="#mo-portable">Implementation and User Specialization</a></dt><dt>slot definition, <a class="indexterm" href="#mop-slot-def-mo">Slot Definitions</a></dt><dd><dl><dt>direct, <a class="indexterm" href="#mop-dsd-mo">Slot Definitions</a></dt><dt>effective, <a class="indexterm" href="#mop-esd-mo">Slot Definitions</a></dt></dl></dd><dt>specializer, <a class="indexterm" href="#spec-mo">Specializers</a></dt><dt>specified, <a class="indexterm" href="#mo-specified">Implementation and User Specialization</a></dt><dt>standard, <a class="indexterm" href="#std-mo">Inheritance Structure of Metaobject Classes</a></dt></dl></dd><dt id="ientry-idm278126540336">metaobject class, <a class="indexterm" href="#mo-cl">Metaobjects</a></dt><dd><dl><dt>basic, <a class="indexterm" href="#mop-ba-mo-cl">Metaobjects</a></dt></dl></dd><dt id="ientry-idm278126211808">method</dt><dd><dl><dt>effective, <a class="indexterm" href="#effective-method">Generic Function Invocation Protocol</a></dt><dt>extends, <a class="indexterm" href="#method-extends">Implementation and User Specialization</a></dt><dt>function, <a class="indexterm" href="#me-func">Generic Function Invocation Protocol</a>, <a class="indexterm" href="#method-lambda">Processing Method Bodies</a></dt><dt>overrides, <a class="indexterm" href="#method-overrides">Implementation and User Specialization</a></dt><dt>promoted, <a class="indexterm" href="#method-promoted">Implementation and User Specialization</a></dt><dt>specialized, <a class="indexterm" href="#method-specialized">Implementation and User Specialization</a></dt></dl></dd><dt id="ientry-idm278139856064">METHOD-CALL-ERROR, <a class="indexterm" href="#meth-call-err">Standard Method Combination   sec_7-6-6-2</a></dt><dt id="ientry-idm278139847696">METHOD-CALL-TYPE-ERROR, <a class="indexterm" href="#meth-call-type-err">Standard Method Combination   sec_7-6-6-2</a></dt><dt id="ientry-idm278115460528">module, <a class="indexterm" href="#module">Module Set</a></dt><dd><dl><dt>name, <a class="indexterm" href="#module-name">Module Set</a></dt></dl></dd><dt id="ientry-idm278115452432">module set, <a class="indexterm" href="#modseti">Module Set</a></dt></dl></div><div class="indexdiv"><h3>N</h3><dl><dt id="ientry-idm278139865536">NO-PRIMARY-METHOD, <a class="indexterm" href="#no-prim">Standard Method Combination   sec_7-6-6-2</a></dt></dl></div><div class="indexdiv"><h3>P</h3><dl><dt id="ientry-idm278139263024">PACKAGE</dt><dd><dl><dt>case-inverted, <a class="indexterm" href="#pack-case-inverted">Package Case-Sensitivity</a></dt><dt>case-sensitive, <a class="indexterm" href="#pack-case-sensitive">Package Case-Sensitivity</a></dt><dt>modern, <a class="indexterm" href="#pack-modern">Package Case-Sensitivity</a></dt></dl></dd><dt id="ientry-idm278139403936">PACKAGE-LOCK, <a class="indexterm" href="#pack-lock-f">Constraints on the “COMMON-LISP” Package   for Conforming Programs - package locking  sec_11-1-2-1-2</a></dt></dl></div><div class="indexdiv"><h3>R</h3><dl><dt id="ientry-idm278134367024">ROOM, <a class="indexterm" href="#room-func">Function ROOM</a></dt></dl></div><div class="indexdiv"><h3>S</h3><dl><dt id="ientry-idm278122970768">slot</dt><dd><dl><dt>directly
    accessible, <a class="indexterm" href="#slot-directly-accessible">Instance Structure Protocol</a></dt><dt>location, <a class="indexterm" href="#slot-location">Instance Structure Protocol</a></dt></dl></dd><dt id="ientry-idm278140838176">SYMBOL-MACRO-EXPAND, <a class="indexterm" href="#symbol-mex">Macro DEFINE-SYMBOL-MACRO</a></dt></dl></div><div class="indexdiv"><h3>T</h3><dl><dt id="ientry-idm278134539392">TIMES, <a class="indexterm" href="#times">Macro TIME</a></dt><dt id="ientry-idm278141037472">token</dt><dd><dl><dt>reserved, <a class="indexterm" href="#res-token">Symbols as Tokens   sec_2-3-4</a></dt></dl></dd><dt id="ientry-idm278113715296">trampoline, <a class="indexterm" href="#dffi-trampoline">Callbacks and memory management</a></dt></dl></div><div class="indexdiv"><h3>V</h3><dl><dt id="ientry-idm278139953504">visually similar, <a class="indexterm" href="#visually-similar">Variable CUSTOM:*SUPPRESS-SIMILAR-CONSTANT-REDEFINITION-WARNING*</a></dt></dl></div><div class="indexdiv"><h3>W</h3><dl><dt id="ientry-idm278112100608">WITH-OUTPUT-TO-PRINTER
 , <a class="indexterm" href="#with-print">Printing</a></dt><dt id="ientry-idm278139372224">WITHOUT-PACKAGE-LOCK, <a class="indexterm" href="#without-pack-lock">Constraints on the “COMMON-LISP” Package   for Conforming Programs - package locking  sec_11-1-2-1-2</a></dt></dl></div></div></div><div class="bibliography"><div class="titlepage"><div><div><h1 class="title"><a id="references"></a>References</h1></div></div></div><div class="bibliodiv"><h3 class="title"><a id="ref-books"></a>Books</h3><div class="biblioentry"><a id="CLtL1"></a><p>[<abbr class="abbrev">CLtL1</abbr>] <span class="authorgroup"><span class="firstname">Guy L.</span> <span class="surname">Steele</span>, <span class="lineage">Jr.</span>. </span><span class="title"><em>Common Lisp: the Language (1st Edition)</em>. </span><span class="pubdate">1984. </span><span class="pagenums">465 pages. </span>ISBN 0-932376-41-X. <span class="publisher"><span class="publishername">Digital Press. </span></span></p></div><div class="biblioentry"><a id="CLtL2"></a><p>[<abbr class="abbrev">CLtL2</abbr>] <span class="authorgroup"><span class="firstname">Guy L.</span> <span class="surname">Steele</span>, <span class="lineage">Jr.</span>. </span><span class="title"><em><a class="ulink" href="http://www.cs.cmu.edu/afs/cs.cmu.edu/project/ai-repository/ai/html/cltl/cltl2.html" target="_top">Common Lisp: the Language (2nd Edition)</a></em>. </span><span class="pubdate">1990. </span><span class="pagenums">1032 pages. </span>ISBN 1-555-58041-6. <span class="publisher"><span class="publishername">Digital Press. </span></span></p></div><div class="biblioentry"><a id="amop"></a><p>[<abbr class="abbrev">AMOP</abbr>] <span class="authorgroup"><span class="firstname">Gregor</span> <span class="surname">Kiczales</span>, <span class="firstname">Jim</span> <span class="surname">des Rivieres</span>, and <span class="firstname">Daniel G.</span> <span class="surname">Bobrow</span>. </span><span class="title"><em><a class="ulink" href="http://mop.lisp.se/" target="_top">The Art of the Metaobject
     Protocol</a></em>. </span><span class="pubdate">1991. </span><span class="pagenums">335 pages. </span>ISBN 0-262-61074-4. <span class="publisher"><span class="publishername"><a class="ulink" href="http://mitpress.mit.edu" target="_top">MIT
      Press</a>. </span></span></p></div></div><div class="bibliodiv"><h3 class="title"><a id="ref-ansi"></a>ANSI standard documents</h3><div class="biblioentry"><a id="ansi-cl"></a><p>[<abbr class="abbrev">ANSI CL</abbr>] ANSI CL standard<span class="pubdate">1994. </span><span class="title"><em><a class="ulink" href="http://webstore.ansi.org" target="_top">ANSI</a> INCITS 226-1994 (R1999)
    Information Technology - Programming Language - Common Lisp
    [formerly ANSI X3.226-1994 (R1999)]</em>. </span></p></div><div class="biblioentry"><a id="CLHS"></a><p>[<abbr class="abbrev">CLHS</abbr>] Common Lisp HyperSpec<span class="title"><em><a class="ulink" href="http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/FrontMatter/" target="_top">Common Lisp HyperSpec</a></em>. </span></p></div></div></div></div><div class="bookinfo"><hr /><table width="100%" summary="impnotes meta info"><th><td align="left">These notes document <a class="ulink" href="http://clisp.org" target="_top"><span class="command"><strong>CLISP</strong></span></a> version 2.49.60+</td><td align="right">Last modified: 2017-10-27</td></th></table></div><div class="custom-footer"><hr /><table width="100%"><tr><td align="left"><a href="http://clisp.org"><img src="clisp.png" width="48" height="48" alt="[CLISP home]" /></a></td><td align="center"><a href="https://sourceforge.net/p/clisp/donate/?source=impnotes-top"><img src="" width="88" height="32" alt="[Support CLISP]" /></a></td><td align="right"><a href="https://sourceforge.net/projects/clisp/"><img width="120" height="30" alt="[SourceForge]" src="" /></a></td></tr></table></div><hr /><form method="get" action="http://www.google.com/custom" target="_top"><table width="100%" border="0"><tr><td nowrap="nowrap" align="center"><input type="hidden" name="domains" value="clisp.org" /><label for="sbi" style="display: none">Enter your search terms</label><input type="text" name="q" size="50" maxlength="255" id="sbi" value="Implementation Notes for GNU CLISP" /><label for="sbb" style="display: none">Submit search form</label><input type="submit" name="sa" value="Google Search" id="sbb" /></td></tr><tr><td nowrap="nowrap" align="center"><input type="radio" name="sitesearch" value="" checked="1" id="ss0" /><label for="ss0" title="Search the Web"><small>Web</small></label><input type="radio" name="sitesearch" value="clisp.org" id="ss1" /><label for="ss1" title="Search clisp.org"><small>clisp.org</small></label><input type="hidden" name="client" value="pub-4445255502750357" /><input type="hidden" name="forid" value="1" /><input type="hidden" name="ie" value="UTF-8" /><input type="hidden" name="oe" value="UTF-8" /><input type="hidden" name="cof" value="GALT:#008000;GL:1;DIV:#336699;VLC:663399;AH:center;BGC:FFFFFF;LBGC:000000;ALC:0000FF;LC:0000FF;T:000000;GFNT:0000FF;GIMP:0000FF;LH:48;LW:48;L:http://clisp.cons.org/clisp.png;S:http://clisp.cons.org;FORID:1" /><input type="hidden" name="hl" value="en" /></td></tr></table></form><hr /></body></html>