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<html><head><title>XLISP class</title>
<link rel="stylesheet" type="text/css" href="reference.css">
</head>
<body>
<a href="../start.htm">Nyquist / XLISP 2.0</a> -
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<a href="../examples/examples.htm">Examples</a> |
<a href="reference-index.htm">Reference</a>
<hr>
<h1>class</h1>
<hr>
<p><table cellpadding="0" cellspacing="0" style="margin-left:10px"><tbody>
<tr valign="top">
<td><nobr>Type:</nobr></td>
<td><nobr> - </nobr></td>
<td width="100%"><nobr>object</nobr></td>
</tr>
<tr valign="top">
<td><nobr>Source:</nobr></td>
<td><nobr> - </nobr></td>
<td width="100%"><nobr>xlobj.c</nobr></td>
</tr>
</tbody></table></p>
<h2>Syntax</h2>
<dl>
<dt> class</dt>
</dl>
<h2>Description</h2>
<p>'class' is the built-in object class that is used to build other classes.
Classes are, essentially, the template for defining
<a href="object.htm">object</a> instances.</p>
<h2>Examples</h2>
<pre class="example">
(setq myclass (send class :new '(var))) <font color="#008844">; create MYCLASS with VAR</font>
(send myclass :answer :isnew '() <font color="#008844">; set up initialization</font>
'((setq var nil) self))
(send myclass :answer :set-it '(value) <font color="#008844">; create :SET-IT message</font>
'((setq var value)))
(setq my-obj (send myclass :new)) <font color="#008844">; create MY-OBJ of MYCLASS</font>
(send my-obj :set-it 5) <font color="#008844">; VAR is set to 5</font>
</pre>
<p><b>Class definition:</b> The internal definition of the 'class' object
instance looks like:</p>
<pre class="example">
Object is #<Object: #23fe2>, Class is #<Object: #23fe2>
MESSAGES = ((:ANSWER . #<Subr-: #23e48>)
(:ISNEW . #<Subr-: #23e84>)
(:NEW . #<Subr-: #23ea2>))
IVARS = (MESSAGES IVARS CVARS CVALS SUPERCLASS IVARCNT IVARTOTAL)
CVARS = NIL
CVALS = NIL
SUPERCLASS = #<Object: #23fd8>
IVARCNT = 7
IVARTOTAL = 7
#<Object: #23fe2>
</pre>
<p>The class of 'class' is 'class', itself. The superclass of 'class' is
<a href="object.htm">object</a>. Remember that the location
information [like #23fe2] varies from system to system, yours will probably
look different.</p>
<p><b>Built-in methods:</b> The built in methods in XLISP include:</p>
<ul>
<li><nobr><a href="keyword-answer.htm">:answer</a> - add a method to an <a href="object.htm">object</a></nobr></li>
<li><nobr><a href="keyword-class.htm">:class</a> - return the <a href="object.htm">object</a>'s class</nobr></li>
<li><nobr><a href="keyword-isnew.htm">:isnew</a> - run initialization code on <a href="object.htm">object</a></nobr></li>
<li><nobr><a href="keyword-new.htm">:new</a> - create a new <a href="object.htm">object</a> [instance or class]</nobr></li>
<li><nobr><a href="keyword-show.htm">:show</a> - show the internal state of the <a href="object.htm">object</a></nobr></li>
</ul>
<p><b>Message Structure:</b> The normal XLISP convention for a 'message' is
to have a valid symbol preceeded by a colon like
<a href="keyword-isnew.htm">:isnew</a> or ':my-message'. However, it
is possible to define a 'message' that is a symbol without a colon, but
this makes the code less readable.</p>
<p>See the
<a href="../manual/xlisp-man-010.htm#class">class</a>
object in the <nobr>XLISP 2.0</nobr> manual.</p>
<p><nobr> <a href="#top">Back to Top</nobr></a></p>
<hr>
<a href="../start.htm">Nyquist / XLISP 2.0</a> -
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