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<html><head><title>XLISP boundp</title>
<link rel="stylesheet" type="text/css" href="reference.css">
</head>
<body>
<a href="../start.htm">Nyquist / XLISP 2.0</a> -
<a href="../manual/contents.htm">Contents</a> |
<a href="../tutorials/tutorials.htm">Tutorials</a> |
<a href="../examples/examples.htm">Examples</a> |
<a href="reference-index.htm">Reference</a>
<hr>
<h1>boundp</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>predicate function (subr)</nobr></td>
</tr>
<tr valign="top">
<td><nobr>Source:</nobr></td>
<td><nobr> - </nobr></td>
<td width="100%"><nobr>xlbfun.c</nobr></td>
</tr>
</tbody></table></p>
<h2>Syntax</h2>
<p><div class="box">
<dl>
<dt>(<b>boundp</b> <i>symbol</i>)</dt>
<dd><i>symbol</i> - a symbol expression<br>
returns - <a href="t.htm"> T </a> if a value is
bound to the symbol, <a href="nil.htm">NIL</a> otherwise</dd>
</dl>
</div></p>
<h2>Description</h2>
<p>The 'boundp' predicate function tests if 'symbol' evaluates to a symbol
in <nobr>the <a href="global-obarray.htm">*obarray*</a></nobr> with a value
bound to it. <nobr><a href="t.htm"> T </a> is</nobr> returned if
'symbol' has a value, <a href="nil.htm">NIL</a> is returned otherwise. Note
that 'boundp' does not test if local <a href="let.htm">let</a> variables, or
class or instance variables exist.</p>
<h2>Examples</h2>
<pre class="example">
(setq a 1) => 1 <font color="#008844">; create a variable A in the *OBARRAY*</font>
(boundp 'a) => T <font color="#008844">; variable A has a value 1</font>
(let ((b 'value))
(boundp b)) => NIL <font color="#008844">; BOUNDP does NOT test LET bindings</font>
(defun foo (x) <font color="#008844">; create a function FOO in the *OBARRAY*</font>
(print x)) => FOO
(boundp 'foo) => NIL <font color="#008844">; FOO is not a variable</font>
(print myvar) => <font color="#AA0000">error: unbound variable - MYVAR</font>
(boundp 'myvar) => NIL
(setq myvar 'abc) <font color="#008844">; give MYVAR a value</font>
(boundp 'myvar) => T
</pre>
<p>Note that 'symbol' is a symbol expression. This means that 'symbol' is
evaluated and the return value is tested:</p>
<pre class="example">
(setq myvar 'qq) <font color="#008844">; MYVAR evaluates to QQ</font>
(boundp myvar) => NIL <font color="#008844">; but QQ has no value yet</font>
(setq qq 'new-value) <font color="#008844">; give QQ a value</font>
(boundp myvar) => T
</pre>
<p>See also:</p>
<ul>
<li><nobr>Contents → <a href="../manual/contents.htm#predicate-functions">Predicate Functions</a></nobr></li>
</ul>
<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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