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<html><head><title>XLISP gensym</title>
<link rel="stylesheet" type="text/css" href="reference.css">
</head>
<body>
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<hr>
<h1>gensym</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>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>
<dl>
<dt>(gensym [<i>tag</i>])</dt>
<dd><i>tag</i> - an optional integer or string<br>
returns - the new symbol</dd>
</dl>
<h2>Description</h2>
<p>The 'gensym' function generates and returns a symbol. The default symbol
form is as a character 'G' followed by a number, 'Gn'. The default numbering
starts at '1'. You can change what the generated symbol looks like. By
calling 'gensym' with a string 'tag', the default string is set to the
string parameter. If 'tag' is an integer number, the current number is
set to the integer parameter.</p>
<h2>Examples</h2>
<pre class="example">
(gensym) <font color="#008844">; first time => G1</font>
(gensym 100) <font color="#008844">; returns G100</font>
(gensym "MYGENSYM") <font color="#008844">; returns MYGENSYM101</font>
(gensym 0) <font color="#008844">; returns MYGENSYM0</font>
(gensym) <font color="#008844">; returns MYGENSYM1</font>
(gensym "G") <font color="#008844">; \</font>
(gensym 0) <font color="#008844">; / put it back to 'normal'</font>
(gensym) <font color="#008844">; just like first time => G1</font>
</pre>
<p><b>Note:</b> It takes 2 calls to 'gensym' to set both portions of the
'gensym' symbol.</p>
<p><b>Note:</b> Although it is possible to call 'gensym' with numbers in the string
like "AB1", this does generate an odd sequence. What will happen is you will
get a sequence of symbols like:</p>
<pre class="example">
... AB18 AB19 AB110 AB111 ...
</pre>
<p>See the
<a href="../manual/xlisp-man-013.htm#gensym">gensym</a>
function in the <nobr>XLISP 2.0</nobr> manual.</p>
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