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<html><head><title>XLISP :isnew</title>
<link rel="stylesheet" type="text/css" href="reference.css">
</head>
<body>
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<a href="../examples/examples.htm">Examples</a> |
<a href="reference-index.htm">Reference</a>
<hr>
<h1>:isa</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>message selector</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>
<p><div class="box">
<dl>
<dt>(<a href="send.htm">send</a> <i>object</i> :isa <i>class</i>) - test if object inherits from class</dt>
<dd>returns - <a href="../reference/t.htm"> T </a> if object
is an instance of class or a subclass of class, otherwise
<a href="../reference/nil.htm">NIL</a><br><br></dd>
</dl>
</div></p>
<h2>Description</h2>
<p>The ':isa' message selector tests if an object inherits from a class.</p>
<h2>Examples</h2>
<pre class="example">
(setq a-class (send class :new '(state))) <font color="#008844">; create a new class A-CLASS with STATE</font>
(send a-class :answer :isnew '() <font color="#008844">; set up initialization</font>
'((setq state nil) self))
(send a-class :answer :set-it '(value) <font color="#008844">; create :SET-IT message</font>
'((setq state value)))
(setq an-obj (send a-class :new)) <font color="#008844">; create AN-OBJ out of A-CLASS</font>
(send an-obj :show) <font color="#008844">; returns object - STATE = NIL</font>
(send an-obj :set-it 5) <font color="#008844">; STATE is set to 5</font>
(send an-obj :show) <font color="#008844">; returns object - STATE = 5</font>
(SEND an-obj :ISNEW) <font color="#008844">; re-initialize AN-OBJ</font>
(send an-obj :show) <font color="#008844">; returns object - STATE = NIL</font>
</pre>
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