<?xml version="1.0" encoding="ascii"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <title>genshi.template.eval.Undefined</title> <link rel="stylesheet" href="epydoc.css" type="text/css" /> <script type="text/javascript" src="epydoc.js"></script> </head> <body bgcolor="white" text="black" link="blue" vlink="#204080" alink="#204080"> <!-- ==================== NAVIGATION BAR ==================== --> <table class="navbar" border="0" width="100%" cellpadding="0" bgcolor="#a0c0ff" cellspacing="0"> <tr valign="middle"> <!-- Home link --> <th> <a href="genshi-module.html">Home</a> </th> <!-- Tree link --> <th> <a href="module-tree.html">Trees</a> </th> <!-- Index link --> <th> <a href="identifier-index.html">Indices</a> </th> <!-- Help link --> <th> <a href="help.html">Help</a> </th> <!-- Project homepage --> <th class="navbar" align="right" width="100%"> <table border="0" cellpadding="0" cellspacing="0"> <tr><th class="navbar" align="center" ><a class="navbar" target="_top" href="../index.html">Documentation Index</a></th> </tr></table></th> </tr> </table> <table width="100%" cellpadding="0" cellspacing="0"> <tr valign="top"> <td width="100%"> <span class="breadcrumbs"> <a href="genshi-module.html">Package genshi</a> :: <a href="genshi.template-module.html">Package template</a> :: <a href="genshi.template.eval-module.html">Module eval</a> :: Class Undefined </span> </td> <td> <table cellpadding="0" cellspacing="0"> <!-- hide/show private --> </table> </td> </tr> </table> <!-- ==================== CLASS DESCRIPTION ==================== --> <h1 class="epydoc">Class Undefined</h1><p class="nomargin-top"></p> <pre class="base-tree"> object --+ | <strong class="uidshort">Undefined</strong> </pre> <hr /> <p>Represents a reference to an undefined variable.</p> <p>Unlike the Python runtime, template expressions can refer to an undefined variable without causing a <code class="link">NameError</code> to be raised. The result will be an instance of the <a href="genshi.template.eval.Undefined-class.html" class="link">Undefined</a> class, which is treated the same as <tt class="rst-docutils literal">False</tt> in conditions, but raise an exception on any other operation:</p> <pre class="py-doctest"> <span class="py-prompt">>>> </span>foo = Undefined(<span class="py-string">'foo'</span>) <span class="py-prompt">>>> </span>bool(foo) <span class="py-output">False</span> <span class="py-output"></span><span class="py-prompt">>>> </span>list(foo) <span class="py-output">[]</span> <span class="py-output"></span><span class="py-prompt">>>> </span><span class="py-keyword">print</span>(foo) <span class="py-output">undefined</span></pre> <p>However, calling an undefined variable, or trying to access an attribute of that variable, will raise an exception that includes the name used to reference that undefined variable.</p> <pre class="py-doctest"> <span class="py-prompt">>>> </span>try: <span class="py-more">... </span> foo(<span class="py-string">'bar'</span>) <span class="py-more">... </span><span class="py-keyword">except</span> UndefinedError, e: <span class="py-more">... </span> <span class="py-keyword">print</span> e.msg <span class="py-output">"foo" not defined</span></pre> <pre class="py-doctest"> <span class="py-prompt">>>> </span>try: <span class="py-more">... </span> foo.bar <span class="py-more">... </span><span class="py-keyword">except</span> UndefinedError, e: <span class="py-more">... </span> <span class="py-keyword">print</span> e.msg <span class="py-output">"foo" not defined</span></pre> <hr /> <div class="fields"> <p><strong>See Also:</strong> <a href="genshi.template.eval.LenientLookup-class.html" class="link">LenientLookup</a> </p> </div><!-- ==================== INSTANCE METHODS ==================== --> <a name="section-InstanceMethods"></a> <table class="summary" border="1" cellpadding="3" cellspacing="0" width="100%" bgcolor="white"> <tr bgcolor="#70b0f0" class="table-header"> <td align="left" colspan="2" class="table-header"> <span class="table-header">Instance Methods</span></td> </tr> <tr> <td width="15%" align="right" valign="top" class="summary"> <span class="summary-type"> </span> </td><td class="summary"> <table width="100%" cellpadding="0" cellspacing="0" border="0"> <tr> <td><span class="summary-sig"><a href="genshi.template.eval.Undefined-class.html#__init__" class="summary-sig-name">__init__</a>(<span class="summary-sig-arg">self</span>, <span class="summary-sig-arg">name</span>, <span class="summary-sig-arg">owner</span>=<span class="summary-sig-default">UNDEFINED</span>)</span><br /> Initialize the object.</td> <td align="right" valign="top"> </td> </tr> </table> </td> </tr> <tr> <td width="15%" align="right" valign="top" class="summary"> <span class="summary-type"> </span> </td><td class="summary"> <table width="100%" cellpadding="0" cellspacing="0" border="0"> <tr> <td><span class="summary-sig"><a name="__iter__"></a><span class="summary-sig-name">__iter__</span>(<span class="summary-sig-arg">self</span>)</span></td> <td align="right" valign="top"> </td> </tr> </table> </td> </tr> <tr> <td width="15%" align="right" valign="top" class="summary"> <span class="summary-type"> </span> </td><td class="summary"> <table width="100%" cellpadding="0" cellspacing="0" border="0"> <tr> <td><span class="summary-sig"><a name="__nonzero__"></a><span class="summary-sig-name">__nonzero__</span>(<span class="summary-sig-arg">self</span>)</span></td> <td align="right" valign="top"> </td> </tr> </table> </td> </tr> <tr> <td width="15%" align="right" valign="top" class="summary"> <span class="summary-type"> </span> </td><td class="summary"> <table width="100%" cellpadding="0" cellspacing="0" border="0"> <tr> <td><span class="summary-sig"><a href="genshi.template.eval.Undefined-class.html#__repr__" class="summary-sig-name">__repr__</a>(<span class="summary-sig-arg">self</span>)</span><br /> repr(x)</td> <td align="right" valign="top"> </td> </tr> </table> </td> </tr> <tr> <td width="15%" align="right" valign="top" class="summary"> <span class="summary-type"> </span> </td><td class="summary"> <table width="100%" cellpadding="0" cellspacing="0" border="0"> <tr> <td><span class="summary-sig"><a href="genshi.template.eval.Undefined-class.html#__str__" class="summary-sig-name">__str__</a>(<span class="summary-sig-arg">self</span>)</span><br /> str(x)</td> <td align="right" valign="top"> </td> </tr> </table> </td> </tr> <tr> <td width="15%" align="right" valign="top" class="summary"> <span class="summary-type"> </span> </td><td class="summary"> <table width="100%" cellpadding="0" cellspacing="0" border="0"> <tr> <td><span class="summary-sig"><a name="__getitem__"></a><span class="summary-sig-name">__getitem__</span>(<span class="summary-sig-arg">self</span>, <span class="summary-sig-arg">*args</span>, <span class="summary-sig-arg">**kwargs</span>)</span><br /> Raise an <a href="genshi.template.eval.UndefinedError-class.html" class="link">UndefinedError</a>.</td> <td align="right" valign="top"> </td> </tr> </table> </td> </tr> <tr> <td width="15%" align="right" valign="top" class="summary"> <span class="summary-type"> </span> </td><td class="summary"> <table width="100%" cellpadding="0" cellspacing="0" border="0"> <tr> <td><span class="summary-sig"><a name="__getattr__"></a><span class="summary-sig-name">__getattr__</span>(<span class="summary-sig-arg">self</span>, <span class="summary-sig-arg">*args</span>, <span class="summary-sig-arg">**kwargs</span>)</span><br /> Raise an <a href="genshi.template.eval.UndefinedError-class.html" class="link">UndefinedError</a>.</td> <td align="right" valign="top"> </td> </tr> </table> </td> </tr> <tr> <td width="15%" align="right" valign="top" class="summary"> <span class="summary-type"> </span> </td><td class="summary"> <table width="100%" cellpadding="0" cellspacing="0" border="0"> <tr> <td><span class="summary-sig"><a name="__call__"></a><span class="summary-sig-name">__call__</span>(<span class="summary-sig-arg">self</span>, <span class="summary-sig-arg">*args</span>, <span class="summary-sig-arg">**kwargs</span>)</span><br /> Raise an <a href="genshi.template.eval.UndefinedError-class.html" class="link">UndefinedError</a>.</td> <td align="right" valign="top"> </td> </tr> </table> </td> </tr> <tr> <td colspan="2" class="summary"> <p class="indent-wrapped-lines"><b>Inherited from <code>object</code></b>: <code>__delattr__</code>, <code>__format__</code>, <code>__getattribute__</code>, <code>__hash__</code>, <code>__new__</code>, <code>__reduce__</code>, <code>__reduce_ex__</code>, <code>__setattr__</code>, <code>__sizeof__</code>, <code>__subclasshook__</code> </p> </td> </tr> </table> <!-- ==================== CLASS VARIABLES ==================== --> <a name="section-ClassVariables"></a> <table class="summary" border="1" cellpadding="3" cellspacing="0" width="100%" bgcolor="white"> <tr bgcolor="#70b0f0" class="table-header"> <td align="left" colspan="2" class="table-header"> <span class="table-header">Class Variables</span></td> </tr> <tr> <td width="15%" align="right" valign="top" class="summary"> <span class="summary-type"> </span> </td><td class="summary"> <a name="__length_hint__"></a><span class="summary-name">__length_hint__</span> = <code title="None">None</code><br /> hash(x) </td> </tr> </table> <!-- ==================== PROPERTIES ==================== --> <a name="section-Properties"></a> <table class="summary" border="1" cellpadding="3" cellspacing="0" width="100%" bgcolor="white"> <tr bgcolor="#70b0f0" class="table-header"> <td align="left" colspan="2" class="table-header"> <span class="table-header">Properties</span></td> </tr> <tr> <td colspan="2" class="summary"> <p class="indent-wrapped-lines"><b>Inherited from <code>object</code></b>: <code>__class__</code> </p> </td> </tr> </table> <!-- ==================== METHOD DETAILS ==================== --> <a name="section-MethodDetails"></a> <table class="details" border="1" cellpadding="3" cellspacing="0" width="100%" bgcolor="white"> <tr bgcolor="#70b0f0" class="table-header"> <td align="left" colspan="2" class="table-header"> <span class="table-header">Method Details</span></td> </tr> </table> <a name="__init__"></a> <div> <table class="details" border="1" cellpadding="3" cellspacing="0" width="100%" bgcolor="white"> <tr><td> <table width="100%" cellpadding="0" cellspacing="0" border="0"> <tr valign="top"><td> <h3 class="epydoc"><span class="sig"><span class="sig-name">__init__</span>(<span class="sig-arg">self</span>, <span class="sig-arg">name</span>, <span class="sig-arg">owner</span>=<span class="sig-default">UNDEFINED</span>)</span> <br /><em class="fname">(Constructor)</em> </h3> </td><td align="right" valign="top" > </td> </tr></table> Initialize the object. <dl class="fields"> <dt>Parameters:</dt> <dd><ul class="nomargin-top"> <li><strong class="pname"><code>name</code></strong> - the name of the reference</li> <li><strong class="pname"><code>owner</code></strong> - the owning object, if the variable is accessed as a member</li> </ul></dd> <dt>Overrides: object.__init__ </dt> </dl> </td></tr></table> </div> <a name="__repr__"></a> <div> <table class="details" border="1" cellpadding="3" cellspacing="0" width="100%" bgcolor="white"> <tr><td> <table width="100%" cellpadding="0" cellspacing="0" border="0"> <tr valign="top"><td> <h3 class="epydoc"><span class="sig"><span class="sig-name">__repr__</span>(<span class="sig-arg">self</span>)</span> <br /><em class="fname">(Representation operator)</em> </h3> </td><td align="right" valign="top" > </td> </tr></table> repr(x) <dl class="fields"> <dt>Overrides: object.__repr__ <dd><em class="note">(inherited documentation)</em></dd> </dt> </dl> </td></tr></table> </div> <a name="__str__"></a> <div> <table class="details" border="1" cellpadding="3" cellspacing="0" width="100%" bgcolor="white"> <tr><td> <table width="100%" cellpadding="0" cellspacing="0" border="0"> <tr valign="top"><td> <h3 class="epydoc"><span class="sig"><span class="sig-name">__str__</span>(<span class="sig-arg">self</span>)</span> <br /><em class="fname">(Informal representation operator)</em> </h3> </td><td align="right" valign="top" > </td> </tr></table> str(x) <dl class="fields"> <dt>Overrides: object.__str__ <dd><em class="note">(inherited documentation)</em></dd> </dt> </dl> </td></tr></table> </div> <br /> <!-- ==================== NAVIGATION BAR ==================== --> <table class="navbar" border="0" width="100%" cellpadding="0" bgcolor="#a0c0ff" cellspacing="0"> <tr valign="middle"> <!-- Home link --> <th> <a href="genshi-module.html">Home</a> </th> <!-- Tree link --> <th> <a href="module-tree.html">Trees</a> </th> <!-- Index link --> <th> <a href="identifier-index.html">Indices</a> </th> <!-- Help link --> <th> <a href="help.html">Help</a> </th> <!-- Project homepage --> <th 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