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97 lines
3.3 KiB
HTML
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97 lines
3.3 KiB
HTML
Executable File
<!-- Copyright David Abrahams 2006. Distributed under the Boost -->
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<!-- Software License, Version 1.0. (See accompanying -->
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<!-- file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) -->
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
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<link rel="stylesheet" type="text/css" href=../../../../boost.css>
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<title>Boost.Python - Extractor Concept</title>
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</head>
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<body link="#0000ff" vlink="#800080">
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<table border="0" cellpadding="7" cellspacing="0" width="100%" summary=
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"header">
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<tr>
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<td valign="top" width="300">
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<h3><a href="../../../../index.htm"><img height="86" width="277" alt="C++ Boost" src="../../../../boost.png" border="0"></a></h3>
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</td>
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<td valign="top">
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<h1 align="center"><a href="../index.html">Boost.Python</a></h1>
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<h2 align="center">Extractor Concept</h2>
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</td>
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</tr>
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</table>
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<hr>
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<dl class="page-index">
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<dt><a href="#introduction">Introduction</a></dt>
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<dt><a href="#concept-requirements">Concept Requirements</a></dt>
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<dl class="page-index">
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<dt><a href="#Extractor-concept">Extractor Concept</a></dt>
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</dl>
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<dt><a href="#notes">Notes</a></dt>
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</dl>
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<h2><a name="introduction"></a>Introduction</h2>
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<p>An Extractor is a class which Boost.Python can use to extract C++
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objects from Python objects, and is typically used by facilities that
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define <code>from_python</code> conversions for
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"traditional" Python extension types.
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<h2><a name="concept-requirements"></a>Concept Requirements</h2>
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<h3><a name="Extractor-concept"></a>Extractor Concept</h3>
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<p>In the table below, <code><b>X</b></code> denotes a model of
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Extractor and <code><b>a</b></code> denotes an instance of a Python
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object type.
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<table summary="Extractor expressions" border="1" cellpadding="5">
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<tr>
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<td><b>Expression</b></td>
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<td><b>Type</b></td>
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<td><b>Semantics</b></td>
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</tr>
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<tr>
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<td valign="top"><code>X::execute(a)</code></td>
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<td>non-void
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<td>Returns the C++ object being extracted. The
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<code>execute</code> function must not be overloaded.
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</tr>
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<tr>
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<td valign="top"><code>&a.ob_type</code>
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<td><code><a
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href="http://www.python.org/doc/2.2/ext/dnt-type-methods.html">PyTypeObject</a>**</code>
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<td>Points to the <code>ob_type</code> field of an object which is
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layout-compatible with <code>PyObject</code>
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</tr>
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</tr>
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</table>
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<h2><a name="notes"></a>Notes</h2>
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Informally, an Extractor's <code>execute</code> member must be a
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non-overloaded static function whose single argument is a Python
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object type. Acceptable Python object types include those publicly (and
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unambiguously) derived from <code>PyObject</code>, and POD types which
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are layout-compatible with PyObject.
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<hr>
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<p>Revised
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<!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan -->
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13 November, 2002
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<!--webbot bot="Timestamp" endspan i-checksum="39359" -->
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</p>
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<p><i>© Copyright <a href="../../../../people/dave_abrahams.htm">Dave
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Abrahams</a> 2002. </i>
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<p>Permission to copy, use, modify, sell
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and distribute this software is granted provided this copyright notice appears
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in all copies. This software is provided "as is" without express or implied
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warranty, and with no claim as to its suitability for any purpose.
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</body>
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</html>
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