/Src/Dependencies/Boost/libs/python/doc/v2/ResultConverter.html

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  10. <title>Boost.Python - ResultConverter Concept</title>
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  16.     <td valign="top" width="300"> 
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  17.       <h3><a href="../../../../index.htm"><img height="86" width="277" alt="C++ Boost" src="../../../../boost.png" border="0"></a></h3>
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  19.     <td valign="top"> 
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  20.       <h1 align="center"><a href="../index.html">Boost.Python</a></h1>
    21. 

  21.       <h2 align="center">ResultConverter Concept</h2>
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  22.     </td>
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  23.   </tr>
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  24. </table>
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  25. <hr>
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  26. <dl class="page-index"> 
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  27.   <dt><a href="#introduction">Introduction</a></dt>
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  28.   <dt><a href="#concept-requirements">Concept Requirements</a></dt>
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  29.   <dd>
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  30.     <dl class="page-index"> 
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  31.       <dt><a href="#ResultConverter-concept">ResultConverter Concept</a></dt>
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  32.       <dt><a href="#ResultConverterGenerator-concept">ResultConverterGenerator Concept</a></dt>
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  33.     </dl>
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  34.   </dd>
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  35. </dl>
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  36. 

  37. <h2><a name="introduction"></a>Introduction</h2>
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  38. 

  39. <p>A ResultConverter for a type <code>T</code> is a type whose
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  40. instances can be used to convert C++ return values of type
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  41. <code>T</code> <code>to_python</code>. A ResultConverterGenerator is
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  42. an MPL unary metafunction class which, given the return type of a C++
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  43. function, returns a ResultConverter for that type. ResultConverters in
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  44. Boost.Python generally inspect library's registry of converters to
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  45. find a suitable converter, but converters which don't use the registry
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  46. are also possible.
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  47. 

  48. <h2><a name="concept-requirements"></a>Concept Requirements</h2>
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  49. <h3><a name="ResultConverter-concept"></a>ResultConverter Concept</h3>
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  50. 

  51. <p>In the table below, <code><b>C</b></code> denotes a ResultConverter
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  52. type for a type <b><code>R</code></b> , <code><b>c</b></code> denotes
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  53. an object of type <code><b>C</b></code> , and <code><b>r</b></code>
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  54. denotes an object of type <code><b>R</b></code>.
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  55. 

  56. <table summary="ResultConverter expressions" border="1" cellpadding="5">
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  57. 

  58.   <tr> 
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  59.     <td><b>Expression</b></td>
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  60.     <td><b>Type</b></td>
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  61.     <td><b>Semantics</b></td>
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  62.   </tr>
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  63. 

  64.   <tr> 
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  65.     <td valign="top"><code>C c;</code></td>
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  66.     <td>
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  67.     <td>Constructs a <code>C</code> object.
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  68.   </tr>
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  69. 

  70.   <tr> 
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  71.     <td valign="top"><code>c.convertible()</code></td>
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  72.     <td>convertible to <code>bool</code></td>
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  73.     <td><code>false</code> iff no conversion from any <code>R</code> value
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  74.     to a Python object is possible.</td>
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  75.   </tr>
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  76. 

  77.   <tr> 
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  78.     <td valign="top"><code>c(r)</code></td>
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  79.     <td>convertible to <code>PyObject*</code></td>
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  80.     <td>A pointer to a Python object corresponding to <code>r</code>,
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  81.     or <code>0</code> iff <code>r</code> could not be converted
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  82.     <code>to_python</code>, in which case <a
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  83.     href="http://www.python.org/doc/current/api/exceptionHandling.html#l2h-71">PyErr_Occurred</a>
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  84.     should return non-zero.</td>
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  85.   </tr>
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  86.   <tr> 
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  87.     <td valign="top"><code>c.get_pytype()</code></td>
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  88.     <td><code>PyTypeObject const*</code></td>
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  89.     <td>A pointer to a Python Type object corresponding to result of the conversion,
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  90.     or <code>0</code>. Used for documentation generation. If <code>0</code> is returned
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  91.     the generated type in the documentation will be <b>object</b> .</td>
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  92.   </tr>
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  93. </table>
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  94. 

  95. <h3><a name="ResultConverterGenerator-concept"></a>ResultConverterGenerator Concept</h3>
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  96. <p>In the table below, <code><b>G</b></code> denotes a
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  97. ResultConverterGenerator type and <code><b>R</b></code> denotes a possible
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  98. C++ function return type.
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  99. 

  100. <table summary="ResultConverterGenerator expressions" border="1" cellpadding="5">
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  101.   <tr> 
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  102.     <td><b>Expression</b></td>
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  103.     <td><b>Requirements</b></td>
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  104.   </tr>
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  105.   <tr> 
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  106.     <td valign="top"><code>G::apply&lt;R&gt;::type</code></td>
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  107.     <td>A ResultConverter type for <code>R</code>.</td>
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  108. </table>
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  109. 

  110. <hr>
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  111. <p>Revised 
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  112.   <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan -->
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  113.   09 May, 2002    <!--Luann's birthday! -->
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  114.   <!--webbot bot="Timestamp" endspan i-checksum="39359" -->
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  115. </p>
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  116.     <p><i>&copy; Copyright <a href="http://www.boost.org/people/dave_abrahams.htm">Dave
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  117.     Abrahams</a> 2002. </i>
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  118. 

  119. <p>Permission to copy, use, modify, sell
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  120.  and distribute this software is granted provided this copyright notice appears
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  121.  in all copies. This software is provided "as is" without express or implied
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  122.  warranty, and with no claim as to its suitability for any purpose.
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