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| 6 | <title>Boost.Python - <boost/python/pointee.hpp></title> |
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| 7 | |
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| 8 | <table border="0" cellpadding="7" cellspacing="0" width="100%" summary= |
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| 9 | "header"> |
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| 10 | <tr> |
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| 11 | <td valign="top" width="300"> |
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| 12 | <h3><a href="../../../../index.htm"><img height="86" width="277" alt= |
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| 13 | "C++ Boost" src="../../../../boost.png" border="0"></a></h3> |
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| 14 | |
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| 15 | <td valign="top"> |
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| 16 | <h1 align="center"><a href="../index.html">Boost.Python</a></h1> |
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| 17 | |
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| 18 | <h2 align="center">Header <boost/python/pointee.hpp></h2> |
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| 19 | </table> |
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| 20 | <hr> |
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| 21 | |
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| 22 | <h2>Contents</h2> |
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| 23 | |
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| 24 | <dl class="page-index"> |
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| 25 | <dt><a href="#introduction">Introduction</a> |
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| 26 | |
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| 27 | <dt><a href="#classes">Classes</a> |
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| 28 | |
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| 29 | <dd> |
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| 30 | <dl class="page-index"> |
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| 31 | <dt><a href="#pointee-spec">Class Template<code>pointee</code></a> |
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| 32 | |
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| 33 | <dd> |
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| 34 | <dl class="page-index"> |
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| 35 | <dt><a href="#pointee-spec-synopsis">Class Template |
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| 36 | <code>pointee</code> synopsis</a> |
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| 37 | </dl> |
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| 38 | </dl> |
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| 39 | |
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| 40 | <dt><a href="#examples">Example</a> |
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| 41 | </dl> |
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| 42 | <hr> |
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| 43 | |
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| 44 | <h2><a name="introduction"></a>Introduction</h2> |
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| 45 | |
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| 46 | <p><code><boost/python/pointee.hpp></code> introduces a |
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| 47 | traits <a |
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| 48 | href="../../../mpl/doc/refmanual/metafunction.html">metafunction</a> |
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| 49 | template <code>pointee<T></code> that can be used to extract the "pointed-to" type from the type of a pointer or smart pointer. |
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| 50 | |
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| 51 | <h2><a name="classes"></a>Classes</h2> |
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| 52 | |
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| 53 | <h3><a name="pointee-spec"></a>Class Template <code>pointee<class T></code></h3> |
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| 54 | |
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| 55 | <p><code>pointee<T></code> is used by the <code><a |
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| 56 | href="class.html#class_-spec">class_</a><...></code> |
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| 57 | template to deduce the type being held when a pointer or smart |
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| 58 | pointer type is used as its <code>HeldType</code> argument. |
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| 59 | |
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| 60 | <h4><a name="pointee-spec-synopsis"></a>Class Template |
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| 61 | <code>pointee</code> synopsis</h4> |
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| 62 | <pre> |
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| 63 | namespace boost { namespace python |
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| 64 | { |
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| 65 | template <class T> struct pointee |
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| 66 | { |
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| 67 | typedef T::element_type type; |
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| 68 | }; |
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| 69 | |
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| 70 | // specialization for pointers |
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| 71 | template <T> struct pointee<T*> |
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| 72 | { |
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| 73 | typedef T type; |
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| 74 | }; |
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| 75 | } |
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| 76 | </pre> |
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| 77 | |
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| 78 | |
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| 79 | <h2><a name="examples"></a>Example</h2> |
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| 80 | |
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| 81 | Given a 3rd-party smart pointer type |
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| 82 | <code>smart_pointer<T></code>, one might partially specialize |
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| 83 | <code>pointee<smart_pointer<T> ></code> so that it can be |
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| 84 | used as the <code>HeldType</code> for a class wrapper: |
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| 85 | |
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| 86 | <pre> |
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| 87 | #include <boost/python/pointee.hpp> |
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| 88 | #include <boost/python/class.hpp> |
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| 89 | #include <third_party_lib.hpp> |
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| 90 | |
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| 91 | namespace boost { namespace python |
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| 92 | { |
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| 93 | template <class T> struct pointee<smart_pointer<T> > |
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| 94 | { |
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| 95 | typedef T type; |
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| 96 | }; |
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| 97 | }} |
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| 98 | |
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| 99 | BOOST_PYTHON_MODULE(pointee_demo) |
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| 100 | { |
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| 101 | class_<third_party_class, smart_pointer<third_party_class> >("third_party_class") |
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| 102 | .def(...) |
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| 103 | ... |
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| 104 | ; |
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| 105 | } |
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| 106 | </pre> |
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| 107 | |
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| 108 | <p>Revised |
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| 109 | <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan --> |
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| 110 | 13 November, 2002 |
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| 111 | <!--webbot bot="Timestamp" endspan i-checksum="39359" --> |
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| 112 | |
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| 113 | |
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| 114 | <p><i>© Copyright <a href="../../../../people/dave_abrahams.htm">Dave |
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| 115 | Abrahams</a> 2002. </i> Distributed |
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| 116 | under the Boost Software License, Version 1.0. (See accompanying file |
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| 117 | LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)</p> |
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| 118 | |
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| 119 | |
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