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136 lines
3.9 KiB
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<link rel="stylesheet" type="text/css" href="../boost.css">
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<title>Boost.Python - <boost/python/copy_const_reference.hpp></title>
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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=
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"C++ Boost" src="../../../../c++boost.gif" border="0"></a></h3>
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<td valign="top">
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<h1 align="center">Boost.Python</h1>
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<h2 align="center">Header
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<boost/python/copy_const_reference.hpp></h2>
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</table>
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<hr>
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<h2>Contents</h2>
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<dl class="page-index">
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<dt><a href="#classes">Classes</a>
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<dd>
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<dl class="page-index">
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<dt><a href="#copy_const_reference-spec">Class
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<code>copy_const_reference</code></a>
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<dd>
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<dl class="page-index">
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<dt><a href="#copy_const_reference-spec-synopsis">Class
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<code>copy_const_reference</code> synopsis</a>
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<dt><a href="#copy_const_reference-spec-metafunctions">Class
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<code>copy_const_reference</code> metafunctions</a>
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</dl>
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</dl>
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<dt><a href="#examples">Example</a>
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</dl>
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<hr>
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<h2><a name="classes"></a>Classes</h2>
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<h3><a name="copy_const_reference-spec"></a>Class
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<code>copy_const_reference</code></h3>
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<p><code>copy_const_reference</code> is a model of <a href=
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"ResultConverter.html#ResultConverterGenerator-concept">ResultConverterGenerator</a> which can be
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used to wrap C++ functions returning a reference-to-const type such that
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the referenced value is copied into a new Python object.
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<h4><a name="copy_const_reference-spec-synopsis"></a>Class
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<code>copy_const_reference</code> synopsis</h4>
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<pre>
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namespace boost { namespace python
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{
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struct copy_const_reference
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{
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template <class T> struct apply;
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};
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}}
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</pre>
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<h4><a name="copy_const_reference-spec-metafunctions"></a>Class
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<code>copy_const_reference</code> metafunctions</h4>
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<pre>
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template <class T> struct apply
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</pre>
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<dl class="metafunction-semantics">
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<dt><b>Requires:</b> <code>T</code> is <code>U const&</code> for some
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<code>U</code>.
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<dt><b>Returns:</b> <code>typedef <a href=
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"to_python_value.html#to_python_value-spec">to_python_value</a><T>
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type;</code>
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</dl>
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<h2><a name="examples"></a>Example</h2>
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<h3>C++ Module Definition</h3>
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<pre>
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#include <boost/python/module.hpp>
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#include <boost/python/class.hpp>
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#include <boost/python/copy_const_reference.hpp>
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#include <boost/python/return_value_policy.hpp>
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// classes to wrap
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struct Bar { int x; }
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struct Foo {
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Foo(int x) : { b.x = x; }
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Bar const& get_bar() const { return b; }
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private:
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Bar b;
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};
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// Wrapper code
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using namespace boost::python;
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BOOST_PYTHON_MODULE_INIT(my_module)
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{
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module m("my_module")
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.add(
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class_<Bar>()
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)
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.add(
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class_<Foo>()
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.def_init(args<int>())
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.def("get_bar", &Foo::get_bar
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, return_value_policy<copy_const_reference>())
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)
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;
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}
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</pre>
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<h3>Python Code</h3>
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<pre>
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>>> from my_module import *
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>>> f = Foo(3) # create a Foo object
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>>> b = f.get_bar() # make a copy of the internal Bar object
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</pre>
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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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15 February, 2002
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<!--webbot bot="Timestamp" endspan i-checksum="39359" -->
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<p><i>© Copyright <a href="../../../../people/dave_abrahams.htm">Dave
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Abrahams</a> 2002. All Rights Reserved.</i>
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