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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<!-- Copyright David Abrahams 2006. Distributed under the Boost -->
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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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<td valign="top" width="300">
<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 valign="top">
<h1 align="center"><a href="../index.html">Boost.Python</a></h1>
<h2 align="center">Header
<boost/python/copy_const_reference.hpp></h2>
</td>
</tr>
</table>
<hr>
<h2>Contents</h2>
<dl class="page-index">
<dt><a href="#classes">Classes</a></dt>
<dd>
<dl class="page-index">
<dt><a href="#copy_const_reference-spec">Class
<code>copy_const_reference</code></a></dt>
<dd>
<dl class="page-index">
<dt><a href="#copy_const_reference-spec-synopsis">Class
<code>copy_const_reference</code> synopsis</a></dt>
<dt><a href="#copy_const_reference-spec-metafunctions">Class
<code>copy_const_reference</code> metafunctions</a></dt>
</dl>
</dd>
</dl>
</dd>
<dt><a href="#examples">Example</a></dt>
</dl>
<hr>
<h2><a name="classes"></a>Classes</h2>
<h3><a name="copy_const_reference-spec"></a>Class
<code>copy_const_reference</code></h3>
<p><code>copy_const_reference</code> is a model of <a href=
"ResultConverter.html#ResultConverterGenerator-concept">ResultConverterGenerator</a>
which can be used to wrap C++ functions returning a reference-to-const
type such that the referenced value is copied into a new Python
object.</p>
<h4><a name="copy_const_reference-spec-synopsis"></a>Class
<code>copy_const_reference</code> synopsis</h4>
<pre>
namespace boost { namespace python
{
struct copy_const_reference
{
template <class T> struct apply;
};
}}
</pre>
<h4><a name="copy_const_reference-spec-metafunctions"></a>Class
<code>copy_const_reference</code> metafunctions</h4>
<pre>
template <class T> struct apply
</pre>
<dl class="metafunction-semantics">
<dt><b>Requires:</b> <code>T</code> is <code>U const&</code> for
some <code>U</code>.</dt>
<dt><b>Returns:</b> <code>typedef <a href=
"to_python_value.html#to_python_value-spec">to_python_value</a><T>
type;</code></dt>
</dl>
<h2><a name="examples"></a>Example</h2>
<h3>C++ Module Definition</h3>
<pre>
#include <boost/python/module.hpp>
#include <boost/python/class.hpp>
#include <boost/python/copy_const_reference.hpp>
#include <boost/python/return_value_policy.hpp>
// classes to wrap
struct Bar { int x; }
struct Foo {
Foo(int x) : { b.x = x; }
Bar const& get_bar() const { return b; }
private:
Bar b;
};
// Wrapper code
using namespace boost::python;
BOOST_PYTHON_MODULE(my_module)
{
class_<Bar>("Bar");
class_<Foo>("Foo", init<int>())
.def("get_bar", &Foo::get_bar
, return_value_policy<copy_const_reference>())
;
}
</pre>
<h3>Python Code</h3>
<pre>
>>> from my_module import *
>>> f = Foo(3) # create a Foo object
>>> b = f.get_bar() # make a copy of the internal Bar object
</pre>
<p>Revised
<!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan -->
13 November, 2002
<!--webbot bot="Timestamp" endspan i-checksum="39359" -->
</p>
<p><i>© Copyright <a href=
"http://www.boost.org/people/dave_abrahams.htm">Dave Abrahams</a> 2002.</i></p>
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