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<h1 align="center"><a href="../index.html">Boost.Python</a></h1>
<h2 align="center">Header
<boost/python/return_by_value.hpp></h2>
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<h2>Contents</h2>
<dl class="page-index">
<dt><a href="#classes">Classes</a></dt>
<dd>
<dl class="page-index">
<dt><a href="#return_by_value-spec">Class
<code>return_by_value</code></a></dt>
<dd>
<dl class="page-index">
<dt><a href="#return_by_value-spec-synopsis">Class
<code>return_by_value</code> synopsis</a></dt>
<dt><a href="#return_by_value-spec-metafunctions">Class
<code>return_by_value</code> metafunctions</a></dt>
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</dd>
</dl>
</dd>
<dt><a href="#examples">Example</a></dt>
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<hr>
<h2><a name="classes"></a>Classes</h2>
<h3><a name="return_by_value-spec"></a>Class
<code>return_by_value</code></h3>
<p><code>return_by_value</code> is a model of <a href=
"ResultConverter.html#ResultConverterGenerator-concept">ResultConverterGenerator</a>
which can be used to wrap C++ functions returning any reference or value
type such that the return value is copied into a new Python object.</p>
<h4><a name="return_by_value-spec-synopsis"></a>Class
<code>return_by_value</code> synopsis</h4>
<pre>
namespace boost { namespace python
{
struct return_by_value
{
template <class T> struct apply;
};
}}
</pre>
<h4><a name="return_by_value-spec-metafunctions"></a>Class
<code>return_by_value</code> metafunctions</h4>
<pre>
template <class T> struct apply
</pre>
<dl class="metafunction-semantics">
<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/return_by_value.hpp>
#include <boost/python/return_value_policy.hpp>
// classes to wrap
struct Bar { };
Bar global_bar;
// functions to wrap:
Bar b1();
Bar& b2();
Bar const& b3();
// Wrapper code
using namespace boost::python;
template <class R>
void def_void_function(char const* name, R (*f)())
{
def(name, f, return_value_policy<return_by_value>());
}
BOOST_PYTHON_MODULE(my_module)
{
class_<Bar>("Bar");
def_void_function("b1", b1);
def_void_function("b2", b2);
def_void_function("b3", b3);
}
</pre>
<h3>Python Code</h3>
<pre>
>>> from my_module import *
>>> b = b1() # each of these calls
>>> b = b2() # creates a brand
>>> b = b3() # new 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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