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    <title>Boost.Python -
    &lt;boost/python/return_value_policy.hpp&gt;</title>
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          <h2 align="center">Header
          &lt;boost/python/return_value_policy.hpp&gt;</h2>
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    <h2>Contents</h2>

    <dl class="page-index">
      <dt><a href="#introduction">Introduction</a></dt>

      <dt><a href="#classes">Classes</a></dt>

      <dd>
        <dl class="page-index">
          <dt><a href="#return_value_policy-spec">Class Template
          <code>return_value_policy</code></a></dt>

          <dd>
            <dl class="page-index">
              <dt><a href="#return_value_policy-spec-synopsis">Class Template
              <code>return_value_policy</code> synopsis</a></dt>
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      <dt><a href="#examples">Example</a></dt>
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    <h2><a name="introduction"></a>Introduction</h2>
    <code>return_value_policy</code> instantiations are simply models of <a
    href="CallPolicies.html">CallPolicies</a> which are composed of a <a
    href=
    "ResultConverter.html#ResultConverterGenerator-concept">ResultConverterGenerator</a>
    and optional <code>Base</code> <a href=
    "CallPolicies.html">CallPolicies</a>. 

    <h2><a name="classes"></a>Classes</h2>

    <h3><a name="return_value_policy-spec"></a>Class template
    <code>return_value_policy</code></h3>

    <table border="1" summary="return_value_policy template parameters">
      <caption>
        <b><code>return_value_policy</code> template parameters</b>
      </caption>

      <tr>
        <th>Parameter</th>

        <th>Requirements</th>

        <th>Default</th>
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      <tr>
        <td><a href=
        "ResultConverter.html#ResultConverterGenerator-concept">ResultConverterGenerator</a></td>

        <td>A model of <a href=
        "ResultConverter.html#ResultConverterGenerator-concept">ResultConverterGenerator</a>.</td>
      </tr>

      <tr>
        <td><code>Base</code></td>

        <td>A model of <a href="CallPolicies.html">CallPolicies</a></td>

        <td><code><a href=
        "default_call_policies.html#default_call_policies-spec">default_call_policies</a></code></td>
      </tr>
    </table>

    <h4><a name="return_value_policy-spec-synopsis"></a>Class template
    <code>return_value_policy</code> synopsis</h4>
<pre>
namespace boost { namespace python
{
  template &lt;class ResultConverterGenerator, class Base = default_call_policies&gt;
  struct return_value_policy : Base
  {
      typedef ResultConverterGenerator result_converter;
  };
}}
</pre>

    <h2><a name="examples"></a>Example</h2>

    <h3>C++ Module Definition</h3>
<pre>
#include &lt;boost/python/module.hpp&gt;
#include &lt;boost/python/class.hpp&gt;
#include &lt;boost/python/copy_const_reference.hpp&gt;
#include &lt;boost/python/return_value_policy.hpp&gt;

// classes to wrap
struct Bar { int x; }

struct Foo {
   Foo(int x) : { b.x = x; }
   Bar const&amp; get_bar() const { return b; }
 private:
   Bar b;
};

// Wrapper code
using namespace boost::python;
BOOST_PYTHON_MODULE(my_module)
{
   class_&lt;Bar&gt;("Bar");

   class_&lt;Foo&gt;("Foo", init&lt;int&gt;())
      .def("get_bar", &amp;Foo::get_bar
          , return_value_policy&lt;copy_const_reference&gt;())
      ;
}
</pre>

    <h3>Python Code</h3>
<pre>
&gt;&gt;&gt; from my_module import *
&gt;&gt;&gt; f = Foo(3)         # create a Foo object
&gt;&gt;&gt; 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>&copy; Copyright <a href=
    "http://www.boost.org/people/dave_abrahams.htm">Dave Abrahams</a> 2002.</i></p>
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