boost_1_45_0/libs/python/doc/v2/return_by_value.html - nest-learning-thermostat/5.0/boost - Git at Google

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           <h1 align="center"><a href="../index.html">Boost.Python</a></h1>

           <h2 align="center">Header
           &lt;boost/python/return_by_value.hpp&gt;</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>
             </dl>
           </dd>
         </dl>
       </dd>

       <dt><a href="#examples">Example</a></dt>
     </dl>
     <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 &lt;class T&gt; struct apply;
     };
 }}
 </pre>

     <h4><a name="return_by_value-spec-metafunctions"></a>Class
     <code>return_by_value</code> metafunctions</h4>
 <pre>
 template &lt;class T&gt; 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>&lt;T&gt;
       type;</code></dt>
     </dl>

     <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/return_by_value.hpp&gt;
 #include &lt;boost/python/return_value_policy.hpp&gt;

 // classes to wrap
 struct Bar { };

 Bar global_bar;

 // functions to wrap:
 Bar b1();
 Bar&amp; b2();
 Bar const&amp; b3();

 // Wrapper code
 using namespace boost::python;
 template &lt;class R&gt;
 void def_void_function(char const* name, R (*f)())
 {
    def(name, f, return_value_policy&lt;return_by_value&gt;());
 }

 BOOST_PYTHON_MODULE(my_module)
 {
     class_&lt;Bar&gt;("Bar");
     def_void_function("b1", b1);
     def_void_function("b2", b2);
     def_void_function("b3", b3);
 }
 </pre>

     <h3>Python Code</h3>
 <pre>
 &gt;&gt;&gt; from my_module import *
 &gt;&gt;&gt; b = b1() # each of these calls
 &gt;&gt;&gt; b = b2() # creates a brand
 &gt;&gt;&gt; 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>&copy; Copyright <a href=
     "http://www.boost.org/people/dave_abrahams.htm">Dave Abrahams</a> 2002.</i></p>
   </body>
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	<!-- Copyright David Abrahams 2006. Distributed under the Boost -->
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	<title>Boost.Python - <boost/python/return_by_value.hpp></title>
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	<body>
	<table border="0" cellpadding="7" cellspacing="0" width="100%" summary=
	"header">
	<tr>
	<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>
	</td>

	<td valign="top">
	<h1 align="center"><a href="../index.html">Boost.Python</a></h1>

	<h2 align="center">Header
	<boost/python/return_by_value.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="#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>
	</dl>
	</dd>
	</dl>
	</dd>

	<dt><a href="#examples">Example</a></dt>
	</dl>
	<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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