boost_1_45_0/libs/python/doc/v2/to_python_indirect.html - nest-learning-thermostat/5.1.7/boost - Git at Google

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     <title>Boost.Python - &lt;boost/python/to_python_indirect.hpp&gt;</title>

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

           <h2 align="center">Header &lt;boost/python/to_python_indirect.hpp&gt;</h2>
     </table>
     <hr>

     <h2>Contents</h2>

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


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

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

           <dd>
             <dl class="page-index">

               <dt><a href="#to_python_indirect-spec-synopsis">Class Template
               <code>to_python_indirect</code> synopsis</a>

               <dt><a href="#to_python_indirect-spec-observers">Class Template
               <code>to_python_indirect</code> observer functions</a>

               <dt><a href="#to_python_indirect-spec-statics">Class Template
               <code>to_python_indirect</code> static functions</a>
             </dl>
         </dl>

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

     <h2><a name="introduction"></a>Introduction</h2>

     <code>&lt;boost/python/to_python_indirect.hpp&gt;</code> supplies
     a way to construct new Python objects that hold wrapped C++ class
     instances via a pointer or smart pointer.

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

     <h3><a name="to_python_indirect-spec"></a>Class template <code>to_python_indirect</code></h3>
     <p>Class template <code>to_python_indirect</code> converts objects
 of its first argument type to python as extension class instances, using the ownership policy provided by its 2nd argument.

     <p>


     <table border="1" summary="to_python_indirect template parameters">
       <caption>
         <b><code>to_python_indirect</code> Requirements</b><br>

         In the table below, <b><code>x</code></b> denotes an object of
         type <code>T</code>, <b><code>h</code></b> denotes an
         object of type
         <code>boost::python::objects::instance_holder*</code>, and
         <b><code>p</code></b> denotes an object of type
         <code>U*</code>.

       </caption>
       <tr>
         <th>Parameter

         <th>Requirements

         <th>Description

       <tr>
         <td><code>T</code>

         <td>Either <code>U</code>&nbsp;<i>cv</i><code>&amp;</code>
         (where <i>cv</i> is any optional cv-qualification) or a <a
         href="Dereferenceable.html">Dereferenceable</a> type such that
         <code>*x</code> is convertible to <code>U const&amp;</code>, where
         <code>U</code> is a class type.

         <td>A type deferencing a C++ class exposed to Python using
         class template <code><a
         href="class.html#class_-spec">class_</a></code>.

       <tr>
         <td><code>MakeHolder</code>

         <td>h = MakeHolder::execute(p);

         <td>A class whose static <code>execute()</code> creates an
         <code>instance_holder</code>.

     </table>

     Instantiations of <code>to_python_indirect</code> are models of <a
     href="ResultConverter.html#ResultConverter-concept">ResultConverter</a>.


     <h4><a name="to_python_indirect-spec-synopsis"></a>Class template <code>to_python_indirect</code> synopsis</h4>
 <pre>
 namespace boost { namespace python
 {
   template &lt;class T, class MakeHolder&gt;
   struct to_python_indirect
   {
      static bool convertible();
      PyObject* operator()(T ptr_or_reference) const;
    private:
      static PyTypeObject* type();
   };
 }}
 </pre>

     <h4><a name="to_python_indirect-spec-observers"></a>Class template <code>to_python_indirect</code> observers</h4>
 <pre>
 PyObject* operator()(T x) const;
 </pre>

     <dl class="function-semantics">

       <dt><b>Requires:</b> <code>x</code> refers to an object (if it
       is a pointer type, it is non-null). <code>convertible() ==
       true</code>.

       <dt><b>Effects:</b> Creates an appropriately-typed Boost.Python
       extension class instance, uses <code>MakeHolder</code> to create
       an <code>instance_holder</code> from <code>x</code>, installs
       the <code>instance_holder</code> in the new extension class
       instance, and returns a pointer to it.

     </dl>


     <h4><a name="to_python_indirect-spec-statics"></a>Class template <code>to_python_indirect</code> statics</h4>
 <pre>
 bool convertible();
 </pre>

       <dt><b>Effects:</b> Returns <code>true</code> iff any module has
       registered a Python type corresponding to <code>U</code>.

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

 This example replicates the functionality of <a
 href="reference_existing_object.html#reference_existing_object-spec">reference_existing_object</a>,
 but without some of the compile-time error checking.


 <pre>

 struct make_reference_holder
 {
    typedef boost::python::objects::instance_holder* result_type;
    template &lt;class T&gt;
    static result_type execute(T* p)
    {
       return new boost::python::objects::pointer_holder&lt;T*, T&gt;(p);
    }
 };

 struct reference_existing_object
 {
    // metafunction returning the <a href="ResultConverter.html#ResultConverter-concept">ResultConverter</a>
    template &lt;class T&gt;
    struct apply
    {
       typedef boost::python::to_python_indirect&lt;T,make_reference_holder&gt; type;
    };
 };
 </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><i>&copy; Copyright <a href="http://www.boost.org/people/dave_abrahams.htm">Dave
     Abrahams</a> 2002. </i> Distributed
   under the Boost Software License, Version 1.0. (See accompanying file
   LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)</p>
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	<meta name="generator" content="HTML Tidy, see www.w3.org">
	<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
	<link rel="stylesheet" type="text/css" href="../boost.css">

	<title>Boost.Python - <boost/python/to_python_indirect.hpp></title>

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

	<h2 align="center">Header <boost/python/to_python_indirect.hpp></h2>
	</table>
	<hr>

	<h2>Contents</h2>

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


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

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

	<dd>
	<dl class="page-index">

	<dt><a href="#to_python_indirect-spec-synopsis">Class Template
	<code>to_python_indirect</code> synopsis</a>

	<dt><a href="#to_python_indirect-spec-observers">Class Template
	<code>to_python_indirect</code> observer functions</a>

	<dt><a href="#to_python_indirect-spec-statics">Class Template
	<code>to_python_indirect</code> static functions</a>
	</dl>
	</dl>

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

	<h2><a name="introduction"></a>Introduction</h2>

	<code><boost/python/to_python_indirect.hpp></code> supplies
	a way to construct new Python objects that hold wrapped C++ class
	instances via a pointer or smart pointer.

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

	<h3><a name="to_python_indirect-spec"></a>Class template <code>to_python_indirect</code></h3>
	<p>Class template <code>to_python_indirect</code> converts objects
	of its first argument type to python as extension class instances, using the ownership policy provided by its 2nd argument.

	<p>


	<table border="1" summary="to_python_indirect template parameters">
	<caption>
	<b><code>to_python_indirect</code> Requirements</b><br>

	In the table below, <b><code>x</code></b> denotes an object of
	type <code>T</code>, <b><code>h</code></b> denotes an
	object of type
	<code>boost::python::objects::instance_holder*</code>, and
	<b><code>p</code></b> denotes an object of type
	<code>U*</code>.

	</caption>
	<tr>
	<th>Parameter

	<th>Requirements

	<th>Description

	<tr>
	<td><code>T</code>

	<td>Either <code>U</code> <i>cv</i><code>&</code>
	(where <i>cv</i> is any optional cv-qualification) or a <a
	href="Dereferenceable.html">Dereferenceable</a> type such that
	<code>*x</code> is convertible to <code>U const&</code>, where
	<code>U</code> is a class type.

	<td>A type deferencing a C++ class exposed to Python using
	class template <code><a
	href="class.html#class_-spec">class_</a></code>.

	<tr>
	<td><code>MakeHolder</code>

	<td>h = MakeHolder::execute(p);

	<td>A class whose static <code>execute()</code> creates an
	<code>instance_holder</code>.

	</table>

	Instantiations of <code>to_python_indirect</code> are models of <a
	href="ResultConverter.html#ResultConverter-concept">ResultConverter</a>.


	<h4><a name="to_python_indirect-spec-synopsis"></a>Class template <code>to_python_indirect</code> synopsis</h4>
	<pre>
	namespace boost { namespace python
	{
	template <class T, class MakeHolder>
	struct to_python_indirect
	{
	static bool convertible();
	PyObject* operator()(T ptr_or_reference) const;
	private:
	static PyTypeObject* type();
	};
	}}
	</pre>

	<h4><a name="to_python_indirect-spec-observers"></a>Class template <code>to_python_indirect</code> observers</h4>
	<pre>
	PyObject* operator()(T x) const;
	</pre>

	<dl class="function-semantics">

	<dt><b>Requires:</b> <code>x</code> refers to an object (if it
	is a pointer type, it is non-null). <code>convertible() ==
	true</code>.

	<dt><b>Effects:</b> Creates an appropriately-typed Boost.Python
	extension class instance, uses <code>MakeHolder</code> to create
	an <code>instance_holder</code> from <code>x</code>, installs
	the <code>instance_holder</code> in the new extension class
	instance, and returns a pointer to it.

	</dl>


	<h4><a name="to_python_indirect-spec-statics"></a>Class template <code>to_python_indirect</code> statics</h4>
	<pre>
	bool convertible();
	</pre>

	<dt><b>Effects:</b> Returns <code>true</code> iff any module has
	registered a Python type corresponding to <code>U</code>.

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

	This example replicates the functionality of <a
	href="reference_existing_object.html#reference_existing_object-spec">reference_existing_object</a>,
	but without some of the compile-time error checking.


	<pre>

	struct make_reference_holder
	{
	typedef boost::python::objects::instance_holder* result_type;
	template <class T>
	static result_type execute(T* p)
	{
	return new boost::python::objects::pointer_holder<T*, T>(p);
	}
	};

	struct reference_existing_object
	{
	// metafunction returning the <a href="ResultConverter.html#ResultConverter-concept">ResultConverter</a>
	template <class T>
	struct apply
	{
	typedef boost::python::to_python_indirect<T,make_reference_holder> type;
	};
	};
	</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><i>© Copyright <a href="http://www.boost.org/people/dave_abrahams.htm">Dave
	Abrahams</a> 2002. </i> Distributed
	under the Boost Software License, Version 1.0. (See accompanying file
	LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)</p>