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diff --git a/libs/python/doc/v2/to_python_converter.html b/libs/python/doc/v2/to_python_converter.html new file mode 100644 index 0000000000..81b61d252b --- /dev/null +++ b/libs/python/doc/v2/to_python_converter.html @@ -0,0 +1,227 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<!-- Copyright David Abrahams 2006. 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) --> +<html> + <head> + <meta name="generator" content= + "HTML Tidy for Windows (vers 1st August 2002), 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_converter.hpp></title> + </head> + + <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/to_python_converter.hpp></h2> + </td> + </tr> + </table> + <hr> + + <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="#to_python_converter-spec">Class Template + <code>to_python_converter</code></a></dt> + + <dd> + <dl class="page-index"> + <dt><a href="#to_python_converter-spec-synopsis">Class Template + <code>to_python_converter</code> synopsis</a></dt> + + <dt><a href="#to_python_converter-spec-ctors">Class Template + <code>to_python_converter</code> constructor</a></dt> + </dl> + </dd> + </dl> + </dd> + + <dt><a href="#examples">Example</a></dt> + </dl> + <hr> + + <h2><a name="introduction"></a>Introduction</h2> + <code>to_python_converter</code> registers a conversion from objects of a + given C++ type into a Python object. + + <h2><a name="classes"></a>Classes</h2> + + <h3><a name="to_python_converter-spec"></a>Class template + <code>to_python_converter</code></h3> + <code>to_python_converter</code> adds a wrapper around a static member + function of its second template parameter, handling low-level details + such as insertion into the converter registry. + + <table border="1" summary="to_python_converter template parameters"> + <caption> + <b><code>to_python_converter</code> template parameters</b><br> + In the table below, <b><code>x</code></b> denotes an object of type + <code>T</code> + </caption> + + <tr> + <th>Parameter</th> + + <th>Requirements</th> + + <th>Description</th> + </tr> + + <tr> + <td><code>T</code></td> + + <td> + </td> + + <td>The C++ type of the source object in the conversion</td> + </tr> + + <tr> + <td><code>Conversion</code></td> + + <td> + <code>PyObject* p = Conversion::convert(x)</code>,<br> + if <code>p == 0</code>, <code><a href= + "http://www.python.org/doc/2.2/api/exceptionHandling.html#l2h-71">PyErr_Occurred</a>() != 0</code>.</td> + + <td>A class type whose static member function <code>convert</code> + does the real work of the conversion.</td> + </tr> + <tr> + <td><code>bool has_get_pytype = false</code></td> + + <td> + <code>PyTypeObject const * p = Conversion::get_pytype() </code>.</td> + + <td><b>Optional member</b> - if <code>Conversion</code> has <code>get_pytype</code> member supply + <code>true</code> for this parameters. + If present <code>get_pytype</code> is used to document the return type + of functions using this conversion. The <code>get_pytype</code> may be implemented + using the classes and functions + from <a href="pytype_function.html"><code>pytype_function.hpp</code></a> + <b>NOTE :</b> For backward compatibility this parameter may be passed after + checking if <code>BOOST_PYTHON_SUPPORTS_PY_SIGNATURES</code> is defined (see + <a href="pytype_function.html#examples">here</a>). + </td> + </tr> + </table> + + <h4><a name="to_python_converter-spec-synopsis"></a>Class template + <code>to_python_converter</code> synopsis</h4> +<pre> +namespace boost { namespace python +{ + template <class T, class Conversion, bool convertion_has_get_pytype_member=false> + struct to_python_converter + { + to_python_converter(); + }; +}} +</pre> + + <h4><a name="to_python_converter-spec-ctors"></a>Class template + <code>to_python_converter</code> constructor</h4> +<pre> +to_python_converter(); +</pre> + + <dl class="function-semantics"> + <dt><b>Effects:</b> Registers a to_python converter which uses + <code>Conversion::convert()</code> to do its work.</dt> + </dl> + + <h2><a name="examples"></a>Example</h2> + This example presumes that someone has implemented the standard <a href= + "http://www.python.org/doc/2.2/ext/dnt-basics.html">noddy example + module</a> from the Python documentation, and placed the corresponding + declarations in <code>"noddy.h"</code>. Because + <code>noddy_NoddyObject</code> is the ultimate trivial extension type, + the example is a bit contrived: it wraps a function for which all + information is contained in the <i>type</i> of its return value. + + <h3>C++ module definition</h3> +<pre> +#include <boost/python/reference.hpp> +#include <boost/python/module.hpp> +#include "noddy.h" + +struct tag {}; +tag make_tag() { return tag(); } + +using namespace boost::python; + +struct tag_to_noddy +{ + static PyObject* convert(tag const& x) + { + return PyObject_New(noddy_NoddyObject, &noddy_NoddyType); + } + static PyTypeObject const* get_pytype() + { + return &noddy_NoddyType; + } +}; + +BOOST_PYTHON_MODULE(to_python_converter) +{ + def("make_tag", make_tag); + to_python_converter<tag, tag_to_noddy, true>(); //"true" because tag_to_noddy has member get_pytype +} +</pre> + + <h3>Python code</h3> +<pre> +>>> import to_python_converter +>>> def always_none(): +... return None +... +>>> def choose_function(x): +... if (x % 2 != 0): +... return to_python_converter.make_tag +... else: +... return always_none +... +>>> a = [ choose_function(x) for x in range(5) ] +>>> b = [ f() for f in a ] +>>> type(b[0]) +<type 'NoneType'> +>>> type(b[1]) +<type 'Noddy'> +>>> type(b[2]) +<type 'NoneType'> +>>> type(b[3]) +<type 'Noddy'> +</pre> + + <p>Revised + <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan --> + 11 June, 2007 + <!--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> + </body> +</html> + |