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diff --git a/libs/python/doc/v2/wrapper.html b/libs/python/doc/v2/wrapper.html new file mode 100644 index 000000000..06239754a --- /dev/null +++ b/libs/python/doc/v2/wrapper.html @@ -0,0 +1,238 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + <meta name="generator" content="HTML Tidy, see www.w3.org"> + <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> + <link rel="stylesheet" type="text/css" href="../boost.css"> + + <title>Boost.Python - <wrapper.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 <wrapper.hpp></h2> + </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="#override-spec">Class template + <code>override</code></a></dt> + + <dd> + <dl class="page-index"> + <dt><a href="#override-spec-synopsis">Class + <code>override</code> synopsis</a></dt> + + <dt><a href="#override-spec-observers">Class + <code>override</code> observer functions</a></dt> + </dl> + </dd> + + <dt><a href="#wrapper-spec">Class template + <code>wrapper</code></a></dt> + + <dd> + <dl class="page-index"> + <dt><a href="#wrapper-spec-synopsis">Class <code>wrapper</code> + synopsis</a></dt> + + <dt><a href="#wrapper-spec-observers">Class + <code>wrapper</code> observer functions</a></dt> + </dl> + </dd> + </dl> + </dd> + + <dt><a href="#examples">Example(s)</a></dt> + </dl> + <hr> + + <h2><a name="introduction"></a>Introduction</h2> + + <p>To wrap a class <code>T</code> such that its virtual functions can be + "overridden in Python"—so that the corresponding method of a Python + derived class will be called when the virtual function is invoked from + C++—you must create a C++ wrapper class derived from ``T`` that + overrides those virtual functions so that they call into Python. This + header contains classes that can be used to make that job easier.</p> + + <h2><a name="classes"></a>Classes</h2> + + <h3><a name="override-spec"></a>Class <code>override</code></h3> + + <p>Encapsulates a Python override of a C++ virtual function. An + <code>override</code> object either holds a callable Python object or + <code>None</code>.</p> + + <h4><a name="override-spec-synopsis"></a>Class <code>override</code> + synopsis</h4> +<pre> +namespace boost +{ + class override : object + { + public: + <i>unspecified</i> operator() const; + template <class A0> + <i>unspecified</i> operator(A0) const; + template <class A0, class A1> + <i>unspecified</i> operator(A0, A1) const; + ... + template <class A0, class A1, ...class A<i>n</i>> + <i>unspecified</i> operator(A0, A1, ...A<i>n</i>) const; + }; +}; +</pre> + + <h4><a name="override-spec-observers"></a>Class <code>override</code> + observer functions</h4> +<pre> +<i>unspecified</i> operator() const; +template <class A0> +<i>unspecified</i> operator(A0) const; +template <class A0, class A1> +<i>unspecified</i> operator(A0, A1) const; +... +template <class A0, class A1, ...class A<i>n</i>> +<i>unspecified</i> operator(A0, A1, ...A<i>n</i>) const; +</pre> + + <dl class="function-semantics"> + <dt><b>Effects:</b> If <code>*this</code> holds a callable Python + object, it is invoked with the specified arguments in the manner + specified <a href="callbacks.html">here</a>. Otherwise, throws <code><a + href="errors.html#error_already_set-spec">error_already_set</a></code> + .</dt> + + <dt><b>Returns:</b> An object of unspecified type that holds the Python + result of the invocation and, when converted to a C++ type + <code>R</code>, attempts to convert that result object to + <code>R</code>. If that conversion fails, throws <code><a href= + "errors.html#error_already_set-spec">error_already_set</a></code> + .</dt> + </dl> + + <h3><a name="wrapper-spec"></a>Class template <code>wrapper</code></h3> + + <p>Deriving your wrapper class from both ``T`` <i>and</i> + ``wrapper<T> makes writing that derived class easier.</p> + + <h4><a name="wrapper-spec-synopsis"></a>Class template + <code>wrapper</code> synopsis</h4> +<pre> +namespace boost +{ + class wrapper + { + protected: + override get_override(char const* name) const; + }; +}; +</pre> + + <h4><a name="wrapper-spec-observers"></a>Class <code>wrapper</code> + observer functions</h4> +<pre> +override get_override(char const* name) const; +</pre> + + <dl class="function-semantics"> + <dt><b>Requires:</b> <code>name</code> is a <a href= + "definitions.html#ntbs">ntbs</a>.</dt> + + <dt><b>Returns:</b> If <code>*this</code> is the C++ base class + subobject of a Python derived class instance that overrides the named + function, returns an <code>override</code> object that delegates to the + Python override. Otherwise, returns an <code>override</code> object + that holds <code>None</code>.</dt> + </dl> + + <h2><a name="examples"></a>Example</h2> +<pre> +#include <boost/python/module.hpp> +#include <boost/python/class.hpp> +#include <boost/python/wrapper.hpp> +#include <boost/python/call.hpp> + +using namespace boost::python; + +// Class with one pure virtual function +struct P +{ + virtual ~P(){} + virtual char const* f() = 0; + char const* g() { return "P::g()"; } +}; + +struct PCallback : P, wrapper<P> +{ + char const* f() + { +#if BOOST_WORKAROUND(BOOST_MSVC, <= 1300) // Workaround for vc6/vc7 + return call<char const*>(this->get_override("f").ptr()); +#else + return this->get_override("f")(); +#endif + } +}; + +// Class with one non-pure virtual function +struct A +{ + virtual ~A(){} + virtual char const* f() { return "A::f()"; } +}; + +struct ACallback : A, wrapper<A> +{ + char const* f() + { + if (override f = this->get_override("f")) +#if BOOST_WORKAROUND(BOOST_MSVC, <= 1300) // Workaround for vc6/vc7 + return call<char const*>(f.ptr()); +#else + return f(); +#endif + + return A::f(); + } + + char const* default_f() { return this->A::f(); } +}; + +BOOST_PYTHON_MODULE_INIT(polymorphism) +{ + class_<PCallback,boost::noncopyable>("P") + .def("f", pure_virtual(&P::f)) + ; + + class_<ACallback,boost::noncopyable>("A") + .def("f", &A::f, &ACallback::default_f) + ; +} +</pre> + + <p>Revised + <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan --> + 31 October, 2004 + <!--webbot bot="Timestamp" endspan i-checksum="39359" --> + + + <p><i>© Copyright <a href="http://www.boost.org/people/dave_abrahams.htm">Dave + Abrahams</a> 2004</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> + |