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diff --git a/libs/python/doc/v2/ptr.html b/libs/python/doc/v2/ptr.html new file mode 100644 index 000000000..4aca53915 --- /dev/null +++ b/libs/python/doc/v2/ptr.html @@ -0,0 +1,265 @@ +<!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=iso-8859-1"> + <link rel="stylesheet" type="text/css" href="../boost.css"> + + <title>Boost.Python - <boost/python/ptr.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/ptr.hpp></h2> + </table> + <hr> + + <h2>Contents</h2> + + <dl class="page-index"> + <dt><a href="#introduction">Introduction</a> + + <dt><a href="#functions">Functions</a> + <dd> + <dl class="page-index"> + <dt><a href="#ptr-spec">ptr</a> + </dl> + + <dt><a href="#classes">Classes</a> + <dd> + <dl class="page-index"> + <dt><a href="#pointer_wrapper-spec">Class template <code>pointer_wrapper</code></a> + + <dd> + <dl class="page-index"> + <dt><a href="#pointer_wrapper-spec-synopsis">Class template <code>pointer_wrapper</code> synopsis</a> + + <dt><a href="#pointer_wrapper-spec-types">Class + <code>pointer_wrapper</code> types</a> + + <dt><a href="#pointer_wrapper-spec-ctors">Class + <code>pointer_wrapper</code> constructors and destructor</a> + + <dt><a href="#pointer_wrapper-spec-observers">Class + <code>pointer_wrapper</code> observer functions</a> + + </dl> + </dl> + + <dt><a href="#metafunctions">Metafunctions</a> + <dd> + <dl class="page-index"> + <dt><a href="#is_pointer_wrapper-spec">Class template <code>is_pointer_wrapper</code></a> + + <dd> + <dl class="page-index"> + <dt><a href="#is_pointer_wrapper-spec-synopsis">Class template <code>is_pointer_wrapper</code> synopsis</a> + </dl> + + + <dt><a href="#unwrap_pointer-spec">Class template <code>unwrap_pointer</code></a> + + <dd> + <dl class="page-index"> + <dt><a href="#unwrap_pointer-spec-synopsis">Class template <code>unwrap_pointer</code> synopsis</a> + </dl> + + </dl> + + + <dt><a href="#examples">Example(s)</a> + </dl> + <hr> + + <h2><a name="introduction"></a>Introduction</h2> + + <p><code><boost/python/ptr.hpp></code> defines the + <code>ptr()</code> function template, which allows users to + specify how to convert C++ pointer values to python in the context + of implementing overridable virtual functions, invoking Python + callable objects, or explicitly converting C++ objects to + Python. Normally, when passing pointers to Python callbacks, the + pointee is copied to ensure that the Python object + never holds a dangling reference. To specify that the new Python + object should merely contain a copy of a pointer <code>p</code>, + the user can pass <code><a href="#ptr-spec">ptr</a>(p)</code> instead of passing + <code>p</code> directly. This interface is meant to mirror the use + of <a href="../../../bind/ref.html"><code>boost::ref()</code></a>, + which can be similarly used to prevent copying of referents. + + <p><code>ptr(p)</code> returns an instance of <code><a + href="#pointer_wrapper-spec">pointer_wrapper<></a></code>, which + can be detected using the <code><a + href="#is_pointer_wrapper-spec">is_pointer_wrapper<></a></code> + metafunction; <code><a + href="#unwrap_pointer-spec">unwrap_pointer<></a></code> is a + metafunction which extracts the original pointer type from a + <code>pointer_wrapper<></code>. These classes can be thought + of as implementation details. + + <h2><a name="functions"></a>Functions</h2> +<pre> + +<a name="ptr-spec">template <class T></a> +pointer_wrapper<T> ptr(T x); +</pre> + + <dl class="ptr-semantics"> + <dt><b>Requires:</b> <code>T</code> is a pointer type. + + <dt><b>Returns:</b> <code><a href="#pointer_wrapper-spec">pointer_wrapper</a><T>(x)</code> + + <dt><b>Throws:</b> nothing. + </dl> + + <h2><a name="classes"></a>Classes</h2> + + <h3><a name="pointer_wrapper-spec"></a>Class template <code>pointer_wrapper</code></h3> + + <p>A "type envelope" which is returned by <a + href="#ptr-spec">ptr()</a>, used to indicate reference semantics + for pointers passed to Python callbacks. + + <h4><a name="pointer_wrapper-spec-synopsis"></a>Class + <code>pointer_wrapper</code> synopsis</h4> +<pre> +namespace boost { namespace python +{ + template<class Ptr> class pointer_wrapper + { + public: + typedef Ptr type; + + explicit pointer_wrapper(Ptr x); + operator Ptr() const; + Ptr get() const; + }; +}} +</pre> + + <h4><a name="pointer_wrapper-spec-types"></a>Class template <code>pointer_wrapper</code> types</h4> +<pre> +typedef Ptr type; +</pre> +The type of the pointer being wrapped. + + <h4><a name="pointer_wrapper-spec-ctors"></a>Class template <code>pointer_wrapper</code> constructors and + destructor</h4> +<pre> +explicit pointer_wrapper(Ptr x); +</pre> + + <dl class="function-semantics"> + <dt><b>Requires:</b> <code>Ptr</code> is a pointer type. + + <dt><b>Effects:</b> Stores <code>x</code> in a the <code>pointer_wrapper<></code>. + <dt><b>Throws:</b> nothing. + </dl> + + <h4><a name="pointer_wrapper-spec-observers"></a>Class template <code>pointer_wrapper</code> observer + functions</h4> +<pre> +operator Ptr() const; +Ptr get() const; +</pre> + + <dl class="function-semantics"> + <dt><b>Returns:</b> a copy of the stored pointer. + <dt><b>Rationale:</b> <code>pointer_wrapper</code> is intended + to be a stand-in for the actual pointer type, but sometimes it's + better to have an explicit way to retrieve the pointer. + </dl> + + <h2><a name="metafunctions"></a>Metafunctions</h2> + + <h3><a name="is_pointer_wrapper-spec"></a>Class template <code>is_pointer_wrapper</code></h3> + + <p>A unary metafunction whose <code>value</code> is true iff its + argument is a <code>pointer_wrapper<></code>. + + <h4><a name="is_pointer_wrapper-spec-synopsis"></a>Class template <code>is_pointer_wrapper</code> synopsis</h4> +<pre> +namespace boost { namespace python +{ + template<class T> class is_pointer_wrapper + { + static <i>unspecified</i> value = ...; + }; +}} +</pre> + + + <dl class="metafunction-semantics"> + <dt><b>Returns:</b> <code>true</code> iff <code>T</code> is a + specialization of +<code>pointer_wrapper<></code>. +<dt><code>value</code> is an integral constant convertible to bool of +unspecified type + + </dl> + +<h3><a name="unwrap_pointer-spec"></a>Class template <code>unwrap_pointer</code></h3> + +A unary metafunction which extracts the wrapped pointer type from a +specialization of <code>pointer_wrapper<></code>. + + <h4><a name="unwrap_pointer-spec-synopsis"></a>Class template <code>unwrap_pointer</code> synopsis</h4> +<pre> +namespace boost { namespace python +{ + template<class T> class unwrap_pointer + { + typedef <i>unspecified</i> type; + }; +}} +</pre> + + <dl class="metafunction-semantics"> + <dt><b>Returns:</b> <code>T::type</code> if <code>T</code> is a + specialization of +<code>pointer_wrapper<></code>, <code>T</code> otherwise + </dl> + + + <h2><a name="examples"></a>Example(s)</h2> + +This example illustrates the use of <code>ptr()</code> to prevent an +object from being copied: +<pre> +#include <boost/python/call.hpp> +#include <boost/python/ptr.hpp> + +class expensive_to_copy +{ + ... +}; + +void pass_as_arg(expensive_to_copy* x, PyObject* f) +{ + // call the Python function f, passing a Python object built around + // which refers to *x by-pointer. + // + // *** Note: ensuring that *x outlives the argument to f() is *** + // *** up to the user! Failure to do so could result in a crash! *** + + boost::python::call<void>(f, ptr(x)); +} +... +</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> + |