105 lines
3.7 KiB
HTML
105 lines
3.7 KiB
HTML
<!doctype HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|
<html>
|
|
<!--
|
|
(C) Copyright 2002-4 Robert Ramey - http://www.rrsd.com .
|
|
Use, modification and distribution is subject to 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)
|
|
-->
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
|
|
<link rel="stylesheet" type="text/css" href="../../../boost.css">
|
|
<link rel="stylesheet" type="text/css" href="style.css">
|
|
<title>Serialization - BOOST_STATIC_WARNING</title>
|
|
</head>
|
|
<body link="#0000ff" vlink="#800080">
|
|
<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">Serialization</h1>
|
|
<h2 align="center"><code>void_cast</code></h2>
|
|
</td>
|
|
</tr>
|
|
</table>
|
|
<hr>
|
|
<h3>Motivation</h3>
|
|
C++ includes the operator <code style="white-space: normal">dynamic_cast<T>(U * u)</code>
|
|
for casting a pointer at runtime between two related types. However, this can only be
|
|
used for polymorphic classes. That is, it can only be used with related classes which have at least one virtual function.
|
|
Limiting the serializaton of pointers to only such classes would diminish the applicability
|
|
of the library.
|
|
|
|
<h3>Usage</h3>
|
|
|
|
The following functions are defined in the header
|
|
<a target="void_cast" href="../../../boost/serialization/void_cast.hpp">void_cast.hpp</a>.
|
|
They are declared in the namespace
|
|
<code style="white-space: normal">boost::serialization</code>.
|
|
|
|
<dl>
|
|
<dt><h4><pre><code>
|
|
template<class Derived, class Base>
|
|
const void_cast_detail::void_caster &
|
|
void_cast_register(
|
|
Derived const * derived = NULL,
|
|
Base * const base = NULL
|
|
);
|
|
</code></pre></h4></dt>
|
|
<dd>
|
|
This function "registers" a pair of related types. It stores the fact that
|
|
<code style="white-space: normal">Derived</code> is immediately derived from
|
|
<code style="white-space: normal">Base</code> in a global table.
|
|
<ul>
|
|
<li>This "registration" can be invoked anywhere in the program. The table is built at
|
|
pre-runtime and is available anywhere else in the program.
|
|
<li>only adjacent base/derived pairs need be registered. That is,
|
|
<pre><code>
|
|
void_cast_register<A, B>();
|
|
void_cast_register<B, C>();
|
|
</code></pre>
|
|
automatically derives the fact that A can be upcast to C and vice-versa.
|
|
</ul>
|
|
</dd>
|
|
|
|
<dt><h4><pre><code>
|
|
void *
|
|
void_upcast(
|
|
extended_type_info const & derived_type,
|
|
extended_type_info const & base_type,
|
|
void * const t
|
|
);
|
|
</code></pre></h4></dt>
|
|
|
|
<dt><h4><pre><code>
|
|
void *
|
|
void_downcast(
|
|
extended_type_info const & derived_type,
|
|
extended_type_info const & base_type,
|
|
void * const t
|
|
);
|
|
</code></pre></h4></dt>
|
|
<dd>
|
|
These functions cast a void pointer from one type to another. The source and
|
|
definition types are specified by passing references to the corresponding
|
|
<a href="extended_type_info.html"><code style="white-space: normal">
|
|
extended_type_info</code></a>
|
|
records. An attempt to cast between types not "registered" with
|
|
<code style="white-space: normal">void_cast_register</code>
|
|
will throw a
|
|
<a href="exceptions.html"><code style="white-space: normal">boost::archive::archive_exception</code></a>
|
|
with value equal to
|
|
<code style="white-space: normal">unregistered_cast</code>
|
|
</dd>
|
|
</dl>
|
|
|
|
<hr>
|
|
<p><i>© Copyright <a href="http://www.rrsd.com">Robert Ramey</a> 2002-2004.
|
|
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)
|
|
</i></p>
|
|
</body>
|
|
</html>
|