| <html> |
| <head> |
| <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> |
| <title>Reference</title> |
| <link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css"> |
| <meta name="generator" content="DocBook XSL Stylesheets V1.75.2"> |
| <link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> |
| <link rel="up" href="../any.html" title="Chapter 2. Boost.Any"> |
| <link rel="prev" href="s02.html" title="Examples"> |
| <link rel="next" href="../boost/bad_any_cast.html" title="Class bad_any_cast"> |
| </head> |
| <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> |
| <table cellpadding="2" width="100%"><tr> |
| <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../boost.png"></td> |
| <td align="center"><a href="../../../index.html">Home</a></td> |
| <td align="center"><a href="../../../libs/libraries.htm">Libraries</a></td> |
| <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> |
| <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> |
| <td align="center"><a href="../../../more/index.htm">More</a></td> |
| </tr></table> |
| <hr> |
| <div class="spirit-nav"> |
| <a accesskey="p" href="s02.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../any.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../boost/bad_any_cast.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> |
| </div> |
| <div class="section"> |
| <div class="titlepage"><div><div><h2 class="title" style="clear: both"> |
| <a name="any.reference"></a>Reference</h2></div></div></div> |
| <div class="toc"><dl> |
| <dt><span class="section"><a href="reference.html#any.ValueType"><span class="emphasis"><em>ValueType</em></span> requirements</a></span></dt> |
| <dt><span class="section"><a href="reference.html#header.boost.any_hpp">Header <boost/any.hpp></a></span></dt> |
| </dl></div> |
| <div class="section"> |
| <div class="titlepage"><div><div><h3 class="title"> |
| <a name="any.ValueType"></a><span class="emphasis"><em>ValueType</em></span> requirements</h3></div></div></div> |
| <p>Values are strongly informational objects for which |
| identity is not significant, i.e. the focus is principally on |
| their state content and any behavior organized around |
| that. Another distinguishing feature of values is their |
| granularity: normally fine-grained objects representing simple |
| concepts in the system such as quantities.</p> |
| <p>As the emphasis of a value lies in its state not its |
| identity, values can be copied and typically assigned one to |
| another, requiring the explicit or implicit definition of a |
| public copy constructor and public assignment operator. Values |
| typically live within other scopes, i.e. within objects or |
| blocks, rather than on the heap. Values are therefore normally |
| passed around and manipulated directly as variables or through |
| references, but not as pointers that emphasize identity and |
| indirection.</p> |
| <p>The specific requirements on value types to be used in an |
| <code class="computeroutput"><a class="link" href="../boost/any.html" title="Class any">any</a></code> |
| are:</p> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc" compact> |
| <li class="listitem">A <span class="emphasis"><em>ValueType</em></span> is |
| <span class="emphasis"><em>CopyConstructible</em></span> [20.1.3].</li> |
| <li class="listitem">A <span class="emphasis"><em>ValueType</em></span> is |
| optionally <span class="emphasis"><em>Assignable</em></span> [23.1]. The strong |
| exception-safety guarantee is required for all forms of |
| assignment.</li> |
| <li class="listitem">The destructor for a |
| <span class="emphasis"><em>ValueType</em></span> upholds the no-throw |
| exception-safety guarantee.</li> |
| </ul></div> |
| </div> |
| <div class="section"> |
| <div class="titlepage"><div><div><h3 class="title"> |
| <a name="header.boost.any_hpp"></a>Header <<a href="../../../boost/any.hpp" target="_top">boost/any.hpp</a>></h3></div></div></div> |
| <pre class="synopsis"><span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span> |
| <span class="keyword">class</span> <a class="link" href="../boost/bad_any_cast.html" title="Class bad_any_cast">bad_any_cast</a><span class="special">;</span> |
| <span class="keyword">class</span> <a class="link" href="../boost/any.html" title="Class any">any</a><span class="special">;</span> |
| <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> T<span class="special">></span> <span class="identifier">T</span> <a class="link" href="../boost/any_cast.html" title="Function any_cast"><span class="identifier">any_cast</span></a><span class="special">(</span><a class="link" href="../boost/any.html" title="Class any">any</a> <span class="special">&</span><span class="special">)</span><span class="special">;</span> |
| <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> T<span class="special">></span> <span class="identifier">T</span> <a class="link" href="../boost/any_cast.html" title="Function any_cast"><span class="identifier">any_cast</span></a><span class="special">(</span><span class="keyword">const</span> <a class="link" href="../boost/any.html" title="Class any">any</a> <span class="special">&</span><span class="special">)</span><span class="special">;</span> |
| <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> ValueType<span class="special">></span> <span class="keyword">const</span> <span class="identifier">ValueType</span> <span class="special">*</span> <a class="link" href="../boost/any_cast.html" title="Function any_cast"><span class="identifier">any_cast</span></a><span class="special">(</span><span class="keyword">const</span> <a class="link" href="../boost/any.html" title="Class any">any</a> <span class="special">*</span><span class="special">)</span><span class="special">;</span> |
| <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> ValueType<span class="special">></span> <span class="identifier">ValueType</span> <span class="special">*</span> <a class="link" href="../boost/any_cast.html" title="Function any_cast"><span class="identifier">any_cast</span></a><span class="special">(</span><a class="link" href="../boost/any.html" title="Class any">any</a> <span class="special">*</span><span class="special">)</span><span class="special">;</span> |
| <span class="special">}</span></pre> |
| </div> |
| </div> |
| <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> |
| <td align="left"></td> |
| <td align="right"><div class="copyright-footer">Copyright © 2001 Kevlin Henney<p>Distributed under the Boost Software License, Version 1.0. |
| (See accompanying file <code class="filename">LICENSE_1_0.txt</code> or copy at |
| <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) |
| </p> |
| </div></td> |
| </tr></table> |
| <hr> |
| <div class="spirit-nav"> |
| <a accesskey="p" href="s02.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../any.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../boost/bad_any_cast.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> |
| </div> |
| </body> |
| </html> |
