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<a name="any.reference"></a>Reference</h2></div></div></div>
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<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>
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<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 compact" style="list-style-type: disc; ">
<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">The destructor for a
<span class="emphasis"><em>ValueType</em></span> upholds the no-throw
exception-safety guarantee.</li>
</ul></div>
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<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">void</span> <a class="link" href="../boost/swap_idm45507162621920.html" title="Function swap"><span class="identifier">swap</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> <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_idm45507162615824.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_idm45507162615824.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_idm45507162615824.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_idm45507162615824.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_idm45507162615824.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>
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<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>)
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