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  28 <a name="any.reference"></a>Reference</h2></div></div></div>
  29 <div class="toc"><dl class="toc">
  30 <dt><span class="section"><a href="reference.html#any.ValueType"><span class="emphasis"><em>ValueType</em></span> requirements</a></span></dt>
  31 <dt><span class="section"><a href="reference.html#header.boost.any_hpp">Header &lt;boost/any.hpp&gt;</a></span></dt>
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  34 <div class="titlepage"><div><div><h3 class="title">
  35 <a name="any.ValueType"></a><span class="emphasis"><em>ValueType</em></span> requirements</h3></div></div></div>
  36 <p>Values are strongly informational objects for which
  37       identity is not significant, i.e. the focus is principally on
  38       their state content and any behavior organized around
  39       that. Another distinguishing feature of values is their
  40       granularity: normally fine-grained objects representing simple
  41       concepts in the system such as quantities.</p>
  42 <p>As the emphasis of a value lies in its state not its
  43       identity, values can be copied and typically assigned one to
  44       another, requiring the explicit or implicit definition of a
  45       public copy constructor and public assignment operator. Values
  46       typically live within other scopes, i.e. within objects or
  47       blocks, rather than on the heap. Values are therefore normally
  48       passed around and manipulated directly as variables or through
  49       references, but not as pointers that emphasize identity and
  50       indirection.</p>
  51 <p>The specific requirements on value types to be used in an
  52       <code class="computeroutput"><a class="link" href="../boost/any.html" title="Class any">any</a></code>
  53       are:</p>
  54 <div class="itemizedlist"><ul class="itemizedlist compact" style="list-style-type: disc; ">
  55 <li class="listitem">A <span class="emphasis"><em>ValueType</em></span> is
  56           <span class="emphasis"><em>CopyConstructible</em></span> [20.1.3].</li>
  57 <li class="listitem">The destructor for a
  58         <span class="emphasis"><em>ValueType</em></span> upholds the no-throw
  59         exception-safety guarantee.</li>
  60 </ul></div>
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  63 <div class="titlepage"><div><div><h3 class="title">
  64 <a name="header.boost.any_hpp"></a>Header &lt;<a href="../../../boost/any.hpp" target="_top">boost/any.hpp</a>&gt;</h3></div></div></div>
  65 <pre class="synopsis"><span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span>
  66   <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>
  67   <span class="keyword">class</span> <a class="link" href="../boost/any.html" title="Class any">any</a><span class="special">;</span>
  68   <span class="keyword">void</span> <a class="link" href="../boost/swap_idp424614880.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">&amp;</span><span class="special">,</span> <a class="link" href="../boost/any.html" title="Class any">any</a> <span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
  69   <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span> <span class="identifier">T</span> <a class="link" href="../boost/any_cast_idp424620208.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">&amp;</span><span class="special">)</span><span class="special">;</span>
  70   <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span> <span class="identifier">T</span> <a class="link" href="../boost/any_cast_idp424620208.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">&amp;&amp;</span><span class="special">)</span><span class="special">;</span>
  71   <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span> <span class="identifier">T</span> <a class="link" href="../boost/any_cast_idp424620208.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">&amp;</span><span class="special">)</span><span class="special">;</span>
  72   <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> ValueType<span class="special">&gt;</span> <span class="keyword">const</span> <span class="identifier">ValueType</span> <span class="special">*</span> <a class="link" href="../boost/any_cast_idp424620208.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>
  73   <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> ValueType<span class="special">&gt;</span> <span class="identifier">ValueType</span> <span class="special">*</span> <a class="link" href="../boost/any_cast_idp424620208.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>
  74 <span class="special">}</span></pre>
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  79 <td align="right"><div class="copyright-footer">Copyright &#169; 2001 Kevlin Henney<p>Distributed under the Boost Software License, Version 1.0.
  80       (See accompanying file <code class="filename">LICENSE_1_0.txt</code> or copy at
  81       <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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