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<h2><span class="refentrytitle">Function dynamic_any_cast</span></h2>
<p>boost::type_erasure::dynamic_any_cast</p>
</div>
<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
<div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: <<a class="link" href="../../boost_typeerasure/reference.html#header.boost.type_erasure.dynamic_any_cast_hpp" title="Header <boost/type_erasure/dynamic_any_cast.hpp>">boost/type_erasure/dynamic_any_cast.hpp</a>>
</span>
<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> R<span class="special">,</span> <span class="keyword">typename</span> Any<span class="special">></span> <span class="identifier">R</span> <span class="identifier">dynamic_any_cast</span><span class="special">(</span><span class="identifier">Any</span> <span class="special">&&</span> arg<span class="special">)</span><span class="special">;</span>
<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> R<span class="special">,</span> <span class="keyword">typename</span> Any<span class="special">,</span> <span class="keyword">typename</span> Map<span class="special">></span>
<span class="identifier">R</span> <span class="identifier">dynamic_any_cast</span><span class="special">(</span><span class="identifier">Any</span> <span class="special">&&</span> arg<span class="special">,</span> <span class="keyword">const</span> <a class="link" href="static_binding.html" title="Struct template static_binding">static_binding</a><span class="special"><</span> <span class="identifier">Map</span> <span class="special">></span> <span class="special">&</span><span class="special">)</span><span class="special">;</span></pre></div>
<div class="refsect1">
<a name="idm45555078952480"></a><h2>Description</h2>
<p>Downcasts or crosscasts an <code class="computeroutput"><a class="link" href="any.html" title="Class template any">any</a></code>.</p>
<p>
The single argument form can only be used when <code class="computeroutput">R</code> uses a single non-deduced placeholder.</p>
<p>
Example: </p>
<pre class="programlisting"><span class="comment">// Assume that typeid_<>, copy_constructible<>, and incrementable<></span>
<span class="comment">// have all been registered for int.</span>
<span class="identifier">any</span><span class="special"><</span><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="identifier">typeid_</span><span class="special"><</span><span class="special">></span><span class="special">,</span> <span class="identifier">copy_constructible</span><span class="special"><</span><span class="special">></span> <span class="special">></span> <span class="special">></span> <span class="identifier">x</span><span class="special">(</span><span class="number">1</span><span class="special">)</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="identifier">any</span><span class="special"><</span>
<span class="identifier">mpl</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span>
<span class="identifier">typeid_</span><span class="special"><</span><span class="special">></span><span class="special">,</span>
<span class="identifier">copy_constructible</span><span class="special"><</span><span class="special">></span><span class="special">,</span>
<span class="identifier">incrementable</span><span class="special"><</span><span class="special">></span>
<span class="special">></span>
<span class="special">></span> <span class="identifier">incrementable_any</span><span class="special">;</span>
<span class="keyword">auto</span> <span class="identifier">y</span> <span class="special">=</span> <span class="identifier">dynamic_any_cast</span><span class="special"><</span><span class="identifier">incrementable_any</span><span class="special">></span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span><span class="special">;</span>
<span class="special">++</span><span class="identifier">y</span><span class="special">;</span>
<span class="identifier">assert</span><span class="special">(</span><span class="identifier">any_cast</span><span class="special"><</span><span class="keyword">int</span><span class="special">></span><span class="special">(</span><span class="identifier">y</span><span class="special">)</span> <span class="special">==</span> <span class="number">2</span><span class="special">)</span><span class="special">;</span>
</pre>
<p> </p>
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<td><p><span class="term">Requires:</span></p></td>
<td><p><code class="computeroutput">R</code> and <code class="computeroutput">Any</code> must both be specializations of <a class="link" href="any.html" title="Class template any">any</a>. </p></td>
</tr>
<tr>
<td><p><span class="term">Requires:</span></p></td>
<td><p>PlaceholderMap must be an MPL map with a key for every non-deduced placeholder used by R. The value associated with each key should be the corresponding placeholder in Any. </p></td>
</tr>
<tr>
<td><p><span class="term">Requires:</span></p></td>
<td><p>The concept of Any must include <a class="link" href="typeid_.html" title="Struct template typeid_">typeid_</a>, for every <a class="link" href="placeholder.html" title="Struct placeholder">placeholder</a> which is used by R.</p></td>
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<td><p><span class="term">Throws:</span></p></td>
<td>
<a class="link" href="../bad_any_cast.html" title="Class bad_any_cast">bad_any_cast</a> if the concepts used by R were not previously registered via a call to register_binding.</td>
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<td align="right"><div class="copyright-footer">Copyright © 2011-2013 Steven Watanabe<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt 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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