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| <h2><span class="refentrytitle">Struct template when<Grammar, Fun *></span></h2> |
| <p>boost::proto::when<Grammar, Fun *> — A specialization that treats function pointer <a class="link" href="../../Transform.html" title="Concept Transform">Transform</a>s as if they |
| were function type <a class="link" href="../../Transform.html" title="Concept Transform">Transform</a>s.</p> |
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| <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="../../proto/reference.html#header.boost.proto.transform.when_hpp" title="Header <boost/proto/transform/when.hpp>">boost/proto/transform/when.hpp</a>> |
| |
| </span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> Grammar<span class="special">,</span> <span class="keyword">typename</span> Fun<span class="special">></span> |
| <span class="keyword">struct</span> <a class="link" href="when_Grammar__Fun_id1297061.html" title="Struct template when<Grammar, Fun *>">when</a><span class="special"><</span><span class="identifier">Grammar</span><span class="special">,</span> <span class="identifier">Fun</span> <span class="special">*</span><span class="special">></span> <span class="special">:</span> <span class="keyword"></span> <a class="link" href="when.html" title="Struct template when">proto::when</a><span class="special"><</span> <span class="identifier">Grammar</span><span class="special">,</span> <span class="identifier">Fun</span> <span class="special">></span> <span class="special">{</span> |
| <span class="special">}</span><span class="special">;</span></pre></div> |
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| <a name="id2448067"></a><h2>Description</h2> |
| <p> |
| This specialization requires that <code class="computeroutput">Fun</code> is actually a function type. |
| </p> |
| <p> |
| This specialization is required for nested transforms such as |
| <code class="computeroutput">proto::when<G, T0(T1(_))></code>. In C++, functions that are used |
| as parameters to other functions automatically decay to funtion pointer types. In other words, the |
| type <code class="computeroutput">T0(T1(_))</code> is indistinguishable from |
| <code class="computeroutput">T0(T1(*)(_))</code>. This specialization is required to handle these |
| nested function pointer type transforms properly. |
| </p> |
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| <td align="right"><div class="copyright-footer">Copyright © 2008 Eric Niebler<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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