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  26 <a name="boost.proto.noinvoke"></a><div class="titlepage"></div>
  27 <div class="refnamediv">
  28 <h2><span class="refentrytitle">Struct template noinvoke</span></h2>
  29 <p>boost::proto::noinvoke &#8212; A type annotation in an <a class="link" href="../../ObjectTransform.html" title="Concept ObjectTransform">ObjectTransform</a> which instructs
  30           Proto not to look for a nested <code class="computeroutput">::type</code> within
  31           <code class="computeroutput">T</code> after type substitution.</p>
  32 </div>
  33 <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
  34 <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../../proto/reference.html#header.boost.proto.transform.make_hpp" title="Header &lt;boost/proto/transform/make.hpp&gt;">boost/proto/transform/make.hpp</a>&gt;
  35
  36 </span><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span>
  37 <span class="keyword">struct</span> <a class="link" href="noinvoke.html" title="Struct template noinvoke">noinvoke</a> <span class="special">{</span>
  38 <span class="special">}</span><span class="special">;</span></pre></div>
  39 <div class="refsect1">
  40 <a name="idp390978944"></a><h2>Description</h2>
  41 <p>
  42             <a class="link" href="../../ObjectTransform.html" title="Concept ObjectTransform">ObjectTransform</a>s are evaluated by
  43             <code class="computeroutput"><a class="link" href="make.html" title="Struct template make">proto::make&lt;&gt;</a></code>,
  44             which finds all nested transforms and replaces them with the result of their applications.
  45             If any substitutions are performed, the result is first assumed to be a metafunction to be applied;
  46             that is, Proto checks to see if the result has a nested <code class="computeroutput">::type</code>
  47             typedef. If it does, that becomes the result. The purpose of <code class="computeroutput">proto::noinvoke&lt;&gt;</code>
  48             is to prevent Proto from looking for a nested <code class="computeroutput">::type</code> typedef
  49             in these situations.
  50           </p>
  51 <p>
  52             Example:
  53             </p>
  54 <pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">Test</span>
  55   <span class="special">:</span> <a class="link" href="when.html" title="Struct template when">proto::when</a><span class="special">&lt;</span>
  56         <a class="link" href="_.html" title="Struct _">_</a>
  57       <span class="special">,</span> <span class="identifier">proto</span><span class="special">::</span><span class="identifier">noinvoke</span><span class="special">&lt;</span>
  58             <span class="comment">// This remove_pointer invocation is bloked by noinvoke</span>
  59             <span class="identifier">boost</span><span class="special">::</span><span class="identifier">remove_pointer</span><span class="special">&lt;</span>
  60                 <span class="comment">// This add_pointer invocation is *not* blocked by noinvoke</span>
  61                 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">add_pointer</span><span class="special">&lt;</span><a class="link" href="_.html" title="Struct _">_</a><span class="special">&gt;</span>
  62             <span class="special">&gt;</span>
  63         <span class="special">&gt;</span><span class="special">(</span><span class="special">)</span>
  64     <span class="special">&gt;</span>
  65 <span class="special">{</span><span class="special">}</span><span class="special">;</span>
  66
  67 <span class="keyword">void</span> <span class="identifier">test_noinvoke</span><span class="special">(</span><span class="special">)</span>
  68 <span class="special">{</span>
  69     <span class="keyword">typedef</span> <a class="link" href="terminal.html" title="Struct template terminal">proto::terminal</a><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span><span class="special">::</span><span class="identifier">type</span> <span class="identifier">Int</span><span class="special">;</span>
  70
  71     <span class="identifier">BOOST_MPL_ASSERT</span><span class="special">(</span><span class="special">(</span>
  72         <span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_same</span><span class="special">&lt;</span>
  73             <span class="identifier">boost</span><span class="special">::</span><span class="identifier">result_of</span><span class="special">&lt;</span><span class="identifier">Test</span><span class="special">(</span><span class="identifier">Int</span><span class="special">)</span><span class="special">&gt;</span><span class="special">::</span><span class="identifier">type</span>
  74           <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">remove_pointer</span><span class="special">&lt;</span><span class="identifier">Int</span> <span class="special">*</span><span class="special">&gt;</span>
  75         <span class="special">&gt;</span>
  76     <span class="special">)</span><span class="special">)</span><span class="special">;</span>
  77
  78     <span class="identifier">Int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="special">{</span><span class="number">42</span><span class="special">}</span><span class="special">;</span>
  79     <span class="identifier">boost</span><span class="special">::</span><span class="identifier">remove_pointer</span><span class="special">&lt;</span><span class="identifier">Int</span> <span class="special">*</span><span class="special">&gt;</span> <span class="identifier">t</span> <span class="special">=</span> <span class="identifier">Test</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><span class="identifier">i</span><span class="special">)</span><span class="special">;</span>
  80 <span class="special">}</span></pre>
  81 <p>
  82           </p>
  83 </div>
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  87 <td align="right"><div class="copyright-footer">Copyright &#169; 2008 Eric Niebler<p>
  88         Distributed under the Boost Software License, Version 1.0. (See accompanying
  89         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>)
  90       </p>
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