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<a name="boost.proto.noinvoke"></a><div class="titlepage"></div>
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<h2><span class="refentrytitle">Struct template noinvoke</span></h2>
<p>boost::proto::noinvoke — A type annotation in an <a class="link" href="../../ObjectTransform.html" title="Concept ObjectTransform">ObjectTransform</a> which instructs
Proto not to look for a nested <code class="computeroutput">::type</code> within
<code class="computeroutput">T</code> after type substitution.</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.make_hpp" title="Header <boost/proto/transform/make.hpp>">boost/proto/transform/make.hpp</a>>
</span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> T<span class="special">></span>
<span class="keyword">struct</span> <a class="link" href="noinvoke.html" title="Struct template noinvoke">noinvoke</a> <span class="special">{</span>
<span class="special">}</span><span class="special">;</span></pre></div>
<div class="refsect1">
<a name="idm45555170628000"></a><h2>Description</h2>
<p>
<a class="link" href="../../ObjectTransform.html" title="Concept ObjectTransform">ObjectTransform</a>s are evaluated by
<code class="computeroutput"><a class="link" href="make.html" title="Struct template make">proto::make<></a></code>,
which finds all nested transforms and replaces them with the result of their applications.
If any substitutions are performed, the result is first assumed to be a metafunction to be applied;
that is, Proto checks to see if the result has a nested <code class="computeroutput">::type</code>
typedef. If it does, that becomes the result. The purpose of <code class="computeroutput">proto::noinvoke<></code>
is to prevent Proto from looking for a nested <code class="computeroutput">::type</code> typedef
in these situations.
</p>
<p>
Example:
</p>
<pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">Test</span>
<span class="special">:</span> <a class="link" href="when.html" title="Struct template when">proto::when</a><span class="special"><</span>
<a class="link" href="_.html" title="Struct _">_</a>
<span class="special">,</span> <span class="identifier">proto</span><span class="special">::</span><span class="identifier">noinvoke</span><span class="special"><</span>
<span class="comment">// This remove_pointer invocation is bloked by noinvoke</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">remove_pointer</span><span class="special"><</span>
<span class="comment">// This add_pointer invocation is *not* blocked by noinvoke</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">add_pointer</span><span class="special"><</span><a class="link" href="_.html" title="Struct _">_</a><span class="special">></span>
<span class="special">></span>
<span class="special">></span><span class="special">(</span><span class="special">)</span>
<span class="special">></span>
<span class="special">{</span><span class="special">}</span><span class="special">;</span>
<span class="keyword">void</span> <span class="identifier">test_noinvoke</span><span class="special">(</span><span class="special">)</span>
<span class="special">{</span>
<span class="keyword">typedef</span> <a class="link" href="terminal.html" title="Struct template terminal">proto::terminal</a><span class="special"><</span><span class="keyword">int</span><span class="special">></span><span class="special">::</span><span class="identifier">type</span> <span class="identifier">Int</span><span class="special">;</span>
<span class="identifier">BOOST_MPL_ASSERT</span><span class="special">(</span><span class="special">(</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_same</span><span class="special"><</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">result_of</span><span class="special"><</span><span class="identifier">Test</span><span class="special">(</span><span class="identifier">Int</span><span class="special">)</span><span class="special">></span><span class="special">::</span><span class="identifier">type</span>
<span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">remove_pointer</span><span class="special"><</span><span class="identifier">Int</span> <span class="special">*</span><span class="special">></span>
<span class="special">></span>
<span class="special">)</span><span class="special">)</span><span class="special">;</span>
<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>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">remove_pointer</span><span class="special"><</span><span class="identifier">Int</span> <span class="special">*</span><span class="special">></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>
<span class="special">}</span></pre>
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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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