1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html> 3<head> 4<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 5<title>Struct template noinvoke</title> 6<link rel="stylesheet" href="../../../../doc/src/boostbook.css" type="text/css"> 7<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 8<link rel="home" href="../../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> 9<link rel="up" href="../../proto/reference.html#header.boost.proto.transform.make_hpp" title="Header <boost/proto/transform/make.hpp>"> 10<link rel="prev" href="lazy/impl.html" title="Struct template impl"> 11<link rel="next" href="protect.html" title="Struct template protect"> 12</head> 13<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 14<table cellpadding="2" width="100%"><tr> 15<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../boost.png"></td> 16<td align="center"><a href="../../../../index.html">Home</a></td> 17<td align="center"><a href="../../../../libs/libraries.htm">Libraries</a></td> 18<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 19<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 20<td align="center"><a href="../../../../more/index.htm">More</a></td> 21</tr></table> 22<hr> 23<div class="spirit-nav"> 24<a accesskey="p" href="lazy/impl.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../proto/reference.html#header.boost.proto.transform.make_hpp"><img src="../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="protect.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 25</div> 26<div class="refentry"> 27<a name="boost.proto.noinvoke"></a><div class="titlepage"></div> 28<div class="refnamediv"> 29<h2><span class="refentrytitle">Struct template noinvoke</span></h2> 30<p>boost::proto::noinvoke — A type annotation in an <a class="link" href="../../ObjectTransform.html" title="Concept ObjectTransform">ObjectTransform</a> which instructs 31 Proto not to look for a nested <code class="computeroutput">::type</code> within 32 <code class="computeroutput">T</code> after type substitution.</p> 33</div> 34<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> 35<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>> 36 37</span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> T<span class="special">></span> 38<span class="keyword">struct</span> <a class="link" href="noinvoke.html" title="Struct template noinvoke">noinvoke</a> <span class="special">{</span> 39<span class="special">}</span><span class="special">;</span></pre></div> 40<div class="refsect1"> 41<a name="id-1.3.33.5.52.4.4"></a><h2>Description</h2> 42<p> 43 <a class="link" href="../../ObjectTransform.html" title="Concept ObjectTransform">ObjectTransform</a>s are evaluated by 44 <code class="computeroutput"><a class="link" href="make.html" title="Struct template make">proto::make<></a></code>, 45 which finds all nested transforms and replaces them with the result of their applications. 46 If any substitutions are performed, the result is first assumed to be a metafunction to be applied; 47 that is, Proto checks to see if the result has a nested <code class="computeroutput">::type</code> 48 typedef. If it does, that becomes the result. The purpose of <code class="computeroutput">proto::noinvoke<></code> 49 is to prevent Proto from looking for a nested <code class="computeroutput">::type</code> typedef 50 in these situations. 51 </p> 52<p> 53 Example: 54 </p> 55<pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">Test</span> 56 <span class="special">:</span> <a class="link" href="when.html" title="Struct template when">proto::when</a><span class="special"><</span> 57 <a class="link" href="_.html" title="Struct _">_</a> 58 <span class="special">,</span> <span class="identifier">proto</span><span class="special">::</span><span class="identifier">noinvoke</span><span class="special"><</span> 59 <span class="comment">// This remove_pointer invocation is bloked by noinvoke</span> 60 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">remove_pointer</span><span class="special"><</span> 61 <span class="comment">// This add_pointer invocation is *not* blocked by noinvoke</span> 62 <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> 63 <span class="special">></span> 64 <span class="special">></span><span class="special">(</span><span class="special">)</span> 65 <span class="special">></span> 66<span class="special">{</span><span class="special">}</span><span class="special">;</span> 67 68<span class="keyword">void</span> <span class="identifier">test_noinvoke</span><span class="special">(</span><span class="special">)</span> 69<span class="special">{</span> 70 <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> 71 72 <span class="identifier">BOOST_MPL_ASSERT</span><span class="special">(</span><span class="special">(</span> 73 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_same</span><span class="special"><</span> 74 <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> 75 <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> 76 <span class="special">></span> 77 <span class="special">)</span><span class="special">)</span><span class="special">;</span> 78 79 <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> 80 <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> 81<span class="special">}</span></pre> 82<p> 83 </p> 84</div> 85</div> 86<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 87<td align="left"></td> 88<td align="right"><div class="copyright-footer">Copyright © 2008 Eric Niebler<p> 89 Distributed under the Boost Software License, Version 1.0. (See accompanying 90 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>) 91 </p> 92</div></td> 93</tr></table> 94<hr> 95<div class="spirit-nav"> 96<a accesskey="p" href="lazy/impl.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../proto/reference.html#header.boost.proto.transform.make_hpp"><img src="../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="protect.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 97</div> 98</body> 99</html> 100
