1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Struct template valid_member_metafunction</title> 5<link rel="stylesheet" href="../../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../index.html" title="Chapter 1. The Type Traits Introspection Library"> 8<link rel="up" href="../../header/boost/tti/member_type_hpp.html" title="Header <boost/tti/member_type.hpp>"> 9<link rel="prev" href="../../header/boost/tti/member_type_hpp.html" title="Header <boost/tti/member_type.hpp>"> 10<link rel="next" href="valid_member_type.html" title="Struct template valid_member_type"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="../../header/boost/tti/member_type_hpp.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../header/boost/tti/member_type_hpp.html"><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="valid_member_type.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="refentry"> 26<a name="boost.tti.valid_member_metafunction"></a><div class="titlepage"></div> 27<div class="refnamediv"> 28<h2><span class="refentrytitle">Struct template valid_member_metafunction</span></h2> 29<p>boost::tti::valid_member_metafunction — A metafunction which checks whether the invoked macro metafunction generated by BOOST_TTI_MEMBER_TYPE ( BOOST_TTI_TRAIT_MEMBER_TYPE ) hold a valid type. </p> 30</div> 31<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> 32<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="../../header/boost/tti/member_type_hpp.html" title="Header <boost/tti/member_type.hpp>">boost/tti/member_type.hpp</a>> 33 34</span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> BOOST_TTI_METAFUNCTION<span class="special">></span> 35<span class="keyword">struct</span> <a class="link" href="valid_member_metafunction.html" title="Struct template valid_member_metafunction">valid_member_metafunction</a> <span class="special">:</span> <span class="keyword">public</span> boost::mpl::not_< boost::is_same< BOOST_TTI_METAFUNCTION::type, BOOST_TTI_METAFUNCTION::boost_tti_marker_type > > 36<span class="special">{</span> 37<span class="special">}</span><span class="special">;</span></pre></div> 38<div class="refsect1"> 39<a name="idm45658022112592"></a><h2>Description</h2> 40<p>The metafunction '<a class="link" href="valid_member_metafunction.html" title="Struct template valid_member_metafunction">valid_member_metafunction</a>', which is in the boost::tti namespace, takes the form of:</p> 41<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">BOOST_TTI_METAFUNCTION</span><span class="special">></span> 42<span class="keyword">struct</span> <span class="identifier">valid_member_metafunction</span> 43 <span class="special">{</span> 44 <span class="keyword">static</span> <span class="keyword">const</span> <span class="identifier">value</span> <span class="special">=</span> <span class="identifier">unspecified</span><span class="special">;</span> 45 <span class="keyword">typedef</span> <span class="identifier">mpl</span><span class="special">::</span><span class="identifier">bool_</span><span class="special"><</span><span class="keyword">true</span><span class="special">-</span><span class="identifier">or</span><span class="special">-</span><span class="keyword">false</span><span class="special">></span> <span class="identifier">type</span><span class="special">;</span> 46 <span class="special">}</span><span class="special">;</span> 47 48<span class="identifier">The</span> <span class="identifier">metafunction</span> <span class="identifier">types</span> <span class="identifier">and</span> <span class="keyword">return</span><span class="special">:</span> 49 50 <span class="identifier">BOOST_TTI_METAFUNCTION</span> <span class="special">=</span> <span class="identifier">The</span> <span class="identifier">invoked</span> <span class="identifier">macro</span> <span class="identifier">metafunction</span> <span class="identifier">generated</span> <span class="identifier">by</span> <span class="identifier">BOOST_TTI_MEMBER_TYPE</span> <span class="special">(</span> <span class="identifier">BOOST_TTI_TRAIT_MEMBER_TYPE</span> <span class="special">)</span><span class="special">.</span> 51 52 <span class="identifier">returns</span> <span class="special">=</span> <span class="char">'value'</span> <span class="identifier">is</span> <span class="keyword">true</span> <span class="keyword">if</span> <span class="identifier">the</span> <span class="identifier">nested</span> <span class="identifier">type</span> <span class="identifier">of</span> <span class="identifier">the</span> <span class="identifier">invoked</span> <span class="identifier">metafunction</span> <span class="identifier">is</span> <span class="identifier">valid</span><span class="special">,</span> <span class="identifier">otherwise</span> <span class="char">'value'</span> <span class="identifier">is</span> <span class="keyword">false</span><span class="special">.</span> 53 <span class="identifier">A</span> <span class="identifier">valid</span> <span class="identifier">type</span> <span class="identifier">means</span> <span class="identifier">that</span> <span class="identifier">the</span> <span class="identifier">invoked</span> <span class="identifier">metafunction</span><span class="char">'s inner '</span><span class="identifier">type</span><span class="char">' is not the marker type. 54</span></pre> 55<p> </p> 56</div> 57</div> 58<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 59<td align="left"></td> 60<td align="right"><div class="copyright-footer">Copyright © 2011-2013 Tropic Software 61 East Inc<p> 62 Distributed under the Boost Software License, Version 1.0. (See accompanying 63 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>) 64 </p> 65</div></td> 66</tr></table> 67<hr> 68<div class="spirit-nav"> 69<a accesskey="p" href="../../header/boost/tti/member_type_hpp.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../header/boost/tti/member_type_hpp.html"><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="valid_member_type.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 70</div> 71</body> 72</html> 73
