ceph/src/boost/libs/mpl/doc/refmanual/has-xxx-trait-def.html

   1 <?xml version="1.0" encoding="utf-8" ?>
   2 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
   3 <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
   4 <head>
   5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
   6 <meta name="generator" content="Docutils 0.7: http://docutils.sourceforge.net/" />
   7 <title>The MPL Reference Manual: BOOST_MPL_HAS_XXX_TRAIT_DEF</title>
   8 <link rel="stylesheet" href="../style.css" type="text/css" />
   9 </head>
  10 <body class="docframe refmanual">
  11 <table class="header"><tr class="header"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./has-xxx-template-named-def.html" class="navigation-link">Prev</a>&nbsp;<a href="./has-xxx-trait-named-def.html" class="navigation-link">Next</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./has-xxx-template-named-def.html" class="navigation-link">Back</a>&nbsp;<a href="./has-xxx-trait-named-def.html" class="navigation-link">Along</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./introspection.html" class="navigation-link">Up</a>&nbsp;<a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td>
  12 <td class="header-group page-location"><a href="../refmanual.html" class="navigation-link">Front Page</a> / <a href="./macros.html" class="navigation-link">Macros</a> / <a href="./introspection.html" class="navigation-link">Introspection</a> / <a href="./has-xxx-trait-def.html" class="navigation-link">BOOST_MPL_HAS_XXX_TRAIT_DEF</a></td>
  13 </tr></table><div class="header-separator"></div>
  14 <div class="section" id="boost-mpl-has-xxx-trait-def">
  15 <h1><a class="toc-backref" href="./introspection.html#id1595">BOOST_MPL_HAS_XXX_TRAIT_DEF</a></h1>
  16 <div class="section" id="id1329">
  17 <h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3>
  18 <pre class="literal-block">
  19 #define <a href="./has-xxx-trait-def.html" class="identifier">BOOST_MPL_HAS_XXX_TRAIT_DEF</a>(name) \
  20     <em>unspecified token sequence</em> \
  21 /**/
  22 </pre>
  23 </div>
  24 <div class="section" id="id1330">
  25 <h3><a class="subsection-title" href="#description" name="description">Description</a></h3>
  26 <p>Expands into a definition of a boolean unary <a class="reference internal" href="./metafunction.html">Metafunction</a> <tt class="literal"><span class="pre">has_name</span></tt>
  27 such that for any type <tt class="literal"><span class="pre">x</span></tt> <tt class="literal"><span class="pre">has_name&lt;x&gt;::value</span> <span class="pre">==</span> <span class="pre">true</span></tt> if and only
  28 if <tt class="literal"><span class="pre">x</span></tt> is a class type and has a nested type memeber <tt class="literal"><span class="pre">x::name</span></tt>.</p>
  29 <p>On the deficient compilers not capabale of performing the detection,
  30 <tt class="literal"><span class="pre">has_name&lt;x&gt;::value</span></tt> always returns <tt class="literal"><span class="pre">false</span></tt>. A boolean configuraion
  31 macro, <a class="reference internal" href="./cfg-no-has-xxx.html">BOOST_MPL_CFG_NO_HAS_XXX</a>, is provided to signal or override
  32 the &quot;deficient&quot; status of a particular compiler.</p>
  33 <p>[<em>Note:</em> <a class="reference internal" href="./has-xxx-trait-def.html">BOOST_MPL_HAS_XXX_TRAIT_DEF</a> is a simplified front end to
  34 the <a class="reference internal" href="./has-xxx-trait-named-def.html">BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF</a> introspection macro — <em>end note</em>]</p>
  35 </div>
  36 <div class="section" id="id1331">
  37 <h3><a class="subsection-title" href="#header" name="header">Header</a></h3>
  38 <pre class="literal-block">
  39 #include &lt;<a href="../../../../boost/mpl/has_xxx.hpp" class="header">boost/mpl/has_xxx.hpp</a>&gt;
  40 </pre>
  41 </div>
  42 <div class="section" id="id1332">
  43 <h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3>
  44 <table border="1" class="docutils table">
  45 <colgroup>
  46 <col width="15%" />
  47 <col width="32%" />
  48 <col width="53%" />
  49 </colgroup>
  50 <thead valign="bottom">
  51 <tr><th class="head">Parameter</th>
  52 <th class="head">Requirement</th>
  53 <th class="head">Description</th>
  54 </tr>
  55 </thead>
  56 <tbody valign="top">
  57 <tr><td><tt class="literal"><span class="pre">name</span></tt></td>
  58 <td>A legal identifier token</td>
  59 <td>A name of the member being detected.</td>
  60 </tr>
  61 </tbody>
  62 </table>
  63 </div>
  64 <div class="section" id="id1333">
  65 <h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3>
  66 <p>For any legal C++ identifier <tt class="literal"><span class="pre">name</span></tt>:</p>
  67 <pre class="literal-block">
  68 <a href="./has-xxx-trait-def.html" class="identifier">BOOST_MPL_HAS_XXX_TRAIT_DEF</a>(name)
  69 </pre>
  70 <table class="docutils field-list" frame="void" rules="none">
  71 <col class="field-name" />
  72 <col class="field-body" />
  73 <tbody valign="top">
  74 <tr class="field"><th class="field-name">Precondition:</th><td class="field-body"><p class="first">Appears at namespace scope.</p>
  75 </td>
  76 </tr>
  77 <tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">None.</p>
  78 </td>
  79 </tr>
  80 <tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Equivalent to</p>
  81 <pre class="last literal-block">
  82 <a href="./has-xxx-trait-named-def.html" class="identifier">BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF</a>(
  83       BOOST_PP_CAT(has_,name), name, false
  84     )
  85 </pre>
  86 </td>
  87 </tr>
  88 </tbody>
  89 </table>
  90 </div>
  91 <div class="section" id="id1334">
  92 <h3><a class="subsection-title" href="#example" name="example">Example</a></h3>
  93 <pre class="literal-block">
  94 <a href="./has-xxx-trait-def.html" class="identifier">BOOST_MPL_HAS_XXX_TRAIT_DEF</a>(xxx)
  95
  96 struct test1 {};
  97 struct test2 { void xxx(); };
  98 struct test3 { int xxx; };
  99 struct test4 { static int xxx(); };
 100 struct test5 { template&lt; typename T &gt; struct xxx {}; };
 101 struct test6 { typedef int xxx; };
 102 struct test7 { struct xxx; };
 103 struct test8 { typedef void (*xxx)(); };
 104 struct test9 { typedef void (xxx)(); };
 105
 106 <a href="./assert-not.html" class="identifier">BOOST_MPL_ASSERT_NOT</a>(( has_xxx&lt;test1&gt; ));
 107 <a href="./assert-not.html" class="identifier">BOOST_MPL_ASSERT_NOT</a>(( has_xxx&lt;test2&gt; ));
 108 <a href="./assert-not.html" class="identifier">BOOST_MPL_ASSERT_NOT</a>(( has_xxx&lt;test3&gt; ));
 109 <a href="./assert-not.html" class="identifier">BOOST_MPL_ASSERT_NOT</a>(( has_xxx&lt;test4&gt; ));
 110 <a href="./assert-not.html" class="identifier">BOOST_MPL_ASSERT_NOT</a>(( has_xxx&lt;test5&gt; ));
 111
 112 #if !defined(<a href="./cfg-no-has-xxx.html" class="identifier">BOOST_MPL_CFG_NO_HAS_XXX</a>)
 113 <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( has_xxx&lt;test6&gt; ));
 114 <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( has_xxx&lt;test7&gt; ));
 115 <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( has_xxx&lt;test8&gt; ));
 116 <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( has_xxx&lt;test9&gt; ));
 117 #endif
 118
 119 <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( has_xxx&lt;test6,<a href="./bool.html" class="identifier">true_</a>&gt; ));
 120 <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( has_xxx&lt;test7,<a href="./bool.html" class="identifier">true_</a>&gt; ));
 121 <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( has_xxx&lt;test8,<a href="./bool.html" class="identifier">true_</a>&gt; ));
 122 <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( has_xxx&lt;test9,<a href="./bool.html" class="identifier">true_</a>&gt; ));
 123 </pre>
 124 </div>
 125 <div class="section" id="id1335">
 126 <h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3>
 127 <p><a class="reference internal" href="./macros.html">Macros</a>, <a class="reference internal" href="./has-xxx-trait-named-def.html">BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF</a>, <a class="reference internal" href="./cfg-no-has-xxx.html">BOOST_MPL_CFG_NO_HAS_XXX</a></p>
 128 <!-- Macros/Introspection//BOOST_MPL_HAS_XXX_TRAIT_NAMED_DEF -->
 129 </div>
 130 </div>
 131
 132 <div class="footer-separator"></div>
 133 <table class="footer"><tr class="footer"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./has-xxx-template-named-def.html" class="navigation-link">Prev</a>&nbsp;<a href="./has-xxx-trait-named-def.html" class="navigation-link">Next</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./has-xxx-template-named-def.html" class="navigation-link">Back</a>&nbsp;<a href="./has-xxx-trait-named-def.html" class="navigation-link">Along</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./introspection.html" class="navigation-link">Up</a>&nbsp;<a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td>
 134 <td><div class="copyright-footer"><div class="copyright">Copyright ©  2001-2009 Aleksey Gurtovoy and David Abrahams</div>
 135 Distributed under the Boost Software License, Version 1.0. (See accompanying
 136 file LICENSE_1_0.txt or copy at <a class="reference external" href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)</div></td></tr></table></body>
 137 </html>