ceph/src/boost/libs/mpl/doc/refmanual/assert.html

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  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="./asserts.html" class="navigation-link">Asserts</a> / <a href="./assert.html" class="navigation-link">BOOST_MPL_ASSERT</a></td>
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  14 <div class="section" id="boost-mpl-assert">
  15 <h1><a class="toc-backref" href="./asserts.html#id1588">BOOST_MPL_ASSERT</a></h1>
  16 <div class="section" id="id1287">
  17 <h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3>
  18 <pre class="literal-block">
  19 #define <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>( pred ) \
  20     <em>unspecified token sequence</em> \
  21 /**/
  22 </pre>
  23 </div>
  24 <div class="section" id="id1288">
  25 <h3><a class="subsection-title" href="#description" name="description">Description</a></h3>
  26 <p>Generates a compilation error when the predicate <tt class="literal"><span class="pre">pred</span></tt> holds false.</p>
  27 </div>
  28 <div class="section" id="id1289">
  29 <h3><a class="subsection-title" href="#header" name="header">Header</a></h3>
  30 <pre class="literal-block">
  31 #include &lt;<a href="../../../../boost/mpl/assert.hpp" class="header">boost/mpl/assert.hpp</a>&gt;
  32 </pre>
  33 </div>
  34 <div class="section" id="id1290">
  35 <h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3>
  36 <table border="1" class="docutils table">
  37 <colgroup>
  38 <col width="19%" />
  39 <col width="43%" />
  40 <col width="38%" />
  41 </colgroup>
  42 <thead valign="bottom">
  43 <tr><th class="head">Parameter</th>
  44 <th class="head">Requirement</th>
  45 <th class="head">Description</th>
  46 </tr>
  47 </thead>
  48 <tbody valign="top">
  49 <tr><td><tt class="literal"><span class="pre">pred</span></tt></td>
  50 <td>Boolean nullary <a class="reference internal" href="./metafunction.html">Metafunction</a></td>
  51 <td>A predicate to be asserted.</td>
  52 </tr>
  53 </tbody>
  54 </table>
  55 </div>
  56 <div class="section" id="id1291">
  57 <h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3>
  58 <p>For any boolean nullary <a class="reference internal" href="./metafunction.html">Metafunction</a> <tt class="literal"><span class="pre">pred</span></tt>:</p>
  59 <pre class="literal-block">
  60 <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( pred ));
  61 </pre>
  62 <table class="docutils field-list" frame="void" rules="none">
  63 <col class="field-name" />
  64 <col class="field-body" />
  65 <tbody valign="top">
  66 <tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">None.</p>
  67 </td>
  68 </tr>
  69 <tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Generates a compilation error if <tt class="literal"><span class="pre">pred::type::value</span> <span class="pre">!=</span> <span class="pre">true</span></tt>, otherwise
  70 has no effect. Note that double parentheses are required even if no commas
  71 appear in the condition.</p>
  72 <p>When possible within the compiler's diagnostic capabilities,
  73 the error message will include the predicate's full type name, and have a
  74 general form of:</p>
  75 <pre class="last literal-block">
  76 <em>...</em> ************ pred::************ <em>...</em>
  77 </pre>
  78 </td>
  79 </tr>
  80 </tbody>
  81 </table>
  82 </div>
  83 <div class="section" id="id1292">
  84 <h3><a class="subsection-title" href="#example" name="example">Example</a></h3>
  85 <pre class="literal-block">
  86 template&lt; typename T, typename U &gt; struct my
  87 {
  88     // ...
  89     <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( is_same&lt; T,U &gt; ));
  90 };
  91
  92 my&lt;void*,char*&gt; test;
  93
  94 // In instantiation of `my&lt;void, char*&gt;':
  95 //   instantiated from here
  96 // conversion from `
  97 //   mpl_::failed************boost::is_same&lt;void, char*&gt;::************' to
  98 //   non-scalar type `mpl_::assert&lt;false&gt;' requested
  99 </pre>
 100 </div>
 101 <div class="section" id="id1293">
 102 <h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3>
 103 <p><a class="reference internal" href="./asserts.html">Asserts</a>, <a class="reference internal" href="./assert-not.html">BOOST_MPL_ASSERT_NOT</a>, <a class="reference internal" href="./assert-msg.html">BOOST_MPL_ASSERT_MSG</a>, <a class="reference internal" href="./assert-relation.html">BOOST_MPL_ASSERT_RELATION</a></p>
 104 <!-- Macros/Asserts//BOOST_MPL_ASSERT_MSG -->
 105 </div>
 106 </div>
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