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

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  14 <div class="section" id="boost-mpl-assert-relation">
  15 <h1><a class="toc-backref" href="./asserts.html#id1591">BOOST_MPL_ASSERT_RELATION</a></h1>
  16 <div class="section" id="id1308">
  17 <h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3>
  18 <pre class="literal-block">
  19 #define <a href="./assert-relation.html" class="identifier">BOOST_MPL_ASSERT_RELATION</a>( x, relation, y ) \
  20     <em>unspecified token sequence</em> \
  21 /**/
  22 </pre>
  23 </div>
  24 <div class="section" id="id1309">
  25 <h3><a class="subsection-title" href="#description" name="description">Description</a></h3>
  26 <p>A specialized assertion macro for checking numerical conditions. Generates
  27 a compilation error when the condition <tt class="literal"><span class="pre">(</span> <span class="pre">x</span> <span class="pre">relation</span> <span class="pre">y</span> <span class="pre">)</span></tt>
  28 doesn't hold.</p>
  29 </div>
  30 <div class="section" id="id1310">
  31 <h3><a class="subsection-title" href="#header" name="header">Header</a></h3>
  32 <pre class="literal-block">
  33 #include &lt;<a href="../../../../boost/mpl/assert.hpp" class="header">boost/mpl/assert.hpp</a>&gt;
  34 </pre>
  35 </div>
  36 <div class="section" id="id1311">
  37 <h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3>
  38 <table border="1" class="docutils table">
  39 <colgroup>
  40 <col width="15%" />
  41 <col width="36%" />
  42 <col width="48%" />
  43 </colgroup>
  44 <thead valign="bottom">
  45 <tr><th class="head">Parameter</th>
  46 <th class="head">Requirement</th>
  47 <th class="head">Description</th>
  48 </tr>
  49 </thead>
  50 <tbody valign="top">
  51 <tr><td><tt class="literal"><span class="pre">x</span></tt></td>
  52 <td>An integral constant</td>
  53 <td>Left operand of the checked relation.</td>
  54 </tr>
  55 <tr><td><tt class="literal"><span class="pre">y</span></tt></td>
  56 <td>An integral constant</td>
  57 <td>Right operand of the checked relation.</td>
  58 </tr>
  59 <tr><td><tt class="literal"><span class="pre">relation</span></tt></td>
  60 <td>A C++ operator token</td>
  61 <td>An operator token for the relation being
  62 checked.</td>
  63 </tr>
  64 </tbody>
  65 </table>
  66 </div>
  67 <div class="section" id="id1312">
  68 <h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3>
  69 <p>For any integral constants <tt class="literal"><span class="pre">x</span></tt>, <tt class="literal"><span class="pre">y</span></tt> and a legal C++ operator token <tt class="literal"><span class="pre">op</span></tt>:</p>
  70 <pre class="literal-block">
  71 <a href="./assert-relation.html" class="identifier">BOOST_MPL_ASSERT_RELATION</a>( x, op, y );
  72 </pre>
  73 <table class="docutils field-list" frame="void" rules="none">
  74 <col class="field-name" />
  75 <col class="field-body" />
  76 <tbody valign="top">
  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">Generates a compilation error if <tt class="literal"><span class="pre">(</span> <span class="pre">x</span> <span class="pre">op</span> <span class="pre">y</span> <span class="pre">)</span> <span class="pre">!=</span> <span class="pre">true</span></tt>, otherwise
  81 has no effect.</p>
  82 <p>When possible within the compiler's diagnostic capabilities,
  83 the error message will include a name of the relation being checked,
  84 the actual values of both operands, and have a general form of:</p>
  85 <pre class="last literal-block">
  86 <em>...</em> ************<em>...</em>assert_relation&lt;op, x, y&gt;::************) <em>...</em>
  87 </pre>
  88 </td>
  89 </tr>
  90 </tbody>
  91 </table>
  92 </div>
  93 <div class="section" id="id1313">
  94 <h3><a class="subsection-title" href="#example" name="example">Example</a></h3>
  95 <pre class="literal-block">
  96 template&lt; typename T, typename U &gt; struct my
  97 {
  98     // ...
  99     <a href="./assert-relation.html" class="identifier">BOOST_MPL_ASSERT_RELATION</a>( sizeof(T), &lt;, sizeof(U) );
 100 };
 101
 102 my&lt;char[50],char[10]&gt; test;
 103
 104 // In instantiation of `my&lt;char[50], char[10]&gt;':
 105 //   instantiated from here
 106 // conversion from `
 107 //   mpl_::failed************mpl_::assert_relation&lt;<a href="./less.html" class="identifier">less</a>, 50, 10&gt;::************'
 108 //   to non-scalar type `mpl_::assert&lt;false&gt;' requested
 109 </pre>
 110 </div>
 111 <div class="section" id="id1314">
 112 <h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3>
 113 <p><a class="reference internal" href="./asserts.html">Asserts</a>, <a class="reference internal" href="./assert.html">BOOST_MPL_ASSERT</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></p>
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