ceph/src/boost/libs/type_traits/doc/html/boost_typetraits/category/value_traits/primary.html

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  26 <div class="titlepage"><div><div><h4 class="title">
  27 <a name="boost_typetraits.category.value_traits.primary"></a><a class="link" href="primary.html" title="Categorizing a Type">Categorizing
  28         a Type</a>
  29 </h4></div></div></div>
  30 <p>
  31           These traits identify what "kind" of type some type <code class="computeroutput"><span class="identifier">T</span></code> is. These are split into two groups:
  32           primary traits which are all mutually exclusive, and composite traits that
  33           are compositions of one or more primary traits.
  34         </p>
  35 <p>
  36           For any given type, exactly one primary type trait will inherit from <a class="link" href="../../reference/integral_constant.html" title="integral_constant">true_type</a>,
  37           and all the others will inherit from <a class="link" href="../../reference/integral_constant.html" title="integral_constant">false_type</a>,
  38           in other words these traits are mutually exclusive.
  39         </p>
  40 <p>
  41           This means that <code class="computeroutput"><a class="link" href="../../reference/is_integral.html" title="is_integral">is_integral</a><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">value</span></code>
  42           and <code class="computeroutput"><a class="link" href="../../reference/is_floating_point.html" title="is_floating_point">is_floating_point</a><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">value</span></code>
  43           will only ever be true for built-in types; if you want to check for a user-defined
  44           class type that behaves "as if" it is an integral or floating
  45           point type, then use the <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">numeric_limits</span>
  46           <span class="keyword">template</span></code> instead.
  47         </p>
  48 <p>
  49           <span class="bold"><strong>Synopsis:</strong></span>
  50         </p>
  51 <pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
  52 <span class="keyword">struct</span> <a class="link" href="../../reference/is_array.html" title="is_array">is_array</a><span class="special">;</span>
  53
  54 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
  55 <span class="keyword">struct</span> <a class="link" href="../../reference/is_class.html" title="is_class">is_class</a><span class="special">;</span>
  56
  57 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
  58 <span class="keyword">struct</span> <a class="link" href="../../reference/is_complex.html" title="is_complex">is_complex</a><span class="special">;</span>
  59
  60 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
  61 <span class="keyword">struct</span> <a class="link" href="../../reference/is_enum.html" title="is_enum">is_enum</a><span class="special">;</span>
  62
  63 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
  64 <span class="keyword">struct</span> <a class="link" href="../../reference/is_floating_point.html" title="is_floating_point">is_floating_point</a><span class="special">;</span>
  65
  66 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
  67 <span class="keyword">struct</span> <a class="link" href="../../reference/is_function.html" title="is_function">is_function</a><span class="special">;</span>
  68
  69 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
  70 <span class="keyword">struct</span> <a class="link" href="../../reference/is_integral.html" title="is_integral">is_integral</a><span class="special">;</span>
  71
  72 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
  73 <span class="keyword">struct</span> <a class="link" href="../../reference/is_member_function_pointer.html" title="is_member_function_pointer">is_member_function_pointer</a><span class="special">;</span>
  74
  75 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
  76 <span class="keyword">struct</span> <a class="link" href="../../reference/is_member_object_pointer.html" title="is_member_object_pointer">is_member_object_pointer</a><span class="special">;</span>
  77
  78 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
  79 <span class="keyword">struct</span> <a class="link" href="../../reference/is_pointer.html" title="is_pointer">is_pointer</a><span class="special">;</span>
  80
  81 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
  82 <span class="keyword">struct</span> <a class="link" href="../../reference/is_lvalue_reference.html" title="is_lvalue_reference">is_lvalue_reference</a><span class="special">;</span>
  83
  84 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
  85 <span class="keyword">struct</span> <a class="link" href="../../reference/is_rvalue_reference.html" title="is_rvalue_reference">is_rvalue_reference</a><span class="special">;</span>
  86
  87 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
  88 <span class="keyword">struct</span> <a class="link" href="../../reference/is_union.html" title="is_union">is_union</a><span class="special">;</span>
  89
  90 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
  91 <span class="keyword">struct</span> <a class="link" href="../../reference/is_void.html" title="is_void">is_void</a><span class="special">;</span>
  92 </pre>
  93 <p>
  94           The following traits are made up of the union of one or more type categorizations.
  95           A type may belong to more than one of these categories, in addition to
  96           one of the primary categories.
  97         </p>
  98 <pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
  99 <span class="keyword">struct</span> <a class="link" href="../../reference/is_arithmetic.html" title="is_arithmetic">is_arithmetic</a><span class="special">;</span>
 100
 101 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
 102 <span class="keyword">struct</span> <a class="link" href="../../reference/is_compound.html" title="is_compound">is_compound</a><span class="special">;</span>
 103
 104 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
 105 <span class="keyword">struct</span> <a class="link" href="../../reference/is_fundamental.html" title="is_fundamental">is_fundamental</a><span class="special">;</span>
 106
 107 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
 108 <span class="keyword">struct</span> <a class="link" href="../../reference/is_member_pointer.html" title="is_member_pointer">is_member_pointer</a><span class="special">;</span>
 109
 110 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
 111 <span class="keyword">struct</span> <a class="link" href="../../reference/is_object.html" title="is_object">is_object</a><span class="special">;</span>
 112
 113 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
 114 <span class="keyword">struct</span> <a class="link" href="../../reference/is_reference.html" title="is_reference">is_reference</a><span class="special">;</span>
 115
 116 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
 117 <span class="keyword">struct</span> <a class="link" href="../../reference/is_scalar.html" title="is_scalar">is_scalar</a><span class="special">;</span>
 118 </pre>
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 122 <td align="right"><div class="copyright-footer">Copyright &#169; 2000, 2011 Adobe Systems Inc, David Abrahams,
 123       Frederic Bron, Steve Cleary, Beman Dawes, Aleksey Gurtovoy, Howard Hinnant,
 124       Jesse Jones, Mat Marcus, Itay Maman, John Maddock, Alexander Nasonov, Thorsten
 125       Ottosen, Roman Perepelitsa, Robert Ramey, Jeremy Siek, Robert Stewart and Steven
 126       Watanabe<p>
 127         Distributed under the Boost Software License, Version 1.0. (See accompanying
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