ceph/src/boost/libs/numeric/conversion/doc/html/boost_numericconversion/type_requirements_and_user_defined_types_support.html

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  24 </div>
  25 <div class="section">
  26 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
  27 <a name="boost_numericconversion.type_requirements_and_user_defined_types_support"></a><a class="link" href="type_requirements_and_user_defined_types_support.html" title="Type Requirements and User-defined-types support">Type
  28     Requirements and User-defined-types support</a>
  29 </h2></div></div></div>
  30 <div class="toc"><dl class="toc">
  31 <dt><span class="section"><a href="type_requirements_and_user_defined_types_support.html#boost_numericconversion.type_requirements_and_user_defined_types_support.type_requirements">Type
  32       Requirements</a></span></dt>
  33 <dt><span class="section"><a href="type_requirements_and_user_defined_types_support.html#boost_numericconversion.type_requirements_and_user_defined_types_support.udt_s_special_semantics">UDT's
  34       special semantics</a></span></dt>
  35 <dt><span class="section"><a href="type_requirements_and_user_defined_types_support.html#boost_numericconversion.type_requirements_and_user_defined_types_support.special_policies">Special
  36       Policies</a></span></dt>
  37 <dt><span class="section"><a href="type_requirements_and_user_defined_types_support.html#boost_numericconversion.type_requirements_and_user_defined_types_support.udts_with_numeric_cast">UDTs
  38       with numeric_cast</a></span></dt>
  39 </dl></div>
  40 <div class="section">
  41 <div class="titlepage"><div><div><h3 class="title">
  42 <a name="boost_numericconversion.type_requirements_and_user_defined_types_support.type_requirements"></a><a class="link" href="type_requirements_and_user_defined_types_support.html#boost_numericconversion.type_requirements_and_user_defined_types_support.type_requirements" title="Type Requirements">Type
  43       Requirements</a>
  44 </h3></div></div></div>
  45 <p>
  46         Both arithmetic (built-in) and user-defined numeric types require proper
  47         specialization of <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">numeric_limits</span><span class="special">&lt;&gt;</span></code>
  48         (that is, with (in-class) integral constants).
  49       </p>
  50 <p>
  51         The library uses <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">numeric_limits</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">is_specialized</span></code> to detect whether the type
  52         is builtin or user defined, and <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">numeric_limits</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">is_integer</span></code>, <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">numeric_limits</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">is_signed</span></code> to detect whether the type is
  53         integer or floating point; and whether it is signed/unsigned.
  54       </p>
  55 <p>
  56         The default <code class="computeroutput"><span class="identifier">Float2IntRounder</span></code>
  57         policies uses unqualified calls to functions <code class="computeroutput"><span class="identifier">floor</span><span class="special">()</span></code> and <code class="computeroutput"><span class="identifier">ceil</span><span class="special">()</span></code>; but the standard functions are introduced
  58         in scope by a using directive:
  59       </p>
  60 <pre class="programlisting"><span class="keyword">using</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">floor</span> <span class="special">;</span> <span class="keyword">return</span> <span class="identifier">floor</span><span class="special">(</span><span class="identifier">s</span><span class="special">);</span>
  61 </pre>
  62 <p>
  63         Therefore, for builtin arithmetic types, the std functions will be used.
  64         User defined types should provide overloaded versions of these functions
  65         in order to use the default rounder policies. If these overloads are defined
  66         within a user namespace argument dependent lookup (ADL) should find them,
  67         but if your compiler has a weak ADL you might need to put these functions
  68         some place else or write your own rounder policy.
  69       </p>
  70 <p>
  71         The default <code class="computeroutput"><span class="identifier">Trunc</span><span class="special">&lt;&gt;</span></code>
  72         rounder policy needs to determine if the source value is positive or not,
  73         and for this it evaluates the expression <code class="computeroutput"><span class="identifier">s</span>
  74         <span class="special">&lt;</span> <span class="keyword">static_cast</span><span class="special">&lt;</span><span class="identifier">S</span><span class="special">&gt;(</span><span class="number">0</span><span class="special">)</span></code>. Therefore,
  75         user defined types require a visible <code class="computeroutput"><span class="keyword">operator</span><span class="special">&lt;</span></code> in order to use the <code class="computeroutput"><span class="identifier">Trunc</span><span class="special">&lt;&gt;</span></code> policy (the default).
  76       </p>
  77 </div>
  78 <div class="section">
  79 <div class="titlepage"><div><div><h3 class="title">
  80 <a name="boost_numericconversion.type_requirements_and_user_defined_types_support.udt_s_special_semantics"></a><a class="link" href="type_requirements_and_user_defined_types_support.html#boost_numericconversion.type_requirements_and_user_defined_types_support.udt_s_special_semantics" title="UDT's special semantics">UDT's
  81       special semantics</a>
  82 </h3></div></div></div>
  83 <h5>
  84 <a name="boost_numericconversion.type_requirements_and_user_defined_types_support.udt_s_special_semantics.h0"></a>
  85         <span class="phrase"><a name="boost_numericconversion.type_requirements_and_user_defined_types_support.udt_s_special_semantics.conversion_traits"></a></span><a class="link" href="type_requirements_and_user_defined_types_support.html#boost_numericconversion.type_requirements_and_user_defined_types_support.udt_s_special_semantics.conversion_traits">Conversion
  86         Traits</a>
  87       </h5>
  88 <p>
  89         If a User Defined Type is involved in a conversion, it is <span class="emphasis"><em>assumed</em></span>
  90         that the UDT has <a class="link" href="definitions.html#boost_numericconversion.definitions.range_and_precision" title="Range and Precision">wider
  91         range</a> than any built-in type, and consequently the values of some
  92         <code class="computeroutput"><span class="identifier">converter_traits</span><span class="special">&lt;&gt;</span></code>
  93         members are hardwired regardless of the reality. The following table summarizes
  94         this:
  95       </p>
  96 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
  97 <li class="listitem">
  98             <code class="computeroutput"><span class="identifier">Target</span><span class="special">=</span></code><span class="emphasis"><em>UDT</em></span>
  99             and <code class="computeroutput"><span class="identifier">Source</span><span class="special">=</span></code><span class="emphasis"><em>built-in</em></span>
 100             <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; ">
 101 <li class="listitem">
 102                   <code class="computeroutput"><span class="identifier">subranged</span><span class="special">=</span><span class="keyword">false</span></code>
 103                 </li>
 104 <li class="listitem">
 105                   <code class="computeroutput"><span class="identifier">supertype</span><span class="special">=</span><span class="identifier">Target</span></code>
 106                 </li>
 107 <li class="listitem">
 108                   <code class="computeroutput"><span class="identifier">subtype</span><span class="special">=</span><span class="identifier">Source</span></code>
 109                 </li>
 110 </ul></div>
 111           </li>
 112 <li class="listitem">
 113             <code class="computeroutput"><span class="identifier">Target</span><span class="special">=</span></code><span class="emphasis"><em>built-in</em></span>
 114             and <code class="computeroutput"><span class="identifier">Source</span><span class="special">=</span></code><span class="emphasis"><em>UDT</em></span>
 115             <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; ">
 116 <li class="listitem">
 117                   <code class="computeroutput"><span class="identifier">subranged</span><span class="special">=</span><span class="keyword">true</span></code>
 118                 </li>
 119 <li class="listitem">
 120                   <code class="computeroutput"><span class="identifier">supertype</span><span class="special">=</span><span class="identifier">Source</span></code>
 121                 </li>
 122 <li class="listitem">
 123                   <code class="computeroutput"><span class="identifier">subtype</span><span class="special">=</span><span class="identifier">Target</span></code>
 124                 </li>
 125 </ul></div>
 126           </li>
 127 <li class="listitem">
 128             <code class="computeroutput"><span class="identifier">Target</span><span class="special">=</span></code><span class="emphasis"><em>UDT</em></span>
 129             and <code class="computeroutput"><span class="identifier">Source</span><span class="special">=</span></code><span class="emphasis"><em>UDT</em></span>
 130             <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; ">
 131 <li class="listitem">
 132                   <code class="computeroutput"><span class="identifier">subranged</span><span class="special">=</span><span class="keyword">false</span></code>
 133                 </li>
 134 <li class="listitem">
 135                   <code class="computeroutput"><span class="identifier">supertype</span><span class="special">=</span><span class="identifier">Target</span></code>
 136                 </li>
 137 <li class="listitem">
 138                   <code class="computeroutput"><span class="identifier">subtype</span><span class="special">=</span><span class="identifier">Source</span></code>
 139                 </li>
 140 </ul></div>
 141           </li>
 142 </ul></div>
 143 <p>
 144         The <code class="computeroutput"><span class="identifier">Traits</span></code> member <code class="computeroutput"><span class="identifier">udt_mixture</span></code> can be used to detect whether
 145         a UDT is involved and to infer the validity of the other members as shown
 146         above.
 147       </p>
 148 <h5>
 149 <a name="boost_numericconversion.type_requirements_and_user_defined_types_support.udt_s_special_semantics.h1"></a>
 150         <span class="phrase"><a name="boost_numericconversion.type_requirements_and_user_defined_types_support.udt_s_special_semantics.range_checking"></a></span><a class="link" href="type_requirements_and_user_defined_types_support.html#boost_numericconversion.type_requirements_and_user_defined_types_support.udt_s_special_semantics.range_checking">Range
 151         Checking</a>
 152       </h5>
 153 <p>
 154         Because User Defined Numeric Types might have peculiar ranges (such as an
 155         unbounded range), this library does not attempt to supply a meaningful range
 156         checking logic when UDTs are involved in a conversion. Therefore, if either
 157         Target or Source are not built-in types, the bundled range checking of the
 158         <code class="computeroutput"><span class="identifier">converter</span><span class="special">&lt;&gt;</span></code>
 159         function object is automatically disabled. However, it is possible to supply
 160         a user-defined range-checker. See <a class="link" href="type_requirements_and_user_defined_types_support.html#boost_numericconversion.type_requirements_and_user_defined_types_support.special_policies" title="Special Policies">Special
 161         Policies</a>
 162       </p>
 163 </div>
 164 <div class="section">
 165 <div class="titlepage"><div><div><h3 class="title">
 166 <a name="boost_numericconversion.type_requirements_and_user_defined_types_support.special_policies"></a><a class="link" href="type_requirements_and_user_defined_types_support.html#boost_numericconversion.type_requirements_and_user_defined_types_support.special_policies" title="Special Policies">Special
 167       Policies</a>
 168 </h3></div></div></div>
 169 <p>
 170         There are two components of the <code class="computeroutput"><span class="identifier">converter</span><span class="special">&lt;&gt;</span></code> class that might require special
 171         behavior if User Defined Numeric Types are involved: the Range Checking and
 172         the Raw Conversion.
 173       </p>
 174 <p>
 175         When both Target and Source are built-in types, the converter class uses
 176         an internal range checking logic which is optimized and customized for the
 177         combined properties of the types.
 178       </p>
 179 <p>
 180         However, this internal logic is disabled when either type is User Defined.
 181         In this case, the user can specify an <span class="emphasis"><em>external</em></span> range
 182         checking policy which will be used in place of the internal code. See <a class="link" href="type_requirements_and_user_defined_types_support.html#boost_numericconversion.type_requirements_and_user_defined_types_support.udts_with_numeric_cast" title="UDTs with numeric_cast">numeric_cast_traits</a>
 183         for details on using UDTs with <code class="computeroutput"><span class="identifier">numeric_cast</span></code>.
 184       </p>
 185 <p>
 186         The converter class performs the actual conversion using a Raw Converter
 187         policy. The default raw converter simply performs a <code class="computeroutput"><span class="keyword">static_cast</span><span class="special">&lt;</span><span class="identifier">Target</span><span class="special">&gt;(</span><span class="identifier">source</span><span class="special">)</span></code>.
 188       </p>
 189 <p>
 190         However, if the a UDT is involved, the <code class="computeroutput"><span class="keyword">static_cast</span></code>
 191         might not work. In this case, the user can implement and pass a different
 192         raw converter policy. See <a class="link" href="numeric_converter_policy_classes.html#boost_numericconversion.numeric_converter_policy_classes.policy_rawconverter" title="Policy RawConverter">RawConverter</a>
 193         policy for details.
 194       </p>
 195 </div>
 196 <div class="section">
 197 <div class="titlepage"><div><div><h3 class="title">
 198 <a name="boost_numericconversion.type_requirements_and_user_defined_types_support.udts_with_numeric_cast"></a><a class="link" href="type_requirements_and_user_defined_types_support.html#boost_numericconversion.type_requirements_and_user_defined_types_support.udts_with_numeric_cast" title="UDTs with numeric_cast">UDTs
 199       with numeric_cast</a>
 200 </h3></div></div></div>
 201 <p>
 202         In order to employ UDTs with <code class="computeroutput"><span class="identifier">numeric_cast</span></code>,
 203         the user should define a <code class="computeroutput"><span class="identifier">numeric_cast_traits</span></code>
 204         specialization on the UDT for each conversion. Here is an example of specializations
 205         for converting between the UDT and any other type:
 206       </p>
 207 <pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span> <span class="keyword">namespace</span> <span class="identifier">numeric</span> <span class="special">{</span>
 208 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Source</span><span class="special">&gt;</span>
 209 <span class="keyword">struct</span> <span class="identifier">numeric_cast_traits</span><span class="special">&lt;</span><span class="identifier">UDT</span><span class="special">,</span> <span class="identifier">Source</span><span class="special">&gt;</span>
 210 <span class="special">{</span>
 211     <span class="keyword">typedef</span> <span class="identifier">conversion_traits</span><span class="special">&lt;</span><span class="identifier">UDT</span><span class="special">,</span> <span class="identifier">Source</span><span class="special">&gt;</span>      <span class="identifier">conv_traits</span><span class="special">;</span>
 212
 213     <span class="comment">//! The following are required:</span>
 214     <span class="keyword">typedef</span> <span class="identifier">YourOverflowHandlerPolicy</span>           <span class="identifier">overflow_policy</span><span class="special">;</span>
 215     <span class="keyword">typedef</span> <span class="identifier">YourRangeCheckerPolicy</span><span class="special">&lt;</span><span class="identifier">conv_traits</span><span class="special">&gt;</span> <span class="identifier">range_checking_policy</span><span class="special">;</span>
 216     <span class="keyword">typedef</span> <span class="identifier">YourFloat2IntRounderPolicy</span><span class="special">&lt;</span><span class="identifier">Source</span><span class="special">&gt;</span>  <span class="identifier">rounding_policy</span><span class="special">;</span>
 217 <span class="special">};</span>
 218 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Target</span><span class="special">&gt;</span>
 219 <span class="keyword">struct</span> <span class="identifier">numeric_cast_traits</span><span class="special">&lt;</span><span class="identifier">Target</span><span class="special">,</span> <span class="identifier">UDT</span><span class="special">&gt;</span>
 220 <span class="special">{</span>
 221     <span class="keyword">typedef</span> <span class="identifier">conversion_traits</span><span class="special">&lt;</span><span class="identifier">Target</span><span class="special">,</span> <span class="identifier">UDT</span><span class="special">&gt;</span>      <span class="identifier">conv_traits</span><span class="special">;</span>
 222
 223     <span class="comment">//! The following are required:</span>
 224     <span class="keyword">typedef</span> <span class="identifier">YourOverflowHandlerPolicy</span>           <span class="identifier">overflow_policy</span><span class="special">;</span>
 225     <span class="keyword">typedef</span> <span class="identifier">YourRangeCheckerPolicy</span><span class="special">&lt;</span><span class="identifier">conv_traits</span><span class="special">&gt;</span> <span class="identifier">range_checking_policy</span><span class="special">;</span>
 226     <span class="keyword">typedef</span> <span class="identifier">YourFloat2IntRounderPolicy</span><span class="special">&lt;</span><span class="identifier">UDT</span><span class="special">&gt;</span>     <span class="identifier">rounding_policy</span><span class="special">;</span>
 227 <span class="special">};</span>
 228 <span class="special">}}//</span><span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">;</span>
 229 </pre>
 230 <p>
 231         These specializations are already defined with default values for the built-in
 232         numeric types. It is possible to disable the generation of specializations
 233         for built-in types by defining <code class="computeroutput"><span class="identifier">BOOST_NUMERIC_CONVERSION_RELAX_BUILT_IN_CAST_TRAITS</span></code>.
 234         For details on defining custom policies see <a class="link" href="numeric_converter_policy_classes.html" title="Numeric Converter Policy Classes">Converter
 235         Policies</a>.
 236       </p>
 237 <p>
 238         Here is a full example of how to define a custom UDT for use with <code class="computeroutput"><span class="identifier">numeric_cast</span></code>:
 239       </p>
 240 <pre class="programlisting"><span class="comment">//! Define a simple custom number</span>
 241 <span class="keyword">struct</span> <span class="identifier">Double</span>
 242     <span class="special">:</span>   <span class="identifier">boost</span><span class="special">::</span><span class="identifier">ordered_field_operators</span>
 243         <span class="special">&lt;</span>
 244             <span class="identifier">Double</span>
 245           <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">ordered_field_operators2</span><span class="special">&lt;</span> <span class="identifier">Double</span><span class="special">,</span> <span class="keyword">long</span> <span class="keyword">double</span>
 246           <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">ordered_field_operators2</span><span class="special">&lt;</span> <span class="identifier">Double</span><span class="special">,</span> <span class="keyword">double</span>
 247           <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">ordered_field_operators2</span><span class="special">&lt;</span> <span class="identifier">Double</span><span class="special">,</span> <span class="keyword">float</span>
 248           <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">ordered_field_operators2</span><span class="special">&lt;</span> <span class="identifier">Double</span><span class="special">,</span> <span class="keyword">int</span>
 249           <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">ordered_field_operators2</span><span class="special">&lt;</span> <span class="identifier">Double</span><span class="special">,</span> <span class="keyword">unsigned</span> <span class="keyword">int</span>
 250           <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">ordered_field_operators2</span><span class="special">&lt;</span> <span class="identifier">Double</span><span class="special">,</span> <span class="keyword">long</span>
 251           <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">ordered_field_operators2</span><span class="special">&lt;</span> <span class="identifier">Double</span><span class="special">,</span> <span class="keyword">unsigned</span> <span class="keyword">long</span>
 252           <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">ordered_field_operators2</span><span class="special">&lt;</span> <span class="identifier">Double</span><span class="special">,</span> <span class="keyword">long</span> <span class="keyword">long</span>
 253           <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">ordered_field_operators2</span><span class="special">&lt;</span> <span class="identifier">Double</span><span class="special">,</span> <span class="keyword">unsigned</span> <span class="keyword">long</span> <span class="keyword">long</span>
 254           <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">ordered_field_operators2</span><span class="special">&lt;</span> <span class="identifier">Double</span><span class="special">,</span> <span class="keyword">char</span>
 255           <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">ordered_field_operators2</span><span class="special">&lt;</span> <span class="identifier">Double</span><span class="special">,</span> <span class="keyword">unsigned</span> <span class="keyword">char</span>
 256           <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">ordered_field_operators2</span><span class="special">&lt;</span> <span class="identifier">Double</span><span class="special">,</span> <span class="keyword">short</span>
 257           <span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">ordered_field_operators2</span><span class="special">&lt;</span> <span class="identifier">Double</span><span class="special">,</span> <span class="keyword">unsigned</span> <span class="keyword">short</span>
 258         <span class="special">&gt;</span> <span class="special">&gt;</span> <span class="special">&gt;</span> <span class="special">&gt;</span> <span class="special">&gt;</span> <span class="special">&gt;</span> <span class="special">&gt;</span> <span class="special">&gt;</span> <span class="special">&gt;</span> <span class="special">&gt;</span> <span class="special">&gt;</span> <span class="special">&gt;</span> <span class="special">&gt;</span> <span class="special">&gt;</span>
 259 <span class="special">{</span>
 260     <span class="identifier">Double</span><span class="special">()</span>
 261         <span class="special">:</span> <span class="identifier">v</span><span class="special">(</span><span class="number">0</span><span class="special">)</span>
 262     <span class="special">{}</span>
 263
 264     <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
 265     <span class="keyword">explicit</span> <span class="identifier">Double</span><span class="special">(</span> <span class="identifier">T</span> <span class="identifier">v</span> <span class="special">)</span>
 266         <span class="special">:</span> <span class="identifier">v</span><span class="special">(</span><span class="keyword">static_cast</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">&gt;(</span><span class="identifier">v</span><span class="special">))</span>
 267     <span class="special">{}</span>
 268
 269     <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
 270     <span class="identifier">Double</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=</span> <span class="special">(</span> <span class="identifier">T</span> <span class="identifier">t</span> <span class="special">)</span>
 271     <span class="special">{</span>
 272         <span class="identifier">v</span> <span class="special">=</span> <span class="keyword">static_cast</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">&gt;(</span><span class="identifier">t</span><span class="special">);</span>
 273         <span class="keyword">return</span> <span class="special">*</span><span class="keyword">this</span><span class="special">;</span>
 274     <span class="special">}</span>
 275
 276     <span class="keyword">bool</span> <span class="keyword">operator</span> <span class="special">&lt;</span> <span class="special">(</span> <span class="keyword">const</span> <span class="identifier">Double</span><span class="special">&amp;</span> <span class="identifier">rhs</span> <span class="special">)</span> <span class="keyword">const</span>
 277     <span class="special">{</span>
 278         <span class="keyword">return</span> <span class="identifier">v</span> <span class="special">&lt;</span> <span class="identifier">rhs</span><span class="special">.</span><span class="identifier">v</span><span class="special">;</span>
 279     <span class="special">}</span>
 280
 281     <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
 282     <span class="keyword">bool</span> <span class="keyword">operator</span> <span class="special">&lt;</span> <span class="special">(</span> <span class="identifier">T</span> <span class="identifier">rhs</span> <span class="special">)</span> <span class="keyword">const</span>
 283     <span class="special">{</span>
 284         <span class="keyword">return</span> <span class="identifier">v</span> <span class="special">&lt;</span> <span class="keyword">static_cast</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">&gt;(</span><span class="identifier">rhs</span><span class="special">);</span>
 285     <span class="special">}</span>
 286
 287     <span class="keyword">bool</span> <span class="keyword">operator</span> <span class="special">&gt;</span> <span class="special">(</span> <span class="keyword">const</span> <span class="identifier">Double</span><span class="special">&amp;</span> <span class="identifier">rhs</span> <span class="special">)</span> <span class="keyword">const</span>
 288     <span class="special">{</span>
 289         <span class="keyword">return</span> <span class="identifier">v</span> <span class="special">&gt;</span> <span class="identifier">rhs</span><span class="special">.</span><span class="identifier">v</span><span class="special">;</span>
 290     <span class="special">}</span>
 291
 292     <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
 293     <span class="keyword">bool</span> <span class="keyword">operator</span> <span class="special">&gt;</span> <span class="special">(</span> <span class="identifier">T</span> <span class="identifier">rhs</span> <span class="special">)</span> <span class="keyword">const</span>
 294     <span class="special">{</span>
 295         <span class="keyword">return</span> <span class="identifier">v</span> <span class="special">&gt;</span> <span class="keyword">static_cast</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">&gt;(</span><span class="identifier">rhs</span><span class="special">);</span>
 296     <span class="special">}</span>
 297
 298     <span class="keyword">bool</span> <span class="keyword">operator</span> <span class="special">==(</span> <span class="keyword">const</span> <span class="identifier">Double</span><span class="special">&amp;</span> <span class="identifier">rhs</span> <span class="special">)</span> <span class="keyword">const</span>
 299     <span class="special">{</span>
 300         <span class="keyword">return</span> <span class="identifier">v</span> <span class="special">==</span> <span class="identifier">rhs</span><span class="special">.</span><span class="identifier">v</span><span class="special">;</span>
 301     <span class="special">}</span>
 302
 303     <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
 304     <span class="keyword">bool</span> <span class="keyword">operator</span> <span class="special">==</span> <span class="special">(</span> <span class="identifier">T</span> <span class="identifier">rhs</span> <span class="special">)</span> <span class="keyword">const</span>
 305     <span class="special">{</span>
 306         <span class="keyword">return</span> <span class="identifier">v</span> <span class="special">==</span> <span class="keyword">static_cast</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">&gt;(</span><span class="identifier">rhs</span><span class="special">);</span>
 307     <span class="special">}</span>
 308
 309     <span class="keyword">bool</span> <span class="keyword">operator</span> <span class="special">!()</span> <span class="keyword">const</span>
 310     <span class="special">{</span>
 311         <span class="keyword">return</span> <span class="identifier">v</span> <span class="special">==</span> <span class="number">0</span><span class="special">;</span>
 312     <span class="special">}</span>
 313
 314     <span class="identifier">Double</span> <span class="keyword">operator</span> <span class="special">-()</span> <span class="keyword">const</span>
 315     <span class="special">{</span>
 316         <span class="keyword">return</span> <span class="identifier">Double</span><span class="special">(-</span><span class="identifier">v</span><span class="special">);</span>
 317     <span class="special">}</span>
 318
 319     <span class="identifier">Double</span><span class="special">&amp;</span> <span class="keyword">operator</span> <span class="special">+=(</span> <span class="keyword">const</span> <span class="identifier">Double</span><span class="special">&amp;</span> <span class="identifier">t</span> <span class="special">)</span>
 320     <span class="special">{</span>
 321         <span class="identifier">v</span> <span class="special">+=</span> <span class="identifier">t</span><span class="special">.</span><span class="identifier">v</span><span class="special">;</span>
 322         <span class="keyword">return</span> <span class="special">*</span><span class="keyword">this</span><span class="special">;</span>
 323     <span class="special">}</span>
 324
 325     <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
 326     <span class="identifier">Double</span><span class="special">&amp;</span> <span class="keyword">operator</span> <span class="special">+=(</span> <span class="identifier">T</span> <span class="identifier">t</span> <span class="special">)</span>
 327     <span class="special">{</span>
 328         <span class="identifier">v</span> <span class="special">+=</span> <span class="keyword">static_cast</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">&gt;(</span><span class="identifier">t</span><span class="special">);</span>
 329         <span class="keyword">return</span> <span class="special">*</span><span class="keyword">this</span><span class="special">;</span>
 330     <span class="special">}</span>
 331
 332     <span class="identifier">Double</span><span class="special">&amp;</span> <span class="keyword">operator</span> <span class="special">-=(</span> <span class="keyword">const</span> <span class="identifier">Double</span><span class="special">&amp;</span> <span class="identifier">t</span> <span class="special">)</span>
 333     <span class="special">{</span>
 334         <span class="identifier">v</span> <span class="special">-=</span> <span class="identifier">t</span><span class="special">.</span><span class="identifier">v</span><span class="special">;</span>
 335         <span class="keyword">return</span> <span class="special">*</span><span class="keyword">this</span><span class="special">;</span>
 336     <span class="special">}</span>
 337
 338     <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
 339     <span class="identifier">Double</span><span class="special">&amp;</span> <span class="keyword">operator</span> <span class="special">-=(</span> <span class="identifier">T</span> <span class="identifier">t</span> <span class="special">)</span>
 340     <span class="special">{</span>
 341         <span class="identifier">v</span> <span class="special">-=</span> <span class="keyword">static_cast</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">&gt;(</span><span class="identifier">t</span><span class="special">);</span>
 342         <span class="keyword">return</span> <span class="special">*</span><span class="keyword">this</span><span class="special">;</span>
 343     <span class="special">}</span>
 344
 345     <span class="identifier">Double</span><span class="special">&amp;</span> <span class="keyword">operator</span> <span class="special">*=</span> <span class="special">(</span> <span class="keyword">const</span> <span class="identifier">Double</span><span class="special">&amp;</span> <span class="identifier">factor</span> <span class="special">)</span>
 346     <span class="special">{</span>
 347         <span class="identifier">v</span> <span class="special">*=</span> <span class="identifier">factor</span><span class="special">.</span><span class="identifier">v</span><span class="special">;</span>
 348         <span class="keyword">return</span> <span class="special">*</span><span class="keyword">this</span><span class="special">;</span>
 349     <span class="special">}</span>
 350
 351     <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
 352     <span class="identifier">Double</span><span class="special">&amp;</span> <span class="keyword">operator</span> <span class="special">*=(</span> <span class="identifier">T</span> <span class="identifier">t</span> <span class="special">)</span>
 353     <span class="special">{</span>
 354         <span class="identifier">v</span> <span class="special">*=</span> <span class="keyword">static_cast</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">&gt;(</span><span class="identifier">t</span><span class="special">);</span>
 355         <span class="keyword">return</span> <span class="special">*</span><span class="keyword">this</span><span class="special">;</span>
 356     <span class="special">}</span>
 357
 358     <span class="identifier">Double</span><span class="special">&amp;</span> <span class="keyword">operator</span> <span class="special">/=</span> <span class="special">(</span><span class="keyword">const</span> <span class="identifier">Double</span><span class="special">&amp;</span> <span class="identifier">divisor</span><span class="special">)</span>
 359     <span class="special">{</span>
 360         <span class="identifier">v</span> <span class="special">/=</span> <span class="identifier">divisor</span><span class="special">.</span><span class="identifier">v</span><span class="special">;</span>
 361         <span class="keyword">return</span> <span class="special">*</span><span class="keyword">this</span><span class="special">;</span>
 362     <span class="special">}</span>
 363
 364     <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
 365     <span class="identifier">Double</span><span class="special">&amp;</span> <span class="keyword">operator</span> <span class="special">/=(</span> <span class="identifier">T</span> <span class="identifier">t</span> <span class="special">)</span>
 366     <span class="special">{</span>
 367          <span class="identifier">v</span> <span class="special">/=</span> <span class="keyword">static_cast</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">&gt;(</span><span class="identifier">t</span><span class="special">);</span>
 368         <span class="keyword">return</span> <span class="special">(*</span><span class="keyword">this</span><span class="special">);</span>
 369     <span class="special">}</span>
 370
 371     <span class="keyword">double</span> <span class="identifier">v</span><span class="special">;</span>
 372 <span class="special">};</span>
 373
 374 <span class="comment">//! Define numeric_limits for the custom type.</span>
 375 <span class="keyword">namespace</span> <span class="identifier">std</span>
 376 <span class="special">{</span>
 377     <span class="keyword">template</span><span class="special">&lt;&gt;</span>
 378     <span class="keyword">class</span> <span class="identifier">numeric_limits</span><span class="special">&lt;</span><span class="identifier">Double</span><span class="special">&gt;</span> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">numeric_limits</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">&gt;</span>
 379     <span class="special">{</span>
 380     <span class="keyword">public</span><span class="special">:</span>
 381
 382         <span class="comment">//! Limit our Double to a range of +/- 100.0</span>
 383         <span class="keyword">static</span> <span class="identifier">Double</span> <span class="special">(</span><span class="identifier">min</span><span class="special">)()</span>
 384         <span class="special">{</span>
 385             <span class="keyword">return</span> <span class="identifier">Double</span><span class="special">(</span><span class="number">1.e-2</span><span class="special">);</span>
 386         <span class="special">}</span>
 387
 388         <span class="keyword">static</span> <span class="identifier">Double</span> <span class="special">(</span><span class="identifier">max</span><span class="special">)()</span>
 389         <span class="special">{</span>
 390             <span class="keyword">return</span> <span class="identifier">Double</span><span class="special">(</span><span class="number">1.e2</span><span class="special">);</span>
 391         <span class="special">}</span>
 392
 393         <span class="keyword">static</span> <span class="identifier">Double</span> <span class="identifier">epsilon</span><span class="special">()</span>
 394         <span class="special">{</span>
 395             <span class="keyword">return</span> <span class="identifier">Double</span><span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">numeric_limits</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">&gt;::</span><span class="identifier">epsilon</span><span class="special">()</span> <span class="special">);</span>
 396         <span class="special">}</span>
 397     <span class="special">};</span>
 398 <span class="special">}</span>
 399
 400 <span class="comment">//! Define range checking and overflow policies.</span>
 401 <span class="keyword">namespace</span> <span class="identifier">custom</span>
 402 <span class="special">{</span>
 403     <span class="comment">//! Define a custom range checker</span>
 404     <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Traits</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">OverFlowHandler</span><span class="special">&gt;</span>
 405     <span class="keyword">struct</span> <span class="identifier">range_checker</span>
 406     <span class="special">{</span>
 407         <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">Traits</span><span class="special">::</span><span class="identifier">argument_type</span> <span class="identifier">argument_type</span> <span class="special">;</span>
 408         <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">Traits</span><span class="special">::</span><span class="identifier">source_type</span> <span class="identifier">S</span><span class="special">;</span>
 409         <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">Traits</span><span class="special">::</span><span class="identifier">target_type</span> <span class="identifier">T</span><span class="special">;</span>
 410
 411         <span class="comment">//! Check range of integral types.</span>
 412         <span class="keyword">static</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">::</span><span class="identifier">range_check_result</span> <span class="identifier">out_of_range</span><span class="special">(</span> <span class="identifier">argument_type</span> <span class="identifier">s</span> <span class="special">)</span>
 413         <span class="special">{</span>
 414             <span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">;</span>
 415             <span class="keyword">if</span><span class="special">(</span> <span class="identifier">s</span> <span class="special">&gt;</span> <span class="identifier">bounds</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">highest</span><span class="special">()</span> <span class="special">)</span>
 416                 <span class="keyword">return</span> <span class="identifier">cPosOverflow</span><span class="special">;</span>
 417             <span class="keyword">else</span> <span class="keyword">if</span><span class="special">(</span> <span class="identifier">s</span> <span class="special">&lt;</span> <span class="identifier">bounds</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">lowest</span><span class="special">()</span> <span class="special">)</span>
 418                 <span class="keyword">return</span> <span class="identifier">cNegOverflow</span><span class="special">;</span>
 419             <span class="keyword">else</span>
 420                 <span class="keyword">return</span> <span class="identifier">cInRange</span><span class="special">;</span>
 421         <span class="special">}</span>
 422
 423         <span class="keyword">static</span> <span class="keyword">void</span> <span class="identifier">validate_range</span> <span class="special">(</span> <span class="identifier">argument_type</span> <span class="identifier">s</span> <span class="special">)</span>
 424         <span class="special">{</span>
 425             <span class="identifier">BOOST_STATIC_ASSERT</span><span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">numeric_limits</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">is_bounded</span> <span class="special">);</span>
 426             <span class="identifier">OverFlowHandler</span><span class="special">()(</span> <span class="identifier">out_of_range</span><span class="special">(</span><span class="identifier">s</span><span class="special">)</span> <span class="special">);</span>
 427         <span class="special">}</span>
 428     <span class="special">};</span>
 429
 430     <span class="comment">//! Overflow handler</span>
 431     <span class="keyword">struct</span> <span class="identifier">positive_overflow</span><span class="special">{};</span>
 432     <span class="keyword">struct</span> <span class="identifier">negative_overflow</span><span class="special">{};</span>
 433
 434     <span class="keyword">struct</span> <span class="identifier">overflow_handler</span>
 435     <span class="special">{</span>
 436         <span class="keyword">void</span> <span class="keyword">operator</span><span class="special">()</span> <span class="special">(</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">::</span><span class="identifier">range_check_result</span> <span class="identifier">r</span> <span class="special">)</span>
 437         <span class="special">{</span>
 438             <span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">;</span>
 439             <span class="keyword">if</span><span class="special">(</span> <span class="identifier">r</span> <span class="special">==</span> <span class="identifier">cNegOverflow</span> <span class="special">)</span>
 440                 <span class="keyword">throw</span> <span class="identifier">negative_overflow</span><span class="special">()</span> <span class="special">;</span>
 441             <span class="keyword">else</span> <span class="keyword">if</span><span class="special">(</span> <span class="identifier">r</span> <span class="special">==</span> <span class="identifier">cPosOverflow</span> <span class="special">)</span>
 442                 <span class="keyword">throw</span> <span class="identifier">positive_overflow</span><span class="special">()</span> <span class="special">;</span>
 443         <span class="special">}</span>
 444     <span class="special">};</span>
 445
 446     <span class="comment">//! Define a rounding policy and specialize on the custom type.</span>
 447     <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">S</span><span class="special">&gt;</span>
 448     <span class="keyword">struct</span> <span class="identifier">Ceil</span> <span class="special">:</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">::</span><span class="identifier">Ceil</span><span class="special">&lt;</span><span class="identifier">S</span><span class="special">&gt;{};</span>
 449
 450     <span class="keyword">template</span><span class="special">&lt;&gt;</span>
 451     <span class="keyword">struct</span> <span class="identifier">Ceil</span><span class="special">&lt;</span><span class="identifier">Double</span><span class="special">&gt;</span>
 452     <span class="special">{</span>
 453       <span class="keyword">typedef</span> <span class="identifier">Double</span> <span class="identifier">source_type</span><span class="special">;</span>
 454
 455       <span class="keyword">typedef</span> <span class="identifier">Double</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">argument_type</span><span class="special">;</span>
 456
 457       <span class="keyword">static</span> <span class="identifier">source_type</span> <span class="identifier">nearbyint</span> <span class="special">(</span> <span class="identifier">argument_type</span> <span class="identifier">s</span> <span class="special">)</span>
 458       <span class="special">{</span>
 459 <span class="preprocessor">#if</span> <span class="special">!</span><span class="identifier">defined</span><span class="special">(</span><span class="identifier">BOOST_NO_STDC_NAMESPACE</span><span class="special">)</span>
 460           <span class="keyword">using</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">ceil</span> <span class="special">;</span>
 461 <span class="preprocessor">#endif</span>
 462           <span class="keyword">return</span> <span class="identifier">Double</span><span class="special">(</span> <span class="identifier">ceil</span><span class="special">(</span><span class="identifier">s</span><span class="special">.</span><span class="identifier">v</span><span class="special">)</span> <span class="special">);</span>
 463       <span class="special">}</span>
 464
 465       <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">integral_c</span><span class="special">&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">float_round_style</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">round_toward_infinity</span><span class="special">&gt;</span> <span class="identifier">round_style</span><span class="special">;</span>
 466     <span class="special">};</span>
 467
 468     <span class="comment">//! Define a rounding policy and specialize on the custom type.</span>
 469     <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">S</span><span class="special">&gt;</span>
 470     <span class="keyword">struct</span> <span class="identifier">Trunc</span><span class="special">:</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">::</span><span class="identifier">Trunc</span><span class="special">&lt;</span><span class="identifier">S</span><span class="special">&gt;{};</span>
 471
 472     <span class="keyword">template</span><span class="special">&lt;&gt;</span>
 473     <span class="keyword">struct</span> <span class="identifier">Trunc</span><span class="special">&lt;</span><span class="identifier">Double</span><span class="special">&gt;</span>
 474     <span class="special">{</span>
 475       <span class="keyword">typedef</span> <span class="identifier">Double</span> <span class="identifier">source_type</span><span class="special">;</span>
 476
 477       <span class="keyword">typedef</span> <span class="identifier">Double</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">argument_type</span><span class="special">;</span>
 478
 479       <span class="keyword">static</span> <span class="identifier">source_type</span> <span class="identifier">nearbyint</span> <span class="special">(</span> <span class="identifier">argument_type</span> <span class="identifier">s</span> <span class="special">)</span>
 480       <span class="special">{</span>
 481 <span class="preprocessor">#if</span> <span class="special">!</span><span class="identifier">defined</span><span class="special">(</span><span class="identifier">BOOST_NO_STDC_NAMESPACE</span><span class="special">)</span>
 482           <span class="keyword">using</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">floor</span><span class="special">;</span>
 483 <span class="preprocessor">#endif</span>
 484           <span class="keyword">return</span> <span class="identifier">Double</span><span class="special">(</span> <span class="identifier">floor</span><span class="special">(</span><span class="identifier">s</span><span class="special">.</span><span class="identifier">v</span><span class="special">)</span> <span class="special">);</span>
 485       <span class="special">}</span>
 486
 487       <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">integral_c</span><span class="special">&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">float_round_style</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">round_toward_zero</span><span class="special">&gt;</span> <span class="identifier">round_style</span><span class="special">;</span>
 488     <span class="special">};</span>
 489 <span class="special">}//</span><span class="keyword">namespace</span> <span class="identifier">custom</span><span class="special">;</span>
 490
 491 <span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span> <span class="keyword">namespace</span> <span class="identifier">numeric</span> <span class="special">{</span>
 492
 493     <span class="comment">//! Define the numeric_cast_traits specializations on the custom type.</span>
 494     <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">S</span><span class="special">&gt;</span>
 495     <span class="keyword">struct</span> <span class="identifier">numeric_cast_traits</span><span class="special">&lt;</span><span class="identifier">Double</span><span class="special">,</span> <span class="identifier">S</span><span class="special">&gt;</span>
 496     <span class="special">{</span>
 497         <span class="keyword">typedef</span> <span class="identifier">custom</span><span class="special">::</span><span class="identifier">overflow_handler</span>                         <span class="identifier">overflow_policy</span><span class="special">;</span>
 498         <span class="keyword">typedef</span> <span class="identifier">custom</span><span class="special">::</span><span class="identifier">range_checker</span>
 499                 <span class="special">&lt;</span>
 500                     <span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">::</span><span class="identifier">conversion_traits</span><span class="special">&lt;</span><span class="identifier">Double</span><span class="special">,</span> <span class="identifier">S</span><span class="special">&gt;</span>
 501                   <span class="special">,</span> <span class="identifier">overflow_policy</span>
 502                 <span class="special">&gt;</span>                                                <span class="identifier">range_checking_policy</span><span class="special">;</span>
 503         <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">::</span><span class="identifier">Trunc</span><span class="special">&lt;</span><span class="identifier">S</span><span class="special">&gt;</span>                         <span class="identifier">rounding_policy</span><span class="special">;</span>
 504     <span class="special">};</span>
 505
 506     <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
 507     <span class="keyword">struct</span> <span class="identifier">numeric_cast_traits</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">Double</span><span class="special">&gt;</span>
 508     <span class="special">{</span>
 509         <span class="keyword">typedef</span> <span class="identifier">custom</span><span class="special">::</span><span class="identifier">overflow_handler</span>                         <span class="identifier">overflow_policy</span><span class="special">;</span>
 510         <span class="keyword">typedef</span> <span class="identifier">custom</span><span class="special">::</span><span class="identifier">range_checker</span>
 511                 <span class="special">&lt;</span>
 512                     <span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">::</span><span class="identifier">conversion_traits</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">Double</span><span class="special">&gt;</span>
 513                   <span class="special">,</span> <span class="identifier">overflow_policy</span>
 514                 <span class="special">&gt;</span>                                                <span class="identifier">range_checking_policy</span><span class="special">;</span>
 515         <span class="keyword">typedef</span> <span class="identifier">custom</span><span class="special">::</span><span class="identifier">Trunc</span><span class="special">&lt;</span><span class="identifier">Double</span><span class="special">&gt;</span>                            <span class="identifier">rounding_policy</span><span class="special">;</span>
 516     <span class="special">};</span>
 517
 518     <span class="comment">//! Define the conversion from the custom type to built-in types and vice-versa.</span>
 519     <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
 520     <span class="keyword">struct</span> <span class="identifier">raw_converter</span><span class="special">&lt;</span> <span class="identifier">conversion_traits</span><span class="special">&lt;</span> <span class="identifier">T</span><span class="special">,</span> <span class="identifier">Double</span> <span class="special">&gt;</span> <span class="special">&gt;</span>
 521     <span class="special">{</span>
 522         <span class="keyword">static</span> <span class="identifier">T</span> <span class="identifier">low_level_convert</span> <span class="special">(</span> <span class="keyword">const</span> <span class="identifier">Double</span><span class="special">&amp;</span> <span class="identifier">n</span> <span class="special">)</span>
 523         <span class="special">{</span>
 524             <span class="keyword">return</span> <span class="keyword">static_cast</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;(</span> <span class="identifier">n</span><span class="special">.</span><span class="identifier">v</span> <span class="special">);</span>
 525         <span class="special">}</span>
 526     <span class="special">};</span>
 527
 528     <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">S</span><span class="special">&gt;</span>
 529     <span class="keyword">struct</span> <span class="identifier">raw_converter</span><span class="special">&lt;</span> <span class="identifier">conversion_traits</span><span class="special">&lt;</span> <span class="identifier">Double</span><span class="special">,</span> <span class="identifier">S</span> <span class="special">&gt;</span> <span class="special">&gt;</span>
 530     <span class="special">{</span>
 531         <span class="keyword">static</span> <span class="identifier">Double</span> <span class="identifier">low_level_convert</span> <span class="special">(</span> <span class="keyword">const</span> <span class="identifier">S</span><span class="special">&amp;</span> <span class="identifier">n</span> <span class="special">)</span>
 532         <span class="special">{</span>
 533             <span class="keyword">return</span> <span class="identifier">Double</span><span class="special">(</span><span class="identifier">n</span><span class="special">);</span>
 534         <span class="special">}</span>
 535     <span class="special">};</span>
 536 <span class="special">}}//</span><span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric</span><span class="special">;</span>
 537 </pre>
 538 </div>
 539 </div>
 540 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 541 <td align="left"></td>
 542 <td align="right"><div class="copyright-footer">Copyright &#169; 2004-2007 Fernando
 543       Luis Cacciola Carballal<p>
 544         Distributed under the Boost Software License, Version 1.0. (See accompanying
 545         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>)
 546       </p>
 547 </div></td>
 548 </tr></table>
 549 <hr>
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