doc/html/boost_typeindex/making_a_custom_type_index.html

   1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
   2 <html>
   3 <head>
   4 <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
   5 <title>Making a custom type_index</title>
   6 <link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css">
   7 <meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
   8 <link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset">
   9 <link rel="up" href="../boost_typeindex.html" title="Chapter&#160;41.&#160;Boost.TypeIndex 4.1">
  10 <link rel="prev" href="../boost/typeindex/hash_value_idp761138432.html" title="Function template hash_value">
  11 <link rel="next" href="space_and_performance.html" title="Space and Performance">
  12 </head>
  13 <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
  14 <table cellpadding="2" width="100%"><tr>
  15 <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../boost.png"></td>
  16 <td align="center"><a href="../../../index.html">Home</a></td>
  17 <td align="center"><a href="../../../libs/libraries.htm">Libraries</a></td>
  18 <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
  19 <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
  20 <td align="center"><a href="../../../more/index.htm">More</a></td>
  21 </tr></table>
  22 <hr>
  23 <div class="spirit-nav">
  24 <a accesskey="p" href="../boost/typeindex/hash_value_idp761138432.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../boost_typeindex.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="space_and_performance.html"><img src="../../../doc/src/images/next.png" alt="Next"></a>
  25 </div>
  26 <div class="section">
  27 <div class="titlepage"><div><div><h2 class="title" style="clear: both">
  28 <a name="boost_typeindex.making_a_custom_type_index"></a><a class="link" href="making_a_custom_type_index.html" title="Making a custom type_index">Making a custom
  29     type_index</a>
  30 </h2></div></div></div>
  31 <div class="toc"><dl class="toc">
  32 <dt><span class="section"><a href="making_a_custom_type_index.html#boost_typeindex.making_a_custom_type_index.basics">Basics</a></span></dt>
  33 <dt><span class="section"><a href="making_a_custom_type_index.html#boost_typeindex.making_a_custom_type_index.getting_type_infos_at_runtime">Getting
  34       type infos at runtime</a></span></dt>
  35 <dt><span class="section"><a href="making_a_custom_type_index.html#boost_typeindex.making_a_custom_type_index.using_new_type_infos_all_around_">Using
  36       new type infos all around the code</a></span></dt>
  37 </dl></div>
  38 <p>
  39       Sometimes there may be a need to create your own type info system. This may
  40       be useful if you wish to store some more info about types (PODness, size of
  41       a type, pointers to common functions...) or if you have an idea of a more compact
  42       types representations.
  43     </p>
  44 <div class="section">
  45 <div class="titlepage"><div><div><h3 class="title">
  46 <a name="boost_typeindex.making_a_custom_type_index.basics"></a><a class="link" href="making_a_custom_type_index.html#boost_typeindex.making_a_custom_type_index.basics" title="Basics">Basics</a>
  47 </h3></div></div></div>
  48 <p>
  49         The following example shows how a user defined type_info can be created and
  50         used. Example works with and without RTTI.
  51       </p>
  52 <p>
  53         Consider situation when user uses only those types in <code class="computeroutput"><span class="keyword">typeid</span><span class="special">()</span></code>:
  54       </p>
  55 <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">vector</span><span class="special">&gt;</span>
  56 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">string</span><span class="special">&gt;</span>
  57
  58 <span class="keyword">namespace</span> <span class="identifier">my_namespace</span> <span class="special">{</span>
  59
  60 <span class="keyword">class</span> <span class="identifier">my_class</span><span class="special">;</span>
  61 <span class="keyword">struct</span> <span class="identifier">my_struct</span><span class="special">;</span>
  62
  63 <span class="keyword">typedef</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span><span class="identifier">my_class</span><span class="special">&gt;</span> <span class="identifier">my_classes</span><span class="special">;</span>
  64 <span class="keyword">typedef</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">my_string</span><span class="special">;</span>
  65
  66 <span class="special">}</span> <span class="comment">// namespace my_namespace</span>
  67 </pre>
  68 <p>
  69         In that case user may wish to save space in binary and create it's own type
  70         system. For that case <code class="computeroutput"><span class="identifier">detail</span><span class="special">::</span><span class="identifier">typenum</span><span class="special">&lt;&gt;</span></code> meta function is added. Depending
  71         on the input type T this function will return different numeric values.
  72       </p>
  73 <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">type_index</span><span class="special">/</span><span class="identifier">type_index_facade</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
  74
  75 <span class="keyword">namespace</span> <span class="identifier">my_namespace</span> <span class="special">{</span> <span class="keyword">namespace</span> <span class="identifier">detail</span> <span class="special">{</span>
  76     <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> <span class="keyword">struct</span> <span class="identifier">typenum</span><span class="special">;</span>
  77     <span class="keyword">template</span> <span class="special">&lt;&gt;</span> <span class="keyword">struct</span> <span class="identifier">typenum</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">&gt;{</span>       <span class="keyword">enum</span> <span class="special">{</span><span class="identifier">value</span> <span class="special">=</span> <span class="number">0</span><span class="special">};</span> <span class="special">};</span>
  78     <span class="keyword">template</span> <span class="special">&lt;&gt;</span> <span class="keyword">struct</span> <span class="identifier">typenum</span><span class="special">&lt;</span><span class="identifier">my_class</span><span class="special">&gt;{</span>   <span class="keyword">enum</span> <span class="special">{</span><span class="identifier">value</span> <span class="special">=</span> <span class="number">1</span><span class="special">};</span> <span class="special">};</span>
  79     <span class="keyword">template</span> <span class="special">&lt;&gt;</span> <span class="keyword">struct</span> <span class="identifier">typenum</span><span class="special">&lt;</span><span class="identifier">my_struct</span><span class="special">&gt;{</span>  <span class="keyword">enum</span> <span class="special">{</span><span class="identifier">value</span> <span class="special">=</span> <span class="number">2</span><span class="special">};</span> <span class="special">};</span>
  80     <span class="keyword">template</span> <span class="special">&lt;&gt;</span> <span class="keyword">struct</span> <span class="identifier">typenum</span><span class="special">&lt;</span><span class="identifier">my_classes</span><span class="special">&gt;{</span> <span class="keyword">enum</span> <span class="special">{</span><span class="identifier">value</span> <span class="special">=</span> <span class="number">3</span><span class="special">};</span> <span class="special">};</span>
  81     <span class="keyword">template</span> <span class="special">&lt;&gt;</span> <span class="keyword">struct</span> <span class="identifier">typenum</span><span class="special">&lt;</span><span class="identifier">my_string</span><span class="special">&gt;{</span>  <span class="keyword">enum</span> <span class="special">{</span><span class="identifier">value</span> <span class="special">=</span> <span class="number">4</span><span class="special">};</span> <span class="special">};</span>
  82
  83     <span class="comment">// my_typeinfo structure is used to save type number</span>
  84     <span class="keyword">struct</span> <span class="identifier">my_typeinfo</span> <span class="special">{</span>
  85         <span class="keyword">const</span> <span class="keyword">char</span><span class="special">*</span> <span class="keyword">const</span> <span class="identifier">type_</span><span class="special">;</span>
  86     <span class="special">};</span>
  87
  88     <span class="keyword">const</span> <span class="identifier">my_typeinfo</span> <span class="identifier">infos</span><span class="special">[</span><span class="number">5</span><span class="special">]</span> <span class="special">=</span> <span class="special">{</span>
  89         <span class="special">{</span><span class="string">"void"</span><span class="special">},</span> <span class="special">{</span><span class="string">"my_class"</span><span class="special">},</span> <span class="special">{</span><span class="string">"my_struct"</span><span class="special">},</span> <span class="special">{</span><span class="string">"my_classes"</span><span class="special">},</span> <span class="special">{</span><span class="string">"my_string"</span><span class="special">}</span>
  90     <span class="special">};</span>
  91
  92     <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>
  93     <span class="keyword">inline</span> <span class="keyword">const</span> <span class="identifier">my_typeinfo</span><span class="special">&amp;</span> <span class="identifier">my_typeinfo_construct</span><span class="special">()</span> <span class="special">{</span>
  94         <span class="keyword">return</span> <span class="identifier">infos</span><span class="special">[</span><span class="identifier">typenum</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">value</span><span class="special">];</span>
  95     <span class="special">}</span>
  96 <span class="special">}}</span> <span class="comment">// my_namespace::detail</span>
  97 </pre>
  98 <p>
  99         <code class="computeroutput"><span class="identifier">my_type_index</span></code> is a user created
 100         type_index class. If in doubt during this phase, you can always take a look
 101         at the <code class="computeroutput"><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">type_index</span><span class="special">/</span><span class="identifier">ctti_type_index</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
 102         or <code class="computeroutput"><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">type_index</span><span class="special">/</span><span class="identifier">stl_type_index</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
 103         files. Documentation for <code class="computeroutput"><span class="identifier">type_index_facade</span></code>
 104         could be also useful.
 105       </p>
 106 <p>
 107         See implementation of <code class="computeroutput"><span class="identifier">my_type_index</span></code>:
 108       </p>
 109 <pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">my_namespace</span> <span class="special">{</span>
 110
 111 <span class="keyword">class</span> <span class="identifier">my_type_index</span><span class="special">:</span> <span class="keyword">public</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">typeindex</span><span class="special">::</span><span class="identifier">type_index_facade</span><span class="special">&lt;</span><span class="identifier">my_type_index</span><span class="special">,</span> <span class="identifier">detail</span><span class="special">::</span><span class="identifier">my_typeinfo</span><span class="special">&gt;</span> <span class="special">{</span>
 112     <span class="keyword">const</span> <span class="identifier">detail</span><span class="special">::</span><span class="identifier">my_typeinfo</span><span class="special">*</span> <span class="identifier">data_</span><span class="special">;</span>
 113
 114 <span class="keyword">public</span><span class="special">:</span>
 115     <span class="keyword">typedef</span> <span class="identifier">detail</span><span class="special">::</span><span class="identifier">my_typeinfo</span> <span class="identifier">type_info_t</span><span class="special">;</span>
 116
 117     <span class="keyword">inline</span> <span class="identifier">my_type_index</span><span class="special">()</span> <span class="identifier">BOOST_NOEXCEPT</span>
 118         <span class="special">:</span> <span class="identifier">data_</span><span class="special">(&amp;</span><span class="identifier">detail</span><span class="special">::</span><span class="identifier">my_typeinfo_construct</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">&gt;())</span>
 119     <span class="special">{}</span>
 120
 121     <span class="keyword">inline</span> <span class="identifier">my_type_index</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">type_info_t</span><span class="special">&amp;</span> <span class="identifier">data</span><span class="special">)</span> <span class="identifier">BOOST_NOEXCEPT</span>
 122         <span class="special">:</span> <span class="identifier">data_</span><span class="special">(&amp;</span><span class="identifier">data</span><span class="special">)</span>
 123     <span class="special">{}</span>
 124
 125     <span class="keyword">inline</span> <span class="keyword">const</span> <span class="identifier">type_info_t</span><span class="special">&amp;</span>  <span class="identifier">type_info</span><span class="special">()</span> <span class="keyword">const</span> <span class="identifier">BOOST_NOEXCEPT</span> <span class="special">{</span>
 126         <span class="keyword">return</span> <span class="special">*</span><span class="identifier">data_</span><span class="special">;</span>
 127     <span class="special">}</span>
 128
 129     <span class="keyword">inline</span> <span class="keyword">const</span> <span class="keyword">char</span><span class="special">*</span>  <span class="identifier">raw_name</span><span class="special">()</span> <span class="keyword">const</span> <span class="identifier">BOOST_NOEXCEPT</span> <span class="special">{</span>
 130         <span class="keyword">return</span> <span class="identifier">data_</span><span class="special">-&gt;</span><span class="identifier">type_</span><span class="special">;</span>
 131     <span class="special">}</span>
 132
 133     <span class="keyword">inline</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span>  <span class="identifier">pretty_name</span><span class="special">()</span> <span class="keyword">const</span> <span class="special">{</span>
 134         <span class="keyword">return</span> <span class="identifier">data_</span><span class="special">-&gt;</span><span class="identifier">type_</span><span class="special">;</span>
 135     <span class="special">}</span>
 136
 137     <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>
 138     <span class="keyword">inline</span> <span class="keyword">static</span> <span class="identifier">my_type_index</span> <span class="identifier">type_id</span><span class="special">()</span> <span class="identifier">BOOST_NOEXCEPT</span> <span class="special">{</span>
 139         <span class="keyword">return</span> <span class="identifier">detail</span><span class="special">::</span><span class="identifier">my_typeinfo_construct</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;();</span>
 140     <span class="special">}</span>
 141
 142     <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>
 143     <span class="keyword">inline</span> <span class="keyword">static</span> <span class="identifier">my_type_index</span> <span class="identifier">type_id_with_cvr</span><span class="special">()</span> <span class="identifier">BOOST_NOEXCEPT</span> <span class="special">{</span>
 144         <span class="keyword">return</span> <span class="identifier">detail</span><span class="special">::</span><span class="identifier">my_typeinfo_construct</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;();</span>
 145     <span class="special">}</span>
 146
 147     <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>
 148     <span class="keyword">inline</span> <span class="keyword">static</span> <span class="identifier">my_type_index</span> <span class="identifier">type_id_runtime</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">variable</span><span class="special">)</span> <span class="identifier">BOOST_NOEXCEPT</span><span class="special">;</span>
 149 <span class="special">};</span>
 150
 151 <span class="special">}</span> <span class="comment">// namespace my_namespace</span>
 152 </pre>
 153 <p>
 154         Note that we have used the boost::typeindex::type_index_facade class as base.
 155         That class took care about all the helper function and operators (comparison,
 156         hashing, ostreaming and others).
 157       </p>
 158 <p>
 159         Finally we can use the my_type_index class for getting type indexes:
 160       </p>
 161 <pre class="programlisting"><span class="identifier">my_type_index</span>
 162     <span class="identifier">cl1</span> <span class="special">=</span> <span class="identifier">my_type_index</span><span class="special">::</span><span class="identifier">type_id</span><span class="special">&lt;</span><span class="identifier">my_class</span><span class="special">&gt;(),</span>
 163     <span class="identifier">st1</span> <span class="special">=</span> <span class="identifier">my_type_index</span><span class="special">::</span><span class="identifier">type_id</span><span class="special">&lt;</span><span class="identifier">my_struct</span><span class="special">&gt;(),</span>
 164     <span class="identifier">st2</span> <span class="special">=</span> <span class="identifier">my_type_index</span><span class="special">::</span><span class="identifier">type_id</span><span class="special">&lt;</span><span class="identifier">my_struct</span><span class="special">&gt;(),</span>
 165     <span class="identifier">vec</span> <span class="special">=</span> <span class="identifier">my_type_index</span><span class="special">::</span><span class="identifier">type_id</span><span class="special">&lt;</span><span class="identifier">my_classes</span><span class="special">&gt;()</span>
 166 <span class="special">;</span>
 167
 168 <span class="identifier">assert</span><span class="special">(</span><span class="identifier">cl1</span> <span class="special">!=</span> <span class="identifier">st1</span><span class="special">);</span>
 169 <span class="identifier">assert</span><span class="special">(</span><span class="identifier">st2</span> <span class="special">==</span> <span class="identifier">st1</span><span class="special">);</span>
 170 <span class="identifier">assert</span><span class="special">(</span><span class="identifier">vec</span><span class="special">.</span><span class="identifier">pretty_name</span><span class="special">()</span> <span class="special">==</span> <span class="string">"my_classes"</span><span class="special">);</span>
 171 <span class="identifier">assert</span><span class="special">(</span><span class="identifier">cl1</span><span class="special">.</span><span class="identifier">pretty_name</span><span class="special">()</span> <span class="special">==</span> <span class="string">"my_class"</span><span class="special">);</span>
 172 </pre>
 173 </div>
 174 <div class="section">
 175 <div class="titlepage"><div><div><h3 class="title">
 176 <a name="boost_typeindex.making_a_custom_type_index.getting_type_infos_at_runtime"></a><a class="link" href="making_a_custom_type_index.html#boost_typeindex.making_a_custom_type_index.getting_type_infos_at_runtime" title="Getting type infos at runtime">Getting
 177       type infos at runtime</a>
 178 </h3></div></div></div>
 179 <p>
 180         Usually to allow runtime type info we need to register class with some macro.
 181         Let's see how a <code class="computeroutput"><span class="identifier">MY_TYPEINDEX_REGISTER_CLASS</span></code>
 182         macro could be implemented for our <code class="computeroutput"><span class="identifier">my_type_index</span></code>
 183         class:
 184       </p>
 185 <pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">my_namespace</span> <span class="special">{</span> <span class="keyword">namespace</span> <span class="identifier">detail</span> <span class="special">{</span>
 186
 187     <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>
 188     <span class="keyword">inline</span> <span class="keyword">const</span> <span class="identifier">my_typeinfo</span><span class="special">&amp;</span> <span class="identifier">my_typeinfo_construct_ref</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span><span class="special">*)</span> <span class="special">{</span>
 189         <span class="keyword">return</span> <span class="identifier">my_typeinfo_construct</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;();</span>
 190     <span class="special">}</span>
 191
 192 <span class="preprocessor">#define</span> <span class="identifier">MY_TYPEINDEX_REGISTER_CLASS</span>                                             <span class="special">\</span>
 193     <span class="keyword">virtual</span> <span class="keyword">const</span> <span class="identifier">my_namespace</span><span class="special">::</span><span class="identifier">detail</span><span class="special">::</span><span class="identifier">my_typeinfo</span><span class="special">&amp;</span> <span class="identifier">type_id_runtime</span><span class="special">()</span> <span class="keyword">const</span> <span class="special">{</span>  <span class="special">\</span>
 194         <span class="keyword">return</span> <span class="identifier">my_namespace</span><span class="special">::</span><span class="identifier">detail</span><span class="special">::</span><span class="identifier">my_typeinfo_construct_ref</span><span class="special">(</span><span class="keyword">this</span><span class="special">);</span>           <span class="special">\</span>
 195     <span class="special">}</span>
 196
 197 <span class="special">}}</span> <span class="comment">// namespace my_namespace::detail</span>
 198 </pre>
 199 <p>
 200         Now when we have a MY_TYPEINDEX_REGISTER_CLASS, let's implement a <code class="computeroutput"><span class="identifier">my_type_index</span><span class="special">::</span><span class="identifier">type_id_runtime</span></code> method:
 201       </p>
 202 <pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">my_namespace</span> <span class="special">{</span>
 203     <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>
 204     <span class="identifier">my_type_index</span> <span class="identifier">my_type_index</span><span class="special">::</span><span class="identifier">type_id_runtime</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">variable</span><span class="special">)</span> <span class="identifier">BOOST_NOEXCEPT</span> <span class="special">{</span>
 205         <span class="comment">// Classes that were marked with `MY_TYPEINDEX_REGISTER_CLASS` will have a</span>
 206         <span class="comment">// `type_id_runtime()` method.</span>
 207         <span class="keyword">return</span> <span class="identifier">variable</span><span class="special">.</span><span class="identifier">type_id_runtime</span><span class="special">();</span>
 208     <span class="special">}</span>
 209 <span class="special">}</span>
 210 </pre>
 211 <p>
 212         Consider the situation, when <code class="computeroutput"><span class="identifier">my_class</span></code>
 213         and <code class="computeroutput"><span class="identifier">my_struct</span></code> are polymorphic
 214         classes:
 215       </p>
 216 <pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">my_namespace</span> <span class="special">{</span>
 217
 218 <span class="keyword">class</span> <span class="identifier">my_class</span> <span class="special">{</span>
 219 <span class="keyword">public</span><span class="special">:</span>
 220     <span class="identifier">MY_TYPEINDEX_REGISTER_CLASS</span>
 221     <span class="keyword">virtual</span> <span class="special">~</span><span class="identifier">my_class</span><span class="special">()</span> <span class="special">{}</span>
 222 <span class="special">};</span>
 223
 224 <span class="keyword">struct</span> <span class="identifier">my_struct</span><span class="special">:</span> <span class="keyword">public</span> <span class="identifier">my_class</span> <span class="special">{</span>
 225     <span class="identifier">MY_TYPEINDEX_REGISTER_CLASS</span>
 226 <span class="special">};</span>
 227
 228 <span class="special">}</span> <span class="comment">// namespace my_namespace</span>
 229 </pre>
 230 <p>
 231         Now the following example will compile and work.
 232       </p>
 233 <pre class="programlisting"><span class="identifier">my_struct</span> <span class="identifier">str</span><span class="special">;</span>
 234 <span class="identifier">my_class</span><span class="special">&amp;</span> <span class="identifier">reference</span> <span class="special">=</span> <span class="identifier">str</span><span class="special">;</span>
 235 <span class="identifier">assert</span><span class="special">(</span><span class="identifier">my_type_index</span><span class="special">::</span><span class="identifier">type_id</span><span class="special">&lt;</span><span class="identifier">my_struct</span><span class="special">&gt;()</span> <span class="special">==</span> <span class="identifier">my_type_index</span><span class="special">::</span><span class="identifier">type_id_runtime</span><span class="special">(</span><span class="identifier">reference</span><span class="special">));</span>
 236 </pre>
 237 </div>
 238 <div class="section">
 239 <div class="titlepage"><div><div><h3 class="title">
 240 <a name="boost_typeindex.making_a_custom_type_index.using_new_type_infos_all_around_"></a><a class="link" href="making_a_custom_type_index.html#boost_typeindex.making_a_custom_type_index.using_new_type_infos_all_around_" title="Using new type infos all around the code">Using
 241       new type infos all around the code</a>
 242 </h3></div></div></div>
 243 <p>
 244         There is an easy way to force <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">typeindex</span><span class="special">::</span><span class="identifier">type_id</span></code>
 245         to use your own type_index class.
 246       </p>
 247 <p>
 248         All we need to do is just define <code class="computeroutput"><span class="identifier">BOOST_TYPE_INDEX_USER_TYPEINDEX</span></code>
 249         to the full path to header file of your type index class:
 250       </p>
 251 <pre class="programlisting"><span class="comment">// BOOST_TYPE_INDEX_USER_TYPEINDEX must be defined *BEFORE* first inclusion of &lt;boost/type_index.hpp&gt;</span>
 252 <span class="preprocessor">#define</span> <span class="identifier">BOOST_TYPE_INDEX_USER_TYPEINDEX</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/../</span><span class="identifier">libs</span><span class="special">/</span><span class="identifier">type_index</span><span class="special">/</span><span class="identifier">examples</span><span class="special">/</span><span class="identifier">user_defined_typeinfo</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 253 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">type_index</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 254 </pre>
 255 <p>
 256         You'll also need to add some typedefs and macro to your "user_defined_typeinfo.hpp"
 257         header file:
 258       </p>
 259 <pre class="programlisting"><span class="preprocessor">#define</span> <span class="identifier">BOOST_TYPE_INDEX_REGISTER_CLASS</span> <span class="identifier">MY_TYPEINDEX_REGISTER_CLASS</span>
 260 <span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span> <span class="keyword">namespace</span> <span class="identifier">typeindex</span> <span class="special">{</span>
 261     <span class="keyword">typedef</span> <span class="identifier">my_namespace</span><span class="special">::</span><span class="identifier">my_type_index</span> <span class="identifier">type_index</span><span class="special">;</span>
 262 <span class="special">}}</span>
 263 </pre>
 264 <p>
 265         That's it! Now all TypeIndex global methods and typedefs will be using your
 266         class:
 267       </p>
 268 <pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">typeindex</span><span class="special">::</span><span class="identifier">type_index</span> <span class="identifier">worldwide</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">typeindex</span><span class="special">::</span><span class="identifier">type_id</span><span class="special">&lt;</span><span class="identifier">my_classes</span><span class="special">&gt;();</span>
 269 <span class="identifier">assert</span><span class="special">(</span><span class="identifier">worldwide</span><span class="special">.</span><span class="identifier">pretty_name</span><span class="special">()</span> <span class="special">==</span> <span class="string">"my_classes"</span><span class="special">);</span>
 270 <span class="identifier">assert</span><span class="special">(</span><span class="identifier">worldwide</span> <span class="special">==</span> <span class="identifier">my_type_index</span><span class="special">::</span><span class="identifier">type_id</span><span class="special">&lt;</span><span class="identifier">my_classes</span><span class="special">&gt;());</span>
 271 </pre>
 272 </div>
 273 </div>
 274 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 275 <td align="left"></td>
 276 <td align="right"><div class="copyright-footer">Copyright &#169; 2012-2016 Antony Polukhin<p>
 277         Distributed under the Boost Software License, Version 1.0. (See accompanying
 278         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>)
 279       </p>
 280 </div></td>
 281 </tr></table>
 282 <hr>
 283 <div class="spirit-nav">
 284 <a accesskey="p" href="../boost/typeindex/hash_value_idp761138432.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../boost_typeindex.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="space_and_performance.html"><img src="../../../doc/src/images/next.png" alt="Next"></a>
 285 </div>
 286 </body>
 287 </html>