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<title>Chapter 35. Boost.TypeIndex 4.0</title>
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<div><h2 class="title">
<a name="boost_typeindex"></a>Chapter 35. Boost.TypeIndex 4.0</h2></div>
<div><p class="copyright">Copyright © 2012-2014 Antony Polukhin</p></div>
<div><div class="legalnotice">
<a name="boost_typeindex.legal"></a><p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
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>)
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<div class="toc">
<p><b>Table of Contents</b></p>
<dl class="toc">
<dt><span class="section"><a href="boost_typeindex.html#boost_typeindex.motivation">Motivation</a></span></dt>
<dt><span class="section"><a href="boost_typeindex/getting_started.html">Getting started</a></span></dt>
<dd><dl>
<dt><span class="section"><a href="boost_typeindex/getting_started.html#boost_typeindex.getting_started.how_to_use">How to use</a></span></dt>
<dt><span class="section"><a href="boost_typeindex/getting_started.html#boost_typeindex.getting_started.example_with_boost_any">Example
with Boost.Any</a></span></dt>
<dt><span class="section"><a href="boost_typeindex/getting_started.html#boost_typeindex.getting_started.example_with_boost_variant">Example
with Boost.Variant</a></span></dt>
</dl></dd>
<dt><span class="section"><a href="boost_typeindex/config.html">Configuring and building the library</a></span></dt>
<dt><span class="section"><a href="boost_typeindex/how_it_works.html">How it works</a></span></dt>
<dt><span class="section"><a href="boost_typeindex/examples.html">Examples</a></span></dt>
<dd><dl>
<dt><span class="section"><a href="boost_typeindex/examples.html#boost_typeindex.examples.getting_human_readable_and_mangl">Getting
human readable and mangled type names</a></span></dt>
<dt><span class="section"><a href="boost_typeindex/examples.html#boost_typeindex.examples.storing_information_about_a_type">Storing
information about a type in container </a></span></dt>
<dt><span class="section"><a href="boost_typeindex/examples.html#boost_typeindex.examples.getting_through_the_inheritance_">Getting
through the inheritance to receive a real type name </a></span></dt>
<dt><span class="section"><a href="boost_typeindex/examples.html#boost_typeindex.examples.exact_type_matching_storing_type">Exact
type matching: storing type with const, volatile and reference qualifiers</a></span></dt>
<dt><span class="section"><a href="boost_typeindex/examples.html#boost_typeindex.examples.table_of_raw_name_and_pretty_nam">Table
of raw_name() and pretty_name() outputs with and without RTTI </a></span></dt>
</dl></dd>
<dt><span class="section"><a href="boost_typeindex_header_reference.html">Boost.TypeIndex Header Reference</a></span></dt>
<dd><dl>
<dt><span class="section"><a href="boost_typeindex_header_reference.html#header.boost.type_index_hpp">Header <boost/type_index.hpp></a></span></dt>
<dt><span class="section"><a href="boost_typeindex_header_reference.html#header.boost.type_index.ctti_type_index_hpp">Header <boost/type_index/ctti_type_index.hpp></a></span></dt>
<dt><span class="section"><a href="boost_typeindex_header_reference.html#header.boost.type_index.stl_type_index_hpp">Header <boost/type_index/stl_type_index.hpp></a></span></dt>
<dt><span class="section"><a href="boost_typeindex_header_reference.html#header.boost.type_index.type_index_facade_hpp">Header <boost/type_index/type_index_facade.hpp></a></span></dt>
</dl></dd>
<dt><span class="section"><a href="boost_typeindex/making_a_custom_type_index.html">Making a custom
type_index</a></span></dt>
<dd><dl>
<dt><span class="section"><a href="boost_typeindex/making_a_custom_type_index.html#boost_typeindex.making_a_custom_type_index.basics">Basics</a></span></dt>
<dt><span class="section"><a href="boost_typeindex/making_a_custom_type_index.html#boost_typeindex.making_a_custom_type_index.getting_type_infos_at_runtime">Getting
type infos at runtime</a></span></dt>
<dt><span class="section"><a href="boost_typeindex/making_a_custom_type_index.html#boost_typeindex.making_a_custom_type_index.using_new_type_infos_all_around_">Using
new type infos all around the code</a></span></dt>
</dl></dd>
<dt><span class="section"><a href="boost_typeindex/space_and_performance.html">Space and Performance</a></span></dt>
<dt><span class="section"><a href="boost_typeindex/code_bloat.html">Code bloat</a></span></dt>
<dt><span class="section"><a href="boost_typeindex/rtti_emulation_limitations.html">RTTI emulation
limitations</a></span></dt>
<dd><dl>
<dt><span class="section"><a href="boost_typeindex/rtti_emulation_limitations.html#boost_typeindex.rtti_emulation_limitations.define_the_boost_type_index_func">Define
the BOOST_TYPE_INDEX_FUNCTION_SIGNATURE macro</a></span></dt>
<dt><span class="section"><a href="boost_typeindex/rtti_emulation_limitations.html#boost_typeindex.rtti_emulation_limitations.fixing_pretty_name_output">Fixing
pretty_name() output</a></span></dt>
</dl></dd>
<dt><span class="section"><a href="boost_typeindex/mixing_sources_with_rtti_on_and_.html">Mixing
sources with RTTI on and RTTI off</a></span></dt>
<dt><span class="section"><a href="boost_typeindex/acknowledgements.html">Acknowledgements</a></span></dt>
</dl>
</div>
<div class="section">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="boost_typeindex.motivation"></a><a class="link" href="boost_typeindex.html#boost_typeindex.motivation" title="Motivation">Motivation</a>
</h2></div></div></div>
<p>
Sometimes getting and storing information about a type at runtime is required.
For such cases a construction like <code class="computeroutput"><span class="special">&</span><span class="keyword">typeid</span><span class="special">(</span><span class="identifier">T</span><span class="special">)</span></code> or C++11 class <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">type_index</span></code>
is usually used, which is where problems start:
</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<code class="computeroutput"><span class="keyword">typeid</span><span class="special">(</span><span class="identifier">T</span><span class="special">)</span></code> and
<code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">type_index</span></code> require Run Time Type Info
(RTTI)
</li>
<li class="listitem">
some implementations of <code class="computeroutput"><span class="keyword">typeid</span><span class="special">(</span><span class="identifier">T</span><span class="special">)</span></code>
erroneously do not strip const, volatile and references from type
</li>
<li class="listitem">
some compilers have bugs and do not correctly compare <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">type_info</span></code>
objects across shared libraries
</li>
<li class="listitem">
only a few implementations of Standard Library currently provide <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">type_index</span></code>
</li>
<li class="listitem">
no easy way to store type info without stripping const, volatile and references
</li>
<li class="listitem">
no nice and portable way to get human readable type names
</li>
<li class="listitem">
no way to easily make your own type info class
</li>
</ul></div>
<p>
Boost.TypeIndex library was designed to work around all those issues.
</p>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../doc/src/images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
<code class="computeroutput"><span class="identifier">T</span></code> means type here. Think
of it as of <code class="computeroutput"><span class="identifier">T</span></code> in <code class="computeroutput"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span></code>
</p></td></tr>
</table></div>
</div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"><p><small>Last revised: December 14, 2015 at 09:19:39 GMT</small></p></td>
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