<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>User Defined Specializations</title> <link rel="stylesheet" href="../../../../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.74.0"> <link rel="home" href="../index.html" title="Chapter 1. Boost.TypeTraits"> <link rel="up" href="../index.html" title="Chapter 1. Boost.TypeTraits"> <link rel="prev" href="category/function.html" title="Decomposing Function Types"> <link rel="next" href="intrinsics.html" title="Support for Compiler Intrinsics"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr> <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../boost.png"></td> <td align="center"><a href="../../../../../index.html">Home</a></td> <td align="center"><a href="../../../../../libs/libraries.htm">Libraries</a></td> <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> <td align="center"><a href="../../../../../more/index.htm">More</a></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="category/function.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.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="intrinsics.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> </div> <div class="section" lang="en"> <div class="titlepage"><div><div><h2 class="title" style="clear: both"> <a name="boost_typetraits.user_defined"></a><a class="link" href="user_defined.html" title="User Defined Specializations"> User Defined Specializations</a> </h2></div></div></div> <p> Occationally the end user may need to provide their own specialization for one of the type traits - typically where intrinsic compiler support is required to implement a specific trait fully. These specializations should derive from boost::<a class="link" href="reference/integral_constant.html" title="integral_constant">true_type</a> or boost::<a class="link" href="reference/integral_constant.html" title="integral_constant">false_type</a> as appropriate: </p> <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">type_traits</span><span class="special">/</span><span class="identifier">is_pod</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">type_traits</span><span class="special">/</span><span class="identifier">is_class</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">type_traits</span><span class="special">/</span><span class="identifier">is_union</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> <span class="keyword">struct</span> <span class="identifier">my_pod</span><span class="special">{};</span> <span class="keyword">struct</span> <span class="identifier">my_union</span> <span class="special">{</span> <span class="keyword">char</span> <span class="identifier">c</span><span class="special">;</span> <span class="keyword">int</span> <span class="identifier">i</span><span class="special">;</span> <span class="special">};</span> <span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span> <span class="keyword">template</span><span class="special"><></span> <span class="keyword">struct</span> <a class="link" href="reference/is_pod.html" title="is_pod">is_pod</a><span class="special"><</span><span class="identifier">my_pod</span><span class="special">></span> <span class="special">:</span> <span class="keyword">public</span> <a class="link" href="reference/integral_constant.html" title="integral_constant">true_type</a><span class="special">{};</span> <span class="keyword">template</span><span class="special"><></span> <span class="keyword">struct</span> <a class="link" href="reference/is_pod.html" title="is_pod">is_pod</a><span class="special"><</span><span class="identifier">my_union</span><span class="special">></span> <span class="special">:</span> <span class="keyword">public</span> <a class="link" href="reference/integral_constant.html" title="integral_constant">true_type</a><span class="special">{};</span> <span class="keyword">template</span><span class="special"><></span> <span class="keyword">struct</span> <a class="link" href="reference/is_union.html" title="is_union">is_union</a><span class="special"><</span><span class="identifier">my_union</span><span class="special">></span> <span class="special">:</span> <span class="keyword">public</span> <a class="link" href="reference/integral_constant.html" title="integral_constant">true_type</a><span class="special">{};</span> <span class="keyword">template</span><span class="special"><></span> <span class="keyword">struct</span> <a class="link" href="reference/is_class.html" title="is_class">is_class</a><span class="special"><</span><span class="identifier">my_union</span><span class="special">></span> <span class="special">:</span> <span class="keyword">public</span> <a class="link" href="reference/integral_constant.html" title="integral_constant">false_type</a><span class="special">{};</span> <span class="special">}</span> </pre> </div> <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> <td align="left"></td> <td align="right"><div class="copyright-footer">Copyright © 2000, 2006 Adobe Systems Inc, David Abrahams, Steve Cleary, Beman Dawes, Aleksey Gurtovoy, Howard Hinnant, Jesse Jones, Mat Marcus, Itay Maman, John Maddock, Alexander Nasonov, Thorsten Ottosen, Robert Ramey and Jeremy Siek<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>) </p> </div></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="category/function.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.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="intrinsics.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> </div> </body> </html>