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| <h2><span class="refentrytitle">Macro BOOST_TTI_TRAIT_MEMBER_TYPE</span></h2> |
| <p>BOOST_TTI_TRAIT_MEMBER_TYPE — Expands to a metafunction whose typedef 'type' is either the named type or a marker type. </p> |
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| <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> |
| <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: <<a class="link" href="header/boost/tti/member_type_hpp.html" title="Header <boost/tti/member_type.hpp>">boost/tti/member_type.hpp</a>> |
| |
| </span>BOOST_TTI_TRAIT_MEMBER_TYPE(trait, name)</pre></div> |
| <div class="refsect1"> |
| <a name="idp103180800"></a><h2>Description</h2> |
| <p>trait = the name of the metafunction within the tti namespace.</p> |
| <p>name = the name of the inner type.</p> |
| <p>generates a metafunction called "trait" where 'trait' is the macro parameter. template<class BOOST_TTI_TP_T,class BOOST_TTI_TP_MARKER_TYPE = boost::tti::detail::notype> |
| struct trait |
| { |
| typedef unspecified type; |
| |
| typedef BOOST_TTI_TP_MARKER_TYPE boost_tti_marker_type; |
| }; |
| |
| The metafunction types and return: |
| |
| BOOST_TTI_TP_T = the enclosing type. |
| BOOST_TTI_TP_MARKER_TYPE = (optional) a type to use as the marker type. |
| defaults to the internal boost::tti::detail::notype. |
| |
| returns = 'type' is the inner type of 'name' if the inner type exists |
| within the enclosing type, else 'type' is a marker type. |
| if the end-user does not specify a marker type then |
| an internal boost::tti::detail::notype marker type is used. |
| |
| The metafunction also encapsulates the type of the marker type as |
| a nested 'boost_tti_marker_type'. |
| </p> |
| <p>The purpose of this macro is to encapsulate the 'name' type as the typedef 'type' of a metafunction, but only if it exists within the enclosing type. This allows for an evaluation of inner type existence, without generating a compiler error, which can be used by other metafunctions in this library. </p> |
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| <td align="right"><div class="copyright-footer">Copyright © 2011-2013 Tropic Software |
| East Inc<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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