hen the
      reason it exists in the library.
    </p>
<p>
      The functionality is a metafunction created by the macro <code class="computeroutput"><a class="link" href="../BOOST_TTI_MEMBER_TYPE.html" title="Macro BOOST_TTI_MEMBER_TYPE">BOOST_TTI_MEMBER_TYPE</a></code>.
      The macro takes a single parameter, which is the name of a nested type. We
      will call this our 'named type'. The macro generates a metafunction called
      <code class="computeroutput"><span class="identifier">member_type_</s