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<h2><span class="refentrytitle">Macro BOOST_TTI_HAS_MEMBER_DATA</span></h2>
<p>BOOST_TTI_HAS_MEMBER_DATA — A macro which expands to a metafunction which tests whether a member data with a particular name and type exists. </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: &lt;<a class="link" href="header/boost/tti/has_member_data_hpp.html" title="Header &lt;boost/tti/has_member_data.hpp&gt;">boost/tti/has_member_data.hpp</a>&gt;
</span>BOOST_TTI_HAS_MEMBER_DATA(name)</pre></div>
<div class="refsect1">
<a name="idm46191514032272"></a><h2>Description</h2>
<p>BOOST_TTI_HAS_MEMBER_DATA is a macro which expands to a metafunction. The metafunction tests whether member data with a particular name and type exists. The macro takes the form of BOOST_TTI_HAS_MEMBER_DATA(name) where</p>
<p>name = the name of the inner member.</p>
<p>BOOST_TTI_HAS_MEMBER_DATA generates a metafunction called "has_member_data_name" where 'name' is the macro parameter.</p>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">BOOST_TTI_TP_ET</span><span class="special">,</span><span class="keyword">class</span> <span class="identifier">BOOST_TTI_TP_TYPE</span><span class="special">&gt;</span>
<span class="keyword">struct</span> <span class="identifier">has_member_data_</span><span class="char">'name'</span>
<span class="special">{</span>
<span class="keyword">static</span> <span class="keyword">const</span> <span class="identifier">value</span> <span class="special">=</span> <span class="identifier">unspecified</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="identifier">mpl</span><span class="special">::</span><span class="identifier">bool_</span><span class="special">&lt;</span><span class="keyword">true</span><span class="special">-</span><span class="identifier">or</span><span class="special">-</span><span class="keyword">false</span><span class="special">&gt;</span> <span class="identifier">type</span><span class="special">;</span>
<span class="special">}</span><span class="special">;</span>
<span class="identifier">The</span> <span class="identifier">metafunction</span> <span class="identifier">types</span> <span class="identifier">and</span> <span class="keyword">return</span><span class="special">:</span>
<span class="identifier">BOOST_TTI_TP_ET</span> <span class="special">=</span> <span class="identifier">the</span> <span class="identifier">enclosing</span> <span class="identifier">type</span> <span class="identifier">in</span> <span class="identifier">which</span> <span class="identifier">to</span> <span class="identifier">look</span> <span class="keyword">for</span> <span class="identifier">our</span> <span class="char">'name'</span><span class="special">.</span>
<span class="identifier">The</span> <span class="identifier">enclosing</span> <span class="identifier">type</span> <span class="identifier">can</span> <span class="identifier">be</span> <span class="identifier">a</span> <span class="keyword">class</span><span class="special">,</span> <span class="keyword">struct</span><span class="special">,</span> <span class="identifier">or</span> <span class="keyword">union</span><span class="special">.</span>
<span class="identifier">OR</span>
<span class="identifier">The</span> <span class="identifier">type</span> <span class="identifier">of</span> <span class="identifier">the</span> <span class="identifier">member</span> <span class="identifier">data</span> <span class="identifier">in</span> <span class="identifier">the</span> <span class="identifier">form</span> <span class="identifier">of</span> <span class="identifier">a</span> <span class="identifier">pointer</span>
<span class="identifier">to</span> <span class="identifier">member</span> <span class="identifier">data</span><span class="special">.</span>
<span class="identifier">BOOST_TTI_TP_TYPE</span> <span class="special">=</span> <span class="special">(</span><span class="identifier">optional</span><span class="special">)</span> <span class="identifier">The</span> <span class="identifier">type</span> <span class="identifier">of</span> <span class="identifier">the</span> <span class="identifier">member</span> <span class="identifier">data</span> <span class="keyword">if</span> <span class="identifier">the</span> <span class="identifier">first</span>
<span class="identifier">parameter</span> <span class="identifier">is</span> <span class="identifier">the</span> <span class="identifier">enclosing</span> <span class="identifier">type</span><span class="special">.</span>
<span class="identifier">returns</span> <span class="special">=</span> <span class="char">'value'</span> <span class="identifier">is</span> <span class="keyword">true</span> <span class="keyword">if</span> <span class="identifier">the</span> <span class="char">'name'</span> <span class="identifier">exists</span><span class="special">,</span> <span class="identifier">with</span> <span class="identifier">the</span> <span class="identifier">correct</span> <span class="identifier">data</span> <span class="identifier">type</span><span class="special">,</span>
<span class="identifier">otherwise</span> <span class="char">'value'</span> <span class="identifier">is</span> <span class="keyword">false</span><span class="special">.</span>
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