boost_fusion/doc/html/fusion/support/deduce.html

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<div class="titlepage"><div><div><h3 class="title">
<a name="fusion.support.deduce"></a><a href="deduce.html" title="deduce">deduce</a></h3></div></div></div>
<a name="fusion.support.deduce.description"></a><h4>
<a name="id930492"></a>
        <a href="deduce.html#fusion.support.deduce.description">Description</a>
      </h4>
<p>
        Metafunction to apply <a href="../notes.html#fusion.notes.element_conversion"><span class="emphasis"><em>element
        conversion</em></span></a> to the full argument type.
      </p>
<p>
        It removes references to <code class="computeroutput"><span class="keyword">const</span></code>,
        references to array types are kept, even if the array is <code class="computeroutput"><span class="keyword">const</span></code>.
        Reference wrappers are removed (see <a href="../notes.html#fusion.notes.boost__ref"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">ref</span></code></a>).
      </p>
<a name="fusion.support.deduce.header"></a><h4>
<a name="id930578"></a>
        <a href="deduce.html#fusion.support.deduce.header">Header</a>
      </h4>
<pre class="programlisting">
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">fusion</span><span class="special">/</span><span class="identifier">support</span><span class="special">/</span><span class="identifier">deduce</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
</pre>
<a name="fusion.support.deduce.synopsis"></a><h4>
<a name="id930660"></a>
        <a href="deduce.html#fusion.support.deduce.synopsis">Synopsis</a>
      </h4>
<pre class="programlisting">
<span class="keyword">namespace</span> <span class="identifier">traits</span>
<span class="special">{</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span> 
    <span class="keyword">struct</span> <span class="identifier">deduce</span>
    <span class="special">{</span>
        <span class="keyword">typedef</span> <span class="emphasis"><em>unspecified</em></span> <span class="identifier">type</span><span class="special">;</span>
    <span class="special">};</span>
<span class="special">}</span>
</pre>
<a name="fusion.support.deduce.example"></a><h4>
<a name="id930776"></a>
        <a href="deduce.html#fusion.support.deduce.example">Example</a>
      </h4>
<pre class="programlisting">
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
<span class="keyword">struct</span> <span class="identifier">holder</span>
<span class="special">{</span>
    <span class="keyword">typename</span> <span class="identifier">traits</span><span class="special">::</span><span class="identifier">deduce</span><span class="special">&lt;</span><span class="identifier">T</span> <span class="keyword">const</span> <span class="special">&amp;&gt;::</span><span class="identifier">type</span> <span class="identifier">element</span><span class="special">;</span>

    <span class="identifier">holder</span><span class="special">(</span><span class="identifier">T</span> <span class="keyword">const</span> <span class="special">&amp;</span> <span class="identifier">a</span><span class="special">)</span>
      <span class="special">:</span> <span class="identifier">element</span><span class="special">(</span><span class="identifier">a</span><span class="special">)</span>
    <span class="special">{</span> <span class="special">}</span>
<span class="special">};</span>

<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
<span class="identifier">holder</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">make_holder</span><span class="special">(</span><span class="identifier">T</span> <span class="keyword">const</span> <span class="special">&amp;</span> <span class="identifier">a</span><span class="special">)</span>
<span class="special">{</span>
    <span class="keyword">return</span> <span class="identifier">holder</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;(</span><span class="identifier">a</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<a name="fusion.support.deduce.see_also"></a><h4>
<a name="id931097"></a>
        <a href="deduce.html#fusion.support.deduce.see_also">See also</a>
      </h4>
<div class="itemizedlist"><ul type="disc"><li><a href="deduce_sequence.html" title="deduce_sequence"><code class="computeroutput"><span class="identifier">deduce_sequence</span></code></a></li></ul></div>
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