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          invoke_function_object</title>
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<div class="titlepage"><div><div><h5 class="title">
<a name="fusion.functional.invocation.functions.invoke_fobj"></a><a href="invoke_fobj.html" title="
          invoke_function_object">
          invoke_function_object</a></h5></div></div></div>
<a name="fusion.functional.invocation.functions.invoke_fobj.description"></a><h6>
<a name="id1245192"></a>
            <a href="invoke_fobj.html#fusion.functional.invocation.functions.invoke_fobj.description">Description</a>
          </h6>
<p>
            Calls a <a href="../../concepts/poly.html" title=" Polymorphic Function
        Object">Polymorphic Function
            Object</a> with the arguments from a <a href="../../../sequences.html" title="Sequences">Sequence</a>.
          </p>
<p>
            The first template parameter can be specialized explicitly to avoid copying
            and/or to control the const qualification of a function object.
          </p>
<a name="fusion.functional.invocation.functions.invoke_fobj.synopsis"></a><h6>
<a name="id1245241"></a>
            <a href="invoke_fobj.html#fusion.functional.invocation.functions.invoke_fobj.synopsis">Synopsis</a>
          </h6>
<pre class="programlisting">
<span class="keyword">template</span><span class="special">&lt;</span>
    <span class="keyword">typename</span> <span class="identifier">Function</span><span class="special">,</span> 
    <span class="keyword">class</span> <span class="identifier">Sequence</span>
    <span class="special">&gt;</span>
<span class="keyword">typename</span> <a href="../metafunctions/invoke_fobj.html" title="
          invoke_function_object"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">invoke_function_object</span></code></a><span class="special">&lt;</span><span class="identifier">Function</span><span class="special">,</span> <span class="identifier">Sequence</span><span class="special">&gt;::</span><span class="identifier">type</span>
<span class="identifier">invoke_function_object</span><span class="special">(</span><span class="identifier">Function</span> <span class="identifier">f</span><span class="special">,</span> <span class="identifier">Sequence</span> <span class="special">&amp;</span> <span class="identifier">s</span><span class="special">);</span>

<span class="keyword">template</span><span class="special">&lt;</span>
    <span class="keyword">typename</span> <span class="identifier">Function</span><span class="special">,</span> 
    <span class="keyword">class</span> <span class="identifier">Sequence</span>
    <span class="special">&gt;</span>
<span class="keyword">typename</span> <a href="../metafunctions/invoke_fobj.html" title="
          invoke_function_object"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">invoke_function_object</span></code></a><span class="special">&lt;</span><span class="identifier">Function</span><span class="special">,</span> <span class="identifier">Sequence</span> <span class="keyword">const</span><span class="special">&gt;::</span><span class="identifier">type</span>
<span class="identifier">invoke_function_object</span><span class="special">(</span><span class="identifier">Function</span> <span class="identifier">f</span><span class="special">,</span> <span class="identifier">Sequence</span> <span class="keyword">const</span> <span class="special">&amp;</span> <span class="identifier">s</span><span class="special">);</span>
</pre>
<a name="fusion.functional.invocation.functions.invoke_fobj.parameters"></a><h6>
<a name="id1245575"></a>
            <a href="invoke_fobj.html#fusion.functional.invocation.functions.invoke_fobj.parameters">Parameters</a>
          </h6>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
                  <p>
                    Parameter
                  </p>
                  </th>
<th>
                  <p>
                    Requirement
                  </p>
                  </th>
<th>
                  <p>
                    Description
                  </p>
                  </th>
</tr></thead>
<tbody>
<tr>
<td>
                  <p>
                    <code class="computeroutput"><span class="identifier">f</span></code>
                  </p>
                  </td>
<td>
                  <p>
                    Model of <a href="../../concepts/poly.html" title=" Polymorphic Function
        Object">Polymorphic
                    Function Object</a>
                  </p>
                  </td>
<td>
                  <p>
                    The function object to call.
                  </p>
                  </td>
</tr>
<tr>
<td>
                  <p>
                    <code class="computeroutput"><span class="identifier">s</span></code>
                  </p>
                  </td>
<td>
                  <p>
                    Model of <a href="../../../sequences/concepts/forward_sequence.html" title="Forward
        Sequence">Forward
                    Sequence</a>
                  </p>
                  </td>
<td>
                  <p>
                    The arguments.
                  </p>
                  </td>
</tr>
</tbody>
</table></div>
<a name="fusion.functional.invocation.functions.invoke_fobj.expression_semantics"></a><h6>
<a name="id1245721"></a>
            <a href="invoke_fobj.html#fusion.functional.invocation.functions.invoke_fobj.expression_semantics">Expression
            Semantics</a>
          </h6>
<pre class="programlisting">
<span class="identifier">invoke_function_object</span><span class="special">(</span><span class="identifier">f</span><span class="special">,</span><span class="identifier">s</span><span class="special">);</span>
</pre>
<p>
            <span class="bold"><strong>Return type</strong></span>: Return type of <code class="computeroutput"><span class="identifier">f</span></code> when invoked with the elements in
            <code class="computeroutput"><span class="identifier">s</span></code> as its arguments.
          </p>
<p>
            <span class="bold"><strong>Semantics</strong></span>: Invokes <code class="computeroutput"><span class="identifier">f</span></code>
            with the elements in <code class="computeroutput"><span class="identifier">s</span></code>
            as arguments and returns the result of the call expression.
          </p>
<a name="fusion.functional.invocation.functions.invoke_fobj.header"></a><h6>
<a name="id1245840"></a>
            <a href="invoke_fobj.html#fusion.functional.invocation.functions.invoke_fobj.header">Header</a>
          </h6>
<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">functional</span><span class="special">/</span><span class="identifier">invocation</span><span class="special">/</span><span class="identifier">invoke_function_object</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
</pre>
<a name="fusion.functional.invocation.functions.invoke_fobj.example"></a><h6>
<a name="id1245933"></a>
            <a href="invoke_fobj.html#fusion.functional.invocation.functions.invoke_fobj.example">Example</a>
          </h6>
<pre class="programlisting">
<span class="keyword">struct</span> <span class="identifier">sub</span>
<span class="special">{</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Sig</span><span class="special">&gt;</span>
    <span class="keyword">struct</span> <span class="identifier">result</span><span class="special">;</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Self</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
    <span class="keyword">struct</span> <span class="identifier">result</span><span class="special">&lt;</span> <span class="identifier">Self</span><span class="special">(</span><span class="identifier">T</span><span class="special">,</span><span class="identifier">T</span><span class="special">)</span> <span class="special">&gt;</span> 
    <span class="special">{</span> <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">remove_reference</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">type</span> <span class="identifier">type</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">T</span> <span class="keyword">operator</span><span class="special">()(</span><span class="identifier">T</span> <span class="identifier">lhs</span><span class="special">,</span> <span class="identifier">T</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="keyword">const</span>
    <span class="special">{</span>
        <span class="keyword">return</span> <span class="identifier">lhs</span> <span class="special">-</span> <span class="identifier">rhs</span><span class="special">;</span>
    <span class="special">}</span>
<span class="special">};</span>

<span class="keyword">void</span> <span class="identifier">try_it</span><span class="special">()</span>
<span class="special">{</span>
    <span class="identifier">sub</span> <span class="identifier">f</span><span class="special">;</span>
    <span class="identifier">assert</span><span class="special">(</span><span class="identifier">f</span><span class="special">(</span><span class="number">2</span><span class="special">,</span><span class="number">1</span><span class="special">)</span> <span class="special">==</span> <span class="identifier">invoke_function_object</span><span class="special">(</span><span class="identifier">f</span><span class="special">,</span><a href="../../../sequences/generation/functions/make_vector.html" title="make_vector"><code class="computeroutput"><span class="identifier">make_vector</span></code></a><span class="special">(</span><span class="number">2</span><span class="special">,</span><span class="number">1</span><span class="special">)));</span>
<span class="special">}</span>
</pre>
<a name="fusion.functional.invocation.functions.invoke_fobj.see_also"></a><h6>
<a name="id1246418"></a>
            <a href="invoke_fobj.html#fusion.functional.invocation.functions.invoke_fobj.see_also">See
            also</a>
          </h6>
<div class="itemizedlist"><ul type="disc">
<li><a href="invoke.html" title="invoke"><code class="computeroutput"><span class="identifier">invoke</span></code></a></li>
<li><a href="invoke_proc.html" title="
          invoke_procedure"><code class="computeroutput"><span class="identifier">invoke_procedure</span></code></a></li>
<li><a href="../metafunctions/invoke_fobj.html" title="
          invoke_function_object"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">invoke_function_object</span></code></a></li>
<li><a href="../../adapters/fused_function_object.html" title="fused_function_object"><code class="computeroutput"><span class="identifier">fused_function_object</span></code></a></li>
</ul></div>
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