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boost_fusion/doc/html/fusion/functional/adapters/fused_function_object.html
Tobias Schwinger 9df373af5f revises function object concepts and functional module documenation to reflect 
boost::result_of-based result computation


[SVN r38209]
2007-07-13 19:25:34 +00:00

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<div class="section" lang="en">
<div class="titlepage"><div><div><h4 class="title">
<a name="fusion.functional.adapters.fused_function_object"></a><a href="fused_function_object.html" title="fused_function_object">fused_function_object</a></h4></div></div></div>
<a name="fusion.functional.adapters.fused_function_object.description"></a><h5>
<a name="id1249910"></a>
<a href="fused_function_object.html#fusion.functional.adapters.fused_function_object.description">Description</a>
</h5>
<p>
An unary <a href="../concepts/poly.html" title=" Polymorphic Function
Object">Polymorphic Function
Object</a> adapter template for a <a href="../concepts/poly.html" title=" Polymorphic Function
Object">Polymorphic
Function Object</a> target function. It takes a <a href="../../sequences/concepts/forward_sequence.html" title="Forward
Sequence">Forward
Sequence</a> that contains the arguments for the target function.
</p>
<p>
The type of the target function is allowed to be const qualified or a reference.
Const qualification is preserved and propagated appropriately (in other
words, only const versions of <code class="literal">operator()</code> can be used
for an target function object that is const or, if the target function
object is held by value, the adapter is const).
</p>
<a name="fusion.functional.adapters.fused_function_object.header"></a><h5>
<a name="id1249979"></a>
<a href="fused_function_object.html#fusion.functional.adapters.fused_function_object.header">Header</a>
</h5>
<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">adapter</span><span class="special">/</span><span class="identifier">fused_function_object</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
</pre>
<a name="fusion.functional.adapters.fused_function_object.synopsis"></a><h5>
<a name="id1250074"></a>
<a href="fused_function_object.html#fusion.functional.adapters.fused_function_object.synopsis">Synopsis</a>
</h5>
<pre class="programlisting">
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Function</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">fused_function_object</span><span class="special">;</span>
</pre>
<a name="fusion.functional.adapters.fused_function_object.template_parameters"></a><h5>
<a name="id1250147"></a>
<a href="fused_function_object.html#fusion.functional.adapters.fused_function_object.template_parameters">Template
parameters</a>
</h5>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Parameter
</p>
</th>
<th>
<p>
Description
</p>
</th>
<th>
<p>
Default
</p>
</th>
</tr></thead>
<tbody><tr>
<td>
<p>
<code class="computeroutput"><span class="identifier">Function</span></code>
</p>
</td>
<td>
<p>
<a href="../concepts/poly.html" title=" Polymorphic Function
Object">Polymorphic Function
Object</a> type
</p>
</td>
<td>
<p>
</p>
</td>
</tr></tbody>
</table></div>
<a name="fusion.functional.adapters.fused_function_object.model_of"></a><h5>
<a name="id1250248"></a>
<a href="fused_function_object.html#fusion.functional.adapters.fused_function_object.model_of">Model
of</a>
</h5>
<div class="itemizedlist"><ul type="disc">
<li><a href="../concepts/poly.html" title=" Polymorphic Function
Object">Polymorphic Function
Object</a></li>
<li><a href="../concepts/def_callable.html" title=" Deferred
Callable Object">Deferred Callable
Object</a></li>
</ul></div>
<div class="variablelist">
<p class="title"><b>Notation</b></p>
<dl>
<dt><span class="term"><code class="computeroutput"><span class="identifier">R</span></code></span></dt>
<dd>
A possibly const qualified <a href="../concepts/poly.html" title=" Polymorphic Function
Object">Polymorphic
Function Object</a> type or reference type thereof
</dd>
<dt><span class="term"><code class="computeroutput"><span class="identifier">r</span></code></span></dt>
<dd>
An object convertible to <code class="computeroutput"><span class="identifier">R</span></code>
</dd>
<dt><span class="term"><code class="computeroutput"><span class="identifier">s</span></code></span></dt>
<dd>
A <a href="../../sequences.html" title="Sequences">Sequence</a> of arguments that
are accepted by <code class="computeroutput"><span class="identifier">r</span></code>
</dd>
<dt><span class="term"><code class="computeroutput"><span class="identifier">f</span></code></span></dt>
<dd>
An instance of <code class="computeroutput"><span class="identifier">fused</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span></code>
</dd>
</dl>
</div>
<a name="fusion.functional.adapters.fused_function_object.expression_semantics"></a><h5>
<a name="id1250433"></a>
<a href="fused_function_object.html#fusion.functional.adapters.fused_function_object.expression_semantics">Expression
Semantics</a>
</h5>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Expression
</p>
</th>
<th>
<p>
Semantics
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
<code class="computeroutput"><span class="identifier">fused_function_object</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;(</span><span class="identifier">r</span><span class="special">)</span></code>
</p>
</td>
<td>
<p>
Creates a fused function as described above, initializes the target
function with <code class="computeroutput"><span class="identifier">r</span></code>.
</p>
</td>
</tr>
<tr>
<td>
<p>
<code class="computeroutput"><span class="identifier">fused_function_object</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;()</span></code>
</p>
</td>
<td>
<p>
Creates a fused function as described above, attempts to use <code class="computeroutput"><span class="identifier">R</span></code>'s default constructor.
</p>
</td>
</tr>
<tr>
<td>
<p>
<code class="computeroutput"><span class="identifier">f</span><span class="special">(</span><span class="identifier">s</span><span class="special">)</span></code>
</p>
</td>
<td>
<p>
Calls <code class="computeroutput"><span class="identifier">r</span></code> with the
elements in <code class="computeroutput"><span class="identifier">s</span></code> as
its arguments.
</p>
</td>
</tr>
</tbody>
</table></div>
<a name="fusion.functional.adapters.fused_function_object.example"></a><h5>
<a name="id1250660"></a>
<a href="fused_function_object.html#fusion.functional.adapters.fused_function_object.example">Example</a>
</h5>
<pre class="programlisting">
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">SeqOfSeqs</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Func</span><span class="special">&gt;</span>
<span class="keyword">typename</span> <a href="../../algorithms/transformation/metafunctions/transform.html" title="transform"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">transform</span></code></a><span class="special">&lt;</span> <span class="identifier">zip_view</span><span class="special">&lt;</span><span class="identifier">SeqOfSeqs</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">,</span>
<span class="identifier">fused_function_object</span><span class="special">&lt;</span><span class="identifier">Func</span> <span class="keyword">const</span> <span class="special">&amp;&gt;</span> <span class="special">&gt;::</span><span class="identifier">type</span>
<span class="identifier">n_ary_transform</span><span class="special">(</span><span class="identifier">SeqOfSeqs</span> <span class="keyword">const</span> <span class="special">&amp;</span> <span class="identifier">s</span><span class="special">,</span> <span class="identifier">Func</span> <span class="keyword">const</span> <span class="special">&amp;</span> <span class="identifier">f</span><span class="special">)</span>
<span class="special">{</span>
<span class="keyword">return</span> <a href="../../algorithms/transformation/functions/transform.html" title="transform"><code class="computeroutput"><span class="identifier">transform</span></code></a><span class="special">(</span><span class="identifier">zip_view</span><span class="special">&lt;</span><span class="identifier">SeqOfSeqs</span><span class="special">&gt;(</span><span class="identifier">s</span><span class="special">),</span>
<span class="identifier">fused_function_object</span><span class="special">&lt;</span><span class="identifier">Func</span> <span class="keyword">const</span> <span class="special">&amp;&gt;(</span><span class="identifier">f</span><span class="special">));</span>
<span class="special">}</span>
<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>
<a href="../../sequences/containers/vector.html" title="vector"><code class="computeroutput"><span class="identifier">vector</span></code></a><span class="special">&lt;</span><span class="keyword">int</span><span class="special">,</span><span class="keyword">float</span><span class="special">&gt;</span> <span class="identifier">a</span><span class="special">(</span><span class="number">2</span><span class="special">,</span><span class="number">2.0f</span><span class="special">);</span>
<a href="../../sequences/containers/vector.html" title="vector"><code class="computeroutput"><span class="identifier">vector</span></code></a><span class="special">&lt;</span><span class="keyword">int</span><span class="special">,</span><span class="keyword">float</span><span class="special">&gt;</span> <span class="identifier">b</span><span class="special">(</span><span class="number">1</span><span class="special">,</span><span class="number">1.5f</span><span class="special">);</span>
<a href="../../sequences/containers/vector.html" title="vector"><code class="computeroutput"><span class="identifier">vector</span></code></a><span class="special">&lt;</span><span class="keyword">int</span><span class="special">,</span><span class="keyword">float</span><span class="special">&gt;</span> <span class="identifier">c</span><span class="special">(</span><span class="number">1</span><span class="special">,</span><span class="number">0.5f</span><span class="special">);</span>
<span class="identifier">assert</span><span class="special">(</span><span class="identifier">c</span> <span class="special">==</span> <span class="identifier">n_ary_transform</span><span class="special">(</span><a href="../../sequences/generation/functions/vector_tie.html" title="vector_tie"><code class="computeroutput"><span class="identifier">vector_tie</span></code></a><span class="special">(</span><span class="identifier">a</span><span class="special">,</span><span class="identifier">b</span><span class="special">),</span> <span class="identifier">sub</span><span class="special">()));</span>
<span class="special">}</span>
</pre>
<a name="fusion.functional.adapters.fused_function_object.see_also"></a><h5>
<a name="id1251594"></a>
<a href="fused_function_object.html#fusion.functional.adapters.fused_function_object.see_also">See
also</a>
</h5>
<div class="itemizedlist"><ul type="disc">
<li><a href="fused.html" title="fused"><code class="computeroutput"><span class="identifier">fused</span></code></a></li>
<li><a href="fused_procedure.html" title="fused_procedure"><code class="computeroutput"><span class="identifier">fused_procedure</span></code></a></li>
<li><a href="../invocation/functions/invoke_fobj.html" title="
invoke_function_object"><code class="computeroutput"><span class="identifier">invoke_function_object</span></code></a></li>
<li><a href="../../support/deduce.html" title="deduce"><code class="computeroutput"><span class="identifier">deduce</span></code></a></li>
</ul></div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><small>Copyright © 2001-2007 Joel de Guzman, Dan Marsden, Tobias
Schwinger</small></td>
</tr></table>
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