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| <div class="titlepage"><div><div><h5 class="title"> |
| <a name="fusion.sequence.intrinsic.metafunctions.at_key"></a><a class="link" href="at_key.html" title="at_key">at_key</a> |
| </h5></div></div></div> |
| <a name="fusion.sequence.intrinsic.metafunctions.at_key.description"></a><h6> |
| <a name="id897637"></a> |
| <a class="link" href="at_key.html#fusion.sequence.intrinsic.metafunctions.at_key.description">Description</a> |
| </h6> |
| <p> |
| Returns the result type of <a class="link" href="../functions/at_key.html" title="at_key"><code class="computeroutput"><span class="identifier">at_key</span></code></a><sup>[<a name="id897660" href="#ftn.id897660" class="footnote">8</a>]</sup>. |
| </p> |
| <a name="fusion.sequence.intrinsic.metafunctions.at_key.synopsis"></a><h6> |
| <a name="id897730"></a> |
| <a class="link" href="at_key.html#fusion.sequence.intrinsic.metafunctions.at_key.synopsis">Synopsis</a> |
| </h6> |
| <pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> |
| <span class="keyword">typename</span> <span class="identifier">Seq</span><span class="special">,</span> |
| <span class="keyword">typename</span> <span class="identifier">Key</span><span class="special">></span> |
| <span class="keyword">struct</span> <span class="identifier">at_key</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> |
| </pre> |
| <div class="table"> |
| <a name="id897814"></a><p class="title"><b>Table 1.34. Parameters</b></p> |
| <div class="table-contents"><table class="table" summary="Parameters"> |
| <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">Seq</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| A model of <a class="link" href="../../concepts/forward_sequence.html" title="Forward Sequence">Forward |
| Sequence</a> |
| </p> |
| </td> |
| <td> |
| <p> |
| Argument sequence |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="identifier">Key</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Any type |
| </p> |
| </td> |
| <td> |
| <p> |
| Key type |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| </div> |
| <br class="table-break"><a name="fusion.sequence.intrinsic.metafunctions.at_key.expression_semantics"></a><h6> |
| <a name="id897934"></a> |
| <a class="link" href="at_key.html#fusion.sequence.intrinsic.metafunctions.at_key.expression_semantics">Expression |
| Semantics</a> |
| </h6> |
| <pre class="programlisting"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">at_key</span><span class="special"><</span><span class="identifier">Seq</span><span class="special">,</span> <span class="identifier">Key</span><span class="special">>::</span><span class="identifier">type</span> |
| </pre> |
| <p> |
| <span class="bold"><strong>Return type</strong></span>: Any type. |
| </p> |
| <p> |
| <span class="bold"><strong>Semantics</strong></span>: Returns the result of using |
| <a class="link" href="../functions/at_key.html" title="at_key"><code class="computeroutput"><span class="identifier">at_key</span></code></a> to access the element |
| with key type <code class="computeroutput"><span class="identifier">Key</span></code> in |
| <code class="computeroutput"><span class="identifier">Seq</span></code>. |
| </p> |
| <a name="fusion.sequence.intrinsic.metafunctions.at_key.header"></a><h6> |
| <a name="id898027"></a> |
| <a class="link" href="at_key.html#fusion.sequence.intrinsic.metafunctions.at_key.header">Header</a> |
| </h6> |
| <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">fusion</span><span class="special">/</span><span class="identifier">sequence</span><span class="special">/</span><span class="identifier">intrinsic</span><span class="special">/</span><span class="identifier">at_key</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">fusion</span><span class="special">/</span><span class="identifier">include</span><span class="special">/</span><span class="identifier">at_key</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| </pre> |
| <a name="fusion.sequence.intrinsic.metafunctions.at_key.example"></a><h6> |
| <a name="id898142"></a> |
| <a class="link" href="at_key.html#fusion.sequence.intrinsic.metafunctions.at_key.example">Example</a> |
| </h6> |
| <pre class="programlisting"><span class="keyword">typedef</span> <a class="link" href="../../../container/map.html" title="map"><code class="computeroutput"><span class="identifier">map</span></code></a><span class="special"><</span><a class="link" href="../../../support/pair.html" title="pair"><code class="computeroutput"><span class="identifier">pair</span></code></a><span class="special"><</span><span class="keyword">int</span><span class="special">,</span> <span class="keyword">char</span><span class="special">>,</span> <a class="link" href="../../../support/pair.html" title="pair"><code class="computeroutput"><span class="identifier">pair</span></code></a><span class="special"><</span><span class="keyword">char</span><span class="special">,</span> <span class="keyword">char</span><span class="special">>,</span> <a class="link" href="../../../support/pair.html" title="pair"><code class="computeroutput"><span class="identifier">pair</span></code></a><span class="special"><</span><span class="keyword">double</span><span class="special">,</span> <span class="keyword">char</span><span class="special">></span> <span class="special">></span> <span class="identifier">mymap</span><span class="special">;</span> |
| <span class="identifier">BOOST_MPL_ASSERT</span><span class="special">((</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_same</span><span class="special"><</span><a class="link" href="at_key.html" title="at_key"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">at_key</span></code></a><span class="special"><</span><span class="identifier">mymap</span><span class="special">,</span> <span class="keyword">int</span><span class="special">>::</span><span class="identifier">type</span><span class="special">,</span> <span class="keyword">char</span><span class="special">&>));</span> |
| </pre> |
| <div class="footnotes"> |
| <br><hr width="100" align="left"> |
| <div class="footnote"><p><sup>[<a name="ftn.id897660" href="#id897660" class="para">8</a>] </sup> |
| <a class="link" href="at_key.html" title="at_key"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">at_key</span></code></a> reflects the actual |
| return type of the function <a class="link" href="../functions/at_key.html" title="at_key"><code class="computeroutput"><span class="identifier">at_key</span></code></a>. <span class="underline">_sequence</span>_s |
| typically return references to its elements via the <a class="link" href="../functions/at_key.html" title="at_key"><code class="computeroutput"><span class="identifier">at_key</span></code></a> function. If you want |
| to get the actual element type, use <a class="link" href="value_at_key.html" title="value_at_key"><code class="computeroutput"><span class="identifier">result_of</span><span class="special">::</span><span class="identifier">value_at_key</span></code></a> |
| </p></div> |
| </div> |
| </div> |
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| <td align="left"></td> |
| <td align="right"><div class="copyright-footer">Copyright © 2001-2007 Joel de Guzman, Dan Marsden, Tobias |
| Schwinger<p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) |
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