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| <title>The MPL Reference Manual: apply_wrap</title> |
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| <table class="header"><tr class="header"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./apply.html" class="navigation-link">Prev</a> <a href="./unpack-args.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./apply.html" class="navigation-link">Back</a> <a href="./unpack-args.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./invocation.html" class="navigation-link">Up</a> <a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td> |
| <td class="header-group page-location"><a href="../refmanual.html" class="navigation-link">Front Page</a> / <a href="./metafunctions.html" class="navigation-link">Metafunctions</a> / <a href="./invocation.html" class="navigation-link">Invocation</a> / <a href="./apply-wrap.html" class="navigation-link">apply_wrap</a></td> |
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| <div class="section" id="apply-wrap"> |
| <h1><a class="toc-backref" href="./invocation.html#id1526">apply_wrap</a></h1> |
| <div class="section" id="id894"> |
| <h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3> |
| <pre class="literal-block"> |
| template< |
| typename F |
| > |
| struct apply_wrap0 |
| { |
| typedef <em>unspecified</em> type; |
| }; |
| |
| template< |
| typename F, typename A1 |
| > |
| struct apply_wrap1 |
| { |
| typedef <em>unspecified</em> type; |
| }; |
| |
| <em>...</em> |
| |
| template< |
| typename F, typename A1,<em>...</em> typename An |
| > |
| struct <a href="./apply-wrap.html" class="identifier">apply_wrap</a><em>n</em> |
| { |
| typedef <em>unspecified</em> type; |
| }; |
| </pre> |
| </div> |
| <div class="section" id="id895"> |
| <h3><a class="subsection-title" href="#description" name="description">Description</a></h3> |
| <p>Invokes a <a class="reference internal" href="./metafunction-class.html">Metafunction Class</a> <tt class="literal"><span class="pre">F</span></tt> with arguments <tt class="literal"><span class="pre">A1</span></tt>,... <tt class="literal"><span class="pre">An</span></tt>.</p> |
| <p>In essence, <tt class="literal"><span class="pre"><a href="./apply-wrap.html" class="identifier">apply_wrap</a></span></tt> forms are nothing more than syntactic wrappers around |
| <tt class="literal"><span class="pre">F::<a href="./apply.html" class="identifier">apply</a><A1,...</span> <span class="pre">An>::type</span></tt> / <tt class="literal"><span class="pre">F::<a href="./apply.html" class="identifier">apply</a>::type</span></tt> expressions (hence the name). |
| They provide a more concise notation and higher portability than their |
| underlaying constructs at the cost of an extra template instantiation.</p> |
| </div> |
| <div class="section" id="id896"> |
| <h3><a class="subsection-title" href="#header" name="header">Header</a></h3> |
| <pre class="literal-block"> |
| #include <<a href="../../../../boost/mpl/apply_wrap.hpp" class="header">boost/mpl/apply_wrap.hpp</a>> |
| </pre> |
| </div> |
| <div class="section" id="id897"> |
| <h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3> |
| <table border="1" class="docutils table"> |
| <colgroup> |
| <col width="15%" /> |
| <col width="36%" /> |
| <col width="48%" /> |
| </colgroup> |
| <thead valign="bottom"> |
| <tr><th class="head">Parameter</th> |
| <th class="head">Requirement</th> |
| <th class="head">Description</th> |
| </tr> |
| </thead> |
| <tbody valign="top"> |
| <tr><td><tt class="literal"><span class="pre">F</span></tt></td> |
| <td><a class="reference internal" href="./metafunction-class.html">Metafunction Class</a></td> |
| <td>A metafunction class to invoke.</td> |
| </tr> |
| <tr><td><tt class="literal"><span class="pre">A1</span></tt>,... <tt class="literal"><span class="pre">An</span></tt></td> |
| <td>Any type</td> |
| <td>Invocation arguments.</td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| <div class="section" id="id898"> |
| <h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3> |
| <p>For any <a class="reference internal" href="./metafunction-class.html">Metafunction Class</a> <tt class="literal"><span class="pre">f</span></tt> and arbitrary types <tt class="literal"><span class="pre">a1</span></tt>,... <tt class="literal"><span class="pre">an</span></tt>:</p> |
| <pre class="literal-block"> |
| typedef <a href="./apply-wrap.html" class="identifier">apply_wrap</a><em>n</em><f,a1,<em>...</em>an>::type t; |
| </pre> |
| <table class="docutils field-list" frame="void" rules="none"> |
| <col class="field-name" /> |
| <col class="field-body" /> |
| <tbody valign="top"> |
| <tr class="field"><th class="field-name">Return type:</th><td class="field-body">Any type.</td> |
| </tr> |
| <tr class="field"><th class="field-name">Semantics:</th><td class="field-body">If <tt class="literal"><span class="pre">n</span> <span class="pre">></span> <span class="pre">0</span></tt>, equivalent to <tt class="literal"><span class="pre">typedef</span> <span class="pre">f::<a href="./apply.html" class="identifier">apply</a><a1,...</span> <span class="pre">an>::type</span> <span class="pre">t;</span></tt>, |
| otherwise equivalent to either <tt class="literal"><span class="pre">typedef</span> <span class="pre">f::<a href="./apply.html" class="identifier">apply</a>::type</span> <span class="pre">t;</span></tt> or |
| <tt class="literal"><span class="pre">typedef</span> <span class="pre">f::<a href="./apply.html" class="identifier">apply</a><>::type</span> <span class="pre">t;</span></tt> depending on whether <tt class="literal"><span class="pre">f::<a href="./apply.html" class="identifier">apply</a></span></tt> is |
| a class or a class template.</td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| <div class="section" id="id899"> |
| <h3><a class="subsection-title" href="#example" name="example">Example</a></h3> |
| <pre class="literal-block"> |
| struct f0 |
| { |
| template< typename T = int > struct <a href="./apply.html" class="identifier">apply</a> |
| { |
| typedef char type; |
| }; |
| }; |
| |
| struct g0 |
| { |
| struct <a href="./apply.html" class="identifier">apply</a> { typedef char type; }; |
| }; |
| |
| struct f2 |
| { |
| template< typename T1, typename T2 > struct <a href="./apply.html" class="identifier">apply</a> |
| { |
| typedef T2 type; |
| }; |
| }; |
| |
| |
| typedef <a href="./apply-wrap.html" class="identifier">apply_wrap</a><tt class="literal"><span class="pre">0</span></tt>< f0 >::type r1; |
| typedef <a href="./apply-wrap.html" class="identifier">apply_wrap</a><tt class="literal"><span class="pre">0</span></tt>< g0 >::type r2; |
| typedef <a href="./apply-wrap.html" class="identifier">apply_wrap</a><tt class="literal"><span class="pre">2</span></tt>< f2,int,char >::type r3; |
| |
| <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( is_same<r1,char> )); |
| <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( is_same<r2,char> )); |
| <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( is_same<r3,char> )); |
| </pre> |
| </div> |
| <div class="section" id="id900"> |
| <h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3> |
| <p><a class="reference internal" href="./metafunctions.html">Metafunctions</a>, <a class="reference internal" href="./invocation.html">invocation</a>, <a class="reference internal" href="./apply.html">apply</a>, <a class="reference internal" href="./lambda.html">lambda</a>, <a class="reference internal" href="./quote.html">quote</a>, <a class="reference internal" href="./bind.html">bind</a>, <a class="reference internal" href="./protect.html">protect</a></p> |
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| <td><div class="copyright-footer"><div class="copyright">Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams</div> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
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