| <?xml version="1.0" encoding="utf-8" ?> |
| <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> |
| <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> |
| <head> |
| <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> |
| <meta name="generator" content="Docutils 0.7: http://docutils.sourceforge.net/" /> |
| <title>The MPL Reference Manual: arg</title> |
| <link rel="stylesheet" href="../style.css" type="text/css" /> |
| </head> |
| <body class="docframe refmanual"> |
| <table class="header"><tr class="header"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./quote.html" class="navigation-link">Prev</a> <a href="./protect.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./quote.html" class="navigation-link">Back</a> <a href="./protect.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./composition-and-argument-binding.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="./composition-and-argument-binding.html" class="navigation-link">Composition and Argument Binding</a> / <a href="./arg.html" class="navigation-link">arg</a></td> |
| </tr></table><div class="header-separator"></div> |
| <div class="section" id="arg"> |
| <h1><a class="toc-backref" href="./composition-and-argument-binding.html#id1533">arg</a></h1> |
| <div class="section" id="id946"> |
| <h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3> |
| <pre class="literal-block"> |
| template< int n > struct <a href="./arg.html" class="identifier">arg</a>; |
| |
| template<> struct <a href="./arg.html" class="identifier">arg</a><1> |
| { |
| template< typename A1,<em>...</em> typename A<em>n</em> = <em>unspecified</em> > |
| struct <a href="./apply.html" class="identifier">apply</a> |
| { |
| typedef A1 type; |
| }; |
| }; |
| |
| <em>...</em> |
| |
| template<> struct <a href="./arg.html" class="identifier">arg</a><<em>n</em>> |
| { |
| template< typename A1,<em>...</em> typename A<em>n</em> > |
| struct <a href="./apply.html" class="identifier">apply</a> |
| { |
| typedef A<em>n</em> type; |
| }; |
| }; |
| </pre> |
| </div> |
| <div class="section" id="id947"> |
| <h3><a class="subsection-title" href="#description" name="description">Description</a></h3> |
| <p><tt class="literal"><span class="pre"><a href="./arg.html" class="identifier">arg</a><n></span></tt> specialization is a <a class="reference internal" href="./metafunction-class.html">Metafunction Class</a> that return the <tt class="literal"><span class="pre">n</span></tt>th of its arguments.</p> |
| </div> |
| <div class="section" id="id948"> |
| <h3><a class="subsection-title" href="#header" name="header">Header</a></h3> |
| <pre class="literal-block"> |
| #include <<a href="../../../../boost/mpl/arg.hpp" class="header">boost/mpl/arg.hpp</a>> |
| </pre> |
| </div> |
| <div class="section" id="id949"> |
| <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">n</span></tt></td> |
| <td>An integral constant</td> |
| <td>A number of argument to return.</td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| <div class="section" id="id950"> |
| <h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3> |
| <p>For any integral constant <tt class="literal"><span class="pre">n</span></tt> in the range [1, <a class="reference internal" href="./limit-metafunction-arity.html">BOOST_MPL_LIMIT_METAFUNCTION_ARITY</a>] 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>< <a href="./arg.html" class="identifier">arg</a><<em>n</em>>,a1,<em>...</em>a<em>n</em> >::type x; |
| </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">A type.</td> |
| </tr> |
| <tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><tt class="literal"><span class="pre">x</span></tt> is identical to <tt class="literal"><span class="pre">an</span></tt>.</td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| <div class="section" id="id951"> |
| <h3><a class="subsection-title" href="#example" name="example">Example</a></h3> |
| <pre class="literal-block"> |
| typedef <a href="./apply-wrap.html" class="identifier">apply_wrap</a><tt class="literal"><span class="pre">5</span></tt>< <a href="./arg.html" class="identifier">arg</a><1>,bool,char,short,int,long >::type t1; |
| typedef <a href="./apply-wrap.html" class="identifier">apply_wrap</a><tt class="literal"><span class="pre">5</span></tt>< <a href="./arg.html" class="identifier">arg</a><3>,bool,char,short,int,long >::type t3; |
| |
| <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( is_same< t1, bool > )); |
| <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( is_same< t3, short > )); |
| </pre> |
| </div> |
| <div class="section" id="id952"> |
| <h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3> |
| <p><a class="reference internal" href="./composition-and-argument-binding.html">Composition and Argument Binding</a>, <a class="reference internal" href="./placeholders.html">Placeholders</a>, <a class="reference internal" href="./lambda.html">lambda</a>, <a class="reference internal" href="./bind.html">bind</a>, <a class="reference internal" href="./apply.html">apply</a>, <a class="reference internal" href="./apply-wrap.html">apply_wrap</a></p> |
| <!-- Metafunctions/Composition and Argument Binding//protect |60 --> |
| </div> |
| </div> |
| |
| <div class="footer-separator"></div> |
| <table class="footer"><tr class="footer"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./quote.html" class="navigation-link">Prev</a> <a href="./protect.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./quote.html" class="navigation-link">Back</a> <a href="./protect.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./composition-and-argument-binding.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><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 |
| file LICENSE_1_0.txt or copy at <a class="reference external" href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)</div></td></tr></table></body> |
| </html> |
