<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Struct template child</title> <link rel="stylesheet" href="../../../../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.78.1"> <link rel="home" href="../../../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> <link rel="up" href="../../../proto/reference.html#header.boost.proto.traits_hpp" title="Header <boost/proto/traits.hpp>"> <link rel="prev" href="child_c/result_T_idm45506973651728.html" title="Struct template result<This(Expr)>"> <link rel="next" href="child/result_T_idm45506973622592.html" title="Struct template result<This(Expr)>"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr> <td valign="top"><img alt="Boost C++ Libraries" 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alt="Next"></a> </div> <div class="refentry"> <a name="boost.proto.functional.child"></a><div class="titlepage"></div> <div class="refnamediv"> <h2><span class="refentrytitle">Struct template child</span></h2> <p>boost::proto::functional::child — A callable <a class="link" href="../../../PolymorphicFunctionObject.html" title="Concept PolymorphicFunctionObject">PolymorphicFunctionObject</a> that is equivalent to the <code class="computeroutput"><a class="link" href="../child_idm45506990961392.html" title="Function child">proto::child()</a></code> function.</p> </div> <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: <<a class="link" href="../../../proto/reference.html#header.boost.proto.traits_hpp" title="Header <boost/proto/traits.hpp>">boost/proto/traits.hpp</a>> </span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> N <span class="special">=</span> <span class="identifier">mpl</span><span class="special">::</span><span class="identifier">long_</span><span class="special"><</span><span class="number">0</span><span class="special">></span> <span class="special">></span> <span class="keyword">struct</span> <a class="link" href="child.html" title="Struct template child">child</a> <span class="special">:</span> <span class="keyword"></span> <a class="link" href="../callable.html" title="Struct callable">proto::callable</a> <span class="special">{</span> <span class="comment">// member classes/structs/unions</span> <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> This<span class="special">,</span> <span class="keyword">typename</span> <a class="link" href="../../../Expr.html" title="Concept Expr">Expr</a><span class="special">></span> <span class="keyword">struct</span> <a class="link" href="child/result_T_idm45506973622592.html" title="Struct template result<This(Expr)>">result</a><span class="special"><</span><span class="identifier">This</span><span class="special">(</span><span class="identifier">Expr</span><span class="special">)</span><span class="special">></span> <span class="special">:</span> <span class="keyword"></span> <a class="link" href="../result_of/child.html" title="Struct template child">proto::result_of::child</a>< Expr, N > <span class="special">{</span> <span class="special">}</span><span class="special">;</span> <span class="comment">// <a class="link" href="child.html#idm45506973618224-bb">public member functions</a></span> <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <a class="link" href="../../../Expr.html" title="Concept Expr">Expr</a><span class="special">></span> <span class="keyword">typename</span> <a class="link" href="../result_of/child.html" title="Struct template child">proto::result_of::child</a><span class="special"><</span> <span class="identifier">Expr</span> <span class="special">&</span><span class="special">,</span> <span class="identifier">N</span> <span class="special">></span><span class="special">::</span><span class="identifier">type</span> <a class="link" href="child.html#idm45506973617664-bb"><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span></a><span class="special">(</span><span class="identifier">Expr</span> <span class="special">&</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <a class="link" href="../../../Expr.html" title="Concept Expr">Expr</a><span class="special">></span> <span class="keyword">typename</span> <a class="link" href="../result_of/child.html" title="Struct template child">proto::result_of::child</a><span class="special"><</span> <span class="identifier">Expr</span> <span class="keyword">const</span> <span class="special">&</span><span class="special">,</span> <span class="identifier">N</span> <span class="special">></span><span class="special">::</span><span class="identifier">type</span> <a class="link" href="child.html#idm45506973605600-bb"><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span></a><span class="special">(</span><span class="identifier">Expr</span> <span class="keyword">const</span> <span class="special">&</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> <span class="special">}</span><span class="special">;</span></pre></div> <div class="refsect1"> <a name="idm45555180157312"></a><h2>Description</h2> <p> A callable <a class="link" href="../../../PolymorphicFunctionObject.html" title="Concept PolymorphicFunctionObject">PolymorphicFunctionObject</a> that is equivalent to the <code class="computeroutput"><a class="link" href="../child_idm45506990961392.html" title="Function child">proto::child()</a></code> function. <code class="computeroutput">N</code> is required to be an MPL Integral Constant. </p> <div class="refsect2"> <a name="idm45555180153488"></a><h3> <a name="idm45506973618224-bb"></a><code class="computeroutput">child</code> public member functions</h3> <div class="orderedlist"><ol class="orderedlist" type="1"> <li class="listitem"> <pre class="literallayout"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <a class="link" href="../../../Expr.html" title="Concept Expr">Expr</a><span class="special">></span> <span class="keyword">typename</span> <a class="link" href="../result_of/child.html" title="Struct template child">proto::result_of::child</a><span class="special"><</span> <span class="identifier">Expr</span> <span class="special">&</span><span class="special">,</span> <span class="identifier">N</span> <span class="special">></span><span class="special">::</span><span class="identifier">type</span> <a name="idm45506973617664-bb"></a><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><span class="identifier">Expr</span> <span class="special">&</span> expr<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre> <p> Return the <em class="replaceable"><code>N</code></em><sup>th</sup> child of the given expression. </p> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody> <tr> <td><p><span class="term">Parameters:</span></p></td> <td><div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody><tr> <td><p><span class="term"><code class="computeroutput">expr</code></span></p></td> <td><p>The expression node. </p></td> </tr></tbody> </table></div></td> </tr> <tr> <td><p><span class="term">Requires:</span></p></td> <td> <p> <code class="computeroutput"><a class="link" href="../is_expr.html" title="Struct template is_expr">proto::is_expr</a><Expr>::value</code> is <code class="computeroutput">true</code> </p> <p> <code class="computeroutput">N::value < Expr::proto_arity::value</code> </p> </td> </tr> <tr> <td><p><span class="term">Returns:</span></p></td> <td><p> <code class="computeroutput"><a class="link" href="../child_idm45506990961392.html" title="Function child">proto::child</a><N>(expr)</code> </p></td> </tr> <tr> <td><p><span class="term">Throws:</span></p></td> <td>Will not throw.</td> </tr> </tbody> </table></div> </li> <li class="listitem"> <pre class="literallayout"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <a class="link" href="../../../Expr.html" title="Concept Expr">Expr</a><span class="special">></span> <span class="keyword">typename</span> <a class="link" href="../result_of/child.html" title="Struct template child">proto::result_of::child</a><span class="special"><</span> <span class="identifier">Expr</span> <span class="keyword">const</span> <span class="special">&</span><span class="special">,</span> <span class="identifier">N</span> <span class="special">></span><span class="special">::</span><span class="identifier">type</span> <a name="idm45506973605600-bb"></a><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span><span class="special">(</span><span class="identifier">Expr</span> <span class="keyword">const</span> <span class="special">&</span> expr<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre> <p>This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. </p> </li> </ol></div> </div> </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"><div class="copyright-footer">Copyright © 2008 Eric Niebler<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>) </p> </div></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="child_c/result_T_idm45506973651728.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../../proto/reference.html#header.boost.proto.traits_hpp"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="child/result_T_idm45506973622592.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> </div> </body> </html>