1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html> 3<head> 4<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 5<title>Struct template is_aggregate</title> 6<link rel="stylesheet" href="../../../../doc/src/boostbook.css" type="text/css"> 7<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 8<link rel="home" href="../../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> 9<link rel="up" href="../../proto/reference.html#header.boost.proto.traits_hpp" title="Header <boost/proto/traits.hpp>"> 10<link rel="prev" href="is_transform.html" title="Struct template is_transform"> 11<link rel="next" href="terminal.html" title="Struct template terminal"> 12</head> 13<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 14<table cellpadding="2" width="100%"><tr> 15<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../boost.png"></td> 16<td align="center"><a href="../../../../index.html">Home</a></td> 17<td align="center"><a href="../../../../libs/libraries.htm">Libraries</a></td> 18<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 19<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 20<td align="center"><a href="../../../../more/index.htm">More</a></td> 21</tr></table> 22<hr> 23<div class="spirit-nav"> 24<a accesskey="p" href="is_transform.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="terminal.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 25</div> 26<div class="refentry"> 27<a name="boost.proto.is_aggregate"></a><div class="titlepage"></div> 28<div class="refnamediv"> 29<h2><span class="refentrytitle">Struct template is_aggregate</span></h2> 30<p>boost::proto::is_aggregate — A Boolean metafunction that indicates whether a type requires aggregate initialization. </p> 31</div> 32<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> 33<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>> 34 35</span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> T<span class="special">></span> 36<span class="keyword">struct</span> <a class="link" href="is_aggregate.html" title="Struct template is_aggregate">is_aggregate</a> <span class="special">:</span> <span class="keyword"></span> mpl::bool_<<em class="replaceable"><code>true-or-false</code></em>> <span class="special">{</span> 37<span class="special">}</span><span class="special">;</span></pre></div> 38<div class="refsect1"> 39<a name="id-1.3.33.5.41.20.4"></a><h2>Description</h2> 40<p> 41 <code class="computeroutput">proto::is_aggregate<></code> is used by the 42 <code class="computeroutput"><a class="link" href="make.html" title="Struct template make">proto::make<></a></code> transform to determine how 43 to construct an object of some type <code class="computeroutput">T</code>, given some initialization arguments 44 <code class="computeroutput">a<sub>0</sub>,...a<sub>n</sub></code>. 45 If <code class="computeroutput">proto::is_aggregate<T>::value</code> is <code class="computeroutput">true</code>, 46 then an object of type <code class="computeroutput">T</code> will be initialized as 47 <code class="computeroutput">T t = {a<sub>0</sub>,...a<sub>n</sub>};</code>. 48 Otherwise, it will be initialized as 49 <code class="computeroutput">T t(a<sub>0</sub>,...a<sub>n</sub>)</code>. 50 </p> 51<p> 52 Note: <code class="computeroutput"><a class="link" href="expr.html" title="Struct template expr">proto::expr<></a></code> and 53 <code class="computeroutput"><a class="link" href="basic_expr.html" title="Struct template basic_expr">proto::basic_expr<></a></code>are aggregates. 54 </p> 55</div> 56</div> 57<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 58<td align="left"></td> 59<td align="right"><div class="copyright-footer">Copyright © 2008 Eric Niebler<p> 60 Distributed under the Boost Software License, Version 1.0. (See accompanying 61 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>) 62 </p> 63</div></td> 64</tr></table> 65<hr> 66<div class="spirit-nav"> 67<a accesskey="p" href="is_transform.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="terminal.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 68</div> 69</body> 70</html> 71
