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 data_type</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.transform.env_hpp" title="Header <boost/proto/transform/env.hpp>"> 10<link rel="prev" href="is_env.html" title="Struct template is_env"> 11<link rel="next" href="data.html" title="Global data"> 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 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class="refnamediv"> 29<h2><span class="refentrytitle">Struct data_type</span></h2> 30<p>boost::proto::data_type — 31 The type of <code class="computeroutput"><a class="link" href="data.html" title="Global data">proto::data</a></code>, a key for use when creating 32 a transform environment that associates a piece of data with this type. 33 </p> 34</div> 35<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> 36<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.transform.env_hpp" title="Header <boost/proto/transform/env.hpp>">boost/proto/transform/env.hpp</a>> 37 38</span> 39<span class="keyword">struct</span> <a class="link" href="data_type.html" title="Struct data_type">data_type</a> <span class="special">{</span> 40 41 <span class="comment">// <a class="link" href="data_type.html#id-1_3_33_5_44_1_1_5_3-bb">public member functions</a></span> 42 <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> Value<span class="special">></span> <a class="link" href="env.html" title="Struct template env">env</a><span class="special"><</span><span class="identifier">data_type</span><span class="special">,</span> <em class="replaceable"><code><span class="identifier">see</span><span class="special">-</span><span class="identifier">below</span></code></em><span class="special">></span> <a class="link" href="data_type.html#id-1_3_33_5_44_1_1_5_3_1_1-bb"><span class="keyword">operator</span><span class="special">=</span></a><span class="special">(</span><span class="identifier">Value</span> <span class="special">&</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> 43 <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> Value<span class="special">></span> 44 <a class="link" href="env.html" title="Struct template env">env</a><span class="special"><</span><span class="identifier">data_type</span><span class="special">,</span> <em class="replaceable"><code><span class="identifier">see</span><span class="special">-</span><span class="identifier">below</span></code></em><span class="special">></span> <a class="link" href="data_type.html#id-1_3_33_5_44_1_1_5_3_1_2-bb"><span class="keyword">operator</span><span class="special">=</span></a><span class="special">(</span><span class="identifier">Value</span> <span class="keyword">const</span> <span class="special">&</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> 45<span class="special">}</span><span class="special">;</span></pre></div> 46<div class="refsect1"> 47<a name="id-1.3.33.5.46.14.4"></a><h2>Description</h2> 48<p> 49 The <code class="computeroutput">proto::data_type</code> type, along with the <code class="computeroutput"><a class="link" href="data.html" title="Global data">proto::data</a></code> 50 global, are declared using the <code class="computeroutput"><a class="link" href="../../BOOST_PROTO_DEFINE_ENV_VAR.html" title="Macro BOOST_PROTO_DEFINE_ENV_VAR">BOOST_PROTO_DEFINE_ENV_VAR</a>()</code> macro. 51 </p> 52<div class="refsect2"> 53<a name="id-1.3.33.5.46.14.4.3"></a><h3> 54<a name="id-1_3_33_5_44_1_1_5_3-bb"></a><code class="computeroutput">data_type</code> public member functions</h3> 55<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"> 56<pre class="literallayout"><a name="id-1_3_33_5_44_1_1_5_3_1-bb"></a><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> Value<span class="special">></span> 57 <a class="link" href="env.html" title="Struct template env">env</a><span class="special"><</span><span class="identifier">data_type</span><span class="special">,</span> <em class="replaceable"><code><span class="identifier">see</span><span class="special">-</span><span class="identifier">below</span></code></em><span class="special">></span> <a name="id-1_3_33_5_44_1_1_5_3_1_1-bb"></a><span class="keyword">operator</span><span class="special">=</span><span class="special">(</span><span class="identifier">Value</span> <span class="special">&</span> value<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> 58<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> Value<span class="special">></span> 59 <a class="link" href="env.html" title="Struct template env">env</a><span class="special"><</span><span class="identifier">data_type</span><span class="special">,</span> <em class="replaceable"><code><span class="identifier">see</span><span class="special">-</span><span class="identifier">below</span></code></em><span class="special">></span> <a name="id-1_3_33_5_44_1_1_5_3_1_2-bb"></a><span class="keyword">operator</span><span class="special">=</span><span class="special">(</span><span class="identifier">Value</span> <span class="keyword">const</span> <span class="special">&</span> value<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre> 60<p> 61 If <code class="computeroutput">Value</code> is a specialization <code class="computeroutput">boost::reference_wrapper<T></code>, 62 this function returns <code class="computeroutput"><a class="link" href="env.html" title="Struct template env">env</a><data_type, T &>(value.get())</code>. 63 </p> 64<p> 65 Else, if the type <code class="computeroutput">Value</code> is non-copyable (i.e., a function, an array, abstract, or an ostream), 66 this function returns <code class="computeroutput"><a class="link" href="env.html" title="Struct template env">env</a><data_type, Value <em class="replaceable"><code>cv</code></em> &>(value)</code>, 67 where <code class="computeroutput"><em class="replaceable"><code>cv</code></em></code> is <code class="computeroutput">const</code> for the second overload, and empty 68 for the first. 69 </p> 70<p> 71 Otherwise, this function returns <code class="computeroutput"><a class="link" href="env.html" title="Struct template env">env</a><data_type, Value>(value)</code>. 72 </p> 73</li></ol></div> 74</div> 75</div> 76</div> 77<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 78<td align="left"></td> 79<td align="right"><div class="copyright-footer">Copyright © 2008 Eric Niebler<p> 80 Distributed under the Boost Software License, Version 1.0. (See accompanying 81 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>) 82 </p> 83</div></td> 84</tr></table> 85<hr> 86<div class="spirit-nav"> 87<a accesskey="p" href="is_env.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../proto/reference.html#header.boost.proto.transform.env_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="data.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 88</div> 89</body> 90</html> 91
