1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Class template field</title> 5<link rel="stylesheet" href="../../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../index.html" title="Chapter 1. Boost.Compute"> 8<link rel="up" href="../../boost_compute/reference.html#header.boost.compute.functional.field_hpp" title="Header <boost/compute/functional/field.hpp>"> 9<link rel="prev" href="convert.html" title="Struct template convert"> 10<link rel="next" href="get.html" title="Struct template get"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="convert.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../boost_compute/reference.html#header.boost.compute.functional.field_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="get.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="refentry"> 26<a name="boost.compute.field"></a><div class="titlepage"></div> 27<div class="refnamediv"> 28<h2><span class="refentrytitle">Class template field</span></h2> 29<p>boost::compute::field</p> 30</div> 31<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> 32<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="../../boost_compute/reference.html#header.boost.compute.functional.field_hpp" title="Header <boost/compute/functional/field.hpp>">boost/compute/functional/field.hpp</a>> 33 34</span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> T<span class="special">></span> 35<span class="keyword">class</span> <a class="link" href="field.html" title="Class template field">field</a> <span class="special">{</span> 36<span class="keyword">public</span><span class="special">:</span> 37 <span class="comment">// types</span> 38 <span class="keyword">typedef</span> <span class="identifier">T</span> <a name="boost.compute.field.result_type"></a><span class="identifier">result_type</span><span class="special">;</span> <span class="comment">// Result type. </span> 39 40 <span class="comment">// <a class="link" href="field.html#boost.compute.fieldconstruct-copy-destruct">construct/copy/destruct</a></span> 41 <a class="link" href="field.html#idm45549385410944-bb"><span class="identifier">field</span></a><span class="special">(</span><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="special">&</span><span class="special">)</span><span class="special">;</span> 42<span class="special">}</span><span class="special">;</span></pre></div> 43<div class="refsect1"> 44<a name="idm45849510769520"></a><h2>Description</h2> 45<p>Returns the named field from a value.</p> 46<p>The template-type <code class="computeroutput">T</code> specifies the field's value type. Note that the value type must match the actual type of the field otherwise runtime compilation or logic errors may occur.</p> 47<p>For example, to access the <code class="computeroutput">second</code> field in a <code class="computeroutput">std::pair<int, float></code> object: </p> 48<pre class="programlisting"><span class="identifier">field</span><span class="special"><</span><span class="keyword">float</span><span class="special">></span><span class="special">(</span><span class="string">"second"</span><span class="special">)</span><span class="special">;</span> 49</pre> 50<p>This can also be used with vector types to access individual components as well as perform swizzle operations.</p> 51<p>For example, to access the first and third components of an <code class="computeroutput">int</code> vector type (e.g. <code class="computeroutput">int4</code>): </p> 52<pre class="programlisting"><span class="identifier">field</span><span class="special"><</span><span class="identifier">int2_</span><span class="special">></span><span class="special">(</span><span class="string">"xz"</span><span class="special">)</span><span class="special">;</span> 53</pre> 54<p><span class="bold"><strong>See Also:</strong></span></p> 55<p><a class="link" href="get.html" title="Struct template get">get<N></a> </p> 56<p> 57</p> 58<p> 59</p> 60<div class="refsect2"> 61<a name="idm45849510751792"></a><h3> 62<a name="boost.compute.fieldconstruct-copy-destruct"></a><code class="computeroutput">field</code> 63 public 64 construct/copy/destruct</h3> 65<div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"> 66<pre class="literallayout"><a name="idm45549385410944-bb"></a><span class="identifier">field</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="special">&</span> field<span class="special">)</span><span class="special">;</span></pre>Creates a new field functor with <code class="computeroutput">field</code>. </li></ol></div> 67</div> 68</div> 69</div> 70<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 71<td align="left"></td> 72<td align="right"><div class="copyright-footer">Copyright © 2013, 2014 Kyle Lutz<p> 73 Distributed under the Boost Software License, Version 1.0. (See accompanying 74 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>) 75 </p> 76</div></td> 77</tr></table> 78<hr> 79<div class="spirit-nav"> 80<a accesskey="p" href="convert.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../boost_compute/reference.html#header.boost.compute.functional.field_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="get.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 81</div> 82</body> 83</html> 84
