1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>http::is_body_writer</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.Beast"> 8<link rel="up" href="../ref.html" title="This Page Intentionally Left Blank 2/2"> 9<link rel="prev" href="boost__beast__http__is_body.html" title="http::is_body"> 10<link rel="next" href="boost__beast__http__is_mutable_body_writer.html" title="http::is_mutable_body_writer"> 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="boost__beast__http__is_body.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../ref.html"><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="boost__beast__http__is_mutable_body_writer.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h4 class="title"> 27<a name="beast.ref.boost__beast__http__is_body_writer"></a><a class="link" href="boost__beast__http__is_body_writer.html" title="http::is_body_writer">http::is_body_writer</a> 28</h4></div></div></div> 29<p> 30 <a class="indexterm" name="idm46057507565104"></a> 31 </p> 32<p> 33 Determine if a type has a nested <span class="emphasis"><em>BodyWriter</em></span>. 34 </p> 35<h5> 36<a name="beast.ref.boost__beast__http__is_body_writer.h0"></a> 37 <span class="phrase"><a name="beast.ref.boost__beast__http__is_body_writer.synopsis"></a></span><a class="link" href="boost__beast__http__is_body_writer.html#beast.ref.boost__beast__http__is_body_writer.synopsis">Synopsis</a> 38 </h5> 39<p> 40 Defined in header <code class="literal"><<a href="../../../../../../boost/beast/http/type_traits.hpp" target="_top">boost/beast/http/type_traits.hpp</a>></code> 41 </p> 42<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> 43 <span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> 44<span class="keyword">using</span> <span class="identifier">is_body_writer</span> <span class="special">=</span> <span class="emphasis"><em>see-below</em></span><span class="special">;</span> 45</pre> 46<h5> 47<a name="beast.ref.boost__beast__http__is_body_writer.h1"></a> 48 <span class="phrase"><a name="beast.ref.boost__beast__http__is_body_writer.description"></a></span><a class="link" href="boost__beast__http__is_body_writer.html#beast.ref.boost__beast__http__is_body_writer.description">Description</a> 49 </h5> 50<p> 51 This alias template is <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">true_type</span></code> 52 when: 53 </p> 54<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 55<li class="listitem"> 56 <code class="computeroutput"><span class="identifier">T</span></code> has a nested type named 57 <code class="computeroutput"><span class="identifier">writer</span></code> 58 </li> 59<li class="listitem"> 60 <code class="computeroutput"><span class="identifier">writer</span></code> meets the requirements 61 of <span class="emphasis"><em>BodyWriter</em></span>. 62 </li> 63</ul></div> 64<h5> 65<a name="beast.ref.boost__beast__http__is_body_writer.h2"></a> 66 <span class="phrase"><a name="beast.ref.boost__beast__http__is_body_writer.template_parameters"></a></span><a class="link" href="boost__beast__http__is_body_writer.html#beast.ref.boost__beast__http__is_body_writer.template_parameters">Template 67 Parameters</a> 68 </h5> 69<div class="informaltable"><table class="table"> 70<colgroup> 71<col> 72<col> 73</colgroup> 74<thead><tr> 75<th> 76 <p> 77 Type 78 </p> 79 </th> 80<th> 81 <p> 82 Description 83 </p> 84 </th> 85</tr></thead> 86<tbody><tr> 87<td> 88 <p> 89 <code class="computeroutput"><span class="identifier">T</span></code> 90 </p> 91 </td> 92<td> 93 <p> 94 The body type to test. 95 </p> 96 </td> 97</tr></tbody> 98</table></div> 99<h5> 100<a name="beast.ref.boost__beast__http__is_body_writer.h3"></a> 101 <span class="phrase"><a name="beast.ref.boost__beast__http__is_body_writer.example"></a></span><a class="link" href="boost__beast__http__is_body_writer.html#beast.ref.boost__beast__http__is_body_writer.example">Example</a> 102 </h5> 103<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">bool</span> <span class="identifier">isRequest</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Body</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Fields</span><span class="special">></span> 104<span class="keyword">void</span> <span class="identifier">check_can_serialize</span><span class="special">(</span><span class="identifier">message</span><span class="special"><</span><span class="identifier">isRequest</span><span class="special">,</span> <span class="identifier">Body</span><span class="special">,</span> <span class="identifier">Fields</span><span class="special">></span> <span class="keyword">const</span><span class="special">&)</span> 105<span class="special">{</span> 106 <span class="keyword">static_assert</span><span class="special">(</span><span class="identifier">is_body_writer</span><span class="special"><</span><span class="identifier">Body</span><span class="special">>::</span><span class="identifier">value</span><span class="special">,</span> 107 <span class="string">"Cannot serialize Body, no reader"</span><span class="special">);</span> 108<span class="special">}</span> 109</pre> 110</div> 111<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 112<td align="left"></td> 113<td align="right"><div class="copyright-footer">Copyright © 2016-2019 Vinnie 114 Falco<p> 115 Distributed under the Boost Software License, Version 1.0. (See accompanying 116 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>) 117 </p> 118</div></td> 119</tr></table> 120<hr> 121<div class="spirit-nav"> 122<a accesskey="p" href="boost__beast__http__is_body.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../ref.html"><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="boost__beast__http__is_mutable_body_writer.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 123</div> 124</body> 125</html> 126
