1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>system_context::has_service</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="../../../boost_asio.html" title="Boost.Asio"> 8<link rel="up" href="../system_context.html" title="system_context"> 9<link rel="prev" href="get_executor.html" title="system_context::get_executor"> 10<link rel="next" href="join.html" title="system_context::join"> 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="get_executor.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../system_context.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../boost_asio.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="join.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="boost_asio.reference.system_context.has_service"></a><a class="link" href="has_service.html" title="system_context::has_service">system_context::has_service</a> 28</h4></div></div></div> 29<p> 30 <span class="emphasis"><em>Inherited from execution_context.</em></span> 31 </p> 32<p> 33 <a class="indexterm" name="boost_asio.indexterm.system_context.has_service"></a> 34Determine 35 if an <a class="link" href="../execution_context.html" title="execution_context"><code class="computeroutput">execution_context</code></a> 36 contains a specified service type. 37 </p> 38<pre class="programlisting">template< 39 typename <a class="link" href="../Service.html" title="Service requirements">Service</a>> 40friend bool has_service( 41 execution_context & e); 42</pre> 43<p> 44 This function is used to determine whether the <a class="link" href="../execution_context.html" title="execution_context"><code class="computeroutput">execution_context</code></a> 45 contains a service object corresponding to the given service type. 46 </p> 47<h6> 48<a name="boost_asio.reference.system_context.has_service.h0"></a> 49 <span class="phrase"><a name="boost_asio.reference.system_context.has_service.parameters"></a></span><a class="link" href="has_service.html#boost_asio.reference.system_context.has_service.parameters">Parameters</a> 50 </h6> 51<div class="variablelist"> 52<p class="title"><b></b></p> 53<dl class="variablelist"> 54<dt><span class="term">e</span></dt> 55<dd><p> 56 The <a class="link" href="../execution_context.html" title="execution_context"><code class="computeroutput">execution_context</code></a> 57 object that owns the service. 58 </p></dd> 59</dl> 60</div> 61<h6> 62<a name="boost_asio.reference.system_context.has_service.h1"></a> 63 <span class="phrase"><a name="boost_asio.reference.system_context.has_service.return_value"></a></span><a class="link" href="has_service.html#boost_asio.reference.system_context.has_service.return_value">Return 64 Value</a> 65 </h6> 66<p> 67 A boolean indicating whether the <a class="link" href="../execution_context.html" title="execution_context"><code class="computeroutput">execution_context</code></a> 68 contains the service. 69 </p> 70<h6> 71<a name="boost_asio.reference.system_context.has_service.h2"></a> 72 <span class="phrase"><a name="boost_asio.reference.system_context.has_service.requirements"></a></span><a class="link" href="has_service.html#boost_asio.reference.system_context.has_service.requirements">Requirements</a> 73 </h6> 74<p> 75 <span class="emphasis"><em>Header: </em></span><code class="literal">boost/asio/system_context.hpp</code> 76 </p> 77<p> 78 <span class="emphasis"><em>Convenience header: </em></span><code class="literal">boost/asio.hpp</code> 79 </p> 80</div> 81<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 82<td align="left"></td> 83<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M. 84 Kohlhoff<p> 85 Distributed under the Boost Software License, Version 1.0. (See accompanying 86 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>) 87 </p> 88</div></td> 89</tr></table> 90<hr> 91<div class="spirit-nav"> 92<a accesskey="p" href="get_executor.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../system_context.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../boost_asio.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="join.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 93</div> 94</body> 95</html> 96
