1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Sender concepts</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="../reference.html" title="Reference"> 9<link rel="prev" href="Scheduler.html" title="Scheduler concept"> 10<link rel="next" href="Service.html" title="Service requirements"> 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="Scheduler.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../reference.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="Service.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h3 class="title"> 27<a name="boost_asio.reference.Sender"></a><a class="link" href="Sender.html" title="Sender concepts">Sender concepts</a> 28</h3></div></div></div> 29<h5> 30<a name="boost_asio.reference.Sender.h0"></a> 31 <span class="phrase"><a name="boost_asio.reference.Sender.sender_and_sender_to"></a></span><a class="link" href="Sender.html#boost_asio.reference.Sender.sender_and_sender_to">sender 32 and sender_to</a> 33 </h5> 34<pre class="programlisting">template<class S> 35 concept sender = 36 move_constructible<remove_cvref_t<S>> && 37 !requires { 38 typename sender_traits<remove_cvref_t<S>>::__unspecialized; // exposition only 39 }; 40 41template<class S, class R> 42 concept sender_to = 43 sender<S> && 44 receiver<R> && 45 requires (S&& s, R&& r) { 46 execution::connect((S&&) s, (R&&) r); 47 }; 48</pre> 49<p> 50 None of these operations shall introduce data races as a result of concurrent 51 invocations of those functions from different threads. 52 </p> 53<p> 54 A sender type's destructor shall not block pending completion of the submitted 55 function objects. 56 </p> 57<p> 58 [<span class="emphasis"><em>Note:</em></span> The ability to wait for completion of submitted 59 function objects may be provided by the associated execution context. —<span class="emphasis"><em>end 60 note</em></span>] 61 </p> 62<h5> 63<a name="boost_asio.reference.Sender.h1"></a> 64 <span class="phrase"><a name="boost_asio.reference.Sender.typed_sender"></a></span><a class="link" href="Sender.html#boost_asio.reference.Sender.typed_sender">typed_sender</a> 65 </h5> 66<p> 67 A sender is <span class="bold"><strong>typed</strong></span> if it declares what types 68 it sends through a receiver's channels. The <code class="computeroutput">typed_sender</code> concept 69 is defined as: 70 </p> 71<pre class="programlisting">template<template<template<class...> class Tuple, template<class...> class Variant> class> 72 struct has-value-types; // exposition only 73 74template<template<class...> class Variant> 75 struct has-error-types; // exposition only 76 77template<class S> 78 concept has-sender-types = // exposition only 79 requires { 80 typename has-value-types<S::template value_types>; 81 typename has-error-types<S::template error_types>; 82 typename bool_constant<S::sends_done>; 83 }; 84 85template<class S> 86 concept typed_sender = 87 sender<S> && 88 has-sender-types<sender_traits<remove_cvref_t<S>>>; 89</pre> 90</div> 91<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 92<td align="left"></td> 93<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M. 94 Kohlhoff<p> 95 Distributed under the Boost Software License, Version 1.0. (See accompanying 96 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>) 97 </p> 98</div></td> 99</tr></table> 100<hr> 101<div class="spirit-nav"> 102<a accesskey="p" href="Scheduler.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../reference.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="Service.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 103</div> 104</body> 105</html> 106
