1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Movable I/O Objects</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="../cpp2011.html" title="C++ 2011 Support"> 9<link rel="prev" href="../cpp2011.html" title="C++ 2011 Support"> 10<link rel="next" href="move_handlers.html" title="Movable Handlers"> 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="../cpp2011.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../cpp2011.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="move_handlers.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.overview.cpp2011.move_objects"></a><a class="link" href="move_objects.html" title="Movable I/O Objects">Movable I/O 28 Objects</a> 29</h4></div></div></div> 30<p> 31 When move support is available (via rvalue references), Boost.Asio allows 32 move construction and assignment of sockets, serial ports, POSIX descriptors 33 and Windows handles. 34 </p> 35<p> 36 Move support allows you to write code like: 37 </p> 38<pre class="programlisting">tcp::socket make_socket(io_context& i) 39{ 40 tcp::socket s(i); 41 ... 42 std::move(s); 43} 44</pre> 45<p> 46 or: 47 </p> 48<pre class="programlisting">class connection : public enable_shared_from_this<connection> 49{ 50private: 51 tcp::socket socket_; 52 ... 53public: 54 connection(tcp::socket&& s) : socket_(std::move(s)) {} 55 ... 56}; 57 58... 59 60class server 61{ 62private: 63 tcp::acceptor acceptor_; 64 ... 65 void handle_accept(error_code ec, tcp::socket socket) 66 { 67 if (!ec) 68 std::make_shared<connection>(std::move(socket))->go(); 69 acceptor_.async_accept(...); 70 } 71 ... 72}; 73</pre> 74<p> 75 as well as: 76 </p> 77<pre class="programlisting">std::vector<tcp::socket> sockets; 78sockets.push_back(tcp::socket(...)); 79</pre> 80<p> 81 A word of warning: There is nothing stopping you from moving these objects 82 while there are pending asynchronous operations, but it is unlikely to 83 be a good idea to do so. In particular, composed operations like <a class="link" href="../../reference/async_read.html" title="async_read">async_read()</a> store a reference 84 to the stream object. Moving during the composed operation means that the 85 composed operation may attempt to access a moved-from object. 86 </p> 87<p> 88 Move support is automatically enabled for <code class="literal">g++</code> 4.5 and 89 later, when the <code class="literal">-std=c++0x</code> or <code class="literal">-std=gnu++0x</code> 90 compiler options are used. It may be disabled by defining <code class="computeroutput">BOOST_ASIO_DISABLE_MOVE</code>, 91 or explicitly enabled for other compilers by defining <code class="computeroutput">BOOST_ASIO_HAS_MOVE</code>. 92 Note that these macros also affect the availability of <a class="link" href="move_handlers.html" title="Movable Handlers">movable 93 handlers</a>. 94 </p> 95</div> 96<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 97<td align="left"></td> 98<td align="right"><div class="copyright-footer">Copyright © 2003-2020 Christopher M. 99 Kohlhoff<p> 100 Distributed under the Boost Software License, Version 1.0. (See accompanying 101 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>) 102 </p> 103</div></td> 104</tr></table> 105<hr> 106<div class="spirit-nav"> 107<a accesskey="p" href="../cpp2011.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../cpp2011.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="move_handlers.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> 108</div> 109</body> 110</html> 111
