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<title>Movable I/O Objects</title>
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<div class="titlepage"><div><div><h4 class="title">
<a name="boost_asio.overview.cpp2011.move_objects"></a><a class="link" href="move_objects.html" title="Movable I/O Objects">Movable I/O
        Objects</a>
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<p>
          When move support is available (via rvalue references), Boost.Asio allows
          move construction and assignment of sockets, serial ports, POSIX descriptors
          and Windows handles.
        </p>
<p>
          Move support allows you to write code like:
        </p>
<pre class="programlisting">tcp::socket make_socket(io_context&amp; i)
{
  tcp::socket s(i);
  ...
  std::move(s);
}
</pre>
<p>
          or:
        </p>
<pre class="programlisting">class connection : public enable_shared_from_this&lt;connection&gt;
{
private:
  tcp::socket socket_;
  ...
public:
  connection(tcp::socket&amp;&amp; s) : socket_(std::move(s)) {}
  ...
};

...

class server
{
private:
  tcp::acceptor acceptor_;
  ...
  void handle_accept(error_code ec, tcp::socket socket)
  {
    if (!ec)
      std::make_shared&lt;connection&gt;(std::move(socket))-&gt;go();
    acceptor_.async_accept(...);
  }
  ...
};
</pre>
<p>
          as well as:
        </p>
<pre class="programlisting">std::vector&lt;tcp::socket&gt; sockets;
sockets.push_back(tcp::socket(...));
</pre>
<p>
          A word of warning: There is nothing stopping you from moving these objects
          while there are pending asynchronous operations, but it is unlikely to
          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
          to the stream object. Moving during the composed operation means that the
          composed operation may attempt to access a moved-from object.
        </p>
<p>
          Move support is automatically enabled for <code class="literal">g++</code> 4.5 and
          later, when the <code class="literal">-std=c++0x</code> or <code class="literal">-std=gnu++0x</code>
          compiler options are used. It may be disabled by defining <code class="computeroutput">BOOST_ASIO_DISABLE_MOVE</code>,
          or explicitly enabled for other compilers by defining <code class="computeroutput">BOOST_ASIO_HAS_MOVE</code>.
          Note that these macros also affect the availability of <a class="link" href="move_handlers.html" title="Movable Handlers">movable
          handlers</a>.
        </p>
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        Distributed under the Boost Software License, Version 1.0. (See accompanying
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