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<div class="titlepage"><div><div><h3 class="title">
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<a name="boost_asio.reference.use_future_t"></a><a class="link" href="use_future_t.html" title="use_future_t">use_future_t</a>
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</h3></div></div></div>
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<p>
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<a class="indexterm" name="boost_asio.indexterm.use_future_t"></a>
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</p>
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<p>
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Class used to specify that an asynchronous operation should return a future.
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</p>
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<pre class="programlisting">template<
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typename Allocator = std::allocator<void>>
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class use_future_t
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</pre>
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<h5>
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<a name="boost_asio.reference.use_future_t.h0"></a>
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<span class="phrase"><a name="boost_asio.reference.use_future_t.types"></a></span><a class="link" href="use_future_t.html#boost_asio.reference.use_future_t.types">Types</a>
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</h5>
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<div class="informaltable"><table class="table">
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Name
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Description
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</tr></thead>
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<p>
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<a class="link" href="use_future_t/allocator_type.html" title="use_future_t::allocator_type"><span class="bold"><strong>allocator_type</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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The allocator type. The allocator is used when constructing the
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std::promise object for a given asynchronous operation.
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</p>
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</td>
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</tr></tbody>
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</table></div>
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<h5>
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<a name="boost_asio.reference.use_future_t.h1"></a>
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<span class="phrase"><a name="boost_asio.reference.use_future_t.member_functions"></a></span><a class="link" href="use_future_t.html#boost_asio.reference.use_future_t.member_functions">Member
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Functions</a>
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</h5>
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<div class="informaltable"><table class="table">
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<colgroup>
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Name
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Description
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<tbody>
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<p>
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<a class="link" href="use_future_t/get_allocator.html" title="use_future_t::get_allocator"><span class="bold"><strong>get_allocator</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Obtain allocator.
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</p>
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</td>
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<p>
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<a class="link" href="use_future_t/operator_lp__rp_.html" title="use_future_t::operator()"><span class="bold"><strong>operator()</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Wrap a function object in a packaged task.
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</p>
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</td>
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</tr>
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<tr>
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<p>
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<a class="link" href="use_future_t/operator_lb__rb_.html" title="use_future_t::operator[]"><span class="bold"><strong>operator[]</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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(Deprecated: Use rebind().) Specify an alternate allocator.
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</p>
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</td>
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</tr>
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<tr>
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<p>
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<a class="link" href="use_future_t/rebind.html" title="use_future_t::rebind"><span class="bold"><strong>rebind</strong></span></a>
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</p>
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</td>
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<td>
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<p>
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Specify an alternate allocator.
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</p>
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</td>
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</tr>
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<tr>
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<td>
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<p>
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<a class="link" href="use_future_t/use_future_t.html" title="use_future_t::use_future_t"><span class="bold"><strong>use_future_t</strong></span></a> <span class="silver">[constructor]</span>
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</p>
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</td>
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<td>
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<p>
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Construct using default-constructed allocator. <br> <span class="silver"> —</span><br> Construct
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using specified allocator.
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</p>
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</td>
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</tr>
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</tbody>
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</table></div>
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<p>
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The <a class="link" href="use_future_t.html" title="use_future_t"><code class="computeroutput">use_future_t</code></a>
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class is used to indicate that an asynchronous operation should return a
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std::future object. A <a class="link" href="use_future_t.html" title="use_future_t"><code class="computeroutput">use_future_t</code></a>
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object may be passed as a handler to an asynchronous operation, typically
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using the special value <code class="computeroutput">boost::asio::use_future</code>. For example:
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</p>
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<pre class="programlisting">std::future<std::size_t> my_future
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= my_socket.async_read_some(my_buffer, boost::asio::use_future);
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</pre>
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<p>
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The initiating function (async_read_some in the above example) returns a
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future that will receive the result of the operation. If the operation completes
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with an error_code indicating failure, it is converted into a system_error
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and passed back to the caller via the future.
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</p>
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<h5>
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<a name="boost_asio.reference.use_future_t.h2"></a>
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<span class="phrase"><a name="boost_asio.reference.use_future_t.requirements"></a></span><a class="link" href="use_future_t.html#boost_asio.reference.use_future_t.requirements">Requirements</a>
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</h5>
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<p>
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<span class="emphasis"><em>Header: </em></span><code class="literal">boost/asio/use_future.hpp</code>
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</p>
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<p>
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<span class="emphasis"><em>Convenience header: </em></span><code class="literal">boost/asio.hpp</code>
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</p>
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</div>
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<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
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<td align="left"></td>
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<td align="right"><div class="copyright-footer">Copyright © 2003-2021 Christopher
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M. Kohlhoff<p>
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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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>)
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