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<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><a href="operator=.html" title="cpp/experimental/shared future/operator="><span class="t-lines"><span>shared_future::operator=</span></span></a></div></div></td></tr>
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<tr class="t-nv"><td colspan="5"><div class="t-nv-ln-table"><div><strong class="selflink"><span class="t-lines"><span>shared_future::then</span></span></strong></div></div></td></tr>
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<table class="t-dcl-begin"><tbody>
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<td class="t-dcl-nopad"> <div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span> <span class="sy1"><</span> <span class="kw1">class</span> F <span class="sy1">></span><br />
future<span class="sy1"><</span><span class="coMULTI">/* see below */</span><span class="sy1">></span> then<span class="br0">(</span>F<span class="sy3">&&</span> func<span class="br0">)</span> <span class="kw4">const</span><span class="sy4">;</span></span></div></td>
<td class="t-dcl-nopad"> </td>
<td class="t-dcl-nopad"> </td>
</tr>
<tr class="t-dcl-sep"><td></td><td></td><td></td></tr>
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<p>Attach the continuation <code>func</code> to <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span>. The behavior is undefined if <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> has no associated shared state (i.e., <span class="t-c"><span class="mw-geshi cpp source-cpp">valid<span class="br0">(</span><span class="br0">)</span> <span class="sy1">==</span> <span class="kw2">false</span></span></span>).
</p><p>Creates a shared state associated with the <code>future</code> object to be returned, and a copy <span class="t-c"><span class="mw-geshi cpp source-cpp">fd</span></span> of <code>func</code> constructed as if by <span class="t-c"><span class="mw-geshi cpp source-cpp">DECAY_COPY<span class="br0">(</span><a href="../../utility/forward.html"><span class="kw1114">std::<span class="me2">forward</span></span></a><span class="sy1"><</span>F<span class="sy1">></span><span class="br0">(</span>func<span class="br0">)</span><span class="br0">)</span></span></span> evaluated in the thread calling <code>then</code>, where <span class="t-c"><span class="mw-geshi cpp source-cpp">DECAY_COPY</span></span> is defined as
</p>
<table class="eq-fun-cpp-table">
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<td>
<div dir="ltr" class="mw-geshi" style="text-align: left;"><div class="cpp source-cpp"><pre class="de1"><span class="kw1">template</span> <span class="sy1"><</span><span class="kw1">class</span> T<span class="sy1">></span>
<a href="../../types/decay.html"><span class="kw629">std::<span class="me2">decay_t</span></span></a><span class="sy1"><</span>T<span class="sy1">></span> DECAY_COPY<span class="br0">(</span>T<span class="sy3">&&</span> v<span class="br0">)</span> <span class="br0">{</span>
<span class="kw1">return</span> <a href="../../utility/forward.html"><span class="kw1114">std::<span class="me2">forward</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="br0">(</span>v<span class="br0">)</span><span class="sy4">;</span>
<span class="br0">}</span></pre></div></div>
</td></tr></table>
<p>When the shared state currently associated with <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> is ready, the <i>continuation</i> <span class="t-c"><span class="mw-geshi cpp source-cpp">INVOKE<span class="br0">(</span>std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>fd<span class="br0">)</span>, <span class="sy2">*</span>this<span class="br0">)</span></span></span> is called on an unspecified thread of execution, where <span class="t-c"><span class="mw-geshi cpp source-cpp">INVOKE</span></span> is the operation defined in <a href="../../concept/Callable.html" title="cpp/concept/Callable"><code>Callable</code></a>. If that expression is invalid, the behavior is undefined.
</p><p>Any value returned from the continuation is stored as the result in the shared state of the returned <code>future</code> object. Any exception propagated from the execution of the continuation is stored as the exceptional result in the shared state of the returned <code>future</code> object.
</p><p>Let <code>U</code> be the return type of the continuation (i.e. <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="../../types/result_of.html"><span class="kw640">std::<span class="me2">result_of_t</span></span></a><span class="sy1"><</span><a href="../../types/decay.html"><span class="kw629">std::<span class="me2">decay_t</span></span></a><span class="sy1"><</span>F<span class="sy1">></span><span class="br0">(</span><span class="kw4">const</span> std<span class="sy4">::</span><span class="me2">experimental</span><span class="sy4">::</span><span class="me2">shared_future</span><span class="sy1"><</span>T<span class="sy1">></span> <span class="sy3">&</span><span class="br0">)</span><span class="sy1">></span></span></span>). If <code>U</code> is <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">experimental</span><span class="sy4">::</span><span class="me2">future</span><span class="sy1"><</span>T2<span class="sy1">></span></span></span> for some type <code>T2</code>, then the return type of <code>then</code> is <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">experimental</span><span class="sy4">::</span><span class="me2">future</span><span class="sy1"><</span>T2<span class="sy1">></span></span></span>, otherwise it is <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">experimental</span><span class="sy4">::</span><span class="me2">future</span><span class="sy1"><</span>U<span class="sy1">></span></span></span>. This is known as <i>implicit unwrapping</i>.
</p><p>If implicit unwrapping takes place and the continuation returns an invalid <code>future</code>, then the shared state is made ready with an exception of type <span class="t-lc"><a href="../../thread/future_error.html" title="cpp/thread/future error">std::future_error</a></span> with an error condition of <span class="t-lc"><a href="../../thread/future_errc.html" title="cpp/thread/future errc">std::future_errc::broken_promise</a></span>.
</p><p>After this function returns, <span class="t-c"><span class="mw-geshi cpp source-cpp">valid<span class="br0">(</span><span class="br0">)</span></span></span> is <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span>.
</p>
<h3><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/experimental/future/then&action=edit&section=T-1" title="Template:cpp/experimental/future/then">edit</a>]</span> <span class="mw-headline" id="Parameters">Parameters</span></h3>
<table class="t-par-begin">
<tr class="t-par">
<td> func
</td>
<td> -
</td>
<td> A continuation to be attached.
</td></tr></table>
<h3><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/experimental/future/then&action=edit&section=T-2" title="Template:cpp/experimental/future/then">edit</a>]</span> <span class="mw-headline" id="Return_value"> Return value </span></h3>
<p>A <span class="t-lc">std::experimental::future</span> object associated with the shared state created by this object. <span class="t-c"><span class="mw-geshi cpp source-cpp">valid<span class="br0">(</span><span class="br0">)</span> <span class="sy1">==</span> <span class="kw2">true</span></span></span> for the returned object.
</p>
<h3><span class="editsection">[<a href="http://en.cppreference.com/mwiki/index.php?title=Template:cpp/experimental/future/then&action=edit&section=T-3" title="Template:cpp/experimental/future/then">edit</a>]</span> <span class="mw-headline" id="Example">Example</span></h3>
<table class="metadata plainlinks ambox mbox-small-left ambox-notice" style=""><tr><td class="mbox-empty-cell"></td><td class="mbox-text" style="">This section is incomplete<br />Reason: no example </td></tr></table>
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