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<div class="titlepage"><div><div><h3 class="title">
<a name="asio.reference.Sender"></a><a class="link" href="Sender.html" title="Sender concepts">Sender concepts</a>
</h3></div></div></div>
<h5>
<a name="asio.reference.Sender.h0"></a>
<span><a name="asio.reference.Sender.sender_and_sender_to"></a></span><a class="link" href="Sender.html#asio.reference.Sender.sender_and_sender_to">sender
and sender_to</a>
</h5>
<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">S</span><span class="special">></span>
<span class="identifier">concept</span> <span class="identifier">sender</span> <span class="special">=</span>
<span class="identifier">move_constructible</span><span class="special"><</span><span class="identifier">remove_cvref_t</span><span class="special"><</span><span class="identifier">S</span><span class="special">>></span> <span class="special">&&</span>
<span class="special">!</span><span class="identifier">requires</span> <span class="special">{</span>
<span class="keyword">typename</span> <span class="identifier">sender_traits</span><span class="special"><</span><span class="identifier">remove_cvref_t</span><span class="special"><</span><span class="identifier">S</span><span class="special">>>::</span><span class="identifier">__unspecialized</span><span class="special">;</span> <span class="comment">// exposition only</span>
<span class="special">};</span>
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">S</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">R</span><span class="special">></span>
<span class="identifier">concept</span> <span class="identifier">sender_to</span> <span class="special">=</span>
<span class="identifier">sender</span><span class="special"><</span><span class="identifier">S</span><span class="special">></span> <span class="special">&&</span>
<span class="identifier">receiver</span><span class="special"><</span><span class="identifier">R</span><span class="special">></span> <span class="special">&&</span>
<span class="identifier">requires</span> <span class="special">(</span><span class="identifier">S</span><span class="special">&&</span> <span class="identifier">s</span><span class="special">,</span> <span class="identifier">R</span><span class="special">&&</span> <span class="identifier">r</span><span class="special">)</span> <span class="special">{</span>
<span class="identifier">execution</span><span class="special">::</span><span class="identifier">connect</span><span class="special">((</span><span class="identifier">S</span><span class="special">&&)</span> <span class="identifier">s</span><span class="special">,</span> <span class="special">(</span><span class="identifier">R</span><span class="special">&&)</span> <span class="identifier">r</span><span class="special">);</span>
<span class="special">};</span>
</pre>
<p>
None of these operations shall introduce data races as a result of concurrent
invocations of those functions from different threads.
</p>
<p>
A sender type's destructor shall not block pending completion of the submitted
function objects.
</p>
<p>
[<span class="emphasis"><em>Note:</em></span> The ability to wait for completion of submitted
function objects may be provided by the associated execution context. —<span class="emphasis"><em>end
note</em></span>]
</p>
<h5>
<a name="asio.reference.Sender.h1"></a>
<span><a name="asio.reference.Sender.typed_sender"></a></span><a class="link" href="Sender.html#asio.reference.Sender.typed_sender">typed_sender</a>
</h5>
<p>
A sender is <span class="bold"><strong>typed</strong></span> if it declares what types
it sends through a receiver's channels. The <code class="computeroutput"><span class="identifier">typed_sender</span></code>
concept is defined as:
</p>
<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">template</span><span class="special"><</span><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span><span class="special">...></span> <span class="keyword">class</span> <span class="identifier">Tuple</span><span class="special">,</span> <span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span><span class="special">...></span> <span class="keyword">class</span> <span class="identifier">Variant</span><span class="special">></span> <span class="keyword">class</span><span class="special">></span>
<span class="keyword">struct</span> <span class="identifier">has</span><span class="special">-</span><span class="identifier">value</span><span class="special">-</span><span class="identifier">types</span><span class="special">;</span> <span class="comment">// exposition only</span>
<span class="keyword">template</span><span class="special"><</span><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span><span class="special">...></span> <span class="keyword">class</span> <span class="identifier">Variant</span><span class="special">></span>
<span class="keyword">struct</span> <span class="identifier">has</span><span class="special">-</span><span class="identifier">error</span><span class="special">-</span><span class="identifier">types</span><span class="special">;</span> <span class="comment">// exposition only</span>
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">S</span><span class="special">></span>
<span class="identifier">concept</span> <span class="identifier">has</span><span class="special">-</span><span class="identifier">sender</span><span class="special">-</span><span class="identifier">types</span> <span class="special">=</span> <span class="comment">// exposition only</span>
<span class="identifier">requires</span> <span class="special">{</span>
<span class="keyword">typename</span> <span class="identifier">has</span><span class="special">-</span><span class="identifier">value</span><span class="special">-</span><span class="identifier">types</span><span class="special"><</span><span class="identifier">S</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">value_types</span><span class="special">>;</span>
<span class="keyword">typename</span> <span class="identifier">has</span><span class="special">-</span><span class="identifier">error</span><span class="special">-</span><span class="identifier">types</span><span class="special"><</span><span class="identifier">S</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">error_types</span><span class="special">>;</span>
<span class="keyword">typename</span> <span class="identifier">bool_constant</span><span class="special"><</span><span class="identifier">S</span><span class="special">::</span><span class="identifier">sends_done</span><span class="special">>;</span>
<span class="special">};</span>
<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">S</span><span class="special">></span>
<span class="identifier">concept</span> <span class="identifier">typed_sender</span> <span class="special">=</span>
<span class="identifier">sender</span><span class="special"><</span><span class="identifier">S</span><span class="special">></span> <span class="special">&&</span>
<span class="identifier">has</span><span class="special">-</span><span class="identifier">sender</span><span class="special">-</span><span class="identifier">types</span><span class="special"><</span><span class="identifier">sender_traits</span><span class="special"><</span><span class="identifier">remove_cvref_t</span><span class="special"><</span><span class="identifier">S</span><span class="special">>>>;</span>
</pre>
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<div class="copyright-footer">Copyright © 2003-2023 Christopher M. Kohlhoff<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
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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