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<div class="titlepage"><div><div><h3 class="title">
<a name="asio.reference.spawn"></a><a class="link" href="spawn.html" title="spawn">spawn</a>
</h3></div></div></div>
<p>
        <a class="indexterm" name="asio.indexterm.spawn"></a> 
Start a new stackful coroutine.
      </p>
<p>
        Start a new stackful coroutine, calling the specified handler when it completes.
      </p>
<pre class="programlisting">template&lt;
    typename Function&gt;
void <a class="link" href="spawn/overload1.html" title="spawn (1 of 7 overloads)">spawn</a>(
    Function &amp;&amp; function,
    const boost::coroutines::attributes &amp; attributes = boost::coroutines::attributes());
  <span class="emphasis"><em>» <a class="link" href="spawn/overload1.html" title="spawn (1 of 7 overloads)">more...</a></em></span>

template&lt;
    typename <a class="link" href="Handler.html" title="Handlers">Handler</a>,
    typename Function&gt;
void <a class="link" href="spawn/overload2.html" title="spawn (2 of 7 overloads)">spawn</a>(
    Handler &amp;&amp; handler,
    Function &amp;&amp; function,
    const boost::coroutines::attributes &amp; attributes = boost::coroutines::attributes(),
    typename enable_if&lt; !is_executor&lt; typename decay&lt; Handler &gt;::type &gt;::value &amp;&amp;!execution::is_executor&lt; typename decay&lt; Handler &gt;::type &gt;::value &amp;&amp;!is_convertible&lt; Handler &amp;, execution_context &amp; &gt;::value &gt;::type *  = 0);
  <span class="emphasis"><em>» <a class="link" href="spawn/overload2.html" title="spawn (2 of 7 overloads)">more...</a></em></span>
</pre>
<p>
        Start a new stackful coroutine, inheriting the execution context of another.
      </p>
<pre class="programlisting">template&lt;
    typename <a class="link" href="Handler.html" title="Handlers">Handler</a>,
    typename Function&gt;
void <a class="link" href="spawn/overload3.html" title="spawn (3 of 7 overloads)">spawn</a>(
    basic_yield_context&lt; Handler &gt; ctx,
    Function &amp;&amp; function,
    const boost::coroutines::attributes &amp; attributes = boost::coroutines::attributes());
  <span class="emphasis"><em>» <a class="link" href="spawn/overload3.html" title="spawn (3 of 7 overloads)">more...</a></em></span>
</pre>
<p>
        Start a new stackful coroutine that executes on a given executor.
      </p>
<pre class="programlisting">template&lt;
    typename Function,
    typename <a class="link" href="Executor1.html" title="Executor requirements">Executor</a>&gt;
void <a class="link" href="spawn/overload4.html" title="spawn (4 of 7 overloads)">spawn</a>(
    const Executor &amp; ex,
    Function &amp;&amp; function,
    const boost::coroutines::attributes &amp; attributes = boost::coroutines::attributes(),
    typename enable_if&lt; is_executor&lt; Executor &gt;::value||execution::is_executor&lt; Executor &gt;::value &gt;::type *  = 0);
  <span class="emphasis"><em>» <a class="link" href="spawn/overload4.html" title="spawn (4 of 7 overloads)">more...</a></em></span>
</pre>
<p>
        Start a new stackful coroutine that executes on a given strand.
      </p>
<pre class="programlisting">template&lt;
    typename Function,
    typename <a class="link" href="Executor1.html" title="Executor requirements">Executor</a>&gt;
void <a class="link" href="spawn/overload5.html" title="spawn (5 of 7 overloads)">spawn</a>(
    const strand&lt; Executor &gt; &amp; ex,
    Function &amp;&amp; function,
    const boost::coroutines::attributes &amp; attributes = boost::coroutines::attributes());
  <span class="emphasis"><em>» <a class="link" href="spawn/overload5.html" title="spawn (5 of 7 overloads)">more...</a></em></span>
</pre>
<p>
        Start a new stackful coroutine that executes in the context of a strand.
      </p>
<pre class="programlisting">template&lt;
    typename Function&gt;
void <a class="link" href="spawn/overload6.html" title="spawn (6 of 7 overloads)">spawn</a>(
    const asio::io_context::strand &amp; s,
    Function &amp;&amp; function,
    const boost::coroutines::attributes &amp; attributes = boost::coroutines::attributes());
  <span class="emphasis"><em>» <a class="link" href="spawn/overload6.html" title="spawn (6 of 7 overloads)">more...</a></em></span>
</pre>
<p>
        Start a new stackful coroutine that executes on a given execution context.
      </p>
<pre class="programlisting">template&lt;
    typename Function,
    typename ExecutionContext&gt;
void <a class="link" href="spawn/overload7.html" title="spawn (7 of 7 overloads)">spawn</a>(
    ExecutionContext &amp; ctx,
    Function &amp;&amp; function,
    const boost::coroutines::attributes &amp; attributes = boost::coroutines::attributes(),
    typename enable_if&lt; is_convertible&lt; ExecutionContext &amp;, execution_context &amp; &gt;::value &gt;::type *  = 0);
  <span class="emphasis"><em>» <a class="link" href="spawn/overload7.html" title="spawn (7 of 7 overloads)">more...</a></em></span>
</pre>
<p>
        The <code class="computeroutput">spawn()</code> function is a high-level wrapper over the Boost.Coroutine
        library. This function enables programs to implement asynchronous logic in
        a synchronous manner, as illustrated by the following example:
      </p>
<pre class="programlisting">asio::spawn(my_strand, do_echo);

// ...

void do_echo(asio::yield_context yield)
{
  try
  {
    char data[128];
    for (;;)
    {
      std::size_t length =
        my_socket.async_read_some(
          asio::buffer(data), yield);

      asio::async_write(my_socket,
          asio::buffer(data, length), yield);
    }
  }
  catch (std::exception&amp; e)
  {
    // ...
  }
}
</pre>
<h5>
<a name="asio.reference.spawn.h0"></a>
        <span><a name="asio.reference.spawn.requirements"></a></span><a class="link" href="spawn.html#asio.reference.spawn.requirements">Requirements</a>
      </h5>
<p>
        <span class="emphasis"><em>Header: </em></span><code class="literal">asio/spawn.hpp</code>
      </p>
<p>
        <span class="emphasis"><em>Convenience header: </em></span>None
      </p>
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<td align="right"><div class="copyright-footer">Copyright © 2003-2020 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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