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<div class="titlepage"><div><div><h4 class="title">
<a name="asio.reference.system_context.has_service"></a><a class="link" href="has_service.html" title="system_context::has_service">system_context::has_service</a>
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<p>
          <span class="emphasis"><em>Inherited from execution_context.</em></span>
        </p>
<p>
          <a class="indexterm" name="asio.indexterm.system_context.has_service"></a> 
Determine
          if an <a class="link" href="../execution_context.html" title="execution_context"><code class="computeroutput">execution_context</code></a>
          contains a specified service type.
        </p>
<pre class="programlisting">template&lt;
    typename <a class="link" href="../Service.html" title="Service requirements">Service</a>&gt;
friend bool has_service(
    execution_context &amp; e);
</pre>
<p>
          This function is used to determine whether the <a class="link" href="../execution_context.html" title="execution_context"><code class="computeroutput">execution_context</code></a>
          contains a service object corresponding to the given service type.
        </p>
<h6>
<a name="asio.reference.system_context.has_service.h0"></a>
          <span><a name="asio.reference.system_context.has_service.parameters"></a></span><a class="link" href="has_service.html#asio.reference.system_context.has_service.parameters">Parameters</a>
        </h6>
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<p class="title"><b></b></p>
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<dt><span class="term">e</span></dt>
<dd><p>
                The <a class="link" href="../execution_context.html" title="execution_context"><code class="computeroutput">execution_context</code></a>
                object that owns the service.
              </p></dd>
</dl>
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<h6>
<a name="asio.reference.system_context.has_service.h1"></a>
          <span><a name="asio.reference.system_context.has_service.return_value"></a></span><a class="link" href="has_service.html#asio.reference.system_context.has_service.return_value">Return
          Value</a>
        </h6>
<p>
          A boolean indicating whether the <a class="link" href="../execution_context.html" title="execution_context"><code class="computeroutput">execution_context</code></a>
          contains the service.
        </p>
<h6>
<a name="asio.reference.system_context.has_service.h2"></a>
          <span><a name="asio.reference.system_context.has_service.requirements"></a></span><a class="link" href="has_service.html#asio.reference.system_context.has_service.requirements">Requirements</a>
        </h6>
<p>
          <span class="emphasis"><em>Header: </em></span><code class="literal">asio/system_context.hpp</code>
        </p>
<p>
          <span class="emphasis"><em>Convenience header: </em></span><code class="literal">asio.hpp</code>
        </p>
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<td align="right"><div class="copyright-footer">Copyright &#169; 2003-2019 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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