ResolveHandler.html
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<div class="titlepage"><div><div><h3 class="title">
<a name="asio.reference.ResolveHandler"></a><a class="link" href="ResolveHandler.html" title="Resolve handler requirements">Resolve handler requirements</a>
</h3></div></div></div>
<p>
A resolve handler must meet the requirements for a <a class="link" href="Handler.html" title="Handlers">handler</a>.
A value <code class="computeroutput">h</code> of a resolve handler class should work correctly in
the expression <code class="computeroutput">h(ec, r)</code>, where <code class="computeroutput">ec</code> is an lvalue
of type <code class="computeroutput">const error_code</code> and <code class="computeroutput">r</code> is an lvalue of
type <code class="computeroutput">const ip::basic_resolver_results<InternetProtocol></code>.
<code class="computeroutput">InternetProtocol</code> is the template parameter of the <a class="link" href="ip__basic_resolver.html" title="ip::basic_resolver"><code class="computeroutput">ip::basic_resolver<></code></a>
which is used to initiate the asynchronous operation.
</p>
<h5>
<a name="asio.reference.ResolveHandler.h0"></a>
<span><a name="asio.reference.ResolveHandler.examples"></a></span><a class="link" href="ResolveHandler.html#asio.reference.ResolveHandler.examples">Examples</a>
</h5>
<p>
A free function as a resolve handler:
</p>
<pre class="programlisting">void resolve_handler(
const asio::error_code& ec,
asio::ip::tcp::resolver::results_type results)
{
...
}
</pre>
<p>
A resolve handler function object:
</p>
<pre class="programlisting">struct resolve_handler
{
...
void operator()(
const asio::error_code& ec,
asio::ip::tcp::resolver::results_type results)
{
...
}
...
};
</pre>
<p>
A lambda as a resolve handler:
</p>
<pre class="programlisting">resolver.async_resolve(...,
[](const asio::error_code& ec,
asio::ip::tcp::resolver::results_type results)
{
...
});
</pre>
<p>
A non-static class member function adapted to a resolve handler using <code class="computeroutput">std::bind()</code>:
</p>
<pre class="programlisting">void my_class::resolve_handler(
const asio::error_code& ec,
asio::ip::tcp::resolver::results_type results)
{
...
}
...
resolver.async_resolve(...,
std::bind(&my_class::resolve_handler,
this, std::placeholders::_1,
std::placeholders::_2));
</pre>
<p>
A non-static class member function adapted to a resolve handler using <code class="computeroutput">boost::bind()</code>:
</p>
<pre class="programlisting">void my_class::resolve_handler(
const asio::error_code& ec,
asio::ip::tcp::resolver::results_type results)
{
...
}
...
resolver.async_resolve(...,
boost::bind(&my_class::resolve_handler,
this, asio::placeholders::error,
asio::placeholders::results));
</pre>
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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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