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| <div class="titlepage"><div><div><h3 class="title"> |
| <a name="boost_asio.reference.ResolveHandler"></a><a class="link" href="ResolveHandler.html" title="Resolve handler requirements">Resolve handler |
| requirements</a> |
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| <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"><span class="identifier">h</span></code> of a resolve handler |
| class should work correctly in the expression <code class="computeroutput"><span class="identifier">h</span><span class="special">(</span><span class="identifier">ec</span><span class="special">,</span> |
| <span class="identifier">i</span><span class="special">)</span></code>, |
| where <code class="computeroutput"><span class="identifier">ec</span></code> is an lvalue of |
| type <code class="computeroutput"><span class="keyword">const</span> <span class="identifier">error_code</span></code> |
| and <code class="computeroutput"><span class="identifier">i</span></code> is an lvalue of type |
| <code class="computeroutput"><span class="keyword">const</span> <span class="identifier">ip</span><span class="special">::</span><span class="identifier">basic_resolver_iterator</span><span class="special"><</span><span class="identifier">InternetProtocol</span><span class="special">></span></code>. <code class="computeroutput"><span class="identifier">InternetProtocol</span></code> |
| is the template parameter of the <a class="link" href="ip__resolver_service.html" title="ip::resolver_service"><code class="computeroutput"><span class="identifier">resolver_service</span></code></a> which is used to |
| initiate the asynchronous operation. |
| </p> |
| <a name="boost_asio.reference.ResolveHandler.examples"></a><h5> |
| <a name="id844547"></a> |
| <a class="link" href="ResolveHandler.html#boost_asio.reference.ResolveHandler.examples">Examples</a> |
| </h5> |
| <p> |
| A free function as a resolve handler: |
| </p> |
| <pre class="programlisting"><span class="keyword">void</span> <span class="identifier">resolve_handler</span><span class="special">(</span> |
| <span class="keyword">const</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&</span> <span class="identifier">ec</span><span class="special">,</span> |
| <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">resolver</span><span class="special">::</span><span class="identifier">iterator</span> <span class="identifier">iterator</span><span class="special">)</span> |
| <span class="special">{</span> |
| <span class="special">...</span> |
| <span class="special">}</span> |
| </pre> |
| <p> |
| A resolve handler function object: |
| </p> |
| <pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">resolve_handler</span> |
| <span class="special">{</span> |
| <span class="special">...</span> |
| <span class="keyword">void</span> <span class="keyword">operator</span><span class="special">()(</span> |
| <span class="keyword">const</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&</span> <span class="identifier">ec</span><span class="special">,</span> |
| <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">resolver</span><span class="special">::</span><span class="identifier">iterator</span> <span class="identifier">iterator</span><span class="special">)</span> |
| <span class="special">{</span> |
| <span class="special">...</span> |
| <span class="special">}</span> |
| <span class="special">...</span> |
| <span class="special">};</span> |
| </pre> |
| <p> |
| A non-static class member function adapted to a resolve handler using <code class="computeroutput"><span class="identifier">bind</span><span class="special">()</span></code>: |
| </p> |
| <pre class="programlisting"><span class="keyword">void</span> <span class="identifier">my_class</span><span class="special">::</span><span class="identifier">resolve_handler</span><span class="special">(</span> |
| <span class="keyword">const</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&</span> <span class="identifier">ec</span><span class="special">,</span> |
| <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">ip</span><span class="special">::</span><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">resolver</span><span class="special">::</span><span class="identifier">iterator</span> <span class="identifier">iterator</span><span class="special">)</span> |
| <span class="special">{</span> |
| <span class="special">...</span> |
| <span class="special">}</span> |
| <span class="special">...</span> |
| <span class="identifier">resolver</span><span class="special">.</span><span class="identifier">async_resolve</span><span class="special">(...,</span> |
| <span class="identifier">boost</span><span class="special">::</span><span class="identifier">bind</span><span class="special">(&</span><span class="identifier">my_class</span><span class="special">::</span><span class="identifier">resolve_handler</span><span class="special">,</span> |
| <span class="keyword">this</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">placeholders</span><span class="special">::</span><span class="identifier">error</span><span class="special">,</span> |
| <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">placeholders</span><span class="special">::</span><span class="identifier">iterator</span><span class="special">));</span> |
| </pre> |
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| <td align="right"><div class="copyright-footer">Copyright © 2003 - 2010 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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