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<div class="titlepage"><div><div><h3 class="title">
<a name="asio.reference.WriteHandler"></a><a class="link" href="WriteHandler.html" title="Write handler requirements">Write handler requirements</a>
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<p>
A write 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 write 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">s</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">s</span></code> is an lvalue of type
<code class="computeroutput"><span class="keyword">const</span> <span class="identifier">size_t</span></code>.
</p>
<a name="asio.reference.WriteHandler.examples"></a><h5>
<a name="id721383"></a>
<a class="link" href="WriteHandler.html#asio.reference.WriteHandler.examples">Examples</a>
</h5>
<p>
A free function as a write handler:
</p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">write_handler</span><span class="special">(</span>
<span class="keyword">const</span> <span class="identifier">asio</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">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">bytes_transferred</span><span class="special">)</span>
<span class="special">{</span>
<span class="special">...</span>
<span class="special">}</span>
</pre>
<p>
A write handler function object:
</p>
<pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">write_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">asio</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">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">bytes_transferred</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 write 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">write_handler</span><span class="special">(</span>
<span class="keyword">const</span> <span class="identifier">asio</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">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">bytes_transferred</span><span class="special">)</span>
<span class="special">{</span>
<span class="special">...</span>
<span class="special">}</span>
<span class="special">...</span>
<span class="identifier">socket</span><span class="special">.</span><span class="identifier">async_write</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">write_handler</span><span class="special">,</span>
<span class="keyword">this</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">asio</span><span class="special">::</span><span class="identifier">placeholders</span><span class="special">::</span><span class="identifier">bytes_transferred</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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