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<title>Handle service requirements</title>
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<div class="titlepage"><div><div><h3 class="title">
<a name="asio.reference.HandleService"></a><a class="link" href="HandleService.html" title="Handle service requirements">Handle service requirements</a>
</h3></div></div></div>
<p>
        A handle service must meet the requirements for an <a class="link" href="IoObjectService.html" title="I/O object service requirements">I/O
        object service</a> with support for movability, as well as the additional
        requirements listed below.
      </p>
<p>
        In the table below, <code class="computeroutput"><span class="identifier">X</span></code> denotes
        a handle service class, <code class="computeroutput"><span class="identifier">a</span></code>
        and <code class="computeroutput"><span class="identifier">ao</span></code> denote values of type
        <code class="computeroutput"><span class="identifier">X</span></code>, <code class="computeroutput"><span class="identifier">b</span></code>
        and <code class="computeroutput"><span class="identifier">c</span></code> denote values of type
        <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">implementation_type</span></code>, <code class="computeroutput"><span class="identifier">n</span></code>
        denotes a value of type <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">native_handle_type</span></code>,
        <code class="computeroutput"><span class="identifier">ec</span></code> denotes a value of type
        <code class="computeroutput"><span class="identifier">error_code</span></code>, and <code class="computeroutput"><span class="identifier">u</span></code> and <code class="computeroutput"><span class="identifier">v</span></code>
        denote identifiers.
      </p>
<div class="table">
<a name="asio.reference.HandleService.t0"></a><p class="title"><b>Table&#160;14.&#160;HandleService requirements</b></p>
<div class="table-contents"><table class="table" summary="HandleService requirements">
<colgroup>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
                <p>
                  expression
                </p>
              </th>
<th>
                <p>
                  return type
                </p>
              </th>
<th>
                <p>
                  assertion/note<br> pre/post-condition
                </p>
              </th>
</tr></thead>
<tbody>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">native_handle_type</span></code>
                </p>
              </td>
<td>
              </td>
<td>
                <p>
                  The implementation-defined native representation of a handle. Must
                  satisfy the requirements of <code class="computeroutput"><span class="identifier">CopyConstructible</span></code>
                  types (C++ Std, 20.1.3), and the requirements of <code class="computeroutput"><span class="identifier">Assignable</span></code> types (C++ Std, 23.1).
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">construct</span><span class="special">(</span><span class="identifier">b</span><span class="special">);</span></code>
                </p>
              </td>
<td>
              </td>
<td>
                <p>
                  From <a class="link" href="IoObjectService.html" title="I/O object service requirements">IoObjectService</a>
                  requirements.<br> post: <code class="computeroutput"><span class="special">!</span><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">destroy</span><span class="special">(</span><span class="identifier">b</span><span class="special">);</span></code>
                </p>
              </td>
<td>
              </td>
<td>
                <p>
                  From <a class="link" href="IoObjectService.html" title="I/O object service requirements">IoObjectService</a>
                  requirements. Implicitly cancels asynchronous operations, as if
                  by calling <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">close</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span>
                  <span class="identifier">ec</span><span class="special">)</span></code>.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
</p>
<pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">move_construct</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">c</span><span class="special">);</span>
</pre>
<p>
                </p>
              </td>
<td>
              </td>
<td>
                <p>
                  From <a class="link" href="IoObjectService.html" title="I/O object service requirements">IoObjectService</a>
                  requirements. The underlying native representation is moved from
                  <code class="computeroutput"><span class="identifier">c</span></code> to <code class="computeroutput"><span class="identifier">b</span></code>.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
</p>
<pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">move_assign</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">ao</span><span class="special">,</span> <span class="identifier">c</span><span class="special">);</span>
</pre>
<p>
                </p>
              </td>
<td>
              </td>
<td>
                <p>
                  From <a class="link" href="IoObjectService.html" title="I/O object service requirements">IoObjectService</a>
                  requirements. Implicitly cancels asynchronous operations associated
                  with <code class="computeroutput"><span class="identifier">b</span></code>, as if by
                  calling <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">close</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span>
                  <span class="identifier">ec</span><span class="special">)</span></code>.
                  Then the underlying native representation is moved from <code class="computeroutput"><span class="identifier">c</span></code> to <code class="computeroutput"><span class="identifier">b</span></code>.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
</p>
<pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">assign</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">n</span><span class="special">,</span> <span class="identifier">ec</span><span class="special">);</span>
</pre>
<p>
                </p>
              </td>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">error_code</span></code>
                </p>
              </td>
<td>
                <p>
                  pre: <code class="computeroutput"><span class="special">!</span><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.<br> post: <code class="computeroutput"><span class="special">!!</span><span class="identifier">ec</span> <span class="special">||</span>
                  <span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
</p>
<pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">);</span>
</pre>
<p>
                </p>
              </td>
<td>
                <p>
                  <code class="computeroutput"><span class="keyword">bool</span></code>
                </p>
              </td>
<td>
              </td>
</tr>
<tr>
<td>
                <p>
</p>
<pre class="programlisting"><span class="keyword">const</span> <span class="identifier">X</span><span class="special">&amp;</span> <span class="identifier">u</span> <span class="special">=</span> <span class="identifier">a</span><span class="special">;</span>
<span class="keyword">const</span> <span class="identifier">X</span><span class="special">::</span><span class="identifier">implementation_type</span><span class="special">&amp;</span> <span class="identifier">v</span> <span class="special">=</span> <span class="identifier">b</span><span class="special">;</span>
<span class="identifier">u</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">v</span><span class="special">);</span>
</pre>
<p>
                </p>
              </td>
<td>
                <p>
                  <code class="computeroutput"><span class="keyword">bool</span></code>
                </p>
              </td>
<td>
              </td>
</tr>
<tr>
<td>
                <p>
</p>
<pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">close</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">ec</span><span class="special">);</span>
</pre>
<p>
                </p>
              </td>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">error_code</span></code>
                </p>
              </td>
<td>
                <p>
                  If <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">()</span></code>
                  is true, causes any outstanding asynchronous operations to complete
                  as soon as possible. Handlers for cancelled operations shall be
                  passed the error code <code class="computeroutput"><span class="identifier">error</span><span class="special">::</span><span class="identifier">operation_aborted</span></code>.<br>
                  post: <code class="computeroutput"><span class="special">!</span><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.
                </p>
              </td>
</tr>
<tr>
<td>
                <p>
</p>
<pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">native_handle</span><span class="special">(</span><span class="identifier">b</span><span class="special">);</span>
</pre>
<p>
                </p>
              </td>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">native_handle_type</span></code>
                </p>
              </td>
<td>
              </td>
</tr>
<tr>
<td>
                <p>
</p>
<pre class="programlisting"><span class="identifier">a</span><span class="special">.</span><span class="identifier">cancel</span><span class="special">(</span><span class="identifier">b</span><span class="special">,</span> <span class="identifier">ec</span><span class="special">);</span>
</pre>
<p>
                </p>
              </td>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">error_code</span></code>
                </p>
              </td>
<td>
                <p>
                  pre: <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span class="identifier">is_open</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span></code>.<br>
                  Causes any outstanding asynchronous operations to complete as soon
                  as possible. Handlers for cancelled operations shall be passed
                  the error code <code class="computeroutput"><span class="identifier">error</span><span class="special">::</span><span class="identifier">operation_aborted</span></code>.
                </p>
              </td>
</tr>
</tbody>
</table></div>
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<td align="right"><div class="copyright-footer">Copyright &#169; 2003-2014 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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