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| <div class="titlepage"><div><div><h3 class="title"> |
| <a name="boost_asio.reference.Handler"></a><a class="link" href="Handler.html" title="Handlers">Handlers</a> |
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| <p> |
| A handler must meet the requirements of <code class="computeroutput"><span class="identifier">CopyConstructible</span></code> |
| types (C++ Std, 20.1.3). |
| </p> |
| <p> |
| In the table below, <code class="computeroutput"><span class="identifier">X</span></code> denotes |
| a handler class, <code class="computeroutput"><span class="identifier">h</span></code> denotes |
| a value of <code class="computeroutput"><span class="identifier">X</span></code>, <code class="computeroutput"><span class="identifier">p</span></code> denotes a pointer to a block of allocated |
| memory of type <code class="computeroutput"><span class="keyword">void</span><span class="special">*</span></code>, |
| <code class="computeroutput"><span class="identifier">s</span></code> denotes the size for a |
| block of allocated memory, and <code class="computeroutput"><span class="identifier">f</span></code> |
| denotes a function object taking no arguments. |
| </p> |
| <div class="table"> |
| <a name="id834744"></a><p class="title"><b>Table 13. Handler requirements</b></p> |
| <div class="table-contents"><table class="table" summary="Handler 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-conditions |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">;</span> |
| <span class="identifier">asio_handler_allocate</span><span class="special">(</span><span class="identifier">s</span><span class="special">,</span> <span class="special">&</span><span class="identifier">h</span><span class="special">);</span> |
| </pre> |
| <p> |
| </p> |
| </td> |
| <td> |
| <p> |
| <code class="computeroutput"><span class="keyword">void</span><span class="special">*</span></code> |
| </p> |
| </td> |
| <td> |
| <p> |
| Returns a pointer to a block of memory of size <code class="computeroutput"><span class="identifier">s</span></code>. |
| The pointer must satisfy the same alignment requirements as a pointer |
| returned by <code class="computeroutput"><span class="special">::</span><span class="keyword">operator</span> |
| <span class="keyword">new</span><span class="special">()</span></code>. |
| Throws <code class="computeroutput"><span class="identifier">bad_alloc</span></code> |
| on failure.<br> <br> The <code class="computeroutput"><span class="identifier">asio_handler_allocate</span><span class="special">()</span></code> function is located using argument-dependent |
| lookup. The function <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">asio_handler_allocate</span><span class="special">()</span></code> serves as a default if no user-supplied |
| function is available. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">;</span> |
| <span class="identifier">asio_handler_deallocate</span><span class="special">(</span><span class="identifier">p</span><span class="special">,</span> <span class="identifier">s</span><span class="special">,</span> <span class="special">&</span><span class="identifier">h</span><span class="special">);</span> |
| </pre> |
| <p> |
| </p> |
| </td> |
| <td> |
| </td> |
| <td> |
| <p> |
| Frees a block of memory associated with a pointer <code class="computeroutput"><span class="identifier">p</span></code>, of at least size <code class="computeroutput"><span class="identifier">s</span></code>, that was previously allocated |
| using <code class="computeroutput"><span class="identifier">asio_handler_allocate</span><span class="special">()</span></code>.<br> <br> The <code class="computeroutput"><span class="identifier">asio_handler_deallocate</span><span class="special">()</span></code> |
| function is located using argument-dependent lookup. The function |
| <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">asio_handler_deallocate</span><span class="special">()</span></code> |
| serves as a default if no user-supplied function is available. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">;</span> |
| <span class="identifier">asio_handler_invoke</span><span class="special">(</span><span class="identifier">f</span><span class="special">,</span> <span class="special">&</span><span class="identifier">h</span><span class="special">);</span> |
| </pre> |
| <p> |
| </p> |
| </td> |
| <td> |
| </td> |
| <td> |
| <p> |
| Causes the function object <code class="computeroutput"><span class="identifier">f</span></code> |
| to be executed as if by calling <code class="computeroutput"><span class="identifier">f</span><span class="special">()</span></code>.<br> <br> The <code class="computeroutput"><span class="identifier">asio_handler_invoke</span><span class="special">()</span></code> |
| function is located using argument-dependent lookup. The function |
| <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">asio_handler_invoke</span><span class="special">()</span></code> |
| serves as a default if no user-supplied function is available. |
| </p> |
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| </tr> |
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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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