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| <div class="titlepage"><div><div><h2 class="title" style="clear: both"> |
| <a name="intrusive.safe_hook"></a><a class="link" href="safe_hook.html" title="Safe hooks">Safe hooks</a> |
| </h2></div></div></div> |
| <div class="toc"><dl> |
| <dt><span class="section"><a href="safe_hook.html#intrusive.safe_hook.features">Features of the safe mode</a></span></dt> |
| <dt><span class="section"><a href="safe_hook.html#intrusive.safe_hook.configuring">Configuring safe-mode |
| assertions</a></span></dt> |
| </dl></div> |
| <div class="section"> |
| <div class="titlepage"><div><div><h3 class="title"> |
| <a name="intrusive.safe_hook.features"></a><a class="link" href="safe_hook.html#intrusive.safe_hook.features" title="Features of the safe mode">Features of the safe mode</a> |
| </h3></div></div></div> |
| <p> |
| <span class="bold"><strong>Boost.Intrusive</strong></span> hooks can be configured |
| to operate in safe-link mode. The safe mode is activated by default, but |
| it can be also explicitly activated: |
| </p> |
| <pre class="programlisting"><span class="comment">//Configuring the safe mode explicitly |
| </span><span class="keyword">class</span> <span class="identifier">Foo</span> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">list_base_hook</span><span class="special"><</span> <span class="identifier">link_mode</span><span class="special"><</span><span class="identifier">safe_link</span><span class="special">></span> <span class="special">></span> |
| <span class="special">{};</span> |
| </pre> |
| <p> |
| With the safe mode the user can detect if the object is actually inserted |
| in a container without any external reference. Let's review the basic features |
| of the safe mode: |
| </p> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc"> |
| <li class="listitem"> |
| Hook's constructor puts the hook in a well-known default state. |
| </li> |
| <li class="listitem"> |
| Hook's destructor checks if the hook is in the well-known default state. |
| If not, an assertion is raised. |
| </li> |
| <li class="listitem"> |
| Every time an object is inserted in the intrusive container, the container |
| checks if the hook is in the well-known default state. If not, an assertion |
| is raised. |
| </li> |
| <li class="listitem"> |
| Every time an object is being erased from the intrusive container, the |
| container puts the erased object in the well-known default state. |
| </li> |
| </ul></div> |
| <p> |
| With these features, without any external reference the user can know if |
| the object has been inserted in a container by calling the <code class="computeroutput"><span class="identifier">is_linked</span><span class="special">()</span></code> |
| member function. If the object is not actually inserted in a container, the |
| hook is in the default state, and if it is inserted in a container, the hook |
| is not in the default state. |
| </p> |
| </div> |
| <div class="section"> |
| <div class="titlepage"><div><div><h3 class="title"> |
| <a name="intrusive.safe_hook.configuring"></a><a class="link" href="safe_hook.html#intrusive.safe_hook.configuring" title="Configuring safe-mode assertions">Configuring safe-mode |
| assertions</a> |
| </h3></div></div></div> |
| <p> |
| By default, all safe-mode assertions raised by <span class="bold"><strong>Boost-Intrusive</strong></span> |
| hooks and containers in are implemented using <code class="computeroutput"><span class="identifier">BOOST_ASSERT</span></code>, |
| which can be configured by the user. See <a href="http://www.boost.org/libs/utility/assert.html" target="_top">http://www.boost.org/libs/utility/assert.html</a> |
| for more information about <code class="computeroutput"><span class="identifier">BOOST_ASSERT</span></code>. |
| </p> |
| <p> |
| <code class="computeroutput"><span class="identifier">BOOST_ASSERT</span></code> is globally |
| configured, so the user might want to redefine intrusive safe-mode assertions |
| without modifying the global <code class="computeroutput"><span class="identifier">BOOST_ASSERT</span></code>. |
| This can be achieved redefining the following macros: |
| </p> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc"> |
| <li class="listitem"> |
| <code class="computeroutput"><span class="identifier">BOOST_INTRUSIVE_SAFE_HOOK_DEFAULT_ASSERT</span></code>: |
| This assertion will be used in insertion functions of the intrusive containers |
| to check that the hook of the value to be inserted is default constructed. |
| </li> |
| <li class="listitem"> |
| <code class="computeroutput"><span class="identifier">BOOST_INTRUSIVE_SAFE_HOOK_DESTRUCTOR_ASSERT</span></code>: |
| This assertion will be used in hooks' destructors to check that the hook |
| is in a default state. |
| </li> |
| </ul></div> |
| <p> |
| If any of these macros is not redefined, the assertion will default to <code class="computeroutput"><span class="identifier">BOOST_ASSERT</span></code>. If <code class="computeroutput"><span class="identifier">BOOST_INTRUSIVE_SAFE_HOOK_DEFAULT_ASSERT</span></code> |
| or <code class="computeroutput"><span class="identifier">BOOST_INTRUSIVE_SAFE_HOOK_DESTRUCTOR_ASSERT</span></code> |
| is defined and the programmer needs to include a file to configure that assertion, |
| it can define <code class="computeroutput"><span class="identifier">BOOST_INTRUSIVE_SAFE_HOOK_DESTRUCTOR_ASSERT_INCLUDE</span></code> |
| or <code class="computeroutput"><span class="identifier">BOOST_INTRUSIVE_SAFE_HOOK_DEFAULT_ASSERT_INCLUDE</span></code> |
| with the name of the file to include: |
| </p> |
| <pre class="programlisting"><span class="preprocessor">#define</span> <span class="identifier">BOOST_INTRUSIVE_SAFE_HOOK_DESTRUCTOR_ASSERT</span> <span class="identifier">MYASSERT</span> |
| <span class="preprocessor">#define</span> <span class="identifier">BOOST_INTRUSIVE_SAFE_HOOK_DESTRUCTOR_ASSERT_INCLUDE</span> <span class="special"><</span><span class="identifier">myassert</span><span class="special">.</span><span class="identifier">h</span><span class="special">></span> |
| </pre> |
| </div> |
| </div> |
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| <td align="left"></td> |
| <td align="right"><div class="copyright-footer">Copyright © 2005 Olaf Krzikalla, 2006-2010 Ion Gaztanaga<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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