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<div class="refentry">
<a name="boost.signals2.trackable"></a><div class="titlepage"></div>
<div class="refnamediv">
<h2><span class="refentrytitle">Class trackable</span></h2>
<p>boost::signals2::trackable — Provided to ease porting for code using the boost::signals::trackable class from
the original Boost.Signals library.</p>
</div>
<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
<div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: <<a class="link" href="../../signals2/reference.html#header.boost.signals2.trackable_hpp" title="Header <boost/signals2/trackable.hpp>">boost/signals2/trackable.hpp</a>>
</span>
<span class="keyword">class</span> <a class="link" href="trackable.html" title="Class trackable">trackable</a> <span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
<span class="comment">// <a class="link" href="trackable.html#boost.signals2.trackableconstruct-copy-destruct">construct/copy/destruct</a></span>
<a class="link" href="trackable.html#idm45506986914464-bb"><span class="identifier">trackable</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
<a class="link" href="trackable.html#idm45507035931920-bb"><span class="identifier">trackable</span></a><span class="special">(</span><span class="keyword">const</span> <a class="link" href="trackable.html" title="Class trackable">trackable</a><span class="special">&</span><span class="special">)</span><span class="special">;</span>
trackable& <a class="link" href="trackable.html#idm45507161870048-bb"><span class="keyword">operator</span><span class="special">=</span></a><span class="special">(</span><span class="keyword">const</span> <a class="link" href="trackable.html" title="Class trackable">trackable</a><span class="special">&</span><span class="special">)</span><span class="special">;</span>
<a class="link" href="trackable.html#idm45507110165680-bb"><span class="special">~</span><span class="identifier">trackable</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
<span class="special">}</span><span class="special">;</span></pre></div>
<div class="refsect1">
<a name="idm45555129391344"></a><h2>Description</h2>
<p>Use of the <code class="computeroutput">trackable</code> class is not recommended
for new code. The <code class="computeroutput">trackable</code> class is not thread-safe
since <code class="computeroutput">trackable</code> objects disconnect their associated
connections in the <code class="computeroutput">trackable</code> destructor.
Since the <code class="computeroutput">trackable</code> destructor is not run until
after the destructors of any derived classes have completed,
that leaves open a window where a partially destructed
object can still have active connections.
</p>
<p>
The preferred method of automatic connection management
with Boost.Signals2 is to manage the lifetime of
tracked objects with <code class="computeroutput">shared_ptr</code>s and
to use the <a class="link" href="slot.html#idm45506990261536-bb">signals2::slot::track</a>
method to track their lifetimes.</p>
<p>The <code class="computeroutput">trackable</code> class provides automatic
disconnection of signals and slots when objects bound in
slots (via pointer or reference) are destroyed.
<code class="computeroutput">trackable</code> class may only be used as a public
base class for some other class; when used as such, that
class may be bound to function objects used as part of
slots. The manner in which a <code class="computeroutput">trackable</code> object
tracks the set of signal-slot connections it is a part of is
unspecified.</p>
<p>The actual use of <code class="computeroutput">trackable</code> is contingent
on the presence of appropriate
<a class="link" href="../visit_each.html" title="Function template visit_each">visit_each</a> overloads for any
type that may contain pointers or references to trackable
objects.</p>
<div class="refsect2">
<a name="idm45555129379184"></a><h3>
<a name="boost.signals2.trackableconstruct-copy-destruct"></a><code class="computeroutput">trackable</code>
public
construct/copy/destruct</h3>
<div class="orderedlist"><ol class="orderedlist" type="1">
<li class="listitem">
<pre class="literallayout"><a name="idm45506986914464-bb"></a><span class="identifier">trackable</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre>
<div class="variablelist"><table border="0" class="variablelist compact">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term">Effects:</span></p></td>
<td><p>Sets the list of connected slots to empty.</p></td>
</tr>
<tr>
<td><p><span class="term">Throws:</span></p></td>
<td><p>Will not throw.</p></td>
</tr>
</tbody>
</table></div>
</li>
<li class="listitem">
<pre class="literallayout"><a name="idm45507035931920-bb"></a><span class="identifier">trackable</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="trackable.html" title="Class trackable">trackable</a><span class="special">&</span> other<span class="special">)</span><span class="special">;</span></pre>
<div class="variablelist"><table border="0" class="variablelist compact">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term">Effects:</span></p></td>
<td><p>Sets the list of connected slots to empty.</p></td>
</tr>
<tr>
<td><p><span class="term">Throws:</span></p></td>
<td><p>Will not throw.</p></td>
</tr>
<tr>
<td><p><span class="term">Rationale:</span></p></td>
<td><p>Signal-slot connections can only be created via calls to an explicit connect method, and therefore cannot be created here when trackable objects are copied.</p></td>
</tr>
</tbody>
</table></div>
</li>
<li class="listitem">
<pre class="literallayout">trackable& <a name="idm45507161870048-bb"></a><span class="keyword">operator</span><span class="special">=</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="trackable.html" title="Class trackable">trackable</a><span class="special">&</span> other<span class="special">)</span><span class="special">;</span></pre>
<div class="variablelist"><table border="0" class="variablelist compact">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term">Effects:</span></p></td>
<td><p>Sets the list of connected slots to empty.</p></td>
</tr>
<tr>
<td><p><span class="term">Returns:</span></p></td>
<td><p><code class="computeroutput">*this</code></p></td>
</tr>
<tr>
<td><p><span class="term">Throws:</span></p></td>
<td><p>Will not throw.</p></td>
</tr>
<tr>
<td><p><span class="term">Rationale:</span></p></td>
<td><p>Signal-slot connections can only be created via calls to an explicit connect method, and therefore cannot be created here when trackable objects are copied.</p></td>
</tr>
</tbody>
</table></div>
</li>
<li class="listitem">
<pre class="literallayout"><a name="idm45507110165680-bb"></a><span class="special">~</span><span class="identifier">trackable</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre>
<div class="variablelist"><table border="0" class="variablelist compact">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody><tr>
<td><p><span class="term">Effects:</span></p></td>
<td><p>Disconnects all signal/slot connections that
contain a pointer or reference to this trackable object that
can be found by
<a class="link" href="../visit_each.html" title="Function template visit_each">visit_each</a>.</p></td>
</tr></tbody>
</table></div>
</li>
</ol></div>
</div>
</div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright © 2001-2004 Douglas Gregor<br>Copyright © 2007-2009 Frank Mori Hess<p>Distributed under the Boost
Software License, Version 1.0. (See accompanying file
<code class="filename">LICENSE_1_0.txt</code> or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)</p>
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