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  26 <div class="refentry">
  27 <a name="boost.signals.trackable"></a><div class="titlepage"></div>
  28 <div class="refnamediv">
  29 <h2><span class="refentrytitle">Class trackable</span></h2>
  30 <p>boost::signals::trackable &#8212; Enables safe use of multicast callbacks.</p>
  31 </div>
  32 <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
  33 <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../../signals/reference.html#header.boost.signals.trackable_hpp" title="Header &lt;boost/signals/trackable.hpp&gt;">boost/signals/trackable.hpp</a>&gt;
  34
  35 </span>
  36 <span class="keyword">class</span> <a class="link" href="trackable.html" title="Class trackable">trackable</a> <span class="special">{</span>
  37 <span class="keyword">public</span><span class="special">:</span>
  38   <span class="comment">// <a class="link" href="trackable.html#boost.signals.trackableconstruct-copy-destruct">construct/copy/destruct</a></span>
  39   <a class="link" href="trackable.html#idp718807696-bb"><span class="identifier">trackable</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
  40   <a class="link" href="trackable.html#idp718809328-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">&amp;</span><span class="special">)</span><span class="special">;</span>
  41   trackable&amp; <a class="link" href="trackable.html#idp718814912-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">&amp;</span><span class="special">)</span><span class="special">;</span>
  42   <a class="link" href="trackable.html#idp718813296-bb"><span class="special">~</span><span class="identifier">trackable</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
  43 <span class="special">}</span><span class="special">;</span></pre></div>
  44 <div class="refsect1">
  45 <a name="idp520861424"></a><h2>Description</h2>
  46 <p>The <code class="computeroutput">trackable</code> class provides automatic
  47           disconnection of signals and slots when objects bound in
  48           slots (via pointer or reference) are destroyed. The
  49           <code class="computeroutput">trackable</code> class may only be used as a public
  50           base class for some other class; when used as such, that
  51           class may be bound to function objects used as part of
  52           slots. The manner in which a <code class="computeroutput">trackable</code> object
  53           tracks the set of signal-slot connections it is a part of is
  54           unspecified.</p>
  55 <p>The actual use of <code class="computeroutput">trackable</code> is contingent
  56           on the presence of appropriate
  57           <a class="link" href="../visit_each.html" title="Function template visit_each">visit_each</a> overloads for any
  58           type that may contain pointers or references to trackable
  59           objects.</p>
  60 <div class="refsect2">
  61 <a name="idp520867120"></a><h3>
  62 <a name="boost.signals.trackableconstruct-copy-destruct"></a><code class="computeroutput">trackable</code>
  63         public
  64        construct/copy/destruct</h3>
  65 <div class="orderedlist"><ol class="orderedlist" type="1">
  66 <li class="listitem">
  67 <pre class="literallayout"><a name="idp718807696-bb"></a><span class="identifier">trackable</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre>
  68 <div class="variablelist"><table border="0" class="variablelist compact">
  69 <colgroup>
  70 <col align="left" valign="top">
  71 <col>
  72 </colgroup>
  73 <tbody>
  74 <tr>
  75 <td><p><span class="term">Effects:</span></p></td>
  76 <td><p>Sets the list of connected slots to empty.</p></td>
  77 </tr>
  78 <tr>
  79 <td><p><span class="term">Throws:</span></p></td>
  80 <td><p>Will not throw.</p></td>
  81 </tr>
  82 </tbody>
  83 </table></div>
  84 </li>
  85 <li class="listitem">
  86 <pre class="literallayout"><a name="idp718809328-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">&amp;</span> other<span class="special">)</span><span class="special">;</span></pre>
  87 <div class="variablelist"><table border="0" class="variablelist compact">
  88 <colgroup>
  89 <col align="left" valign="top">
  90 <col>
  91 </colgroup>
  92 <tbody>
  93 <tr>
  94 <td><p><span class="term">Effects:</span></p></td>
  95 <td><p>Sets the list of connected slots to empty.</p></td>
  96 </tr>
  97 <tr>
  98 <td><p><span class="term">Throws:</span></p></td>
  99 <td><p>Will not throw.</p></td>
 100 </tr>
 101 <tr>
 102 <td><p><span class="term">Rationale:</span></p></td>
 103 <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>
 104 </tr>
 105 </tbody>
 106 </table></div>
 107 </li>
 108 <li class="listitem">
 109 <pre class="literallayout">trackable&amp; <a name="idp718814912-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">&amp;</span> other<span class="special">)</span><span class="special">;</span></pre>
 110 <div class="variablelist"><table border="0" class="variablelist compact">
 111 <colgroup>
 112 <col align="left" valign="top">
 113 <col>
 114 </colgroup>
 115 <tbody>
 116 <tr>
 117 <td><p><span class="term">Effects:</span></p></td>
 118 <td><p>Sets the list of connected slots to empty.</p></td>
 119 </tr>
 120 <tr>
 121 <td><p><span class="term">Returns:</span></p></td>
 122 <td><p><code class="computeroutput">*this</code></p></td>
 123 </tr>
 124 <tr>
 125 <td><p><span class="term">Throws:</span></p></td>
 126 <td><p>Will not throw.</p></td>
 127 </tr>
 128 <tr>
 129 <td><p><span class="term">Rationale:</span></p></td>
 130 <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>
 131 </tr>
 132 </tbody>
 133 </table></div>
 134 </li>
 135 <li class="listitem">
 136 <pre class="literallayout"><a name="idp718813296-bb"></a><span class="special">~</span><span class="identifier">trackable</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre>
 137 <div class="variablelist"><table border="0" class="variablelist compact">
 138 <colgroup>
 139 <col align="left" valign="top">
 140 <col>
 141 </colgroup>
 142 <tbody><tr>
 143 <td><p><span class="term">Effects:</span></p></td>
 144 <td><p>Disconnects all signal/slot connections that
 145           contain a pointer or reference to this trackable object that
 146           can be found by
 147           <a class="link" href="../visit_each.html" title="Function template visit_each">visit_each</a>.</p></td>
 148 </tr></tbody>
 149 </table></div>
 150 </li>
 151 </ol></div>
 152 </div>
 153 </div>
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 156 <td align="left"></td>
 157 <td align="right"><div class="copyright-footer">Copyright &#169; 2001-2004 Douglas Gregor<p>Use, modification and distribution is subject to the Boost
 158     Software License, Version 1.0. (See accompanying file
 159     <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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