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  26 <div class="refentry">
  27 <a name="boost.signals.connection"></a><div class="titlepage"></div>
  28 <div class="refnamediv">
  29 <h2><span class="refentrytitle">Class connection</span></h2>
  30 <p>boost::signals::connection &#8212; Query/disconnect a signal-slot connection.</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.connection_hpp" title="Header &lt;boost/signals/connection.hpp&gt;">boost/signals/connection.hpp</a>&gt;
  34
  35 </span>
  36 <span class="keyword">class</span> <a class="link" href="connection.html" title="Class connection">connection</a> <span class="special">{</span>
  37 <span class="keyword">public</span><span class="special">:</span>
  38   <span class="comment">// <a class="link" href="connection.html#boost.signals.connectionconstruct-copy-destruct">construct/copy/destruct</a></span>
  39   <a class="link" href="connection.html#idp718825488-bb"><span class="identifier">connection</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
  40   <a class="link" href="connection.html#idp718828736-bb"><span class="identifier">connection</span></a><span class="special">(</span><span class="keyword">const</span> <a class="link" href="connection.html" title="Class connection">connection</a><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
  41   connection&amp; <a class="link" href="connection.html#idp718833280-bb"><span class="keyword">operator</span><span class="special">=</span></a><span class="special">(</span><span class="keyword">const</span> <a class="link" href="connection.html" title="Class connection">connection</a><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
  42
  43   <span class="comment">// <a class="link" href="connection.html#idp718837824-bb">connection management</a></span>
  44   <span class="keyword">void</span> <a class="link" href="connection.html#idp718838384-bb"><span class="identifier">disconnect</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  45   <span class="keyword">bool</span> <a class="link" href="connection.html#idp718843248-bb"><span class="identifier">connected</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  46
  47   <span class="comment">// <a class="link" href="connection.html#idp718847376-bb">blocking</a></span>
  48   <span class="keyword">void</span> <a class="link" href="connection.html#idp718847936-bb"><span class="identifier">block</span></a><span class="special">(</span><span class="keyword">bool</span> <span class="special">=</span> <span class="keyword">true</span><span class="special">)</span><span class="special">;</span>
  49   <span class="keyword">void</span> <a class="link" href="connection.html#idp718852720-bb"><span class="identifier">unblock</span></a><span class="special">(</span><span class="special">)</span><span class="special">;</span>
  50   <span class="keyword">bool</span> <a class="link" href="connection.html#idp718855872-bb"><span class="identifier">blocked</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  51
  52   <span class="comment">// <a class="link" href="connection.html#idp718859408-bb">modifiers</a></span>
  53   <span class="keyword">void</span> <a class="link" href="connection.html#idp718859968-bb"><span class="identifier">swap</span></a><span class="special">(</span><span class="keyword">const</span> <a class="link" href="connection.html" title="Class connection">connection</a><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
  54
  55   <span class="comment">// <a class="link" href="connection.html#idp718865536-bb">comparisons</a></span>
  56   <span class="keyword">bool</span> <a class="link" href="connection.html#idp718866096-bb"><span class="keyword">operator</span><span class="special">==</span></a><span class="special">(</span><span class="keyword">const</span> <a class="link" href="connection.html" title="Class connection">connection</a><span class="special">&amp;</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  57   <span class="keyword">bool</span> <a class="link" href="connection.html#idp718873104-bb"><span class="keyword">operator</span><span class="special">&lt;</span></a><span class="special">(</span><span class="keyword">const</span> <a class="link" href="connection.html" title="Class connection">connection</a><span class="special">&amp;</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  58 <span class="special">}</span><span class="special">;</span>
  59
  60 <span class="comment">// <a class="link" href="connection.html#idp718880336-bb">specialized algorithms</a></span>
  61 <span class="keyword">void</span> <a class="link" href="connection.html#boost.signals.connection.swap_idp718880896"><span class="identifier">swap</span></a><span class="special">(</span><a class="link" href="connection.html" title="Class connection">connection</a><span class="special">&amp;</span><span class="special">,</span> <a class="link" href="connection.html" title="Class connection">connection</a><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span></pre></div>
  62 <div class="refsect1">
  63 <a name="idp520998960"></a><h2>Description</h2>
  64 <p>The <a class="link" href="connection.html" title="Class connection">connection</a> class represents
  65           a connection between a Signal and a Slot. It is a
  66           lightweight object that has the ability to query whether the
  67           signal and slot are currently connected, and to disconnect
  68           the signal and slot. It is always safe to query or
  69           disconnect a connection.</p>
  70 <div class="refsect2">
  71 <a name="idp521001088"></a><h3>
  72 <a name="boost.signals.connectionconstruct-copy-destruct"></a><code class="computeroutput">connection</code>
  73         public
  74        construct/copy/destruct</h3>
  75 <div class="orderedlist"><ol class="orderedlist" type="1">
  76 <li class="listitem">
  77 <pre class="literallayout"><a name="idp718825488-bb"></a><span class="identifier">connection</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre>
  78 <div class="variablelist"><table border="0" class="variablelist compact">
  79 <colgroup>
  80 <col align="left" valign="top">
  81 <col>
  82 </colgroup>
  83 <tbody>
  84 <tr>
  85 <td><p><span class="term">Effects:</span></p></td>
  86 <td><p>Sets the currently represented connection to the
  87           NULL connection.</p></td>
  88 </tr>
  89 <tr>
  90 <td><p><span class="term">Postconditions:</span></p></td>
  91 <td><p><code class="computeroutput">!this-&gt;<a class="link" href="connection.html#idp718843248-bb">connected</a>()</code>.</p></td>
  92 </tr>
  93 <tr>
  94 <td><p><span class="term">Throws:</span></p></td>
  95 <td><p>Will not throw.</p></td>
  96 </tr>
  97 </tbody>
  98 </table></div>
  99 </li>
 100 <li class="listitem">
 101 <pre class="literallayout"><a name="idp718828736-bb"></a><span class="identifier">connection</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="connection.html" title="Class connection">connection</a><span class="special">&amp;</span> other<span class="special">)</span><span class="special">;</span></pre>
 102 <div class="variablelist"><table border="0" class="variablelist compact">
 103 <colgroup>
 104 <col align="left" valign="top">
 105 <col>
 106 </colgroup>
 107 <tbody>
 108 <tr>
 109 <td><p><span class="term">Effects:</span></p></td>
 110 <td><p><code class="computeroutput">this</code> references
 111           the connection referenced by
 112           <code class="computeroutput">other</code>.</p></td>
 113 </tr>
 114 <tr>
 115 <td><p><span class="term">Throws:</span></p></td>
 116 <td><p>Will not throw.</p></td>
 117 </tr>
 118 </tbody>
 119 </table></div>
 120 </li>
 121 <li class="listitem">
 122 <pre class="literallayout">connection&amp; <a name="idp718833280-bb"></a><span class="keyword">operator</span><span class="special">=</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="connection.html" title="Class connection">connection</a><span class="special">&amp;</span> other<span class="special">)</span><span class="special">;</span></pre>
 123 <div class="variablelist"><table border="0" class="variablelist compact">
 124 <colgroup>
 125 <col align="left" valign="top">
 126 <col>
 127 </colgroup>
 128 <tbody>
 129 <tr>
 130 <td><p><span class="term">Effects:</span></p></td>
 131 <td><p><code class="computeroutput">this</code> references
 132           the connection referenced by
 133           <code class="computeroutput">other</code>.</p></td>
 134 </tr>
 135 <tr>
 136 <td><p><span class="term">Throws:</span></p></td>
 137 <td><p>Will not throw.</p></td>
 138 </tr>
 139 </tbody>
 140 </table></div>
 141 </li>
 142 </ol></div>
 143 </div>
 144 <div class="refsect2">
 145 <a name="idp521030512"></a><h3>
 146 <a name="idp718837824-bb"></a><code class="computeroutput">connection</code> connection management</h3>
 147 <div class="orderedlist"><ol class="orderedlist" type="1">
 148 <li class="listitem">
 149 <pre class="literallayout"><span class="keyword">void</span> <a name="idp718838384-bb"></a><span class="identifier">disconnect</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
 150 <div class="variablelist"><table border="0" class="variablelist compact">
 151 <colgroup>
 152 <col align="left" valign="top">
 153 <col>
 154 </colgroup>
 155 <tbody>
 156 <tr>
 157 <td><p><span class="term">Effects:</span></p></td>
 158 <td><p>If
 159              <code class="computeroutput">this-&gt;<a class="link" href="connection.html#idp718843248-bb">connected</a>()</code>,
 160              disconnects the signal and slot referenced by this;
 161              otherwise, this operation is a no-op.</p></td>
 162 </tr>
 163 <tr>
 164 <td><p><span class="term">Postconditions:</span></p></td>
 165 <td><p><code class="computeroutput">!this-&gt;<a class="link" href="connection.html#idp718843248-bb">connected</a>()</code>.</p></td>
 166 </tr>
 167 </tbody>
 168 </table></div>
 169 </li>
 170 <li class="listitem">
 171 <pre class="literallayout"><span class="keyword">bool</span> <a name="idp718843248-bb"></a><span class="identifier">connected</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
 172 <div class="variablelist"><table border="0" class="variablelist compact">
 173 <colgroup>
 174 <col align="left" valign="top">
 175 <col>
 176 </colgroup>
 177 <tbody>
 178 <tr>
 179 <td><p><span class="term">Returns:</span></p></td>
 180 <td><p><code class="computeroutput">true</code> if this
 181             references a non-NULL connection that is still active
 182             (connected), and <code class="computeroutput">false</code>
 183             otherwise.</p></td>
 184 </tr>
 185 <tr>
 186 <td><p><span class="term">Throws:</span></p></td>
 187 <td><p>Will not throw.</p></td>
 188 </tr>
 189 </tbody>
 190 </table></div>
 191 </li>
 192 </ol></div>
 193 </div>
 194 <div class="refsect2">
 195 <a name="idp521051472"></a><h3>
 196 <a name="idp718847376-bb"></a><code class="computeroutput">connection</code> blocking</h3>
 197 <div class="orderedlist"><ol class="orderedlist" type="1">
 198 <li class="listitem">
 199 <pre class="literallayout"><span class="keyword">void</span> <a name="idp718847936-bb"></a><span class="identifier">block</span><span class="special">(</span><span class="keyword">bool</span> should_block <span class="special">=</span> <span class="keyword">true</span><span class="special">)</span><span class="special">;</span></pre>
 200 <div class="variablelist"><table border="0" class="variablelist compact">
 201 <colgroup>
 202 <col align="left" valign="top">
 203 <col>
 204 </colgroup>
 205 <tbody>
 206 <tr>
 207 <td><p><span class="term">Requires:</span></p></td>
 208 <td><code class="computeroutput">connected()</code></td>
 209 </tr>
 210 <tr>
 211 <td><p><span class="term">Postconditions:</span></p></td>
 212 <td><code class="computeroutput">blocked() == should_block</code></td>
 213 </tr>
 214 <tr>
 215 <td><p><span class="term">Throws:</span></p></td>
 216 <td>Will not throw.</td>
 217 </tr>
 218 </tbody>
 219 </table></div>
 220 </li>
 221 <li class="listitem">
 222 <pre class="literallayout"><span class="keyword">void</span> <a name="idp718852720-bb"></a><span class="identifier">unblock</span><span class="special">(</span><span class="special">)</span><span class="special">;</span></pre>
 223 <div class="variablelist"><table border="0" class="variablelist compact">
 224 <colgroup>
 225 <col align="left" valign="top">
 226 <col>
 227 </colgroup>
 228 <tbody>
 229 <tr>
 230 <td><p><span class="term">Requires:</span></p></td>
 231 <td><code class="computeroutput">connected()</code></td>
 232 </tr>
 233 <tr>
 234 <td><p><span class="term">Postconditions:</span></p></td>
 235 <td><code class="computeroutput">!blocked()</code></td>
 236 </tr>
 237 <tr>
 238 <td><p><span class="term">Throws:</span></p></td>
 239 <td>Will not throw.</td>
 240 </tr>
 241 </tbody>
 242 </table></div>
 243 </li>
 244 <li class="listitem">
 245 <pre class="literallayout"><span class="keyword">bool</span> <a name="idp718855872-bb"></a><span class="identifier">blocked</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
 246 <div class="variablelist"><table border="0" class="variablelist compact">
 247 <colgroup>
 248 <col align="left" valign="top">
 249 <col>
 250 </colgroup>
 251 <tbody>
 252 <tr>
 253 <td><p><span class="term">Returns:</span></p></td>
 254 <td>
 255 <code class="computeroutput">true</code> if the associated slot is either disconnected or blocked, <code class="computeroutput">false</code> otherwise.</td>
 256 </tr>
 257 <tr>
 258 <td><p><span class="term">Throws:</span></p></td>
 259 <td>Will not throw.</td>
 260 </tr>
 261 </tbody>
 262 </table></div>
 263 </li>
 264 </ol></div>
 265 </div>
 266 <div class="refsect2">
 267 <a name="idp521080592"></a><h3>
 268 <a name="idp718859408-bb"></a><code class="computeroutput">connection</code> modifiers</h3>
 269 <div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
 270 <pre class="literallayout"><span class="keyword">void</span> <a name="idp718859968-bb"></a><span class="identifier">swap</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="connection.html" title="Class connection">connection</a><span class="special">&amp;</span> other<span class="special">)</span><span class="special">;</span></pre>
 271 <div class="variablelist"><table border="0" class="variablelist compact">
 272 <colgroup>
 273 <col align="left" valign="top">
 274 <col>
 275 </colgroup>
 276 <tbody>
 277 <tr>
 278 <td><p><span class="term">Effects:</span></p></td>
 279 <td><p>Swaps the connections referenced in
 280             <code class="computeroutput">this</code> and
 281             <code class="computeroutput">other</code>.</p></td>
 282 </tr>
 283 <tr>
 284 <td><p><span class="term">Throws:</span></p></td>
 285 <td><p>Will not throw.</p></td>
 286 </tr>
 287 </tbody>
 288 </table></div>
 289 </li></ol></div>
 290 </div>
 291 <div class="refsect2">
 292 <a name="idp521092912"></a><h3>
 293 <a name="idp718865536-bb"></a><code class="computeroutput">connection</code> comparisons</h3>
 294 <div class="orderedlist"><ol class="orderedlist" type="1">
 295 <li class="listitem">
 296 <pre class="literallayout"><span class="keyword">bool</span> <a name="idp718866096-bb"></a><span class="keyword">operator</span><span class="special">==</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="connection.html" title="Class connection">connection</a><span class="special">&amp;</span> other<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
 297 <div class="variablelist"><table border="0" class="variablelist compact">
 298 <colgroup>
 299 <col align="left" valign="top">
 300 <col>
 301 </colgroup>
 302 <tbody>
 303 <tr>
 304 <td><p><span class="term">Returns:</span></p></td>
 305 <td><p><code class="computeroutput">true</code> if
 306             <code class="computeroutput">this</code> and
 307             <code class="computeroutput">other</code> reference the same
 308             connection or both reference the NULL connection, and
 309             <code class="computeroutput">false</code>
 310             otherwise.</p></td>
 311 </tr>
 312 <tr>
 313 <td><p><span class="term">Throws:</span></p></td>
 314 <td><p>Will not throw.</p></td>
 315 </tr>
 316 </tbody>
 317 </table></div>
 318 </li>
 319 <li class="listitem">
 320 <pre class="literallayout"><span class="keyword">bool</span> <a name="idp718873104-bb"></a><span class="keyword">operator</span><span class="special">&lt;</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="connection.html" title="Class connection">connection</a><span class="special">&amp;</span> other<span class="special">)</span> <span class="keyword">const</span><span class="special">;</span></pre>
 321 <div class="variablelist"><table border="0" class="variablelist compact">
 322 <colgroup>
 323 <col align="left" valign="top">
 324 <col>
 325 </colgroup>
 326 <tbody>
 327 <tr>
 328 <td><p><span class="term">Returns:</span></p></td>
 329 <td><p><code class="computeroutput">true</code> if the
 330             connection referenced by
 331             <code class="computeroutput">this</code> precedes the
 332             connection referenced by
 333             <code class="computeroutput">other</code> based on some
 334             unspecified ordering, and
 335             <code class="computeroutput">false</code>
 336             otherwise.</p></td>
 337 </tr>
 338 <tr>
 339 <td><p><span class="term">Throws:</span></p></td>
 340 <td><p>Will not throw.</p></td>
 341 </tr>
 342 </tbody>
 343 </table></div>
 344 </li>
 345 </ol></div>
 346 </div>
 347 <div class="refsect2">
 348 <a name="idp521120592"></a><h3>
 349 <a name="idp718880336-bb"></a><code class="computeroutput">connection</code> specialized algorithms</h3>
 350 <div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem">
 351 <pre class="literallayout"><span class="keyword">void</span> <a name="boost.signals.connection.swap_idp718880896"></a><span class="identifier">swap</span><span class="special">(</span><a class="link" href="connection.html" title="Class connection">connection</a><span class="special">&amp;</span> x<span class="special">,</span> <a class="link" href="connection.html" title="Class connection">connection</a><span class="special">&amp;</span> y<span class="special">)</span><span class="special">;</span></pre>
 352 <div class="variablelist"><table border="0" class="variablelist compact">
 353 <colgroup>
 354 <col align="left" valign="top">
 355 <col>
 356 </colgroup>
 357 <tbody>
 358 <tr>
 359 <td><p><span class="term">Effects:</span></p></td>
 360 <td><p><code class="computeroutput">x.swap(y)</code></p></td>
 361 </tr>
 362 <tr>
 363 <td><p><span class="term">Throws:</span></p></td>
 364 <td><p>Will not throw.</p></td>
 365 </tr>
 366 </tbody>
 367 </table></div>
 368 </li></ol></div>
 369 </div>
 370 </div>
 371 </div>
 372 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 373 <td align="left"></td>
 374 <td align="right"><div class="copyright-footer">Copyright &#169; 2001-2004 Douglas Gregor<p>Use, modification and distribution is subject to the Boost
 375     Software License, Version 1.0. (See accompanying file
 376     <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>
 377 </div></td>
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