<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html> <html lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <!-- qobject.cpp --> <title>QSignalBlocker Class | Qt Core 5.9</title> <link rel="stylesheet" type="text/css" href="style/offline-simple.css" /> <script type="text/javascript"> document.getElementsByTagName("link").item(0).setAttribute("href", "style/offline.css"); // loading style sheet breaks anchors that were jumped to before // so force jumping to anchor again setTimeout(function() { var anchor = location.hash; // need to jump to different anchor first (e.g. none) location.hash = "#"; setTimeout(function() { location.hash = anchor; }, 0); }, 0); </script> </head> <body> <div class="header" id="qtdocheader"> <div class="main"> <div class="main-rounded"> <div class="navigationbar"> <table><tr> <td >Qt 5.9</td><td ><a href="qtcore-index.html">Qt Core</a></td><td ><a href="qtcore-module.html">C++ Classes</a></td><td >QSignalBlocker</td></tr></table><table class="buildversion"><tr> <td id="buildversion" width="100%" align="right">Qt 5.9.4 Reference Documentation</td> </tr></table> </div> </div> <div class="content"> <div class="line"> <div class="content mainContent"> <div class="sidebar"> <div class="toc"> <h3><a name="toc">Contents</a></h3> <ul> <li class="level1"><a href="#public-functions">Public Functions</a></li> <li class="level1"><a href="#details">Detailed Description</a></li> </ul> </div> <div class="sidebar-content" id="sidebar-content"></div></div> <h1 class="title">QSignalBlocker Class</h1> <!-- $$$QSignalBlocker-brief --> <p>Exception-safe wrapper around <a href="qobject.html#blockSignals">QObject::blockSignals</a>() <a href="#details">More...</a></p> <!-- @@@QSignalBlocker --> <div class="table"><table class="alignedsummary"> <tr><td class="memItemLeft rightAlign topAlign"> Header:</td><td class="memItemRight bottomAlign"> <span class="preprocessor">#include <QSignalBlocker></span> </td></tr><tr><td class="memItemLeft rightAlign topAlign"> qmake:</td><td class="memItemRight bottomAlign"> QT += core</td></tr><tr><td class="memItemLeft rightAlign topAlign"> Since:</td><td class="memItemRight bottomAlign"> Qt 5.3</td></tr></table></div><ul> <li><a href="qsignalblocker-members.html">List of all members, including inherited members</a></li> </ul> <p><b>Note:</b> All functions in this class are reentrant.</p> <a name="public-functions"></a> <h2 id="public-functions">Public Functions</h2> <div class="table"><table class="alignedsummary"> <tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qsignalblocker.html#QSignalBlocker">QSignalBlocker</a></b>(QObject *<i>object</i>)</td></tr> <tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qsignalblocker.html#QSignalBlocker-1">QSignalBlocker</a></b>(QObject &<i>object</i>)</td></tr> <tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qsignalblocker.html#QSignalBlocker-2">QSignalBlocker</a></b>(QSignalBlocker &&<i>other</i>)</td></tr> <tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qsignalblocker.html#dtor.QSignalBlocker">~QSignalBlocker</a></b>()</td></tr> <tr><td class="memItemLeft rightAlign topAlign"> void </td><td class="memItemRight bottomAlign"><b><a href="qsignalblocker.html#reblock">reblock</a></b>()</td></tr> <tr><td class="memItemLeft rightAlign topAlign"> void </td><td class="memItemRight bottomAlign"><b><a href="qsignalblocker.html#unblock">unblock</a></b>()</td></tr> <tr><td class="memItemLeft rightAlign topAlign"> QSignalBlocker &</td><td class="memItemRight bottomAlign"><b><a href="qsignalblocker.html#operator-eq">operator=</a></b>(QSignalBlocker &&<i>other</i>)</td></tr> </table></div> <a name="details"></a> <!-- $$$QSignalBlocker-description --> <div class="descr"> <h2 id="details">Detailed Description</h2> <p>Exception-safe wrapper around <a href="qobject.html#blockSignals">QObject::blockSignals</a>()</p> <p><a href="qsignalblocker.html">QSignalBlocker</a> can be used whereever you would otherwise use a pair of calls to blockSignals(). It blocks signals in its constructor and in the destructor it resets the state to what it was before the constructor ran.</p> <pre class="cpp"> { <span class="keyword">const</span> <span class="type"><a href="qsignalblocker.html#QSignalBlocker">QSignalBlocker</a></span> blocker(someQObject); <span class="comment">// no signals here</span> } </pre> <p>is thus equivalent to</p> <pre class="cpp"> <span class="keyword">const</span> bool wasBlocked <span class="operator">=</span> someQObject<span class="operator">-</span><span class="operator">></span>blockSignals(<span class="keyword">true</span>); <span class="comment">// no signals here</span> someQObject<span class="operator">-</span><span class="operator">></span>blockSignals(wasBlocked); </pre> <p>except the code using <a href="qsignalblocker.html">QSignalBlocker</a> is safe in the face of exceptions.</p> </div> <p><b>See also </b><a href="qmutexlocker.html">QMutexLocker</a> and <a href="qeventlooplocker.html">QEventLoopLocker</a>.</p> <!-- @@@QSignalBlocker --> <div class="func"> <h2>Member Function Documentation</h2> <!-- $$$QSignalBlocker[overload1]$$$QSignalBlockerQObject* --> <h3 class="fn" id="QSignalBlocker"><a name="QSignalBlocker"></a>QSignalBlocker::<span class="name">QSignalBlocker</span>(<span class="type"><a href="qobject.html">QObject</a></span> *<i>object</i>)</h3> <p>Constructor. Calls <i>object</i>->blockSignals(true).</p> <!-- @@@QSignalBlocker --> <!-- $$$QSignalBlocker$$$QSignalBlockerQObject& --> <h3 class="fn" id="QSignalBlocker-1"><a name="QSignalBlocker-1"></a>QSignalBlocker::<span class="name">QSignalBlocker</span>(<span class="type"><a href="qobject.html">QObject</a></span> &<i>object</i>)</h3> <p>This is an overloaded function.</p> <p>Calls <i>object</i>.blockSignals(true).</p> <!-- @@@QSignalBlocker --> <!-- $$$QSignalBlocker$$$QSignalBlockerQSignalBlocker&& --> <h3 class="fn" id="QSignalBlocker-2"><a name="QSignalBlocker-2"></a>QSignalBlocker::<span class="name">QSignalBlocker</span>(<span class="type"><a href="qsignalblocker.html#QSignalBlocker">QSignalBlocker</a></span> &&<i>other</i>)</h3> <p>Move-constructs a signal blocker from <i>other</i>. <i>other</i> will have a no-op destructor, while repsonsibility for restoring the <a href="qobject.html#signalsBlocked">QObject::signalsBlocked</a>() state is transferred to the new object.</p> <!-- @@@QSignalBlocker --> <!-- $$$~QSignalBlocker[overload1]$$$~QSignalBlocker --> <h3 class="fn" id="dtor.QSignalBlocker"><a name="dtor.QSignalBlocker"></a>QSignalBlocker::<span class="name">~QSignalBlocker</span>()</h3> <p>Destructor. Restores the <a href="qobject.html#signalsBlocked">QObject::signalsBlocked</a>() state to what it was before the constructor ran, unless <a href="qsignalblocker.html#unblock">unblock</a>() has been called without a following <a href="qsignalblocker.html#reblock">reblock</a>(), in which case it does nothing.</p> <!-- @@@~QSignalBlocker --> <!-- $$$reblock[overload1]$$$reblock --> <h3 class="fn" id="reblock"><a name="reblock"></a><span class="type">void</span> QSignalBlocker::<span class="name">reblock</span>()</h3> <p>Re-blocks signals after a previous <a href="qsignalblocker.html#unblock">unblock</a>().</p> <p>The numbers of reblock() and <a href="qsignalblocker.html#unblock">unblock</a>() calls are not counted, so every reblock() undoes any number of <a href="qsignalblocker.html#unblock">unblock</a>() calls.</p> <!-- @@@reblock --> <!-- $$$unblock[overload1]$$$unblock --> <h3 class="fn" id="unblock"><a name="unblock"></a><span class="type">void</span> QSignalBlocker::<span class="name">unblock</span>()</h3> <p>Temporarily restores the <a href="qobject.html#signalsBlocked">QObject::signalsBlocked</a>() state to what it was before this QSignaBlocker's constructor ran. To undo, use <a href="qsignalblocker.html#reblock">reblock</a>().</p> <p>The numbers of <a href="qsignalblocker.html#reblock">reblock</a>() and unblock() calls are not counted, so every unblock() undoes any number of <a href="qsignalblocker.html#reblock">reblock</a>() calls.</p> <!-- @@@unblock --> <!-- $$$operator=[overload1]$$$operator=QSignalBlocker&& --> <h3 class="fn" id="operator-eq"><a name="operator-eq"></a><span class="type"><a href="qsignalblocker.html#QSignalBlocker">QSignalBlocker</a></span> &QSignalBlocker::<span class="name">operator=</span>(<span class="type"><a href="qsignalblocker.html#QSignalBlocker">QSignalBlocker</a></span> &&<i>other</i>)</h3> <p>Move-assigns this signal blocker from <i>other</i>. <i>other</i> will have a no-op destructor, while repsonsibility for restoring the <a href="qobject.html#signalsBlocked">QObject::signalsBlocked</a>() state is transferred to this object.</p> <p>The object's signals this signal blocker was blocking prior to being moved to, if any, are unblocked <i>except</i> in the case where both instances block the same object's signals and <code>*this</code> is unblocked while <i>other</i> is not, at the time of the move.</p> <!-- @@@operator= --> </div> </div> </div> </div> </div> </div> <div class="footer"> <p> <acronym title="Copyright">©</acronym> 2017 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners.<br> The documentation provided herein is licensed under the terms of the <a href="http://www.gnu.org/licenses/fdl.html">GNU Free Documentation License version 1.3</a> as published by the Free Software Foundation.<br> Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners. </p> </div> </body> </html>