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<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 >QException</td></tr></table><table class="buildversion"><tr>
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<h3><a name="toc">Contents</a></h3>
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<li class="level1"><a href="#public-functions">Public Functions</a></li>
<li class="level1"><a href="#details">Detailed Description</a></li>
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<h1 class="title">QException Class</h1>
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<p>The <a href="qexception.html">QException</a> class provides a base class for exceptions that can transferred across threads. <a href="#details">More...</a></p>
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<tr><td class="memItemLeft rightAlign topAlign"> Header:</td><td class="memItemRight bottomAlign"> <span class="preprocessor">#include <QException></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 5.0</td></tr><tr><td class="memItemLeft rightAlign topAlign"> Inherited By:</td><td class="memItemRight bottomAlign"> <p><a href="qunhandledexception.html">QUnhandledException</a></p>
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<li><a href="qexception-members.html">List of all members, including inherited members</a></li>
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<h2 id="public-functions">Public Functions</h2>
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<tr><td class="memItemLeft rightAlign topAlign"> virtual QException *</td><td class="memItemRight bottomAlign"><b><a href="qexception.html#clone">clone</a></b>() const</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> virtual void </td><td class="memItemRight bottomAlign"><b><a href="qexception.html#raise">raise</a></b>() const</td></tr>
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<h2 id="details">Detailed Description</h2>
<p>The <a href="qexception.html">QException</a> class provides a base class for exceptions that can transferred across threads.</p>
<p>Qt Concurrent supports throwing and catching exceptions across thread boundaries, provided that the exception inherit from <a href="qexception.html">QException</a> and implement two helper functions:</p>
<pre class="cpp">
<span class="keyword">class</span> MyException : <span class="keyword">public</span> <span class="type"><a href="qexception.html">QException</a></span>
{
<span class="keyword">public</span>:
<span class="type">void</span> raise() <span class="keyword">const</span> { <span class="keyword">throw</span> <span class="operator">*</span><span class="keyword">this</span>; }
MyException <span class="operator">*</span>clone() <span class="keyword">const</span> { <span class="keyword">return</span> <span class="keyword">new</span> MyException(<span class="operator">*</span><span class="keyword">this</span>); }
};
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<p><a href="qexception.html">QException</a> subclasses must be thrown by value and caught by reference:</p>
<pre class="cpp">
<span class="keyword">try</span> {
<span class="type"><a href="../qtconcurrent/qtconcurrent.html">QtConcurrent</a></span><span class="operator">::</span>blockingMap(list<span class="operator">,</span> throwFunction); <span class="comment">// throwFunction throws MyException</span>
} <span class="keyword">catch</span> (MyException <span class="operator">&</span>e) {
<span class="comment">// handle exception</span>
}
</pre>
<p>If you throw an exception that is not a subclass of <a href="qexception.html">QException</a>, the Qt functions will throw a <a href="qunhandledexception.html">QUnhandledException</a> in the receiver thread.</p>
<p>When using <a href="qfuture.html">QFuture</a>, transferred exceptions will be thrown when calling the following functions:</p>
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<li><a href="qfuture.html#waitForFinished">QFuture::waitForFinished</a>()</li>
<li><a href="qfuture.html#result">QFuture::result</a>()</li>
<li><a href="qfuture.html#resultAt">QFuture::resultAt</a>()</li>
<li><a href="qfuture.html#results">QFuture::results</a>()</li>
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<h2>Member Function Documentation</h2>
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<h3 class="fn" id="clone"><a name="clone"></a><code>[virtual] </code><span class="type"><a href="qexception.html">QException</a></span> *QException::<span class="name">clone</span>() const</h3>
<p>In your <a href="qexception.html">QException</a> subclass, reimplement clone() like this:</p>
<pre class="cpp">
MyException <span class="operator">*</span>MyException<span class="operator">::</span>clone() <span class="keyword">const</span> { <span class="keyword">return</span> <span class="keyword">new</span> MyException(<span class="operator">*</span><span class="keyword">this</span>); }
</pre>
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<h3 class="fn" id="raise"><a name="raise"></a><code>[virtual] </code><span class="type">void</span> QException::<span class="name">raise</span>() const</h3>
<p>In your <a href="qexception.html">QException</a> subclass, reimplement raise() like this:</p>
<pre class="cpp">
<span class="type">void</span> MyException<span class="operator">::</span>raise() <span class="keyword">const</span> { <span class="keyword">throw</span> <span class="operator">*</span><span class="keyword">this</span>; }
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