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POHow to emit cross-thread signal in Qt?
 

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  1. POHow to emit cross-thread signal in Qt?
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    <p>Qt documentation states that signals and slots can be <code>direct</code>, <code>queued</code> and <code>auto</code>. </p> <p>It also stated that if object that owns slot 'lives' in a thread different from object that owns signal, emitting such signal will be like posting message - signal emit will return instantly and slot method will be called in target thread's event loop. </p> <p>Unfortunately, documentation do not specify that 'lives' stands for and no examples is available. I have tried the following code:</p> <p><strong><code>main.h:</code></strong></p> <pre><code>class CThread1 : public QThread { Q_OBJECT public: void run( void ) { msleep( 200 ); std::cout &lt;&lt; "thread 1 started" &lt;&lt; std::endl; MySignal(); exec(); } signals: void MySignal( void ); }; class CThread2 : public QThread { Q_OBJECT public: void run( void ) { std::cout &lt;&lt; "thread 2 started" &lt;&lt; std::endl; exec(); } public slots: void MySlot( void ) { std::cout &lt;&lt; "slot called" &lt;&lt; std::endl; } }; </code></pre> <p><strong><code>main.cpp:</code></strong></p> <pre><code>int main(int argc, char *argv[]) { QCoreApplication a(argc, argv); CThread1 oThread1; CThread2 oThread2; QObject::connect( &amp; oThread1, SIGNAL( MySignal() ), &amp; oThread2, SLOT( MySlot() ) ); oThread1.start(); oThread2.start(); oThread1.wait(); oThread2.wait(); return a.exec(); } </code></pre> <p>Output is:</p> <pre><code>thread 2 started thread 1 started </code></pre> <p><code>MySlot()</code> is never called :(. What I'm doing wrong?</p>
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