This link explains the following about the pyqtSlot decorator: Although PyQt4 allows any Python callable to be used as a slot when connecting signals, it is sometimes necessary to explicitly mark a Python method as being a Qt slot and to provide a C++ signature for it. PyQt4 provides the pyqtSlot() function decorator to do … Read more
You can define your own slot (any python callable) and connect that to the signal, then call the other slots from that one slot. class Example(QWidget): def __init__(self): super().__init__() self.initUI() def printLabel(self, str): print(str) def logLabel(self, str): ”’log to a file”’ pass @QtCore.pyqtSlot(int) def on_sld_valueChanged(self, value): self.lcd.display(value) self.printLabel(value) self.logLabel(value) def initUI(self): self.lcd = QLCDNumber(self) self.sld … Read more
It is not possible to mix template and Q_OBJECT but if you have a subset of types you can list the slots and signals like this: class SignalsSlots : public QObject { Q_OBJECT public: explicit SignalsSlots(QObject *parent = 0) : QObject(parent) {} public slots: virtual void writeAsync(int value) {} virtual void writeAsync(float value) {} virtual … Read more
A few weeks ago, we had an intern accidentally connect a signal to a slot more than once. The idea was that under one condition, you’d have the slot connected to the signal, and under another condition you’d disconnect it. When you changed modes, you’d do the appropriate work. Well, he forgot to to disconnect … Read more
OK. So, I did a little more investigating. Seems this is possible. I was able to emit a signal, and receive value from the slot the signal was connected to. But, the problem was that it only returned the last return value from the multiple connected slots: Here’s a simple class definition (main.cpp): #include <QObject> … Read more
There are quite a few problems with your code : like said by Evan the emit keyword is missing all your objects live in the main thread, only the code in the run methods live in other threads, which means that the MySlot slot would be called in the main thread and I’m not sure … Read more
You should use Connections in this case (maybe it’s the only way to connect). Put your object myObj to QML file by setContextProperty qmlVectorForm->rootContext()->setContextProperty(“YourObject”, myOb); Your signal is finishedGatheringDataForItem(QString signalString) In QML file, add Connectios likes below: Connections { target: YourObject onFinishedGatheringDataForItem: { qmlString = signalString } }
You can use the clicked signal because it is only emitted when the user actually clicked the check box, not when you manually check it using setChecked. If you just don’t want the signal to be emitted at one specific time, you can use QObject::blockSignals like this: bool oldState = checkBox->blockSignals(true); checkBox->setChecked(true); checkBox->blockSignals(oldState); The downside … Read more
Slots are a Qt-specific extension of C++. It only compiles after sending the code through Qt’s preprocessor, the Meta-Object Compiler (moc). See http://doc.qt.io/qt-5/moc.html for documentation. Edit: As Frank points out, moc is only required for linking. The extra keywords are #defined away with the standard preprocessor.
Yes, just like regular c++ pure virtual methods. The code generated by MOC does call the pure virtual slots, but that’s ok since the base class can’t be instantiated anyway… Again, just like regular c++ pure virtual methods, the class cannot be instantiated until the methods are given an implementation. One thing: in the subclass, … Read more