signals-slots

May I have a "dangling reference" with the following code (in an eventual slot connected to the myQtSignal)? class Test : public QObject { Q_OBJECT signals: void myQtSignal(const FooObject& obj); public: void sendSignal(const FooObject& fooStackObject) { emit myQtSignal(fooStackObject); } }; void f() { FooObject fooStackObject; Test t; t.sendSignal(fooStackObject); } int main() { f(); std::cin.ignore(); return 0; } Particularly if emit and slot are not executed in the same thread. HostileFork UPDATE 20-APR-2015 Originally I believed that passing a reference to a stack-allocated object would be

I've seen some example code for PySide slots that uses the @QtCore.Slot decorator, and some that does not. Testing it myself, it doesn't seem to make a difference. Is there a reason I should or should not use it? For example, in the following code: import sys from PySide import QtCore # the next line seems to make no difference @QtCore.Slot() def a_slot(s): print s class SomeClass(QtCore.QObject): happened = QtCore.Signal(str) def __init__(self): QtCore.QObject.__init__(self) def do_signal(self): self.happened.emit("Hi.") sc = SomeClass() sc.happened.connect(a_slot) sc.do_signal() the @QtCore

Consider a simple example like this which links two sliders using signals and slots: from PySide.QtCore import * from PySide.QtGui import * import sys class MyMainWindow(QWidget): def __init__(self): QWidget.__init__(self, None) vbox = QVBoxLayout() sone = QSlider(Qt.Horizontal) vbox.addWidget(sone) stwo = QSlider(Qt.Horizontal) vbox.addWidget(stwo) sone.valueChanged.connect(stwo.setValue) if __name__ == '__main__': app = QApplication(sys.argv) w = MyMainWindow() w.show() sys.exit(app.exec_()) How would you change this so that the second slider moves in the opposite direction as the first?

Possible Duplicate: Is it possible to see definition of Q_SIGNALS, Q_SLOT, SLOT(), SIGNAL() macros? (Qt) I couldn't find on Google, the declaration of the macros, SIGNAL and SLOT, in Qt. When we say, connect(button1, SIGNAL (clicked()), this, SLOT (slotButton1())); I would like to understand, which all kinds of parameters does the highlighted macros accept? Any link to doc would be appreciated. EDIT 1 The link I got through Neil's comment below says: #define SLOT(a) "1"#a and what does a represent here? It is not shown in that link. Bart As per the OPs request: As Neil said, the SLOT and

I'm doing some multi-threading. I have a worker class with a work method, which I send into a separate QThread . The work method has a conditioned while loop inside. I want to be able to send a signal to the worker object to stop it (changing the _running condition to false). This will cause the while loop to exit, and a finished signal to be sent from the worker object (which is connected to the quit slot of the worker's thread). The false condition is sent to the worker object via a signal, but it is never received, which I believe is because the while loop blocks the event-loop of its

I want to implement a simple button in PyQt which prints "Hello world" when clicked. How can I do that? I am a real newbie in PyQt. If you're new to PyQt4, there are some useful tutorials on the PyQt Wiki to get you started. But in the meantime, here's your "Hello World" example: from PyQt4 import QtGui, QtCore class Window(QtGui.QWidget): def __init__(self): QtGui.QWidget.__init__(self) self.button = QtGui.QPushButton('Test', self) self.button.clicked.connect(self.handleButton) layout = QtGui.QVBoxLayout(self) layout.addWidget(self.button) def handleButton(self): print ('Hello World') if _