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pythonqtpyqtpyqt4signals-slots

What's the difference between @pyqtSignature() and @pyqtSlot() pyqt decorators

I was trying to write a slot that connects to different pyqt signals. What I still can't wrap my head around is the difference between the two decorators @pyqtSignature() and @pyqtSlot().

Example to connect to pyqt clicked signal of QPushButton which is inherited from QAbstractButton, I used the following syntax on_widgetName_signalName, when using @pyqtSignature(""):

@pyqtSignature("")
def on_bn_gpx_select_file_clicked(self):  
    """
    Run when QPushButton is pressed, or do something
    """
    pass

Now when using @pyqtSlot() 

@pyqtSlot()
def on_bn_gpx_select_file_clicked(self):  
    """
    Run when QPushButton is pressed, or do something
    """
    pass

My question is, what is the difference between the two decorators and when should I use @pyqtSignature or @pyqtSlot()

Thanks

Solution

  • The pyqtSignature decorator is part of the old-style signal and slot syntax, which was replaced by the new-style signal and slot syntax in PyQt-4.5.

    Both decorators serve the same purpose, which is to explicitly mark a python method as a Qt slot and specify a C++ signature for it (most commonly in order to select a particular overload). The only relevant difference between the two decorators is that pyqtSlot has a much more pythonic API.

    There should never be any need to use pyqtSignature in new code - it is only really needed for backwards-compatibility.