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pythonpyqtsignals-slots

defining signal outside __init__ of class doesn't work?

I'm trying to understand signals and slots....

read a couple of things

http://www.harshj.com/2010/05/06/pyqt-faq-custom-signals-jpeg-mouse-hovers-and-more/#custom

http://zetcode.com/tutorials/pyqt4/eventsandsignals/

and here is the question:

class bla(object):
    blaSignal = QtCore.pyqtSignal()

works but

class bla(object):

def __init__(self):
    self.blaSignal = QtCore.pyqtSignal()

doesn't work and it states something about the signal not being bound... What do I not understand here? Why does one work?

Thanks

Solution

  • The problem here is that you want there to be a single signal that's shared by all bla objects.

    If you had a different signal for each bla, nobody would be able to connect up any signal without knowing about the particular bla instance that owned the particular signal. That would be bad enough within the program, but imagine how something like QtDesigner or the QMetaObject-based introspection would handle it. Even if it created a bla instance, that wouldn't be the same bla instance your code created at runtime.

    This is somewhat explained in Defining New Signals with pyqtSignal() in the docs.