CODEWITHSUNDEEP
python-3.xpyqtmultiple-inheritance
Spirine
Spirine

Reputation: 1877

pyqt5 and multiple inheritance

I'd like to create a new class that inherits two subclasses of QWidget. I know multi-inheritance isn't possible in pyqt, but how could I manage to have the properties of both parent classes in one subclass?

What I wish I could do is as follows:

class A(QWidget):

    def __init__(self, widget, parent=None):
        widget.destroyed.connect(self.destroy_handler)

    @pyqtSlot()
    def destroy_handler(self):
        pass

class B (A, QStatusBar):
    def __init__(self, widget, parent=None):
        A.__init__(self, widget)
        QStatusBar.__init__(self, parent)

    @pyqtSlot()
    def destroyed_handler(self):
        print("Destroyed")

Upvotes: 3

Views: 5287

Answers (1)

Spirine
Spirine

Reputation: 1877

I finally found how to do it: first of all, the problems came from A and QStatusBar inheriting QWidget. We can't change QStatusBar, so we must changer A. A shouldn't inherit QWidget: so let's create another class, AInterface, like that:

class AInterface(QObject):
    def __init__(self, a, parent=None)
        super().__init__(parent=parent)
        self.a = a
        self.connect_signal()

    def connect_signal(self, widget):
        widget.destroyed.connect(self.handler)

    @pyqtSlot()
    def handler(self):
        self.a.handler()

A has now the following implementation:

class A:
    def __init__(self, widget):
        a.widget = widget
        a.interface = AInterface(self)

    def handler(self):
        pass

Thus, now we can create subclasses inheriting not only A but also any QObject, like this:

class B(QStatusBar, A):
    def __init__(self, widget, parent=None):
        QStatusBar.__init__(self, parent=parent, wiget=widget)
        A.__init__(self, widget)

    def handler(self):
        self.show('Destroyed', 3000)

Notice the widget=widget in the constructor of QStatusBar: if we don't specify it, a TypeError is thrown...

Upvotes: 7

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