[FIXED] Implement event handlers for QWidget and derived classes and avoid code duplication

Issue

I made a clickable QWidget by inheriting from it as follows in Python (using a Python-Qt binding):

class ClickableWidget(QtGui.QWidget):

    clicked = QtCore.Signal(QtGui.QMouseEvent)

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

    def mousePressEvent(self, event):
        self.clicked.emit(event)

Of course more events and more signals could be implemented.

I want to add the same functionality to QLabel, QToolBar, .. This could of course be done easily the same way resulting in a lot of code duplication.

Is there a better alternative in the sense that there is minimal code duplication and the code is efficient and easy maintainable? What would be the most Qt-like/Pythonic way?

One alternative might be to install an event filter on the Qt-application(?) to filter for all events going to any of the desired widgets but this might get complex by itself having to differentiate between the target objects..

Solution

You could create a function to define the subclasses

def createClickableSubclass(parent):
    class ClickableSubclass(parent):
        clicked_ = QtCore.Signal(QtGui.QMouseEvent)

        def __init__(self, *args, **kwargs):
            super(ClickableSubclass, self).__init__(*args, **kwargs)

        def mousePressEvent(self, event):
            self.clicked_.emit(event)

    return ClickableSubclass


MyLabel = createClickableSubclass(QtGui.QLabel)
MyToolBar = createClickableSubclass(QtGui.QToolBar)

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Edit: with reference to your comment, you would use the subclasses like this:

aLabel = MyLabel('Label text')
aLabel.setStyleSheet('color: yellow')

Answered By - user3419537