CODEWITHSUNDEEP
pythonpyqt5multiple-inheritancemixinsmetaclass
Bill3000
Bill3000

Reputation: 41

PyQt5: Issues with a Mixin with a metaclass within a derived QWidget class

I'm having issues trying to add a mixin with a metaclass to a class whose base is a QWidget. I'm aware that PyQt5 supports cooperative multiple inheritance and if my MixIn class has no metaclass then things work fine. However, if it has a metaclass - whether it be the pyqtWrapperType metaclass shared by QWidgets or a derived metaclass, then I receive the following error:

Process finished with exit code -1073741819 (0xC0000005)

The code for the rest of the script runs, but the QWidget does not show up. Here's the base code (stripped of the methods since I know they're not necessary for the problem)

import abc, sys
from PyQt5 import QtWidgets, QtCore

# Test Metaclass, will have more if metaclasses work
class MyMeta(abc.ABCMeta, QtCore.pyqtWrapperType):
    def __init__(cls, name, bases, attrs):
        super(MyMeta, cls).__init__(name, bases, attrs)

# MixIn class - ignore the calls to methods for now
# Have same issue if metaclass set to pyqtWrapperType
class LocatorWidget(metaclass=MyMeta):
    def __init__(self, locator=None, name='', parameters={}, **kwargs):
        super().__init__(**kwargs)
        # self.setup_parameters(parameters)
        self.locator = locator
        self.name = name if name else ''
        self.widgetType = self.__class__.__name__.replace('LW', '')
        # self.setup()

# Derived class with a QWidget base
class LWComboBox(QtWidgets.QComboBox, LocatorWidget):
    def __init__(self, locator, **kwargs):
        super().__init__(locator=locator, **kwargs)

def main():
    app = QtWidgets.QApplication(sys.argv)
    # locator is class in full code, using this as filler for now
    locator=[0,1,2,3]
    cb = LWComboBox(locator=locator)
    cb.addItems([str(x) for x in range(5)])
    # Test to see if attribute is set
    print(cb.locator)

    window = QtWidgets.QDialog()
    window.form = QtWidgets.QFormLayout()
    window.form.addRow(cb)
    window.setLayout(window.form)

    window.show()

if __name__ == '__main__':
    main()

I am not having the metaclass conflict error: The base class and derived classes do not have different metaclasses because MyMeta is derived from pyqtWrapperType.

If this process doesn't work I'm wondering if I should stick with my previous idea which was enveloping the widget with the attributes and methods I want to share in a separate class, the widget being one of the attributes, but it'll be nice to subclass QWidgets directly with the necessary abstract methods and attributes.

As an FYI I an running PyCharm 2016.2.3 in Anaconda with PyQt5 version 5.6 (PyQt can't be updated to later versions in Anaconda)

Upvotes: 4

Views: 1833

Answers (1)

ekhumoro
ekhumoro

Reputation: 120698

The pyqtWrapperType no longer exists. If you want the equivalent type in PyQt5, you can use either:

pyqtWrapperType = type(QtCore.QObject)

or:

from sip import wrappertype as pyqtWrapperType

Upvotes: 3

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