Can't use Python dataclass with PyQt5 widget

Question

I've got a class that stores some Qt controls, so:

class Controls:
    def __init__(self):
        self.label = QLabel()

Then I can do:

x = Controls()
x.label.setText("Hello")

This works. The class actually has dozens of controls, not just the one I've used for illustration, so I wanted to use the more succinct dataclass notation:

@dataclass(frozen=True, init=False)
class Controls:
    label: QLabel

but having done this, I get an error:

AttributeError: 'Controls' object has no attribute 'label'

I've tried initialising the field ( = QLabel() ), I've also tried using field with default or default_factory , with no joy.

I wondered if anyone knew what the problem was?

Answer 1

You have to let the constructor be implemented(remove init=False ):

from dataclasses import dataclass, field

@dataclass(frozen=True)
class Controls:
    label: QLabel = field(default_factory=QLabel)