How to override an abstract property method without forgetting to add the property decorator in the child class?

Question

I want the Python interpreter to yell at me if I override an abstract property method, but forget to specify that it's still a property method in the child class.

class Parent(metaclass=ABCMeta):
  @property
  @abstractmethod
  def name(self) -> str:
    pass

class Child(Parent):
  @property # If I forget this, I want Python to yell at me.
  def name(self) -> str:
    return 'The Name'

if __name__ == '__main__':
  print(Child().name)

Is there really no built-in way for Python to do this? Must I really create my own decorator to handle this type of behavior?

Answer 1

You could put a runtime check in the Parent's __init__ method, and raise an exception if name is a method.

class Parent(metaclass=ABCMeta):
  def __init__(self):
    assert not callable(self.name)

  @abstractmethod
  def name(self) -> str:
    pass


class GoodChild(Parent):
  @property
  def name(self) -> str:
    return 'The Name'


class BadChild(Parent):
  def name(self) -> str:
    return 'Whoops, not a property'


if __name__ == '__main__':
  good_child = GoodChild()
  print(good_child.name)   # Prints 'The Name'
  bad_child = BadChild()   # Raises an AssertionError when initialized