Question

Is it a good practice to define properties in an interface like this?

class MyInterface(object):
    def required_method(self):
        raise NotImplementedError

    @property
    def required_property(self):
        raise NotImplementedError

Answer 1

I’d use a ABC class for that, but yes; you can even use a @abstractproperty for that very use-case.

from abc import ABCMeta, abstractproperty, abstractmethod

class MyInterface(object):
    __metaclass__ = ABCMeta

    @abstractmethod
    def required_method(self):
        pass

    @abstractproperty
    def required_property(self):
        pass

Subclasses of the ABC are still free to implement required_property as an attribute instead; the ABC will only verify the existence of required_property, not what type it is.