abstract static property

abc property staticmethod

Source

• https://stackoverflow.com/a/64397790

• the goal is to have an abstract base class which defines a property that all subclasses must provide
• this property is not dependent on the state of individual class instances, so it should be a static property
• the naive approach using a triple decorated function does not work

from abc import ABC, abstractmethod
 
class Base(ABC):
    @property
    @staticmethod
    @abstractmethod
    def abstract_static_property():
        print("Base.abstract_static_property")
        raise NotImplementedError()

• instead, utilizing __init_subclass__ in the abstract base class, we can emulate the behavior of such an abstract static property

from abc import ABC, abstractmethod
 
class Base(ABC):
    abstract_static_property: T # either specify type or default value
 
    @classmethod
    def __init_subclass__(cls):
        if not any("abstract_static_property" in base.__dict__ for base in cls.__mro__ if base is not Base):
            raise NotImplementedError(
                f"Attribute 'abstract_static_property' has not been overwritten in class '{cls.__name__}'"
            )