Property inheritance done right in Python 3

python_property_inheritance.py

class A:
    def __init__(self):
        self._prop = "bonjour"
    @property
    def prop(self):
        print("A.prop.getter")
        return self._prop
    @prop.setter
    def prop(self, value):
        print("A.prop.setter")
        self._prop = value


class B(A):
    """Override getter and setter"""
    @property
    def prop(self):
        print("B.prop.getter")
        return super().prop  # for getter, you can directly use super().prop
        # return super(B, self.__class__).prop.fget(self)  # although fget would work
    @prop.setter
    def prop(self, value):
        print("B.prop.setter")
        # super().prop = value  # this doesn't work! (AttributeError: 'super' object has no attribute 'prop')
        super(B, self.__class__).prop.fset(self, value)  # for setter, you must use the fset method of the parent class's property


# If you want to override only the getter or setter (but not both), you have to reference the parent class's property in the decorator


class B1(A):
    """Override only getter"""
    @A.prop.getter
    def prop(self):
        print("B1.prop.getter")
        return super().prop
    

class B2(A):
    """Override only setter"""
    @A.prop.setter
    def prop(self, value):
        print("B2.prop.setter")
        super(B2, self.__class__).prop.fset(self, value)


# Note: don't use both '@ParentClass.prop.setter' and '@ParentClass.prop.getter' in a single child class,
# because if the parent class itself inherited the property and only defined either the getter or the setter,
# this can lead to the parent getter or setter not being called (the grandparent getter/setter is directly called).



a = A()
a.prop
# A.prop.getter
# 'bonjour'
a.prop = "au revoir"
# A.prop.setter
a.prop
# A.prop.getter
# 'au revoir'

b = B()
b.prop = "salut"
# B.prop.setter
# A.prop.setter
b.prop
# B.prop.getter
# A.prop.getter
# 'salut'

b1 = B1()
b1.prop = 'only getter'
# A.prop.setter
b1.prop
# B1.prop.getter
# A.prop.getter
# 'only getter'

b2 = B2()
b2.prop = 'only setter'
# B2.prop.setter
# A.prop.setter
b2.prop
# A.prop.getter
# 'only setter'