desc-state-desc.py

class DescState:
    def __init__(self, value):
        self.value = value

    def __get__(self, instance, owner):
        print('DescState get')
        return self.value * 10

    def __set__(self, instance, value):
        print('DescState set')
        self.value


class CalcAttrs:
    X = DescState(2)
    Y = 3

    def __init__(self):
        self.Z = 4


obj = CalcAttrs()
print(obj.X, obj.Y, obj.Z)
obj.X = 5
CalcAttrs.Y = 6
obj.Z = 7
print(obj.X, obj.Y, obj.Z)
obj2 = CalcAttrs()
print(obj2.X, obj2.Y, obj2.Z)