The Fun Of Reinvention - Contract 중간 코드

contract.py

class Contract:
    @classmethod
    def check(cls, value):
        pass


class Typed(Contract):
    @classmethod
    def check(cls, value):
        assert isinstance(value, cls.type), f'Expected {cls.type}'
        super().check(value)


class Integer(Typed):
    type = int


class Float(Typed):
    type = float


class String(Typed):
    type = str


class Positive(Contract):
    @classmethod
    def check(cls, value):
        assert value > 0, 'Must be > 0'
        super().check(value)


class PositiveInteger(Integer, Positive):
    pass

PositiveInteger.check(42)  # life the universe and everything
PositiveInteger.check(-1)
PositiveInteger.check("")