TypedProperty

class TypedProperty:

    _VALUE_PREFIX = '_tpvalue_'

    def __init__(self, _type):
        self._type = _type


    def __get__(self, instance, cls):
        if instance is None:
            return cls.__dict__[self.name]
        if self.name not in instance.__dict__:
            return cls.__dict__[TypedProperty._VALUE_PREFIX+self.name]
        return instance.__dict__[self.name]




    def __set__(self, instance, value):
        print('set')
        if not isinstance(value, self._type):
            raise ValueError(f'attribute {self.name!r} must be {self._type.__name__}, but got {value.__class__.__name__} instead.')
        if instance is None:
            print('hey')
        if self.name in instance.__dict__:
            instance.__dict__[self.name] = value
        else:
            setattr(instance.__class__, TypedProperty._VALUE_PREFIX+self.name, value)



    def __delete__(self, instance):
        self.__set__(instance, self._type())


    def __set_name__(self, cls, name):
        print('set name')
        self.name = name
        setattr(cls, TypedProperty._VALUE_PREFIX+name, self._type())
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