如何使用描述符对实例属性做类型检查

分别实现__get__,__set__,__delete__方法，在__set__内使用isinstance函数做类型检查

# 如何使用描述符对实例属性做类型检查,分别实现set,方法,
# 在set内使用isinstance做类型检查
class Attr(object):
    def __init__(self, name, type_):
        self.name = name
        self.type_ = type_

    def __get__(self, instance, cls):
        print('in__get__', instance, cls)
        return instance.__dict__[self.name]

    def __set__(self, instance, value):
        print('in__set__')
        if not isinstance(value, self.type_):
            raise TypeError("expacted is %s" % (self.type_))
        instance.__dict__[self.name] = value

    def __delete__(self, instance):
        print('in__delete__')
        del instance.__dict__[self.name]


class Person(object):
    name = Attr('name', str)
    age = Attr('age', int)
    height = Attr('height', float)


p = Person()
p.name = 'oobj'
p.age = 26

print(p.name)
print(p.age)