item内置函数

class Foo:
    def __getitem__(self, item):
        print('getitem')
        return self.__dict__[item]

    def __setitem__(self, key, value):
        self.__dict__[key] = value

    def __delitem__(self, key):
        print('delitem')
        del self.__dict__[key]

    pass


f1 = Foo()
f1[1] = 3
print(f1.__dict__)
f1['age'] = 27
f1['name'] = '小白'
del f1['name']
print(f1.__dict__)
输出：
{1: 3}
delitem
{1: 3, 'age': 27}

该方法同__getattr__内置方法一样