class Foo:

    def __init__(self, name):

        self.name = name



    def __getitem__(self, item):

        print('obj[key]时，我执行')

        print(self.__dict__[item])

    def __setitem__(self, key, value):

        print('obj[key]=value时，我执行')

        self.__dict__[key] = value

    def __delitem__(self, key):

        print('del obj[key]时,我执行')

        self.__dict__.pop(key)

    def __delattr__(self, item):

        print('del obj.key时,我执行')

        self.__dict__.pop(item)

f1 = Foo('jack')

f1['name']  # obj[key]时，我执行  # jack

f1['age'] = 18  # obj[key]=value时，我执行

f1['age2'] = 19  # # obj[key]=value时，我执行

del f1.age  # del obj.key时,我执行

del f1['age2']  # del obj[key]时,我执行

f1['name'] = 'alex'  # f1[key]=value时，我执行

print(f1.__dict__)  # {'name': 'alex'}