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  # jackf1['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'}