反射、元类 练习

‘‘‘不会3、在元类中控制自定义的类产生的对象相关的属性全部为隐藏属性4、基于元类实现单例模式‘‘‘‘‘‘1、在元类中控制把自定义类的数据属性都变成大写class Father(type):    def __new__(cls,name,bases,dic):        update_dic={}        for k,v in dic.items():            update_dic.update({k.upper():v})        return type.__new__(cls,name,bases,update_dic)

class Son(metaclass=Father):    country=‘China‘    tag=‘Legend of the Dragon‘    def walk(self):        print(‘唐老鸭 is walking‘)

print(Son.__dict__)‘‘‘‘‘‘2、在元类中控制自定义的类无需__init__方法class Father(type):

    def __call__(self, *args, **kwargs):        if args:            raise TypeError(‘must use keyword argument for key function‘)        obj = object.__new__(self)        for k,v in kwargs.items():            obj.__dict__[k.upper()]=v        return obj

class Son(metaclass=Father):    country=‘China‘    tag=‘Legend of the Dragon‘ #龙的传人

    def walk(self):        print(‘唐老鸭 is walking‘)

p=Son(name=‘tank‘,age=18,sex=‘male‘)print(p.__dict__)‘‘‘

原文地址：https://www.cnblogs.com/0B0S/p/12706755.html