单例设计模式

  1. class MusicPlayer(object):
  2.     __instance = None
  3.     __is_first = True
  5.     def __new__(cls, *args, **kwargs):
  6.         if cls.__instance is None:
  7.             cls.__instance = super().__new__(cls)
  9.         return cls.__instance
  11.     def __init__(self, name):
  12.         if self.__is_first:
  13.             self.name = name
  14.             self.__is_first = False
  17. a = MusicPlayer("a")
  18. b = MusicPlayer("b")   #  第二次不会赋值
  20. print(a is b)   # True