Python 3.6 单例模式 __new__实现

# -----------------------
# __Author : tyran
# __Date : 17-11-14
# -----------------------

class Base:
__instance = None

def __init__(self, num):
self.num = num

def show(self):
print(self.num)

def __new__(cls, *args, **kwargs):
if cls.__instance is None:
cls.__instance = super().__new__(cls)
return cls.__instance

b1 = Base(2)
b1.show()
b2 = Base(3)
b1.show()
b2.show()