python基础之一：手写单例模式

class SingleTool(object):
	__instance = None
	def __new__(cls,*args,**kwargs):
		if not cls.__instance:
			cls.__instance = object.__new__(cls)
		return cls.__instance

	def addxnum(self,*args):
		my_sum = 0
		for value in args:
			my_sum +=value
		return my_sum
t1 = SingleTool()
print(t1.addxnum(1,2,3))
print(t1)
t2=SingleTool()
print(t2)