python反射，单例模式

反射 4个内置函数分别为:getattr、hasattr、setattr、delattr  获取成员、检查成员、设置成员、删除成员

class Foo():
    def __init__(self,name,age):
        self.name=name
        self.age=age
        #print ('my name is %s' %(self.name))
    def hello(self):
        print ('hello')
ret=Foo('liu',18)
a=getattr(ret,'hello')   
b=hasattr(ret,'hello')
setattr(ret,'name','hi')  #将name由liu修改为hi
a()
print(b)
print(ret.name)
delattr(ret,'hello')