super(type,subclass) in simple singleton implementation
- by Tianchen Wu
when I was implementing naive singleton in python, I came up with a problem with super key word. As usual the behavior of super is always tricky and buggy, hope someone can shed light on it. Thanks :)
The problem is that:
class Singleton(object):
def __new__(cls,*args,**kw):
if not hasattr(cls,'_instance'):
#create a instance of type cls,
origin=super(Singleton,Singleton).__new__(cls,*args,**kw)
cls._instance=origin
return cls._instance
class B(Singleton):
def __init__(self,b):
self.b=b
It actually works, but I am wondering
Will it be better if I change line 5 to the below, like in most of the books?
origin=super(Singleton,cls).__new__(cls,*args,**ks)
what's the difference to make?
