Assigning to self

[top]

Jeff Shannon wrote:
> class __Foo:
>      "I am a singleton!"
>      pass
>
> def Foo(foo_obj = __Foo()):
>      assert isinstance(foo_obj, __Foo
>      return foo_obj
this is a bit simpler, I think, and takes advantage from Python's free
name-rebinding.

class Singleton(object):
    def __call__(self):
        return self
Singleton = Singleton()

And, now, every time you say obj = Singleton(), you're getting the same
instance. Of course, this corrupt the __call__ method of the class, and
isn't inheritance-safe at all, but if you want only one or two classes
like this, it isn't very much work to implement it. Also, it's free of
weird metaclasses, __new__s, or __dict__ hacks, I think.
Just putting my two-cents into this,
--
 - Alexandre