Nested scopes hitch

[Jeff Shannon]

In article <a8kn23$ikq$1 at zeus.polsl.gliwice.pl>, 
maug at poczta.onet.pl says...
> 
> class A:
>     a = 1
>     def f():
>         print a
>     f()
> Traceback (most recent call last):
[...]
> NameError: global name 'a' is not defined
> 
> def f1():
>     a = 1
>     def f2():
>         print a
>     f2()
> f1()
[...]
> 1

The difference here is because of the class statement, it's not 
using nested scopes in the sense that you're thinking.  In class 
A, the attribute a is a class attribute, not a name in an 
enclosing scope, so the nested scope rules don't apply.  You can 
access it by referring to self.a, however -- that will find both 
instance and class attributes.  

>>> class A:
... 	a = 1
... 	def f(self):
... 		print self.a
... 	
>>> obj = A()
>>> obj.f()
1
>>>

However, for your desired purpose -- a singleton "class" with no 
instances -- you're probably better off putting your code in a 
separate module, and importing the module wherever needed-- as 
noted in another thread today, a module is already a singleton.

-- 

Jeff Shannon
Technician/Programmer
Credit International