[Tutor] help on scope

[ak@silmarill.org]

On Sun, Jul 22, 2001 at 07:33:50PM +0200, Charlie Clark wrote:
> Consider this:
> 
> count = 0
> 
> def func(something):
>     print count
>     count += 1
> 
> This will print 0 but generate an error about the assignment. I know this is 
> a scope problem but my brain is having trouble with accepting the fact that 
> although I can access a variable I can't reference it. Do I have to use 
> global to get around this? How does global actually work?

You can reference it, you just can't change it. Think of it as a safety
mechanism, because, well, it is :-). 

> 
> def func(something):
>     global count
>     print count
>     count += 1

That's the accepted way of changing it.. Also, you can do this:

class my_class: pass

inst = my_class() # inst means 'instance', as in, "this classes' instance"

inst.count = 0

inst.count += 1

def func(something):
    print inst.count
    inst.count += 1

I personally use globals very rarely, 5 or so at most in a medium sized
program. Using instance members somehow 'feels' cleaner.

> 
> Thanx for any help.
> 
> Charlie
> -- 
> Charlie Clark
> Helmholtzstr. 20
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> D- 40215
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> 
> 
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