[Tutor] Why thus?

[Christian Tismer]

Ok, let's see .-)

> Arthur Siegel wrote:
> 
> Can't quite see what's happening here.
> 
> counter=0
yes, you made a global.

> class Count:
>  def __init__(self):
>     print counter
> Count()

Ok, counter is not defined in Count, and it is
correctly identified as a global.

> counter=0

> class Count:
>  def __init__(self):
>   counter=counter+1
>   print counter
> Count()

The difference is: When compiling your code, the compiler
tries to figure out what is global and what not. Since
counter is assigned to, it becomes a local. But the object
does not yet exist when you request it:
   counter=counter+1
wants to retrieve the current value, and it isn't set yet.
You are accessing a local variable which already has its
slot and is ready to receive a value, but cannot until
it is initialized.

cheers - chris

-- 
Christian Tismer             :^)   <mailto:tismer@appliedbiometrics.com>
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