Steven D'Aprano <st...@remove-this-cybersource.com.au> writes:
>> d = dict()
>> for r in [1,2,3]:
>> d[r] = [r for r in [4,5,6]]
>> print d
>
> This isn't directly relevant to your problem, but why use a list
> comprehension in the first place? [r for r in [4,5,6]] is just [4,5,6],
> only slower.
Sure. But I've actually spent some time reducing the real code to a
simple illustration of the problem.
>> THe problem is that the "r" in d[r] somehow captures the value of the
>> "r" in the list comprehension, and somehow kills the loop interator. The
>> (unexpected) result is {6: [4, 5, 6]}.
>
> Actually, no it doesn't kill the loop at all. You have misinterpreted
> what you have seen:
It kills the iterator, not the loop. Sorry, I used 'kill' with the
meaning it has in compiler textbooks: to assign a new value to a
variable.
> It is expected, because list comprehensions leak the variable into the
> enclosing scope.
Thanks.
-- Alain.
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