variable scope in list comprehensions

[Piotr Sobolewski]

Hello,

there is something I don't understand about list comprehensions.

I understand how does this work:
print [[y for x in range(8)] for y in range(8)]

However I don't understand why this one works:
print [[y for y in range(8)] for y in range(8)]

In this second example I have one loop nested in another. Both loops uses
the same variable - y. How is it that those loops do not conflict with each
other?

For a moment I thought that maybe list comprehension has its own scope, but
it doesn't seem to be so:
print [[y for y in range(8)] for y in range(8)]
print y

Does anybody understand it?

[Piotr Sobolewski]

Duncan Booth wrote:

For the OP, in some languages (e.g. C) 'for' loops typically calculate
the value of the loop control variable based on some expression
involving the previous value. Python isn't like that. In Python the data
used to compute the next value is stored internally: you cannot access
it directly.

Great! Now everything is clear.

Thanks!