Odd name shadowing in comprehension

[Chris Angelico]

On Sun, Oct 23, 2016 at 4:08 PM, eryk sun <eryksun at gmail.com> wrote:
> For generator expressions, it's about early binding of the outer
> iterator. This makes the result of the expression for the outer
> iterator behave like a function parameter. Obviously it has to be
> evaluated in the defining scope. Comprehensions have adopted the same
> behavior, and it's not a bug or a flawed design. However it does need
> to be documented better in section 6.2.4.

It may not be flawed design, but it's certainly unintuitive, given the
normal explanation:

gen = ((x,y) for x in range(y) for y in range(z))

def g():
    for x in range(y):
        for y in range(z):
            yield (x,y)
gen = g()

It's actually this, which is definitely unintuitive:

def g(it):
    for x in it:
        for y in range(z):
            yield (x,y)
gen = g(iter(range(y)))

Do you ever see them explained like that? Me neither. So if it's
intentional, it needs to be explained somewhere, unless the assumption
is that it'll almost never matter.

ChrisA