Lie Ryan <lie.1296@gmail.com> writes:
Steven D'Aprano wrote: <snip>
The only case it doesn't cover is where the second filter depends on the value of x, and even that can be covered with a *tiny* bit more work:
gen = ((x, 3*x**2-5*x+4) for x in seq if x % 3 != 2) result = [y[1] for y in gen if -y[0] < y[1] < y[0]]
It requires no new syntax, no changes to the behaviour of list comps, no new meaning on "as", it's understandable and readable.
I think it would be more readable without index references, but instead using tuple unpacking:: gen = ((x, 3*x**2-5*x+4) for x in seq if x % 3 != 2) result = [b for (a, b) in gen if -a < b < a] It can even be done as a single expression without (IMO) significantly affecting readability:: result = [ b for (a, b) in ((x, 3*x**2-5*x+4) for x in seq if x % 3 != 2) if -a < b < a]
Compare your suggestion:
[3*x**2-5*x+4 as y for x in seq if (x % 3 != 2) and (-x < y < x)]
For me, this one is much clearer, understandable, and readable than y[0] and y[1]; and you still have the option to split them if you think y[0] and y[1] is better.
I hope you'll agree that my above suggestion retains this, without needing any new syntax. -- \ “If you go to a costume party at your boss's house, wouldn't | `\ you think a good costume would be to dress up like the boss's | _o__) wife? Trust me, it's not.” —Jack Handey | Ben Finney