On Jun 21, 2009 1:06pm, Chris Rebert <pyideas@rebertia.com> wrote:
On Sun, Jun 21, 2009 at 10:36 AM, Lie Ryanlie.1296@gmail.com> wrote:
Ben Finney wrote:
Lie Ryan lie.1296@gmail.com> writes:
Steven D'Aprano wrote:
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]
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
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
IMHO, when a comprehension requires more than a single line, it should
turn into explicit loop.
On Sun, Jun 21, 2009 at 1:54 AM, Andrey Popp8mayday@gmail.com> wrote:
What about where/let expression?
[(y, y) for x in some_list if y --
С уважением, Андрей Попп.
+7 911 740 24 91
(A) Please don't top-post. (http://en.wikipedia.org/wiki/Top-post)
(B) That has the distinct disadvantage of adding a new keyword. I
instead prefer the "as" version of the proposal for this reason.
Cheers,
Chris
--
(A) Sorry (B) There is no difference, except "where" is widely used in othe languages. Anyway, I think that "where" like functionality would be useful in list comprehensions, lambdas...