Small correction: isinstance(x, int) should be x.isdigit() in the last example. On Fri, Apr 30, 2021 at 2:14 PM David Álvarez Lombardi < alvarezdqal@gmail.com> wrote:
I appreciate the feedback, but I don't think the proposed ideas address any of my points.
1. *Consistency *(with other comprehensions) 2. *Intuitiveness *(as opposed to str.join(iter) which is widely deemed to be confusing and seemingly-backwards) 3. *Efficiency *(with respect to line count and function calls... though perhaps the cpython implementation could actually avoid the type switching and improve time complexity) 4. *Readability *(due to *much *clearer typing and lack of highly-nested function calls ( f"[{','.join('0123')}]" ) and higher-order functions ( genjoin('', '', '')('0123') )
I would also like readers/commenters to consider the fact that, though I have only provided one use-case, the proposed enhancement would serve as the primary syntax for constructing or filtering a string *when dependent on any other iterable or condition*. I believe this to be an extremely common (almost universal) use-case. Here are just a couple more examples.
new = c"x.lower() for x in old if x in HARDCODED_LIST" # filter-in chars that appear in earlier-defined HARDCODED_LIST and convert to lower new = c"x for x in old if not x.isprintable()" # filter-in non-printable chars new = c"str(int(x) + 1) for x in old if isinstance(x, int)" # increment all integers by 1
To me, it is hard to see how any argument against this design (for anything other than implementation-difficulty or something along these lines) can be anything but an argument against iter comprehensions in general... but if someone disagrees, please say so.
My goal is to *decrease* complexity, and personal/higher-order/nested procedures do not accomplish this in my eyes.
Thank you.
DQAL
On Fri, Apr 30, 2021 at 1:10 PM Jonathan Fine <jfine2358@gmail.com> wrote:
On Fri, Apr 30, 2021 at 6:00 PM Chris Angelico <rosuav@gmail.com> wrote:
For those cases where you're merging literal parts and generated
parts, it may be of value to use an f-string:
f"[{','.join('0123')}]" '[0,1,2,3]'
The part in the braces is evaluated as Python code, and the rest is simple literals.
For readability, reuse and testing I think it often helps to have a function (whose name is meaningful). We can get this via as_list_int_literal = gensep(',', '[', ']')
It would also be nice to allow as_list_int_literal to have a docstring (which could also be used for testing).
I accept that in some cases Chris's ingenious construction has benefits.
-- Jonathan
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