"return if <expression>"
So yeah, we can "if <expression>: return", but why not? Examples: def some_function(a, b): return if a == b # That will return None return a * b print(some_function(2,2)) # None print(some_function(5,2)) # 10 def some_function_2(a, b): return if a > b or a == b return if a == 1 and b == 1 return a*b print(some_function_2(2,2)) # None print(some_function_2(1,1)) # None print(some_function_2(1,2)) # 2 print(some_function_2(5, 10)) # 50
On Wed, 17 Jun 2020 at 10:44, artem6191 <artem129871@gmail.com> wrote:
So yeah, we can "if <expression>: return", but why not?
That's the wrong question. The correct question is "why is this needed, and is the need sufficiently pressing to justify the change to the language?" You're talking about allowing "return EXPR if CONDITION" as an exact equivalent of "if CONDITION: return EXPR". There isn't even a benefit of "it saves a line of code", so it's very hard to see a justification. Paul
I love the do_stuff if cond syntax in Ruby and in perl. It's very natural to real, much more to follow than if cond: do_stuff But still I don't think that it is enough to demand a language change. Something near this is to have a default of none for A if B else None So we can ommit the else None part, but this goes against the explicit is better than implicit Em qua, 17 de jun de 2020 07:42, Paul Moore <p.f.moore@gmail.com> escreveu:
On 18 Jun 2020, at 13:30, Daniel. <danielhilst@gmail.com> wrote:
I love the do_stuff if cond syntax in Ruby and in perl. It's very natural to real, much more to follow than if cond: do_stuff
I on the other hand hate that syntax and find it harder to read. Why put the code out of sequence? if read_this_1st: read_this_2nd() vs. this that I think of as out of sequence order read_this_2nd() if not read_this_1st Barry
This is very personal preference I don't feel it pythonic but... Ruby make return keywork optional so is very idiomatic (in Ruby) to have multiple onliner early return with this kind of guards at beginning of methods and a "main" case below For me this is just eye preference, we have eyes trained to extract what is important when reading code. There is no absolute more readable that works for everyone IMHO return if cond is more scannable than if cond: return Which need eye to scroll to next line Here is an example of the use case that I'm talking about def foo(): if a: return if B: return if C: return do_stuff() Vs def foo(): return if a return if B return if C do_stuff The second is much more compact And if A: return Well, I'm strongly against these non-indented blocks in python Em qui, 18 de jun de 2020 13:36, Barry Scott <barry@barrys-emacs.org> escreveu:
On Thu, Jun 18, 2020 at 10:00 AM Daniel. <danielhilst@gmail.com> wrote:
is compact good ?!?
if A: return
Well, I'm strongly against these non-indented blocks in python
But why? you nseem to theink the more compact Ruby version is better, so why not the more compact Python version -- the only difference is a colon, and the order: def foo(): if a: return if B: return if C: return which is equally compact, and puts the "meat" of the code up front, which feels more clear and obvious to me. I do use this form myself, in just this situation, where there are multiple cases, and it is compact enough that the return doesn't get lost. That is, I would not do: if ( A and B) or (this > that) and (something in everything): return in that case, the return gets lost out at the end -- even if you don't go beyond 72 chars. anyway, even if it's a slight be more readable to some, it is not worth changing Python over. -CHB
-- Christopher Barker, PhD Python Language Consulting - Teaching - Scientific Software Development - Desktop GUI and Web Development - wxPython, numpy, scipy, Cython
You can already do compact conditional returns with the current syntax: def foo(a, b): return (a != b or None) and a * b or even: foo = (lambda a, b: (a != b or None) and a * b) both return: foo(2, 5) # 10 foo(1, 1) # None ... but clarity would be better. On Fri, Jun 19, 2020 at 4:20 AM Serhiy Storchaka <storchaka@gmail.com> wrote:
On 17/06/2020 10:42, artem6191 wrote:
So yeah, we can "if <expression>: return", but why not?
Because without a decent reason otherwise, status quo ante wins. When I was writing a lot of Perl, I used the "<stmt> if <cond>;" form quite a lot to start with. Partly that was the novelty of it, part was that it reads naturally in English, and part was that I was used to writing ARM assembler (and I do mean ARM, not Thumb) so applying condition codes to every line was a natural if misdirected thing to me. Once the novelty wore off, I found I only used that form when the statement needed serious thought (usually because of a regex) and the condition was an afterthought. For anything I actually cared about, I wanted the visible structuring with line breaks and all. -- Rhodri James *-* Kynesim Ltd
On 6/17/20 5:42 AM, artem6191 wrote:
So yeah, we can "if <expression>: return", but why not?
From Pep 20 (The Zen) There should be one-- and preferably only one --obvious way to do it. We don't add a second way to do something just because we can, there needs to be some clear need that the existing way doesn't handle. -- Richard Damon
On Wed, 17 Jun 2020 at 10:44, artem6191 <artem129871@gmail.com> wrote:
So yeah, we can "if <expression>: return", but why not?
That's the wrong question. The correct question is "why is this needed, and is the need sufficiently pressing to justify the change to the language?" You're talking about allowing "return EXPR if CONDITION" as an exact equivalent of "if CONDITION: return EXPR". There isn't even a benefit of "it saves a line of code", so it's very hard to see a justification. Paul
I love the do_stuff if cond syntax in Ruby and in perl. It's very natural to real, much more to follow than if cond: do_stuff But still I don't think that it is enough to demand a language change. Something near this is to have a default of none for A if B else None So we can ommit the else None part, but this goes against the explicit is better than implicit Em qua, 17 de jun de 2020 07:42, Paul Moore <p.f.moore@gmail.com> escreveu:
On 18 Jun 2020, at 13:30, Daniel. <danielhilst@gmail.com> wrote:
I love the do_stuff if cond syntax in Ruby and in perl. It's very natural to real, much more to follow than if cond: do_stuff
I on the other hand hate that syntax and find it harder to read. Why put the code out of sequence? if read_this_1st: read_this_2nd() vs. this that I think of as out of sequence order read_this_2nd() if not read_this_1st Barry
This is very personal preference I don't feel it pythonic but... Ruby make return keywork optional so is very idiomatic (in Ruby) to have multiple onliner early return with this kind of guards at beginning of methods and a "main" case below For me this is just eye preference, we have eyes trained to extract what is important when reading code. There is no absolute more readable that works for everyone IMHO return if cond is more scannable than if cond: return Which need eye to scroll to next line Here is an example of the use case that I'm talking about def foo(): if a: return if B: return if C: return do_stuff() Vs def foo(): return if a return if B return if C do_stuff The second is much more compact And if A: return Well, I'm strongly against these non-indented blocks in python Em qui, 18 de jun de 2020 13:36, Barry Scott <barry@barrys-emacs.org> escreveu:
On Thu, Jun 18, 2020 at 10:00 AM Daniel. <danielhilst@gmail.com> wrote:
is compact good ?!?
if A: return
Well, I'm strongly against these non-indented blocks in python
But why? you nseem to theink the more compact Ruby version is better, so why not the more compact Python version -- the only difference is a colon, and the order: def foo(): if a: return if B: return if C: return which is equally compact, and puts the "meat" of the code up front, which feels more clear and obvious to me. I do use this form myself, in just this situation, where there are multiple cases, and it is compact enough that the return doesn't get lost. That is, I would not do: if ( A and B) or (this > that) and (something in everything): return in that case, the return gets lost out at the end -- even if you don't go beyond 72 chars. anyway, even if it's a slight be more readable to some, it is not worth changing Python over. -CHB
-- Christopher Barker, PhD Python Language Consulting - Teaching - Scientific Software Development - Desktop GUI and Web Development - wxPython, numpy, scipy, Cython
You can already do compact conditional returns with the current syntax: def foo(a, b): return (a != b or None) and a * b or even: foo = (lambda a, b: (a != b or None) and a * b) both return: foo(2, 5) # 10 foo(1, 1) # None ... but clarity would be better. On Fri, Jun 19, 2020 at 4:20 AM Serhiy Storchaka <storchaka@gmail.com> wrote:
On 17/06/2020 10:42, artem6191 wrote:
So yeah, we can "if <expression>: return", but why not?
Because without a decent reason otherwise, status quo ante wins. When I was writing a lot of Perl, I used the "<stmt> if <cond>;" form quite a lot to start with. Partly that was the novelty of it, part was that it reads naturally in English, and part was that I was used to writing ARM assembler (and I do mean ARM, not Thumb) so applying condition codes to every line was a natural if misdirected thing to me. Once the novelty wore off, I found I only used that form when the statement needed serious thought (usually because of a regex) and the condition was an afterthought. For anything I actually cared about, I wanted the visible structuring with line breaks and all. -- Rhodri James *-* Kynesim Ltd
On 6/17/20 5:42 AM, artem6191 wrote:
So yeah, we can "if <expression>: return", but why not?
From Pep 20 (The Zen) There should be one-- and preferably only one --obvious way to do it. We don't add a second way to do something just because we can, there needs to be some clear need that the existing way doesn't handle. -- Richard Damon
participants (11)
-
artem6191 -
Barry Scott -
Christopher Barker -
Daniel. -
MRAB -
Paul Moore -
Rhodri James -
Richard Damon -
Robert DeLanghe -
Serhiy Storchaka -
Vegard Stikbakke