I think `'\n'.join(lines, 1)` & `'\n'.join(lines, 'e')` are worse than
`'\n'.join(lines,
at_end=True)` or others, it's much more complicated to understand what will
be produced.
Le ven. 10 mars 2023 à 00:47, Rob Cliffe via Python-ideas <
python-ideas@python.org> a écrit :
>
>
> On 09/03/2023 05:25, Bruce Leban wrote:
>
>
> On Wed, Mar 8, 2023 at 4:34 PM Rob Cliffe via Python-ideas <
> python-ideas@python.org> wrote:
>
>> It seems to me that it would be useful to be able to make the str.join()
>> function put separators, not only between the items of its operand, but
>> also optionally at the beginning or end.
>> E.g. '|'.join(('Spam', 'Ham', 'Eggs')) returns
>> 'Spam|Ham|Eggs'
>> but it might be useful to make it return one of
>> '|Spam|Ham|Eggs'
>> 'Spam|Ham|Eggs|'
>> '|Spam|Ham|Eggs|'
>>
>
> Compare these two lines:
>
> '\n'.join(lines) + '\n'
> '\n'.join(lines, atEnds=1)
>
>
>
> The first is not only shorter, it's more clear what it's doing. I'd have
> to look up everytime to remember whether the value atEnds=1 is doing the
> right thing. It's just IMHO not valuable enough for the cost. Not every
> potential optimization is worth including in the core language or the
> stdlib (if this even is an optimization).
>
> I don't think your comparison is fair.
> If the second one were written
> '\n'.join(lines, 1)
> it would be shorter. And if it were spelt
> '\n'.join(lines, 'e') # s for at Start, e for at End, b for Both
> which I now think is preferable, it would still be shorter and you
> probably wouldn't need to look it up.
> And when it comes to examples like
> return policy.linesep.join(lines) + policy.linesep
> return policy.linesep.join(lines, 'e')
> it would save even more characters and very likely be (more of) an
> optimisation.
>
> Ben mentions being able to specify if a terminal separator is wanted when
> the list is empty. That is an idea which I think is worth considering.
> How about:
> 'S' = always add a separator at start
> 's' = add a separator at start unless the list is empty
> 'E' = always add a separator at end
> 'e' = add a separator at end unless the list is empty
> with these combinations being allowed:
> 'se, 'SE', 'Se', 'sE'
> (the last two would have the same effect, but the difference in emphasis
> might clarify the author's thought).
> If nothing else, this would push authors into thinking about the empty
> list case, rather than being sloppy about it as Ben suspects in one or two
> cases.
>
> Best wishes
> Rob Cliffe
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--
Antoine Rozo
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