It's not that tricky to have the lstrip/rstrip behaviour with a join:
def space_join(*args):
first, *middle, last = args
return ' '.join((first.rstrip(), *(s.strip() for s in middle),
last.lstrip()))
What is harder is to be sure that this would be the expected behaviour when
using a `&` operator on strings.
Why `' a' & 'b'` would produce `'a b'` and `' ' & 'b'` produce `' b'`
for example?
Le sam. 11 mars 2023 à 10:04, Rob Cliffe via Python-ideas <
python-ideas@python.org> a écrit :
>
>
> On 07/03/2023 09:54, Valentin Berlier wrote:
> > I'm -1 on this. You can easily make a helper that achieves the desired
> syntax. Presenting "human readable data" isn't just about collapsing
> spaces, and having your own helper means that you can adjust the formatting
> to your specific use case if needed (for example with a different
> separator).
> >
> > from typing import Self
> >
> > class StripJoin:
> > def __init__(self, value: str = "") -> None:
> > self.value = value
> > def __and__(self, other: str) -> Self:
> > other = other.strip()
> > separator = bool(self.value and other) * " "
> > return StripJoin(f"{self.value}{separator}{other}")
> > def __str__(self) -> str:
> > return self.value
> >
> > j = StripJoin()
> > print(j & " foo " & " bar " & " something ")
> > # Output: "foo bar something"
> >
> > The example above is more efficient than a possible implementation
> directly on the str builtin as it doesn't strip the left side over and
> over. However it still incurs repeated allocations and encourages a pattern
> that performs badly in loops. With a lot of input you should probably
> accumulate the stripped strings in a list and join them all at once.
> As Steven d'Aprano pointed out re a similar suggestion, this is not the
> same as my proposal, where
> " foo " & " bar " & " something "
> would evaluated to
> " foo bar something "
> Far from stripping the left side over and over, it doesn't strip it at
> all! (Or the right side.)
> This is trickier to write using join. And if the first or last string
> can be blank, or all whitespace, it is trickier still.
> As it is so easy to get these things wrong, perhaps having it built in
> is not such a terrible idea?😁
> Best wishes
> Rob Cliffe
> >
> > In any case I recommend reaching out for a library like Rich (
> https://github.com/Textualize/rich) if you care about formatting the
> output of your program nicely.
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--
Antoine Rozo
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