Having an operand blank or all whitespace is not a common use case for join, nor would it be for my proposed '&' operator. I wanted to present a clear definition, and however I chose it, those corner cases would be non-obvious. That said, I have now withdrawn this proposal due to objections by Bruce Leban and others. Best wishes Rob Cliffe On 11/03/2023 17:13, Antoine Rozo wrote:
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. > _______________________________________________ > Python-ideas mailing list -- python-ideas@python.org > To unsubscribe send an email to python-ideas-leave@python.org > https://mail.python.org/mailman3/lists/python-ideas.python.org/ > Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/A7RPR3... > Code of Conduct: http://python.org/psf/codeofconduct/
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-- Antoine Rozo