On Jun 19, 2019, at 15:28, Soni L. <fakedme...@gmail.com> wrote:
>
> I'm parsing configs for domain filtering rules, and they come as a list.
> However, str.endswith requires a tuple. So I need to use
> str.endswith(tuple(list)). I don't know the reasoning for this, but why not
> just accept a list as well?
Strings are iterables. So, if endswith could accept arbitrary iterables, then
endswith('abc') would mean the same as endswith(['a', 'b', 'c']), which would
be very confusing.
Or there’d be some special exception so it wouldn’t mean that when the iterable
is a string, which might be less newbie-confusing, but would be even more
confusing when you try to learn the details. (What would the details be?
Remember that there’s also bytes.endswith, and bytearray.endswith, and they
surely don’t want to distinguish with isinstance(arg, str), and even
isinstance(arg, type(self)) is probably a bad idea unless you don’t want a
bytearray to be able to take a bytes argument.)
A better solution would be *args, so you don’t need a single argument that’s
either a string or multiple strings. That’s how newer functions do “one or more
whatevers”. The only problem is that *args didn’t exist at the time endswith
was created (nor did the concept of “arbitrary iterable”).
All of the old functions that do this (and a few newer functions that had good
reasons to exactly ape the API of one of the old functions) use the same
tuple-is-special rule, so you probably wouldn’t want to change one without
changing all of them.
And, if it wasn’t worth changing them in 2.2 or even 3.0 (presumably because
backward compatibility outweighed the benefits), it probably isn’t worth
changing them today either, but maybe you could make a case otherwise.
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