What is the rationale behind use-maxsplit-arg?

[tmccall8829]

Question

I have a python script that includes the following line:

"/my/endpoint".split("/")[-1]

When I run my script through pylint, it hits me with a use-maxsplit-arg warning and suggests I do the following instead:

"/my/endpoint".rsplit("/", maxsplit=1)[-1]

What I'm wondering is, what is the rationale behind that rule? It seems unnecessarily complex, and when I time things with timeit it looks like the recommended change actually takes slightly longer to execute than the original:

python -m timeit '"/my/endpoint".split("/")[-1]'
2000000 loops, best of 5: 124 nsec per loop

python -m timeit '"/my/endpoint".rsplit("/", maxsplit=1)[-1]'
2000000 loops, best of 5: 154 nsec per loop

Thanks!

Documentation for future user

This might already exist, but it'd be nice if there was an easy to access "rationale guide" behind some of these rules. Like I said, maybe that already exists but I wasn't able to find it quickly. I don't want to just make pylint ignore a rule because I don't understand it, but this one comes up often and I've never been able to figure out the rationale.

Additional context

No response

[jacobtylerwalls]

I wasn't involved in reviewing that checker, but it looks like speed was the reason. You can imagine this making a bigger difference with a larger string:

>>> search_term = 'my/endpoint'
>>> timeit("search_term.split('/')[-1]", globals=globals())
0.085186209063977
>>> timeit("search_term.rsplit('/', maxsplit=1)[-1]", globals=globals())
0.11102708312682807
>>> search_term = 'my/endpoint' * 50
>>> timeit("search_term.split('/')[-1]", globals=globals())
1.1893660409841686
>>> timeit("search_term.rsplit('/', maxsplit=1)[-1]", globals=globals())
0.1747692502103746

We're working on a documentation project to provide a page for each message. I could envision adding a sentence about this there, acknowledging that there is negligible or even worse performance impact with such small strings. I'll just open that PR to get it going.