formatOnType strips spaces in slices where : acts like a binary operator

[brettcannon]

ham[lower+offset : upper+offset]
ham[:upper_fn(x) : step_fn(x)], ham[:: step_fn(x)]
ham[lower + offset : upper + offset]

becomes:

ham[lower + offset:upper + offset]
ham[:upper_fn(x):step_fn(x)], ham[::step_fn(x)]
ham[lower + offset:upper + offset]

Taken from PEP 8 in it's "pet peeves" section.

[MikhailArkhipov]

Yes, this is known. The problem is that there is no good definition - in PEP

ham[lower:upper]

but

ham[lower + offset : upper + offset]

From the grammar perspective, they are both expression:expression syntax. How do we tell? Assume single identifier is not an expression? On the other hand, function calls are also technically expressions, however

ham[: upper_fn(x) : step_fn(x)].

I guess we can special case single identifier or number cases.

[brettcannon]

I'm honestly not too worried about this specific case, especially if it's hard to get right. At worst we just close this as something we simply won't fix so we at least have the issue if someone comes looking for a solution.

[luabud]

Fixed upstream.