[Python-ideas] str.split with multiple individual split characters

Andy Buckley andy at insectnation.org
Mon Feb 28 01:14:12 CET 2011

Here's another str.split() suggestion, this time an extension (Pythonic,
I think) rather than a change of semantics.

There are cases where, especially in handling user input, I'd like to be
able to treat any of a series of possible delimiters as acceptable.
Let's say that I want commas, underscores, and hyphens to all be treated
as delimiters (as I did in some code I was writing today). I guessed,
based on some other Python std lib behaviours, that this might work:

usertokens = userstr.split([",", "_", "-"])

It doesn't work though, since the sep argument *has* to be a string. I
think it would be nice for an extension like this to be supported,
although I would guess a 90% probability of there being an insightful
reason for why it's not such a great idea after all* ;-)

Unlike many extensions, I don't think that the general solution to this
is *very* quick and idiomatic in current Python. As for a compelling
use-case... well, I'm very sympathetic to not adding functions for which
there is no demand (I forget the relevant acronym) but this is a case
where I suddenly found that I did have that problem to solve and that
Python didn't have the nice built-in answer that I semi-expected it to.
Extension of single arguments to iterables of them is quite a common
Python design feature: one of those things where you think "ooh, this
really is a nice, consistent, powerful language" when you find it. So I
hope that this suggestion finds some favour.

Best wishes,

[*] Such as "how do you distinguish between a string, which is iterable
over its characters, and a list/tuple/blah of individual strings?" Well,
that doesn't strike me as too big a technical issue, but maybe it is.

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