[Python-Dev] Re: os.path.commonprefix breakage

[Guido van Rossum]

I'm reading this tread off-line. I'm feeling responsible because I gave Skip
the green light. I admit that that was a mistake: I didn't recall the
purpose of commonprefix() correctrly, and didn't refresh my memory by
reading the docs. I think Tim is right: as the docs say, the function was
*intended* to work on a character basis. This doesn't mean that it doesn't
belong in os.path! Note that os.dirname() will reliably return the common
directory, exactly because the trailing slash is kept.

I propose:

- restore the old behavior on all platforms
- add to the docs that to get the common directory you use dirname()
- add testcases that check that this works on all platforms

- don't add commonpathprefix(), because dirname() already does it

Note that I've only read email up to Thursday morning. If this has been
superseded by more recent resolution, I'll reconsider; but if it's still up
in the air this should be it.

It doesn't look like the change made it into 1.6.

--Guido