[Python-Dev] commonprefix - the beast just won't die...

[Thomas Wouters]

On Tue, Aug 22, 2000 at 09:45:27AM -0500, Skip Montanaro wrote:

> I reverted the changes to {posix,nt,dos}path.commonprefix this morning,
> updated the tests (still to be checked in) and was starting to work on
> documentation changes, when I realized that something Guido said about using
> dirname to trim to the common directory prefix is probably not correct.
> Here's an example.  The common prefix of ["/usr/local", "/usr/local/bin"] is
> "/usr/local".  If you blindly apply dirname to that (which is what I think
> Guido suggested as the way to make commonprefix do what I wanted, you wind
> up with "/usr", which isn't going to be correct on most Unix flavors.
> Instead, you need to check that the prefix doesn't exist or isn't a
> directory before applying dirname.

And even that won't work, in a case like this:

/home/swenson/
/home/swen/

(common prefix would be /home/swen, which is a directory) or cases like
this:

/home/swenson/
/home/swenniker/

where another directory called
/home/swen

exists.

-- 
Thomas Wouters <thomas@xs4all.net>

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