[Python-Dev] os.path.normcase() in site.py

[Guido van Rossum]

> > I noticed that these days __file__ attributes of modules are case
> > normalized (ie. lowercased on case insensitive file systems), or
> > at least the directory part. Then I noticed that this is caused by
> > the fact that all sys.path entries are case normalized. It turns
> > out that site.py does this, in a function called makepath(), added
> > by Fred about 8 months ago.
> > 
> > I think this is wrong: we should always try to *preserve* case.
> 
> There is an added problem with the makepath() stuff that I hadn't
> reported here yet: it has broken MacPython on some non-western
> machines. Specifically I've had reports of people running a Japanese
> MacOS that things will break if they run Python from a pathname that
> has any non-7-bit-ascii characters in the name. Apparently normcase
> normalizes more than just ascii upper/lowercase letters.
> 
> And aside from that I fully agree with Just: seeing a stacktrace
> with all lowercase filenames is _very_ disconcerting.
> 
> I would disable the case-normalization for MacPython, except that I
> don't know whether it actually has a function. With MacPython's way
> of finding the initial sys.path contents we don't have the
> Windows-Python problem that we add the same directory 5 times (once
> in uppercase, once in lowercase, once in mixed case, once in
> mixed-case with / for \, etc:-), so if this is what it's trying to
> solve we can take it out easily.

I can't think of any function besides the attempt to avoid duplicates.

I think that even on Windows, retaining case makes sense.

I think that there's a way to avoid duplicates without case-folding
everything.  (E.g. use a case-folding comparison instead.)

I wonder if maybe path entries should be normpath'd though?

I'll leave it to Fred, Jack or Just to fix this.

--Guido van Rossum (home page: http://www.python.org/~guido/)