[Python-Dev] os.path.normcase rationale?

Guido van Rossum guido at python.org
Sat Sep 25 01:22:47 CEST 2010

I think that, like os.path.realpath(), it should not fail if the file
does not exist.

Maybe the API could be called os.path.unnormpath(), since it is in a
sense the opposite of normpath() (which removes case) ? But I would
want to write it so that even on Unix it scans the filesystem, in case
the filesystem is case-preserving (like the default fs on OS X).


On Fri, Sep 24, 2010 at 3:43 PM, Glenn Linderman <v+python at g.nevcal.com> wrote:
>  On 9/24/2010 3:10 PM, Greg Ewing wrote:
>> Paul Moore wrote:
>>> I dug into this once, and as far as I could tell, it's possible to get
>>> the information on Windows, but there's no way on Linux to "ask the
>>> filesystem".
>> Maybe we could use a heuristic such as:
>> 1) Search the directory for an exact match to the name given,
>> return it if found.
>> 2) Look for a match ignoring case. If one is found, test it to
>> see if it refers to the same file as the given path, and if so
>> return it.
>> 3) Otherwise, raise an exception.
> Hmm.  There is no need for the function on a case sensitive file system,
> because the name had better be spelled with matching case: that is, if it is
> spelled with non-matching case it is an attempt to reference a non-existent
> file (or at least a different file).
> So the API could do the "right thing" for case preserving or case ignoring
> file systems, but for case sensitive file systems, at most an existence
> check would be warranted.
> In other words, the API, should it be created, should be "What is the actual
> name of the file that matches this if it exists in the filesystem", so the
> first check is to see if it exists in the file system (this may raise an
> exception if it doesn't exist), and then if it does, then on those
> filesystems for which it might be different, obtain the different name.
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--Guido van Rossum (python.org/~guido)

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