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

[Dan Villiom Podlaski Christiansen]

On 3 Oct 2010, at 02:35, Nir Soffer wrote:

> On Sat, Sep 25, 2010 at 1:36 AM, James Y Knight <foom at fuhm.net> wrote:
>>
>> An OSX code sketch is available here (summary: call FSPathMakeRef  
>> to get an
>> FSRef from a path string, then FSRefMakePath to make it back into a  
>> path,
>> which will then have the correct case). And note that it only works  
>> if the
>> file actually exists.
>>
>>
>> http://stackoverflow.com/questions/370186/how-do-i-find-the-correct-case-of-a-filename
>>
>> It would indeed be useful to have that be available in Python.
>>
>
> There is a much simpler way:
>
>>>> from Carbon import File
>>>> File.FSRef('/tmp/foo').as_pathname()
> '/private/tmp/Foo'
>
> Note that this is much slower compared to os.path.exists.

This won't work in py3k; the Carbon modules were removed in 3.0. A  
simpler alternative would probably be the F_GETPATH fcntl. An example:

Python 3.1.2 (r312:79147, Jul 11 2010, 18:21:56)
[GCC 4.2.1 (Apple Inc. build 5664)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
 >>> from fcntl import fcntl
 >>> from os.path import basename, exists
 >>> from os import remove
 >>>
 >>> F_GETPATH = 50
 >>>
 >>> if exists('/tmp/å'):
...   remove('/tmp/å')
...
 >>> open('/tmp/å', 'w').close()
 >>> f = open(b'/tmp/A\xcc\x8a')
 >>>
 >>> a = f.name
 >>> b = fcntl(f, F_GETPATH, b'\0' * 1024).rstrip(b'\0')
 >>>
 >>> a, b
(b'/tmp/A\xcc\x8a', b'/private/tmp/\xc3\xa5')
 >>> a.decode('utf-8'), b.decode('utf-8')
('/tmp/Å', '/private/tmp/å')

--

Dan Villiom Podlaski Christiansen
danchr at gmail.com

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