[Python-Dev] The path module PEP

[Stefan Rank]

on 26.01.2006 14:15 Paul Moore said the following:
[snip]
> 
> Also note that my example Path("C:", "Windows", "System32") above is
> an *absolute* path on Windows. But a relative (albeit stupidly-named
> :-)) path on Unix. How would that be handled?

wrong, Path("C:", "Windows", "System32") is a relative path on windows.
see below.

> Not that os.path gets it perfect:
> 
> Python 2.4 (#60, Nov 30 2004, 11:49:19) [MSC v.1310 32 bit (Intel)] on win32
> Type "help", "copyright", "credits" or "license" for more information.
>>>> import os
>>>> os.path.join("C:", "Windows", "System32")
> 'C:Windows\\System32'
>>>> os.path.join(".", os.path.join("C:", "Windows", "System32"))
> '.\\C:Windows\\System32'
> 

this is misleading. observe::

  In [1]: import os

  In [2]: os.path.join(".", os.path.join("C:", "Windows", "System32"))
  Out[2]: '.\\C:Windows\\System32'

but::

  In [3]: os.path.join(".", os.path.join("C:\\", "Windows", "System32"))
  Out[3]: 'C:\\Windows\\System32'


The second example uses an absolute path as second argument, and as 
os.path.join should do, the first argument is discarded.

The first case is arguably a bug, since, on windows, C:Windows\System32 
is a path relative to the *current directory on disk C:*
If the cwd on C: would be C:\temp then C:Windows\System32 would point to 
C:\temp\Windows\System32

The problem is that Windows has a cwd per partition...
(I cannot even guess why ;-)

For the sake of illustration, the following is a WinXP cmd session::

  Microsoft Windows XP [Version 5.1.2600]
  (C) Copyright 1985-2001 Microsoft Corp.

  C:\temp>d:

  D:\>cd HOME

  D:\HOME>c:

  C:\temp>d:

  D:\HOME>c:

  C:\temp>cd d:bin

  C:\temp>d:

  D:\HOME\bin>


[snip]
> 
> Arguably, Path objects should always maintain an absolute path - there
> should be no such thing as a relative Path. So you would have

you realise that one might need and/or want to represent a relative path?