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From:	Steve Ward <ward AT csail DOT mit DOT edu>
To:	cygwin AT cygwin DOT com
In-reply-to:	<E1DJHhk-0000GC-VY@cag.csail.mit.edu> (message from Steve Ward on Wed, 06 Apr 2005 17:04:52 -0400)
Subject:	Re: Symlinks don't work in python???
Reply-to:	ward AT mit DOT edu
References:	<E1DJHhk-0000GC-VY AT cag DOT csail DOT mit DOT edu>
Message-Id:	<E1DJxRz-0006OR-8N@cag.csail.mit.edu>
Date:	Fri, 08 Apr 2005 13:39:23 -0400

RE:

   I just upgraded to cygwin 1.5.14 from 1.5.12, and python
   (version 2.4 in both cases) stopped being able to import
   thru symlinks.

   Test case: in a directory containing a symlink to foo.py,

      python
      import foo

   complains "no module named foo.py"; if I copy the file to .,
   it imports fine.  Both worked in previous releases of cygwin.

   Similarly, putting symlinks in site-packages no longer works.

   Has some change to cygwin's handling of symlinks (since 1.5.12)
   caused this problem?

Further exploration of the import-thru-symlink bug in
Cygwin python reveals that:

  (1) Despite the problem with imports, most os.path
      utilities (exists, isfile, islink, isdir) work.

  (2) The one execption I've found is realpath, which
      fails in python 2.4 under cygwin.  It returns
      a path to the symlink, not to the target file.

  (3) Thinking that the realpath bug might be a key
      to the python import-thru-symlinks problem,
      I ran a simple test on recent cygwin/python
      combinations, finding:

      Cygwin version  Python version  realpath  Import
             1.5.xx:           2.yy:    Works?  Works?
      --------------  --------------  --------  ------ 

              1.5.14             2.4        NO      NO
              1.5.13           2.3.4       YES      NO
              1.5.14           2.3.4       YES      NO
              1.5.12             2.4        NO     YES

              Neither bug shows up under Linux.

Interestingly, the realpath and symlink bugs don't
correlate: realpath seems broken in Cygwin python 2.4,
independently of the cygwin package version, while
the import bug shows up in either python version under
cygwin packages since 1.5.13.

Its possible that the problems are python bugs, but they
seem cygwin specific.

The import bug breaks several installations I use (which
configure python via symlinks in site-packages, which no
longer works under cygwin); has nobody else run into this
problem?  I suppose its possible that the bugs are triggered
by something peculiar to the environment of my machines...

Any ideas?

- Steve Ward


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