[IPython-user]: IPython install under Win2000

[Fernando Perez]

Jerry McRae wrote:

> I agree that USERPROFILE would make more sense.  That would allow
> people to designate a different starting folder for running cmd.exe.
> Of course I rarely do this, since I have a shortcut that runs IPython
> every time I want to access DOS commands.  (:-)

OK, after reading all the responses, here's the solution I've implemented:

def get_home_dir():
     """Return the closest possible equivalent to a 'home' directory.

     We first try $HOME.  Absent that, on NT it's $HOMEDRIVE\$HOMEPATH.

     Currently only Posix and NT are implemented, a HomeDirError exception is
     raised for all other OSes. """

     isdir = os.path.isdir
     env = os.environ
     try:
         homedir = env['HOME']
         if not isdir(homedir):
             # in case a user stuck some string which does NOT resolve to a
             # valid path, it's as good as if we hadn't foud it
             raise KeyError
         return homedir
     except KeyError:
         if os.name == 'posix':
             raise HomeDirError,'undefined $HOME, IPython can not proceed.'
         elif os.name == 'nt':
             # For some strange reason, win9x returns 'nt' for os.name.
             try:
                 homedir = os.path.join(env['HOMEDRIVE'],env['HOMEPATH'])
                 if not isdir(homedir):
                     homedir = os.path.join(env['USERPROFILE'])
                     if not isdir(homedir):
                         raise HomeDirError
                 return homedir
             except:
                 try:
                     # Use the registry to get the 'My Documents' folder.
                     import _winreg as wreg
                     key = wreg.OpenKey(wreg.HKEY_CURRENT_USER,
 
"Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders")
                     homedir = wreg.QueryValueEx(key,'Personal')[0]
                     key.Close()
                     return homedir
                 except:
                     return 'C:\\'
         elif os.name == 'dos':
             # Desperate, may do absurd things in classic MacOS. May work 
under DOS.
             return 'C:\\'
         else:
             raise HomeDirError,'support for your operating system not 
implemented.'

The important change is taken from the pythoncard/python-list suggestion, to 
do an isdir() check first, before using any variable.  This will at least 
catch broken configs like $HOME=='%SOMETHING%' [1].  I am NOT going to go 
hunting a recursive chain of expansions in environment variables, neither am I 
willing to use Alan's one-off test, which is too much of a special hack.

I'm keeping HOMEDRIVE/HOMEPATH first in the priority list, because I don't 
want the behavior to change for existing users.  It would be an unpleasant 
surprise if an ipython update were to spring up a new config somewhere else 
out of the blue.

Unless someone complains soon, this will go into SVN later today.

And many thanks to all for the feedback on this issue.

Best,

f


[1] For the record, yes: I consider an environment variable which expands to 
an unevaluated macro a broken config, period.