[Import-sig] Proposal for a modified import mechanism.

[Prabhu Ramachandran]

Hi,

Sorry about the cross posting.

Over the last couple of weeks I described a problem and inconsistency
with the way Python imports modules.  For more details look at this
thread:

  http://mail.python.org/pipermail/python-list/2001-November/070719.html

In short, currently, import allows one to use non-absolute module
names for modules that are in the current directory.  If a module is
not in the same directory, import then looks for modules in sys.path.
Consequently, dealing with packages that are re-nested is a pain.
Complex package structure also causes problems.  I'd like to note that
I was also not the only person who suffered from this issue -- four
others on mentioned similar problems and some asked me to let them
know if I found a solution.

Subsequently, I proposed another approach that first looks in the
local directory and then walks up the current package tree looking for
modules before looking at sys.path.  I also modified knee.py to obtain
a working solution.  More information is here:

  http://mail.python.org/pipermail/python-list/2001-November/071212.html

the threading is messed up and starts here:

  http://mail.python.org/pipermail/python-list/2001-November/071218.html

You can find the new module and a simple test package here:

  http://av.stanford.edu/~prabhu/download/

There is also a slightly enhanced version of knee.py included that
supports caching module lookup failures suggested by Rainer and Gordon
in:

  http://mail.python.org/pipermail/python-list/2001-November/071218.html

it also fixes a bug where the parent package is an extension module.

I therefore have a working import style that seems to handle importing
packages in a more natural(?) and consistent(?) manner.  I've also
tested it out with a large package like scipy (http://www.scipy.org)
with no trouble or significant performance problems:

  http://mail.python.org/pipermail/python-list/2001-November/071325.html


I'd like to ask the Python developers if they'd consider

    (a) changing the way the current import works to do what I
    proposed, or, 

    (b) add a new keyword like 'rimport' (or something) that does this
    recursive search through parent packages and loads modules.  This
    was actually suggested by Gordon McMillan.  Gordon actually
    suggested something stronger -- import only supports absolute
    names, rimport is relative import and rrimport is a recursive
    relative import.  But this would break the current import since
    import currently aupports some relative lookup.  So maybe import
    and rimport is a workable solution? 

    (c) patch the existing knee.py with my fixes.  Note: these fixes
    have nothing to do with the recirsive module lookup stuff --
    knee.py is merely an improved version of the older one.


Thanks for listening patiently and sorry again for all the cross
posting.

prabhu