(Serious?) package namespace problem (and a proposal)

[Bjorn Pettersen]

Note that all the problems you describe completely go away if you do:

  import AAA
  import BBB.AAA

IMHO you deserve any/all complications you get when you do "from foo
import *", and I strongly believe that we shouldn't do _anything_ to
encourage this use...

-- bjorn

Huaiyu Zhu wrote:
> 
> Given the following directory structure,
> 
> python/
>    AAA.py
>    BBB/
>       __init__.py
>       AAA.py
> 
> if sys.path contains 'python', then
> 
> from AAA import *
> from BBB.AAA import *
> 
> would do the right thing at most locations, except when pwd is python/ and
> when '.' is before 'python' in sys.path, in which case they both import from
> python/AAA.py.
> 
> Is this a fair description of current situation?  If so this makes package
> name spaces essentially flat. That is, in order to avoid name clashes one
> has to avoid identical module names even if they are buried deep inside
> packages.  This is even worse on Windows - its file names are caseless - as
> one has to avoid filenames with different cases as well.
> 
> This situation occurs quite often in practice.  For example, AAA could be a
> module for doing something.  BBB could be a wrapper package for doing things
> somewhat differently.  So within BBB/AAA.py one calls 'import AAA' to get
> the real job done, and oops, it imports itself!
> 
> Although it is not advisable to put '.' in path, especially at front, a lot
> of people actually do. And the functionality of a package should not depend
> on this detail.  Otherwise what happens if one imports several packages each
> expecting a different ordering of sys.path?
> 
> In Unix shells, however, this can always be overcome by using absolute
> paths, like /the/absolute/path/command, whatever the PATH is.
> 
> So now to my proposed solution.  Is it possible to have something like this?
> 
> sys.rootpath  = ['/usr/lib/python1.5', '/usr/lib/python1.5/site-packages']
> from rootpath.AAA import *
> from rootpath.BBB.AAA.import *
> 
> This guarantees that module names within packages are well separated.  One
> can still use
> from AAA import *
> to import from any module named AAA that happens to be in the path. IMHO,
> this would not break any existing code (unless it happens to contain the new
> keyword 'rootpath').  It would certainly facilitate much easier use of
> packages. The only real problem I can see of is that developers might (for
> what reason?) rush to occupy real estates under rootpath.  But since the
> standard distribution is centrally controlled and add-ons are user
> controlled, this shouldn't be a big problem.
> 
> --
> Huaiyu Zhu                       hzhu at users.sourceforge.net
> Matrix for Python Project        http://MatPy.sourceforge.net
> --
> http://www.python.org/mailman/listinfo/python-list