Nested module import clutters package namespace?

["Dr. Rüdiger Kupper"]

Hi!

I'd be grateful for help with a problem of package and module 
namespaces. The behaviour I observe is unexpected (to me), and I 
couldn't find the answer in the docs, the tutorial, or the mailing 
list archive. So here we go:

I have a package named 'pack'. Apart from the '__init__.py' file the 
directory contains two modules 'x.py' and 'y.py':

pack/
      __init__.py
      x.py
      y.py

The files have the following contents:

==== __init__.py ====
import x
=====================

==== x.py ===========
import y
=====================

==== y.py ===========
pass
=====================

I then do
 >>> import pack

This
(1) introduces variable 'x' bound to <module 'pack.x'>
     in pack's namespace (expected)
(2) introduces variable 'q' bound to <module 'pack.y'>
     in x's namespace (expected)
but also
(3) introduces variable 'y' bound to <module 'pack.y'>
     in pack's namespace (*totally unexpected*)

The problem is so bad as to even overwrite any variable 'y' that 
might have existed in pack's namespace before the import.

I created verbose versions of the three files above to illustrate 
what happens (see below.) The do exactly the same as above, but 
print out what they do. This is the output:

---------snip-----------
 >>> import pack
pack: Here is pack.
pack: I now assign y='hello'.
pack: My y is now: 'hello'
pack: I now 'import x' which in turn does 'import y as q'.
   x: Here is x.
   x: I now 'import y as q'.
     y: Here is y.
pack: My y is now: <module 'pack.y' from 'pack/y.pyc'>
pack: Why?
--------snip-------------

I know that any import creates an entry in sys.modules. So 'pack', 
'pack.x' and 'pack.y' get created in sys.modules. That's fine.

Apart from that, an import statement should act equivalent to an 
assignment: it should introduce entries to the local namespace of th 
emodule it appears in. The 'import y as q' appears in x.py, so it 
should add entries to x's namespace *only*.

But why is variable 'y' in pack's namespace overwritten by the 
import in x?

Thank you very much in advance,
Best, Rüdiger


P.S.: These are the files that produce the verbose output:

==== __init__.py ====
print "pack: Here is pack."
print "pack: I now assign y='hello'."
y="hello"
print "pack: My y is now:", repr(y)
print "pack: I now 'import x' which in turn does 'import y as q'."
import x
print "pack: My y is now:", repr(y)
print "pack: Why?"
=====================

==== x.py ===========
print '  x: Here is x.'
print "  x: I now 'import y as q'."
import y as q
=====================

==== y.py ===========
print '    y: Here is y.'
=====================

-- 
Dr. Rüdiger Kupper
Honda Research Institute Europe GmbH
Carl-Legien-Straße 30
D-63073 Offenbach/Main, Germany

Phone : +049 (0)69-890 11-725
Fax   : +049 (0)69-890 11-749
E-Mail: ruediger.kupper at honda-ri.de
PGP ID: C2303358