[ python-Bugs-1421513 ] IMPORT PROBLEM: Local submodule shadows global module

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Bugs item #1421513, was opened at 2006-02-01 15:48
Message generated for change (Comment added) made by birkenfeld
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Category: Python Interpreter Core
Group: None
>Status: Closed
>Resolution: Postponed
Priority: 5
Submitted By: Jens Engel (jens_engel)
Assigned to: Nobody/Anonymous (nobody)
Summary: IMPORT PROBLEM: Local submodule shadows global module

Initial Comment:
PYTHON: 2.3, 2.4
PLATFORMS: Solaris, Linux, Cygwin, Win32

Local sister modules seem to hide global ones (of the 
standard Python library) when import occurs in a 
submodule. This statement even holds for indirect 
imports from the standard Python library.


FILE STRUCTURE for EXAMPLES:
  - my/
      +-- __init__.py
      +-- main.py
      +-- main2.py
      +-- symbol.py
      \-- types.py

EXAMPLE 1: Local submodule shadows global one.
# -- file:my.main.py
# COMMAND-LINE: python my/main.py
# MY INTENTION: Import standard module "types".
import types  #< FAILURE: Imports my.types

if __name__ == "__main__":
    print types.StringTypes  #< EXCEPTION: StringTypes 
are not known.
# -- FILE-END


EXAMPLE 2: Indirect import uses "my.symbol" instead.
# -- file:my.main2.py
# COMMAND-LINE: python my/main2.py
# MY INTENTION: Import standard module "compiler".
# NOTE: Module "compiler" imports module "symbol"
import compiler  #< FAILURE: Imports my.symbol instead

if __name__ == "__main__":
    pass
# -- FILE-END
  
NOTE: Module import problems can be better checked 
with "python -v".

I have not found a work-around that let me decide if I 
want to import the global module or the local one. The 
only solution seens to be to relocate the module 
where "__main__" is used to another place where no 
such import conflict occurs.

If my analysis is correct, the "main" module provides 
another ROOT filesystem for Python libraries that is 
normally preferred over the PYTHONHOME filesystem.
If this is true, module names at this level must be 
UNIQUE in a GLOBAL namespace (that is only partly 
under my control) which I consider BAD.

NOTE: In C++ if have the "::" prefix to indicate that 
I want to use the global/default namespace (=module) 
and not a sub-namespace. I am not aware of such a idom 
in Python.


----------------------------------------------------------------------

>Comment By: Georg Brandl (birkenfeld)
Date: 2006-02-17 13:13

Message:
Logged In: YES 
user_id=1188172

This is, unfortunately, correct behavior. Python 2.5 will
hopefully fix this with new import semantics for relative
imports.

As a workaround, don't call your modules like global ones
when you need those.

----------------------------------------------------------------------

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https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1421513&group_id=5470