python import fails even if __init__.py is present

Question

suppose i have this directory structure

package /
 __init__.py
 cpackage.py
 subpackage1/
 __init__.py
 subpack1_call.py
 /lib
 __init__.py
 sub_lib.py
 subpackage2/
 __init__.py
 subpack2_call.py

i want to import cpackage in subpackage1 and subpackage2 which i am unable to import i get valuename error and module not found errors

where as i can easily do this in subpackage1

from lib.sub_lib import hello_pr
hello_pr() 

here there is no error and hello_pr prints what i defined in sub_lib but i am unable to move up the directory, where as in above case i can easily move down the directory structure

what am i missing . i have looked into so many solutions in this site and pydoc, maybe i am missing something, cause nothing seemed to be working for

Answer 1

If you can import lib.sub_lib, it means your PYTHONPATH points to subpackage1. It should point to the directory containing package, then you'll be able to import package.cpackage, package.subpackage1.lib.sub_lib, etc.

You can also point your PYTHONPATH to cpackage, then remove init.py in this directory as it's useless, and you can import cpackage, subpackage1.lib.sub_lib, etc.

The basic rule is: if PYTHONPATH=dir, then

dir\
 bob.py
 sub\
 __init__.py
 bib.py
 inner\
 __init__.py
 bub.py
import bob
import sub (will import sub\__init__.py)
import sub.bib (will import sub\__init__.py then bib.py)
import sub.inner (will import sub\__init__.py then sub\inner\__init__.py)
import sub.inner.bub (will import sub\__init__.py then sub\inner\__init__.py
 and finally bub.py)

• rgm: if set the pythonpath and then do py2exe of my project, will it cause any execution error in some other computer. ( forgive me my question is highly ridiculous)
• user1220978: When you build your application, py2exe finds all needed packages, even those which are accessed in PYTHONPATH, and they are packed in library.zip. However, the distributed exe file doesn't depend on PYTHONPATH (it won't look at it, to prevent problems if installed libraries conflict with your program).
• rgm: so the packages will be in library.zip and distributed exe will look in library.zip. right? i dont have to change os.sys?
• user1220978: No, you don't have to change sys.path (at least for "simple" programs).
• user1220978: You mean you have PYTHONPATH=...\dir and you import sub.bib ? Well... I'm afraid I'm a bit confused too ;-) Anyway, I think it should work with py2exe, given it works with python. I must be missing something...

Answer 2

After parsing and reparsing your question a few times, I've decided that what you're looking for is relative imports.

from ..cpackage import somename

• rgm: this the error which i am seeing : File "subpackage1.py", line 1, in <module> from ..cpackage import callsome_one ValueError: Attempted relative import in non-packag
• user1220978: You may have a look at stackoverflow.com/questions/5803781/… and stackoverflow.com/questions/72852/… and also py2exe.org/index.cgi/FAQ