Question

I am about at wits end with what should be an extremely simple issue. Here is the format of a simple example that I wrote to try to fix my problem. I have a folder top with __all__ = ["p1","p2"] in __init__.py . I then have sub-folders p1 and p2 with __init__.py in both of them with __all__ again defined with the names of two simple module quick1 and quick 2 with quick1 in p1 and quick2 in p2. If I import top.p1.quick1 from a script outside of top then the import works fine. However, trying to import top.p1.quick1 from quick2 gives the error
File "quick1.py", line 1, in <module>
import top.p2.quick2
ImportError: No module named top.p2.quick2

How can I import a module from another sub-package? This is supposed to work according to the python documentation as far as I can tell. Does anyone see an obvious, trivial mistake that I made?

Edit: It appears that I need to add the directory with top to my search path. I can do this temporarily by setting PYTHONPATH. However, is there a better way to do this from a distutils script?

Answer 1

All you describe is just fine and does not reproduce the error — here’s the simplest version I can think of:

$ mkdir /tmp/path
$ mkdir /tmp/path/top /tmp/path/top/p1 /tmp/path/top/p2
$ touch /tmp/path/top/__init__.py /tmp/path/top/p1/__init__.py /tmp/path/top/p2/__init__.py
$ touch /tmp/path/top/p1/quick1.py /tmp/path/top/p2/quick2.py$ echo 'import top.p1.quick1' > /tmp/path/top/p2/quick2.py
$ PYTHONPATH=/tmp/path python /tmp/path/top/p2/quick2.py
$ python -c 'import sys; sys.path.append("/tmp/path"); import top.p2.quick2'

and it runs just fine. The __all__ are not relevant unless you’re using from ... import * which you aren’t (and right you are not to). As long as the parent directory of top (here, /tmp/path) is on sys.path, things will be fine; if that parent directory is not there, you’ll get an error.

So what’s the minimal change you can make to this sequence of operations to reproduce the error you observe?