Organising packages/modules - importing functions from a common.py in a separate directory?
Peter Otten
__peter__ at web.de
Tue Oct 29 03:44:47 EDT 2013
Victor Hooi wrote:
> Hi,
>
> Hmm, this post on SO seems to suggest that importing from another sibling
> directory in a package ins't actually possibly in Python without some ugly
> hacks?
>
> http://stackoverflow.com/questions/6323860/sibling-package-imports
>
> Did I read the above correctly?
Yes.
> Is there another way I can structure my code so that I can run the
> sync_em.py and sync_pg.py scripts, and they can pull common functions from
> somewhere?
The packages you are trying to access in your original post
> foo_loading/
> __init__.py
> common/
> common_foo.py
> em_load/
> __init__.py
> config.yaml
> sync_em.py
> pg_load/
> __init__.py
> config.yaml
> sync_pg.py
aren't actually siblings in the sense of the stackoverflow topic above, they
are subpackages of foo_loading, and as you already found out
> So from within the sync_em.py script, I'm trying to import a function from
foo_loading/common/common_foo.py.
>
> from ..common.common_foo import setup_foo_logging
>
> I get the error:
>
> ValueError: Attempted relative import in non-package
>
> If I change directories to the parent of "foo_loading", then run
>
> python -m foo_loading.em_load.sync_em sync_em.py
>
> it works. However, this seems a bit roundabout, and I suspect I'm not
doing things correctly.
>
> Ideally, I want a user to be able to just run sync_em.py from it's own
directory, and have it correctly import the logging/config modules from
common_foo.py, and just work.
>
> What is the correct way to achieve this?
you can access them as long as the *parent* directory of foo_loading is in
sys.path through PYTHONPATH, or as the working directory, or any other
means. However, if you step into the package, e. g.
$ cd foo_loading
$ python -c 'import common'
then from Python's point of view 'common' is a toplevel package rather than
the intended 'foo_loading.common', and intra-package imports will break.
To preserve your sanity I therefore recommend that you
(1) avoid to put package directories into sys.path
(1a) avoid to cd into a package
(2) put scripts you plan to invoke directly rather than import outside the
package.
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