On 09/03/2021 22:52, Cameron Simpson wrote:
On 09Mar2021 05:00, Larry Martell <larry.mart...@gmail.com> wrote:
Which is considered better? Having a long import path or setting PYTHONPATH?
For example, in a project where 50% of the imports come from the same top
level directory is it better to add that dir to the path or reference it in
the import statements?
All the below is personal opinion.
I'd be leaving the $PYTHONPATH alone - I tweak it to access the required
libraries, but not to change their dotted module paths.
For example, I include ~/lib/python in my personal environment to access
my personal modules, but I don't include
~/lib/python/cs/app/someapp/subpackage in order to shorten
"cs.app.someapp.subpackage.foo" to just "foo".
This is largely to avoid accidental shadowing of other modules. For
example, supposing "foo" above were the subpath "os.path". Yes,
contrived, but that's the flavour of problem I'm avoiding.
I think I'd be ok with it provided I didn't go too far down. Eg, if all
my "someapp"s were distinctively named I could be persuaded to use
~/lib/python/cs/app in the $PYTHONPATH, allowing
"someapp.subpackage.foo". But I'd still be reluctant.
If you have a bunch of different packages you want to think of as "top
level" but that live in different places for organizational reasons
(e.g. someapp in ~/lib/python/cs/app/someapp and thatlib in
~/lib/python/cs/lib/util/thatlib), I'd advocate treating them as proper
Python packages with their own setup.py and everything, and installing
them properly.
Editable installs (setup.py develop or pip install -e .) are great for this.
Personally when this is impractical for some reason I prefer creating
*.pth files in site-packages to messing with PYTHONPATH as I find this
easier to maintain, especially if you ever end up using different Python
versions or different virtual environments.
Just my 0.02 €.
If the project modules are tightly bound relative imports can get you a
fair way. Certainly within a package I do a lot of:
from .fixtures import these_things
to grab from the adjacent "fixtures.py" file instead of:
from project.submodule.fixtures import these_things
And I'm usually happy to go up an additional level:
from ..package2.fixtures import those_things
Somewhere around 3 dots I start to worry about presuming too much, but
that is an arbitrary decision based on the discipline (or lack of it) in
the project naming.
Cheers,
Cameron Simpson <c...@cskk.id.au>
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