How to import two submodules in python with the same subfolder name

Question

My project structure looks like this:

project/
  main.py
  sub_a/
    class_a.py
    __init__.py
    utils/
      __init__.py
      util_a.py
  sub_b/
    class_b.py
    __init__.py
    utils/
      __init__.py
      util_b.py

And in each of class_a.py, class_b.py, there is an import like this:

from utils import util_a/b

My PYTHONPATH points to both sub_a and sub_b. When I try to

import class_b

in main.py, I get an ImportError:

ImportError: cannot import name util_b

I am using Python 2.7.

I understand that the error comes about because from utils import util_b is ambiguous, so Python chooses the first one on the path, but how can I rewrite the imports so that they work?

I don't think changing the PYTHONPATH is an option, since each of sub_a and sub_b assume they are part of the PYTHONPATH in their own internal imports. For instance, the from utils import util_b in class_b.py.

Where is the problematic import statement? Is it inside `main.py`? I started playing around with this in a repo: https://github.com/fireproofsocks/python_import . -- it's a work in progress but maybe one of the examples there will help clarify Python's behavior. — Everett, Jun 14 '19 at 22:46

ivan_pozdeev · Answer 1 · 2019-06-14T23:04:33.037

1

Don't add both subdirectories to PYTHONPATH. Instead, add only project to it and import sub_a.utils.util_a and sub_b.utils.utils_b.
(In the packages themselves, you can use relative imports to import things from the same subtree. E.g. in sub_b/__init__.py: import .utils.utils_b)

As per isinstance fails for a type imported via package and from the same module directly , if you add the subdirectories, utils package gets associated with whichever is earlier on sys.path and only it will be searched whenever you try to import anything from utils.

edited Jun 14 '19 at 23:04

answered Jun 14 '19 at 22:47

ivan_pozdeev

33,874
19
107
152

I don't think this quite works, since each submodule depends on its own imports. For instance, files in `sub_b` call something like `from utils import util_b`. – mwlon Jun 14 '19 at 22:52
1

@mwlon use relative imports in this case: `from .utils import util_b`. – ivan_pozdeev Jun 14 '19 at 23:00
So there's no way to make it work without changing one or both of the submodules? Also, aren't relative imports frowned upon? – mwlon Jun 14 '19 at 23:09
1

@mwlon A relative import is syntax sugar. `from .utils import util_b` in `sub_b` is equivalent to `from sub_b.utils import util_b` but without hardcoding the current module name. They may have been frowned upon when they were new but now they are supported by all non-EOL versions. See https://realpython.com/absolute-vs-relative-python-imports/ for pros and cons. – ivan_pozdeev Jun 14 '19 at 23:25

score 0 · Answer 2 · answered Jun 14 '19 at 22:48

0

What you looking for is 'Import As'

Good overview here: Answered in another thread from ... import OR import ... as for modules'

from project.sub_a import User as aUser

from project.sub_b import User as bUser

answered Jun 14 '19 at 22:48

Alex R

77
5

I clarified the constraint that each submodule requires its own pythonpath to import from utils, which becomes ambiguous. How do I work around that? – mwlon Jun 14 '19 at 23:00

How to import two submodules in python with the same subfolder name

2 Answers2