Let’s say I have the following structure:

my_module/
  __init__.py
  utilities.py

and __init__.py contains

from .utilities import SomeUtilityFunction

Is there a way to prevent or alert developers when they do

from my_module.utilities import SomeUtilityFunction

instead of

from my_module import SomeUtilityFunction

The problem arose when a few modules started using a function that was imported inside a module in which it wasn’t used, while also being available on the module’s __init__.py, so after linting the file and removing the unused import my tests started failing.

any other advice for situations like this?

  • Chais@sh.itjust.worksEnglish
    3·
    1 year ago

    You could guard it.
    __init__.py:

    _GUARD_SOME_UTILITY_FUNCTION = True
from .utilities import SomeUtilityFunction

    utilities.py:

    def SomeUtilityFunction():
    if not _GUARD_SOME_UTILITY_FUNCTION:
        raise SomeException("Helpful error message")

    Take this with a grain of salt, as I’m typing this on my phone and haven’t actually tried it.

    Alternatively there’s the import-guard package on PyPI. No idea if it’s any good, though. Just something a quick search brought up.

    Edit:
    Ok, I tried my suggestion and it doesn’t work.

    • sebsch
      2·
      1 year ago

      This approach seems quite overkomplex. Instead of having these errors on runtime, stuff like this should sit in linter rules of any kind.

    • Chais@sh.itjust.works
      21·
      1 year ago

      That’s not correct. __all__ is not a whitelist. It is only the list used for

      from module import *

      If you have a module with submodules foo, bar and baz and __all__ = ["foo", "bar"] it will not prevent you from importing baz manually. It just won’t do it automatically.

      • sebsch
        11·
        1 year ago

        It works exactly like one. You get a warning if you try to import something not defined in it. The docs are just very confusing here ;)

        • Chais@sh.itjust.worksEnglish
          11·
          1 year ago

          Bullshit!

          module/__init__.py:

          __all__ = ["foo", "bar"]

          module/foo.py:

          def foo():
    print("foo")

          module/bar.py:

          def bar():
    print("bar")

          module/baz.py:

          def baz():
    print("baz")

          main.py:

          from module import *
from module import baz

if __name__ == "__main__":
    print("main")
    foo.foo()
    bar.bar()
    baz.baz()

          Output:

          $ python main.py 
main
foo
bar
baz

          No errors, warnings or anything.