Warn against importing symbols starting with underscore

[hlovatt]

Hi All,

I'm new to Ruff and was therefore hoping someone more skilled might help. I have scoured the docs and stack overflow, but no luck.

I want a rule that Warns against importing symbols starting with underscore, is there one?

EG in ex.py:

def _ex(): ...

in use.py:

from ex import _ex

and I want a warning to say I shouldn't import _ex because it is 'private'.

Does anything like this exist?

Thanks,

Howard.

[MichaReiser]

plc2701 might be what you're looking for but it's a preview only rule for now (see preview mode)

[hlovatt]

Tried ruff check --preview --select PLC2701 on a codebase that should have failed, but it didn't :(.

Do I need a dev version of ruff or something? Is my command correct?

[MichaReiser]

The command looks correctly. Can you share a code example where it isn't working for you? Also note the Known problems section

[hlovatt]

OK simple cases work for me - will investigate and get back - thanks.

[hlovatt]

I'm using Beware that uses an unusual project structure, which I'm assuming is the problem. I've recreated a simpler version of the project structure that shows the problem:

__init__.py is empty, ex.py is:

def _ex():
    print('called')

and use.py is:

from ruffissue.ex import _ex

_ex()

ruff check --preview --select PLC2701 doesn't find the issue when run from any of the directories: ~repos/ruffissue, ~repos/ruffissue/src, or ~repos/ruffissue/src/ruffissue.

Any idea what the problem is?

[MichaReiser]

Thanks for the repro.

The rule allows private imports from within the same module where the module is ruffissue. You can see this by moving use.py outside of the ruffissue directory and PLC2701 then flags the improt of _ex.

[hlovatt]

Thanks. I was wanting underscored names to be private to the file. I guess you can't cover every possible interpretation of underscored names.