Ale: pylint import problem with modules in the same folder

[apuignav]

I'm seeing a weird error being reported by pylint only running through ale.

As a MWE, I create in an empty folder two files, a.py and b.py and I import a in b.py, as shown in the screenshot.

As you can see, pylint complains that it cannot import a, but if I run it on the command line there is no problem:

[[temp shell]][22:53]/var/folders/d7/836zgpqn22q8v_tr90hvm9m40000gn/T/tmp.3195.2414.11604.10112$ pylint b.py
************* Module b
C:  3, 0: Final newline missing (missing-final-newline)
C:  1, 0: Missing module docstring (missing-docstring)

I was wondering if this is just me, or maybe it's picking the wrong pylint (I cannot configure the executable path...).

[w0rp]

It can't find module b because it doesn't know where the module is. We should possibly modify the command to include some directory in PYTHONPATH. The a.py text is being copied to a temporary file, and that temporary directory doesn't include b.py.

[apuignav]

To leave this here, I found a workaround modifying the init-hook of.pylintrc:

init-hook='import sys; sys.path.append(".")'

However, some general solution would be desirable, of course.

[w0rp]

The trick is in giving a good enough guess as to which directories to add to PYTHONPATH by default. Maybe the same directory the file is in and the top most directory with Python files in folders in it.

[bwells]

Using the VIRTUAL_ENV environment variable would handle 100% of my usecases. If this isn't present this would be handled by the system python path lookup anyway.

[apuignav]

I guess VIRTUAL_ENV is included already? If I understand properly, the problem is that the current directory (implicitly included in the PYTHONPATH) changes for the linting and therefore the correct path is not copied over.

[apuignav]

This is related to https://github.com/maralla/validator.vim/issues/56.

Basically it boils down to the fact that pylint expects to be run in the "correct" folder. I would say creating the tempfile in the same dir of the original file is the only solution, but it's very ugly...

[w0rp]

That causes other problems, like leaving temporary files behind and the filename not matching the original file.

[apuignav]

True... It's a hard problem.

On Thu, Dec 8, 2016 at 10:08 AM, w0rp [e-mail] wrote:

That causes other problems, like leaving temporary files behind and the
filename not matching the original file.

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--
Dr. Albert Puig Navarro
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[johnfraney]

Following up on @apuignav's workaround, instead of editing each .pylintrc, adding this to ale_python_pylint_options worked fairly well for me:

let g:ale_python_pylint_options = "--init-hook='import sys; sys.path.append(\".\")'"

It still didn't pick up the relative imports, but it is recognizing modules in the same directory.

[coldnight]

I have the same problem with relative imports

from . import mod
from ..pkg import mod2

It can't use PYTHONPATH to solve.

[w0rp]

Now the pylint linter will check files on disk instead, so you will have to open files or save them, and import paths will be understood for more projects. The version of pylint from virtualenv directories, as long as they live in some directory above the file you're editing, will be used instead, unless you turn that option off with g:ale_python_pylint_use_global.

[w0rp]

We might be able to check pylint files on the fly in the future if pylint get support for working with temporary files or input from stdin. See here: https://github.com/PyCQA/pylint/issues/1187

[exp]

@w0rp it seems pylint does now have support for stdin. I haven't checked it is sufficient for your needs though I'm afraid.