PyLint “Unable to import” error - how to set PYTHO

问题:

I'm running PyLint from inside Wing IDE on Windows. I have a sub-directory (package) in my project and inside the package I import a module from the top level, ie.

__init__.py
myapp.py
one.py
subdir\
    __init__.py
    two.py

Inside two.py I have import one and this works fine at runtime, because the top-level directory (from which myapp.py is run) is in the Python path. However, when I run PyLint on two.py it gives me an error:

F0401: Unable to import 'one'

How do I fix this?

回答1:

There are two options I'm aware of.

One, change the PYTHONPATH environment variable to include the directory above your module.

Alternatively, edit ~/.pylintrc to include the directory above your module, like this:

[MASTER]
init-hook='import sys; sys.path.append("/path/to/root")'

(Or in other version of pylint, the init-hook requires you to change [General] to [MASTER])

Both of these options ought to work.

Hope that helps.

回答2:

The solution to alter path in init-hook is good, but I dislike the fact that I had to add absolute path there, as result I can not share this pylintrc file among the developers of the project. This solution using relative path to pylintrc file works better for me:

[MASTER]
init-hook="from pylint.config import find_pylintrc; import os, sys; sys.path.append(os.path.dirname(find_pylintrc()))"

Note that pylint.config.PYLINTRC also exists and has the same value as find_pylintrc().

回答3:

1) sys.path is a list.

2) The problem is sometimes the sys.path is not your virtualenv.path and you want to use pylint in your virtualenv

3) So like said, use init-hook (pay attention in ' and " the parse of pylint is strict)

[Master]
init-hook='sys.path = ["/path/myapps/bin/", "/path/to/myapps/lib/python3.3/site-packages/", ... many paths here])'

or

[Master]
init-hook='sys.path = list(); sys.path.append("/path/to/foo")'

.. and

pylint --rcfile /path/to/pylintrc /path/to/module.py

回答4:

Do you have an empty __init__.py file in both directories to let python know that the dirs are modules?

The basic outline when you are not running from within the folder (ie maybe from pylint's, though I haven't used that) is:

topdir\
  __init__.py
  functions_etc.py
  subdir\
    __init__.py
    other_functions.py

This is how the python interpreter is aware of the module without reference to the current directory, so if pylint is running from its own absolute path it will be able to access functions_etc.py as topdir.functions_etc or topdir.subdir.other_functions, provided topdir is on the PYTHONPATH.

UPDATE: If the problem is not the __init__.py file, maybe just try copying or moving your module to c:\Python26\Lib\site-packages -- that is a common place to put additional packages, and will definitely be on your pythonpath. If you know how to do Windows symbolic links or the equivalent (I don't!), you could do that instead. There are many more options here: http://docs.python.org/install/index.html, including the option of appending sys.path with the user-level directory of your development code, but in practice I usually just symbolically link my local development dir to site-packages - copying it over has the same effect.

回答5:

I don't know how it works with WingIDE, but for using PyLint with Geany, I set my external command to:

PYTHONPATH=${PYTHONPATH}:$(dirname %d) pylint --output-format=parseable --reports=n "%f"

where %f is the filename, and %d is the path. Might be useful for someone :)

回答6:

I had to update the system PYTHONPATH variable to add my App Engine path. In my case I just had to edit my ~/.bashrc file and add the following line:

export PYTHONPATH=$PYTHONPATH:/path/to/google_appengine_folder

In fact, I tried setting the init-hook first but this did not resolve the issue consistently across my code base (not sure why). Once I added it to the system path (probably a good idea in general) my issues went away.

回答7:

One workaround that I only just discovered is to actually just run PyLint for the entire package, rather than a single file. Somehow, it manages to find imported module then.

回答8:

Try

if __name__ == '__main__':
    from [whatever the name of your package is] import one
else:
    import one

Note that in Python 3, the syntax for the part in the else clause would be

from .. import one

On second thought, this probably won't fix your specific problem. I misunderstood the question and thought that two.py was being run as the main module, but that is not the case. And considering the differences in the way Python 2.6 (without importing absolute_import from __future__) and Python 3.x handle imports, you wouldn't need to do this for Python 2.6 anyway, I don't think.

Still, if you do eventually switch to Python 3 and plan on using a module as both a package module and as a standalone script inside the package, it may be a good idea to keep something like

if __name__ == '__main__':
    from [whatever the name of your package is] import one   # assuming the package is in the current working directory or a subdirectory of PYTHONPATH
else:
    from .. import one

in mind.

EDIT: And now for a possible solution to your actual problem. Either run PyLint from the directory containing your one module (via the command line, perhaps), or put the following code somewhere when running PyLint:

import os

olddir = os.getcwd()
os.chdir([path_of_directory_containing_module_one])
import one
os.chdir(olddir)

Basically, as an alternative to fiddling with PYTHONPATH, just make sure the current working directory is the directory containing one.py when you do the import.

(Looking at Brian's answer, you could probably assign the previous code to init_hook, but if you're going to do that then you could simply do the appending to sys.path that he does, which is slightly more elegant than my solution.)

回答9:

The key is to add your project directory to sys.path without considering about the env variable.

For someone who use VSCode, here's a one-line solution for you if there's a base directory of your project:

[MASTER]
init-hook='base_dir="my_spider"; import sys,os,re; _re=re.search(r".+\/" + base_dir, os.getcwd()); project_dir = _re.group() if _re else os.path.join(os.getcwd(), base_dir); sys.path.append(project_dir)'

Let me explain it a little bit:

• re.search(r".+\/" + base_dir, os.getcwd()).group(): find base directory according to the editing file

• os.path.join(os.getcwd(), base_dir): add cwd to sys.path to meet command line environment

---

FYI, here's my .pylintrc:

https://gist.github.com/chuyik/f0ffc41a6948b6c87c7160151ffe8c2f

回答10:

I had this same issue and fixed it by installing pylint in my virtualenv and then adding a .pylintrc file to my project directory with the following in the file:

[Master]
init-hook='sys.path = list(); sys.path.append("./Lib/site-packages/")'

回答11:

Maybe by manually appending the dir inside the PYTHONPATH?

sys.path.append(dirname)

回答12:

I had the same problem and since i could not find a answer I hope this can help anyone with a similar problem.

I use flymake with epylint. Basically what i did was add a dired-mode-hook that check if the dired directory is a python package directory. If it is I add it to the PYTHONPATH. In my case I consider a directory to be a python package if it contains a file named "setup.py".

;;;;;;;;;;;;;;;;;
;; PYTHON PATH ;;
;;;;;;;;;;;;;;;;;

(defun python-expand-path ()
  "Append a directory to the PYTHONPATH."
  (interactive
   (let ((string (read-directory-name 
          "Python package directory: " 
          nil 
          'my-history)))
     (setenv "PYTHONPATH" (concat (expand-file-name string)
                  (getenv ":PYTHONPATH"))))))

(defun pythonpath-dired-mode-hook ()
  (let ((setup_py (concat default-directory "setup.py"))
    (directory (expand-file-name default-directory)))
    ;;   (if (file-exists-p setup_py)
    (if (is-python-package-directory directory)
    (let ((pythonpath (concat (getenv "PYTHONPATH") ":" 
                  (expand-file-name directory))))
      (setenv "PYTHONPATH" pythonpath)
      (message (concat "PYTHONPATH=" (getenv "PYTHONPATH")))))))

(defun is-python-package-directory (directory)
  (let ((setup_py (concat directory "setup.py")))
    (file-exists-p setup_py)))

(add-hook 'dired-mode-hook 'pythonpath-dired-mode-hook)

Hope this helps.

回答13:

In case anybody is looking for a way to run pylint as an external tool in PyCharm and have it work with their virtual environments (why I came to this question), here's how I solved it:

1. In PyCharm > Preferences > Tools > External Tools, Add or Edit an item for pylint.
2. In the Tool Settings of the Edit Tool dialog, set Program to use pylint from the python interpreter directory: $PyInterpreterDirectory$/pylint
3. Set your other parameters in the Parameters field, like: --rcfile=$ProjectFileDir$/pylintrc -r n $FileDir$
4. Set your working directory to $FileDir$

Now using pylint as an external tool will run pylint on whatever directory you have selected using a common config file and use whatever interpreter is configured for your project (which presumably is your virtualenv interpreter).

回答14:

The problem can be solved by configuring pylint path under venv: $ cat .vscode/settings.json

{
    "python.pythonPath": "venv/bin/python",
    "python.linting.pylintPath": "venv/bin/pylint"
}

回答15:

if you using vscode,make sure your package directory is out of the _pychache__ directory.

回答16:

Hello i was able to import the packages from different directory. I just did the following: Note: I am using VScode

Steps to Create a Python Package Working with Python packages is really simple. All you need to do is:

Create a directory and give it your package's name. Put your classes in it. Create a init.py file in the directory

For example: you have a folder called Framework where you are keeping all the custom classes there and your job is to just create a init.py file inside the folder named Framework.

And while importing you need to import in this fashion--->

from Framework import base

so the E0401 error disappears Framework is the folder where you just created init.py and base is your custom module which you are required to import into and work upon Hope it helps!!!!