Need instructions about pylint/pychecker setup

[patrakov]

Any attempt to run pylint or pychecker on anything that uses any Flask extension, e.g.:

from flask.ext.login import user_logged_in, user_logged_out

produces errors like the following:

F:  5,0: Unable to import 'flask.ext.login'
E:  5,0: No name 'login' in module 'flask.ext'

Some documentation is needed how to coerce pylint and pychecker into understanding how flask.ext.login is imported.

[hellysmile]

thats looks that you are using virtualenv, but your pylint\pychecker\pep8\pyflakes\flake8 installed at system globally

[patrakov]

No virtualenv is used here. All of flask, flask-login, pylint, pychecker and pyflakes are installed system-wide. Pylint is started as follows:

PYTHONPATH=. pylint cabinet

i.e. the modules related to "cabinet" are not installed system-wide, but they import flask-related modules from the global installation. And they work when imported from the command line or from a script.

[ghost]

Well, actually, module flask.ext.login does not exists: it's just a "shortcut" to module flask_login, implemented with sys.meta_path (check out Python docs and Flask implementation).

PS @patrakov: that's the output of Pylint or Pychecker?

[patrakov]

This is the minimal test file demonstrating the problem (save as cabinet.py):

from flask import Flask
from flask.ext.login import user_logged_in, user_logged_out
from flask.ext.babel import Babel

def create_app():
    app = Flask(__name__)
    babel = Babel(app)
    return app

This is the beginning of the output from pylint:

No config file found, using default configuration
************* Module cabinet
C:  1,0: Missing docstring
F:  2,0: Unable to import 'flask.ext.login'
E:  2,0: No name 'login' in module 'flask.ext'
F:  3,0: Unable to import 'flask.ext.babel'
E:  3,0: No name 'babel' in module 'flask.ext'
C:  5,0:create_app: Missing docstring
W:  7,4:create_app: Unused variable 'babel'
W:  2,0: Unused import user_logged_out
W:  2,0: Unused import user_logged_in

This is the output from pychecker:

Processing module cabinet (cabinet)...
  Caught exception importing module cabinet:
    File "/usr/lib64/python2.7/site-packages/pychecker/pcmodules.py", line 540, in setupMainCode()
      module = imp.load_module(self.moduleName, handle, filename, smt)
    File "cabinet.py", line 3, in <module>()
      from flask.ext.babel import Babel
    File "/usr/lib64/python2.7/site-packages/flask/exthook.py", line 61, in load_module()
      __import__(realname)
    File "/usr/lib64/python2.7/site-packages/flaskext/babel.py", line 21, in <module>()
      from babel import dates, numbers, support, Locale
    File "/usr/lib64/python2.7/site-packages/babel/__init__.py", line 33, in <module>()
      from pkg_resources import get_distribution, ResolutionError
    File "/usr/lib64/python2.7/site-packages/pkg_resources.py", line 2793, in <module>()
      _declare_state('object', working_set = WorkingSet())
    File "/usr/lib64/python2.7/site-packages/pkg_resources.py", line 442, in __init__()
      self.add_entry(entry)
    File "/usr/lib64/python2.7/site-packages/pkg_resources.py", line 457, in add_entry()
      for dist in find_distributions(entry, True):
    File "/usr/lib64/python2.7/site-packages/pkg_resources.py", line 1704, in find_distributions()
      importer = get_importer(path_item)
    File "/usr/lib64/python2.7/pkgutil.py", line 384, in get_importer()
      importer = path_hook(path_item)
  TypeError: must be string, not None

Warnings...

cabinet:1: NOT PROCESSED UNABLE TO IMPORT

[malicustommade]

I hit this too. There is this:

http://engineering.pave.com/post/51820567994/welcome-linting-flask-ext

[mitsuhiko]

I think this should be covered elsewhere. Just for the record: flask.ext.foo does not have to be used, you can use flask_foo with new extensions and flaskext.foo with old ones. The flask.ext module mainly exists so that transitions for users is less painful.