Import order coding standard

Question

PEP8 suggests that:

Imports should be grouped in the following order:

1. standard library imports
2. related third party imports
3. local application/library specific imports

You should put a blank line between each group of imports.

Is there a way to check if the standard is violated anywhere in the package using static code analysis tools, like pylint, pyflakes, pychecker, pep8?

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Example of violation:

from my_package import my_module from django.db import models import os 

Correct way to import:

import os  from django.db import models  from my_package import my_module 

Answer 1

The current version of pylint now does this, and reports it as error class C0411.

Answer 2

Update (2016): sbywater has the most recent answer.

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Found it! (accidentally, while reading "Hacker's guide to python")

OpenStack Hacking Style Checks project named hacking introduces several unique flake8 extensions. There is hacking_import_groups among them (related commit).

Example:

• requirements

  • tox
  • flake8

  • hacking (from the master branch):

    $ git clone https://github.com/openstack-dev/hacking.git $ cd hacking/ $ python setup.py install 

• files used in the example

  • tox.ini (we need to tell flake8 that we want to use a custom check)

    [hacking] local-check = hacking.core.hacking_import_groups 

    UPD: with the newest version of hacking the path to the check changed, now it is hacking.checks.imports.hacking_import_groups.

  • test.py (target of the check)

    import requests import sys from my_module import print_smth   print_smth(requests.get('https://google.com')) print_smth(sys.version) 

  • my_module.py (local import used by test.py)

    def print_smth(smth):     print smth 

Then, if I run flake8 against test.py:

$ flake8 test.py test.py:2:1: H305  imports not grouped correctly (requests: third-party, sys: stdlib) test.py:3:1: H305  imports not grouped correctly (sys: stdlib, my_module.print_smth: project) test.py:3:1: H306  imports not in alphabetical order (sys, my_module.print_smth) 

Then, if I group the imports in the correct order following PEP8:

import sys  import requests  from my_module import print_smth   print_smth(requests.get('https://google.com')) print_smth(sys.version) 

No warnings found:

$ flake8 test.py $ 

Hope this will help somebody in the future.