__future__ import checker, plugin for flake8

flake8, import, future
pip install flake8-future-import==0.4.7


__future__ import checker

Build Status Coverage Status Pypi Entry

A script to check for the imported __future__ modules to make it easier to have a consistent code base.

By default it requires and forbids all imports but it's possible to have certain imports optional by ignoring both their requiring and forbidding error code. In the future it's planned to have a “consistency” mode and that the default is having the import optional or required (not sure on that yet).

This module provides a plugin for flake8, the Python code checker.

Standalone script

The checker can be used directly:

$ python -m flake8-import --ignore FI10,FI11,FI12,FI13,FI15,FI5 some_file.py
some_file.py:1:1: FI14 __future__ import "unicode_literals" missing

Even though flake8 still uses optparse this script in standalone mode is using argparse.

Plugin for Flake8

When both flake8 and flake8-future-imports are installed, the plugin is available in flake8:

$ flake8 --version
5.0.3 (flake8-future-import: 0.4.6, mccabe: 0.7.0, pycodestyle: 2.9.0, pyflakes: 2.5.0) CPython 3.9.5 on Windows

By default the plugin will check for all the future imports but with --ignore it's possible to define which imports from __future__ are optional, required or forbidden. It will emit a warning if necessary imports are missing:

$ flake8 --ignore FI10,FI11,FI12,FI13,FI15,FI5 some_file.py
some_file.py:1:1: FI14 __future__ import "unicode_literals" missing


This module adds one parameter:

  • --require-code: Doesn't complain on files which only contain comments or strings (and by extension docstrings). Corresponds to require-code = True in the tox.ini.
  • --min-version: Define the minimum version supported by the project. Any features already mandatory or not available won't cause a warning when they are missing. Corresponds to min-version = … in the tox.ini.

The stand alone version also mimics flake8's ignore parameter.

Error codes

This plugin is using the following error codes:

FI10 __future__ import "division" missing
FI11 __future__ import "absolute_import" missing
FI12 __future__ import "with_statement" missing
FI13 __future__ import "print_function" missing
FI14 __future__ import "unicode_literals" missing
FI15 __future__ import "generator_stop" missing
FI16 __future__ import "nested_scopes" missing
FI17 __future__ import "generators" missing
FI18 __future__ import "annotations" missing
FI50 __future__ import "division" present
FI51 __future__ import "absolute_import" present
FI52 __future__ import "with_statement" present
FI53 __future__ import "print_function" present
FI54 __future__ import "unicode_literals" present
FI55 __future__ import "generator_stop" present
FI56 __future__ import "nested_scopes" present
FI57 __future__ import "generators" present
FI58 __future__ import "annotations" present
FI90 __future__ import does not exist

For a sensible usage, for each import either or both error code need to be ignored as it will otherwise always complain either because it's present or because it is not. The corresponding other error code can be determined by adding or subtracting 40.

  • Ignoring the lower one will forbid the import
  • Ignoring the higher one will require the import
  • Ignoring both will make the import optional

The plugin is always producing errors about missing and present imports and flake8 actually does ignore then the codes accordingly. So the plugin does not know that an import is allowed and forbidden at the same time and thus cannot skip reporting those imports.


0.4.7 - 2022-08-02

  • Fix error reported with flake8 version 5

0.4.6 - 2019-08-04

  • Add new annotations feature.

0.4.5 - 2018-04-15

  • Support pip version 10 in the tests.
  • Add LICENSE and test_flake8_future_import.py to the source distribution.

0.4.4 - 2018-01-05

  • Add Flake8 framework classifier.

0.4.3 - 2016-07-01

  • When using Flake8 version 2, it wasn't correctly looking for the options in the tox.ini file. This is restoring the old behaviour there.

0.4.2 - 2016-07-01

  • Support flake8 version 3's new config option interface
  • Do not increase offset by one in the standalone variant, like flake8 does with version 3

0.4.1 - 2016-05-30

  • Do not ignore imports which are present and have been added after the minimum version
  • Ignore imports which became mandatory with the minimum version

0.4.0 - 2016-05-30

  • Add two older future imports
  • Issue an error when a future import does not exist
  • Define which is the oldest Python version to be supported so that already mandatory features can be ignored and not yet supported features default to forbidden (ignoring the lower error code).
  • Use return code of 1 if errors occurred

0.3.2 - 2015-10-18

  • Prevent errors when using unknown future imports
  • Test several examples for bad future imports from the Python library
  • Fixed the README to use present for the higher codes

0.3.1 - 2015-09-07

  • Support setting --require-code in the tox.ini

0.3.0 - 2015-09-07

  • Using a different error code namespace (FIXX)
  • Add error codes returned when an import is present
  • Removed nested_scopes and generators from the available list
  • Skip files which only contains comments and strings

0.2.1 - 2015-08-10

  • Fixed the module and URL in setup.py
  • Fixed the name in the script itself

0.2 - 2015-08-10

  • Instead of parameters it's now using error codes to define which futures are missing. This is removing the ability to forbid a future for now.

0.1 - 2015-08-08

  • First release