flake8-future-import 0.4.2

__future__ import checker, plugin for flake8

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

$ flake8 --version
2.0 (pep8: 1.4.2, flake8-future-imports: 0.4.2, pyflakes: 0.6.1)

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

Parameters

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
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
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 substracting 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.

Changes

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