flake8-return

Flake8 plugin that checks return values.

Installation

pip install flake8-return

Errors

• R501 do not explicitly return None in function if it is the only possible return value.

def x(y):
    if not y:
        return
    return None  # error!

• R502 do not implicitly return None in function able to return non-None value.

def x(y):
    if not y:
        return  # error!
    return 1

• R503 missing explicit return at the end of function able to return non-None value.

def x(y):
    if not y:
        return 1
    # error!

• R504 unnecessary variable assignment before return statement.

def x():
    a = 1
    # some code that not using `a`
    print('test')
    return a  # error!

• R505 unnecessary else after return statement.

def x(y, z):
    if y:  # error!
        return 1
    else:
        return z

• R506 unnecessary else after raise statement.

def x(y, z):
    if y:  # error!
        raise Exception(y)
    else:
        raise Exception(z)

• R507 unnecessary else after continue statement.

def x(y, z):
    for i in y:
        if i < z:  # error!
            continue
        else:
            a = 0

• R508 unnecessary else after break statement.

def x(y, z):
    for i in y:
        if i > z:  # error!
            break
        else:
            a = 0

Returns in asyncio coroutines also supported.

For developers

Show help

make help

Create venv and install deps

make init

Install git precommit hook

make precommit

Run linters, autoformat, tests etc

make pretty lint test

Bump new version

make bump_major
make bump_minor
make bump_patch

Change Log

Unreleased

• ...

1.2.0 - 2022-10-28

• Port no-else-break, no-else-continue, no-else-raise, no-else-return from pylint (#122) Calum Young
• PEP 621: Migrate more config to pyproject.toml (#123) Christian Clauss
• Fix/116/R504-try-except (#120) Calum Young
• Update ci (#119) Calum Young
• Fix/47/Update-R504-for-assignment-value (#117) Calum Young
• Upgrade GitHub Actions (#113) Christian Clauss
• Add a space to avoid a typo in R503 (#98) Christian Clauss
• GitHub Action to lint Python code (#97) Christian Clauss
• Typo fixes (#92) Aarni Koskela
• Create codeql-analysis.yml Afonasev Evgeniy
• Bump flake8-plugin-utils from 1.1.1 to 1.3.2 (#87) dependabot
• Bump mypy from 0.812 to 0.971 (#114) dependabot
• Bump pytest-cov from 3.0.0 to 4.0.0 (#124) dependabot
• Bump pytest-cov from 2.11.1 to 3.0.0 (#102) dependabot
• Bump pytest-mock from 3.6.0 to 3.6.1 (#91) dependabot
• Bump pytest from 6.2.4 to 6.2.5 (#99) dependabot
• Bump pylint from 2.8.2 to 2.10.2 (#100) dependabot
• Bump pytest from 6.2.3 to 6.2.4 (#86) dependabot

1.1.3 - 2021-05-05

• Error clarifications (#77) Clément Robert
• fix linting (migrate to black 20.0b1) (#78) Clément Robert

1.1.2 - 2020-07-09

• Make R504 visitors handle while loops (#56) Frank Tackitt
• Rename allows-prereleases to allow-prereleases (#55) Frank Tackitt
• Fix typo: → haven't (#24) Jon Dufresne

1.1.1 - 2019-09-21

• fixed #3 The R504 doesn't detect that the variable is modified in loop
• fixed #4 False positive with R503 inside async with clause

1.1.0 - 2019-05-23

• update flask_plugin_utils version to 1.0

1.0.0 - 2019-05-13

• skip assign after unpacking while unnecessary assign checking "(x, y = my_obj)"

0.3.2 - 2019-04-01

• allow "assert False" as last function return

0.3.1 - 2019-03-11

• add pypi deploy into travis config
• add make bump_version command

0.3.0 - 2019-02-26

• skip functions that consist only return None
• fix false positive when last return inner with statement
• add unnecessary assign error
• add support tuple in assign or return expressions
• add support asyncio coroutines

0.2.0 - 2019-02-21

• fix explicit/implicit
• add flake8-plugin-utils as dependency
• allow raise as last function return
• allow no return as last line in while block
• fix if/elif/else cases

0.1.1 - 2019-02-10

• fix error messages

0.1.0 - 2019-02-10

• initial