flake8-expression-complexity

An extension for flake8 that validates expression complexity.

Splits code into expression and scores each according to how much one is complicated. Fires an error on each expression more complex than theshold.

Default complexity is 7, can be configured via --max-expression-complexity option.

Since Django ORM queries can produce long and readable expressions, checker can skip them. To enable this behaviour, use --ignore-django-orm-queries-complexity option.

Installation

pip install flake8-expression-complexity

Example

if (
    (user and user.is_authorized)
    and user.subscriptions.filter(start_date__lt=today, end_date__gt=today).exists()
    and (
        user.total_credits_added
        - Check.objects.filter(user=user).aggregate(Sum('price'))['check__sum']
    )
    and UserAction.objects.filter(user=user).last().datetime > today - datetime.timedelta(days=10)
):
    ...

Usage:

$ flake8 --max-expression-complexity=3 test.py
text.py:2:5: ECE001 Expression is too complex (7.0 > 3)

Error codes

Error code	Description
ECE001	Expression is too complex (X > Y)

Contributing

We would love you to contribute to our project. It's simple:

1. Create an issue with bug you found or proposal you have. Wait for approve from maintainer.
2. Create a pull request. Make sure all checks are green.
3. Fix review comments if any.
4. Be awesome.

Here are useful tips:

• You can run all checks and tests with make check. Please do it before TravisCI does.
• We use BestDoctor python styleguide.
• We respect Django CoC. Make soft, not bullshit.