flake8-class-attributes-order

An extension for flake8 to report on wrong class attributes order and class level logic.

The validator can extract class attribute type: docstring, property, nested class, GLOBAL_VAR, etc. If django model fields are detected, the validator can detect, if the field is link to another table (foreign key, generic key, etc) or not.

After resolving each attribute type, validator checks attributes order.

Here are methods order for non strict validation:

• __new__
• __init__
• __post_init__
• other magic methods
• @property
• @staticmethod
• @classmethod
• other methods
• private methods

And here are methods order if you have strict validation enabled:

• __new__
• __init__
• __post_init__
• other magic method
• @property
• @staticmethod
• @classmethod
• other methods
• private @property
• private @staticmethod
• private @classmethod
• other private methods

To enable strict validation, please set the flag in your config file:

use_class_attributes_order_strict_mode = True

If the order is broken, validator will report on it.

Besides methods, the validator checks other attributes methods: docstrings, nested classes, constants, attributes, and so on.

Also validator checks, if class has no class level logic and report if any. Here is an example:

class PhoneForm(forms.Form):
    phone = forms.CharField(17, label='Телефон'.upper())

    # this should happens in __init__!
    phone.widget.attrs.update({'class': 'form-control phone'})

Installation

pip install flake8-class-attributes-order

Example

DEBUG = True


class User:
    def fetch_info_from_crm(self):
        pass

    LOGIN_FIELD = 'email'  # wtf? this should be on top of class definition!


class UserNode:
    class Meta:
        model = User

    if DEBUG:  # not great idea at all
        def is_synced_with_crm(self):
            pass

Usage:

$ flake8 test.py
test.py:5:5: CCE001 User.fetch_info_from_crm should be after User.LOGIN_FIELD
test.py:15:5: CCE002 Class level expression detected model UserNode, line 15

Tested on Python 3.7.x and flake8 3.7.5.

Error codes

Error code	Description
CCE001	Wrong class attributes order (XXX should be after YYY)
CCE002	Class level expression detected

Contributing

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

• Create an issue with bug you found or proposal you have. Wait for approve from maintainer.
• Create a pull request. Make sure all checks are green.
• Fix review comments if any.
• 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. Sorry, styleguide is available only in Russian for now.
• We respect Django CoC. Make soft, not bullshit.