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A flake8 extension that checks classes attributes order

Project description

flake8-class-attributes-order

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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.

Default configuration checks for the following order of attributes:

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

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 happen in __init__!
    phone.widget.attrs.update({'class': 'form-control phone'})

Installation

pip install flake8-class-attributes-order

Configuration

Strict mode

There is another preconfigured order that is more strict on private subtypes:

  • __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:

[flake8]
use_class_attributes_order_strict_mode = True

Manual order configuration

Order can be manually configured via class_attributes_order config setting.

For example, if you prefer to put class Meta after constants and fields:

[flake8]
class_attributes_order =
    field,
    meta_class,
    nested_class,
    magic_method,
    property_method,
    static_method,
    class_method,
    method,
    private_method

Configurable options:

Option Description Fallbacks to*
meta_class class Meta: (e.g. in Django projects) nested_class
nested_class Other nested classes None*
constant SOME_CONSTANTS field
outer_field some = models.ForeignKey etc. field
field Other fields None
__new__ __new__ magic_method
__init__ __init__ magic_method
__post_init__ __post_init__ magic_method
__str__ __str__ magic_method
magic_method Other magic methods method
save def save(...) method
delete def delete(...) method
property_method @property/@cached_property etc. method
private_property_method @property/@cached_property with _ property_method
static_method @staticmethod method
private_static_method @staticmethod beginning with _ static_method
class_method @classmethod method
private_class_method @classmethod beginning with _ class_method
private_method other methods beginning with _ method
method other methods None

* if not provided, will use its supertype order

** if not defined, such base types and all their subtypes (unless defined) will be ignored during validation. It's recommended to set at least nested_class, field and method

You choose how detailed your configuration is. For example, you can define order of each supported magic method (__new__, __str__, etc.), or set magic_method to allow any order among them or even just use method

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:

Project details


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