kiwi_lint/dunder_attributes.py

# Copyright (c) 2018,2023 Alexander Todorov <atodorov@MrSenko.com>

# Licensed under the GPL 2.0: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html

import astroid
from pylint import checkers
from pylint.checkers import utils


class DunderClassAttributeChecker(checkers.BaseChecker):
    name = "dunder-class-attribute-checker"

    msgs = {
        "C4401": (
            "Class attributes should not contain double underscores",
            "dunder-class-attribute",
            'Dunders, e.g. "__some_name__", are reserved for Python. '
            "Do not name your class attributes this way!",
        )
    }

    @utils.only_required_for_messages("dunder-class-attribute")
    def visit_classdef(self, node):
        """Detect when class attributes use double underscores."""
        # we can redefine special methods (e.g. __iter__) and some attributes,
        # e.g. __doc__, by declaring them as class attributes. Exclude them from the
        # test below.
        allowed_attributes = dir([])

        for child in node.body:
            if isinstance(child, astroid.Assign):
                for target in child.targets:
                    if (
                        isinstance(target, astroid.AssignName)
                        and target.name not in allowed_attributes
                        and target.name.startswith("__")
                        and target.name.endswith("__")
                    ):
                        self.add_message("dunder-class-attribute", node=child)