105 lines
3.8 KiB
Python
105 lines
3.8 KiB
Python
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# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
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# For details: https://github.com/pylint-dev/pylint/blob/main/LICENSE
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# Copyright (c) https://github.com/pylint-dev/pylint/blob/main/CONTRIBUTORS.txt
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from __future__ import annotations
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from typing import TYPE_CHECKING
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from astroid import Instance, nodes
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from astroid.util import UninferableBase
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from pylint.checkers import BaseChecker
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from pylint.checkers.utils import safe_infer
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from pylint.constants import DUNDER_METHODS, UNNECESSARY_DUNDER_CALL_LAMBDA_EXCEPTIONS
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from pylint.interfaces import HIGH
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if TYPE_CHECKING:
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from pylint.lint import PyLinter
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class DunderCallChecker(BaseChecker):
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"""Check for unnecessary dunder method calls.
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Docs: https://docs.python.org/3/reference/datamodel.html#basic-customization
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We exclude names in list pylint.constants.EXTRA_DUNDER_METHODS such as
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__index__ (see https://github.com/pylint-dev/pylint/issues/6795)
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since these either have no alternative method of being called or
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have a genuine use case for being called manually.
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Additionally, we exclude classes that are not instantiated since these
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might be used to access the dunder methods of a base class of an instance.
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We also exclude dunder method calls on super() since
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these can't be written in an alternative manner.
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"""
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name = "unnecessary-dunder-call"
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priority = -1
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msgs = {
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"C2801": (
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"Unnecessarily calls dunder method %s. %s.",
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"unnecessary-dunder-call",
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"Used when a dunder method is manually called instead "
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"of using the corresponding function/method/operator.",
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),
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}
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options = ()
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def open(self) -> None:
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self._dunder_methods: dict[str, str] = {}
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for since_vers, dunder_methods in DUNDER_METHODS.items():
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if since_vers <= self.linter.config.py_version:
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self._dunder_methods.update(dunder_methods)
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@staticmethod
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def within_dunder_or_lambda_def(node: nodes.NodeNG) -> bool:
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"""Check if dunder method call is within a dunder method definition."""
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parent = node.parent
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while parent is not None:
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if (
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isinstance(parent, nodes.FunctionDef)
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and parent.name.startswith("__")
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and parent.name.endswith("__")
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or DunderCallChecker.is_lambda_rule_exception(parent, node)
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):
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return True
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parent = parent.parent
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return False
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@staticmethod
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def is_lambda_rule_exception(ancestor: nodes.NodeNG, node: nodes.NodeNG) -> bool:
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return (
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isinstance(ancestor, nodes.Lambda)
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and node.func.attrname in UNNECESSARY_DUNDER_CALL_LAMBDA_EXCEPTIONS
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)
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def visit_call(self, node: nodes.Call) -> None:
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"""Check if method being called is an unnecessary dunder method."""
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if (
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isinstance(node.func, nodes.Attribute)
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and node.func.attrname in self._dunder_methods
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and not self.within_dunder_or_lambda_def(node)
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and not (
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isinstance(node.func.expr, nodes.Call)
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and isinstance(node.func.expr.func, nodes.Name)
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and node.func.expr.func.name == "super"
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)
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):
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inf_expr = safe_infer(node.func.expr)
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if not (
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inf_expr is None or isinstance(inf_expr, (Instance, UninferableBase))
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):
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# Skip dunder calls to non instantiated classes.
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return
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self.add_message(
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"unnecessary-dunder-call",
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node=node,
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args=(node.func.attrname, self._dunder_methods[node.func.attrname]),
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confidence=HIGH,
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)
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def register(linter: PyLinter) -> None:
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linter.register_checker(DunderCallChecker(linter))
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