Remove caching layer

pylint/checkers/design_analysis.py

@@ -23,10 +23,9 @@
 
 """check for signs of poor design"""
 
-import functools
 import re
 from collections import defaultdict
-from typing import List, Set, Tuple, cast
+from typing import FrozenSet, List, Set, cast
 
 import astroid
 from astroid import nodes
@@ -240,7 +239,7 @@ def _count_methods_in_class(node):
 
 
 def _get_parents(
-    node: nodes.ClassDef, ignored_parents: Set[str]
+    node: nodes.ClassDef, ignored_parents: FrozenSet[str]
 ) -> Set[nodes.ClassDef]:
     r"""Get parents of ``node``, excluding ancestors of ``ignored_parents``.
 
@@ -268,20 +267,6 @@ def _get_parents(
     return parents
 
 
-@functools.lru_cache(maxsize=32)
-def _combine_tuples_to_set(
-    tuple_1: Tuple[str, ...], tuple_2: Tuple[str, ...]
-) -> Set[str]:
-    """Combine two tuples into a set.
-
-    This is cached to avoid constructing a set for every call of
-    :any:`MisdesignChecker.visit_classdef`.
-    """
-    ret = set(tuple_1)
-    ret.update(tuple_2)
-    return ret
-
-
 class MisdesignChecker(BaseChecker):
     """checks for sign of poor/misdesign:
     * number of methods, attributes, local variables...
@@ -434,10 +419,7 @@ def _ignored_argument_names(self):
     def visit_classdef(self, node: nodes.ClassDef):
         """check size of inheritance hierarchy and number of instance attributes"""
         parents = _get_parents(
-            node,
-            _combine_tuples_to_set(
-                STDLIB_CLASSES_IGNORE_ANCESTOR, self.config.ignored_parents
-            ),
+            node, STDLIB_CLASSES_IGNORE_ANCESTOR.union(self.config.ignored_parents)
         )
         print(parents)
         nb_parents = len(parents)