Better inference of class and static methods decorated with custom me…

…thods

Close pylint-dev/pylint#3209

ChangeLog

@@ -14,6 +14,10 @@ Release Date: TBA
 
  Close PyCQA/pylint#3414
 
+* Better inference of class and static methods decorated with custom methods
+
+ Close PyCQA/pylint#3209
+
 * Numpy `datetime64.astype` return value is inferred as a `ndarray`.
 
  Close PyCQA/pylint#3332

astroid/scoped_nodes.py

@@ -1076,6 +1076,21 @@ def _infer_decorator_callchain(node):
  return "classmethod"
  if result.is_subtype_of("%s.staticmethod" % BUILTINS):
  return "staticmethod"
+ if isinstance(result, FunctionDef):
+ if not result.decorators:
+ return None
+ # Determine if this function is decorated with one of the builtin descriptors we want.
+ for decorator in result.decorators.nodes:
+ if isinstance(decorator, node_classes.Name):
+ if decorator.name in BUILTIN_DESCRIPTORS:
+ return decorator.name
+ if (
+ isinstance(decorator, node_classes.Attribute)
+ and isinstance(decorator.expr, node_classes.Name)
+ and decorator.expr.name == BUILTINS
+ and decorator.attrname in BUILTIN_DESCRIPTORS
+ ):
+ return decorator.attrname
  return None
 
 

tests/unittest_inference.py

@@ -5566,5 +5566,83 @@ def test_infer_dict_passes_context():
  assert inferred.qname() == "builtins.dict"
 
 
+@pytest.mark.parametrize(
+ "code,obj,obj_type",
+ [
+ (
+ """
+ def klassmethod1(method):
+ @classmethod
+ def inner(cls):
+ return method(cls)
+ return inner
+
+ class X(object):
+ @klassmethod1
+ def x(cls):
+ return 'X'
+ X.x
+ """,
+ BoundMethod,
+ "classmethod",
+ ),
+ (
+ """
+ def staticmethod1(method):
+ @staticmethod
+ def inner(cls):
+ return method(cls)
+ return inner
+
+ class X(object):
+ @staticmethod1
+ def x(cls):
+ return 'X'
+ X.x
+ """,
+ nodes.FunctionDef,
+ "staticmethod",
+ ),
+ (
+ """
+ def klassmethod1(method):
+ def inner(cls):
+ return method(cls)
+ return classmethod(inner)
+
+ class X(object):
+ @klassmethod1
+ def x(cls):
+ return 'X'
+ X.x
+ """,
+ BoundMethod,
+ "classmethod",
+ ),
+ (
+ """
+ def staticmethod1(method):
+ def inner(cls):
+ return method(cls)
+ return staticmethod(inner)
+
+ class X(object):
+ @staticmethod1
+ def x(cls):
+ return 'X'
+ X.x
+ """,
+ nodes.FunctionDef,
+ "staticmethod",
+ ),
+ ],
+)
+def test_custom_decorators_for_classmethod_and_staticmethods(code, obj, obj_type):
+ node = extract_node(code)
+ inferred = next(node.infer())
+ assert isinstance(inferred, obj)
+ assert inferred.type == obj_type
+
+
 if __name__ == "__main__":
  unittest.main()