Use classproperty to access field attributes of a class (#78180)

* Use classproperty to access field attributes of a class, consolidate into one class

changelogs/fragments/fieldattributes-classproperty.yml

@@ -0,0 +1,2 @@
+minor_changes:
+  - Utilize @classmethod and @property together to form classproperty (Python 3.9) to access field attributes of a class

lib/ansible/playbook/base.py

@@ -69,9 +69,9 @@ def _validate_action_group_metadata(action, found_group_metadata, fq_group_name)
         display.warning(" ".join(metadata_warnings))
 
 
-# FIXME use @property and @classmethod together which is possible since Python 3.9
-class _FABMeta(type):
+class FieldAttributeBase:
 
+    @classmethod
     @property
     def fattributes(cls):
         # FIXME is this worth caching?
@@ -86,14 +86,6 @@ class _FABMeta(type):
                     fattributes[attr.alias] = attr
         return fattributes
 
-
-class FieldAttributeBase(metaclass=_FABMeta):
-
-    # FIXME use @property and @classmethod together which is possible since Python 3.9
-    @property
-    def fattributes(self):
-        return self.__class__.fattributes
-
     def __init__(self):
 
         # initialize the data loader and variable manager, which will be provided

test/units/playbook/test_base.py

@@ -488,7 +488,7 @@ class TestBaseSubClass(TestBase):
     def test_attr_class_post_validate_class_not_instance(self):
         not_a_esc = ExampleSubClass
         ds = {'test_attr_class_post_validate': not_a_esc}
-        self.assertRaisesRegex(AnsibleParserError, 'is not a valid.*got a.*Meta.*instead',
+        self.assertRaisesRegex(AnsibleParserError, "is not a valid.*got a <class 'type'> instead",
                                self._base_validate, ds)
 
     def test_attr_class_post_validate_wrong_class(self):