Fixes bug in deeper inheritance in configclass (#94)

# Description

This MR fixes the issue with multiple inheritances in the
`omni.isaac.orbit.utils.configclass` decorator. Earlier, if the
inheritance tree was more than one level deep and the lowest-level
configuration class was not updating its values from the middle-level
classes.

This was happening because in the middle-level classes, the default
values were being updated to dataclass fields and were not visible
anymore in the dictionary of the class itself. The configclass now
checks for their values in the `__dataclass_fields__` of the class as
well.

This was a regression in behavior but has been fixed now with a unit
test to capture deeper inheritance in configclass.

## Type of change

- Bug fix (non-breaking change which fixes an issue)

## Checklist

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./orbit.sh --format`
- [x] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file

source/extensions/omni.isaac.orbit/config/extension.toml

 [package]
 
 # Note: Semantic Versioning is used: https://semver.org/
-version = "0.7.2"
+version = "0.7.3"
 
 # Description
 title = "ORBIT framework for Robot Learning"

source/extensions/omni.isaac.orbit/docs/CHANGELOG.rst

 Changelog
 ---------
 
+0.7.3 (2023-07-25)
+~~~~~~~~~~~~~~~~~~
+
+Fixed
+^^^^^
+
+* Fixed the issue with multiple inheritance in the :class:`omni.isaac.orbit.utils.configclass` decorator.
+  Earlier, if the inheritance tree was more than one level deep and the lowest level configuration class was
+  not updating its values from the middle level classes.
+
 
 0.7.2 (2023-07-24)
 ~~~~~~~~~~~~~~~~~~

source/extensions/omni.isaac.orbit/omni/isaac/orbit/utils/configclass.py

@@ -260,9 +260,10 @@ def _process_mutable_types(cls):
                 class_members[key] = f
         # iterate over base class data fields
         # in previous call, things that became a dataclass field were removed from class members
+        # so we need to add them back here as a dataclass field directly
         for key, f in base.__dict__.get("__dataclass_fields__", {}).items():
             # store class member
-            if not isinstance(f, type) and key not in class_members:
+            if not isinstance(f, type):
                 class_members[key] = f
 
     # check that all annotations are present in class members

source/extensions/omni.isaac.orbit/test/test_configclass.py

@@ -8,7 +8,7 @@ import os
 import unittest
 from dataclasses import MISSING, asdict, field
 from functools import wraps
-from typing import ClassVar, List, Type
+from typing import Callable, ClassVar, List, Type
 
 from omni.isaac.orbit.utils.configclass import configclass
 from omni.isaac.orbit.utils.dict import class_to_dict, update_class_from_dict
@@ -143,14 +143,17 @@ class ParentDemoCfg:
     b = 2  # type annotation missing on purpose
     c: RobotDefaultStateCfg = MISSING  # add new missing field
     j: List[str] = MISSING  # add new missing field
+    func: Callable = MISSING  # add new missing field
 
 
 @configclass
 class ChildDemoCfg(ParentDemoCfg):
     """Dummy child configuration with missing fields."""
 
+    func = dummy_function1  # set default value for missing field
     c = RobotDefaultStateCfg()  # set default value for missing field
 
+    func_2: Callable = MISSING  # add new missing field
     d: int = MISSING  # add new missing field
     k: List[str] = ["c", "d"]
     e: ViewerCfg = MISSING  # add new missing field
@@ -158,6 +161,14 @@ class ChildDemoCfg(ParentDemoCfg):
     dummy_class = DummyClass
 
 
+@configclass
+class ChildChildDemoCfg(ChildDemoCfg):
+    """Dummy child configuration with missing fields."""
+
+    func_2 = dummy_function2
+    d = 2  # set default value for missing field
+
+
 """
 Configuration with class inside.
 """
@@ -529,6 +540,19 @@ class TestConfigClass(unittest.TestCase):
         # check variables
         cfg = ChildDemoCfg(a=20, d=3, e=ViewerCfg(), j=["c", "d"])
 
+        self.assertEqual(cfg.func, dummy_function1)
+        self.assertEqual(cfg.a, 20)
+        self.assertEqual(cfg.b, 2)
+        self.assertEqual(cfg.d, 3)
+        self.assertEqual(cfg.j, ["c", "d"])
+
+    def test_config_double_inheritance(self):
+        """Tests that inheritance works properly when inheriting twice."""
+        # check variables
+        cfg = ChildChildDemoCfg(a=20, d=3, e=ViewerCfg(), j=["c", "d"])
+
+        self.assertEqual(cfg.func, dummy_function1)
+        self.assertEqual(cfg.func_2, dummy_function2)
         self.assertEqual(cfg.a, 20)
         self.assertEqual(cfg.b, 2)
         self.assertEqual(cfg.d, 3)