Fixes configclass behavior to support user-defined post-init call (#114)

# Description

Previously, the configclass was overwriting a user-defined configclass
which isn't desirable. This MR adds a function to allow configclasses to
support
[`__post_init__`](https://docs.python.org/3/library/dataclasses.html#post-init-processing).

## 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`
- [ ] 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

---------
Co-authored-by: Nikita Rudin <nrudin@nvidia.com>
Co-authored-by: Mayank Mittal <mittalma@leggedrobotics.com>

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

 [package]
 
 # Note: Semantic Versioning is used: https://semver.org/
-version = "0.8.6"
+version = "0.8.7"
 
 # Description
 title = "ORBIT framework for Robot Learning"

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

 Changelog
 ---------
 
+0.8.7 (2023-08-03)
+~~~~~~~~~~~~~~~~~~
+
+Fixed
+^^^^^
+
+* Added support for `__post_init__ <https://docs.python.org/3/library/dataclasses.html#post-init-processing>`_ in
+  the :class:`omni.isaac.orbit.utils.configclass` decorator.
+
+
 0.8.6 (2023-08-03)
 ~~~~~~~~~~~~~~~~~~
 

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

@@ -74,7 +74,11 @@ def configclass(cls, **kwargs):
     # add field factory
     _process_mutable_types(cls)
     # copy mutable members
-    setattr(cls, "__post_init__", _custom_post_init)
+    # note: we check if user defined __post_init__ function exists and augment it with our own
+    if hasattr(cls, "__post_init__"):
+        setattr(cls, "__post_init__", _combined_function(cls.__post_init__, _custom_post_init))
+    else:
+        setattr(cls, "__post_init__", _custom_post_init)
     # add helper functions for dictionary conversion
     setattr(cls, "to_dict", _class_to_dict)
     setattr(cls, "from_dict", _update_class_from_dict)
@@ -316,6 +320,25 @@ def _custom_post_init(obj):
             setattr(obj, key, deepcopy(value))
 
 
+def _combined_function(f1: Callable, f2: Callable) -> Callable:
+    """Combine two functions into one.
+
+    Args:
+        f1 (Callable): The first function.
+        f2 (Callable): The second function.
+
+    Returns:
+        Callable: The combined function.
+    """
+
+    def _combined(*args, **kwargs):
+        # call both functions
+        f1(*args, **kwargs)
+        f2(*args, **kwargs)
+
+    return _combined
+
+
 """
 Helper functions
 """

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

@@ -100,6 +100,19 @@ class BasicDemoCfg:
     robot_default_state: RobotDefaultStateCfg = RobotDefaultStateCfg()
 
 
+@configclass
+class BasicDemoPostInitCfg:
+    """Dummy configuration class."""
+
+    device_id: int = 0
+    env: EnvCfg = EnvCfg()
+    robot_default_state: RobotDefaultStateCfg = RobotDefaultStateCfg()
+
+    def __post_init__(self):
+        self.device_id = 1
+        self.add_variable = 3
+
+
 """
 Dummy configuration to check type annotations ordering.
 """
@@ -143,6 +156,7 @@ class ParentDemoCfg:
     b = 2  # type annotation missing on purpose
     c: RobotDefaultStateCfg = MISSING  # add new missing field
     j: List[str] = MISSING  # add new missing field
+    i: List[str] = MISSING  # add new missing field
     func: Callable = MISSING  # add new missing field
 
 
@@ -160,6 +174,10 @@ class ChildDemoCfg(ParentDemoCfg):
 
     dummy_class = DummyClass
 
+    def __post_init__(self):
+        self.b = 3  # change value of existing field
+        self.i = ["a", "b"]  # change value of existing field
+
 
 @configclass
 class ChildChildDemoCfg(ChildDemoCfg):
@@ -168,6 +186,12 @@ class ChildChildDemoCfg(ChildDemoCfg):
     func_2 = dummy_function2
     d = 2  # set default value for missing field
 
+    def __post_init__(self):
+        """Post initialization function."""
+        super().__post_init__()
+        self.b = 4  # set default value for missing field
+        self.f = "new"  # add new missing field
+
 
 """
 Configuration with class inside.
@@ -211,6 +235,9 @@ class OutsideClassCfg:
     inside: InsideClassCfg = InsideClassCfg()
     x: int = 20
 
+    def __post_init__(self):
+        self.inside.b = "dummy_changed"
+
 
 """
 Dummy configuration: Functions
@@ -252,6 +279,18 @@ basic_demo_cfg_change_correct = {
     "device_id": 0,
 }
 
+basic_demo_post_init_cfg_correct = {
+    "env": {"num_envs": 56, "episode_length": 2000, "viewer": {"eye": [7.5, 7.5, 7.5], "lookat": [0.0, 0.0, 0.0]}},
+    "robot_default_state": {
+        "pos": (0.0, 0.0, 0.0),
+        "rot": (1.0, 0.0, 0.0, 0.0),
+        "dof_pos": (0.0, 0.0, 0.0, 0.0, 0.0, 0.0),
+        "dof_vel": [0.0, 0.0, 0.0, 0.0, 0.0, 1.0],
+    },
+    "device_id": 1,
+    "add_variable": 3,
+}
+
 """
 Test solutions: Functions
 """
@@ -356,6 +395,10 @@ class TestConfigClass(unittest.TestCase):
         cfg.from_dict(cfg_dict)
         self.assertDictEqual(cfg.to_dict(), basic_demo_cfg_change_correct)
 
+    def test_config_update_dict_using_post_init(self):
+        cfg = BasicDemoPostInitCfg()
+        self.assertDictEqual(cfg.to_dict(), basic_demo_post_init_cfg_correct)
+
     def test_invalid_update_key(self):
         """Test invalid key update."""
         cfg = BasicDemoCfg()
@@ -542,10 +585,13 @@ class TestConfigClass(unittest.TestCase):
 
         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"])
 
+        # check post init
+        self.assertEqual(cfg.b, 3)
+        self.assertEqual(cfg.i, ["a", "b"])
+
     def test_config_double_inheritance(self):
         """Tests that inheritance works properly when inheriting twice."""
         # check variables
@@ -554,10 +600,14 @@ class TestConfigClass(unittest.TestCase):
         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)
         self.assertEqual(cfg.j, ["c", "d"])
 
+        # check post init
+        self.assertEqual(cfg.b, 4)
+        self.assertEqual(cfg.f, "new")
+        self.assertEqual(cfg.i, ["a", "b"])
+
     def test_config_with_class_type(self):
         """Tests that configclass works properly with class type."""
 
@@ -587,7 +637,7 @@ class TestConfigClass(unittest.TestCase):
         self.assertNotIn("InsideInsideClassCfg", cfg.inside.__annotations__)
         # check values
         self.assertEqual(cfg.inside.class_name, DummyClass)
-        self.assertEqual(cfg.inside.b, "dummy")
+        self.assertEqual(cfg.inside.b, "dummy_changed")
         self.assertEqual(cfg.x, 20)
 
     def test_config_dumping(self):