Stringfies class-type that prevent Cfg file eager imports implementation files dependencies

source/isaaclab/config/extension.toml

@@ -1,7 +1,7 @@
 [package]
 
 # Note: Semantic Versioning is used: https://semver.org/
-version = "4.2.2"
+version = "4.3.0"
 
 # Description
 title = "Isaac Lab framework for Robot Learning"

source/isaaclab/docs/CHANGELOG.rst

@@ -1,6 +1,22 @@
 Changelog
 ---------
 
+4.3.0 (2026-02-26)
+~~~~~~~~~~~~~~~~~~
+
+Changed
+^^^^^^^
+
+* Added lazy callable-string resolution for config fields through
+  :class:`~isaaclab.utils.string.ResolvableString` in :mod:`isaaclab.utils.configclass`.
+  Config values such as ``class_type``/``func`` can now remain as strings until first
+  use and then resolve/cached automatically.
+
+* Added ``{DIR}`` callable-string shorthand support in :mod:`isaaclab.utils.configclass`
+  for config defaults. ``"{DIR}.module:Symbol"`` now expands to the declaring config
+  module directory before resolution.
+
+
 4.2.2 (2026-02-26)
 ~~~~~~~~~~~~~~~~~~
 

source/isaaclab/isaaclab/actuators/actuator_net_cfg.py

@@ -5,19 +5,21 @@
 
 from collections.abc import Iterable
 from dataclasses import MISSING
-from typing import Literal
+from typing import TYPE_CHECKING, Literal
 
 from isaaclab.utils import configclass
 
-from . import actuator_net
 from .actuator_pd_cfg import DCMotorCfg
 
+if TYPE_CHECKING:
+    from .actuator_net import ActuatorNetLSTM, ActuatorNetMLP
+
 
 @configclass
 class ActuatorNetLSTMCfg(DCMotorCfg):
     """Configuration for LSTM-based actuator model."""
 
-    class_type: type = actuator_net.ActuatorNetLSTM
+    class_type: type["ActuatorNetLSTM"] | str = "{DIR}.actuator_net:ActuatorNetLSTM"
     # we don't use stiffness and damping for actuator net
     stiffness = None
     damping = None
@@ -30,7 +32,7 @@ class ActuatorNetLSTMCfg(DCMotorCfg):
 class ActuatorNetMLPCfg(DCMotorCfg):
     """Configuration for MLP-based actuator model."""
 
-    class_type: type = actuator_net.ActuatorNetMLP
+    class_type: type["ActuatorNetMLP"] | str = "{DIR}.actuator_net:ActuatorNetMLP"
     # we don't use stiffness and damping for actuator net
 
     stiffness = None

source/isaaclab/isaaclab/actuators/actuator_pd_cfg.py

@@ -4,12 +4,15 @@
 # SPDX-License-Identifier: BSD-3-Clause
 
 from dataclasses import MISSING
+from typing import TYPE_CHECKING
 
 from isaaclab.utils import configclass
 
-from . import actuator_pd
 from .actuator_base_cfg import ActuatorBaseCfg
 
+if TYPE_CHECKING:
+    from .actuator_pd import DCMotor, DelayedPDActuator, IdealPDActuator, ImplicitActuator, RemotizedPDActuator
+
 """
 Implicit Actuator Models.
 """
@@ -23,7 +26,7 @@ class ImplicitActuatorCfg(ActuatorBaseCfg):
         The PD control is handled implicitly by the simulation.
     """
 
-    class_type: type = actuator_pd.ImplicitActuator
+    class_type: type["ImplicitActuator"] | str = "{DIR}.actuator_pd:ImplicitActuator"
 
 
 """
@@ -35,14 +38,14 @@ class ImplicitActuatorCfg(ActuatorBaseCfg):
 class IdealPDActuatorCfg(ActuatorBaseCfg):
     """Configuration for an ideal PD actuator."""
 
-    class_type: type = actuator_pd.IdealPDActuator
+    class_type: type["IdealPDActuator"] | str = "{DIR}.actuator_pd:IdealPDActuator"
 
 
 @configclass
 class DCMotorCfg(IdealPDActuatorCfg):
     """Configuration for direct control (DC) motor actuator model."""
 
-    class_type: type = actuator_pd.DCMotor
+    class_type: type["DCMotor"] | str = "{DIR}.actuator_pd:DCMotor"
 
     saturation_effort: float = MISSING
     """Peak motor force/torque of the electric DC motor (in N-m)."""
@@ -52,7 +55,7 @@ class DCMotorCfg(IdealPDActuatorCfg):
 class DelayedPDActuatorCfg(IdealPDActuatorCfg):
     """Configuration for a delayed PD actuator."""
 
-    class_type: type = actuator_pd.DelayedPDActuator
+    class_type: type["DelayedPDActuator"] | str = "{DIR}.actuator_pd:DelayedPDActuator"
 
     min_delay: int = 0
     """Minimum number of physics time-steps with which the actuator command may be delayed. Defaults to 0."""
@@ -71,7 +74,7 @@ class RemotizedPDActuatorCfg(DelayedPDActuatorCfg):
         the output torques.
     """
 
-    class_type: type = actuator_pd.RemotizedPDActuator
+    class_type: type["RemotizedPDActuator"] | str = "{DIR}.actuator_pd:RemotizedPDActuator"
 
     joint_parameter_lookup: list[list[float]] = MISSING
     """Joint parameter lookup table. Shape is (num_lookup_points, 3).

source/isaaclab/isaaclab/assets/articulation/articulation_cfg.py

@@ -6,12 +6,15 @@
 from __future__ import annotations
 
 from dataclasses import MISSING
+from typing import TYPE_CHECKING
 
 from isaaclab.actuators import ActuatorBaseCfg
 from isaaclab.utils import configclass
 
 from ..asset_base_cfg import AssetBaseCfg
-from .articulation import Articulation
+
+if TYPE_CHECKING:
+    from .articulation import Articulation
 
 
 @configclass
@@ -38,7 +41,7 @@ class InitialStateCfg(AssetBaseCfg.InitialStateCfg):
     # Initialize configurations.
     ##
 
-    class_type: type = Articulation
+    class_type: type[Articulation] | str = "{DIR}.articulation:Articulation"
 
     articulation_root_prim_path: str | None = None
     """Path to the articulation root prim under the :attr:`prim_path`. Defaults to None, in which case the class

source/isaaclab/isaaclab/assets/asset_base.py

@@ -16,7 +16,7 @@
 import warp as wp
 
 import isaaclab.sim as sim_utils
-from isaaclab.physics import PhysicsEvent, PhysicsManager
+from isaaclab.physics import PhysicsEvent
 from isaaclab.sim.simulation_context import SimulationContext
 from isaaclab.sim.utils.stage import get_current_stage
 
@@ -381,8 +381,8 @@ def _initialize_callback(self, event):
             :attr:`PhysicsEvent.PHYSICS_READY` is dispatched by the current backend.
         """
         if not self._is_initialized:
-            self._backend = PhysicsManager.get_backend()
-            self._device = PhysicsManager.get_device()
+            self._backend = SimulationContext.instance().physics_manager.get_backend()
+            self._device = SimulationContext.instance().physics_manager.get_device()
             try:
                 self._initialize_impl()
             except Exception as e:

source/isaaclab/isaaclab/assets/asset_base_cfg.py

@@ -11,8 +11,6 @@
 from isaaclab.sim import SpawnerCfg
 from isaaclab.utils import configclass
 
-from .asset_base import AssetBase
-
 
 @configclass
 class AssetBaseCfg:
@@ -41,7 +39,7 @@ class InitialStateCfg:
         Defaults to (0.0, 0.0, 0.0, 1.0).
         """
 
-    class_type: type[AssetBase] = None
+    class_type: type | str | None = None
     """The associated asset class. Defaults to None, which means that the asset will be spawned
     but cannot be interacted with via the asset class.
 

source/isaaclab/isaaclab/assets/rigid_object/rigid_object_cfg.py

@@ -3,10 +3,14 @@
 #
 # SPDX-License-Identifier: BSD-3-Clause
 
+from typing import TYPE_CHECKING
+
 from isaaclab.utils import configclass
 
 from ..asset_base_cfg import AssetBaseCfg
-from .rigid_object import RigidObject
+
+if TYPE_CHECKING:
+    from .rigid_object import RigidObject
 
 
 @configclass
@@ -26,7 +30,7 @@ class InitialStateCfg(AssetBaseCfg.InitialStateCfg):
     # Initialize configurations.
     ##
 
-    class_type: type = RigidObject
+    class_type: type["RigidObject"] | str = "{DIR}.rigid_object:RigidObject"
 
     init_state: InitialStateCfg = InitialStateCfg()
     """Initial state of the rigid object. Defaults to identity pose with zero velocity."""

source/isaaclab/isaaclab/assets/rigid_object_collection/rigid_object_collection_cfg.py

@@ -4,18 +4,20 @@
 # SPDX-License-Identifier: BSD-3-Clause
 
 from dataclasses import MISSING
+from typing import TYPE_CHECKING
 
 from isaaclab.assets.rigid_object import RigidObjectCfg
 from isaaclab.utils import configclass
 
-from .rigid_object_collection import RigidObjectCollection
+if TYPE_CHECKING:
+    from .rigid_object_collection import RigidObjectCollection
 
 
 @configclass
 class RigidObjectCollectionCfg:
     """Configuration parameters for a rigid object collection."""
 
-    class_type: type = RigidObjectCollection
+    class_type: type["RigidObjectCollection"] | str = "{DIR}.rigid_object_collection:RigidObjectCollection"
     """The associated asset class.
 
     The class should inherit from :class:`isaaclab.assets.asset_base.AssetBase`.

source/isaaclab/isaaclab/controllers/differential_ik_cfg.py

@@ -6,18 +6,19 @@
 from __future__ import annotations
 
 from dataclasses import MISSING
-from typing import Literal
+from typing import TYPE_CHECKING, Literal
 
 from isaaclab.utils import configclass
 
-from .differential_ik import DifferentialIKController
+if TYPE_CHECKING:
+    from .differential_ik import DifferentialIKController
 
 
 @configclass
 class DifferentialIKControllerCfg:
     """Configuration for differential inverse kinematics controller."""
 
-    class_type: type = DifferentialIKController
+    class_type: type[DifferentialIKController] | str = "{DIR}.differential_ik:DifferentialIKController"
     """The associated controller class."""
 
     command_type: Literal["position", "pose"] = MISSING

source/isaaclab/isaaclab/controllers/operational_space_cfg.py

@@ -7,17 +7,19 @@
 
 from collections.abc import Sequence
 from dataclasses import MISSING
+from typing import TYPE_CHECKING
 
 from isaaclab.utils import configclass
 
-from .operational_space import OperationalSpaceController
+if TYPE_CHECKING:
+    from .operational_space import OperationalSpaceController
 
 
 @configclass
 class OperationalSpaceControllerCfg:
     """Configuration for operational-space controller."""
 
-    class_type: type = OperationalSpaceController
+    class_type: type[OperationalSpaceController] | str = "{DIR}.operational_space:OperationalSpaceController"
     """The associated controller class."""
 
     target_types: Sequence[str] = MISSING

source/isaaclab/isaaclab/devices/gamepad/se2_gamepad_cfg.py

@@ -8,9 +8,12 @@
 from __future__ import annotations
 
 from dataclasses import dataclass
+from typing import TYPE_CHECKING
 
 from ..device_base import DeviceCfg
-from .se2_gamepad import Se2Gamepad
+
+if TYPE_CHECKING:
+    from .se2_gamepad import Se2Gamepad
 
 
 @dataclass
@@ -21,4 +24,4 @@ class Se2GamepadCfg(DeviceCfg):
     v_y_sensitivity: float = 1.0
     omega_z_sensitivity: float = 1.0
     dead_zone: float = 0.01
-    class_type: type | str = Se2Gamepad
+    class_type: type[Se2Gamepad] | str = "{DIR}.se2_gamepad:Se2Gamepad"

source/isaaclab/isaaclab/devices/gamepad/se3_gamepad_cfg.py

@@ -8,9 +8,12 @@
 from __future__ import annotations
 
 from dataclasses import dataclass
+from typing import TYPE_CHECKING
 
 from ..device_base import DeviceCfg
-from .se3_gamepad import Se3Gamepad
+
+if TYPE_CHECKING:
+    from .se3_gamepad import Se3Gamepad
 
 
 @dataclass
@@ -21,4 +24,4 @@ class Se3GamepadCfg(DeviceCfg):
     dead_zone: float = 0.01
     pos_sensitivity: float = 1.0
     rot_sensitivity: float = 1.6
-    class_type: type | str = Se3Gamepad
+    class_type: type[Se3Gamepad] | str = "{DIR}.se3_gamepad:Se3Gamepad"

source/isaaclab/isaaclab/devices/keyboard/se2_keyboard_cfg.py

@@ -8,9 +8,12 @@
 from __future__ import annotations
 
 from dataclasses import dataclass
+from typing import TYPE_CHECKING
 
 from ..device_base import DeviceCfg
-from .se2_keyboard import Se2Keyboard
+
+if TYPE_CHECKING:
+    from .se2_keyboard import Se2Keyboard
 
 
 @dataclass
@@ -20,4 +23,4 @@ class Se2KeyboardCfg(DeviceCfg):
     v_x_sensitivity: float = 0.8
     v_y_sensitivity: float = 0.4
     omega_z_sensitivity: float = 1.0
-    class_type: type | str = Se2Keyboard
+    class_type: type[Se2Keyboard] | str = "{DIR}.se2_keyboard:Se2Keyboard"

source/isaaclab/isaaclab/devices/keyboard/se3_keyboard_cfg.py

@@ -8,9 +8,12 @@
 from __future__ import annotations
 
 from dataclasses import dataclass
+from typing import TYPE_CHECKING
 
 from ..device_base import DeviceCfg
-from .se3_keyboard import Se3Keyboard
+
+if TYPE_CHECKING:
+    from .se3_keyboard import Se3Keyboard
 
 
 @dataclass
@@ -21,4 +24,4 @@ class Se3KeyboardCfg(DeviceCfg):
     pos_sensitivity: float = 0.4
     rot_sensitivity: float = 0.8
     retargeters: None = None
-    class_type: type | str = Se3Keyboard
+    class_type: type[Se3Keyboard] | str = "{DIR}.se3_keyboard:Se3Keyboard"

source/isaaclab/isaaclab/devices/spacemouse/se2_spacemouse.py

@@ -19,10 +19,10 @@
 from isaaclab.utils.array import convert_to_torch
 
 from ..device_base import DeviceBase
+from .utils import convert_buffer
 
 if TYPE_CHECKING:
     from .se2_spacemouse_cfg import Se2SpaceMouseCfg
-from .utils import convert_buffer
 
 
 class Se2SpaceMouse(DeviceBase):

source/isaaclab/isaaclab/devices/spacemouse/se2_spacemouse_cfg.py

@@ -8,9 +8,12 @@
 from __future__ import annotations
 
 from dataclasses import dataclass
+from typing import TYPE_CHECKING
 
 from ..device_base import DeviceCfg
-from .se2_spacemouse import Se2SpaceMouse
+
+if TYPE_CHECKING:
+    from .se2_spacemouse import Se2SpaceMouse
 
 
 @dataclass
@@ -20,4 +23,4 @@ class Se2SpaceMouseCfg(DeviceCfg):
     v_x_sensitivity: float = 0.8
     v_y_sensitivity: float = 0.4
     omega_z_sensitivity: float = 1.0
-    class_type: type | str = Se2SpaceMouse
+    class_type: type[Se2SpaceMouse] | str = "{DIR}.se2_spacemouse:Se2SpaceMouse"