Fixes configclass dict conversion for torch tensors

[lgulich]

Description

Fix configclass dict conversion for torch tensors

Up to v1.2.0 if a configclass would contain a list/tuple of torch
tensors it would be left as is.

#1227 changed the behavior of converting lists/tuples in a dict, which
means that currently torch tensors are converted to an empty dict,
effectively losing all contained data.

The underlying issue is that torch.tensor.__dict__ returns an empty
dict, which was (luckily) ignored previously because we did not convert
the contents of lists.

This MR fixes this by treating torch tensors specially. I don't like
having a special case for a non-builtin class but given that
IsaacLab is heavily married with torch tensors I think it's ok in this
case.

Since currently the behavior is different between 1.2 and 1.3: can we cherry pick this change to the 1.3 branch?

Type of change

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

Checklist

• I have run the pre-commit checks with ./isaaclab.sh --format
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I have updated the changelog and the corresponding version in the extension's config/extension.toml file
• I have added my name to the CONTRIBUTORS.md or my name already exists there

[mschweig]

Hi @lgulich, @kellyguo11

this PR causes issues with rsl_rl/train.py and Boston Dynamics Spot joint_parameter_lookupwhich is torch.tensor

https://github.com/isaac-sim/IsaacLab/blob/main/source/extensions/omni.isaac.lab_assets/omni/isaac/lab_assets/spot.py

In this case torch.tensor.__dict__ does not return an empty dict and this works in 1.3.0.

This PR changes the behavior and returns the tensor object instead of converting obj.__dict__ to a dict.
But this implementation raises a omegaconf exception with rsl_rl train:

File "/home/manuel/miniconda3/envs/isaac/lib/python3.10/site-packages/omegaconf/nodes.py", line 154, in _validate_and_convert_impl raise UnsupportedValueType( omegaconf.errors.UnsupportedValueType: Value 'Tensor' is not a supported primitive type full_key: env.scene.robot.actuators.spot_knee.joint_parameter_lookup object_type=dict

I am quite new to Isaac Lab, however would be happy to help and fix this one.

[lgulich]

Hi @mschweig

I'm happy to help. Any chance you could add a unit test in this file?

Then I can take a look to make sure that it's fixed.

[mschweig]

Hi @lgulich

sure, gonna add a dummy ActuatorCfg and a unittest that checks if the __dict__ conversion does not return an empty dict.

[mschweig]

Hi @lgulich

added a unittest and created a PR:

#1608

The test fails as I expect according to my understanding. Should I open a issue to track it?