Make CostConfig's have their own copies of weights?

[YuhengZhi]

We noticed that if multiple costs are initialized using the same cost_cfg, their weights share the same tensors under the hood. So changing one cost's weights will implicitly change the other costs' weights sharing the same torch tensors.

[balakumar-s]

Is there a reason to share the same instance of CostConfig between costs? It's a dataclass and they are expected to be created separately per cost.

[YuhengZhi]

share the same instance of CostConfig between costs

This appeared briefly in here. So 1) if link_pose_cfg isn't specified, links' pose costs would be initialized by the goal_cost_cfg (though this is a deprecated feature) and 2) if multiple non-ee links have pose costs they would be sharing the same link_pose_cfg as well?

Just to provide a bit of context, e.g., in sequential planning like the constrained_reacher example, if one wanted to change constraints for a particular non-ee link and they call _link_pose_costs[link_name].hold_partial_pose, this would change the run_vec_weight for all _link_pose_costs unintentionally.

However, I personally prefer being able to create multiple Cost instances using the same CostConfig like how is done here for the link_pose_costs rather than having to do something like Cost(CostConfig.clone()).

Adding a few clone()'s in CostConfig and PoseCostConfig's __post_init__ solved the issue for me.