Optional def arg

[christian-rauch]

As discussed in #561, this PR changes the initialiser code generator to require default arguments for Optional paramters.

It already triggered for the JointPose task map initiliasier (Optional parameter 'JointRef' requires a default argument!) which is a Eigen Matrix type and would load garbage values if not set by the user.

What would be a good default value for these:

exotica/exotations/exotica_core_task_maps/init/joint_pose.in

Lines 1 to 6 in 79699fc

	class JointPose
	extend <exotica_core/task_map>
	Optional Eigen::VectorXd JointRef;
	Optional Eigen::VectorXd JointMap;

or should they be Required?

Edit: I already made them Required to let the CI pass.

[wxmerkt]

I don't think they have triggered "garbage" values for JointPose since it was correctly handled in the Initialize call (and we frequently use JointPose as a default-cost with the empty optional parameters, defaulting to "all joints squared/from zero"):

exotica/exotations/exotica_core_task_maps/src/joint_pose.cpp

Lines 85 to 110 in 79699fc

	if (parameters_.JointMap.rows() > 0)
	{
	joint_map_.resize(parameters_.JointMap.rows());
	for (int i = 0; i < parameters_.JointMap.rows(); ++i)
	{
	joint_map_[i] = parameters_.JointMap(i);
	}
	}
	else
	{
	joint_map_.resize(N_);
	for (int i = 0; i < N_; ++i)
	{
	joint_map_[i] = i;
	}
	}
	if (parameters_.JointRef.rows() > 0)
	{
	joint_ref_ = parameters_.JointRef;
	if (joint_ref_.rows() != joint_map_.size()) ThrowNamed("Invalid joint reference size! Expecting " << joint_map_.size() << " but received " << joint_ref_.rows());
	}
	else
	{
	joint_ref_ = Eigen::VectorXd::Zero(joint_map_.size());
	}

I.e. since they are correctly handled in the implementation they neither need a default value nor need to be required. For double/int/other standard types, this is, of course, different - but for Eigen-types we usually handle it well.

[VladimirIvan]

These should be optional and set to empty vectors.

[wxmerkt]

I think I found another, more narrow bug related to this and will update #561 with my findings shortly. It may be limited to fixed-size Eigen types. It appears to be limited to initialising manually from Python or without going through the XML-layer.

[wxmerkt]

Having dug into the issue with the minimal example you provided it seems that there are two distinct things at play:

(a) To require Optional arguments to have a default parameter - what you are proposing to fix in this PR. This should go ahead. Please revert and fix the change to JointPose though.

(b) The fact that Required arguments are not enforced if the initializer is passed manually via Python. If you create the same example in XML, it throws.

[christian-rauch]

This PR only addresses the issue that Optional parameters should have default arguments (a). It's not related to the bug that you can initialise Required parameters without a value via a Python dict (b).
Regarding the JointPose, I did not meant to say that garbage values will be loaded. For Eigen types, a class can always check of a dynamic sized matrix has been initialised. I just meant to say that if someone uses Eigen types like this without providing a default argument (or checking if it is initialised), it would provide garbage values.

[wxmerkt]

Thank you for the fix :-) Happy to merge once CI goes green.