Wrong type returned when calling FromPython function

[isorrentino]

Here an example. If I run this code:

x_py = numpy.zeros(6)
x_idyn = idyn.JointPosDoubleArray(6)
x_idyn = x_idyn.FromPython(x_py)

x_idyn becomes a VectorDynSize object. Maybe, this happens because the FromPython function that is actually called is the one defined in

idyntree/bindings/python/python.i

Line 184 in 163cff7

static iDynTree::VectorDynSize FromPython(double* in, int size) {

.

[traversaro]

Good point. This is a nasty effect of the fact that .FromPython method is a function that returns a new instance of the type, instead of populating the instance on which it is called (as .fromMatlab does). I am not sure why this happened back in time, but the quickest solution for your use case is to add a FromMatlab overload for JointPosDoubleArray, as done for example in #959 for iDynTree::Position.

[traversaro]

An alternative may be to define a .FromPythonInPlace method for iDynTree::VectorDynSize (better name suggestions are welcome) that populate the existing vector instead of returning a new one (a bit like .fromMatlab do), and then use this new method in JointPosDoubleArray.