RExpression2 - handle arbitrary R data structures
Not everything in R fits into the Ptolemy types (nor the JRI types, for that matter).
The lm() method, for instance, returns something special.
It's been proposed (a few times) that there should be an RObjectToken to handle such cases so that at least R actors can communicate between each other with out loss/mutation of data.
The RExpression1 actor used file-based serialization to get around this limitation. We could attempt to use a hybrid approach for RExpression2 - mixing JRI with file-based serialization (best of both worlds?).