Implementation details

[schriftgestalt]

It would be nice to have some suggestions how things are supposed be implemented. Some example code with resulting ttx would be great. That would make it easier to develop consisted fea compilers.
Maybe even some unit tests we all can run our implementation agains?

[skef]

We are definitely working on tests, and we are attempting to construct them so that they will work across implementations. This is new for AFDKO-related stuff, so we have to develop a bit of infrastructure.

It might be a while before those are available, however. (I can't make commitments on this, but I'm hoping it will be a matter of a couple months at most.)

I think the tests can also fill the role of implementation advice, maybe better than the alternatives. One can always run the tests with the FDK and use ttx on the output for some clarity. However, "exact" implementation advice would be counter-productive because itemVariationStore output can be optimized in various ways, and other implementations might do better on that than we do.
It will have to be a balance.