As promised, here is a link to the source for a simple OOT module/block that works on GNU Radio 3.9. The code shows how to handle variable # of inputs, and how to setup a callback when a parameter changes during runtime. You can find the block at: https://github.com/eejake52/gr-stream There is a branch for the version that worked on 3.7, but I didn't make a branch for 3.8. Hope that helps someone.
Jake
