Shoes3 is an old, creaky codebase from the Ruby 1.8 days. When working on Scarpe, I get to read through it a lot to answer questions like, “what methods can you call on a Button?” or “what is self supposed to be here?”
It provides a fun code reading challenge. I recorded a video to help folks who work on Scarpe with the code reading. But it can be useful for all sorts of computer programmers.
The Ruby/C interface that it’s using is basically the same now as it was then, and it’s what’s used by native extensions. Peter Zhu’s series of articles A Rubyist’s Walk Along the C-side can also be really valuable here since it’s using the same APIs.