Having hacked on that codebase (the heirloom-vi project has replaced my personal ex-vi fork for my own use since) the heavy use of globals and assorted trickery

Having hacked on that codebase (the heirloom-vi project has replaced my personal ex-vi fork for my own use since) the heavy use of globals and assorted trickery means it's not the easiest thing to read. For a simple but really rather elegant piece of code, I very much enjoyed reading the sources to abduco a while back.