Emacs Ruby autocomplete almost working

Here's a thought: The macro binds a flet function (rails-project:root) one time to the value that (rails-project:root) has just before the body executes. (That's how it claims a performance increase: Apparently the outer (rails-project:root) is expensive, so calling once and caching the value seems like a good idea.)

Unfortunately, if there is code inside the body that has a side effect meant intentionally to change the value that (rails-project:root) returns, it's going to have no effect. That change will be invisible even to other code called within the body because Emacs lisp has dynamic binding of flet names.