We've all heard the admonitions: "Don't Repeat Yourself!" But how do you avoid this if you're working on a Ruby codebase that stretches to thousands of lines, maintained by multiple developers? One answer is to run a tool that looks for duplicate code. This is an area where good tools are tantalizingly close - there are at least three out there that are worth checking out:

Towelie

The first contender is Giles Bowkett's Towelie, which uses parsetree and ruby2ruby to look through a…