On Feb 29, 2008, at 9:52 AM, Eric Mahurin wrote: > I think this is the worst kind of monkey-patching - breaking existing > functionality. I didn't realize facets went to this level. > Another reason > to never touch it. What existing functionality? Standard Ruby doesn't define Hash#-. One of the strange aspects of this discussion is that monkey patching core classes is seen as dangerous *except* when Matz and Co. decide to add something to the core classes. Then it is seen as an example of elegant library design. Fortunately, Matz is pretty good at making those decisions. I don't think the problem is with the ability to modify core classes per se but with the difficulty of managing library evolution in a distributed context. Gary Wright