"Hal E. Fulton" <hal9000 / hypermetrics.com> writes: > > And yet, this can't be the whole story, since the TypeErrors do > > happen. Further detective work (and/or clarification by those ahead > > of me in the process :-) required.... > > I've wondered about this too... Dave, could this be considered a bug > in The Book? Perhaps, but I don't think so. to_str is not the same as to_s. to_str only works on things that pretend to be Strings in the first place (String and Exception are two basic classes), so you'll get a type error if you use anything else. Dave