From: ts Date: 2001-11-22T14:59:46+09:00 Subject: [ruby-talk:26112] Re: string concat and .to_s >>>>> "R" == Ralph Mason writes: R> eval ("class String; alias plus + ; end") unless String.methods.include? R> "plus" You have defined an instance method not a class method, try with String.instance_methods.include? "plus" Guy Decoux