get Enumerable involved
class AllVowels include Enumerable @@vowels = %w{a e i o u} def each @@vowels.each { |v| yield v } end end x = AllVowels.new x.collect { |i| i + "x" } x.detect { |i| i > "j" } x.select { |i| i > "j" } x.sort x.max x.min