gistfile1.rb

module ExtendedMeta
    
    def extended_by
      ancestors = class << self; ancestors end
      ancestors.select { |mod| mod.class == Module } - [ Object, Kernel ]
    end
    
    # just like kind_of? but can use a string instead of a module/constant
    def extended_by?(mod)
      begin
        scope = mod.split('::').select do |v|
          ! v.empty?
        end.inject(Kernel) do |scope, const_name|
          scope.const_get(const_name)
        end
        extended_by.include?(scope)
      rescue NameError
        false
      end
    end
    
end