gistfile1.txt

    def image? #better because file_type only called once and result stored instead of recalculated?
      if ft = file_type
        ['.jpg','.jpeg'].include?(ft.downcase)
      else
        return false
      end
    end

    def image_alternative? #worse because needs to call file_type twice?
      file_type.nil? ?  ['.jpg','.jpeg'].include?(file_type.downcase) : false 
    end

    def file_type
      @filetype ||= self.scan(/(\.\w+?)\z/).flatten[0]
    end