# File lib/rubygame/events/joystick_events.rb, line 105
      def initialize( joystick_id, button )

        unless joystick_id.kind_of?(Fixnum) and joystick_id >= 0
          raise ArgumentError, "joystick_id must be an integer >= 0"
        end

        @joystick_id = joystick_id

        unless button.kind_of?(Fixnum) and button >= 0
          raise ArgumentError, "button must be an integer >= 0"
        end

        @button = button

      end