# File lib/rubygame/events/joystick_events.rb, line 209 def initialize( joystick_id, ball, rel ) 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 ball.kind_of?(Fixnum) and ball >= 0 raise ArgumentError, "ball must be an integer >= 0" end @ball = ball @rel = rel.to_ary.dup @rel.freeze unless @rel.length == 2 raise ArgumentError, "rel must have exactly 2 parts (got %s)"%@rel.length end end