More advanced example of Simple Message Passing

MessagePassing2.rb

class GameState
   include Subscriber

   def initialize(repeater)
      @repeater = repeater
      @repeater.subscribe(self)
   end
      
   # Handle only messages of attempt move, ignore the rest
   def accept(message)
      case message[:command]
      when "attempt move"
         if validateMove(message[:color], message[:x], message[:y])
            update_move(message[:color], message[:x], message[:y])
            @repeater.broadcast({
               command: "accept move",
               color: message[:color],
               x: message[:x],
               y: message[:y]
            })
         else
            @repeater.broadcast({
               command: "illegal move",
               color: message[:color],
               x: message[:x],
               y: message[:y]
            })
         end
      else
      end
   end
   
   # Check if move is in valid range
   def validateMove(color, x, y)
      if x > 0 && x <= 19 && y > 0 && y <= 19
         return true
      end
      return false
   end
   
   # Updates the game state on valid move
   def update_move(color, x, y)
      puts "#{self.class} State updated: #{color} moved at (#{x},#{y})"
   end
end

class GameGUI
   include Subscriber

   def initialize(repeater)
      @repeater = repeater
      @repeater.subscribe(self)
   end
      
   def accept(message)
      case message[:command]
      when "accept move"
         draw_move(message[:color], message[:x], message[:y])
      when "illegal move"
         alert_player("Illegal move", message[:color])
      else
         # do nothing
      end
   end
   
   # When a player (color) clicks on board location
   # x,y we attempt a move by broadcasting it
   def on_click(color, x, y)
      message = {
         command: "attempt move",
         color: color,
         x: x,
         y: y
      }

      @repeater.broadcast(message)
   end
   
   # This is where the real draw code would go!
   def draw_move(color, x, y)
      puts "#{self.class} drew #{color} at (#{x},#{y})"
   end
   
   # Send an alert to the player that their move was illegal
   def alert_player(message, color)
      puts "#{self.class} ALERT #{color}: #{message}"
   end   

end

r = Repeater.new
gui = GameGUI.new(r)
state = GameState.new(r)

gui.on_click("black", -1, 23) # illegal move
gui.on_click("black", 3, 8) # legal move