pacman-singleton.rb

class Pacman
  
  def self.get_instance
    # instantiate the singleton instance if it is not existing yet.
    if @instance.nil?
      @instance = Pacman.new
    end
    
    @instance
  end
  
  def initialize x, y
    @x = x
    @y = y
  end
  
  def move_up
    @y = @y + 1
  end
  
  def move_down
    @y = @y - 1
  end
  
  def move_right
    @x = @x + 1
  end
  
  def move_left
    @x = @x - 1
  end
  
end