From: Dave Burt <dave@...>
Date: 2006-04-27T20:30:38+09:00
Subject: Re: object available in one class but not another?

Greg Coit wrote:
> Playing around more with rrobots.
> ...
> Here's my code:
> 
> http://rafb.net/paste/results/RtkFqy50.html
> 
> Thanks for any and all help.

Hi Greg,

I'm going to ignore your question in hope that this advice is as useful
as an answer would be.

Don't include Robot in Radar or Gun. That type of relationship is "a Gun
is a kind of Robot", which is not what you want. GoofeyDuck is your Robot.

(Your problem is probably related to the fact that, for example,
radar_heading inside a Radar object refers to that Radar's radar,
whereas the parent GoofeyDuck has a separate radar. You have 4 robots, 3
inside the other 1!)

Here's an alternative skeleton, with only 1 robot per robot:

class GoofeyDuck
  include Robot

  def initialize
    @radar = Radar.new(self)
    @gun = Gun.new(self)
    @tank = Tank.new(self)
  end

  # This defines a class named GoofeyDuck::Radar.
  # You can refer to it as Gun inside GoofeyDuck's definition.
  class Radar
    def initialize(robot)
      @robot = robot
    end
    def target?
      puts @robot.radar_heading
      @robot.radar_heading + (@scan / 2)
    end
    #...
  end

  class Tank
    def initialize(robot)
      @robot = robot
    end
    #...
  end

  class Gun
    def initialize(robot)
      @robot = robot
    end
    #...
  end
end

Cheers,
Dave