From: "ara.t.howard" <ara.t.howard@...>
Date: 2007-10-06T00:58:33+09:00
Subject: Re: Refering to an object's 'parent'


On Oct 5, 2007, at 8:36 AM, Toby Rodwell wrote:

> class House(type)
>   attr_accessor :rooms, :type_of_house
>   @rooms = []
>   ...
>   def type_of_house
>     type
>   end
> end
>
> class Room
> ...
> end
>
> my_room = Room.new
>
> my_house = House.new
>
> my_house.rooms.push(my_room)
>
> ... then is it somehow possible to ask ...
> my_room.<PARENT>.respond_to?(type_of_house) ?
> (I know 'House' is not really the parent of 'Room', and so I  
> suspect the
> answer is "no", but it can't hurt to ask.  Thanks.

sure.

cfp:~ > cat a.rb
class House
   attr_accessor :rooms, :type_of_house

   def initialize
     @rooms = Room::List.new self
   end

   def type_of_house
     type
   end

   class Room
     attr_accessor :parent

     class List < ::Array
       attr_accessor :house
       def initialize house
         @house = house
       end
       def push room
         super
       ensure
         room.parent = house
       end
     end
   end
end

my_room = House::Room.new

my_house = House.new

my_house.rooms.push(my_room)

p my_room.parent.respond_to?(:type_of_house)

cfp:~ > ruby a.rb
true


probably better design to make a room factory for house though:

cfp:~ > cat a.rb
class House
   attr_accessor :rooms, :type_of_house

   def initialize
     @rooms = []
   end

   def type_of_house
     type
   end

   def new_room
     rooms.push(Room.new(self)).last
   end

   class Room
     attr_accessor :house

     def initialize house
       @house = house
     end
   end
end


my_house = House.new

my_room = my_house.new_room

p my_room.house.respond_to?(:type_of_house)

cfp:~ > ruby a.rb
true



kind regards.



a @ http://codeforpeople.com/
--
share your knowledge.  it's a way to achieve immortality.
h.h. the 14th dalai lama