From: Wes Oldenbeuving <wesley@...>
Date: 2006-07-19T22:35:05+09:00
Subject: Re: Objects within objects... ??

On Wed, 19 Jul 2006 14:56:24 +0200, Brandon Coleman <metrix1978@gmail.com>  
wrote:

> Yes it is! but I would like to be able to add and delete objects on the
> fly.  For instance I want to add Toyota: could the objects be stored in
> an array so that I could add an object and delete an object when I
> needed?

I think that the easiest way to achieve something like this is to use a  
hash.

Another way would be to try and setup something with  
Kernel#method_missing. That way you could redirect invalid method calls to  
the hash, or whichever way you use to track things internally. The docs  
for Kernel#method_missing:  
http://www.ruby-doc.org/core/classes/Kernel.html#M002946

Here is an example using both methods:

----- Code -----

class Dealership
   def initialize
     @items=Hash.new
   end
   def add(name,new_item)
     @items[name]=new_item
   end
   def [](name)
     @items[name]
   end
   def method_missing(methId)
      str = methId.id2name
      self.[](str)
   end
end

class Honda
   def to_s
     return "Honda"
   end
end

class Ford
   def sound_horn
     puts "You sound the Ford's horn!"
   end
end

dealership_obj = Dealership.new

dealership_obj.add("honda", Honda.new)
dealership_obj.add("ford", Ford.new)

puts dealership_obj["honda"]
dealership_obj["ford"].sound_horn
dealership_obj.ford.sound_horn


----- End code -----


> Talking about it brought me to this example:
>
> dealership.modify(toyota.modify(shelfb.add(bin1.new(carburetor)))).
>
> which IS what I think I would like to do, I just think that code is ugly
> and illedgible, and so I feel there is probably a better way.


By putting the hash and method_missing inside the car brand classes and  
classes that will be contained by them, your given example would look like:

dealership.toyota.shelfb.add('bin1',Bin1.new(carburetor))


Cheers,


Wes