From: Tony Headford <tony@...>
Date: 2006-02-14T06:34:35+09:00
Subject: Re: OO Design Advice

Jeff Cohen wrote:
> unknown wrote:
> 
>>I'm trying to master the more subtle elements of Rubyish OO design, and
>>am having trouble with the following aspect:
>>
>>I have a complicated, nested, value object ( eg
>>order.customer.address.zipcode, or order.product[0].description).
>>
>>This object needs to be sent to various feeds (usually XML, sometimes
>>REST / HTTP form ) run by other companies.  
> 
> 
> I say, you should definitely abstract away the "rendering" of the data 
> from the data model itself.  I would recommend reading up a bit on the 
> "strategy" design pattern, but basically the idea is to take something 
> that varies (i.e. your feed formatting) and separate it from the things 
> that don't vary (your data model).
> 
> So to render your data for a particular feed, you just instantatiate the 
> particular renderer that you need for that feed, pass it an instance of 
> your data, and then let the renderer worry about all of the formatting.
> 
> Make sense?  I can elaborate more if that would be helpful.
> 
> Jeff
> www.softiesonrails.com
> 
In my experience what Jeff suggests is the right OO way to go.  The 
model does not need to know how to render itself for specific feeds, 
that would be a function of the feeds themselves or an adapter class.

cheers,
Tone.