[Zope-dev] Questions about implementing object models with ZPatterns

[Itai Tavor]

Hi,

How do I implement gen-spec classes using ZPatterns and ZClasses? 
For example, I want to implement Person and Customer. Writing it in 
Python, it would be easy to subclass Person to get Customer, and 
Customer would inherit Person's properties and methods. If I instead 
create a specialist and ZClass for each class, do I use a SkinScript 
to remap Person's properties into Customer? And what about the 
methods - Customer can't inherit Person's methods, so I have to write 
methods in Customer which call the same methods in Person. This seems 
terribly complicated... am I missing something?

Another question: In Coad's examples, if a class has an 'n' order 
relationship to another class - say Order and OrderItems, Order would 
contain a list of OrderItems. Each OrderItem would contain the id of 
the Order it belongs to. It seems to me that it would be easier for 
Order to call OrderItems.getItemsForOrder(self.id), then I don't have 
to maintain a list in Orders, and if I add an OrderItem the Order 
will immediately know about it without me having to call it and tell 
it the OrderItem was added. Is there anything wrong with this 
approach?

TIA,

Itai
-- 
Itai Tavor                    "Je sautille, donc je suis."
C3Works    itai@c3works.com              - Kermit the Frog

"If you haven't got your health, you haven't got anything"