[Zope-dev] Implementing [XOR A] 1 object connections in ZPatterns

[Itai Tavor]

Steve Spicklemire wrote:

>  >>>>> "Itai" == Itai Tavor <itai@optusnet.com.au> writes:
>
>...
>
>     Itai> The 2nd way seems to go better with OO principles - all
>     Itai> handling of photos is delegated to the Photos Specialist and
>     Itai> the Product doesn't care if the photo exists or not, or
>     Itai> where it comes from. But it also increases complexity in
>     Itai> Photos, because I need to implement an efficient way to
>     Itai> retrieve photos (with a Catalog, or SQL searches), and
>     Itai> because it introduces the photo_key. Storing photo_id in
>     Itai> Product eliminates these complexities, but it moves some of
>     Itai> the responsibility for managing photos into Product.
>
>Hmmm.. it seems to me that it makes more sense for the Product
>to know the id of the Photo that *it* needs to display itself than
>for the Photo to have to know that it belongs to a particular
>Product. Also.. I can imagine that the Photo class might be useful
>for lots of other things besides Products, and how would you teach
>it what type of object it belongs to?

Actually, my Photo object really is used for other things besides 
Products, which is where my problems with XOR connections come in... 
I myself prefer the first method (Product knowing the id of its 
Photo), but I've been bitten a lot recently by placing 
responsibilities outside the classes where they belong, so I'm trying 
hard to make sure I don't do it again.

>
>Just my $0.02.

It's worth more than that to me :)
-- 
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"