Re: ADC Core Data article

FROM : Scott Stevenson
DATE : Wed Apr 06 18:00:38 2005

On Apr 6, 2005, at 5:47 AM, Philip Mötteli wrote:

>> Trying to implement transparent persistence without a persistent
>> subclass is.... challenging.

>
> We had it with EOF, including un-/redo.
> I wouldn't say, it's challenging. It's a lot of work, but we could
> even go much further. We wouldn't even need a model.


I think we're probably splitting hairs in terms of the definition of
"challenging" and "a lot of work."

Adding a persistent base class solves a lot of the more complicated
issues. I didn't require it in DataCrux for the very reason that I
thought people wouldn't want to change their class hierarchy. If I was
starting from scratch now, I would absolutely require it.


>> The reason that NSManagedObject is distinct from NSObject, is that
>> there are many situations where persistence isn't needed or wanted. 
>> You should derive your model objects from NSManagedObject, not every
>> object in your apps.

>
> I thought you define that in your model? All the classes, that are in
> the model, are entities in the DB.

[...]
> Please correct me, if I'm wrong, but I don't really see, what Core
> Data has more to offer than EOF? I see though, that it seems to be a
> cleaner and compacter implementation of a part of EOF, by leveraging
> some new technologies.


EOF was used for centralized databases. Core Data is similar to EOF,
but is obviously aimed at desktop applications. The fact that there's
no centralized store changes the game somewhat.


    - Scott

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