Re: ADC Core Data article

FROM : Johnny Deadman
DATE : Fri Apr 08 14:10:22 2005

Wow, that's a lot of bitching.

I'd say, looking at the article, that having a managed object class 
is an excellent idea since it enforces some further rigor into the 
cocoa paradigm. Every day on this list we see people who are in 
trouble because they are confused about the MVC paradigm. Currently 
in cocoa nobody is confused about what constitutes a view because it 
generally inherits from NSView (or NSResponder). The confusion is 
between controller classes and data classes.

Now with Coredata it seems likely from the article that just as one 
of the first steps in creating an app is to prototype the interface 
in Interface Builder, we will head into Xcode and create a data model 
for the persistence layer.

Here's the big point: not everything should be a persistent object.

Should everything be an NSResponder? Should NSResponding have been a 
category on NSObject? Hardly. Why is being part of the persistent 
model different?

The one thing that I think would have been a disaster would be to 
have made the Coredata behavior some kind of category on NSObject. 
Converting current apps to utilize Coredata is unlikely to be trivial 
since sloppy implementation of the MVC paradigm will cause a horrible 
mess. In most cases where the implementation of MVC has been less 
than perfect my guess is it is likely to require non-trivial 
reconfiguration of the object graph. In many cases it may require a 
wholesale overhaul of the app.

  Simply slapping a category on your existing classes would be a 
horrible kludge and, more to the point, wouldn't work.

Anyway, I know that the whole point of the internet is to let 
customers let suppliers know how much cleverer they are and how much 
better they could have made their product if only they had been 
consulted, but still...

best,

JB