Re: multiple inheritance equivalent in Core Data?
Re: multiple inheritance equivalent in Core Data?
- Subject: Re: multiple inheritance equivalent in Core Data?
- From: mmalcolm crawford <email@hidden>
- Date: Mon, 9 May 2005 11:35:58 -0700
On May 9, 2005, at 9:48 AM, glenn andreas wrote:
On May 9, 2005, at 11:40 AM, John Timmer wrote:
I don't have Tiger yet and haven't looked at CoreData much but I
hope
that won't matter much. Under Panther I would use protocols to
encapsulate these behaviors because a class can conform to multiple
protocols.
To be more clear, in every place I said "keys", you could read
"instance
variables". My understanding is that neither protocols or
categories can
add instance variables to a class, so that neither of these would
work for
this situation.
If you always access instance variables via accessors, categories
can add them to a class (by maintaining the state in a separate
data structure).
If the attributes are intended to be persistent, then this in and of
itself won't help. They still have to be defined as attributes in
the model.
The overhead of adding what are effectively unused attributes to a
model should not exactly over-tax the system, however I'm not sure in
what sense you're wanting to "simplify the object graph"? What
problem is there with adding the attributes to just those entities
that need them?
mmalc
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