Re: EOKeyValueCoding

[Richard Frith-Macdonald]

On Wednesday, November 14, 2001, at 12:05 PM, Gerrit Van Dyk wrote:

> Hi all,
>
> On the DB Library subject, if i change the DB Library to use
> NSKeyValueCoding instead of EOKeyValueCoding, should I transfer the 
> methods
> in EOKeyValueCoding to valueForKey in Foundation or should I stay with 
> the
> implementation of Foundation? It just looked to me, I did not 
> investigate,
> that the methods that does essentially the same as valueForKey in the DB
> library, is better implemented ie uses caching of method names, ivar's 
> etc
> to enable valueForKey to get to the answer quicker.

Unfortunately not quite that simple ...

the code in the db library suffers from various faults wrt the code in 
NSObject -
1. It's old, and does not conform to the currently documented API, so 
would need updating
2. It's not thread-safe (the cache needs lock protecting)
3. Access to instance variables is runtime dependent
4. Some bugs known ... but probably not significant ones ... for 
instance, this code won't
work if the accessor methods are performed by a delegate or if the 
object is a proxy for
another object (but who cares?)

As far as I know, the code in NSObject only has one fault - but it's a 
biggie - it's *very*
slow by comparison with the db code.

So what really needs to be done is for new code to be written.

I'd suggest it is probably easier to start with the NSObject code and 
optimise and implement
thread-safe caching than it is to work from the other end, simply 
because the NSObject code
is (because it's unoptimised) easier to understand.