Re: ABI Compatibility (was Re: Installation woes for the average user...)

[Fred Kiefer]

Xavier Glattard wrote:
> The problem comes from ivars that would not be always at the same
> offset, doesn't it ? But these ivars are supposed to be private, dont
> they ? So the code that uses these ivars is always released along with
> the class interface. I can not find any official 'public' ivars. Do i
> miss something ?
> 
> And if the ivars need to be used from outside the library/bundle (for
> internal use), why not access them thru accessors? Obj-C accessors (KVC)
> or even simple&fast C functions that would read or write the value, or
> return a pointer, or even a member pointer (offset)...
> 

The problem is with subclasses, say you have a subclass of NSCell and
GNUstep changes the ivar layout of NSCell by adding a new ivar. You will
have to recompile your application with your subclass of NSCell to adopt
to our change. What Greg, Richard and David are looking for are
different solutions for this problem.

Fred