Re: NSUnarchiver extensions

[Pierre-Yves Rivaille]

> Unless I'm missing something, I think the change is pointless (and therefore
> bloat).
> It seems to me that if you are substituting one class for another when
> decoding, the replacement class
> *must* know all about the class it is replacing.

The problem is that the initWithCoder is used to decode GSCustomView object 
*and* GormCustomView object too.
And there is no easy way to know if I'm decoding a GSCustomView or a 
GormCustomView, so I don't know if I should call [aCoder versionForClassName: 
@"GSCustomView"] or [aCoder versionForClassName: @"GormCustomView"].
Calling the wrong [aCoder versionForClassName: @"..."] leads to a segfault.

Another way to do thing would be to patch the [NSUnarchiver 
versionForClassName:] methods so that it returns a specific value when the 
class does not exist in the archive (maybe NSNotFound, but it may interact 
with some class's version, although it is unlikely), or maybe raise an 
exception. (I've implemented the first solution at some point but I dumped it 
for some reason I forgot ..., but i've never played with exceptions in objc).

(The dirty trick solution would be to turn on and off a class variable for 
GormCustomView before and after loading a nib file, so that it knows when it 
is used to decode a GSCustomView or a GormCustomView.)

        Pierre-Yves