ObjC runtimes (was Re: objc gnu runtime losage)

[Stan Shebs <shebs at apple dot com>]

Zack Weinberg wrote:
> 
> Why do we have two ObjC runtimes, anyway?  Is there a good reason to
> prefer one over the other?

It's a sad story of GNU politics some years ago, of which I only
know a little bit.  The NeXT runtime was the original, but
although the compiler was contributed, the runtime was not, and
eventually other people wrote a workalike, which is the GNU runtime.
However, they didn't try to make it strictly compatible, and the two
have drifted further apart, for instance Apple inherited the NeXT
runtime (which is now open-source, the "objc4" project in Darwin),
and has been hacking on it to get more performance.

Personally, I think it's lame to have incompatible runtimes, but
the situation has become entrenched, and it would be some work
to engineer a compromise, not least because part of the runtimes'
APIs are exposed - so NexT/Mac programs use one set of function
calls, and GNUstep programs use a different set (I mentioned the
lameness part, right?).

Stan