[R-SIG-Mac]OS X and OS 9

[Jan de Leeuw]

Some additional info.

I agree that Carbon is  not a problem, and is becoming even less of a  
problem over time, because Carbon
and Cocoa are becoming more integrated. Apple gives reasons to prefer  
Cocoa (formerly NeXTStep) over Carbon
(formerly MacOS Toolbox), but they are mostly convenience and  
aesthetics. If you have a large codebase,
use Carbon and C, if you start from scratch, use Cocoa and Objective-C.

Ken does not emphasize that dyld/Mach-O is the only native runtime and  
that the CFM/PEF runtime is layered
on top of dyld/Mach-O, so one needs to go through an additional layer  
of software (similar to how 68K emulation
was layered on top of the PPC runtime). CFM apps cannot directly call  
functions in dyld-based libraries, another
bridge is needed for that. This is important, because all frameworks  
and *nix libraries in OS X are dyld-based,
even the Carbon frameworks.

What Mozilla is doing is making the CFM version a "port", which means  
they are not maintaining it themselves
any more, they will switch to Mach-O (still using Carbon).

I should also clarify that Apple will continue to make machines that  
boot into OS 9 available for 1) education and
2) for high-end graphic/typographic work (because of Quark). Also, it  
will be possible to boot into OS 9 from a
CD, and Classic will remain available.

On Tuesday, December 17, 2002, at 04:14 PM, Ken Beath wrote:

> One point that needs to be clarified is that Carbon itself is not a  
> problem. Apple originally saw Carbon as a transition technology but  
> that seems to have ended after Adobe, Microsoft et al told them it  
> that they wouldn't convert their code to run using anything else. Now  
> it is just one option for constructing applications.
>
> The important factor is Mach-O vs CFM. These determine how a  
> executable is constructed and how it is loaded into memory and runs.  
> CFM is the method used on PowerPC prior to MacOS X.  For MacOS X you  
> can compile carbon to either Mach-O or CFM. Only the CFM runs on  
> earlier OS. The Mach-O apps allow a lot more. You can access some  
> newer features of Carbon and use Cocoa and Unix routines.  You can for  
> example use Carbon for the interface, Unix for the file calls and  
> whatever bits of Cocoa appeal.
>
> In CodeWarrior the IDE does most of the work of changing a CFM app to  
> Mach-O. Only apps that do things like loading in code and other  
> similar things or use CFM libraries need changes. (I should add that I  
> haven't tried this myself)
>
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===
Jan de Leeuw; Professor and Chair, UCLA Department of Statistics;
Editor: Journal of Multivariate Analysis, Journal of Statistical  
Software
US mail: 9432 Boelter Hall, Box 951554, Los Angeles, CA 90095-1554
phone (310)-825-9550;  fax (310)-206-5658;  email: deleeuw@stat.ucla.edu
homepage: http://gifi.stat.ucla.edu
   
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