Re: PATCH: Merge objc-improvements-branch to mainline

[Ziemowit Laski <zlaski at apple dot com>]

On Wednesday, Sep 24, 2003, at 16:55 US/Pacific, Nicolas Roard wrote:

> On 2003-09-24 18:24:44 +0000 Stan Shebs <shebs@apple.com> wrote:
>
> > This has been one of the most heavily-requested features for ObjC. 
> > While
> > it's true that it's syntactic sugar, so is for(), and yet few suggest
> > that it should be removed from C. For that matter, many programmers
> > contend that ObjC and C++ are unnecessary syntactic sugar too... The
> > rationale for adding exception handling, aside from the incessant user
> > requests, is that it is hard to get right manually, plus the manual
> > solution involves fooling around with explicit flow control in the 
> > form
> > of setjmp/longjmp, which you really want to hide whenever possible.
>
> What I don't understand, is that we _already_ have an exception system,
> so what was those requests about ?
> If NS_DURING/NS_HANDLER names scared programmers, well, we could
> define them as @try ... @catch :-)
> But I don't see what's so interesting with the new exception system, 
> apart
> to bring some incompatibilities ...
> Someone could explain it to me ?

See previous e-mails from Stan and myself. :-)

Which reminds me, I did forget to mention yet 2 more benefits:
- The exception system will automatically mark variables volatile as 
needed, so that they do not get clobbered by the _setjmp/_longjmp 
interaction.
- If an exception is not handled by any of your @catch clauses, it is 
automatically propagated up the call chain

All in all, it makes exceptions in ObjC much more accessible to those 
coming from C++ or Java.

--Zem
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Ziemowit Laski                 1 Infinite Loop, MS 301-2K
Mac OS X Compiler Group        Cupertino, CA USA  95014-2083
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