The State of Exceptions

Michael S. Klein mklein at
Sat Oct 17 01:23:59 UTC 1998

The trouble with viewing non-local returns as continuations is that
when contexts return, their sender fields get niled out. I know that
this makes sense for a stack-based hybrid approach to contexts, but
I was wondering if there were deeper reasons for this.

-- Mike

mklein at

On Fri, 16 Oct 1998, Ralph E. Johnson wrote:

> At 9:04 PM 10/12/98, Sheldon Nicholl wrote:
> >I really feel like I'm going out on a limb by saying this, but I think
> >Smalltalk would be a better language if non-local returns were
> >removed entirely. They cause trouble all across the board, from
> >the Debugger to the VM to beginning Smalltalkers trying to learn
> >the language.
> >
> >The clean solution is continuations. Otherwise raise an exception.
> But non-local returns ARE continuations.  I don't get it.
> I think that non-local returns are just fine.  VisualWorks implements
> them (with exception-handling) fine, Squeak just needs to follow suit.
> Sure, they are a problem with beginning Smalltalkers, but no more than
> pure continuations would be.
> -Ralph

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