Re: Unwind-Protect and Jumping into the Abyss

[R James Noble <kjx@comp.vuw.ac.nz>]

 description of proposed _UnwindProtect: and _ContinueUnwind

> this primitive pair would probably cover
> most cases and would be relatively simple to implement as long as
> super-high performance is not the main goal.

Performance - this is _research_ :-). Any performance is preferable to
none, and I think these should do the trick.  Presumably the
_ContinueUnwind call could be hidden in the Self wrapper for
unwindProtect:

>> "NLRs across process cause the process to terminate"
> Gee, I though nobody would ever discover this :-)

It was only a matter of time :-).  Actually, I think the current
behaviour is quite sensible. It allows me to fake non-lifo blocks by
creating them then permantly suspending the process.  But an NLR
causing another process to resume seems rather strange.

> We've been planning to put unwinf protect into the system for a while

As ever, this would make my life a lot easier. 

James