Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!bu.edu!wang!harvee!esj
From: esj@harvee.UUCP (Eric S Johansson)
Newsgroups: comp.lang.forth
Subject: Re: ANS TC Magnet for Cont. Ref. Set
Message-ID: <2756383@harvee.UUCP>
Date: 28 Jan 91 23:44:30 GMT
References: <2284.UUL1.3#5129@willett.pgh.pa.us>
Organization: gators 'r us
Lines: 42
X-Version: Rodney's UUCP modules 05/09/90 V1.15

In article <2284.UUL1.3#5129@willett.pgh.pa.us> ForthNet@willett.pgh.pa.us
(ForthNet articles from GEnie) writes:
>  
> Doug Philips comments:
> 
> > What you really want here is some kind of UNWIND-PROTECTION so that
>  > if the current word is going to be blasted off the return stack
>  > by a catch, you want some code to execute first.
> 
> Indeed, I ran into this problem once, and the exception handler I designed
> (see SIGForth vol.1 no.2) had precisely this capability.
>  (It also allowed execution to continue after corrective action was taken, but
> this capability may not be as generally useful.)
> 
> Concerns like this are why I believe it's too soon to standardize
>  a Forth exception handler.
> 
> - Brad
> -----

I beg to differ.  I believe the knowledge needed for a "good"
exception handler is available from outside the forth community. 
I suggest folks check out exception handlers in eiffle, c++ smalltalk
and lisp as role models for a forth exception handlers.  I generally
find the current definition of catch/throw almost primitive enough to
permit construction of more "complete" exception handlers.  The one
thing I find missing and can't figure out how to synthesize is
something like the eiffle retry semantics.

the fact that  we can think of problems with a part of the standard is no 
reason to chuck that part.  


--- eric
--
...
^^^     eric johansson   UUCP ...!uunet!wang!harvee!esj esj@harvee.uucp
* *     a juggling fool  AT&T (617) 577-4068 (w)
 o                       HAM  ka1eec
\_/			 CSNET johansson%hydra@polaroid.com
			 or      hydra!johansson@polaroid.com
	source of the public's fear of the unknown since 1956