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From: dwp@willett.pgh.pa.us (Doug Philips)
Newsgroups: comp.lang.forth
Subject: Re: ANS TC Magnet for Cont. Ref. Set
Message-ID: <2312.UUL1.3#5129@willett.pgh.pa.us>
Date: 8 Feb 91 12:17:46 GMT
References: <2756383@harvee.UUCP>
Organization: (n.) to be organized.  But that's not important right now.
Lines: 32

In article <2756383@harvee.UUCP>,
	esj@harvee.UUCP (Eric S Johansson) writes:
> 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.  

Personally, when I consider at what should or shouldn't be in the standard,
preference should be given to putting into a core wordset the lowest
level words that will *portably* let you write code to do X.  Then, if
there is a need (real or perceived, but I don't what to get into that here)
for some "common tools" like CASE, that can be in an extended wordset.
This is one reason I like Wil Baden's control structures, they are at the
lowest *portable* level, and give the necessary flexibility.  The issue of
the CASE statement I'm more ambivalent about.  As for CATCH/THROW, I think
that we need low-level words to implement a variety of non-local control
structures (which are not as important as the local control structures).
Of course, it would be ideal if there would be one unified set of control
structure words, but I don't know if Wil has looked into that or not,
or even if it is possible.  I think Mitch's CATCH/THROW are sufficient
for that, but I'm not an expert Forth programmer.

-Doug
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