Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!ncar!oddjob!nucsrl!gore
From: gore@eecs.nwu.edu (Jacob Gore)
Newsgroups: comp.lang.c++
Subject: Re: Proposal for Exceptions for C++
Message-ID: <8180009@eecs.nwu.edu>
Date: 1 Apr 88 02:04:41 GMT
References: <8180006@eecs.nwu.edu>
Organization: Northwestern U, Evanston IL, USA
Lines: 28

/ comp.lang.c++ / lgy@pupthy2.PRINCETON.EDU (Larry Yaffe) / Mar 31, 1988 /
>In article <17935@watmath.waterloo.edu> pabuhr@watmsg.waterloo.edu (Peter A. Buhr) writes:
>>Now, you see, I don't consider this situation as an exception. PL/I
>>handles this using ON CONDITIONS, which are not exception, but
>>dynamically bound procedure calls.
>
>[...] To me, an "exception" indicates
>that something exceptional happened, possibly needing some intervention
>(a handler), but not necessarily something "disasterous" (i.e., requiring
>major alteration in the flow of control).  From the language design
>viewpoint, it seems arbitrary and unpleasant to force a distinction
>between "dynamically bound procedure calls" - possibly triggered by
>hardware traps - and "real" exceptions.

Actually, I think it's a very nice distinction.  There are languages where one
can make heavy use of procedures activated on certain conditions -- for
example, when a variable's value changes.  Their activation not only indicates
nothing disasterous, but nothing exceptional, either.

I am having some trouble classifying your example (counting overflows).
Overflows are USUALLY associated with exceptional situation.  However, if you
expect that overflows are not unlikely to happen -- if you didn't, why would
you want to count them? -- then I would not consider overflows exceptional.

(I'm not sure what all this has to do with dynamic binding of procedure calls,
but that's another story...)

Jacob Gore				Gore@EECS.NWU.Edu
Northwestern Univ., EECS Dept.		{oddjob,gargoyle,ihnp4}!nucsrl!gore