Path: utzoo!utgpu!water!watmath!clyde!att-cb!att-ih!pacbell!ptsfa!lll-tis!mordor!lll-lcc!pyramid!cbmvax!snark!eric
From: eric@snark.UUCP (Eric S. Raymond)
Newsgroups: comp.lang.c++
Subject: Re: Proposal for Exceptions for C++
Summary: Your exception syntax considered clunky
Message-ID: <22526909:25d6@snark.UUCP>
Date: 31 Mar 88 15:42:50 GMT
Organization: Thyrsus Enterprises, Malvern PA 19355
Lines: 31
Discussion: <2495@bsu-cs.UUCP> <4194@ihlpf.ATT.COM>

In article <8180006@eecs.nwu.edu>, morrison@eecs.nwu.edu (Vance Morrison) writes:
>PROPOSAL: [for exception-handling in C]

I like the basic idea of a C analogue of LISP throw/catch, but:

	1) I'm not clear how this offers more capability than setjmp/longjmp.

	2) I think your catch syntax is un-C-like; no other construct in
	   the language makes that kind of link between adjacent statements.

I think that making 'catch' an if-like construct would fit C better; i.e
instead of

>		i = j/k; catch { printf("divide by zero error\n"); }

I suggest

	catch { i = j / k; } do { printf("divide by zero error\n"); }

I think this is easier to read, and resolves in a more elegant way the
syntactic difficulties you've noted.

On the positive side, I do believe (from my LISP experience) that this is a
suitable 'most primitive' exception-handling mechanism for environments with
only a single control thread (for multiple-thread environments you need to
support *named* exceptions, because a common global exception-type variable
could get fandangoed on).
-- 
      Eric S. Raymond                     (the mad mastermind of TMN-Netnews)
      UUCP: {{uunet,rutgers,ihnp4}!cbmvax,rutgers!vu-vlsi}!snark!eric
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