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From: karl@haddock.ISC.COM (Karl Heuer)
Newsgroups: comp.lang.c
Subject: Re: Some questions about ANSI C
Message-ID: <936@haddock.ISC.COM>
Date: Thu, 13-Aug-87 13:08:13 EDT
Article-I.D.: haddock.936
Posted: Thu Aug 13 13:08:13 1987
Date-Received: Sat, 15-Aug-87 09:26:39 EDT
References: <497@houxs.UUCP> <165600007@uiucdcsb> <6265@brl-smoke.ARPA>
Reply-To: karl@haddock.ima.isc.com (Karl Heuer)
Organization: Interactive Systems, Boston
Lines: 33

In article <6265@brl-smoke.ARPA> gwyn@brl.arpa (Doug Gwyn) writes:
>[Hex escapes, \xNNNN, may be arbitrarily long; thus a sequence like ESC B
>cannot be written "\x1bB".  Use "\x1b" "B",] or else you can write it using
>an octal constant.

I would prefer some way to forcibly terminate, perhaps "\x(1b)B".  I hope the
committee is still open to change on this issue.

>>>	Setjmp must be a macro.
>I don't have the exact wording that's going into the draft, but I think the
>problem is that the argument to setjmp() is being passed by name, which is
>possible for macros but not for functions.  (This is based on the traditional
>implementation of a jmp_buf as an array, which does not behave the same as
>other types as a typedef, coupled with the observation that some
>implementations would be better off with a non-array for their jmp_bufs.)

Can't such an implementation use a one-element array containing a struct?  Or
is there a more subtle problem here?

>>>	[agreed in principle] that parentheses should force grouping,
>>>	motion needed.
>The problem is, the public keep complaining about unary + and/or the lack of
>grouping for parens.  I think X3J11 must have decided that the "as if" rule
>still permits most ordinary regrouping ...

Arghh.  One reason I like the unary-plus idea is that it allows the programmer
to distinguish between precedence control and evaluation order.  It's a
documentation aid.  Also, I suspect that many compilers will zealously regroup
even when the as-if rule does not strictly apply; the presence of an explicit
marker -- be it unary-plus, a cast into volatile, or a re-overloading of the
keyword "break" :-) -- can be used as a warning sign.

Karl W. Z. Heuer (ima!haddock!karl or karl@haddock.isc.com), The Walking Lint