Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!umich!samsung!usc!snorkelwacker!spdcc!ima!haddock!karl
From: karl@haddock.ima.isc.com (Karl Heuer)
Newsgroups: comp.std.c
Subject: dollar signs in identifiers (was: warning: '/*' within comment)
Message-ID: <16812@haddock.ima.isc.com>
Date: 7 Jun 90 01:51:39 GMT
References: <1990Jun1.200433.6919@druid.uucp> <AaOZGd_00as98coVU9@andrew.cmu.edu> <16786@haddock.ima.isc.com> <371@necssd.NEC.COM>
Reply-To: karl@haddock.ima.isc.com (Karl Heuer)
Organization: Interactive Systems, Cambridge, MA 02138-5302
Lines: 32

In article <371@necssd.NEC.COM> harrison@necssd.NEC.COM (Mark Harrison) writes:
>	#if VMS
>	extern char * x$something;  /* however it's done */
>	#endif

As noted in the previous article, the quote is shielded by the comment.  That
`$' is a bit trickier, though.  It lexes into a single pp-token, which is
excluded along with its neighbors on a non-VMS system (assuming the symbol VMS
has the obvious meaning); I presume that if there's ever an ANSI compiler on
VMS, it will issue a trivial diagnostic, and, since the presence of the
invalid token throws us into the realm of Undefined Behavior, the compiler
will conveniently choose to define this situation to mean `glue these together
into a single token'.

Or more likely, such a compiler will support something like `#pragma enable
extended_identifiers', since that would allow the expected behavior for
macros, too.  (The Standard requires that the strictly conforming program
	#include <stdio.h>
	#define foo$bar /* define foo to be dollar-bar */
	#ifdef foo
	int main(void) { printf("yes\n"); return 0; }
	#else
	int main(void) { printf("no\n"); return 0; }
	#endif
must print "yes"; normal VMS behavior would be to treat `foo$bar' as a single
token and print "no".)

Personally, I think the treatment of unexpected characters should have been
implementation-defined.  But hey, DEC and Apollo both had representatives on
the Committee, and if they're satisfied, who am I to complain?

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