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From: davidra@batcomputer.tn.cornell.edu (David A. Rabson)
Newsgroups: comp.std.c,comp.lang.c
Subject: Re: Variable length arg lists for macros
Message-ID: <6191@batcomputer.tn.cornell.edu>
Date: 1 Sep 88 23:48:41 GMT
References: <438@ucsvc.unimelb.edu.au> <1036@cbnews.ATT.COM> <429@thirdi.UUCP>
Reply-To: davidra@tcgould.tn.cornell.edu (David A. Rabson)
Organization: Cornell Theory Center, Cornell University, Ithaca NY
Lines: 27

(Summary: people complain about lack of variable-length arg lists for
 macros.  Standards people try to cover themselves.  Other people point
 out that (( ... )) often works almost as well as variable-length arg list.)

There is another way to fake out at least some preprocessors.  I find the
following useful in header files.  The header file is included in several
code files only one of which defines GLOBALS.

#undef INIT
#undef COMMA
#define COMMA ,

#ifdef GLOBALS
#define INIT(x) =x
#else
#define INIT(x) /*nop*/
#endif

extern int x[2] INIT({1 COMMA 2});


Since the (( )) and COMMA kludges cover all the cases where I might have
wanted variable-length argument lists in cpp macros, I have to agree
that the extension would be unnecessary

				David Rabson
				Laboratory of Atomic and Solid State Physics