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From: minow@decvax.UUCP (Martin Minow)
Newsgroups: comp.lang.c
Subject: Re: ANS C Macro Processing
Message-ID: <173@decvax.UUCP>
Date: Wed, 21-Oct-87 23:29:52 EDT
Article-I.D.: decvax.173
Posted: Wed Oct 21 23:29:52 1987
Date-Received: Sat, 24-Oct-87 13:41:58 EDT
References: <167@sdti.UUCP>
Reply-To: minow@decvax.UUCP (Martin Minow)
Organization: Digital Eq. Corp. - Merrimack NH.
Lines: 15

In article <167@sdti.UUCP> turner%sdti@harvard.harvard.edu
(Prescott K. Turner, Jr.) notes that the Draft Ansi C Standard rules
for macro rescanning are either vague, obscure, or both.

I believe their intent can best be illustrated by an example:

#if debug > 0
#define exit(status)	(printf("Exit, status = %d\n", status), exit(status))
#endif

If macros were rescanned, the evaluation would loop forever.  Instead,
the evaluation is expanded as a "normal" function.  Hope this is clearer.

Martin Minow
decvax!minow