Path: utzoo!mnetor!uunet!mcvax!guido
From: guido@cwi.nl (Guido van Rossum)
Newsgroups: comp.lang.c++
Subject: Re: C++ releases from AT&T?
Message-ID: <257@piring.cwi.nl>
Date: 31 Mar 88 08:52:29 GMT
References: <254@piring.cwi.nl> <1517@dataio.Data-IO.COM>
Reply-To: guido@cwi.nl (Guido van Rossum)
Organization: The Royal Society for Prevention of Cruelty to Amoebae
Lines: 37

I wrote:
<anybody care to comment on the question of what happens to code after
<"if (constant-expression-evaluating-to-zero) ..." ?

and bright@Data-IO.COM (Walter Bright) replies:

>I also believe this is an implementation issue, not a language issue.

This is the crux.  I want it to be a language issue, so I can replace
90% of the occurrences of
	
	#ifdef DEBUG
		printf("We did it!!!!!!!!!!\n");
	#endif

by

		if (debug) printf("Did it...\n");

which is much less disturbing for the reader of the code.
It can be controlled by a variable or a constant, e.g.:

	#ifdef NDEBUG
	const debug = 0;
	#else
	int debug; /* Set by -D command line flag */
	#endif

However, I need some reassurance that turning on NDEBUG will actually
remove all these debug lines from my code.  A wording similar to that
used for the descriuption of 'inline' would be fine: the intention is
clear, and compiler writers should attempt to honor it if reasonably
possible.

--
Guido van Rossum, Centre for Mathematics and Computer Science (CWI), Amsterdam
guido@cwi.nl or mcvax!guido or (from ARPAnet) guido%cwi.nl@uunet.uu.net