Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!pasteur!helios.ee.lbl.gov!ncis.tis.llnl.gov!lll-winken!uunet!mcvax!hp4nl!botter!star.cs.vu.nl!ast
From: ast@cs.vu.nl (Andy Tanenbaum)
Newsgroups: comp.os.minix
Subject: Re: Re^2: Future of Minix
Message-ID: <2897@ast.cs.vu.nl>
Date: 17 Jul 89 19:43:18 GMT
References: <19654@louie.udel.EDU> <2885@ast.cs.vu.nl> <465@medusa.informatik.uni-erlangen.de>
Reply-To: ast@cs.vu.nl (Andy Tanenbaum)
Organization: VU Informatica, Amsterdam
Lines: 29

In article <465@medusa.informatik.uni-erlangen.de> dkhusema@immd4.informatik.uni-erlangen.de (Dirk Husemann) writes:
>	How about using the #ifdef-#endif constructs at a different place
>E.g.
>#ifdef DEBUG
>#define DB2(format, arg1, arg2)		/* something to print the args accor-
>#define DB3(format, arg1, arg2, arg3)	/* ditto */
>#else /* DEBUG */

I agree that something along those lines would be an improvement.
Also, call them DEBUG2 and DEBUG3 instead of DB2 and DB3.  

Even better is to use assertions.  Things like:

ASSERT(x < y && z != 0);

could be handled by

#ifdef DEBUG
#define ASSERT(predicate) if (!(predicate)) printf("Assertion error ...\n");
#else
#define ASSERT(predicate)	/* nothing */
#endif

I think assertions have utility as comments even when no code is generated.
There is already a file assert.h in V1.3.  The only thing wrong with it
is that instead of #ifdef DEBUG, it says #ifdef NDEBUG.  
I think NDEBUG is 10x harder to understand.

Andy Tanenbaum (ast@cs.vu.nl)