Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!gem.mps.ohio-state.edu!samsung!ginosko!aplcen!haven!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.lang.c
Subject: Re: A solution to the multiple inclusion problem
Message-ID: <11422@smoke.BRL.MIL>
Date: 27 Oct 89 17:35:39 GMT
References: <946@friar-taac.UUCP> <8956@goofy.megatest.UUCP>
Reply-To: gwyn@brl.arpa (Doug Gwyn)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 16

In article <8956@goofy.megatest.UUCP> djones@megatest.UUCP (Dave Jones) writes:
-))In article <14240@well.UUCP) nagle@well.UUCP (John Nagle) writes:
-)))	#ifndef XXX
-)))	#define XXX
-)))	...content...
-)))	#endif
-... do it this way...
-	#ifndef XXX
-	...content...
-	#define XXX
-	#endif

I recommend just the opposite.  If the body of the header #includes
itself recursively (which is a very useful thing to permit), then
the idempotency lock doesn't work right unless you set it before
the nested #inclusion.