Path: utzoo!attcan!uunet!lll-winken!lll-ncis!helios.ee.lbl.gov!nosc!ucsd!rutgers!att!whuts!homxb!houxs!daw
From: daw@houxs.ATT.COM (David Wolverton)
Newsgroups: comp.lang.c
Subject: Re: C Style
Summary: compile-time effect
Message-ID: <1118@houxs.ATT.COM>
Date: 12 Jan 89 14:24:02 GMT
References: <2688@ficc.uu.net> <9336@smoke.BRL.MIL>
Organization: AT&T Bell Labs, Holmdel, NJ
Lines: 18

In article <9336@smoke.BRL.MIL>, gwyn@smoke.BRL.MIL (Doug Gwyn ) writes:
> 
> 	2.  If the header just defines macros and structures,
> 	and declares types of external objects and functions,
> 	then you don't need to ensure one-time actions, because
> 	such actions can be repeated safely.  Typedefs are the main
> 	things that need to be protected against a second invocation.

You may still want to use the lockout even when it is safe to include
the header more than once.  My gut-level is that your compile time
would be improved if you have long headers WITH lockouts, because then
the preprocessor is effectively the only part of the compiler that must
process/scan that part of the incoming source.  Without lockouts,
the compiler must parse that stuff, do bookkeeping, etc. which adds
to the compile time.

Dave Wolverton
daw@houxs.att.com