Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!uflorida!gatech!ulysses!gsf
From: gsf@ulysses.homer.nj.att.com (Glenn Fowler[eww])
Newsgroups: comp.lang.c++
Subject: Re: Including header files minimally.
Summary: alternative requires more work
Message-ID: <10873@ulysses.homer.nj.att.com>
Date: 19 Nov 88 14:56:46 GMT
References: <3561@pt.cs.cmu.edu> <7860@nsc.nsc.com> <3614@pt.cs.cmu.edu>
Organization: AT&T Bell Laboratories, Murray Hill
Lines: 22

In article <3614@pt.cs.cmu.edu>, dld@f.gp.cs.cmu.edu (David Detlefs) writes:
> ...
> performance.  I don't think it is "semantically muddy."  To explain it
> again: you include a file.  If this file contains no #if-like
> constructs, it will generate the same code every time it is included,
> ...

this breaks with the following simple example:
x.h:
	extern int	VARIABLE;
tst.c:
	#include "x.h"
	#define VARIABLE	abc
	#include "x.h"

a proper implementation would have to keep a list of all identifiers
referenced within a header to determine if a repeated include would
produce different results -- the problem is compounded by nested
includes
-- 
Glenn Fowler    (201)-582-2195    AT&T Bell Laboratories, Murray Hill, NJ
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