Path: utzoo!attcan!uunet!mailrus!tut.cis.ohio-state.edu!snorkelwacker!spdcc!ima!haddock!karl
From: karl@haddock.ima.isc.com (Karl Heuer)
Newsgroups: comp.lang.c
Subject: Re: extern
Message-ID: <17037@haddock.ima.isc.com>
Date: 6 Jul 90 20:14:23 GMT
References: <111254@linus.mitre.org> <910@bjcong.bj.co.uk> <277@taumet.com> <16994@haddock.ima.isc.com> <1990Jul5.044045.1534@acc.stolaf.edu>
Reply-To: karl@haddock.ima.isc.com (Karl Heuer)
Organization: Interactive Systems, Cambridge, MA 02138-5302
Lines: 23

In article <1990Jul5.044045.1534@acc.stolaf.edu> hannum@haydn.psu.edu (Charles Hannum) writes:
>In article <16994@haddock.ima.isc.com> karl@haddock.ima.isc.com (Karl Heuer) writes:
>>[Rather than the `#define EXTERN' hack, many of us prefer to use `extern' in
>>the header and a defining instance in one source file, which also includes
>>the same header.  This] is also completely portable, doesn't require
>>preprocessor games, and allows the objects to have initializers ... [and]
>>you can't get them out of sync.

>Some of us also find your method grotesque, because we have to alter the
>definition in *two* places rather than one if we change it.

If you change something as fundamental as the type of an object, you probably
have to change every reference in *every* source file.  If it's sufficiently
abstract that you don't, then use a typedef, and change only the header.

>"... preprocessor games, ..."?  It's not a game.  It's a perfectly ligitimate
>use of the C preprocessor.  If we weren't supposed to use it, it wouldn't be
>included (based C's minimalist philosophy).

This argument applies equally well to all sorts of preprocessor abuse, all
strictly legal C.  Sorry, I don't buy it.

Karl W. Z. Heuer (karl@kelp.ima.isc.com or ima!kelp!karl), The Walking Lint