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From: Florian Weimer <fw@deneb.enyo.de>
Newsgroups: comp.lang.ada
Subject: Re: Implementing C/C++ style #include...
Date: 27 Mar 2001 00:34:07 +0200
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Date: 2001-03-27T00:34:07+02:00
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Stephen Leake <stephen.a.leake.1@gsfc.nasa.gov> writes:

> And anyway, what is the alternative for Linux? I guess structuring it
> so the number of configurations is actually linear with the number of
> targets, but is that really possible?

They try to isolate the configuration-specific code.  Once there was a
rule, 'no #ifdefs in actual code', but I don't know if it still
followed.  OTOH, it doesn't matter much if some configurations do not
compile.  The fix is pretty straightforward most of the time (even if
it breaks other configurations), and the usual configurations are
tested most, of course, so the probability they work is quite high.

Well, my experiences with the C preprocessor in much smaller projects
are quite bad as well.  I'm maintaining a fork of OpenSSH which adds
additional control over port forwarding (we use OpenSSH to implement
a poor man's VPN at the university because no other protocol/vendor
supports all the platforms we need), and the upstream authors use
#ifdefs in actual code.  Adding a few extra parameters to some
routines is quite annoying because of procedure calls hidden behind an
#ifdef.  For the next patching frenzy, I'm warned, but I'm convinced
as well that the C preprocessor is the source of major maintenance
headaches.