Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!decwrl!decvax!ima!haddock!karl
From: karl@haddock.ima.isc.com (Karl Heuer)
Newsgroups: comp.lang.c
Subject: Re: %p and different pointer representations
Message-ID: <11915@haddock.ima.isc.com>
Date: 1 Mar 89 19:14:51 GMT
References: <9382@bloom-beacon.MIT.EDU> <234@mstan.Morgan.COM> <16112@mimsy.UUCP> <592@jhereg.Jhereg.MN.ORG> <16120@mimsy.UUCP> <597@jhereg.Jhereg.MN.ORG>
Reply-To: karl@haddock.ima.isc.com (Karl Heuer)
Organization: Interactive Systems, Boston
Lines: 12

In article <597@jhereg.Jhereg.MN.ORG> mark@jhereg.MN.ORG (Mark H. Colburn) writes:
>What it means, is that there is no portable way to pass an arbitrary pointer
>to a function or store one in a data structure.

Any function-pointer object may be cast to any other function-pointer type and
back without change; hence any such type (e.g. `void (*)(void)') may be used
as a generic function-pointer type.  Therefore, a completely generic pointer
type (to function or data) is `union {void (*)(void); void *}', though I can't
think of any practical use for such a thing.  (The (nonportable) uses I can
come up with are better served by a cast rather than a union.)

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