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From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.lang.c
Subject: Re: How big is a (??? *)
Message-ID: <6689@mimsy.UUCP>
Date: Fri, 15-May-87 01:03:53 EDT
Article-I.D.: mimsy.6689
Posted: Fri May 15 01:03:53 1987
Date-Received: Sat, 16-May-87 13:50:10 EDT
References: <737@edge.UUCP>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 28

In article <737@edge.UUCP> doug@edge.UUCP (Doug Pardee) writes:
>Just that one source module knows the description of that struct.  To
>the "outside world", each object is known only by a handle, which is
>typically (here it comes, folks) a pointer to that malloc'ed struct.
... 
>Unfortunately, as we've seen, that means that the outside world doesn't
>even know how big the pointer is.

This is the sort of problem the (void *) type in the dpANS is intended
to solve.  For now, I have been using (char *), or in some situations,
(caddr_t), which is really just an alias for (char *) after all.  If
you want to be maximally paranoid, use a header file:

	#ifdef dpANS_conformant_compiler_flag
	typedef void *handle;
	#else
	typedef char *handle;
	#endif

and mark this file `system dependent'.

(Incidentally, a `handle' usually refers to a pointer to a pointer,
the double indirection allowing space compaction of large objects,
or even allowing the faking of virtual memory on certain hardware
configurations.)
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7690)
Domain:	chris@mimsy.umd.edu	Path:	seismo!mimsy!chris