Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!zaphod.mps.ohio-state.edu!rpi!sci.ccny.cuny.edu!phri!marob!cowan
From: cowan@marob.masa.com (John Cowan)
Newsgroups: comp.std.c++
Subject: Re: "->" == "." proposal
Message-ID: <27304544.3658@marob.masa.com>
Date: 1 Nov 90 15:54:43 GMT
References: <52390002@hpcupt1.cup.hp.com>
Organization: The Logical Language Group, Inc.
Lines: 36

In article <52390002@hpcupt1.cup.hp.com>,
	jamiller@hpcupt1.cup.hp.com (Jim Miller) writes:
>
>I'd like suggest a modification for C++:
>    Make "." and "->" equivalent.

I would strongly support the above proposal with one change.  Currently,
-> can be overloaded in classes but "." cannot.  So leave -> alone, and
make "." an operator that accepts either a class/struct or a pointer to
one, with automatic dereferencing of the pointer.   This has no impact
on existing code, and does not change the compiler much either -- instead
of reporting an error, it just installs a dereference coercion.

It seems to me that C would have supported this feature from day one, but for
the weak type-checking of the C compiler, where the left argument to -> could be
anything whatever, even an int (interpreted as a raw machine address), and
the right argument could be any structure tag, even one belonging to a different
structure.  This misfeature has long been removed from all sane compilers,
and is explicitly forbidden by the ANSI C standard.

Implicit dereferencing does exist elsewhere in the C language: a pointer
to function is implicitly dereferenced when an attempt is made to call
using it, so that (*pfi)() and pfi() mean the same thing, where pfi
is of type "pointer to function returning int".

Also, though I hate to mention the P-word around here,
in Mesa (Xerox's extended dialect of Pascal) this overloading of "."
is also done.  (Standard Pascal has no analogue of -> but requires explicit
dereferencing with ^, Pascal's version of unary *.)

Would a knowledgeable person tell me by e-mail how to get this idea before
the ANSI committee?  I know the answer is "send in a recommendation";
what I want is address, format of request, etc.
-- 
cowan@marob.masa.com			(aka ...!hombre!marob!cowan)
			e'osai ko sarji la lojban