Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!ames!necntc!ima!haddock!karl
From: karl@haddock.ISC.COM (Karl Heuer)
Newsgroups: comp.lang.c
Subject: Re: A different view of volatile
Message-ID: <3642@haddock.ISC.COM>
Date: 26 Apr 88 21:01:29 GMT
References: <13074@brl-adm.ARPA> <2003@rtech.UUCP> <7996@pur-ee.UUCP>
Reply-To: karl@haddock.ima.isc.com (Karl Heuer)
Organization: Interactive Systems, Boston
Lines: 28

In article <7996@pur-ee.UUCP> hankd@pur-ee.UUCP (Hank Dietz) writes:
>Instead, why not use "register" to solve the [volatile] problem....

Currently, "break" has two (or maybe one and a half) meanings, "static" has
two meanings, and "void" has three.  I'd rather not see "register" achieve a
similar overloading, which is what I see in your proposal.

>[a register object cannot be volatile]

But the converse is false.  I use non-volatile non-register objects all the
time.

Also, your proposal breaks the rule of defaulting to the most common case.
Most programs don't need *any* volatile declarations, and of those that do,
most objects are *not* so qualified.  This is why X3J11 invented "volatile"
rather than "novolatile".

>register static double d[100];

How does the register-nonaddressibility rule interact with the automatic decay
of the array expression "d" into the pointer "&d[0]"?  You'd need to define
the rules very carefully to make this declaration useful.

>char *strcpy(char register *p, register *q;) { ... }

Minor nit: types don't propagate in a function prototype; you need "char" in
both declarations.  And no semicolon.

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