Path: utzoo!utgpu!water!watmath!clyde!att-cb!att-ih!pacbell!ames!ubvax!pyramid!prls!philabs!pwa-b!mmintl!franka
From: franka@mmintl.UUCP (Frank Adams)
Newsgroups: comp.lang.c
Subject: Re: == vs =
Message-ID: <2794@mmintl.UUCP>
Date: 29 Mar 88 19:40:58 GMT
References: <11216@brl-adm.ARPA> <2111@chinet.UUCP> <4403@garfield.UUCP> <931@micomvax.UUCP> <1011@mcgill-vision.UUCP> <956@micomvax.UUCP> <1390@eneevax.UUCP>
Reply-To: franka@mmintl.UUCP (Frank Adams)
Organization: Ashton-Tate Corporation, East Hartford Development Center
Lines: 38

In article <1390@eneevax.UUCP> noise@eneevax.umd.edu.UUCP (Johnson Noise) writes:
>	I'm curious, is there anyone other than Ray Dunn that does
>not like = and == ?

Let me restate my opinion.

I want to keep = and == with almost exactly the same syntax as they have
now.  The only difference is that = does not have as its value the result of
the assignment; instead its value is void.  A new operator, perhaps :=,
should be introduced, which has exactly the definition that = has now.
(However, I would expect a good compiler to complain if the result of the
operator is not used, something which cannot (reasonably) be done with the
current syntax.

This means:

(1) We still have the simple, one character operator for the common case.
This *is* important.

(2) If one miswrites = when one means ==, one gets an error message.

(3) The proposal cleans up the semantics by eliminating the category of
expressions with a non-void type whose value is commonly ignored.  (Mostly
-- there still may be functions returning values which are commonly
ignored.) This means that a strict compiler can check that a value is used
if and only if it is not void.  (Casting to void is, of course, permitted.)

This could actually be introduced into C over a period of years.  The first
step is to introduce the new assignment operator, continuing to support use
of the result of an = assignment as an obsolete feature.  At some later
point, this could be phased out.

In any event, I would like to see something like this in D (if that ever
happens).
-- 

Frank Adams                           ihnp4!philabs!pwa-b!mmintl!franka
Ashton-Tate          52 Oakland Ave North         E. Hartford, CT 06108