Path: utzoo!telly!ddsw1!mcdchg!rutgers!mailrus!bbn!rochester!pt.cs.cmu.edu!k.gp.cs.cmu.edu!jgm
From: jgm@k.gp.cs.cmu.edu (John Myers)
Newsgroups: gnu.gcc
Subject: Re: left-hand side cast
Message-ID: <3591@pt.cs.cmu.edu>
Date: 16 Nov 88 17:41:21 GMT
References: <2100@kalliope.rice.edu>
Distribution: gnu
Organization: Carnegie-Mellon University, CS/RI
Lines: 31

"Casts as lvalues" is the one extension that I seriously object to.
The semantics are not obvious (I had to read the description in the
manual three times before I understood what was going on) and are
certainly not what the people who have asked for lvalue casts in
comp.lang.c were asking (which is good--they generally didn't know
what they were talking about anyway.)

The extension adds no power to the language, given the typeof
operator.

	(int)a = b

is the same as:

	(int) (a = (typeof a) (int) b)

After having looked at a piece of code that used this extension and
had also #ifdef's for compilers without this extension, I must say
that the traditional code is more readable.

(If anyone is interested, the other extension that I object to, but
not quite so strongly is "Arithmetic on void-pointers and function
pointers".  If someone is manipulating byte-sized quantities, they
should make it obvious by casting the pointers to char and back.  I'd
rather have the compiler yell at me when I try to manipulate a void
pointer--those buggers are SUPPOSED to be opaque.)

-- 
_.John G. Myers		Internet: John.Myers@cs.cmu.edu
			LoseNet:  ...!seismo!inhp4!wiscvm.wisc.edu!give!up
"The world is full of bozos.  Some of them even have PhD's in Computer Science"
--