Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!rutgers!uwvax!oddjob!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.arch
Subject: Semantics (was Software Distribution)
Message-ID: <13889@mimsy.UUCP>
Date: 6 Oct 88 10:18:52 GMT
References: <634@eiger.iis.UUCP> <993@esunix.UUCP>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 26

In article <993@esunix.UUCP> bpendlet@esunix.UUCP (Bob Pendleton) writes:
>... I'm in favor of defining the
>behavior of every operator in a language on all of its operand set.

Why?

>Since NULL can be stored in a pointer, the actions of all pointer
>operators when applied to NULL should, in my opinion, be defined.

I disagree.

In particular, with regard to the more general statement, if we can
improve the performance of a language on existing architectures by
explicitly leaving certain semantics undefined, should we do so?  The
argumentam [? ablative case anyway] pro is simple: programs run X%
faster.  The argumentam con appears to be that programmers will use
the construct anyway.  So what?  Those programs are then by definition not
portable and may be considered just so many random bits: worthless.
It is up to the programmer, and the buyer of programs, to make sure
that programs in this language do not depend on undefined semantics.

Just because I can use a knife as a screwdriver does not mean that
all knives should also be screwdrivers. . . .
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris