Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!husc6!cmcl2!brl-adm!adm!dsill@nswc-oas.arpa From: dsill@nswc-oas.arpa (Dave Sill) Newsgroups: comp.lang.c Subject: Re: Noalias trivia question Message-ID: <16244@brl-adm.ARPA> Date: 21 Jun 88 15:37:05 GMT Sender: news@brl-adm.ARPA Lines: 42 Peter J Desnoyerswrites: >I realize that you may be able to come up with an >approximation that is computable, but note that [you] must never fail to >detect aliasing when it exists. Yes, this is my point exactly. And it's very similar to what Chris has been saying about `volatile'. I'd rather take a slight performance hit to avoid a zillion modifiers like `volatile' and `noalias' (who knows what will be next?) that can introduce subtle bugs and complicate the language. I'm willing to wait until we have compilers that can tell when aliasing is not possible or when volatility is not possible, and optimize accordingly. >I merely mean to point out that >most programmers accomplish, through judicious foresight (and by >avoiding gruesome code which the compiler is required to accept) tasks >which the compiler must accomplish through extensive or even >impossible checking. Herein lies the difference in our opinions. My philosophy is that anything that can be done by the compiler to make the programmer's job easier or anything that can be done better by the compiler should be done by the compiler. Why require all programmers to be concerned with aliasing/volatility/etc when, let's face it, they are so likely to either not bother with it, or, if they do, to do it wrong? Probably better than 90% of all C programmers don't even have a good grasp on the simple pointers of K&R C. I've seen too many people do "char *p; ... strcpy (p, foo);", without pointing p at something reasonable first, to have any degree of confidence in their use of something like `noalias'. Should we pander to the least common denominator? No, but neither should we introduce keywords aimed at the very small number of C programmers that would actually use them correctly, especially when their misuse by the masses would be inevitable. ========= The opinions expressed above are mine. "We must remove the TV-induced stupor that lies like a fog across the land." -- Ted Nelson