From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 101deb,3488d9e5d292649f X-Google-Attributes: gid101deb,public X-Google-Thread: 103376,e6a2e4a4c0d7d8a6 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2003-02-21 14:14:31 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!sn-xit-03!sn-xit-06!sn-post-01!supernews.com!corp.supernews.com!not-for-mail From: "Shmuel (Seymour J.) Metz" Newsgroups: comp.lang.pl1,comp.lang.ada Subject: Re: status of PL/I as a viable language Date: Fri, 21 Feb 2003 15:26:06 -0500 Organization: Atid/2 Message-ID: <3e568b5e$7$fuzhry+tra$mr2ice@news.patriot.net> References: <3E554AF4.C8F0EF2E@yahoo.com> <819A9E0CA1094B88.6E582670555DCA33.F06C4B2BCD076570@lp.airnews.net> Mail-Copies-To: nobody X-Cise: tanbanso@iinet.net.au X-CompuServe-Customer: Yes X-Coriate: admin@interspeed.co.nz X-Ecrate: tanandtanlawyers.com X-Punge: Micro$oft X-Sanguinate: themvsguy@email.com X-Terminate: SPA(GIS) X-Tinguish: Mark Griffith X-Treme: C&C,DWS X-Newsreader: MR/2 Internet Cruiser Edition for OS/2 v2.31a/31 X-Complaints-To: abuse@supernews.com Xref: archiver1.google.com comp.lang.pl1:4412 comp.lang.ada:34399 Date: 2003-02-21T15:26:06-05:00 List-Id: In <819A9E0CA1094B88.6E582670555DCA33.F06C4B2BCD076570@lp.airnews.net>, on 02/20/2003 at 05:30 PM, "John R. Strohm" said: >On just about every machine I've ever dealt with, dereferencing a >null pointer throws a hardware trap. If the compiler takes the easy route and represents a null pointer as 0, there won't be a hardware trap on, e.g., a system running MVS[1] or VM[2]. >Catching a hardware trap and recovering from it is almost always >MUCH more expensive than checking a pointer for null. Why do you care? Explicitly testing is always much more expensive when the pointer is valid, which is much more common, so in aggregate it is more expensive than using an invalid address for null and letting the hardware catch it. Your argument only holds water if the path for handling an exception is itself time critical. [1] Of any vintage from OS/VS2 R2 through z/OS. [2] Of any vintage from VMF/370 through z/VM. -- Shmuel (Seymour J.) Metz, SysProg and JOAT Any unsolicited commercial junk E-mail will be subject to legal action. I reserve the right to publicly post or ridicule any abusive E-mail. I mangled my E-mail address to foil automated spammers; reply to domain Patriot dot net user shmuel+news to contact me. Do not reply to spamtrap@library.lspace.org