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-Thread: a07f3367d7,fef40c7c6b003852 X-Google-Attributes: gida07f3367d7,public,usenet X-Google-NewGroupId: yes X-Google-Language: ENGLISH,ASCII-7-bit Received: by 10.180.98.234 with SMTP id el10mr101381wib.3.1348195800875; Thu, 20 Sep 2012 19:50:00 -0700 (PDT) Path: q11ni4227872wiw.1!nntp.google.com!feeder3.cambriumusenet.nl!94.232.116.13.MISMATCH!feed.xsnews.nl!border-3.ams.xsnews.nl!npeer.de.kpn-eurorings.net!npeer-ng0.de.kpn-eurorings.net!xlned.com!feeder3.xlned.com!feeder2.cambriumusenet.nl!feed.tweaknews.nl!216.40.29.245.MISMATCH!novia!border4.nntp.dca.giganews.com!border2.nntp.dca.giganews.com!border3.nntp.dca.giganews.com!border1.nntp.dca.giganews.com!nntp.giganews.com!nrc-news.nrc.ca!goblin1!goblin.stu.neva.ru!news.mixmin.net!weretis.net!feeder1.news.weretis.net!news.szaf.org!news.gnuher.de!rz.uni-karlsruhe.de!feed.news.schlund.de!schlund.de!news.online.de!not-for-mail From: Dirk Heinrichs Newsgroups: comp.lang.ada Subject: Re: Time Stamping Again. Date: Sat, 15 Sep 2012 18:12:45 +0200 Organization: Privat Message-ID: References: <7c39a531-1058-42de-9e56-f03f2b9f92dc@googlegroups.com> <50545526$0$21224$ba4acef3@reader.news.orange.fr> <1dc13f16-a869-451d-9027-cf78c162998f@googlegroups.com> NNTP-Posting-Host: pd9ff8215.dip0.t-ipconnect.de Mime-Version: 1.0 X-Trace: online.de 1347725565 21193 217.255.130.21 (15 Sep 2012 16:12:45 GMT) X-Complaints-To: abuse@einsundeins.com NNTP-Posting-Date: Sat, 15 Sep 2012 16:12:45 +0000 (UTC) User-Agent: KNode/4.9.1 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7Bit Date: 2012-09-15T18:12:45+02:00 List-Id: Austin Obyrne wrote: > To me this is more a passing curio that seems to be going unnoticed by > many users of language compilers. > > It has been put there for a purpose no doubt and I speculate on at least > one good use to which it may be put ! It's not really going unnoticed. It is a standard feature of any C/C++ compiler provided via the __TIME__ and __DATE__ macros. But in most cases, it is considered harmful. Let's think about software development in larger teams. Let's also assume that it is vital for fixing bugs to be able to exactly and verifiably reproduce past builds. So you do a release build and create checksums of your .o files. When you need to reproduce that builds a year or two later, you can again create checksums and check them against the original ones to make sure you've built exactly what the customer has. Now, when above macros have been used to record compilation time and date in your .o files, you'll always have a checksum mismatch and you can never be sure that you've built again what has been built before. So checksums are, as others have already pointed out, the far better alternative, because a checksum always stays the same for the same compilation, but a timestamp does not. Bye... Dirk -- Dirk Heinrichs Tel: +49 (0)2471 209385 | Mobil: +49 (0)176 34473913 GPG Public Key C2E467BB | Jabber: dirk.heinrichs@altum.de