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=-0.3 required=5.0 tests=BAYES_00, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 X-Google-Thread: a07f3367d7,6327f05d4989a68d X-Google-Attributes: gida07f3367d7,public,usenet X-Google-NewGroupId: yes X-Google-Language: ENGLISH,ASCII-7-bit X-Received: by 10.66.75.230 with SMTP id f6mr6220088paw.25.1356837703714; Sat, 29 Dec 2012 19:21:43 -0800 (PST) Path: 6ni71714pbd.1!nntp.google.com!border1.nntp.dca.giganews.com!backlog1.nntp.ams.giganews.com!border3.nntp.ams.giganews.com!border1.nntp.ams.giganews.com!border4.nntp.ams.giganews.com!border2.nntp.ams.giganews.com!nntp.giganews.com!newsreader4.netcologne.de!news.netcologne.de!news.nobody.at!weretis.net!feeder4.news.weretis.net!news.mixmin.net!aioe.org!.POSTED!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: Press Release - Ada 2012 Language Standard Approved by ISO Date: Sun, 23 Dec 2012 09:08:53 +0100 Organization: cbb software GmbH Message-ID: <1pbg79bz92j3t$.sz41zduivjfp.dlg@40tude.net> References: <7wrdmbre6jw9.qww9l0uzj6mg.dlg@40tude.net> <14oqoq06zhlu2.tcasif3hdyhw.dlg@40tude.net> <1drh1q1ln2dfh$.a9hwlg01fjfy.dlg@40tude.net> <50d6365d$0$6577$9b4e6d93@newsspool3.arcor-online.net> Reply-To: mailbox@dmitry-kazakov.de NNTP-Posting-Host: 6/SyjDFvQ5V7ZR2+GYgbDQ.user.speranza.aioe.org Mime-Version: 1.0 X-Complaints-To: abuse@aioe.org User-Agent: 40tude_Dialog/2.0.15.1 X-Notice: Filtered by postfilter v. 0.8.2 X-Original-Bytes: 3661 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Date: 2012-12-23T09:08:53+01:00 List-Id: On Sat, 22 Dec 2012 23:38:21 +0100, Georg Bauhaus wrote: > On 22.12.12 10:02, Dmitry A. Kazakov wrote: > >>> In an ideal world, all of these "checks" will get made statically. Hopefully >>> that's coming. In mean time, it's important to get programmers used to the >>> idea of writing checks this way, so that future tools can make the checks >>> statically (there is no hope of making checks statically if they are just >>> written in natural language comments). >> >> OK, this is rather a tactical disagreement then. Ada's stance was >> conservative, not eager adding features impossible to implement properly. > > Rather, history tells that Ada has been seen by some as being just a little > less improperly adventurous than Algol 68. No, it is not same. Ada 83 compiler was difficult to build (then), especially on a small machine, but there was little doubt about practicability. >> Because somebody (Georg) could readily base his design on the faulty. > > Don't worry, my predicates tend to be pure, are used for debugging, > and can be turned off/removed/left as documentation once the proofs > have been checked. (Letting them stay can be a Good Thing if you need > to prepare for the usual uncoordinated multi-player refactorings and > quick fixes.) > > The expressions don't have significant effects as measured by the purpose > of the programs. For example, they may interrupt the normal flow, like > explicit tests, they will send a mail message with some state information > in it and ask for an optional user report. These reports are extremely helpful. > > Checks can be written as if there was monitoring hardware, hence as > if they did not even have a way of toggling any of the program's bits. Actually, in a large project we deploy a similar stuff based GNAT-specific support for tracing exceptions. It is a 50-50 game. In 50% of cases the bug is reported by the monitor. In other 50% it causes a cascade of errors in the monitor itself and around it, makes finding the cause more difficult than without the monitor. I think much, if mot all, boils down to exceptions, because it is practically impossible to ensure safety of controlled objects against unanticipated exceptions. It is non-testable and much too complicated for a programmer to gasp. Contracted exceptions is an urgent need. -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de