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 Path: border2.nntp.dca1.giganews.com!nntp.giganews.com!usenet.blueworldhosting.com!feeder01.blueworldhosting.com!feeder.erje.net!eu.feeder.erje.net!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: How to get nice with GNAT? Date: Thu, 27 Nov 2014 10:01:16 +0100 Organization: cbb software GmbH Message-ID: <1ukyfvaqgkwo1.6ngfx1v21twz$.dlg@40tude.net> References: <969708583438656051.436159nonlegitur-futureapps.invalid@reader80.eternal-september.org> <0d085a5a-d4ac-4506-ae5f-8da685f39004@googlegroups.com> Reply-To: mailbox@dmitry-kazakov.de NNTP-Posting-Host: laNruIVATSkD3QNnxceKvQ.user.speranza.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Complaints-To: abuse@aioe.org User-Agent: 40tude_Dialog/2.0.15.1 X-Notice: Filtered by postfilter v. 0.8.2 Xref: number.nntp.giganews.com comp.lang.ada:191065 Date: 2014-11-27T10:01:16+01:00 List-Id: On Wed, 26 Nov 2014 14:38:29 -0800 (PST), brbarkstrom@gmail.com wrote: > I think it may be sensible to think of exceptions as contingent events > that we couldn't include in the original design because > a) we aren't omniscient > [as a subset of that] a1) we're building complex mechanisms that have > unexpected interactions between the parts ? > b) the environment in which the program operates changes in unpredictable > ways > As a result, we are nearly certain to discover unexpected events only after > we put the system into operation. No. Exceptions are *expected* events (system states), always. An unexpected event is when a nuke falls down on the system box. Bugs are unexpected events. Exception propagation is not a bug. It is a valid and anticipated system state. Compare it with 2x3 computed as 5 because addition was used instead of multiplication. This is also a bug, but there is nothing vicious in addition per se. -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de