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=-1.3 required=5.0 tests=BAYES_00,MAILING_LIST_MULTI, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,f5de0f20558e30f2,start X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2003-01-12 22:13:03 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!canoe.uoregon.edu!logbridge.uoregon.edu!fr.usenet-edu.net!usenet-edu.net!enst.fr!not-for-mail From: "Grein, Christoph" Newsgroups: comp.lang.ada Subject: Implicit Instantiations - was: Re: Why is Ada NOT a good choice for a beginner to programming? Date: Mon, 13 Jan 2003 07:05:29 +0100 (MET) Organization: ENST, France Sender: comp.lang.ada-admin@ada.eu.org Message-ID: Reply-To: comp.lang.ada@ada.eu.org NNTP-Posting-Host: marvin.enst.fr Mime-Version: 1.0 Content-Type: TEXT/plain; charset=us-ascii X-Trace: avanie.enst.fr 1042438383 37983 137.194.161.2 (13 Jan 2003 06:13:03 GMT) X-Complaints-To: usenet@enst.fr NNTP-Posting-Date: Mon, 13 Jan 2003 06:13:03 +0000 (UTC) Return-Path: X-Authentication-Warning: mail.eurocopter.com: uucp set sender to using -f Content-MD5: 5umNNTW04Fp259Edl5ZMyQ== X-Mailer: dtmail 1.2.1 CDE Version 1.2.1 SunOS 5.6 sun4u sparc Errors-To: comp.lang.ada-admin@ada.eu.org X-BeenThere: comp.lang.ada@ada.eu.org X-Mailman-Version: 2.0.13 Precedence: bulk X-Reply-To: "Grein, Christoph" List-Unsubscribe: , List-Id: comp.lang.ada mail<->news gateway List-Post: List-Help: List-Subscribe: , Errors-To: comp.lang.ada-admin@ada.eu.org X-BeenThere: comp.lang.ada@ada.eu.org Xref: archiver1.google.com comp.lang.ada:32951 Date: 2003-01-13T07:05:29+01:00 From: kcline17@hotmail.com (Kevin Cline) > Grein writes: > > But the request to have full dimensional checking persists as can be seen > from the pertinent discussions in newsgroup Comp.Lang.Ada. There are two > basic ways one can try to solve the problem, either by adding to the > numeric value its dimension as attribute, or by using different types for > different dimensions. Since the first method is runtime-consuming, > whereas the second one is only compiletime-consuming, all effort naturally > concentrates on the second method. This is doomed to fail > as is shown in the paper cited above - although a plethora of overloaded > operations is used, the result is not really satisfactory. > Physical equations with all their powers and roots evade these attempts. > > In short, Ada's requirement for explicit generic instantiation repels > attempts to create a compile-time verified system of dimensional types, > and Grein gave up on attempts to achieve compile-time type safety. > > C++ does not have this problem, and compile-time type safety is > achieved in a fairly obvious way. This C++ feature pleases me so that I'm apt to wish something like it were available in Ada. However I have not thought about all implications this would induce in connection with all other features in Ada, so this might turn out to be a kind of Pandora's box. It is true, there are some places in Ada where implicit declarations or type conversions are done, but implicit instantiations are as yet nowhere.