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: 103376,2ff5c149712ec0eb X-Google-Attributes: gid103376,public,usenet X-Google-Language: ENGLISH,ASCII-7-bit Newsgroups: comp.lang.ada Subject: Re: Ada Interfaces and the Liskov Substitution Principle References: <1179953657.839272.160320@a26g2000pre.googlegroups.com> <1179991769.376381.252010@m36g2000hse.googlegroups.com> <12h6mi42jcha0.7f9vfsnihjwr$.dlg@40tude.net> <1180003336.1163.29.camel@kartoffel> <83abvs7sa9.fsf@hod.lan.m-e-leypold.de> <465aa5ba$0$23147$9b4e6d93@newsspool1.arcor-online.net> From: Markus E Leypold Organization: N/A Date: Mon, 28 May 2007 15:56:36 +0200 Message-ID: <12abvpqcff.fsf@hod.lan.m-e-leypold.de> User-Agent: Some cool user agent (SCUG) Cancel-Lock: sha1:ClM8P9qsG/is6qrQVn1z01a2XUM= MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii NNTP-Posting-Host: 88.74.52.169 X-Trace: news.arcor-ip.de 1180360049 88.74.52.169 (28 May 2007 15:47:29 +0200) X-Complaints-To: abuse@arcor-ip.de Path: g2news1.google.com!news2.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!newsfeed00.sul.t-online.de!t-online.de!storethat.news.telefonica.de!telefonica.de!news-fra1.dfn.de!newsfeed.arcor-ip.de!news.arcor-ip.de!not-for-mail Xref: g2news1.google.com comp.lang.ada:15954 Date: 2007-05-28T15:56:36+02:00 List-Id: > I bet that as soon as someone popularizes a mathematical model > that does away with variance issues for example, then people will > stop fighting over contravariance versus covariance. > Until then, only this or that kind of variance is allowed to exist, > for either mathematical or problem domain reasons, because the > other solution cannot but create an unmaintainable mess... > > If I had the money, I'd put up a challange that triggers some > programming oriented model research (as opposed to research that > will move the focus of modelling to formal properties of models > only.) Somehow you seem to think, we can just do away with the models, if we just approach it right. That ignores (a) historical experience -- see structured programming which has become so commonplace that we don't percieve it as exceptional any more, and (b) that there is no alternative[tm]: As you can't do quantum mechnics without a certain amount of a certain sort of mathematics you cannot state a contract or specify a design without some sort of logical and basically mathematical model behind. Without you don't even have a language to complain to your compiler writer about bugs. Progress, well, progresses. We get used to it, but it usually doesn't go away. The hope to get rid of "the variance issue" (which actually is just a point in how contracts can be stated precisely) after we discovered it, is just misguided. Regards -- Markus