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,FREEMAIL_FROM autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,103b407e8b68350b X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2003-01-31 09:25:18 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!logbridge.uoregon.edu!arclight.uoregon.edu!news.tufts.edu!uunet!dca.uu.net!ash.uu.net!spool0900.news.uu.net!reader0900.news.uu.net!not-for-mail Date: Fri, 31 Jan 2003 12:25:16 -0500 From: Hyman Rosen User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.3b) Gecko/20030130 X-Accept-Language: en-us, en MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: Anybody in US using ADA ? One silly idea.. References: <1043680098.61106@master.nyc.kbcfp.com> <3afc3v4uur2kvd53v4ul18b5npjfm188o3@4ax.com> <1043773909.385612@master.nyc.kbcfp.com> <1043855067.848326@master.nyc.kbcfp.com> <1043938878.313737@master.nyc.kbcfp.com> <1043949677.919365@master.nyc.kbcfp.com> <1044025904.464559@master.nyc.kbcfp.com> In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Organization: KBC Financial Products Message-ID: <1044033916.943076@master.nyc.kbcfp.com> Cache-Post-Path: master.nyc.kbcfp.com!unknown@nightcrawler.nyc.kbcfp.com X-Cache: nntpcache 3.0.1 (see http://www.nntpcache.org/) NNTP-Posting-Host: 204.253.250.10 X-Trace: 1044033918 reader0.ash.ops.us.uu.net 28774 204.253.250.10 Xref: archiver1.google.com comp.lang.ada:33652 Date: 2003-01-31T12:25:16-05:00 List-Id: Dmitry A. Kazakov wrote: > Do you know, an integer is definitely a real number. So you should > clarify whether you are talking about mathematical objects or their > computer models. Computer models. As I said, the main mistake of OO is confusing the computer objects with the things they are partially modelling. > This why the representation of a particular type should be no issue, > when subtyping is considered. Perhaps for your concept of subtyping, but not for mine. If you want Ada-style view conversions, that does not have anything to do with subtyping, just interconvertability. To quote the Ada RM: "In a view conversion for an untagged type, the target type shall be convertible (back) to the operand type." > However I see no sense in appealing to authority. If in your view to > say that an object has a type is not feasible, then please, show why. I should apologize for my unfamiliarity with Ada. An Ada subtype is a restricted subset of its parent type. But the conventional OO term subtype used for derived types is not such a restriction, and indeed Ada calls that a derived type, not a subtype. Anyway, I don't say that an object doesn't have a type, but that it can simultaneously have many types. Applying the Ada definition works perfectly well in this context. If my object is simultaneously an A and a B and a C, then it is a run-time entity which contains a value of the set of values of A, and a value of the set of values of B, and a value of the set of values of C.