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-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,1dd28d5040ded1f8 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2002-05-22 00:45:56 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!fu-berlin.de!uni-berlin.de!pec-71-188.tnt4.hh2.uunet.DE!not-for-mail From: Dmitry A. Kazakov Newsgroups: comp.lang.ada Subject: Re: Announce: Grace project site operational Date: Wed, 22 May 2002 09:48:08 +0200 Message-ID: <13imeusdlk5hdvdcr2uf2fn1amcpd6jb16@4ax.com> References: <3CE15D0A.3050100@mail.com> <2s44eu0fm4g6606h9p4stb1b5oc0nmg5u8@4ax.com> <3CE2A946.5030808@mail.com> <3CE40B8E.70102@mail.com> <3CE92D80.7040904@mail.com> <3CEA6E68.6040102@mail.com> NNTP-Posting-Host: pec-71-188.tnt4.hh2.uunet.de (149.225.71.188) Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Trace: fu-berlin.de 1022053554 26828720 149.225.71.188 (16 [77047]) X-Newsreader: Forte Agent 1.8/32.548 Xref: archiver1.google.com comp.lang.ada:24505 Date: 2002-05-22T09:48:08+02:00 List-Id: On Tue, 21 May 2002 11:57:28 -0400, Hyman Rosen wrote: >Dmitry A. Kazakov wrote: >> On Mon, 20 May 2002 13:08:16 -0400, Hyman Rosen >> wrote: >>>Why is a kilometer at all related to an hour? >>>Why do they need a common supertype? >> >> Because, there is a gauge that can show both. Because there is a data >> base which is able to store measures with their dimensions, etc. > >I am sitting in front of a monitor that can display anything. Compare dimensioned values and strings. The string length is not a part of the type it is a constraint. Same is valid for dimension. Then your logic is wrong. Your monitor CAN display anything, but it DOES NOT. How "anything" looks like? (:-)) >By your logic, all data types should therefore have a common >supertype. Shrug. This is another question. The answer is yes and no. No because only related types should have a common ancestor. Yes because in some sense (defined by the application) all types CAN be related. Consider 'Size attribute. It is an operation applied to any type, so there is a common ancestor type from which they inherit it. A good language should allow to create supertypes (common ancestors) as necessary, because types related for one application might be unrelated for another. If you get tired to write To_String each time you have to convert an unbounded string to a string, define a common ancestor for both and here you are. >You program in your way, and I'll program >in mine. Absolutely no objection here. --- Regards, Dmitry Kazakov www.dmitry-kazakov.de