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: 103376,38730e01f356adfa X-Google-Attributes: gid103376,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news3.google.com!news4.google.com!news.glorb.com!cycny01.gnilink.net!spamkiller2.gnilink.net!gnilink.net!trndny03.POSTED!c2bfcbcf!not-for-mail Subject: Re: types and subtypes Newsgroups: comp.lang.ada References: <1142251677.837212.109000@i39g2000cwa.googlegroups.com> <1142273325.634632.41020@j52g2000cwj.googlegroups.com> From: "Ed Falis" Content-Type: text/plain; format=flowed; delsp=yes; charset=iso-8859-15 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Message-ID: User-Agent: Opera M2/8.52 (Win32, build 7721) Date: Mon, 13 Mar 2006 18:17:21 GMT NNTP-Posting-Host: 70.22.165.82 X-Complaints-To: abuse@verizon.net X-Trace: trndny03 1142273841 70.22.165.82 (Mon, 13 Mar 2006 13:17:21 EST) NNTP-Posting-Date: Mon, 13 Mar 2006 13:17:21 EST Xref: g2news1.google.com comp.lang.ada:3340 Date: 2006-03-13T18:17:21+00:00 List-Id: On Mon, 13 Mar 2006 13:08:45 -0500, wrote: > Why was Ada's subtyping defined to exclude derivation? Derived types in Ada, whether tagged or not, are the same as the conventional usage of the term "subtype" in other OO languages. Subtypes in Ada are about adding constraints on the range of acceptable values, rather than emphasizing type extension and overriding of subprograms, which is the role of a derived type. Ada's use of the term "subtype" preceded the development of most OO languages (Simula 67 being a noteworthy exception, and probably Smalltalk). - Ed