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=unavailable autolearn_force=no version=3.4.4 Path: eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!feeder.eternal-september.org!aioe.org!.POSTED!not-for-mail From: "J-P. Rosen" Newsgroups: comp.lang.ada Subject: Re: Ada Successor Language Date: Tue, 26 Jun 2018 22:16:23 +0200 Organization: Adalog Message-ID: References: <5e86db65-84b9-4b5b-9aea-427a658b5ae7@googlegroups.com> <878t7u1cfm.fsf@nightsong.com> <776f3645-ed0c-4118-9b4d-21660e3bba4b@googlegroups.com> <87602fbu2g.fsf@nightsong.com> <87po0mziqt.fsf@nightsong.com> <87fu1izfgs.fsf@nightsong.com> <878t75nwad.fsf@adaheads.home> NNTP-Posting-Host: XdjV4tYMtFfMKGpv0MuDzQ.user.gioia.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Complaints-To: abuse@aioe.org User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 Content-Language: fr X-Notice: Filtered by postfilter v. 0.8.3 Openpgp: preference=signencrypt Xref: reader02.eternal-september.org comp.lang.ada:53346 Date: 2018-06-26T22:16:23+02:00 List-Id: Le 25/06/2018 à 16:03, Niklas Holsti a écrit : > So it says in RM 3.4(5/2), but even the Annotated RM has no motivation > for it, and I don't see why Ada could not assume a null extension when > the type is tagged. Can someone explain why the RM is so strict on this? > > (In fact, it seems to me that Ada could allow untagged record extensions > as well; the effect would be the same as for tagged ones, but no 'Class > would be formed, and no class-wide programming or dynamic dispatch could > be used, so all such types would be static. It would be semantically > equivalent to aggregation of a component of the parent type with the > extension components, but would allow direct access to the inherited > components from the parent type. This could be a useful separation of > extensions from tags.) You can achieve exactly this with a tagged type and Restriction (No_Dispatch) -- J-P. Rosen Adalog 2 rue du Docteur Lombard, 92441 Issy-les-Moulineaux CEDEX Tel: +33 1 45 29 21 52, Fax: +33 1 45 29 25 00 http://www.adalog.fr