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=-0.3 required=5.0 tests=BAYES_00, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 Path: eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!mx02.eternal-september.org!feeder.eternal-september.org!aioe.org!.POSTED!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: Why does `Unchecked_Deallocation` need the access type? Date: Wed, 29 Jul 2015 08:28:54 +0200 Organization: cbb software GmbH Message-ID: References: <5d6faxxdsssv.15g7kj5hv86mk$.dlg@40tude.net> <170ajsv4tazu3.mgrs0or8en9w$.dlg@40tude.net> Reply-To: mailbox@dmitry-kazakov.de NNTP-Posting-Host: 5CNUwuQ0q1vZOSDFkeKrYQ.user.speranza.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Complaints-To: abuse@aioe.org User-Agent: 40tude_Dialog/2.0.15.1 X-Notice: Filtered by postfilter v. 0.8.2 Xref: news.eternal-september.org comp.lang.ada:27108 Date: 2015-07-29T08:28:54+02:00 List-Id: On Tue, 28 Jul 2015 16:25:19 -0500, Randy Brukardt wrote: > "Dmitry A. Kazakov" wrote in message > news:170ajsv4tazu3.mgrs0or8en9w$.dlg@40tude.net... >> 3. Tagged hierarchies >> >> type S is new T with private; >> >> S'Parent (T'Class) = T (in a public context) >> >> The argument indicates the hierarchy where to search for the ancestor (due >> to MI). > > We tried such an attribute sometime during the Ada 2005 work and eventually > gave up. The problem being that the parent (in a language sense - it's the > subtype after "new") depends on the visibility on the type, and that is very > unconfortable (besides causing problems): > > package P is > type S is new T with private; > procedure Bar (Obj : in out S'Parent); -- S'Parent is T here. > private > type S in new U with private; -- U is descended from T, of course. > end P; > > package body P is > procedure Bar (Obj : in out S'Parent) is -- !! - S'Parent is U here. I see. Perhaps: procedure Bar (Obj : in out S'Public_Parent) is -- S'Parent is U here -- S'Public_Parent is still T ------------------------ Of course nobody should ever declare non-primitive operations defined on the parent type. And doing that in the public scope is almost a criminal offense. If we designed Ada from a fresh start I would try to eliminate all non-primitive operations. Any operations would be either primitive or class-wide. And a class-wide operation would be still primitive of T'Class and thus dispatch on T'Class'Class etc. -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de