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!nntp-feed.chiark.greenend.org.uk!ewrotcd!newsfeed.xs3.de!io.xs3.de!news.jacob-sparre.dk!franka.jacob-sparre.dk!pnx.dk!.POSTED.rrsoftware.com!not-for-mail From: "Randy Brukardt" Newsgroups: comp.lang.ada Subject: Re: interfaces and limited/controlled/limited-controlled types Date: Thu, 25 Jan 2018 22:58:49 -0600 Organization: JSA Research & Innovation Message-ID: References: Injection-Date: Fri, 26 Jan 2018 04:58:50 -0000 (UTC) Injection-Info: franka.jacob-sparre.dk; posting-host="rrsoftware.com:24.196.82.226"; logging-data="11015"; mail-complaints-to="news@jacob-sparre.dk" X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2900.5931 X-RFC2646: Format=Flowed; Original X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.7246 Xref: reader02.eternal-september.org comp.lang.ada:50159 Date: 2018-01-25T22:58:49-06:00 List-Id: "Mehdi Saada" <00120260a@gmail.com> wrote in message news:ea190839-2f83-4dbb-9064-8d6f535cc1d0@googlegroups.com... > Is it only because of history and compatibility issues, that > Limited_Controlled and Controlled aren't rewrote as interfaces ? > Like: T_type is limited new Ancestor_type with Controlled > or T_type is new Ancestor_type with Limited_Controlled > > Or is there a semantic issue too ? A compatibility issue IS a semantic issue! Yes, the main reason is compatibilty. We've looked at ways to allow Root_Streams_Type to be an interface (same problem), and the levels of semantic trouble that occurs makes it a dubious proposition (at least so far). The issue is still open: AI12-0023-1, but it hasn't been worked on since 2012, so I wouldn't hold out much hope that anything will happen here. The last meeting notes discuss some of the problems involved (http://www.ada-auth.org/ai-files/minutes/min-1206.html#AI023). Randy.