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,c5e219ab41be8c00 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2000-12-25 23:31:04 PST Path: supernews.google.com!sn-xit-02!sn-xit-03!supernews.com!newsfeed.direct.ca!look.ca!paloalto-snh1.gtei.net!chicago-news-feed1.bbnplanet.com!news.gtei.net!news.huji.ac.il!not-for-mail From: "Ehud Lamm" Newsgroups: comp.lang.ada Subject: Re: Multiple Interface Inheritance (was Re: JGNAT and ObjectAdaand...) Date: Tue, 26 Dec 2000 09:18:51 +0200 Organization: The Hebrew University of Jerusalem Message-ID: <929gta$q4$1@news.huji.ac.il> References: <3A3E8A9E.D12673A7@libertysurf.fr> <91nur2$ulk$1@nnrp1.deja.com> <3A3F8651.7CDB13B6@averstar.com> <3A410EC1.106C74CC@averstar.com> <3A413FBB.3E852649@averstar.com> <926vah$iu4$1@news.huji.ac.il> NNTP-Posting-Host: di2-11.dialin.huji.ac.il X-Trace: news.huji.ac.il 977815275 836 132.64.12.11 (26 Dec 2000 07:21:15 GMT) X-Complaints-To: abuse@news.huji.ac.il NNTP-Posting-Date: Tue, 26 Dec 2000 07:21:15 +0000 (UTC) X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.00.2014.211 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2014.211 Xref: supernews.google.com comp.lang.ada:3395 Date: 2000-12-26T09:18:51+02:00 List-Id: Brian Rogoff wrote in message news:Pine.BSF.4.21.0012251022110.1095-100000@shell5.ba.best.com... > On Mon, 25 Dec 2000, Ehud Lamm wrote: > > Brian Rogoff wrote in message > > My feeling is that as a porposal for an extension to the existing language, > > this seems quite nice (I didn't consider all the details yet, so I don't > > want to say anything more definite/interesting). > > I'm still constructing little examples, by translating simple things from > Java. I expect that Tucker and others are much better equipped than I to > decide what may be feasible (or possible!) to implement in an Ada > extension, however, as long as we're considering such a feature I think it > would be reasonable to look beyond what Java has. Quite so! > > > To really achive the state-of-the-art interface support, I think many many > > features in the language should be redesigned, and I think doing this is > > unreasonable. > > I agree completely, but the signature extension of C++ is by no means the > final word on subtype polymorphism. Remember, it was a restricted > extension to an existing language (C++) and it was limited compared to > other languages at the time (Axioms' internal language, called A# I think) > so it would hardly be "state-of-the-art". It may still not mesh well with > Ada, and that is what I am curious about. What made you think I think this is the final word? I was speaking about designing/inventing a new approach, not about simply taking ideas from Java, g++ or even Ocaml... > > > These ideas are best left for a new language to implement. > > If I'm really desparate for this capability I can use Ocaml ;-). But I > think there are still good reasons for Ada, and I'm a bit peeved when I > read that some European Space Agency projects switch to C++ because of > Ada's (admittedly clunky) support for MI of interface. It will only get > worse as Java gets more popular IMO, since interfaces really do show off > the most important aspect of OO, namely (run time) polymorphism. > > So, while I agree that a new (Ada inspired) language might be a good thing > I really think improving what we have now is more important. And this is > an area where there is an undisputed "customer demand". I agree 100%. That's why I wrote that what I am thinking about is "not in the cards." I meant to say (and perhaps did'nt make myself clear) that it is important to extend the language to allow things like ESA wants, and that the AI proposal seemed to be in the right direction. > > [...snip...] > > I'd prefer a lanuage more refined in its OVERALL apporahc to interfaces. > > (e.g, supose we have 'Interface. What operations are allowed on this? Are > > interface first class? I guess not) > > Not sure I follow you here. Interfaces aren't first class in Java, and > packages aren't first class in Ada. As I said, I am thinking beyond what these offer. (+ even if interfaces aren't first class, you should still decide what operations are applicabe to the imagend 'Interface) > > > All these fascinating topics, IMO, but I think for Ada0X we must be modest. > > Ada9X did a wonderful job incorporating inheritance into Ada, and I'd love > > to see a solution of this quality to these issues. But even the best > > solutions (and the AI does indeed look convincing) still seem to me to be > > limited in scope. I am afraid I can't offer something better (or even > > somethng that SEEMS better), without proposing a major change in the > > language, and this is simply not in the cards... > > This all seems vague to me. "Something better/more powerful" may still be > limited in scope. I still suggested an explict 'Interface or sigof rather > than suggesting inference, which is more powerful yet. All I want to know > is whether the ability to an extract an (anonymous?) interface from an > existing tagged type might reasonably be added to the proposal. > > -- Brian > And I wasn't suggesting/asking for anything, just giving another (perhaps vague) perspective. -- Ehud Lamm mslamm@mscc.huji.ac.il