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: 103376,8591be732d0fce98 X-Google-Attributes: gid103376,domainid0,public,usenet X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news1.google.com!border1.nntp.dca.giganews.com!border2.nntp.dca.giganews.com!nntp.giganews.com!newspeer1.nac.net!newspeer.monmouth.com!newsswitch.lcs.mit.edu!nntp.TheWorld.com!not-for-mail From: Robert A Duff Newsgroups: comp.lang.ada Subject: Re: Ada OOP alternatives? Date: Tue, 15 Jul 2008 20:15:05 -0400 Organization: The World Public Access UNIX, Brookline, MA Message-ID: References: <462e0cf4-1d53-4918-b30b-dd3d8df90f1b@p25g2000hsf.googlegroups.com> NNTP-Posting-Host: shell01.theworld.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: pcls4.std.com 1216167306 15353 192.74.137.71 (16 Jul 2008 00:15:06 GMT) X-Complaints-To: abuse@TheWorld.com NNTP-Posting-Date: Wed, 16 Jul 2008 00:15:06 +0000 (UTC) User-Agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/21.3 (irix) Cancel-Lock: sha1:fYuoe3+RbwchOC86PJjq4brisBA= Xref: g2news1.google.com comp.lang.ada:1164 X-Original-Bytes: 2617 Date: 2008-07-15T20:15:05-04:00 List-Id: raould writes: > might anybody know what the different designs were for OO in Ada? what > was Ichbiah's design, vs. the one that went through? thanks. Interesting question. As far as I know, Ichbiah didn't have a design for OO in Ada 95. He wanted the syntax to be something like "class type T is...", as opposed to "type T is tagged...", and he _very_ much wanted "class" to be a reserved word, rather than a mere attribute. I don't remember Ichbiah proposing any detailed semantics for "class type T is...". His concern, as far as I know, was syntax-oriented. Of course Ichbiah knew all about OO when he designed Ada 83 -- I'm told he was familiar with Simula 67, for ex., which is the Mother of all OOP languages. He left OO out of Ada 83 deliberately. I've no idea whether that was his own choice, or forced by some requirements document like Steelman. And Ichbiah invented Ada's derived types, upon which Tucker Taft based OO in Ada 95. I've no idea whether Ichbiah had that sort of thing in mind when he invented derived types. But I've been told that derived types were controversial for Ada 83 -- the reviewers thought they were useless nonsense, but Ichbiah insisted on keeping them in the language design. As for other (non-Ichbiah) designs, well I've seen various proposals for "package types", treating Ada packages like "classes" in languages like Simula-67, Java, C++, etc. I'm not sure that works. E.g. the question arises whether types declared in two different "package objects" of the same "package type" should be the same type. I'm not sure it does _not_ work, either. ;-) - Bob