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=0.2 required=5.0 tests=BAYES_00,INVALID_MSGID, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,d1df6bc3799debed X-Google-Attributes: gid103376,public From: "John G. Volan" Subject: Re: Not intended for use in medical, Date: 1997/05/12 Message-ID: <3376CF85.3E15@sprintmail.com>#1/1 X-Deja-AN: 241013931 References: <3.0.32.19970423164855.00746db8@mail.4dcomm.com> <5kl9qc$g4d@bcrkh13.bnr.ca> <5kmek2$9re@bcrkh13.bnr.ca> <33727FA5.5C7A@sprintmail.com> <3374C19F.15FE@sprintmail.com> Organization: Sprint Internet Passport Reply-To: johnvolan@sprintmail.com Newsgroups: comp.lang.ada Date: 1997-05-12T00:00:00+00:00 List-Id: Robert Dewar wrote: > > John said > > < (and most recently in an article in the March/April 1997 Ada Letters) > that tagged type inheritance -- in fact, derived type inheritance in > general -- compromises one of the original design principles of Ada: > locality of declaration.>> > > Yes, of course these arguments are very familiar, they are the arguments > that were used in excluding general inheritance from Ada 83 in the first > place [snip...] > > However, the fact is that the requirements document rejects these > arguments, as did the majority of those involved with the Ada 9X > design. Jean Ichbiah strongly supported the addition of OO facilities > to the language in the context of the redesign of the language for > example. Well that is nice to know! I thought I read somewhere that Jean Ichbiah was resistant to some of those changes. > Your attempt to create the notion that lots of people opposed > these ideas, but they got put in anyway because of political pressure > simply bares no relation to what actually happened! Looks like I read too much into that article in Ada Letters. I got the impression that there is still a significant constituency in the real time industry with serious reservations about OO-style inheritance. Hopefully, it's a dwindling minority. But, to do them justice, we can address their concerns thus: Patient: "Doc, it hurts when I do this." Doctor: "Well, then don't do that!" In other words, tagged types and type derivation are useful tools that have their place, but they are not necessarily the right tool for every problem, and you are not necessarily forced to use them for everything. Make an informed engineering decision, weigh the trade-offs: If the overhead and dynamic dispatching and the indeterminacy of abstract types are unacceptable to a real-time application, just don't use those features. ------------------------------------------------------------------------ Internet.Usenet.Put_Signature (Name => "John G. Volan", Home_Email => "johnvolan@sprintmail.com", Slogan => "Ada95: The World's *FIRST* International-Standard OOPL", Disclaimer => "These opinions were never defined, so using them " & "would be erroneous...or is that just nondeterministic now? :-) "); ------------------------------------------------------------------------