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: border1.nntp.dca3.giganews.com!backlog4.nntp.dca3.giganews.com!border4.nntp.dca.giganews.com!border2.nntp.dca.giganews.com!nntp.giganews.com!news.snarked.org!us.feeder.erje.net!feeder.erje.net!eu.feeder.erje.net!news.etla.org!nntp-feed.chiark.greenend.org.uk!ewrotcd!reality.xs3.de!news.jacob-sparre.dk!loke.jacob-sparre.dk!pnx.dk!.POSTED!not-for-mail From: "Randy Brukardt" Newsgroups: comp.lang.ada Subject: Re: Making sense of predicates Date: Wed, 23 Oct 2013 23:03:05 -0500 Organization: Jacob Sparre Andersen Research & Innovation Message-ID: References: <9vlzla1igu9w$.1ifys2xkaugrn$.dlg@40tude.net> NNTP-Posting-Host: static-69-95-181-76.mad.choiceone.net X-Trace: loke.gir.dk 1382587386 9172 69.95.181.76 (24 Oct 2013 04:03:06 GMT) X-Complaints-To: news@jacob-sparre.dk NNTP-Posting-Date: Thu, 24 Oct 2013 04:03:06 +0000 (UTC) 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 V6.00.2900.6157 X-Original-Bytes: 2765 Xref: number.nntp.dca.giganews.com comp.lang.ada:183713 Date: 2013-10-23T23:03:05-05:00 List-Id: "Dmitry A. Kazakov" wrote in message news:9vlzla1igu9w$.1ifys2xkaugrn$.dlg@40tude.net... > On Mon, 21 Oct 2013 23:35:59 -0500, Randy Brukardt wrote: > >> It should be one step (only). We'd need something like co-derivation for >> that, which might make sense to pursue someday (the main reason would be >> to >> get rid of access types altogether, but to do that you need some sort of >> handle, like the container cursor -- and clearly you need to be able to >> derive the container and its handle together). But that would be a big >> job >> to define properly, it would take the existing inheritance rules and make >> them much more complex. (There are already 3 pages of rules associated >> with >> inheritance for derived types.) > > It is not only access types. It is relationships between types: Pointer - > Target, Array - Index - Element, etc. Yes, of course. The idea is that you'd be able to declare any set of types as "co-tagged" or something like that. (I'm thinking on the fly here, so don't read anything much into the names.) Then they'd have to be derived (extended) together as a group. > If you try, as Ada designers keep on doing, to handle that at the language > level for each built-in type individually, you indeed end up with > something > as horrific as accessibility rules are. That does not work. That's doesn't remotely resemble what I was thinking of; I was only thinking about a new kind of derivation and possibly a new kind of tagged type. Basic building blocks, nothing "built-in". Randy.