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!news.eternal-september.org!news.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!not-for-mail
From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Getting the index for an element in mutually referencing
 containers
Date: Wed, 15 Mar 2017 15:12:24 -0500
Organization: JSA Research & Innovation
Message-ID: <oac779$ffo$1@franka.jacob-sparre.dk>
References: <86o9xa36oq.fsf@gaheris.avalon.lan> <ly7f3xedp4.fsf@pushface.org>
 <86k27xpikd.fsf@gaheris.avalon.lan> <lywpbxc9my.fsf@pushface.org>
 <86wpbxneuz.fsf@gaheris.avalon.lan> <o9vcbp$t0t$1@franka.jacob-sparre.dk>
 <ly37ekcikw.fsf@pushface.org> <oa0e8f$1g2o$1@gioia.aioe.org>
 <lyy3wcawkj.fsf@pushface.org> <oa10uv$gfl$1@gioia.aioe.org>
 <lytw6zbmve.fsf@pushface.org> <oa1o1j$1tuh$1@gioia.aioe.org>
 <lypohnbi6m.fsf@pushface.org> <oa30d2$1oj3$1@gioia.aioe.org>
 <lya88qbul5.fsf@pushface.org> <oa3cuo$ej0$1@gioia.aioe.org>
 <ly60jebg2v.fsf@pushface.org> <oa41a4$1ko5$1@gioia.aioe.org>
 <oa6teu$r7$1@franka.jacob-sparre.dk> <oa70rj$12td$1@gioia.aioe.org>
 <oa9kgq$3mv$1@franka.jacob-sparre.dk> <oaausp$ddn$1@gioia.aioe.org>
NNTP-Posting-Host: rrsoftware.com
X-Trace: franka.jacob-sparre.dk 1489608745 15864 24.196.82.226 (15 Mar 2017
 20:12:25 GMT)
X-Complaints-To: news@jacob-sparre.dk
NNTP-Posting-Date: Wed, 15 Mar 2017 20:12:25 +0000 (UTC)
X-Priority: 3
X-MSMail-Priority: Normal
X-Newsreader: Microsoft Outlook Express 6.00.2900.5931
X-RFC2646: Format=Flowed; Response
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157
Xref: news.eternal-september.org comp.lang.ada:33515
Date: 2017-03-15T15:12:24-05:00
List-Id: <comp.lang.ada>

"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message 
news:oaausp$ddn$1@gioia.aioe.org...
> On 2017-03-14 21:40, Randy Brukardt wrote:
...
> The problem is that the smart pointer type must be anonymous (ad-hoc) like 
> access T is. Otherwise, you get the problem of parallel type hierarchies 
> of the targets and the pointers. And the pointer type must have the 
> interface of the target AKA implicit dereference.

The problem of parallel type hierarchies is one that MUST be solved if one 
is going to program with hierarchies. It IS fundamental to strong typing, 
unlike most of these other issues. We really need a solution to it (I've 
tried some and intend to try more).

I don't recall ever needing both "strong" or "weak" references to any data 
structure. Most structures only need short-lived references, and the ones 
that need long-lived ones are almost always permanent (only changed between 
runs). Maybe that's because when the only tool you have is an access type, 
every reference looks unchecked and dangerous. :-) But I doubt that many 
problems need or care about the both possibilities.

                          Randy.