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=-0.3 required=5.0 tests=BAYES_00,
	REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4
X-Google-Thread: 103376,a575249b5f286bfe
X-Google-NewGroupId: yes
X-Google-Attributes: gida07f3367d7,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Received: by 10.68.233.170 with SMTP id tx10mr2409269pbc.0.1334905908421;
        Fri, 20 Apr 2012 00:11:48 -0700 (PDT)
Path: 
 r9ni77161pbh.0!nntp.google.com!news2.google.com!goblin1!goblin2!goblin.stu.neva.ru!aioe.org!.POSTED!not-for-mail
From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Garbage Collection ???
Date: Fri, 20 Apr 2012 09:11:18 +0200
Organization: cbb software GmbH
Message-ID: <itjg3eh0o4s8.rm273bcoi1tb$.dlg@40tude.net>
References: <4f881910$0$2652$703f8584@news.kpn.nl>
 <5o86o2smbjpz.17l849bmku28v$.dlg@40tude.net>
 <4f888010$0$2641$703f8584@news.kpn.nl> <jmaai4$aga$1@dont-email.me>
 <4f88ed79$0$2660$703f8584@news.kpn.nl> <wccy5pymaxu.fsf@shell01.TheWorld.com>
 <6997433.1158.1334740025722.JavaMail.geo-discussion-forums@ynmm10>
 <wcc4nsf4wm4.fsf@shell01.TheWorld.com> <jmpscu$ui7$1@munin.nbi.dk>
Reply-To: mailbox@dmitry-kazakov.de
NNTP-Posting-Host: FbOMkhMtVLVmu7IwBnt1tw.user.speranza.aioe.org
Mime-Version: 1.0
X-Complaints-To: abuse@aioe.org
User-Agent: 40tude_Dialog/2.0.15.1
X-Notice: Filtered by postfilter v. 0.8.2
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Date: 2012-04-20T09:11:18+02:00
List-Id: <comp.lang.ada>

On Thu, 19 Apr 2012 15:26:03 -0500, Randy Brukardt wrote:

> (And a null-excluding component - by any means - is almost never a good 
> idea.

The idea is good, bad is lthe ack of means to initialize such components
properly. You know what I mean. (:-))

> You always need a "nothing/unknown" indicator.

I am using a scheme when non-null pointer components are initialized to a
stock object. It works, but becomes very uncomfortable when the record
itself is in a generic and the target type is tagged. I need to derive not
only the type itself, but also the stock object type, override its
operations to null/alarm, create the stock singleton etc.

> Null-exclusions are 
> almost exclusively useful for parameters, where you don't need "nothing" 
> simply because you don't make the call in that case.)

and access discriminants, certainly.

However both cases do not feel good. I mean why there should be a pointer?
Is it always a reference semantics? Frequently it is not. But even if the
semantics is indeed referential, why explicit pointer?

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de