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: 103376,7d83a6223f4f2443
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!nntp.giganews.com!newsfeed00.sul.t-online.de!newsfeed01.sul.t-online.de!t-online.de!newsfeed.arcor.de!newsspool4.arcor-online.net!news.arcor.de.POSTED!not-for-mail
From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Run-time accessibility checks
Newsgroups: comp.lang.ada
User-Agent: 40tude_Dialog/2.0.15.1
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Reply-To: mailbox@dmitry-kazakov.de
Organization: cbb software GmbH
References: <txbc0ucekvix.ntpy85qsan7h$.dlg@40tude.net>
 <ghpoep$i61$1@munin.nbi.dk> <u7htidgqfmwu$.i9oewoweyrhe$.dlg@40tude.net>
 <4940f7be$0$30232$9b4e6d93@newsspool1.arcor-online.net>
Date: Thu, 11 Dec 2008 12:40:32 +0100
Message-ID: <1abvztyo27831.169xig7skkqig$.dlg@40tude.net>
NNTP-Posting-Date: 11 Dec 2008 12:40:32 CET
NNTP-Posting-Host: 38e36e52.newsspool3.arcor-online.net
X-Trace: 
 DXC=D7Wk;4iO]37L2C_`koXfC5McF=Q^Z^V384Fo<]lROoR1^YC2XCjHcb99W17=RC[jS1DNcfSJ;bb[5FCTGGVUmh?4LK[5LiR>kg2IHf\C^^Z_=:
X-Complaints-To: usenet-abuse@arcor.de
Xref: g2news1.google.com comp.lang.ada:2960
Date: 2008-12-11T12:40:32+01:00
List-Id: <comp.lang.ada>

On Thu, 11 Dec 2008 12:21:34 +0100, Georg Bauhaus wrote:

> Dmitry A. Kazakov schrieb:
> 
>> This is what I call abstract record interface. For each component it will
>> have two operations:
>> 
>>    function ".<component>" (R : Abstract_Record_Type)
>>       return Component_Type is abstract;
>>    procedure ".<component>"
>>       (R : in out Abstract_Record_Type; C : Component_Type) is abstract;
>> 
>> The compiler uses the second (setter) for all LHS X.Component.
> 
> That with pre/post/invariant constraints, in case the
> component setting procedure has access to the object
> containing the component.

It is a primitive operation of the abstract record type, but not of the
component. If you wanted to have it a primitive operation of both, you
would have to support MD, which is I don't know how to do (properly).

> Could pre/post/invariant also help when checking order of
> component assignments?

Which order? A record type does not declare any specific access order for
its components. If you have record aggregates in mind that is another
interface and another issue. Aggregate is a form of a constructor with some
special syntax.

> (These are called "assigner commands" in Eiffel.)

There are pretty clear rules about what happens with pre/post/invariant
upon inheritance (Liskov). The only problem is that many people (like Meyer
and possibly you) honestly believe they could make pre/post/invariant
dynamic. Count me out.

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