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=ham
	autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,6009c73a58f787a0
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 2002-01-17 02:56:08 PST
Path: 
 archiver1.google.com!news1.google.com!newsfeed.stanford.edu!canoe.uoregon.edu!logbridge.uoregon.edu!news-FFM2.ecrc.net!news.iks-jena.de!lutz
From: lutz@iks-jena.de (Lutz Donnerhacke)
Newsgroups: comp.lang.ada
Subject: Re: How to avoid unreferenced objects (mutexes etc)
Date: Thu, 17 Jan 2002 10:55:57 +0000 (UTC)
Organization: IKS GmbH Jena
Message-ID: <slrna4dbdr.kn.lutz@taranis.iks-jena.de>
References: <3c3ee8c8.105408250@News.CIS.DFN.DE>
 <a1o2h1$sfe3f$5@ID-25716.news.dfncis.de> <3c429d1c.2624281@News.CIS.DFN.DE>
 <a21u43$u3f33$2@ID-25716.news.dfncis.de> <3c45865f.2709203@News.CIS.DFN.DE>
 <u4bhe4qre43f89@corp.supernews.com> <3c468b1a.69461281@News.CIS.DFN.DE>
 <slrna4d5pt.kn.lutz@taranis.iks-jena.de> <3c46a853.76943187@News.CIS.DFN.DE>
NNTP-Posting-Host: taranis.iks-jena.de
X-Trace: branwen.iks-jena.de 1011264957 4055 217.17.192.37 (17 Jan 2002
 10:55:57 GMT)
X-Complaints-To: usenet@iks-jena.de
NNTP-Posting-Date: Thu, 17 Jan 2002 10:55:57 +0000 (UTC)
User-Agent: slrn/0.9.6.3 (Linux)
Xref: archiver1.google.com comp.lang.ada:19007
Date: 2002-01-17T10:55:57+00:00
List-Id: <comp.lang.ada>

* Dmitry A. Kazakov wrote:
>* lutz@iks-jena.de (Lutz Donnerhacke) wrote:
>>* Dmitry A. Kazakov wrote:
>>>I believe it is worth to allow that for all types, i.e. to allow
>>>overriding a non-abstract subroutine with an abstract one. A
>>>dispatching call to a disallowed subprogram will then raise an
>>>exception [like when tags of arguments are different].
>>
>>I strongly discourage from such a change. Class wide programming using
>>abstract tagged types are used for the guarantee of a working interface.
>
>There is no way to enforce LSP, if you aim at that. Just consider an
>overriding like:
>
>procedure Do_Something (...) is
>begin
>   raise Program_Error;
>end Do_Something;

Then the reason is on client site. Which is easy to detect.

>And who said that derived types shall be LSP subtypes?

The generic preamble requiring the correct instantiation.