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
Path: 
 eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: "G.B." <bauhaus@notmyhomepage.invalid>
Newsgroups: comp.lang.ada
Subject: Re: Ada 2012 Constraints (WRT an Ada IR)
Date: Wed, 14 Dec 2016 17:31:34 +0100
Organization: A noiseless patient Spider
Message-ID: <o2rs2j$e8d$1@dont-email.me>
References: <c06ee4e6-d616-4e01-ba2e-cb111a81f6f6@googlegroups.com>
 <o28non$1fn8$1@gioia.aioe.org> <o2a2ad$vnp$1@franka.jacob-sparre.dk>
 <o2b79r$1dit$1@gioia.aioe.org> <o2b9rg$ejl$1@dont-email.me>
 <o2bb4o$1jpb$1@gioia.aioe.org> <o2c93i$rpp$2@dont-email.me>
 <o2du2t$1ghu$1@gioia.aioe.org> <o2jcpd$75p$1@dont-email.me>
 <o2jgom$18jg$1@gioia.aioe.org> <o2jkdm$bt$1@dont-email.me>
 <o2js2d$1qh4$1@gioia.aioe.org> <o2ke6d$gcs$1@dont-email.me>
 <o2ln13$et0$1@gioia.aioe.org> <o2mfpc$ttp$1@dont-email.me>
 <o2mncc$gjn$1@gioia.aioe.org> <o2mroh$dsk$1@dont-email.me>
 <o2n2o1$1515$1@gioia.aioe.org> <o2o73n$ci1$1@dont-email.me>
 <o2obed$qkk$1@gioia.aioe.org> <o2oj2u$i8h$1@dont-email.me>
 <o2olfi$1ca9$1@gioia.aioe.org> <o2p9bb$bcf$1@dont-email.me>
 <o2po6a$1hnq$1@gioia.aioe.org>
 <999c67b0-4478-4d2b-8108-32ac48fe6316@googlegroups.com>
 <o2r0lo$175u$1@gioia.aioe.org> <o2r8tr$bc9$1@dont-email.me>
 <o2ra79$1ns2$1@gioia.aioe.org> <o2reo1$ugh$1@dont-email.me>
 <o2rfan$f4$1@gioia.aioe.org>
Reply-To: nonlegitur@notmyhomepage.de
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 8bit
Injection-Date: Wed, 14 Dec 2016 16:30:11 -0000 (UTC)
Injection-Info: mx02.eternal-september.org;
 posting-host="d7777aaea4e05f5460ede15b9236d665";
	logging-data="14605"; mail-complaints-to="abuse@eternal-september.org";
	posting-account="U2FsdGVkX18cTK0WT7aoBr7IMyZ2tpGJFw5jUv5rUYo="
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:45.0)
 Gecko/20100101 Thunderbird/45.5.1
In-Reply-To: <o2rfan$f4$1@gioia.aioe.org>
Cancel-Lock: sha1:Yq5wxqHaDDSLID/UWqQWY5F6xpI=
Xref: news.eternal-september.org comp.lang.ada:32821
Date: 2016-12-14T17:31:34+01:00
List-Id: <comp.lang.ada>

On 14/12/2016 13:52, Dmitry A. Kazakov wrote:
> On 14/12/2016 13:44, G.B. wrote:
>> On 14/12/2016 12:25, Dmitry A. Kazakov wrote:
>>
>>> That is the problem with implied contracts. Is this legal:
>>>
>>> begin
>>>    loop
>>>       X (Read (Stream));
>>>    end loop;
>>> exception
>>>    when Constraint_Error =>
>>>       null;
>>> end;
>>
>>    "Assertions are not an input checking mechanism"
>>    "To avoid a common misunderstanding, make sure to note
>> that each of the contracts discussed holds between a routine
>> (the supplier) and another routine (its caller): we are concerned
>> about software-to-software communication, not software-to-human
>> or software-to-outside-world. (...) Here there is no substitute
>> for the usual condition-checking constructs, include the venerable
>> IF ... THEN ...; the exception handling mechanism ... may also be
>> helpful ". [1]
>>
>> [1] Meyer, Bertrand: OOSC2, 2nd ed, §11.6
>
> Is it legal or not?

Like you have said, "It is about formal language-supported contracts
and all sorts of other contracts". So, I think there is enough material
there to conclude that this kind or that kind of contract should
be legally dominating a particular program design decision.