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From: "G.B." <bauhaus@notmyhomepage.invalid>
Newsgroups: comp.lang.ada
Subject: Re: Ada 2012 Constraints (WRT an Ada IR)
Date: Wed, 14 Dec 2016 13:44:04 +0100
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Xref: news.eternal-september.org comp.lang.ada:32815
Date: 2016-12-14T13:44:04+01:00
List-Id: <comp.lang.ada>

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