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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: about the new Ada 2012 pre/post conditions
Date: Sat, 23 Jun 2012 13:01:17 +0200
Organization: cbb software GmbH
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Date: 2012-06-23T13:01:17+02:00
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On Sat, 23 Jun 2012 12:46:56 +0200, Georg Bauhaus wrote:

> On 23.06.12 01:08, Dmitry A. Kazakov wrote:
>>> And Ada*always*  has had dynamic preconditions:
>>> >
>>> >       procedure New_Line (Spacing : in Positive_Count := 1);
>> The precondition here is Spacing in Positive_Count'Base because the
>> behavior of New_Line is*defined*  when Spacing is not in
>> Positive_Count'Range.
>>
>>     New_Line(0)
>>
>> is a*legal*  Ada program.
>   
> The behavior of New_Line is not relevant,

It is OK if New_Line(0) would reboot the computer?

New_Line(0) is not straight legal, it not an error in the classification of
errors (RM 1.1.5).

Compare: a contract violation is an *unbounded ERROR*.

Aside. If you could estimate the effect of a contract violation, in order
to make the case for a bounded error, that would not save the idea of
checking either. Because, of course, in that case you also could detect the
violation itself, which is a much simpler task than tracking all possible
consequences down.

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