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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Ada 2012 Constraints (WRT an Ada IR)
Date: Fri, 9 Dec 2016 10:38:37 +0100
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Xref: news.eternal-september.org comp.lang.ada:32697
Date: 2016-12-09T10:38:37+01:00
List-Id: <comp.lang.ada>

On 08/12/2016 19:35, G.B. wrote:
> On 08.12.16 11:03, Dmitry A. Kazakov wrote:
>>> What will these two parts look like in the example,
>>> bothrelating to "+", and to Plus?
>>>
>>> procedure Plus is
>>>    Y : Standard.Integer := Standard.Integer'Last;
>>> begin
>>>    Y := Y + 1;
>>> end Plus;
>>
>> The contract of Plus is can [or must] raise Constraint_Error.
>>
>> If the client will prove absence of Constraint_Error it must handle
>> that anytime Plus is called.
>
> So, the following function will also just announce that
> it can raise Constraint_Error?
>
> function Plus_Too (A, B: Standard.Integer)
>                   return Standard.Integer is
> begin
>    return A + B;
> end Plus_Too;

At least. Contracts have different precision of the post-condition:

1.    Constraint_Error
    or none

2.    Constraint_Error when combination of argument values
    or none

3.    Constraint_Error when combination of argument values
    or 0 when combination of argument values
    or 1 when combination of argument values
    ...

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