From: Georg Bauhaus <rm.dash-bauhaus@futureapps.de>
Subject: Re: about the new Ada 2012 pre/post conditions
Date: Tue, 26 Jun 2012 18:48:05 +0200
Date: 2012-06-26T18:48:05+02:00 [thread overview]
Message-ID: <4fe9e7c5$0$6567$9b4e6d93@newsspool4.arcor-online.net> (raw)
In-Reply-To: <z27igg6796oj$.oefrs9mmhzok$.dlg@40tude.net>
On 26.06.12 16:45, Dmitry A. Kazakov wrote:
> On Tue, 26 Jun 2012 15:49:24 +0200, Georg Bauhaus wrote:
>
>> On 26.06.12 15:07, Dmitry A. Kazakov wrote:
>>
>>> They are contracts when checked statically and implementations when checked
>>> dynamically.
>>
>> What do pre/post implement, if so, in your view?
>
> if Pre(...) then
> <body>
> if Post(...) then
> null;
> else
> raise Constraint_Error;
> end if;
> else
> raise Constraint_Error;
> end if;
There is a different understanding of "implement". Pre/Post
do not implement anything essential. <body> is supposed to
implement something that essentially agrees with Pre/Post.
Some confusion here, I think.
>>> Contract violation => terminate. Exceptional state => recover.
>>
>> How does a client do make the program recover if an exception
>> stands for "unforeseen"?
>
> How does a client recover if X contains 3 rather than 1?
>
> Answer: it recovers by continuing its program further.
In a truly exceptional situation, as opposed to when there is
a catch-all "special value", there is no contract that could have
been violated, because the contract does not in any way cover the
situation There is no known good value contained in X, for example,
because there is no (practically) meaningful state.
For this truly exceptional situation, which is necessarily
unforeseen (otherwise it could have been covered by the contract),
I'd include
Exception(foreseeable) => recover.
Exception(unforeseen) => STOP.
Unforeseen is a modest word for "the exception handling mechanism
might be broken in this situation". However, Exception(foreseeable)
would include violations of Ada-Pre/Ada-Post, unless checking these
results in Exception(unforeseeable).
next prev parent reply other threads:[~2012-06-26 16:48 UTC|newest]
Thread overview: 125+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-20 13:39 about the new Ada 2012 pre/post conditions Nasser M. Abbasi
2012-06-20 14:02 ` Georg Bauhaus
2012-06-20 14:13 ` Dmitry A. Kazakov
2012-06-20 14:24 ` Nasser M. Abbasi
2012-06-20 14:37 ` Dmitry A. Kazakov
2012-06-20 17:02 ` Georg Bauhaus
2012-06-20 18:28 ` Dmitry A. Kazakov
2012-06-21 20:32 ` Randy Brukardt
2012-06-22 7:23 ` Dmitry A. Kazakov
2012-06-22 11:54 ` Georg Bauhaus
2012-06-22 12:39 ` Georg Bauhaus
2012-06-22 12:43 ` Dmitry A. Kazakov
2012-06-22 14:30 ` Georg Bauhaus
2012-06-22 14:36 ` Georg Bauhaus
2012-06-22 15:05 ` Dmitry A. Kazakov
2012-06-22 15:52 ` Georg Bauhaus
2012-06-22 16:35 ` Dmitry A. Kazakov
2012-06-22 16:53 ` Georg Bauhaus
2012-06-22 16:45 ` Georg Bauhaus
2012-06-22 17:24 ` Dmitry A. Kazakov
2012-06-22 19:41 ` Randy Brukardt
2012-06-22 23:08 ` Dmitry A. Kazakov
2012-06-23 10:46 ` Georg Bauhaus
2012-06-23 11:01 ` Dmitry A. Kazakov
2012-06-23 17:46 ` AdaMagica
2012-06-23 19:23 ` Dmitry A. Kazakov
2012-06-24 14:59 ` Georg Bauhaus
2012-06-24 16:06 ` Dmitry A. Kazakov
2012-06-24 19:51 ` Georg Bauhaus
2012-06-25 7:48 ` Dmitry A. Kazakov
2012-06-25 10:10 ` Georg Bauhaus
2012-06-25 8:08 ` Dmitry A. Kazakov
2012-06-25 10:17 ` Georg Bauhaus
2012-06-25 11:54 ` Dmitry A. Kazakov
2012-06-25 12:39 ` Georg Bauhaus
2012-06-25 12:51 ` Georg Bauhaus
2012-06-25 13:19 ` Dmitry A. Kazakov
2012-06-25 16:43 ` Georg Bauhaus
2012-06-25 14:08 ` stefan-lucks
2012-06-25 14:36 ` Dmitry A. Kazakov
2012-06-25 14:37 ` Dmitry A. Kazakov
2012-06-25 16:26 ` stefan-lucks
2012-06-25 19:42 ` Dmitry A. Kazakov
2012-06-26 11:50 ` stefan-lucks
2012-06-26 13:07 ` Dmitry A. Kazakov
2012-06-26 13:49 ` Georg Bauhaus
2012-06-26 14:45 ` Dmitry A. Kazakov
2012-06-26 16:48 ` Georg Bauhaus [this message]
2012-06-26 19:43 ` Dmitry A. Kazakov
2012-06-27 8:23 ` Georg Bauhaus
2012-06-27 8:52 ` Dmitry A. Kazakov
2012-06-27 10:30 ` Georg Bauhaus
2012-06-27 12:19 ` Dmitry A. Kazakov
2012-06-27 13:41 ` Nasser M. Abbasi
2012-06-28 7:00 ` Georg Bauhaus
2012-06-27 15:08 ` Georg Bauhaus
2012-06-29 21:03 ` Shark8
2012-06-30 8:26 ` Dmitry A. Kazakov
2012-06-30 12:54 ` Niklas Holsti
2012-07-05 2:58 ` Shark8
2012-07-05 7:24 ` Dmitry A. Kazakov
2012-07-06 6:23 ` Shark8
2012-07-06 7:57 ` Dmitry A. Kazakov
2012-07-07 1:09 ` Randy Brukardt
2012-07-07 8:44 ` Dmitry A. Kazakov
2012-06-26 14:54 ` stefan-lucks
2012-06-26 15:14 ` Dmitry A. Kazakov
2012-07-03 5:28 ` Randy Brukardt
2012-07-03 12:53 ` Dmitry A. Kazakov
2012-07-03 13:48 ` Georg Bauhaus
2012-07-03 14:06 ` Dmitry A. Kazakov
2012-07-03 16:12 ` Georg Bauhaus
2012-07-03 16:45 ` Georg Bauhaus
2012-07-05 1:45 ` Randy Brukardt
2012-07-05 7:48 ` Dmitry A. Kazakov
2012-07-05 19:11 ` Adam Beneschan
2012-07-05 19:55 ` Dmitry A. Kazakov
2012-07-06 7:41 ` Georg Bauhaus
2012-07-06 7:47 ` Georg Bauhaus
2012-07-06 8:05 ` Dmitry A. Kazakov
2012-07-06 8:30 ` Georg Bauhaus
2012-07-06 9:01 ` Dmitry A. Kazakov
2012-07-06 11:33 ` Simon Wright
2012-07-06 13:25 ` Dmitry A. Kazakov
2012-07-06 12:07 ` Georg Bauhaus
2012-07-06 13:37 ` Dmitry A. Kazakov
2012-07-06 16:17 ` Georg Bauhaus
2012-07-06 16:34 ` Georg Bauhaus
2012-07-06 19:18 ` Dmitry A. Kazakov
2012-07-07 1:24 ` Randy Brukardt
2012-07-07 9:09 ` Dmitry A. Kazakov
2012-07-07 1:18 ` Randy Brukardt
2012-07-07 9:14 ` Dmitry A. Kazakov
2012-07-07 12:06 ` Georg Bauhaus
2012-07-07 12:54 ` Dmitry A. Kazakov
2012-07-07 13:31 ` Georg Bauhaus
2012-07-03 5:10 ` Randy Brukardt
2012-07-03 4:51 ` Randy Brukardt
2012-07-03 12:46 ` Dmitry A. Kazakov
2012-07-05 2:18 ` Randy Brukardt
2012-07-05 8:48 ` Dmitry A. Kazakov
2012-07-05 12:07 ` Georg Bauhaus
2012-07-05 12:13 ` Georg Bauhaus
2012-07-05 12:31 ` Dmitry A. Kazakov
2012-07-05 18:16 ` Georg Bauhaus
2012-07-05 19:57 ` Dmitry A. Kazakov
2012-07-06 6:53 ` Georg Bauhaus
2012-07-07 0:43 ` Randy Brukardt
2012-07-07 8:06 ` Dmitry A. Kazakov
2012-07-07 11:17 ` Georg Bauhaus
2012-07-07 11:31 ` Dmitry A. Kazakov
2012-07-07 12:21 ` Georg Bauhaus
2012-07-07 13:03 ` Dmitry A. Kazakov
2012-06-20 19:18 ` Anh Vo
2012-06-20 20:16 ` Jeffrey R. Carter
2012-06-20 20:21 ` Jeffrey R. Carter
2012-06-20 20:51 ` Maciej Sobczak
2012-06-20 21:04 ` Dmitry A. Kazakov
2012-06-20 22:19 ` Robert A Duff
2012-06-21 6:32 ` Georg Bauhaus
2012-06-21 20:37 ` Randy Brukardt
2012-06-21 20:55 ` Jeffrey Carter
2012-06-22 19:15 ` Randy Brukardt
2012-06-21 20:23 ` Randy Brukardt
2012-06-22 7:34 ` Martin
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