From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Ada and software testing
Date: Wed, 14 Jul 2021 21:51:54 +0200 [thread overview]
Message-ID: <scnf8n$1lgd$1@gioia.aioe.org> (raw)
In-Reply-To: 87pmvky9lz.fsf@nightsong.com
On 2021-07-14 21:32, Paul Rubin wrote:
> I do have to say that errors thrown by runtime checks on range types are
> still program bugs,
No, it depends on the contract.
> in the sense that they are type errors,
A type error cannot happen at run-time per definition of strong typing.
Constraint violation is not a type error.
> that in
> principle we should want to catch at compile time.
If you can. In reality it is impossible to enforce validity per type
system, because such contracts are often not enforceable.
So the trick is to relax the contract by including exceptions, which is
what Ada constrained subtypes do. But then Constraint_Error becomes a
legal "value" function + would "return" on overflow.
--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
next prev parent reply other threads:[~2021-07-14 19:51 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-12 0:49 Ada and software testing Paul Rubin
2021-07-12 8:40 ` Dmitry A. Kazakov
2021-07-14 19:56 ` Paul Rubin
2021-07-12 16:14 ` Gautier write-only address
2021-07-12 16:41 ` Dmitry A. Kazakov
2021-07-14 19:32 ` Paul Rubin
2021-07-14 19:51 ` Dmitry A. Kazakov [this message]
2021-07-14 20:02 ` Paul Rubin
2021-07-15 7:27 ` Dmitry A. Kazakov
2021-07-16 10:01 ` G.B.
2021-07-16 10:21 ` Paul Rubin
2021-07-28 15:28 ` Paul Butcher
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