From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Subtypes and type invariants in Ada2012
Date: Mon, 21 Aug 2017 18:18:27 +0200
Date: 2017-08-21T18:18:27+02:00 [thread overview]
Message-ID: <onf14l$9uv$1@gioia.aioe.org> (raw)
In-Reply-To: oneuqr$5l9$1@gioia.aioe.org
On 2017-08-21 17:38, Victor Porton wrote:
> So, my question: Is it possible to restrict a subtype with something like a
> type invariant?
Type invariant is not a restriction of public interface/properties, it
is an implementation detail. So it should never produce a [sub]type.
> I want a subtype restricted by an arbitrary condition. Is it possible?
Arbitrary condition breaks type operations. E.g. condition Is_Prime (X)
breaks more or less everything (assuming covariance). All restrictions
do. A few don't break much, e.g. range constraints.
--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
next prev parent reply other threads:[~2017-08-21 16:18 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-21 15:38 Subtypes and type invariants in Ada2012 Victor Porton
2017-08-21 16:10 ` J-P. Rosen
2017-08-21 16:18 ` Dmitry A. Kazakov [this message]
2017-08-21 16:29 ` Victor Porton
2017-08-21 16:52 ` Dmitry A. Kazakov
2017-08-21 17:41 ` Victor Porton
2017-08-21 19:55 ` Dmitry A. Kazakov
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