From: Tim Rowe <spamtrap@tgrowe.plus.net>
Subject: Re: Newbie question: SPARK verification condition on member of private record
Date: Fri, 03 Apr 2009 00:58:10 +0100
Date: 2009-04-03T00:58:10+01:00 [thread overview]
Message-ID: <y7ednbO7TLaJzEjUnZ2dnUVZ8sSdnZ2d@posted.plusnet> (raw)
In-Reply-To: <XQOei4CZgN1JJw9Y@diphi.demon.co.uk>
JP Thornley wrote:
> The usual recommendation for updating records is to assign an aggregate
> rather than individual components (this gets rid of all the
> upf_/update's), but the need to update an element of the array makes it
> more awkward in this case.
Yes, an aggregate assignment followed by the update of the array makes
for a much worse set of things to prove.
> That's a lot easier than the usual way (banging head against desk until
> you eventually realise that it's not a problem with the tools).
But less entertaining for bystanders.
In fact, in this case I wouldn't have noticed anything wrong. When
specifying that all original members of the array would be unchanged, I
accidentally appended a tilde to "This" on /both/ sides of the identity,
so it was trivially true. It would probably have vanished in the
simplifier, and I wouldn't have known anything was wrong. Thank goodness
for peer review and testing in the Real World! (And the low likelihood
of a typing error in the annotation aligning with a corresponding error
in code).
next prev parent reply other threads:[~2009-04-02 23:58 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-01 19:38 Newbie question: SPARK verification condition on member of private record Tim Rowe
2009-04-01 21:04 ` JP Thornley
2009-04-01 23:50 ` Tim Rowe
2009-04-02 9:00 ` JP Thornley
2009-04-02 12:00 ` Tim Rowe
2009-04-02 15:22 ` JP Thornley
2009-04-02 18:09 ` roderick.chapman
2009-04-03 11:26 ` Tim Rowe
2009-04-02 23:58 ` Tim Rowe [this message]
2009-04-03 13:36 ` JP Thornley
2009-04-06 11:49 ` Tim Rowe
replies disabled
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox