From: "Matthew Heaney" <matthew_heaney@acm.org>
Subject: Re: 'constant functions' and access constant params (was Re: Array of Variant Records Question...)
Date: 1999/09/23
Date: 1999-09-23T00:00:00+00:00 [thread overview]
Message-ID: <37ea53fe@news1.prserv.net> (raw)
In-Reply-To: 37E9B259.7C58@l5i.net
In article <37E9B259.7C58@l5i.net> , Vincent Marciante <ma4rciant@l5i.net>
wrote:
> Would the following (or similar) also require consideration?
> Doesn't it also exhibit a loophole? If not, why not?
We were only talking about state changes that violate the terms of the
contract between client and supplier (although Richard and I do not agree on
the exact nature of that contract).
Your example illustrates the point I was trying to make: the postcondition
is "formal.ref1.all = old formal.ref1.all + 1", and the subprogram does
indeed satisfy that postcondition. Here, the state is completely public,
but no illicit state changes have taken place other that what were promised.
I suppose if you wanted to be completely doctrinaire you could pass Formal
as an in-out mode parameter, but I don't recommend this. It's no secret
that Formal is a record the contains access objects, and that the function
inc_formal_ref1_object modifies the value designated by the access object,
not the access object itself. So just pass Formal as in-mode.
Your function does exactly what it promised to do: nothing more, and nothing
less. So as far as I am concerned, there is no problem with it.
--
Those who believe in the supernatural should be required to learn computer
programming. This would force them to discover that things which appear to
be completely mysterious and incomprehensible, in fact have a logical, and
usually simple, explanation.
J. B. R. Yant, Mortal Words
next prev parent reply other threads:[~1999-09-23 0:00 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-09-08 0:00 Array of Variant Records Question Bruce Detter
1999-09-08 0:00 ` Thank you Bruce Detter
1999-09-08 0:00 ` Martin C. Carlisle
1999-09-08 0:00 ` Array of Variant Records Question Martin C. Carlisle
1999-09-08 0:00 ` Ted Dennison
1999-09-08 0:00 ` Matthew Heaney
1999-09-08 0:00 ` Mike Silva
1999-09-08 0:00 ` Matthew Heaney
1999-09-09 0:00 ` Robert Dewar
1999-09-09 0:00 ` Matthew Heaney
1999-09-09 0:00 ` Matthew Heaney
1999-09-09 0:00 ` Mark Lundquist
1999-09-09 0:00 ` Robert Dewar
1999-09-09 0:00 ` Robert Dewar
1999-09-09 0:00 ` Brian Rogoff
1999-09-13 0:00 ` Matthew Heaney
1999-09-13 0:00 ` Robert A Duff
1999-09-13 0:00 ` Matthew Heaney
1999-09-13 0:00 ` Brian Rogoff
1999-09-14 0:00 ` Robert Dewar
1999-09-14 0:00 ` Robert Dewar
1999-09-14 0:00 ` Brian Rogoff
1999-09-09 0:00 ` Matthew Heaney
1999-09-10 0:00 ` Robert Dewar
1999-09-10 0:00 ` Mark Lundquist
1999-09-10 0:00 ` Matthew Heaney
1999-09-11 0:00 ` Jean-Pierre Rosen
1999-09-14 0:00 ` "cast away const" (was Re: Array of Variant Records Question...) Mark Lundquist
[not found] ` <wccd7viiv59.fsf@world.std.com>
1999-09-22 0:00 ` Array of Variant Records Question Robert I. Eachus
[not found] ` <7rrmqd$l89@drn.newsguy.com>
[not found] ` <wcciu59n2uf.fsf@world.std.com>
1999-09-22 0:00 ` Robert I. Eachus
1999-09-23 0:00 ` Robert Dewar
1999-09-23 0:00 ` Robert I. Eachus
1999-09-10 0:00 ` Mark Lundquist
1999-09-10 0:00 ` Matthew Heaney
1999-09-11 0:00 ` Robert Dewar
1999-09-11 0:00 ` Richard D Riehle
1999-09-13 0:00 ` Hyman Rosen
1999-09-14 0:00 ` Mark Lundquist
[not found] ` <7roohh$s6r@dfw-ixnews7.ix.netcom.com>
[not found] ` <37e01168@news1.prserv.net>
[not found] ` <7rp86o$c6h@dfw-ixnews3.ix.netcom.com>
[not found] ` <37E18CC6.C8D431B@rational.com>
[not found] ` <7rs8bn$s6@dfw-ixnews4.ix.netcom.com>
[not found] ` <37e2e58c@news1.prserv.net>
1999-09-22 0:00 ` 'constant functions' and access constant params (was Re: Array of Variant Records Question...) Richard D Riehle
1999-09-22 0:00 ` Mark Lundquist
1999-09-22 0:00 ` Mark Lundquist
1999-09-22 0:00 ` Matthew Heaney
1999-09-22 0:00 ` Richard D Riehle
1999-09-22 0:00 ` Matthew Heaney
1999-09-22 0:00 ` Matthew Heaney
1999-09-23 0:00 ` Vincent Marciante
1999-09-23 0:00 ` Matthew Heaney [this message]
1999-09-24 0:00 ` Robert A Duff
1999-09-25 0:00 ` Matthew Heaney
1999-09-27 0:00 ` Richard D Riehle
1999-09-27 0:00 ` Richard D Riehle
1999-09-27 0:00 ` David Kristola
1999-09-23 0:00 ` Robert Dewar
1999-09-27 0:00 ` Richard D Riehle
1999-09-28 0:00 ` Robert Dewar
1999-09-28 0:00 ` "Competence" (was: 'constant functions' and access constant params) Ted Dennison
1999-09-28 0:00 ` Robert Dewar
1999-09-28 0:00 ` 'constant functions' and access constant params (was Re: Array of Variant Records Question...) Robert Dewar
1999-09-28 0:00 ` Richard D Riehle
1999-09-29 0:00 ` Robert A Duff
1999-09-29 0:00 ` Robert Dewar
[not found] ` <wccemfxn15s.fsf@world.std.com>
1999-09-22 0:00 ` Richard D Riehle
1999-09-10 0:00 ` Proposed Ada features " Mark Lundquist
1999-09-10 0:00 ` Matthew Heaney
1999-09-10 0:00 ` tmoran
1999-09-09 0:00 ` Array of Variant Records Question Nick Roberts
1999-09-09 0:00 ` Tucker Taft
1999-09-10 0:00 ` Nick Roberts
1999-09-09 0:00 ` Robert Dewar
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