From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Ada.Strings.Bounded
Date: Mon, 14 Apr 2008 10:00:04 +0200
Date: 2008-04-14T10:00:04+02:00 [thread overview]
Message-ID: <1oezq4ijzah23.18y7fwriuqe6s.dlg@40tude.net> (raw)
In-Reply-To: 0a2bbbb1-19d8-41d3-84a0-321cd045a48b@1g2000prf.googlegroups.com
On Sun, 13 Apr 2008 16:52:00 -0700 (PDT), Eric Hughes wrote:
> Speaking formally, which I was trying to do (but failing in the
> details), almost-a-string is a subset of not-a-string. Axiom
> satisfaction has sharp boundaries that don't usually coincide with
> ordinary conceptual boundaries. Informally, sure, they're both
> strings. But the Ada String type, with its padding, does not satisfy
> the axioms of universal_string. The problem is that it's a fixed
> array, not a fixed array allocation with a variable length like
> Bounded_String. If I assign the value "A", a String of length 1, to a
> String(2), the length of its value as a universal_string changes from
> 1 to 2. So even simple assignment violates the axioms.
If we had universal_string, it would have no assignment anyway, because all
universal objects are immutable.
There is a difference between types and their constrained subtypes in terms
of substitutability. That's why the language has Constraint_Error defined.
The contracts extended by Constraint_Error aren't violated and everything
is fine.
> The problem that was the nexus of the original discussion is that
> string literals are of type String and not deemed elements of
> universal_string.
I don't see any harm here. You cannot assign literals.
BTW, there are funny language rules which prevent things like this:
type Integer is range -5..5; -- On some tiny machine
L : constant := ("abcd" & "defg" & "defg")'Length / 3;
-- Illegal anyway
So you cannot exploit the limitation of the string index being Positive in
order to construct strings longer than the index at compile time.
--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
next prev parent reply other threads:[~2008-04-14 8:00 UTC|newest]
Thread overview: 108+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-31 22:44 Untyped Ada? Phaedrus
2008-04-01 0:16 ` Randy Brukardt
2008-04-01 7:19 ` tmoran
2008-04-01 7:44 ` Dmitry A. Kazakov
2008-04-01 8:28 ` Jean-Pierre Rosen
2008-04-01 21:44 ` Phaedrus
2008-04-01 21:51 ` Ludovic Brenta
2008-04-01 17:09 ` Pascal Obry
2008-04-01 22:00 ` Phaedrus
2008-04-02 7:31 ` Dmitry A. Kazakov
2008-04-04 15:16 ` Graham
2008-04-04 16:10 ` Pascal Obry
2008-04-04 21:09 ` Ada.Bounded_Strings Adam Beneschan
2008-04-04 21:15 ` Ada.Strings.Bounded Adam Beneschan
2008-04-05 4:39 ` Ada.Strings.Bounded Gautier
2008-04-05 9:43 ` Ada.Strings.Bounded Pascal Obry
2008-04-05 10:10 ` Ada.Strings.Bounded Dmitry A. Kazakov
2008-04-05 11:36 ` Ada.Strings.Bounded Gautier
2008-04-05 12:14 ` Ada.Strings.Bounded Pascal Obry
2008-04-06 0:31 ` Ada.Strings.Bounded Randy Brukardt
2008-04-07 14:57 ` Ada.Strings.Bounded Adam Beneschan
2008-04-07 15:23 ` Ada.Strings.Bounded Dmitry A. Kazakov
2008-04-07 16:34 ` Ada.Strings.Bounded stefan-lucks
2008-04-07 17:34 ` Ada.Strings.Bounded (see below)
2008-04-12 18:50 ` Ada.Strings.Bounded Eric Hughes
2008-04-12 19:46 ` Ada.Strings.Bounded Georg Bauhaus
2008-04-13 16:53 ` Ada.Strings.Bounded Eric Hughes
2008-04-13 20:10 ` Ada.Strings.Bounded Robert A Duff
2008-04-13 23:52 ` Ada.Strings.Bounded Eric Hughes
2008-04-14 8:00 ` Dmitry A. Kazakov [this message]
2008-04-14 15:25 ` Ada.Strings.Bounded Eric Hughes
2008-04-14 18:36 ` Ada.Strings.Bounded Dmitry A. Kazakov
2008-04-15 1:39 ` Ada.Strings.Bounded Eric Hughes
2008-04-12 21:09 ` Ada.Strings.Bounded Dmitry A. Kazakov
2008-04-13 16:31 ` Ada.Strings.Bounded Eric Hughes
2008-04-13 20:02 ` Ada.Strings.Bounded Robert A Duff
2008-04-13 23:20 ` Ada.Strings.Bounded Eric Hughes
2008-04-14 9:07 ` Ada.Strings.Bounded Dmitry A. Kazakov
2008-04-14 15:50 ` Ada.Strings.Bounded Eric Hughes
2008-04-14 18:52 ` Ada.Strings.Bounded Dmitry A. Kazakov
2008-04-15 2:07 ` Ada.Strings.Bounded Eric Hughes
2008-04-15 8:02 ` Ada.Strings.Bounded Dmitry A. Kazakov
2008-04-15 14:20 ` Ada.Strings.Bounded Eric Hughes
2008-04-15 15:23 ` Ada.Strings.Bounded Dmitry A. Kazakov
2008-04-16 2:51 ` Ada.Strings.Bounded Eric Hughes
2008-04-16 8:00 ` Ada.Strings.Bounded Dmitry A. Kazakov
[not found] ` <bc3a8b4e-63fe-47a6-b10b-7056f6d7d586@w5g2000prd.googlegroups.com>
2008-04-15 14:58 ` Ada.Strings.Bounded Dmitry A. Kazakov
2008-04-16 2:46 ` Ada.Strings.Bounded Eric Hughes
2008-04-16 8:16 ` Ada.Strings.Bounded Dmitry A. Kazakov
2008-04-16 14:40 ` Ada.Strings.Bounded Eric Hughes
2008-04-16 18:28 ` Ada.Strings.Bounded Dmitry A. Kazakov
2008-04-21 0:44 ` Ada.Strings.Bounded Eric Hughes
2008-04-21 14:08 ` Ada.Strings.Bounded Robert A Duff
2008-04-21 16:35 ` Ada.Strings.Bounded Eric Hughes
2008-04-21 18:04 ` Ada.Strings.Bounded Robert A Duff
2008-04-22 0:19 ` Ada.Strings.Bounded Eric Hughes
2008-04-22 0:49 ` Ada.Strings.Bounded Adam Beneschan
2008-04-22 1:02 ` Ada.Strings.Bounded Adam Beneschan
2008-04-22 15:30 ` Ada.Strings.Bounded Eric Hughes
2008-04-22 16:08 ` Ada.Strings.Bounded Robert A Duff
2008-04-22 15:25 ` Ada.Strings.Bounded Eric Hughes
2008-04-22 15:54 ` Ada.Strings.Bounded Robert A Duff
2008-04-22 15:41 ` Ada.Strings.Bounded Robert A Duff
2008-04-22 17:49 ` Ada.Strings.Bounded Dmitry A. Kazakov
2008-04-22 18:26 ` Ada.Strings.Bounded Samuel Tardieu
2008-04-22 18:59 ` Ada.Strings.Bounded Dmitry A. Kazakov
2008-04-22 18:47 ` Ada.Strings.Bounded Eric Hughes
2008-04-22 19:19 ` Ada.Strings.Bounded Dmitry A. Kazakov
2008-04-22 19:41 ` Ada.Strings.Bounded Robert A Duff
2008-04-22 22:55 ` Ada.Strings.Bounded Eric Hughes
2008-04-23 6:40 ` Ada.Strings.Bounded christoph.grein
2008-04-23 6:54 ` Ada.Strings.Bounded christoph.grein
2008-04-23 10:42 ` Ada.Strings.Bounded Georg Bauhaus
2008-04-23 12:32 ` Ada.Strings.Bounded Dmitry A. Kazakov
2008-04-23 12:52 ` Ada.Strings.Bounded christoph.grein
2008-04-23 13:34 ` Ada.Strings.Bounded Georg Bauhaus
2008-04-23 15:12 ` Ada.Strings.Bounded Adam Beneschan
2008-04-23 15:36 ` Ada.Strings.Bounded (see below)
2008-04-23 17:09 ` Ada.Strings.Bounded Ray Blaak
2008-04-24 0:29 ` Ada.Strings.Bounded Randy Brukardt
2008-04-22 20:15 ` Ada.Strings.Bounded Adam Beneschan
2008-04-23 13:14 ` Ada.Strings.Bounded Peter Hermann
2008-04-23 14:40 ` Ada.Strings.Bounded Dmitry A. Kazakov
2008-04-23 15:03 ` Ada.Strings.Bounded Adam Beneschan
2008-04-22 19:56 ` Ada.Strings.Bounded Adam Beneschan
2008-04-21 18:50 ` Ada.Strings.Bounded Dmitry A. Kazakov
2008-04-22 0:31 ` Ada.Strings.Bounded Eric Hughes
2008-04-14 15:11 ` Ada.Strings.Bounded Adam Beneschan
2008-04-14 16:09 ` Ada.Strings.Bounded Eric Hughes
2008-04-14 18:13 ` Ada.Strings.Bounded Georg Bauhaus
2008-04-15 1:35 ` Ada.Strings.Bounded Eric Hughes
2008-04-15 20:33 ` Ada.Strings.Bounded Georg Bauhaus
2008-04-16 3:11 ` Ada.Strings.Bounded Eric Hughes
2008-04-04 23:35 ` Ada.Bounded_Strings Robert A Duff
2008-04-05 1:46 ` Ada.Bounded_Strings Adam Beneschan
2008-04-05 4:55 ` Ada.Bounded_Strings Randy Brukardt
2008-04-05 7:30 ` Ada.Bounded_Strings Dmitry A. Kazakov
2008-04-06 0:44 ` Ada.Bounded_Strings Randy Brukardt
2008-04-04 16:18 ` Untyped Ada? Adam Beneschan
2008-04-04 16:32 ` DScott
2008-04-04 17:38 ` Dmitry A. Kazakov
2008-04-04 18:52 ` Georg Bauhaus
2008-04-05 8:07 ` Dmitry A. Kazakov
2008-04-04 19:14 ` Graham
2008-04-04 21:06 ` tmoran
2008-04-05 8:44 ` Dmitry A. Kazakov
2008-04-12 16:50 ` Eric Hughes
2008-04-04 18:02 ` adaworks
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