From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Efficient Sequential Access to Arrays
Date: Thu, 26 Jul 2012 15:46:04 +0200
Date: 2012-07-26T15:46:04+02:00 [thread overview]
Message-ID: <1d20andzhb0rk.ytxhpkza8tky$.dlg@40tude.net> (raw)
In-Reply-To: bbb593dd-253b-4a34-9123-cd2cec09f285@googlegroups.com
On Thu, 26 Jul 2012 05:32:32 -0700 (PDT), Keean Schupke wrote:
> So if I do
>
> if X'Valid then
> Y(X) -- if X is the same type as the index of Y then no need to range check.
> end if
>
> If I explicitly check 'Valid, the compiler should be able to omit some
> implicit range checks, as 'Valid is an explicit range check.
No. You do it this way:
declare
subtype Y_Index is Integer range Y'Range;
Safe_X : Y_Index := X;
begin
... Y (Safe_X) ... -- The compiler has here information to
-- eliminate check, though not required to
end;
P.S. The attribute 'Valid is used when there is a danger that the compiler
hasn't checked the argument for whatever reason. Usually it is after
Unchecked_Conversion.
Some would disagree, but IMO in a well-written Ada program you should never
ever need 'Valid. Don't do Unchecked_Conversion with doubtful outcome.
Don't use stream attributes for constrained types. Don't use for X'Address
use Z'Address for the purpose of conversion etc.
--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
next prev parent reply other threads:[~2012-08-01 2:50 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-15 18:40 Efficient Sequential Access to Arrays Keean Schupke
2012-07-15 19:48 ` Dmitry A. Kazakov
2012-07-15 20:03 ` Keean Schupke
2012-07-15 20:56 ` Keean Schupke
2012-07-16 11:34 ` Jacob Sparre Andersen
2012-07-15 21:05 ` tmoran
2012-07-15 21:08 ` Keean Schupke
2012-07-16 1:19 ` tmoran
2012-07-15 21:44 ` Georg Bauhaus
2012-07-16 7:47 ` Dmitry A. Kazakov
2012-07-16 10:16 ` Keean Schupke
2012-07-16 14:57 ` Dmitry A. Kazakov
2012-07-16 16:39 ` Keean Schupke
2012-07-16 17:02 ` Georg Bauhaus
2012-07-16 18:48 ` Dmitry A. Kazakov
2012-07-16 19:12 ` Keean Schupke
2012-07-17 6:31 ` Dmitry A. Kazakov
2012-07-17 6:50 ` Georg Bauhaus
2012-07-17 8:42 ` Dmitry A. Kazakov
2012-07-17 7:24 ` Keean Schupke
2012-07-16 19:43 ` John B. Matthews
2012-07-16 20:44 ` Keean Schupke
2012-07-16 22:23 ` tmoran
2012-07-17 6:40 ` Keean Schupke
2012-07-17 9:01 ` Dmitry A. Kazakov
2012-07-18 8:10 ` Keean Schupke
2012-07-18 18:11 ` tmoran
2012-07-19 10:41 ` Keean Schupke
2012-07-19 11:18 ` Georg Bauhaus
2012-07-19 19:58 ` Keean Schupke
2012-07-21 8:24 ` Keean Schupke
2012-07-21 11:52 ` Georg Bauhaus
2012-07-21 16:14 ` Keean Schupke
2012-07-21 17:09 ` Keean Schupke
[not found] ` <i78m081tccmp078spmsei1l5vnj3k0kbkj@invalid.netcom.com>
2012-07-22 15:50 ` Keean Schupke
2012-07-22 5:13 ` Shark8
2012-07-15 21:35 ` J-P. Rosen
2012-07-15 19:52 ` Shark8
2012-07-15 20:16 ` Keean Schupke
2012-07-15 21:33 ` Georg Bauhaus
2012-07-17 18:16 ` Florian Weimer
2012-07-22 10:01 ` robin.vowels
2012-07-30 6:31 ` Jacob Sparre Andersen
2012-07-30 7:16 ` Keean Schupke
2012-07-30 9:20 ` Georg Bauhaus
2012-07-30 14:04 ` Keean Schupke
2012-07-22 10:09 ` robin.vowels
2012-07-22 16:02 ` Keean Schupke
2012-07-22 16:21 ` Florian Weimer
2012-07-22 16:46 ` Keean Schupke
2012-07-22 18:41 ` Florian Weimer
2012-07-24 8:21 ` Keean Schupke
2012-07-22 17:34 ` Niklas Holsti
2012-07-22 18:21 ` Keean Schupke
2012-07-30 14:18 ` Jacob Sparre Andersen
2012-07-24 16:00 ` robin.vowels
2012-07-25 7:09 ` Niklas Holsti
2012-07-25 9:03 ` Keean Schupke
2012-07-26 0:15 ` Randy Brukardt
2012-07-26 8:38 ` Keean Schupke
2012-07-26 10:10 ` Brian Drummond
2012-07-26 12:32 ` Keean Schupke
2012-07-26 13:46 ` Dmitry A. Kazakov [this message]
2012-07-26 17:40 ` Shark8
2012-07-26 18:56 ` Dmitry A. Kazakov
2012-07-27 5:25 ` Shark8
2012-07-27 6:28 ` Dmitry A. Kazakov
2012-07-27 7:01 ` Vasiliy Molostov
2012-07-27 8:48 ` Dmitry A. Kazakov
2012-07-27 12:01 ` Georg Bauhaus
2012-07-27 16:49 ` Vasiliy Molostov
2012-07-27 19:38 ` Dmitry A. Kazakov
2012-07-28 5:32 ` Shark8
2012-07-28 7:37 ` Dmitry A. Kazakov
2012-07-28 18:32 ` Shark8
[not found] ` <6ov218tnkbqu3vpkuo4t77rd7de0a3aesf@invalid.netcom.com>
2012-07-26 18:49 ` Dmitry A. Kazakov
[not found] ` <86d31898ne39maimbl24knds7rf38qg7vc@invalid.netcom.com>
2012-07-27 6:45 ` Dmitry A. Kazakov
2012-07-27 8:21 ` Keean Schupke
2012-07-27 8:50 ` Dmitry A. Kazakov
2012-07-27 9:17 ` Keean Schupke
2013-02-25 21:18 ` Eryndlia Mavourneen
2012-07-26 13:08 ` Georg Bauhaus
2012-07-26 19:37 ` stefan-lucks
2012-07-26 19:21 ` stefan-lucks
2012-07-31 3:12 ` Randy Brukardt
2012-07-26 7:11 ` Markus Schöpflin
2012-07-26 14:47 ` Robin Vowels
2012-07-26 15:18 ` Martin
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