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From: "Randy Brukardt" <randy@rrsoftware.com>
Subject: Re: Ada 2012 Constraints (WRT an Ada IR)
Date: Mon, 5 Dec 2016 16:06:29 -0600
Date: 2016-12-05T16:06:29-06:00	[thread overview]
Message-ID: <o24ob9$v8q$1@franka.jacob-sparre.dk> (raw)
In-Reply-To: alpine.DEB.2.20.1612050922450.22845@debian

<Stefan.Lucks@uni-weimar.de> wrote in message 
news:alpine.DEB.2.20.1612050922450.22845@debian...
...
>On the other hand, there are systems, where a malfunction is worse than no
>function (e.g., a secure router -- better no communication than allowing
>attackers to pass through the security perimeter). In such cases, it may
>be wise do perform Assert-checking even in production executables.

My opinion is that the vast majority of systems are in this category, 
especially if one considers each task (here using "task" in its English 
meaning as a block of work) separately. Every system that I've personally 
worked on has been in this category (anti-spam filter - a bug causes a 
message to be quarantined, which provides a path to reproducing the bug; web 
server - a bug causes nothing useful to be returned, better than allowing a 
security hole and returning, say, a password file; Ada compiler - a bug 
usually causes the compiler to crash rather than producing incorrect code 
that might cause problems; Claw Builder - a bug usually causes buggy 
generated code, which breaks the contract with the user).

Most such systems need an "others" handler to ensure that one failing task 
(again, English meaning) doesn't cause the entire system to fail. Such 
handlers need some sort of reporting system so they're not silently covering 
bugs.

I also tend to disagree about suppressing/ignoring checks and predicates. In 
my experience, if a check or predicate or assertion is too expensive to run 
in the production system, it's also too expensive to run in testing. Simple 
checks should never be turned off -- a visible bug is always better than an 
invisible bug. (Moreover, compilers are always getting better about 
eliminating such checks, in which case many checks aren't made at all.) 
Expensive checks, if one has to have them at all, need to be managed 
separately from assertions/constraints/predicates -- one would only want to 
turn them on if all else has failed, and that clearly needs to be separate 
from the suppress/ignore mechanism. (Most of the systems I've worked on have 
a runtime management setup for tracing/assertions, where they get managed by 
functional areas as needed for figuring out the problem at hand.)

                             Randy.



  parent reply	other threads:[~2016-12-05 22:06 UTC|newest]

Thread overview: 195+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-11-28 23:49 Ada 2012 Constraints (WRT an Ada IR) Shark8
2016-11-29  8:17 ` G.B.
2016-11-29 20:32   ` Shark8
2016-11-29 20:44     ` Dmitry A. Kazakov
2016-11-29 20:51       ` Shark8
2016-11-29 21:06         ` Dmitry A. Kazakov
2016-11-29 22:59           ` Shark8
2016-11-30  8:31             ` Dmitry A. Kazakov
2016-11-30 18:28               ` Shark8
2016-11-30 20:26                 ` Niklas Holsti
2016-12-01  0:16                   ` Shark8
2016-12-01 22:15                     ` Randy Brukardt
2016-11-30 20:45                 ` Dmitry A. Kazakov
2016-12-01  0:58                   ` Shark8
2016-12-01  8:55                     ` Dmitry A. Kazakov
2016-12-01 22:26                       ` Randy Brukardt
2016-12-02 16:21                         ` Dmitry A. Kazakov
2016-12-02 19:15                           ` Randy Brukardt
2016-12-03 10:21                             ` Dmitry A. Kazakov
2016-12-02 19:50                           ` G.B.
2016-12-03 10:23                             ` Dmitry A. Kazakov
2016-12-03 14:02                               ` G.B.
2016-12-03 16:26                                 ` Dmitry A. Kazakov
2016-12-04 15:28                                   ` Robert Eachus
2016-12-05  8:41                                     ` Stefan.Lucks
2016-12-05  8:58                                       ` Dmitry A. Kazakov
2016-12-05 11:09                                         ` Simon Wright
2016-12-05 18:42                                           ` Shark8
2016-12-05 22:13                                             ` Dmitry A. Kazakov
2016-12-06 20:51                                               ` Shark8
2016-12-06 21:07                                                 ` Dmitry A. Kazakov
2016-12-06 21:44                                                   ` Shark8
2016-12-06 23:23                                                     ` Randy Brukardt
2016-12-07 22:42                                                       ` Shark8
2016-12-07  1:08                                                     ` Dennis Lee Bieber
2016-12-07  6:36                                                       ` Niklas Holsti
2016-12-07 13:10                                                         ` Dennis Lee Bieber
2016-12-07 22:55                                                           ` Brian Drummond
2016-12-08  2:44                                                         ` Shark8
2016-12-07 10:04                                                       ` G.B.
2016-12-07 10:14                                                         ` G.B.
2016-12-07 10:51                                                         ` J-P. Rosen
2016-12-08 18:33                                                           ` G.B.
2016-12-09  8:26                                                             ` J-P. Rosen
2016-12-09  8:56                                                               ` G.B.
2016-12-10 15:13                                                                 ` Jacob Sparre Andersen
2016-12-11 19:50                                                                   ` Shark8
2016-12-05 22:07                                           ` Dmitry A. Kazakov
2016-12-06 23:09                                             ` Randy Brukardt
2016-12-07 10:03                                               ` Dmitry A. Kazakov
2016-12-07 22:37                                                 ` Randy Brukardt
2016-12-08  8:46                                                   ` Dmitry A. Kazakov
2016-12-10 15:24                                               ` Jacob Sparre Andersen
2016-12-09  9:12                                           ` Robert Eachus
2016-12-05 19:22                                         ` G.B.
2016-12-05 22:18                                           ` Dmitry A. Kazakov
2016-12-05 22:12                                         ` Randy Brukardt
2016-12-05 22:26                                           ` Dmitry A. Kazakov
2016-12-06  9:29                                             ` Simon Wright
2016-12-06 10:01                                               ` Dmitry A. Kazakov
2016-12-06 23:15                                             ` Randy Brukardt
2016-12-07 10:20                                               ` Dmitry A. Kazakov
2016-12-07 22:26                                                 ` Randy Brukardt
2016-12-08  8:57                                                   ` Dmitry A. Kazakov
2016-12-08  9:42                                                     ` G.B.
2016-12-08 10:03                                                       ` Dmitry A. Kazakov
2016-12-08 18:35                                                         ` G.B.
2016-12-09  9:38                                                           ` Dmitry A. Kazakov
2016-12-11 11:21                                                             ` G.B.
2016-12-11 12:28                                                               ` Dmitry A. Kazakov
2016-12-11 13:31                                                                 ` G.B.
2016-12-11 15:40                                                                   ` Dmitry A. Kazakov
2016-12-11 20:51                                                                     ` G.B.
2016-12-12  8:27                                                                       ` Dmitry A. Kazakov
2016-12-12 15:31                                                                         ` G.B.
2016-12-12 17:39                                                                           ` Dmitry A. Kazakov
2016-12-12 18:55                                                                             ` G.B.
2016-12-12 20:53                                                                               ` Dmitry A. Kazakov
2016-12-13  7:15                                                                                 ` G.B.
2016-12-13  8:27                                                                                   ` Dmitry A. Kazakov
2016-12-13 10:39                                                                                     ` G.B.
2016-12-13 11:19                                                                                       ` Dmitry A. Kazakov
2016-12-13 16:59                                                                                         ` G.B.
2016-12-13 21:11                                                                                           ` Dmitry A. Kazakov
2016-12-13 22:13                                                                                             ` Shark8
2016-12-14  8:42                                                                                               ` Dmitry A. Kazakov
2016-12-14 11:04                                                                                                 ` G.B.
2016-12-14 11:25                                                                                                   ` Dmitry A. Kazakov
2016-12-14 12:44                                                                                                     ` G.B.
2016-12-14 12:52                                                                                                       ` Dmitry A. Kazakov
2016-12-14 16:31                                                                                                         ` G.B.
2016-12-14 16:52                                                                                                           ` Dmitry A. Kazakov
2016-12-14 18:14                                                                                                             ` G.B.
2016-12-14 12:05                                                                                                 ` G.B.
2016-12-14 19:23                                                                                                 ` Shark8
2016-12-14 20:04                                                                                                   ` Dmitry A. Kazakov
2016-12-14 21:46                                                                                                     ` Shark8
2016-12-15  8:41                                                                                                       ` Dmitry A. Kazakov
2016-12-15 10:31                                                                                                         ` G.B.
2016-12-15 13:17                                                                                                           ` Dmitry A. Kazakov
2016-12-15 13:27                                                                                                             ` Dmitry A. Kazakov
2016-12-15 19:50                                                                                                             ` G.B.
2016-12-16 10:04                                                                                                               ` Dmitry A. Kazakov
2016-12-16 11:48                                                                                                                 ` G.B.
2016-12-16 12:56                                                                                                                   ` Stefan.Lucks
2016-12-16 19:59                                                                                                                     ` Randy Brukardt
2016-12-16 20:35                                                                                                                     ` G.B.
2016-12-17  9:33                                                                                                                       ` Stefan.Lucks
2016-12-19 22:57                                                                                                                         ` Randy Brukardt
2016-12-16 13:24                                                                                                                   ` Dmitry A. Kazakov
2016-12-15 14:34                                                                                                         ` Shark8
2016-12-15 14:53                                                                                                           ` Dmitry A. Kazakov
2016-12-15 22:34                                                                                                             ` Shark8
2016-12-16  8:28                                                                                                               ` Dmitry A. Kazakov
2016-12-17  3:46                                                                                                                 ` Shark8
2016-12-14 12:21                                                                                             ` G.B.
2016-12-14 12:55                                                                                               ` Dmitry A. Kazakov
2016-12-14 16:21                                                                                                 ` G.B.
2016-12-14 16:55                                                                                                   ` Dmitry A. Kazakov
2016-12-14 18:55                                                                                                     ` G.B.
2016-12-13 18:25                                                                                         ` Shark8
2016-12-13 21:11                                                                                           ` Dmitry A. Kazakov
2016-12-13 22:32                                                                                             ` Shark8
2016-12-14  8:54                                                                                               ` Dmitry A. Kazakov
2016-12-14 22:53                                                                                                 ` Randy Brukardt
2016-12-15  8:44                                                                                                   ` Dmitry A. Kazakov
2016-12-15 22:19                                                                                                     ` Randy Brukardt
2016-12-16  8:38                                                                                                       ` Dmitry A. Kazakov
2016-12-16 19:51                                                                                                         ` Randy Brukardt
2016-12-17  9:13                                                                                                           ` Dmitry A. Kazakov
2016-12-19 22:33                                                                                                             ` Randy Brukardt
2016-12-20 11:00                                                                                                               ` Dmitry A. Kazakov
2016-12-21  0:54                                                                                                                 ` Shark8
2016-12-21  0:59                                                                                                                 ` Randy Brukardt
2016-12-21 15:56                                                                                                                   ` Dmitry A. Kazakov
2016-12-21 18:26                                                                                                                     ` G.B.
2016-12-21 21:15                                                                                                                       ` Dmitry A. Kazakov
2016-12-22  9:54                                                                                                                         ` G.B.
2016-12-22 10:16                                                                                                                           ` Dmitry A. Kazakov
2016-12-14 11:46                                                                                             ` G.B.
2016-12-12 19:48                                                                             ` Shark8
2016-12-12 20:46                                                                               ` Dmitry A. Kazakov
2016-12-12 21:33                                                                                 ` Shark8
2016-12-13  8:28                                                                                   ` Dmitry A. Kazakov
2016-12-13 18:53                                                                                     ` Shark8
2016-12-13 21:11                                                                                       ` Dmitry A. Kazakov
2016-12-13 22:16                                                                                         ` Shark8
2016-12-14  9:00                                                                                           ` Dmitry A. Kazakov
2016-12-11 23:58                                                                   ` Paul Rubin
2016-12-12  8:33                                                                     ` Dmitry A. Kazakov
2016-12-12 15:23                                                                       ` G.B.
2016-12-12 15:51                                                                         ` G.B.
2016-12-09 21:46                                                     ` Randy Brukardt
2016-12-13 11:56                                         ` Alejandro R. Mosteo
2016-12-13 15:02                                           ` Dmitry A. Kazakov
2016-12-13 17:38                                             ` Alejandro R. Mosteo
2016-12-05 22:06                                       ` Randy Brukardt [this message]
2016-11-29 17:53 ` Niklas Holsti
2016-11-29 18:21   ` Dmitry A. Kazakov
2016-11-29 20:45   ` Shark8
2016-11-30  0:03     ` Randy Brukardt
2016-11-30  0:59       ` Shark8
2016-12-01 10:33   ` AdaMagica
2016-11-29 23:52 ` Randy Brukardt
2016-11-30  1:24   ` Shark8
2016-11-30 22:12     ` Randy Brukardt
2016-11-30  1:29   ` Shark8
2016-11-30 22:17     ` Randy Brukardt
2016-12-01  1:21       ` Shark8
2016-12-01 22:07         ` Randy Brukardt
2016-12-01 10:06   ` AdaMagica
  -- strict thread matches above, loose matches on Subject: below --
2016-12-09 21:41 Randy Brukardt
2016-12-09 22:32 ` Niklas Holsti
2016-12-13  0:41   ` Randy Brukardt
2016-12-13  2:34     ` Shark8
2016-12-13 22:35       ` Randy Brukardt
2016-12-14  0:38         ` Shark8
2016-12-13 20:45     ` Niklas Holsti
2016-12-13 23:19       ` Randy Brukardt
2016-12-14  0:53         ` Shark8
2016-12-14 22:22           ` Randy Brukardt
2016-12-13 22:45 Randy Brukardt
2016-12-14 22:40 Randy Brukardt
2016-12-15  8:48 ` Dmitry A. Kazakov
2016-12-15 22:24   ` Randy Brukardt
2016-12-16  8:40     ` Dmitry A. Kazakov
2016-12-16 19:46       ` Randy Brukardt
2016-12-16 20:14         ` Dmitry A. Kazakov
2016-12-19 22:52           ` Randy Brukardt
2016-12-20 10:59             ` Dmitry A. Kazakov
2016-12-21  0:50               ` Randy Brukardt
2016-12-21 15:56                 ` Dmitry A. Kazakov
2016-12-21 22:03 Randy Brukardt
2016-12-21 23:02 ` Shark8
2016-12-21 22:12 Randy Brukardt
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