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Groups > comp.lang.python > #80798

Re: I love assert

From Marko Rauhamaa <marko@pacujo.net>
Newsgroups comp.lang.python
Subject Re: I love assert
Date 2014-11-15 03:30 +0200
Organization A noiseless patient Spider
Message-ID <87a93tl07u.fsf@elektro.pacujo.net> (permalink)
References (8 earlier) <28e159ff-3d64-4793-9082-05cf1553c7c2@googlegroups.com> <87h9y4owgc.fsf@elektro.pacujo.net> <54669308$0$13002$c3e8da3$5496439d@news.astraweb.com> <87h9y1l3tt.fsf@elektro.pacujo.net> <mailman.15836.1416013493.18130.python-list@python.org>

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Chris Angelico <rosuav@gmail.com>:

> On Sat, Nov 15, 2014 at 11:12 AM, Marko Rauhamaa <marko@pacujo.net> wrote:
>> Most importantly, assertion failures are not supposed to be recovered
>> from (within the program). Assertion failures can result in the loss
>> of life and limb. They can result in database corruption. They can
>> result in monetary losses. They can result in smoke coming out of the
>> monitor.
>
> Or, in theory, AssertionError just prevented any of the above from
> happening.

I'd advice against catching AssertionError and trying to recover from it
within the program. You could catch it, log it and reraise it, but since
the failure modes could be completely unexpected (really, by
definition), I would move fault-tolerance outside the failing process
and try to restore a coherent reality from there.

Assertion errors are in the same class with CPython bugs, external
signals (say, SIGKILL), security breaches, hardware failures and the
like.

For expected failure modes, other exceptions are a suitable facility.


Marko

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Thread

I love assert Peter Cacioppi <peter.cacioppi@gmail.com> - 2014-11-11 11:40 -0800
  Re: I love assert Ben Finney <ben+python@benfinney.id.au> - 2014-11-12 07:03 +1100
    Re: I love assert Grant Edwards <invalid@invalid.invalid> - 2014-11-11 21:43 +0000
  Re: I love assert Ethan Furman <ethan@stoneleaf.us> - 2014-11-11 12:08 -0800
  Re: I love assert Rob Gaddi <rgaddi@technologyhighland.invalid> - 2014-11-11 12:20 -0800
  Re: I love assert Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-11-11 20:34 +0000
  Re: I love assert TP <wingusr@gmail.com> - 2014-11-11 12:57 -0800
  Re: I love assert Terry Reedy <tjreedy@udel.edu> - 2014-11-11 17:34 -0500
  Re: I love assert Ben Finney <ben+python@benfinney.id.au> - 2014-11-12 09:52 +1100
  Re: I love assert Tim Chase <python.list@tim.thechases.com> - 2014-11-11 17:03 -0600
  Re: I love assert Peter Cacioppi <peter.cacioppi@gmail.com> - 2014-11-11 15:02 -0800
  Re: I love assert Ethan Furman <ethan@stoneleaf.us> - 2014-11-11 15:38 -0800
  Re: I love assert Dan Stromberg <drsalists@gmail.com> - 2014-11-11 17:56 -0800
  Re: I love assert Chris Angelico <rosuav@gmail.com> - 2014-11-12 13:21 +1100
  Re: I love assert Ben Finney <ben+python@benfinney.id.au> - 2014-11-12 13:35 +1100
    Re: I love assert Grant Edwards <invalid@invalid.invalid> - 2014-11-12 14:10 +0000
  Re: I love assert Chris Angelico <rosuav@gmail.com> - 2014-11-12 13:44 +1100
    Re: I love assert wxjmfauth@gmail.com - 2014-11-11 23:14 -0800
  Re: I love assert Terry Reedy <tjreedy@udel.edu> - 2014-11-12 03:29 -0500
  Re: I love assert Anton <anton.schattenfeld@gmail.com> - 2014-11-12 12:53 -0800
    Re: I love assert Marko Rauhamaa <marko@pacujo.net> - 2014-11-12 23:41 +0200
      Re: I love assert Ethan Furman <ethan@stoneleaf.us> - 2014-11-12 13:52 -0800
        Re: I love assert Marko Rauhamaa <marko@pacujo.net> - 2014-11-12 23:56 +0200
          Re: I love assert Ian Kelly <ian.g.kelly@gmail.com> - 2014-11-12 15:04 -0700
            Re: I love assert Anton <anschatten@gmail.com> - 2014-11-12 14:13 -0800
              Re: I love assert Ian Kelly <ian.g.kelly@gmail.com> - 2014-11-12 15:41 -0700
                Re: I love assert Anton <anschatten@gmail.com> - 2014-11-12 14:48 -0800
                Re: I love assert Marko Rauhamaa <marko@pacujo.net> - 2014-11-13 01:01 +0200
                Re: I love assert Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-11-15 10:40 +1100
                Re: I love assert Marko Rauhamaa <marko@pacujo.net> - 2014-11-15 02:12 +0200
                Re: I love assert Chris Angelico <rosuav@gmail.com> - 2014-11-15 12:04 +1100
                Re: I love assert Marko Rauhamaa <marko@pacujo.net> - 2014-11-15 03:30 +0200
                Re: I love assert Chris Angelico <rosuav@gmail.com> - 2014-11-15 12:48 +1100
                Re: I love assert Tim Chase <python.list@tim.thechases.com> - 2014-11-14 20:14 -0600
                Re: I love assert Chris Angelico <rosuav@gmail.com> - 2014-11-15 13:16 +1100
                Re: I love assert albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-11-29 17:35 +0000
                Re: I love assert Ian Kelly <ian.g.kelly@gmail.com> - 2014-11-12 16:02 -0700
                Re: I love assert Anton <anschatten@gmail.com> - 2014-11-12 15:43 -0800
                Re: I love assert Chris Angelico <rosuav@gmail.com> - 2014-11-13 10:10 +1100
                Re: I love assert Marko Rauhamaa <marko@pacujo.net> - 2014-11-13 01:23 +0200
                Re: I love assert Chris Angelico <rosuav@gmail.com> - 2014-11-13 10:27 +1100
                Re: I love assert Marko Rauhamaa <marko@pacujo.net> - 2014-11-13 01:31 +0200
              Re: I love assert Ethan Furman <ethan@stoneleaf.us> - 2014-11-12 14:47 -0800
                Re: I love assert Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-11-14 22:37 +1100
                Re: I love assert Ian Kelly <ian.g.kelly@gmail.com> - 2014-11-14 09:40 -0700
          Re: I love assert Ian Kelly <ian.g.kelly@gmail.com> - 2014-11-12 15:07 -0700
            Re: I love assert Marko Rauhamaa <marko@pacujo.net> - 2014-11-13 00:47 +0200
              Re: I love assert Ethan Furman <ethan@stoneleaf.us> - 2014-11-12 14:56 -0800
              Re: I love assert Chris Angelico <rosuav@gmail.com> - 2014-11-13 09:58 +1100
              Re: I love assert Ian Kelly <ian.g.kelly@gmail.com> - 2014-11-12 16:05 -0700
                Re: I love assert Marko Rauhamaa <marko@pacujo.net> - 2014-11-13 01:12 +0200
              Re: I love assert Lie Ryan <lie.1296@gmail.com> - 2014-11-14 01:09 +1100
        Re: I love assert Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-11-14 22:33 +1100
          Re: I love assert Ethan Furman <ethan@stoneleaf.us> - 2014-11-14 10:18 -0800
            Re: I love assert Marko Rauhamaa <marko@pacujo.net> - 2014-11-14 21:12 +0200
              Re: I love assert Ethan Furman <ethan@stoneleaf.us> - 2014-11-14 12:41 -0800
                Re: I love assert Marko Rauhamaa <marko@pacujo.net> - 2014-11-14 22:50 +0200
            Re: I love assert Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-11-15 13:58 +1100
              Re: I love assert Ethan Furman <ethan@stoneleaf.us> - 2014-11-14 20:09 -0800
                Re: I love assert Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-11-17 13:09 +1100
                Re: I love assert Ethan Furman <ethan@stoneleaf.us> - 2014-11-16 19:25 -0800
      Re: I love assert Anton <anschatten@gmail.com> - 2014-11-12 14:00 -0800
        Re: I love assert Anton <anschatten@gmail.com> - 2014-11-12 14:04 -0800
          Re: I love assert Marko Rauhamaa <marko@pacujo.net> - 2014-11-13 00:34 +0200
    Re: I love assert Chris Angelico <rosuav@gmail.com> - 2014-11-13 09:43 +1100
  Re: I love assert Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-11-14 22:15 +1100
  Re: I love assert Richard Riehle <rriehle@itu.edu> - 2014-11-14 14:09 -0800
    Decorators (was: Re: I love assert) Marko Rauhamaa <marko@pacujo.net> - 2014-11-15 00:18 +0200
      Re: Decorators Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-11-14 22:37 +0000
        Re: Decorators Marko Rauhamaa <marko@pacujo.net> - 2014-11-15 00:47 +0200
      Re: Decorators (was: Re: I love assert) Richard Riehle <rriehle@itu.edu> - 2014-11-14 18:19 -0800
        Re: Decorators (was: Re: I love assert) Mayank Tripathi <oquanox@gmail.com> - 2014-11-15 02:36 +0000
        Re: Decorators (was: Re: I love assert) Tim Chase <python.list@tim.thechases.com> - 2014-11-14 20:30 -0600
          Re: Decorators Marko Rauhamaa <marko@pacujo.net> - 2014-11-15 09:00 +0200
            Re: Decorators Grant Edwards <invalid@invalid.invalid> - 2014-11-15 15:32 +0000
        Re: Decorators (was: Re: I love assert) Richard Riehle <rriehle@itu.edu> - 2014-11-14 23:42 -0800
        Re: Decorators Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-11-15 13:12 +0000
          Re: Decorators Marko Rauhamaa <marko@pacujo.net> - 2014-11-15 15:24 +0200
            Re: Decorators Terry Reedy <tjreedy@udel.edu> - 2014-11-15 15:28 -0500
        Re: Decorators (was: Re: I love assert) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-11-16 02:39 +1100
  Re: I love assert TP <wingusr@gmail.com> - 2014-11-27 01:22 -0800
    Re: I love assert alister <alister.nospam.ware@ntlworld.com> - 2014-11-27 09:59 +0000
      Re: I love assert Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-11-29 12:30 +1100
        Re: I love assert MRAB <python@mrabarnett.plus.com> - 2014-11-29 02:56 +0000
          Re: I love assert Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-11-29 20:31 +1100
            Re: I love assert Chris Angelico <rosuav@gmail.com> - 2014-11-29 21:40 +1100
            Re: I love assert MRAB <python@mrabarnett.plus.com> - 2014-11-29 19:49 +0000
        Re: I love assert Chris Angelico <rosuav@gmail.com> - 2014-11-29 14:02 +1100
        Re: I love assert Ethan Furman <ethan@stoneleaf.us> - 2014-11-29 14:33 -0800
          Re: I love assert Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-11-30 19:18 +1100
            Re: I love assert Ethan Furman <ethan@stoneleaf.us> - 2014-11-30 11:34 -0800

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