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Re: I love assert

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From Ian Kelly <ian.g.kelly@gmail.com>
Date 2014-11-12 15:04 -0700
Subject Re: I love assert
Newsgroups comp.lang.python
Message-ID <mailman.15746.1415829905.18130.python-list@python.org> (permalink)

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On Wed, Nov 12, 2014 at 2:56 PM, Marko Rauhamaa <marko@pacujo.net> wrote:
> Ethan Furman <ethan@stoneleaf.us>:
>
>> On 11/12/2014 01:41 PM, Marko Rauhamaa wrote:
>>>
>>> Or I might indicate the exhaustion of possibilities:
>>>
>>>       if status == OK:
>>>           ...
>>>       elif status == ERROR:
>>>           ...
>>>       else:
>>>           assert status == WARNING
>>>           ...
>>
>> And here's a nice example of what one should NOT do. Imagine that a
>> new status, CONFUSED is added, the above code is not modified to
>> handle it, and for whatever reason the program is being run optimized
>> -- the assert is not there, and CONFUSED is treated the same as
>> WARNING.
>
> How would it be better if you removed the assert then?

You don't need to remove it. Just reorganize it to make sure it
indicates actual exhaustion of possibilities. E.g. using the "assert
False" pattern from your post:

if status == OK:
    ...
elif status == ERROR:
    ...
elif status == WARNING:
    ...
else:
    assert False

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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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