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Re: Short-circuit Logic

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On 05/30/2013 08:56 AM, Chris Angelico wrote:
> On Fri, May 31, 2013 at 1:02 AM, Ethan Furman <ethan@stoneleaf.us> wrote:
>> On 05/30/2013 05:58 AM, Chris Angelico wrote:
>>> If you iterate from 1000 to 173, you get nowhere. This is the expected
>>> behaviour; this is what a C-style for loop would be written as, it's
>>> what range() does, it's the normal thing. Going from a particular
>>> starting point to a particular ending point that's earlier than the
>>> start results in no iterations. The alternative would be an infinite
>>> number of iterations, which is far far worse.
>>
>> If the bug is the extra three zeros (maybe it should have been two), then
>> silently skipping the loop is the "far, far worse" scenario.  With the
>> infinite loop you at least know something went wrong, and you know it pretty
>> darn quick (since you are testing, right? ;).
>
> You're assuming you can casually hit Ctrl-C to stop an infinite loop,
> meaning that it's trivial. It's not. Not everything lets you do that;
> or possibly halting the process will halt far more than you intended.
> What if you're editing live code in something that's had uninterrupted
> uptime for over a year? Doing nothing is much safer than getting stuck
> in an infinite loop. And yes, I have done exactly that, though not in
> Python. Don't forget, your start/stop figures mightn't be constants,
> so you might not see it in testing. I can't imagine ANY scenario where
> you'd actually *want* the infinite loop behaviour, while there are
> plenty where you want it to skip the loop, and would otherwise have to
> guard it with an if.

We're not talking about skipping the loop on purpose, but on accident. 
Sure, taking a system down is no fun -- on the other hand, how much data 
corruption can occur before somebody realises there's a problem, and 
then how long to track it down to a silently, accidently, skipped loop?

--
~Ethan~

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Short-circuit Logic Ahmed Abdulshafy <abdulshafy@gmail.com> - 2013-05-26 04:11 -0700
  Re: Short-circuit Logic Roy Smith <roy@panix.com> - 2013-05-26 07:38 -0400
  Re: Short-circuit Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-26 12:13 +0000
    Re: Short-circuit Logic Ahmed Abdulshafy <abdulshafy@gmail.com> - 2013-05-27 13:11 -0700
      Re: Short-circuit Logic Nobody <nobody@nowhere.com> - 2013-05-28 01:10 +0100
        Re: Short-circuit Logic Ahmed Abdulshafy <abdulshafy@gmail.com> - 2013-05-28 01:39 -0700
          RE: Short-circuit Logic Carlos Nepomuceno <carlosnepomuceno@outlook.com> - 2013-05-28 12:32 +0300
          Re: Short-circuit Logic Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-05-28 12:45 +0100
          Re: Short-circuit Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-28 13:51 +0000
            Re: Short-circuit Logic Grant Edwards <invalid@invalid.invalid> - 2013-05-28 15:14 +0000
              Re: Short-circuit Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-28 15:55 +0000
      Re: Short-circuit Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-28 13:48 +0000
        Re: Short-circuit Logic Chris Angelico <rosuav@gmail.com> - 2013-05-29 00:01 +1000
        Re: Short-circuit Logic Ahmed Abdulshafy <abdulshafy@gmail.com> - 2013-05-29 07:27 -0700
          Re: Short-circuit Logic Chris Angelico <rosuav@gmail.com> - 2013-05-30 00:32 +1000
          Re: Short-circuit Logic rusi <rustompmody@gmail.com> - 2013-05-29 07:33 -0700
            Re: Short-circuit Logic Ian Kelly <ian.g.kelly@gmail.com> - 2013-05-29 10:50 -0600
              Re: Short-circuit Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-30 02:28 +0000
                Re: Short-circuit Logic Chris Angelico <rosuav@gmail.com> - 2013-05-30 13:45 +1000
                Re: Short-circuit Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-30 05:42 +0000
                Re: Short-circuit Logic Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-05-30 10:22 +0300
                Re: Short-circuit Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-30 08:29 +0000
                Re: Short-circuit Logic Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-05-30 12:07 +0300
                Re: Short-circuit Logic Nobody <nobody@nowhere.com> - 2013-05-30 23:55 +0100
                Re: Short-circuit Logic Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-05-30 19:31 -0400
                Re: Short-circuit Logic Stefan Drees <stefan@drees.name> - 2013-05-31 17:34 +0200
                Re: Short-circuit Logic Roy Smith <roy@panix.com> - 2013-05-30 08:48 -0400
                Re: Short-circuit Logic Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-05-30 19:38 -0400
                Re: Short-circuit Logic Nobody <nobody@nowhere.com> - 2013-05-31 02:10 +0100
                Re: Short-circuit Logic Roy Smith <roy@panix.com> - 2013-05-30 21:21 -0400
                Re: Short-circuit Logic Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-05-30 21:57 -0400
                Re: Short-circuit Logic Michael Torrie <torriem@gmail.com> - 2013-05-30 21:33 -0600
                RE: Short-circuit Logic Carlos Nepomuceno <carlosnepomuceno@outlook.com> - 2013-05-31 03:03 +0300
                Re: Short-circuit Logic Chris Angelico <rosuav@gmail.com> - 2013-05-30 18:29 +1000
                RE: Short-circuit Logic Carlos Nepomuceno <carlosnepomuceno@outlook.com> - 2013-05-31 00:03 +0300
                Re: Short-circuit Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-31 05:13 +0000
                RE: Short-circuit Logic Carlos Nepomuceno <carlosnepomuceno@outlook.com> - 2013-05-31 09:42 +0300
                Re: Short-circuit Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-31 08:11 +0000
                Re: Short-circuit Logic Chris Angelico <rosuav@gmail.com> - 2013-05-31 17:09 +1000
                Re: Short-circuit Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-31 08:45 +0000
                Re: Short-circuit Logic Roy Smith <roy@panix.com> - 2013-05-31 09:20 -0400
                RE: Short-circuit Logic Carlos Nepomuceno <carlosnepomuceno@outlook.com> - 2013-06-01 10:23 +0300
                Re: Short-circuit Logic 88888 Dihedral <dihedral88888@gmail.com> - 2013-05-30 20:11 -0700
            Re: Short-circuit Logic Dave Angel <davea@davea.name> - 2013-05-29 20:23 -0400
              Re: Short-circuit Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-30 05:20 +0000
          Re: Short-circuit Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-30 05:10 +0000
            Re: Short-circuit Logic Chris Angelico <rosuav@gmail.com> - 2013-05-30 15:22 +1000
              Re: Short-circuit Logic Roy Smith <roy@panix.com> - 2013-05-30 08:40 -0400
                Re: Short-circuit Logic Chris Angelico <rosuav@gmail.com> - 2013-05-30 22:58 +1000
                Re: Short-circuit Logic rusi <rustompmody@gmail.com> - 2013-05-30 09:58 -0700
                Re: Short-circuit Logic Chris Angelico <rosuav@gmail.com> - 2013-05-31 03:23 +1000
                Re: Short-circuit Logic Rick Johnson <rantingrickjohnson@gmail.com> - 2013-05-30 17:13 -0700
                Re: Short-circuit Logic Chris Angelico <rosuav@gmail.com> - 2013-05-31 12:29 +1000
                Re: Short-circuit Logic Ethan Furman <ethan@stoneleaf.us> - 2013-05-30 08:02 -0700
                Re: Short-circuit Logic Chris Angelico <rosuav@gmail.com> - 2013-05-31 01:56 +1000
                Re: Short-circuit Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-30 16:40 +0000
                Re: Short-circuit Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-30 19:22 +0000
                Re: Short-circuit Logic Chris Angelico <rosuav@gmail.com> - 2013-05-31 07:46 +1000
                Re: Short-circuit Logic Ethan Furman <ethan@stoneleaf.us> - 2013-05-30 09:30 -0700
              Re: Short-circuit Logic Neil Cerutti <neilc@norwich.edu> - 2013-05-30 19:30 +0000
                Re: Short-circuit Logic Ian Kelly <ian.g.kelly@gmail.com> - 2013-05-30 13:49 -0600
  Re: Short-circuit Logic Terry Jan Reedy <tjreedy@udel.edu> - 2013-05-26 16:19 -0400
    Re: Short-circuit Logic Roy Smith <roy@panix.com> - 2013-05-26 16:22 -0400
      Re: Short-circuit Logic Terry Jan Reedy <tjreedy@udel.edu> - 2013-05-26 17:28 -0400
      Re: Short-circuit Logic Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-27 00:40 +0000
        Re: Short-circuit Logic Cameron Simpson <cs@zip.com.au> - 2013-05-27 11:57 +1000
        Re: Short-circuit Logic rusi <rustompmody@gmail.com> - 2013-05-26 21:44 -0700
        Re: Short-circuit Logic Vito De Tullio <vito.detullio@gmail.com> - 2013-05-27 06:59 +0200
  Re: Short-circuit Logic Nobody <nobody@nowhere.com> - 2013-05-27 18:52 +0100
  Re: Short-circuit Logic Ahmed Abdulshafy <abdulshafy@gmail.com> - 2013-05-27 13:08 -0700
    Re: Short-circuit Logic Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-05-27 21:36 -0400

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