Re: while loop - multiple condition

From	Rob Gaddi <rgaddi@technologyhighland.invalid>
Newsgroups	comp.lang.python
Subject	Re: while loop - multiple condition
Date	2014-10-13 09:12 -0700
Organization	Highland Technology, Inc.
Message-ID	<20141013091248.1ffd94a0@rg.highlandtechnology.com> (permalink)
References	(4 earlier) <loom.20141012T195709-937@post.gmane.org> <mailman.14798.1413137019.18130.python-list@python.org> <878uklcd3r.fsf@elektro.pacujo.net> <mailman.14805.1413146405.18130.python-list@python.org> <543b0706$0$13005$c3e8da3$5496439d@news.astraweb.com>

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On Mon, 13 Oct 2014 09:56:02 +1100
Steven D'Aprano <steve+comp.lang.python@pearwood.info> wrote:
> 
> When you have multiple clauses in the condition, it's easier to reason about
> them if you write the clauses as positive statements rather than negative
> statements, that is, "something is true" rather than "something is not
> true", and then use `not` to reverse it if you want to loop *until* the
> overall condition is true.
> 

I was just explaining this concept to a young pup the other day.  De
Morgan's lets you say that (not (p and q)) == ((not p) or (not q)), but
the positive logic flavor is substantially less error-prone.  People
are fundamentally not as good at thinking about inverted logic.

-- 
Rob Gaddi, Highland Technology -- www.highlandtechnology.com
Email address domain is currently out of order.  See above to fix.

Thread

Re: while loop - multiple condition Chris Angelico <rosuav@gmail.com> - 2014-10-13 05:03 +1100
  Re: while loop - multiple condition Marko Rauhamaa <marko@pacujo.net> - 2014-10-12 22:16 +0300
    Re: while loop - multiple condition Chris Angelico <rosuav@gmail.com> - 2014-10-13 06:22 +1100
    Re: while loop - multiple condition Tim Chase <python.list@tim.thechases.com> - 2014-10-12 15:42 -0500
      Re: while loop - multiple condition Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-10-13 09:56 +1100
        Re: while loop - multiple condition Rob Gaddi <rgaddi@technologyhighland.invalid> - 2014-10-13 09:12 -0700
          Re: while loop - multiple condition Rustom Mody <rustompmody@gmail.com> - 2014-10-13 09:26 -0700
            Re: while loop - multiple condition Rob Gaddi <rgaddi@technologyhighland.invalid> - 2014-10-13 09:43 -0700
              Re: while loop - multiple condition Rustom Mody <rustompmody@gmail.com> - 2014-10-13 10:12 -0700
                Re: while loop - multiple condition Michael Torrie <torriem@gmail.com> - 2014-10-13 16:08 -0600
                Re: while loop - multiple condition wxjmfauth@gmail.com - 2014-10-13 23:34 -0700
      Re: while loop - multiple condition giacomo boffi <pecore@pascolo.net> - 2014-10-15 01:04 +0200
        Re: while loop - multiple condition Chris Angelico <rosuav@gmail.com> - 2014-10-15 10:16 +1100

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