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Re: Eval of expr with 'or' and 'and' within

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On 06/14/2013 10:49 AM, Steven D'Aprano wrote:
> Correct. In Python, all boolean expressions are duck-typed: they aren't 
> restricted to True and False, but to any "true-ish" and "false-ish" 
> value, or as the Javascript people call them, truthy and falsey values.
> <snip>
> There are a couple of anomalies -- the timestamp representing midnight is 
> falsey, because it is implemented as a zero number of seconds; also 
> exhausted iterators and generators ought to be considered falsey, since 
> they are empty, but because they don't know they are empty until called, 
> they are actually treated as truthy. But otherwise, the model is very 
> clean.

Good explanation! Definitely enlightened me.  Thank you.

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Eval of expr with 'or' and 'and' within Nick the Gr33k <support@superhost.gr> - 2013-06-14 12:50 +0300
  Re: Eval of expr with 'or' and 'and' within Fábio Santos <fabiosantosart@gmail.com> - 2013-06-14 11:03 +0100
  Re: Eval of expr with 'or' and 'and' within Robert Kern <robert.kern@gmail.com> - 2013-06-14 11:14 +0100
    Re: Eval of expr with 'or' and 'and' within Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-14 16:09 +0000
      Re: Eval of expr with 'or' and 'and' within rusi <rustompmody@gmail.com> - 2013-06-14 09:21 -0700
      Re: Eval of expr with 'or' and 'and' within Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-14 20:03 +0200
        Re: Eval of expr with 'or' and 'and' within rusi <rustompmody@gmail.com> - 2013-06-14 11:37 -0700
          Re: Eval of expr with 'or' and 'and' within Joshua Landau <joshua.landau.ws@gmail.com> - 2013-06-14 19:47 +0100
      Re: Eval of expr with 'or' and 'and' within alex23 <wuwei23@gmail.com> - 2013-06-14 23:50 -0700
        Re: Eval of expr with 'or' and 'and' within Nick the Gr33k <support@superhost.gr> - 2013-06-15 10:04 +0300
          Re: Eval of expr with 'or' and 'and' within Denis McMahon <denismfmcmahon@gmail.com> - 2013-06-15 07:49 +0000
            Re: Eval of expr with 'or' and 'and' within Nick the Gr33k <support@superhost.gr> - 2013-06-15 10:59 +0300
  Re: Eval of expr with 'or' and 'and' within Grant Edwards <invalid@invalid.invalid> - 2013-06-14 14:49 +0000
    Re: Eval of expr with 'or' and 'and' within Nick the Gr33k <support@superhost.gr> - 2013-06-14 18:16 +0300
      Re: Eval of expr with 'or' and 'and' within Nobody <nobody@nowhere.com> - 2013-06-14 17:42 +0100
        Re: Eval of expr with 'or' and 'and' within Grant Edwards <invalid@invalid.invalid> - 2013-06-14 19:30 +0000
          Re: Eval of expr with 'or' and 'and' within Nobody <nobody@nowhere.com> - 2013-06-15 00:02 +0100
        Re: Eval of expr with 'or' and 'and' within Nick the Gr33k <support@superhost.gr> - 2013-06-15 10:57 +0300
  Re: Eval of expr with 'or' and 'and' within Michael Torrie <torriem@gmail.com> - 2013-06-14 10:29 -0600
    Re: Eval of expr with 'or' and 'and' within Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-14 16:49 +0000
      Re: Eval of expr with 'or' and 'and' within Michael Torrie <torriem@gmail.com> - 2013-06-14 11:28 -0600
      Re: Eval of expr with 'or' and 'and' within MRAB <python@mrabarnett.plus.com> - 2013-06-14 18:49 +0100
      Re: Eval of expr with 'or' and 'and' within Chris Angelico <rosuav@gmail.com> - 2013-06-15 03:56 +1000
        Re: Eval of expr with 'or' and 'and' within Grant Edwards <invalid@invalid.invalid> - 2013-06-14 19:33 +0000
          Re: Eval of expr with 'or' and 'and' within Chris Angelico <rosuav@gmail.com> - 2013-06-15 09:56 +1000
        Re: Eval of expr with 'or' and 'and' within Nobody <nobody@nowhere.com> - 2013-06-15 00:09 +0100
          Re: Eval of expr with 'or' and 'and' within Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-15 01:34 +0000
            Re: Eval of expr with 'or' and 'and' within Cameron Simpson <cs@zip.com.au> - 2013-06-15 12:03 +1000
              NANs [was Re: Eval of expr with 'or' and 'and' within] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-15 04:22 +0000
            Re: Eval of expr with 'or' and 'and' within Chris Angelico <rosuav@gmail.com> - 2013-06-15 12:21 +1000
      Re: Eval of expr with 'or' and 'and' within Nobody <nobody@nowhere.com> - 2013-06-15 00:06 +0100
        Re: Eval of expr with 'or' and 'and' within MRAB <python@mrabarnett.plus.com> - 2013-06-15 01:26 +0100
  Re: Eval of expr with 'or' and 'and' within Benjamin Kaplan <benjamin.kaplan@case.edu> - 2013-06-14 09:47 -0700
    Re: Eval of expr with 'or' and 'and' within Nick the Gr33k <support@superhost.gr> - 2013-06-14 20:01 +0300
      Re: Eval of expr with 'or' and 'and' within Robert Kern <robert.kern@gmail.com> - 2013-06-14 18:27 +0100
      Re: Eval of expr with 'or' and 'and' within Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-06-14 22:05 +0300
      Re: Eval of expr with 'or' and 'and' within Grant Edwards <invalid@invalid.invalid> - 2013-06-14 19:36 +0000
  Re: Eval of expr with 'or' and 'and' within Cameron Simpson <cs@zip.com.au> - 2013-06-15 10:14 +1000
    Re: Eval of expr with 'or' and 'and' within Nick the Gr33k <support@superhost.gr> - 2013-06-15 11:20 +0300
      Re: Eval of expr with 'or' and 'and' within Lele Gaifax <lele@metapensiero.it> - 2013-06-15 11:48 +0200
        Re: Eval of expr with 'or' and 'and' within Nick the Gr33k <support@superhost.gr> - 2013-06-15 16:24 +0300
        Re: Eval of expr with 'or' and 'and' within Nick the Gr33k <support@superhost.gr> - 2013-06-15 16:28 +0300

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