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Groups > comp.lang.python > #96673

Re: True == 1 weirdness

From Jussi Piitulainen <harvesting@makes.email.invalid>
Newsgroups comp.lang.python
Subject Re: True == 1 weirdness
Date 2015-09-16 15:53 +0300
Organization A noiseless patient Spider
Message-ID <lf5h9mubk4n.fsf@ling.helsinki.fi> (permalink)
References <0b949fe0-09b4-46b0-b4ac-a85a9bfebfd5@googlegroups.com>

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Blake T. Garretson writes:

> I am maintaining some old code where the programmer used 1 for True
> because booleans hadn't been added to Python yet.  I'm getting some
> weird behaviour, so I created some simple tests to illustrate my
> issue.
>
>   >>> 1 in {1:1}        #test1
>   True
>   >>> 1 in {1:1} == 1   #test2
>   False
>   >>> (1 in {1:1}) == 1 #test3
>   True
>   >>> 1 in ({1:1} == 1) #test4
>   Traceback (most recent call last):
>     File "<stdin>", line 1, in <module>
>   TypeError: argument of type 'bool' is not iterable
>   >>>

Ouch. I love chained comparisons more than most people, but this took a
while to decipher. I blame you! Your parentheses mis-primed me for the
wrong reading :) But now I expect to see a long thread about whether
chained comparisons are a natural thing to have in the language.

The second test, test2, is interpreted (almost) as

  >>>> (1 in {1:1}) and ({1:1} == 1)

which is obviously False.

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Thread

True == 1 weirdness "Blake T. Garretson" <blake.garretson@gmail.com> - 2015-09-16 05:16 -0700
  Re: True == 1 weirdness Jussi Piitulainen <harvesting@makes.email.invalid> - 2015-09-16 15:53 +0300
    Re: True == 1 weirdness Chris Angelico <rosuav@gmail.com> - 2015-09-16 23:05 +1000
    Re: True == 1 weirdness "Blake T. Garretson" <blake.garretson@gmail.com> - 2015-09-16 06:14 -0700
    Re: True == 1 weirdness Random832 <random832@fastmail.com> - 2015-09-16 10:03 -0400
      Re: True == 1 weirdness Steven D'Aprano <steve@pearwood.info> - 2015-09-17 03:24 +1000
        Re: True == 1 weirdness Random832 <random832@fastmail.com> - 2015-09-16 13:36 -0400
        Re: True == 1 weirdness "Sven R. Kunze" <srkunze@mail.de> - 2015-09-16 19:57 +0200
        Re: True == 1 weirdness Ian Kelly <ian.g.kelly@gmail.com> - 2015-09-16 11:57 -0600
    Re: True == 1 weirdness Chris Angelico <rosuav@gmail.com> - 2015-09-17 00:26 +1000
      Re: True == 1 weirdness Marko Rauhamaa <marko@pacujo.net> - 2015-09-16 19:16 +0300
        Re: True == 1 weirdness "Sven R. Kunze" <srkunze@mail.de> - 2015-09-16 18:37 +0200
          Re: True == 1 weirdness Marko Rauhamaa <marko@pacujo.net> - 2015-09-16 19:53 +0300
            Re: True == 1 weirdness Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-09-17 18:30 +1200
        Re: True == 1 weirdness Random832 <random832@fastmail.com> - 2015-09-16 12:57 -0400
          Re: True == 1 weirdness Steven D'Aprano <steve@pearwood.info> - 2015-09-17 03:39 +1000
            Re: True == 1 weirdness Marko Rauhamaa <marko@pacujo.net> - 2015-09-16 20:42 +0300
              Re: True == 1 weirdness Emile van Sebille <emile@fenx.com> - 2015-09-16 11:46 -0700
            Re: True == 1 weirdness Grant Edwards <invalid@invalid.invalid> - 2015-09-16 17:46 +0000
              Re: True == 1 weirdness "Sven R. Kunze" <srkunze@mail.de> - 2015-09-16 20:13 +0200
                Re: True == 1 weirdness Grant Edwards <invalid@invalid.invalid> - 2015-09-16 19:47 +0000
                Re: True == 1 weirdness Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-16 21:25 +0100
                Re: True == 1 weirdness Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-09-17 18:36 +1200
                Re: True == 1 weirdness "Sven R. Kunze" <srkunze@mail.de> - 2015-09-16 23:05 +0200
                Re: True == 1 weirdness Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-09-17 18:39 +1200
                Re: True == 1 weirdness "Sven R. Kunze" <srkunze@mail.de> - 2015-09-17 22:46 +0200
                Re: True == 1 weirdness Tim Chase <python.list@tim.thechases.com> - 2015-09-17 16:26 -0500
                Re: True == 1 weirdness "Sven R. Kunze" <srkunze@mail.de> - 2015-09-17 23:52 +0200
                Re: True == 1 weirdness Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-16 22:30 +0100
                Re: True == 1 weirdness "Sven R. Kunze" <srkunze@mail.de> - 2015-09-17 00:15 +0200
                Re: True == 1 weirdness Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-17 01:06 +0100
                Re: True == 1 weirdness Steven D'Aprano <steve@pearwood.info> - 2015-09-17 11:33 +1000
                Re: True == 1 weirdness Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-17 10:56 +0100
                Re: True == 1 weirdness alister <alister.nospam.ware@ntlworld.com> - 2015-09-17 12:07 +0000
                Re: True == 1 weirdness Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-17 13:27 +0100
                Re: True == 1 weirdness Steven D'Aprano <steve@pearwood.info> - 2015-09-17 12:34 +1000
                Re: True == 1 weirdness Chris Angelico <rosuav@gmail.com> - 2015-09-17 10:53 +1000
                Re: True == 1 weirdness Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-09-17 18:42 +1200
                Re: True == 1 weirdness Emile van Sebille <emile@fenx.com> - 2015-09-16 18:12 -0700
                Re: True == 1 weirdness Tim Chase <python.list@tim.thechases.com> - 2015-09-16 18:10 -0500
            Re: True == 1 weirdness "Sven R. Kunze" <srkunze@mail.de> - 2015-09-16 19:53 +0200
              Re: True == 1 weirdness Marko Rauhamaa <marko@pacujo.net> - 2015-09-16 22:47 +0300
            Re: True == 1 weirdness Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-16 21:29 +0100
            Re: True == 1 weirdness Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-16 22:27 +0100
        Re: True == 1 weirdness "Sven R. Kunze" <srkunze@mail.de> - 2015-09-16 19:23 +0200
          Re: True == 1 weirdness Grant Edwards <invalid@invalid.invalid> - 2015-09-16 17:27 +0000
            Re: True == 1 weirdness Emile van Sebille <emile@fenx.com> - 2015-09-16 10:41 -0700
            Re: True == 1 weirdness Steven D'Aprano <steve@pearwood.info> - 2015-09-17 03:42 +1000
              Re: True == 1 weirdness Grant Edwards <invalid@invalid.invalid> - 2015-09-16 17:44 +0000
                Re: True == 1 weirdness Random832 <random832@fastmail.com> - 2015-09-16 13:55 -0400
                Re: True == 1 weirdness Ian Kelly <ian.g.kelly@gmail.com> - 2015-09-16 11:55 -0600
                Re: True == 1 weirdness Steven D'Aprano <steve@pearwood.info> - 2015-09-17 11:16 +1000
            Re: True == 1 weirdness Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-16 21:22 +0100
        Re: True == 1 weirdness Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-16 21:17 +0100
      Re: True == 1 weirdness Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-09-17 18:24 +1200
        Re: True == 1 weirdness Jussi Piitulainen <harvesting@makes.email.invalid> - 2015-09-17 10:06 +0300
          Re: True == 1 weirdness Ian Kelly <ian.g.kelly@gmail.com> - 2015-09-17 12:49 -0600
            Re: True == 1 weirdness Jussi Piitulainen <harvesting@makes.email.invalid> - 2015-09-17 23:24 +0300
              Re: True == 1 weirdness Random832 <random832@fastmail.com> - 2015-09-17 17:26 -0400
                Re: True == 1 weirdness Marko Rauhamaa <marko@pacujo.net> - 2015-09-18 00:38 +0300
                Re: True == 1 weirdness "Sven R. Kunze" <srkunze@mail.de> - 2015-09-17 23:49 +0200
                Re: True == 1 weirdness Chris Angelico <rosuav@gmail.com> - 2015-09-18 12:03 +1000
                Re: True == 1 weirdness Jussi Piitulainen <harvesting@makes.email.invalid> - 2015-09-18 10:10 +0300
                Re: True == 1 weirdness Steven D'Aprano <steve@pearwood.info> - 2015-09-18 22:30 +1000
          Re: True == 1 weirdness Chris Angelico <rosuav@gmail.com> - 2015-09-18 04:57 +1000
            Re: True == 1 weirdness Jussi Piitulainen <harvesting@makes.email.invalid> - 2015-09-17 23:44 +0300
    Re: True == 1 weirdness Tim Chase <python.list@tim.thechases.com> - 2015-09-16 09:38 -0500
    Re: True == 1 weirdness Random832 <random832@fastmail.com> - 2015-09-16 11:40 -0400
      Re: True == 1 weirdness Steven D'Aprano <steve@pearwood.info> - 2015-09-17 03:33 +1000
        Re: True == 1 weirdness "Sven R. Kunze" <srkunze@mail.de> - 2015-09-16 19:41 +0200
          Re: True == 1 weirdness Steven D'Aprano <steve@pearwood.info> - 2015-09-17 11:22 +1000
        Re: True == 1 weirdness Random832 <random832@fastmail.com> - 2015-09-16 13:47 -0400
          Re: True == 1 weirdness Grant Edwards <invalid@invalid.invalid> - 2015-09-16 17:52 +0000
          Re: True == 1 weirdness Steven D'Aprano <steve@pearwood.info> - 2015-09-17 11:25 +1000
            Re: True == 1 weirdness Random832 <random832@fastmail.com> - 2015-09-17 02:10 -0400
              Re: True == 1 weirdness Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-09-17 12:29 +0000
        Re: True == 1 weirdness Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-16 21:38 +0100
        Re: True == 1 weirdness Random832 <random832@fastmail.com> - 2015-09-16 16:55 -0400
        Re: True == 1 weirdness "Sven R. Kunze" <srkunze@mail.de> - 2015-09-16 23:03 +0200
    Re: True == 1 weirdness jmp <jeanmichel@sequans.com> - 2015-09-21 14:01 +0200
  Re: True == 1 weirdness jmp <jeanmichel@sequans.com> - 2015-09-16 15:08 +0200
    Re: True == 1 weirdness "Blake T. Garretson" <blake.garretson@gmail.com> - 2015-09-16 06:17 -0700
  Re: True == 1 weirdness Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-09-16 09:28 -0400
  Re: True == 1 weirdness Chris Angelico <rosuav@gmail.com> - 2015-09-17 00:57 +1000

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