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Groups > comp.lang.python > #96679

Re: True == 1 weirdness

From Dennis Lee Bieber <wlfraed@ix.netcom.com>
Subject Re: True == 1 weirdness
Date 2015-09-16 09:28 -0400
Organization IISS Elusive Unicorn
References <0b949fe0-09b4-46b0-b4ac-a85a9bfebfd5@googlegroups.com>
Newsgroups comp.lang.python
Message-ID <mailman.635.1442410144.8327.python-list@python.org> (permalink)

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On Wed, 16 Sep 2015 05:16:21 -0700 (PDT), "Blake T. Garretson"
<blake.garretson@gmail.com> declaimed the following:

>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
>>>>
>
>You can see that in the first test we get True as expected.  The second test yield False, because True does not equal 1, apparently.  Fair enough.  But then the third test yields True.  Weird.  Okay, so maybe it was evaluating the right side first?  So I put the parens over to the right and it fails, so that wasn't it.  So why do the second and third test differ?

	Most likely, you've run into chained conditionals...

	a < x < b

is interpreted as

	a < x AND x < b

so...

	1 in {1:1} == 1

becomes

	1 in {1:1} AND {1:1} == 1

	True AND False
	False

	I'll admit, I didn't think the "in" operation took part in chaining.
-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
    wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/

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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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