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Simple question

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  Simple question explodeandroid@gmail.com - 2014-08-23 06:10 -0700
    Re: Simple question Chris Angelico <rosuav@gmail.com> - 2014-08-23 23:19 +1000
    Re: Simple question Peter Otten <__peter__@web.de> - 2014-08-23 15:26 +0200
    Re: Simple question "ElChino" <elchino@cnn.cn> - 2014-08-23 15:31 +0200
    Re: Simple question John Ladasky <john_ladasky@sbcglobal.net> - 2014-08-23 22:55 -0700
      Re: Simple question Chris Angelico <rosuav@gmail.com> - 2014-08-24 16:22 +1000

#76865 — Simple question

Can some one explain why this happens:
True, False = False, True
print True, False
False True

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#76866

On Sat, Aug 23, 2014 at 11:10 PM,  <explodeandroid@gmail.com> wrote:
> Can some one explain why this happens:
> True, False = False, True
> print True, False
> False True

Well, the first line changes the meanings of the names "True" and
"False", but doesn't change the things they point to. Those things
describe themselves the same way. Here's another thing you can do that
will look the same:

a, b = False, True
print a, b
False True

Fortunately, newer versions of Python don't let you reassign True and False.

ChrisA

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#76867

explodeandroid@gmail.com wrote:

> Can some one explain why this happens:
> True, False = False, True
> print True, False
> False True

You are using Python 2 where True/False are names that can be rebound. This 
is for backwards compatibility as Python didn't always have booleans and 
people made their own with

True = 1
False = 0

or similar.

In Python 3 True and False are keywords:

>>> True = False
  File "<stdin>", line 1
SyntaxError: can't assign to keyword

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#76868

<explodeandroid@gmail.com> wrote:

> Can some one explain why this happens:
> True, False = False, True
> print True, False
> False True

I assume the value of True and False can be falsified. Like the 'None'
object can be. So swapping their values and printing them is similar to:
  a = 0
  b = 1
  a, b = b, a
  print a, b

Except that True/False are initialised built-ins.

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#76922

On Saturday, August 23, 2014 6:10:29 AM UTC-7, explode...@gmail.com wrote:
> Can some one explain why this happens:
> 
> True, False = False, True
> 
> print True, False
> 
> False True

Shush!  That's one of Python's most closely-guarded secrets!  Every politician on Earth will want to learn to program in Python after seeing that!

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#76924

On Sun, Aug 24, 2014 at 3:55 PM, John Ladasky
<john_ladasky@sbcglobal.net> wrote:
> Shush!  That's one of Python's most closely-guarded secrets!  Every politician on Earth will want to learn to program in Python after seeing that!
>

Not really, the legal profession has known about this for centuries.

(Princess Zara, presenting Sir Bailey Barre, Q.C., M.P.)
     A complicated gentleman allow to present,
     Of all the arts and faculties the terse embodiment,
     He's a great arithmetician who can demonstrate with ease
     That two and two are three or five or anything you please;
     An eminent Logician who can make it clear to you
     That black is white--when looked at from the proper point of view;
     A marvelous Philologist who'll undertake to show
     That "yes" is but another and a neater form of "no.

>From Gilbert & Sullivan's "Utopia, Ltd", dating back to 1893. Python 2
continues this excellent tradition of permitting truth to be redefined
at will, but Python 3 adopts the view of the narrow-minded pedant who
still believes that two and two makes four. It's an opinionated
language, and that helps you to avoid weirdnesses :)

ChrisA

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