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Re: Python variable assigning problems...

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ICT Ezy writes:
> On Friday, December 11, 2015 at 8:40:18 AM UTC-8, Ian wrote:
>> 
>> No, it actually happens left to right. "x = y = z = 0" means "assign
>> 0 to x, then assign 0 to y, then assign 0 to z." It doesn't mean
>> "assign 0 to z, then assign z to y, etc." This works:
>> 
>> >>> d = d['foo'] = {}
>> >>> d
>> {'foo': {...}}
>> 
>> This doesn't:
>> 
>> >>> del d
>> >>> d['foo'] = d = {}
>> Traceback (most recent call last):
>>   File "<stdin>", line 1, in <module>
>> NameError: name 'd' is not defined
>
> Deat Ian,
> Thank you very much your answer, but
> above answer from Robin Koch and your answer is different. What's the
> actually process here? I agree with Robin Koch, but your answer is
> correct. Pl explain differences ?

Python language reference, at 7.2 Assignment statements, says this:

# An assignment statement evaluates the expression list (remember that
# this can be a single expression or a comma-separated list, the latter
# yielding a tuple) and assigns the single resulting object to each of
# the target lists, from left to right.

To simplify a bit, it's talking about a statement of this form:

     target_list = target_list = target_list = expression_list

And it says what Ian said: the value of the expression is assigned to
each target *from left to right*.

<https://docs.python.org/3/reference/simple_stmts.html#assignment-statements>

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Thread

Python variable assigning problems... ICT Ezy <ictezy@gmail.com> - 2015-12-09 09:49 -0800
  Re: Python variable assigning problems... Joel Goldstick <joel.goldstick@gmail.com> - 2015-12-09 12:51 -0500
  Re: Python variable assigning problems... Joel Goldstick <joel.goldstick@gmail.com> - 2015-12-09 12:52 -0500
  Re: Python variable assigning problems... Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-12-09 21:38 +0000
  Re: Python variable assigning problems... Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-12-10 16:33 +1100
  Re: Python variable assigning problems... Denis McMahon <denismfmcmahon@gmail.com> - 2015-12-10 14:03 +0000
    Re: Python variable assigning problems... ICT Ezy <ictezy@gmail.com> - 2015-12-11 08:10 -0800
      Re: Python variable assigning problems... Robin Koch <robin.koch@t-online.de> - 2015-12-11 17:24 +0100
        Re: Python variable assigning problems... Ian Kelly <ian.g.kelly@gmail.com> - 2015-12-11 09:39 -0700
          Re: Python variable assigning problems... Robin Koch <robin.koch@t-online.de> - 2015-12-11 18:52 +0100
            Re: Python variable assigning problems... ICT Ezy <ictezy@gmail.com> - 2015-12-11 10:23 -0800
          Re: Python variable assigning problems... ICT Ezy <ictezy@gmail.com> - 2015-12-11 10:05 -0800
            Re: Python variable assigning problems... Michael Torrie <torriem@gmail.com> - 2015-12-11 11:20 -0700
              Re: Python variable assigning problems... ICT Ezy <ictezy@gmail.com> - 2015-12-11 10:25 -0800
            Re: Python variable assigning problems... Jussi Piitulainen <harvesting@is.invalid> - 2015-12-11 20:27 +0200
              Re: Python variable assigning problems... ICT Ezy <ictezy@gmail.com> - 2015-12-11 10:54 -0800
              Re: Python variable assigning problems... ICT Ezy <ictezy@gmail.com> - 2015-12-11 10:55 -0800
        Re: Python variable assigning problems... ICT Ezy <ictezy@gmail.com> - 2015-12-11 10:00 -0800
          Re: Python variable assigning problems... Michael Torrie <torriem@gmail.com> - 2015-12-11 11:10 -0700
      Re: Python variable assigning problems... Ian Kelly <ian.g.kelly@gmail.com> - 2015-12-11 09:36 -0700

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