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Groups > comp.lang.python > #16696

Re: Scope of variable inside list comprehensions?

From Terry Reedy <tjreedy@udel.edu>
Subject Re: Scope of variable inside list comprehensions?
Date 2011-12-05 21:23 -0500
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On 12/5/2011 5:36 PM, Roy Smith wrote:
> Well, in my defense, I did ask a pretty narrow question, "Is id
> guaranteed to be in scope in the print statement?".

Yes for 2.x, guaranteed no for 3.x.

If you had simply asked "Is the loop variable of a list comprehension 
guaranteed to be in scope after the list comprehension?", without a 
distracting example, that is the answer you would have received.

I intend(ed) to inform, not attack, hence no 'defense' needed.

>  While I will
> admit that not knowing whether I could alter the exception, or
> whether id masked a builtin or not does complexify answering some
> questions, those are questions I didn't ask :-)

Except that it bears on the question you did ask because it means that 
the code will run in 3.x but with different results, whereas a random 
name will fail in 3.x with a NameError.

-- 
Terry Jan Reedy

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Thread

Scope of variable inside list comprehensions? Roy Smith <roy@panix.com> - 2011-12-05 09:04 -0800
  Re: Scope of variable inside list comprehensions? Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2011-12-05 20:04 +0200
  Re: Scope of variable inside list comprehensions? Peter Otten <__peter__@web.de> - 2011-12-05 19:10 +0100
  Re: Scope of variable inside list comprehensions? Jean-Michel Pichavant <jeanmichel@sequans.com> - 2011-12-05 19:57 +0100
    Re: Scope of variable inside list comprehensions? Roy Smith <roy@panix.com> - 2011-12-05 11:15 -0800
    Re: Scope of variable inside list comprehensions? Roy Smith <roy@panix.com> - 2011-12-05 11:15 -0800
      Re: Scope of variable inside list comprehensions? Terry Reedy <tjreedy@udel.edu> - 2011-12-05 15:22 -0500
        Re: Scope of variable inside list comprehensions? Roy Smith <roy@panix.com> - 2011-12-05 14:36 -0800
        Re: Scope of variable inside list comprehensions? Roy Smith <roy@panix.com> - 2011-12-05 14:36 -0800
          Re: Scope of variable inside list comprehensions? Terry Reedy <tjreedy@udel.edu> - 2011-12-05 21:23 -0500
    Re: Scope of variable inside list comprehensions? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-05 22:35 +0000
      Re: Scope of variable inside list comprehensions? Roy Smith <roy@panix.com> - 2011-12-05 14:57 -0800
        Re: Scope of variable inside list comprehensions? Chris Angelico <rosuav@gmail.com> - 2011-12-06 13:35 +1100
      Re: Scope of variable inside list comprehensions? Jean-Michel Pichavant <jeanmichel@sequans.com> - 2011-12-06 11:38 +0100
  Re: Scope of variable inside list comprehensions? Rainer Grimm <r.grimm@science-computing.de> - 2011-12-05 22:42 -0800
    Re: Scope of variable inside list comprehensions? 88888 Dihedral <dihedral88888@googlemail.com> - 2011-12-06 02:16 -0800

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