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Re: Mutable objects inside tuples - good or bad?

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From Paul Kölle <paul@subsignal.org>
Subject Re: Mutable objects inside tuples - good or bad?
Date Mon, 07 Apr 2014 17:26:37 +0200
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Am 06.04.2014 09:25, schrieb Gary Herron:
> On 04/05/2014 11:53 PM, John Ladasky wrote:
>> I find this programming pattern to be useful... but can it cause
>> problems?
> No.
>
> What kind of problems are you considering?  It won't break Python. It's
> perfectly legal code.
>
> The tuple c is still immutable, consisting of two specific objects, and
> (as always) without regard to the specifics or contents of those two
> objects.
It seems a tuple's immutability is debatable, or is this another 
instance of the small-integer-reuse-implementation-detail-artifact?

Python 2.6.6 (r266:84292, Dec 26 2010, 22:31:48)
[GCC 4.4.5] on linux2
Type "help", "copyright", "credits" or "license" for more information.
 >>> a = ([1,2],[3,4])
 >>> b = a
 >>> a is b
True
 >>> a == b
True
 >>> c = (1,2,3)
 >>> d = (1,2,3)
 >>> c is d
False
 >>> c == d
True

cheers
  Paul

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Thread

Mutable objects inside tuples - good or bad? John Ladasky <john_ladasky@sbcglobal.net> - 2014-04-05 23:53 -0700
  Re: Mutable objects inside tuples - good or bad? Gary Herron <gary.herron@islandtraining.com> - 2014-04-06 00:25 -0700
  Re: Mutable objects inside tuples - good or bad? Devin Jeanpierre <jeanpierreda@gmail.com> - 2014-04-06 00:55 -0700
    Re: Mutable objects inside tuples - good or bad? Rustom Mody <rustompmody@gmail.com> - 2014-04-06 08:07 -0700
  Re: Mutable objects inside tuples - good or bad? Chris Angelico <rosuav@gmail.com> - 2014-04-06 18:25 +1000
  Re: Mutable objects inside tuples - good or bad? Devin Jeanpierre <jeanpierreda@gmail.com> - 2014-04-06 04:01 -0700
  Re: Mutable objects inside tuples - good or bad? Paul Kölle <paul@subsignal.org> - 2014-04-07 17:26 +0200
  Re: Mutable objects inside tuples - good or bad? Chris Angelico <rosuav@gmail.com> - 2014-04-08 01:44 +1000
  Re: Mutable objects inside tuples - good or bad? Paul Kölle <paul@subsignal.org> - 2014-04-07 21:46 +0200
  Re: Mutable objects inside tuples - good or bad? Chris Angelico <rosuav@gmail.com> - 2014-04-08 08:47 +1000
  Re: Mutable objects inside tuples - good or bad? Terry Reedy <tjreedy@udel.edu> - 2014-04-07 20:16 -0400
    Re: Mutable objects inside tuples - good or bad? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-04-08 02:53 +0000

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