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Re: Immutability and Python

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Date Tue, 30 Oct 2012 03:08:31 +1100
Subject Re: Immutability and Python
From Chris Angelico <rosuav@gmail.com>
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On Tue, Oct 30, 2012 at 2:55 AM, Paul Rubin <no.email@nospam.invalid> wrote:
> andrea crotti <andrea.crotti.0@gmail.com> writes:
>> and we want to change its state incrementing the number ...
>>  the immutability purists would instead suggest to do this:
>>     def increment(self):
>>         return NumWrapper(self.number + 1)
>
> Immutability purists would say that numbers don't have "state" and if
> you're trying to change a number's state by incrementing it, that's not
> immutability.  You end up with a rather different programming style than
> imperative programming, for example using tail recursion (maybe wrapped
> in an itertools-like higher-order function) instead of indexed loops to
> iterate over a structure.

In that case, rename increment to next_integer and TYAOOYDAO. [1]
You're not changing the state of this number, you're locating the
number which has a particular relationship to this one (in the same
way that GUI systems generally let you locate the next and previous
siblings of any given object).

ChrisA
[1] "there you are, out of your difficulty at once" - cf WS Gilbert's "Iolanthe"

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Thread

Immutability and Python andrea crotti <andrea.crotti.0@gmail.com> - 2012-10-29 15:20 +0000
  Re: Immutability and Python Paul Rubin <no.email@nospam.invalid> - 2012-10-29 08:55 -0700
    Re: Immutability and Python Chris Angelico <rosuav@gmail.com> - 2012-10-30 03:08 +1100
    Re: Immutability and Python andrea crotti <andrea.crotti.0@gmail.com> - 2012-10-29 16:33 +0000
  Re: Immutability and Python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-10-29 23:02 +0000
  Re: Immutability and Python rusi <rustompmody@gmail.com> - 2012-10-30 09:22 -0700
    Re: Immutability and Python Neal Becker <ndbecker2@gmail.com> - 2012-10-30 16:45 -0400
      Re: Immutability and Python rusi <rustompmody@gmail.com> - 2012-10-30 20:21 -0700
  Re: Immutability and Python Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2012-11-08 08:38 +0100

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