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Re: Immutability and Python

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From Terry Reedy <tjreedy@udel.edu>
Subject Re: Immutability and Python
Date Mon, 29 Oct 2012 14:03:57 -0400
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On 10/29/2012 1:05 PM, andrea crotti wrote:

> I meant how do I create new immutables classes myself, I guess that's
> possible writing C extensions but I don't see in pure Python..

If you mean class with immutable instances, mutate new instances in 
__new__ instead of __init__ and write a custom .__setattr__ that 
prevents changes thereafter.

If you want the class itself to be immutable (after creation), write a 
custom metaclass.

You may also need to think about .__getattribute__, but I never studied 
the detail completely and have forgotten what I learned.

-- 
Terry Jan Reedy

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Thread

Re: Immutability and Python andrea crotti <andrea.crotti.0@gmail.com> - 2012-10-29 16:12 +0000
  Re: Immutability and Python Paul Rubin <no.email@nospam.invalid> - 2012-10-29 09:46 -0700
    Re: Immutability and Python andrea crotti <andrea.crotti.0@gmail.com> - 2012-10-29 17:05 +0000
      Re: Immutability and Python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-10-29 22:30 +0000
        Re: Immutability and Python Chris Kaynor <ckaynor@zindagigames.com> - 2012-10-29 15:45 -0700
          Re: Immutability and Python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-10-29 23:14 +0000
    Re: Re: Immutability and Python Evan Driscoll <driscoll@cs.wisc.edu> - 2012-10-29 12:58 -0500
    Re: Immutability and Python Terry Reedy <tjreedy@udel.edu> - 2012-10-29 14:03 -0400
    Re: Immutability and Python Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-10-29 14:25 -0400

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