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Re: Encapsulation unpythonic?

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On Sat, 31 Aug 2013 12:46:52 +0100, Steven D'Aprano  
<steve+comp.lang.python@pearwood.info> wrote:

> # THIS DOES NOT HAPPEN IN PYTHON
> # or any other language, as far as I am aware
> x = 23
> y = x  # y now has the value 23
> x = 42  # change the value of the object  ### NOT SO! ###
> print y
> => prints 42

Not directly, but FORTRAN did (does?) allow you to achieve this  
oh-so-undesirable result indirectly.

FORTRAN passes arguments to functions and procedures by reference.  That  
includes passing constants, which effectively get put into hidden  
variables and passed across.  Changes to the "constant" parameters in the  
function can happen just as with any pass-by-reference, which would be  
fine if you promptly threw the constant away.  Unfortunately smart  
compilers used to (still do?) keep pools of these common constant  
"variables" around rather than creating new ones all the time, so changes  
to "constants" persisted.  Many's the poor natural scientist who was  
perplexed to find that 0 suddenly had the value 1!

-- 
Rhodri James *-* Wildebeest Herder to the Masses

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Encapsulation unpythonic? fsaldan1@gmail.com - 2013-08-17 05:26 -0700
  Re: Encapsulation unpythonic? Skip Montanaro <skip@pobox.com> - 2013-08-17 07:54 -0500
  Re: Encapsulation unpythonic? David <bouncingcats@gmail.com> - 2013-08-17 23:05 +1000
  Re: Encapsulation unpythonic? Chris Angelico <rosuav@gmail.com> - 2013-08-17 16:50 +0100
  Re: Encapsulation unpythonic? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-08-17 16:17 +0000
    Re: Encapsulation unpythonic? Joshua Landau <joshua@landau.ws> - 2013-08-18 18:15 +0100
      Re: Encapsulation unpythonic? Steven D'Aprano <steve@pearwood.info> - 2013-08-19 07:05 +0000
        Re: Encapsulation unpythonic? Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-08-19 18:57 -0400
        Re: Encapsulation unpythonic? random832@fastmail.us - 2013-08-21 12:52 -0400
          Re: Encapsulation unpythonic? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-08-22 02:06 +0000
        Re: Encapsulation unpythonic? Ian Kelly <ian.g.kelly@gmail.com> - 2013-08-21 16:02 -0600
  Re: Encapsulation unpythonic? Gary Herron <gary.herron@islandtraining.com> - 2013-08-17 13:16 -0700
  Re: Encapsulation unpythonic? Terry Reedy <tjreedy@udel.edu> - 2013-08-17 17:22 -0400
  Re: Encapsulation unpythonic? Chris Angelico <rosuav@gmail.com> - 2013-08-18 01:59 +0100
  Re: Encapsulation unpythonic? chaz2cry@gmail.com - 2013-08-22 19:12 -0700
  Re: Encapsulation unpythonic? Fabrice Pombet <fp2161@gmail.com> - 2013-08-30 10:43 -0700
    Re: Encapsulation unpythonic? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-08-31 02:35 +0000
      Re: Encapsulation unpythonic? Fabrice Pombet <fp2161@gmail.com> - 2013-08-30 23:07 -0700
        Re: Encapsulation unpythonic? Marco Buttu <marco.buttu@gmail.com> - 2013-08-31 08:49 +0200
        Re: Encapsulation unpythonic? Gary Herron <gherron@digipen.edu> - 2013-08-31 00:03 -0700
          Re: Encapsulation unpythonic? Fabrice Pombet <fp2161@gmail.com> - 2013-08-31 00:42 -0700
            Re: Encapsulation unpythonic? Fabrice Pombet <fp2161@gmail.com> - 2013-08-31 01:00 -0700
        Re: Encapsulation unpythonic? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-08-31 11:46 +0000
          Re: Encapsulation unpythonic? Ned Batchelder <ned@nedbatchelder.com> - 2013-08-31 08:41 -0400
            Re: Encapsulation unpythonic? Fabrice Pombet <fp2161@gmail.com> - 2013-08-31 05:49 -0700
          Re: Encapsulation unpythonic? Fabrice Pombet <fp2161@gmail.com> - 2013-08-31 05:57 -0700
            Re: Encapsulation unpythonic? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-09-01 08:10 +0000
              Re: Encapsulation unpythonic? Chris Angelico <rosuav@gmail.com> - 2013-09-01 18:21 +1000
                Re: Encapsulation unpythonic? Fabrice Pombet <fp2161@gmail.com> - 2013-09-01 03:09 -0700
                Re: Encapsulation unpythonic? Ethan Furman <ethan@stoneleaf.us> - 2013-09-01 11:42 -0700
                Re: Encapsulation unpythonic? Roy Smith <roy@panix.com> - 2013-09-01 15:13 -0400
                Re: Encapsulation unpythonic? Ethan Furman <ethan@stoneleaf.us> - 2013-09-01 13:33 -0700
                Re: Encapsulation unpythonic? Tim Delaney <timothy.c.delaney@gmail.com> - 2013-09-02 07:54 +1000
                Re: Encapsulation unpythonic? Roy Smith <roy@panix.com> - 2013-09-01 18:02 -0400
                Re: Encapsulation unpythonic? Ethan Furman <ethan@stoneleaf.us> - 2013-09-01 17:24 -0700
                Re: Encapsulation unpythonic? Roy Smith <roy@panix.com> - 2013-09-01 20:59 -0400
                Re: Encapsulation unpythonic? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-09-02 02:57 +0000
                Re: Encapsulation unpythonic? Ethan Furman <ethan@stoneleaf.us> - 2013-09-01 21:15 -0700
                Re: Encapsulation unpythonic? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-09-02 01:57 +0000
              Re: Encapsulation unpythonic? Ben Finney <ben+python@benfinney.id.au> - 2013-09-02 09:32 +1000
                Re: Encapsulation unpythonic? Roy Smith <roy@panix.com> - 2013-09-01 20:52 -0400
          Re: Encapsulation unpythonic? "Rhodri James" <rhodri@wildebst.demon.co.uk> - 2013-09-03 00:29 +0100
            Re: Encapsulation unpythonic? Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-09-03 22:41 -0400
        Re: Encapsulation unpythonic? Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-08-31 13:31 -0400
        Re: Encapsulation unpythonic? Tim Delaney <timothy.c.delaney@gmail.com> - 2013-09-01 03:47 +1000
    Re: Encapsulation unpythonic? 88888 Dihedral <dihedral88888@gmail.com> - 2013-09-02 14:43 -0700

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