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Re: Closures in leu of pointers?

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From Peter Otten <__peter__@web.de>
Subject Re: Closures in leu of pointers?
Date Sat, 29 Jun 2013 14:12:57 +0200
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Xref csiph.com comp.lang.python:49414

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cts.private.yahoo@gmail.com wrote:

> As for python 3 ... "nonlocal"?  I see I'm not alone in picking obnoxious
> names ...

tous chez...

> Alas, one reason it's a weak workaround is that it doesn't work - at
> least, not how I wish it would:

> $ cat ptrs
> 
> x = 34
> 
> def p1 (a1):
> 
>     a1[0] += 12
>     
> p1 ([x])
> 
> print (x)
> 
> $ python ptrs
> 34

That doesn't work with 'nonlocal' either. 

You can compare Python's names with (automatically dereferenced and 
garbage-collected) pointers, but there is no way to have a name refer to 
another name. The C-like

f(var *value)
{
    value = ...
}

is the only way to pass a variable in Python. There is no way to emulate

f(var **value)
{
   *value = ...
}

When this came up a few days ago I linked to

http://learntofish.wordpress.com/2012/01/09/call-by-object-reference-call-by-sharing/

but I was actually looking for the classic, so there:

http://python.net/~mwh/hacks/objectthink.html

PS: If you're reading this and love the French language -- I am deeply sorry 
for the pain I'm causing you...

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Thread

Closures in leu of pointers? cts.private.yahoo@gmail.com - 2013-06-29 02:34 -0700
  Re: Closures in leu of pointers? Fábio Santos <fabiosantosart@gmail.com> - 2013-06-29 10:42 +0100
  Re: Closures in leu of pointers? Peter Otten <__peter__@web.de> - 2013-06-29 12:01 +0200
    Re: Closures in leu of pointers? cts.private.yahoo@gmail.com - 2013-06-29 04:21 -0700
      Re: Closures in leu of pointers? cts.private.yahoo@gmail.com - 2013-06-29 04:44 -0700
        Re: Closures in leu of pointers? Peter Otten <__peter__@web.de> - 2013-06-29 14:12 +0200
          Re: Closures in leu of pointers? cts.private.yahoo@gmail.com - 2013-06-29 05:26 -0700
            Re: Closures in leu of pointers? Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-06-29 15:37 +0100
              Re: Closures in leu of pointers? cts.private.yahoo@gmail.com - 2013-06-29 07:48 -0700
        Re: Closures in leu of pointers? Michael Torrie <torriem@gmail.com> - 2013-06-29 07:56 -0600
        Re: Closures in leu of pointers? Michael Torrie <torriem@gmail.com> - 2013-06-29 12:36 -0600
      Re: Closures in leu of pointers? Michael Torrie <torriem@gmail.com> - 2013-06-29 08:02 -0600
      Re: Closures in leu of pointers? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-29 19:02 +0200
        Re: Closures in leu of pointers? rusi <rustompmody@gmail.com> - 2013-06-29 10:33 -0700
          Re: Closures in leu of pointers? cts.private.yahoo@gmail.com - 2013-06-29 11:37 -0700
            Re: Closures in leu of pointers? Michael Torrie <torriem@gmail.com> - 2013-06-29 12:58 -0600
            Re: Closures in leu of pointers? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-29 18:59 +0000
        Re: Closures in leu of pointers? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-29 18:51 +0000
          Re: Closures in leu of pointers? Michael Torrie <torriem@gmail.com> - 2013-06-29 13:04 -0600
          Re: Closures in leu of pointers? rusi <rustompmody@gmail.com> - 2013-06-29 12:11 -0700
      Re: Closures in leu of pointers? Michael Torrie <torriem@gmail.com> - 2013-06-29 12:35 -0600
        Re: Closures in leu of pointers? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-29 19:19 +0000
          Re: Closures in leu of pointers? Tim Chase <tim@thechases.com> - 2013-06-29 14:42 -0500
            Re: Closures in leu of pointers? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-30 01:41 +0000
          Re: Closures in leu of pointers? Joshua Landau <joshua.landau.ws@gmail.com> - 2013-06-29 21:02 +0100
          Re: Closures in leu of pointers? Michael Torrie <torriem@gmail.com> - 2013-06-29 16:02 -0600
      Re: Closures in leu of pointers? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-29 18:45 +0000
        Re: Closures in leu of pointers? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-29 19:00 +0000
        Re: Closures in leu of pointers? cts.private.yahoo@gmail.com - 2013-06-29 12:20 -0700
          Re: Closures in leu of pointers? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-29 19:33 +0000
            Re: Closures in leu of pointers? cts.private.yahoo@gmail.com - 2013-06-29 12:34 -0700
            Re: Closures in leu of pointers? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-29 13:47 -0600
            Re: Closures in leu of pointers? Terry Reedy <tjreedy@udel.edu> - 2013-06-29 16:53 -0400
              Re: Closures in leu of pointers? rusi <rustompmody@gmail.com> - 2013-06-30 01:56 -0700
                Re: Closures in leu of pointers? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-30 11:22 +0000
                Re: Closures in leu of pointers? rusi <rustompmody@gmail.com> - 2013-06-30 04:42 -0700
            Re: Closures in leu of pointers? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-29 15:21 -0600
              Re: Closures in leu of pointers? cts.private.yahoo@gmail.com - 2013-06-29 14:30 -0700
            Re: Closures in leu of pointers? Terry Reedy <tjreedy@udel.edu> - 2013-06-30 00:32 -0400
            Re: Closures in leu of pointers? Chris Angelico <rosuav@gmail.com> - 2013-06-30 15:08 +1000
              Re: Closures in leu of pointers? rusi <rustompmody@gmail.com> - 2013-06-30 00:36 -0700
            Re: Closures in leu of pointers? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-29 23:46 -0600
              Re: Closures in leu of pointers? alex23 <wuwei23@gmail.com> - 2013-07-01 14:57 +1000
              Re: Closures in leu of pointers? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-01 07:36 +0000
            Re: Closures in leu of pointers? Chris Angelico <rosuav@gmail.com> - 2013-06-30 15:59 +1000
            Re: Closures in leu of pointers? Terry Reedy <tjreedy@udel.edu> - 2013-06-30 02:11 -0400
            Re: Closures in leu of pointers? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-30 00:24 -0600
          Re: Closures in leu of pointers? Michael Torrie <torriem@gmail.com> - 2013-06-29 16:03 -0600
      Re: Closures in leu of pointers? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-29 13:23 -0600
      Re: Closures in leu of pointers? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-30 12:07 +0200
      Re: Closures in leu of pointers? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-30 11:13 -0600
      Re: Closures in leu of pointers? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-30 11:18 -0600

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