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Re: __init__ is the initialiser

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From Dennis Lee Bieber <wlfraed@ix.netcom.com>
Subject Re: __init__ is the initialiser
Date Mon, 03 Feb 2014 19:38:33 -0500
Organization IISS Elusive Unicorn
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On Mon, 3 Feb 2014 10:44:21 -0700, Ian Kelly <ian.g.kelly@gmail.com>
declaimed the following:

>
>If Python interns the byte objects though, won't overwriting them lead
>to subtle bugs later on as Python attempts to reuse them?  They may
>even be reused already from earlier byte objects with the same values,
>that may or may not still have references.

	I suspect Python won't intern the /array/ of bytes; just the references
to the individual values -- and overwriting will change the references to
different interned values. I doubt the interning of the individual values
will appear in the order of the initial key -- and even if they did, any
duplicate bytes in the initial key would start by referencing the first
occurrence, while the randomization process would pick other interned
location.

>>> import array
>>> key = array.array("i", [1, 2, 3, 1, 3, 4])
>>> key
array('i', [1, 2, 3, 1, 3, 4])
>>> for i in key:
... 	print id(i)
... 	
3029624
3029600
3029576
3029624
3029576
3029552
>>> for i in range(len(key)):
... 	key[i] = key[i] * 3 - 2	#imagine this is a random production
... 	
>>> for i in key:
... 	print id(i)
... 
3029624
3029552
3029480
3029624
3029480
3029408
>>> key
array('i', [1, 4, 7, 1, 7, 10])
>>> 

	Interesting: the IDs for 1, 2, 3, 4 -- if memory addresses -- are in
descending address order. And that continues through the replacement
values.

-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
    wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/

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Thread

Re: __init__ is the initialiser Terry Reedy <tjreedy@udel.edu> - 2014-01-31 22:16 -0500
  Re: __init__ is the initialiser Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-01 05:23 +0000
    Re: __init__ is the initialiser Roy Smith <roy@panix.com> - 2014-02-01 00:25 -0500
      Re: __init__ is the initialiser Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-02-03 12:15 +1300
        Re: __init__ is the initialiser Chris Angelico <rosuav@gmail.com> - 2014-02-03 10:27 +1100
          Re: __init__ is the initialiser Roy Smith <roy@panix.com> - 2014-02-02 18:40 -0500
            Re: __init__ is the initialiser Chris Angelico <rosuav@gmail.com> - 2014-02-03 11:07 +1100
            Re: __init__ is the initialiser Devin Jeanpierre <jeanpierreda@gmail.com> - 2014-02-02 17:24 -0800
            Re: __init__ is the initialiser Chris Angelico <rosuav@gmail.com> - 2014-02-03 12:37 +1100
            Re: __init__ is the initialiser Devin Jeanpierre <jeanpierreda@gmail.com> - 2014-02-02 17:54 -0800
            Re: __init__ is the initialiser Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-02-03 08:44 -0500
            Re: __init__ is the initialiser Nicholas Cole <nicholas.cole@gmail.com> - 2014-02-03 13:50 +0000
            Re: __init__ is the initialiser Ian Kelly <ian.g.kelly@gmail.com> - 2014-02-03 10:44 -0700
            Re: __init__ is the initialiser Chris Angelico <rosuav@gmail.com> - 2014-02-04 04:57 +1100
            Re: __init__ is the initialiser Nicholas Cole <nicholas.cole@gmail.com> - 2014-02-03 19:57 +0000
            Re: __init__ is the initialiser Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-02-03 19:38 -0500
        Re: __init__ is the initialiser Dave Angel <davea@davea.name> - 2014-02-02 19:35 -0500
          Re: __init__ is the initialiser Roy Smith <roy@panix.com> - 2014-02-02 19:45 -0500
            Re: __init__ is the initialiser Dave Angel <davea@davea.name> - 2014-02-02 22:14 -0500
            Re: __init__ is the initialiser Skip Montanaro <skip@pobox.com> - 2014-02-02 21:15 -0600
            Re: __init__ is the initialiser Dave Angel <davea@davea.name> - 2014-02-03 00:06 -0500
              Re: __init__ is the initialiser Roy Smith <roy@panix.com> - 2014-02-03 00:12 -0500
                Re: __init__ is the initialiser Chris Angelico <rosuav@gmail.com> - 2014-02-03 16:49 +1100
                Re: __init__ is the initialiser Ethan Furman <ethan@stoneleaf.us> - 2014-02-02 21:34 -0800
    Re: __init__ is the initialiser Rustom Mody <rustompmody@gmail.com> - 2014-01-31 21:31 -0800

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