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Groups > comp.lang.python > #48812

Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.]

From Roel Schroeven <roel@roelschroeven.net>
Subject Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.]
Date 2013-06-20 19:19 +0200
References (20 earlier) <kpnb7t$k63$1@news.ntua.gr> <HdmdncUNJIsSnV3MnZ2dnUVZ_oGdnZ2d@giganews.com> <kpp6v1$le7$1@news.grnet.gr> <51c022d5$0$29872$c3e8da3$5496439d@news.astraweb.com> <kppaih$jso$1@news.grnet.gr>
Newsgroups comp.lang.python
Message-ID <mailman.3634.1371748820.3114.python-list@python.org> (permalink)

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Νίκος schreef:
> Στις 18/6/2013 12:05 μμ, ο/η Steven D'Aprano έγραψε:
>> Names are *always* linked to objects, not to other names.
>>
>> a = []
>> b = a  # Now a and b refer to the same list
>> a = {} # Now a refers to a dict, and b refers to the same list as before
> 
> I see, thank you Steven.
> 
> But since this is a fact how do you create complicated data structures 
> that rely on various variables pointing one to another liek we did in 
> C++(cannot recall their names) ?

You almost never need to do that in Python. But if you really want to, 
out of curiosity, you can. For example, you could create a simple singly 
linked list like this:

 >>> class Node(object):
	def __init__(self, value):
		self.value = value
		self.next = None

		
 >>> first = Node(1)
 >>> second = Node(2)
 >>> first.next = second

You could iterate over it like this:

 >>> def iterate_linked_list(node):
	while node:
		yield node.value
		node = node.next

		
 >>> for v in iterate_linked_list(first):
	print v


-- 
"People almost invariably arrive at their beliefs not on the basis of
proof but on the basis of what they find attractive."
         -- Pascal Blaise

roel@roelschroeven.net

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Re: A certainl part of an if() structure never gets executed. Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-13 01:55 +0000
  Re: A certainl part of an if() structure never gets executed. Chris Angelico <rosuav@gmail.com> - 2013-06-13 12:03 +1000
  Re: A certainl part of an if() structure never gets executed. Kushal Kumaran <kushal.kumaran+python@gmail.com> - 2013-06-13 10:05 +0530
  Re: A certainl part of an if() structure never gets executed. Chris Angelico <rosuav@gmail.com> - 2013-06-13 14:39 +1000
  Re: A certainl part of an if() structure never gets executed. Νικόλαος Κούρας <support@superhost.gr> - 2013-06-13 08:36 +0300
  Re: A certainl part of an if() structure never gets executed. Νικόλαος Κούρας <support@superhost.gr> - 2013-06-13 10:11 +0300
    Re: A certainl part of an if() structure never gets executed. Sibylle Koczian <nulla.epistola@web.de> - 2013-06-13 14:22 +0200
      Re: A certainl part of an if() structure never gets executed. Νικόλαος Κούρας <support@superhost.gr> - 2013-06-13 17:26 +0300
        Re: A certainl part of an if() structure never gets executed. Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-14 01:14 +0000
          Re: A certainl part of an if() structure never gets executed. Nick the Gr33k <support@superhost.gr> - 2013-06-14 11:03 +0300
            Re: A certainl part of an if() structure never gets executed. Chris Angelico <rosuav@gmail.com> - 2013-06-14 18:23 +1000
            Re: A certainl part of an if() structure never gets executed. "R. Michael Weylandt" <michael.weylandt@gmail.com> - 2013-06-14 09:24 +0100
            Re: A certainl part of an if() structure never gets executed. Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-06-14 11:28 +0300
              Re: A certainl part of an if() structure never gets executed. Nick the Gr33k <support@superhost.gr> - 2013-06-14 11:41 +0300
                Re: A certainl part of an if() structure never gets executed. Chris Angelico <rosuav@gmail.com> - 2013-06-14 18:50 +1000
                Re: A certainl part of an if() structure never gets executed. Fábio Santos <fabiosantosart@gmail.com> - 2013-06-14 10:03 +0100
                Re: A certainl part of an if() structure never gets executed. Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-06-14 12:21 +0300
                Re: A certainl part of an if() structure never gets executed. Nick the Gr33k <support@superhost.gr> - 2013-06-14 12:44 +0300
                Re: A certainl part of an if() structure never gets executed. Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-06-14 15:40 +0300
                Re: A certainl part of an if() structure never gets executed. Nick the Gr33k <support@superhost.gr> - 2013-06-14 16:07 +0300
                Re: A certainl part of an if() structure never gets executed. Zero Piraeus <schesis@gmail.com> - 2013-06-14 09:48 -0400
                Re: A certainl part of an if() structure never gets executed. rusi <rustompmody@gmail.com> - 2013-06-14 07:05 -0700
                Re: A certainl part of an if() structure never gets executed. Nick the Gr33k <support@superhost.gr> - 2013-06-14 17:08 +0300
                Re: A certainl part of an if() structure never gets executed. Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-14 16:31 +0000
                Re: A certainl part of an if() structure never gets executed. Nick the Gr33k <support@superhost.gr> - 2013-06-14 19:56 +0300
                Re: A certainl part of an if() structure never gets executed. Chris Angelico <rosuav@gmail.com> - 2013-06-15 03:18 +1000
                Re: A certainl part of an if() structure never gets executed. Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-06-14 21:17 +0300
                Re: A certainl part of an if() structure never gets executed. Larry Hudson <orgnut@yahoo.com> - 2013-06-14 22:27 -0700
                Re: A certainl part of an if() structure never gets executed. Nick the Gr33k <support@superhost.gr> - 2013-06-15 11:39 +0300
                Re: A certainl part of an if() structure never gets executed. Lele Gaifax <lele@metapensiero.it> - 2013-06-15 11:54 +0200
                Re: A certainl part of an if() structure never gets executed. Nick the Gr33k <support@superhost.gr> - 2013-06-15 16:07 +0300
                Re: A certainl part of an if() structure never gets executed. Michael Torrie <torriem@gmail.com> - 2013-06-15 09:53 -0600
                Re: A certainl part of an if() structure never gets executed. Nick the Gr33k <support@superhost.gr> - 2013-06-15 19:18 +0300
                Re: A certainl part of an if() structure never gets executed. Michael Torrie <torriem@gmail.com> - 2013-06-15 11:45 -0600
                Re: A certainl part of an if() structure never gets executed. Denis McMahon <denismfmcmahon@gmail.com> - 2013-06-16 06:32 +0000
                Re: A certainl part of an if() structure never gets executed. Nick the Gr33k <support@superhost.gr> - 2013-06-16 11:07 +0300
                Re: A certainl part of an if() structure never gets executed. Denis McMahon <denismfmcmahon@gmail.com> - 2013-06-16 09:22 +0000
                Re: A certainl part of an if() structure never gets executed. Nick the Gr33k <support@superhost.gr> - 2013-06-16 12:59 +0300
                Re: A certainl part of an if() structure never gets executed. "R. Michael Weylandt" <michael.weylandt@gmail.com> - 2013-06-16 11:42 +0100
                Re: A certainl part of an if() structure never gets executed. Ferrous Cranus <support@superhost.gr> - 2013-06-16 14:06 +0300
                Re: A certainl part of an if() structure never gets executed. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-06-16 12:26 +0100
                Re: A certainl part of an if() structure never gets executed. YBM <ybmess@nooos.fr.invalid> - 2013-06-16 14:00 +0200
                Re: A certainl part of an if() structure never gets executed. "R. Michael Weylandt" <michael.weylandt@gmail.com> - 2013-06-16 13:04 +0100
                Re: A certainl part of an if() structure never gets executed. Ferrous Cranus <support@superhost.gr> - 2013-06-16 16:38 +0300
                Re: A certainl part of an if() structure never gets executed. "R. Michael Weylandt" <michael.weylandt@gmail.com> - 2013-06-16 19:50 +0100
                Re: A certainl part of an if() structure never gets executed. Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-06-16 11:52 +0100
                Re: A certainl part of an if() structure never gets executed. Denis McMahon <denismfmcmahon@gmail.com> - 2013-06-16 10:51 +0000
                Compiling vs interpreting [was Re: A certainl part of an if() structure never gets executed.] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-16 12:07 +0000
                Re: Compiling vs interpreting [was Re: A certainl part of an if() structure never gets executed.] Mark Janssen <dreamingforward@gmail.com> - 2013-06-16 12:31 -0700
                Re: Compiling vs interpreting [was Re: A certainl part of an if() structure never gets executed.] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-16 20:02 +0000
                Re: Compiling vs interpreting [was Re: A certainl part of an if() structure never gets executed.] Chris Angelico <rosuav@gmail.com> - 2013-06-17 08:26 +1000
                Re: Compiling vs interpreting [was Re: A certainl part of an if() structure never gets executed.] Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-06-16 23:13 -0400
                Re: A certainl part of an if() structure never gets executed. Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-06-16 14:13 +0300
                Re: A certainl part of an if() structure never gets executed. Ferrous Cranus <support@superhost.gr> - 2013-06-16 16:47 +0300
                Re: A certainl part of an if() structure never gets executed. "R. Michael Weylandt" <michael.weylandt@gmail.com> - 2013-06-16 19:53 +0100
                Re: A certainl part of an if() structure never gets executed. Νίκος <support@superhost.gr> - 2013-06-17 08:17 +0300
                Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-17 06:51 +0000
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Simpleton <support@superhost.gr> - 2013-06-17 14:34 +0300
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Michael Torrie <torriem@gmail.com> - 2013-06-17 05:58 -0600
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Simpleton <support@superhost.gr> - 2013-06-17 18:50 +0300
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Larry Hudson <orgnut@yahoo.com> - 2013-06-17 23:39 -0700
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-18 07:24 +0000
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Νίκος <support@superhost.gr> - 2013-06-18 11:49 +0300
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-18 09:05 +0000
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Νίκος <support@superhost.gr> - 2013-06-18 12:51 +0300
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Chris Angelico <rosuav@gmail.com> - 2013-06-18 20:22 +1000
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Michael Torrie <torriem@gmail.com> - 2013-06-19 23:16 -0600
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-20 05:48 +0000
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Michael Torrie <torriem@gmail.com> - 2013-06-20 00:01 -0600
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] 88888 Dihedral <dihedral88888@gmail.com> - 2013-06-26 01:18 -0700
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Michael Torrie <torriem@gmail.com> - 2013-06-19 23:44 -0600
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Roel Schroeven <roel@roelschroeven.net> - 2013-06-20 19:19 +0200
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Terry Reedy <tjreedy@udel.edu> - 2013-06-17 10:22 -0400
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Simpleton <support@superhost.gr> - 2013-06-17 18:55 +0300
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Joel Goldstick <joel.goldstick@gmail.com> - 2013-06-17 12:26 -0400
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Benjamin Kaplan <benjamin.kaplan@case.edu> - 2013-06-17 09:23 -0700
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Νίκος <support@superhost.gr> - 2013-06-17 20:17 +0300
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Terry Reedy <tjreedy@udel.edu> - 2013-06-17 18:16 -0400
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-17 23:09 +0000
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Νίκος <support@superhost.gr> - 2013-06-18 02:26 +0300
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-18 00:41 +0000
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Dave Angel <davea@davea.name> - 2013-06-17 21:06 -0400
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-18 02:42 +0000
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Dave Angel <davea@davea.name> - 2013-06-18 00:12 -0400
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-18 06:04 +0000
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-18 02:38 +0000
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-18 02:46 +0000
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-06-17 21:34 -0400
                Re: Variables versus name bindings [Re: A certainl part of an if() structure never gets executed.] Marcin Szamotulski <mszamot@gmail.com> - 2013-06-18 04:22 +0100
                Re: A certainl part of an if() structure never gets executed. Michael Weylandt <michael.weylandt@gmail.com> - 2013-06-17 07:56 +0100
                Re: A certainl part of an if() structure never gets executed. Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-16 12:50 +0000
                OT: C vs Python terminology (was: A certainl part of an if() structure never gets executed) Andreas Perstinger <andipersti@gmail.com> - 2013-06-16 13:22 +0200
                Re: OT: C vs Python terminology Dave Angel <davea@davea.name> - 2013-06-16 08:55 -0400
                Re: OT: C vs Python terminology Andreas Perstinger <andipersti@gmail.com> - 2013-06-16 17:02 +0200
                Re: OT: C vs Python terminology Dave Angel <davea@davea.name> - 2013-06-16 21:58 -0400
            Re: A certainl part of an if() structure never gets executed. "R. Michael Weylandt" <michael.weylandt@gmail.com> - 2013-06-14 09:28 +0100
            Re: A certainl part of an if() structure never gets executed. Fábio Santos <fabiosantosart@gmail.com> - 2013-06-14 09:35 +0100
            Re: A certainl part of an if() structure never gets executed. Nick the Gr33k <support@superhost.gr> - 2013-06-14 11:44 +0300
              Re: A certainl part of an if() structure never gets executed. Chris Angelico <rosuav@gmail.com> - 2013-06-14 18:57 +1000
                Re: A certainl part of an if() structure never gets executed. Nick the Gr33k <support@superhost.gr> - 2013-06-14 12:00 +0300
                Re: A certainl part of an if() structure never gets executed. Chris Angelico <rosuav@gmail.com> - 2013-06-14 19:12 +1000
                Re: A certainl part of an if() structure never gets executed. Nick the Gr33k <support@superhost.gr> - 2013-06-14 12:47 +0300
                Re: A certainl part of an if() structure never gets executed. Tim Roberts <timr@probo.com> - 2013-06-15 18:55 -0700
                Re: A certainl part of an if() structure never gets executed. Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-16 05:09 +0000
                Re: A certainl part of an if() structure never gets executed. Nick the Gr33k <support@superhost.gr> - 2013-06-16 11:20 +0300
                Re: A certainl part of an if() structure never gets executed. Tim Roberts <timr@probo.com> - 2013-06-18 22:08 -0700
                Re: A certainl part of an if() structure never gets executed. Dave Angel <davea@davea.name> - 2013-06-19 01:42 -0400
                Re: A certainl part of an if() structure never gets executed. Chris Angelico <rosuav@gmail.com> - 2013-06-19 17:14 +1000
                Re: A certainl part of an if() structure never gets executed. Νίκος <support@superhost.gr> - 2013-06-19 10:49 +0300
                Re: A certainl part of an if() structure never gets executed. Dave Angel <davea@davea.name> - 2013-06-19 04:06 -0400
                Re: A certainl part of an if() structure never gets executed. Chris Angelico <rosuav@gmail.com> - 2013-06-19 18:21 +1000
                Re: A certainl part of an if() structure never gets executed. Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-19 08:55 +0000
                Re: A certainl part of an if() structure never gets executed. Chris Angelico <rosuav@gmail.com> - 2013-06-19 19:14 +1000
                Re: A certainl part of an if() structure never gets executed. Grant Edwards <invalid@invalid.invalid> - 2013-06-14 14:38 +0000
              Re: A certainl part of an if() structure never gets executed. Fábio Santos <fabiosantosart@gmail.com> - 2013-06-14 10:05 +0100

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