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Re: Iterator, modify data in loop body

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Date Wed, 17 Sep 2014 01:19:28 +1000
Subject Re: Iterator, modify data in loop body
From Chris Angelico <rosuav@gmail.com>
Cc "python-list@python.org" <python-list@python.org>
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On Tue, Sep 16, 2014 at 6:49 PM, Thomas Rachel
<nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de>
wrote:
> Am 13.09.2014 09:22 schrieb Chris Angelico:
>
>> In that case, don't iterate over the list at all. Do something like this:
>>
>> while lst:
>>      element = lst.pop(0)
>>      # work with element
>>      lst.append(new_element)
>
>
> And if you don't like that, define a
>
> def iter_pop(lst):
>     while lst:
>         yield lst.pop(0)
>
> and you can do
>
>     for element in iter_pop(lst):

But that's exactly the same thing, with another level of indirection.
It certainly isn't the advantage you'd expect from an iterator, namely
that it simply stores a marker that gets advanced to the next element.
Popping the 0th element is costly, wrapping it into an iterator
conceals that.

ChrisA

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Thread

Iterator, modify data in loop body Michael Welle <mwe012008@gmx.net> - 2014-09-13 08:09 +0200
  Re: Iterator, modify data in loop body Chris Angelico <rosuav@gmail.com> - 2014-09-13 16:22 +1000
    Re: Iterator, modify data in loop body Michael Welle <mwe012008@gmx.net> - 2014-09-13 09:01 +0200
      Re: Iterator, modify data in loop body Chris Angelico <rosuav@gmail.com> - 2014-09-13 17:22 +1000
        Re: Iterator, modify data in loop body Michael Welle <mwe012008@gmx.net> - 2014-09-13 09:39 +0200
          Re: Iterator, modify data in loop body Ian Kelly <ian.g.kelly@gmail.com> - 2014-09-13 09:27 -0600
            Re: Iterator, modify data in loop body Michael Welle <mwe012008@gmx.net> - 2014-09-13 18:58 +0200
          Re: Iterator, modify data in loop body Chris Angelico <rosuav@gmail.com> - 2014-09-14 01:32 +1000
        Re: Iterator, modify data in loop body Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2014-09-16 10:49 +0200
          Re: Iterator, modify data in loop body Chris Angelico <rosuav@gmail.com> - 2014-09-17 01:19 +1000
  Re: Iterator, modify data in loop body Peter Otten <__peter__@web.de> - 2014-09-13 09:34 +0200
    Re: Iterator, modify data in loop body Michael Welle <mwe012008@gmx.net> - 2014-09-13 09:55 +0200

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