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Re: __next__ and StopIteration

References (1 earlier) <54d94307$0$12998$c3e8da3$5496439d@news.astraweb.com> <CALwzidnufuFPX1K0QrAJZbEtS79xvOmhM7ZZ8t9dJSiKVvhUqQ@mail.gmail.com> <54D98A35.9060203@earthlink.net> <CAPTjJmrcbOYCuZCgiq9gStEG34nAvQ2gS-vZC-WUuAOPUV3hPw@mail.gmail.com> <54D9A22E.2070708@earthlink.net>
Date 2015-02-10 17:38 +1100
Subject Re: __next__ and StopIteration
From Chris Angelico <rosuav@gmail.com>
Newsgroups comp.lang.python
Message-ID <mailman.18597.1423550718.18130.python-list@python.org> (permalink)

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On Tue, Feb 10, 2015 at 5:16 PM, Charles Hixson
<charleshixsn@earthlink.net> wrote:
> Yes, rows and cols are lists, but I'm going to need to iterate through them
> more than once.  I'd rather do without a included class, but if a properly
> formed iterator can only be cycled through once, and if I understand
> properly that means I can't use the "class instance is it's own iterator"
> form.

When you write __iter__ as a generator function, what you actually
have is a factory for iterator objects. (Generators are iterators.)
When something calls __iter__ on your Grid, it gets back a brand new
iterator which is independent of every other iterator from that or any
other Grid, so you can iterate over the same Grid more than once.
You're not writing __next__ here, so you're not using the class
instance as its own iterator, which means that that consideration
doesn't apply.

ChrisA

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Thread

__next__ and StopIteration Charles Hixson <charleshixsn@earthlink.net> - 2015-02-09 11:14 -0800
  Re: __next__ and StopIteration Rob Gaddi <rgaddi@technologyhighland.invalid> - 2015-02-09 19:27 +0000
  Re: __next__ and StopIteration Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-02-10 10:30 +1100
    Re: __next__ and StopIteration Ian Kelly <ian.g.kelly@gmail.com> - 2015-02-09 16:56 -0700
      Re: __next__ and StopIteration Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-02-10 11:42 +1100
        Re: __next__ and StopIteration Chris Angelico <rosuav@gmail.com> - 2015-02-10 11:54 +1100
          Re: __next__ and StopIteration Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-02-10 12:11 +1100
            Re: __next__ and StopIteration Chris Angelico <rosuav@gmail.com> - 2015-02-10 12:58 +1100
        Re: __next__ and StopIteration Chris Kaynor <ckaynor@zindagigames.com> - 2015-02-09 16:59 -0800
          Re: __next__ and StopIteration Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-02-10 16:54 +1100
        Re: __next__ and StopIteration Ian Kelly <ian.g.kelly@gmail.com> - 2015-02-10 01:30 -0700
        Re: __next__ and StopIteration Chris Kaynor <ckaynor@zindagigames.com> - 2015-02-10 09:27 -0800
    Re: __next__ and StopIteration Charles Hixson <charleshixsn@earthlink.net> - 2015-02-09 20:33 -0800
    Re: __next__ and StopIteration Chris Angelico <rosuav@gmail.com> - 2015-02-10 15:46 +1100
    Re: __next__ and StopIteration Charles Hixson <charleshixsn@earthlink.net> - 2015-02-09 22:16 -0800
    Re: __next__ and StopIteration Chris Angelico <rosuav@gmail.com> - 2015-02-10 17:38 +1100
    Re: __next__ and StopIteration Ethan Furman <ethan@stoneleaf.us> - 2015-02-10 08:44 -0800
    Re: __next__ and StopIteration Ian Kelly <ian.g.kelly@gmail.com> - 2015-02-10 09:53 -0700
    Re: __next__ and StopIteration Ethan Furman <ethan@stoneleaf.us> - 2015-02-10 09:33 -0800

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