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Re: Strange range

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From Marko Rauhamaa <marko@pacujo.net>
Newsgroups comp.lang.python
Subject Re: Strange range
Date Fri, 01 Apr 2016 17:12:49 +0300
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Steven D'Aprano <steve@pearwood.info>:

> On Sat, 2 Apr 2016 12:15 am, Marko Rauhamaa wrote:
>> Note to self: range(10) is an iterator factory, not an iterator.
>
> Incorrect. range is a lazy sequence.

Incorrect. You and I agree.

> You can think of range as equivalent to something close to this:
>
> class Range(object):
>     def __init__(self, start, end, step=1):
>         self.start = start
>         self.end = end
>         self.step = step
>
>     def __getitem__(self, index):
>         value = self.start + (index-1)*self.step
>         if value < self.end:
>             return value
>         raise IndexError
>
>     def __iter__(self):
>         try:
>             index = 0
>             while True:
>                 yield self[index]
>                 index += 1
>         except IndexError:
>             return

Yes, I realize it now. I had thought it was:

    def range(start, end=None, step=1):
        if end is None:
            start, end = 0, start
        i = start
        while step * (end - i) > 0:
            yield i
            i += step


Marko

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Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 16:15 +0300
  Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-02 00:24 +1100
  Re: Strange range Steven D'Aprano <steve@pearwood.info> - 2016-04-02 00:26 +1100
    Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 17:12 +0300
      Re: Strange range Random832 <random832@fastmail.com> - 2016-04-01 10:39 -0400
    Re: Strange range Fabien <fabien.maussion@gmail.com> - 2016-04-01 16:16 +0200
      Re: Strange range Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-04-01 17:28 +0300
      Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-02 01:31 +1100
        Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 17:34 +0300
          Re: Strange range Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-04-01 17:44 +0300
          Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-02 01:45 +1100
            Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 18:43 +0300
          Re: Strange range Erik <python@lucidity.plus.com> - 2016-04-01 20:58 +0100
            Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 23:14 +0300
              Re: Strange range Rob Gaddi <rgaddi@highlandtechnology.invalid> - 2016-04-01 20:21 +0000
                Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 23:44 +0300
              Re: Strange range Steven D'Aprano <steve@pearwood.info> - 2016-04-02 21:09 +1100
                Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-02 13:48 +0300
          Re: Strange range Ned Batchelder <ned@nedbatchelder.com> - 2016-04-02 12:47 -0700
            Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-02 23:44 +0300
              Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-03 07:05 +1000
                Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-03 00:40 +0300
                Re: Strange range Ned Batchelder <ned@nedbatchelder.com> - 2016-04-02 14:50 -0700
                Re: Strange range Stephen Hansen <me+python@ixokai.io> - 2016-04-02 23:43 -0700
                Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-03 09:58 +0300
                Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-03 17:10 +1000
                Re: Strange range Ethan Furman <ethan@stoneleaf.us> - 2016-04-03 09:28 -0700
                Re: Strange range Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-04-04 13:21 +0100
                Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-03 17:08 +1000
              Re: Strange range Steven D'Aprano <steve@pearwood.info> - 2016-04-03 14:43 +1000
                Re: Strange range Random832 <random832@fastmail.com> - 2016-04-03 01:20 -0400
                Re: Strange range Steven D'Aprano <steve@pearwood.info> - 2016-04-03 15:28 +1000
      Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 17:32 +0300
  Re: Strange range Random832 <random832@fastmail.com> - 2016-04-01 10:42 -0400
  Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-02 01:50 +1100
  Re: Strange range Ian Kelly <ian.g.kelly@gmail.com> - 2016-04-01 08:52 -0600

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