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Re: What is xrange?

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Date Fri, 29 Jul 2011 22:31:36 +0200
From Thomas Jollans <t@jollybox.de>
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Subject Re: What is xrange?
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On 29/07/11 21:36, Billy Mays wrote:
> Is xrange not a generator?  I know it doesn't return a tuple or list,
> so what exactly is it?  Y doesn't ever complete, but x does.
>
> x = (i for i in range(10))
> y = xrange(10)
>
> print "===X==="
> while True:
>     for i in x:
>         print i
>         break
>     else:
>         break
>
> print "===Y==="
> while True:
>     for i in y:
>         print i
>         break
>     else:
>         break

Every for loop calls gets a new iterator from the object you're
iterating over. (__iter__) -- Apparently, xrange is implemented in such
a way (as are lists) that you can iterate over the object many times,
while each generator object (and how could it be otherwise can only be
iterated over once. What is xrange(foo)? It is an object that supports
list-like indices, the iterator protocol, and probably a few other
things that you will find in the stdlib docs. Generators also support
the iterator protocol, but that's about as far as the similarity goes
(in general)

 - Thomas

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Thread

What is xrange? Billy Mays <noway@nohow.com> - 2011-07-29 15:36 -0400
  Re: What is xrange? harrismh777 <harmar@member.fsf.org> - 2011-07-29 14:47 -0500
  Re: What is xrange? Thomas Jollans <t@jollybox.de> - 2011-07-29 22:31 +0200
  Re: What is xrange? Jerry Hill <malaclypse2@gmail.com> - 2011-07-29 16:36 -0400
  Re: What is xrange? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-07-30 11:22 +1000
    Re: What is xrange? Brian Blais <bblais@bryant.edu> - 2011-07-30 06:23 -0400
      Re: What is xrange? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-07-30 21:36 +1000
        Re: What is xrange? Brian Blais <bblais@bryant.edu> - 2011-07-30 09:46 -0400
        Re: What is xrange? Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2011-07-30 17:06 -0700
        Re: What is xrange? Chris Angelico <rosuav@gmail.com> - 2011-07-31 01:10 +0100
        Re: What is xrange? Ethan Furman <ethan@stoneleaf.us> - 2011-07-30 23:42 -0700
      Re: What is xrange? Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2011-07-31 12:18 +1200

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