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Re: Possible File iteration bug

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From Ian Kelly <ian.g.kelly@gmail.com>
Date Thu, 14 Jul 2011 14:00:06 -0600
Subject Re: Possible File iteration bug
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On Thu, Jul 14, 2011 at 1:46 PM, Billy Mays <noway@nohow.com> wrote:
> def getLines(f):
>    lines = []
>    for line in f:
>        lines.append(line)
>    return lines
>
> with open('/var/log/syslog', 'rb') as f:
>    lines = getLines(f)
>    # do some processing with lines
>    # /var/log/syslog gets updated in the mean time
>
>    # always returns an empty list, even though f has more data
>    lines = getLines(f)
>
>
>
>
> I found a workaround by adding f.seek(0,1) directly before the last
> getLines() call, but is this the expected behavior?  Calling f.tell() right
> after the first getLines() call shows that it isn't reset back to 0.  Is
> this correct or a bug?

This is expected.  Part of the iterator protocol is that once an
iterator raises StopIteration, it should continue to raise
StopIteration on subsequent next() calls.

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Thread

Possible File iteration bug Billy Mays <noway@nohow.com> - 2011-07-14 15:46 -0400
  Re: Possible File iteration bug Ian Kelly <ian.g.kelly@gmail.com> - 2011-07-14 14:00 -0600
    Re: Possible File iteration bug Billy Mays <noway@nohow.com> - 2011-07-14 16:15 -0400
      Re: Possible File iteration bug Hrvoje Niksic <hniksic@xemacs.org> - 2011-07-14 22:39 +0200
  Re: Possible File iteration bug Terry Reedy <tjreedy@udel.edu> - 2011-07-14 16:43 -0400
  Re: Possible File iteration bug "bruno.desthuilliers@gmail.com" <bruno.desthuilliers@gmail.com> - 2011-07-15 01:01 -0700
    Re: Possible File iteration bug Billy Mays <noway@nohow.com> - 2011-07-15 08:26 -0400
      Re: Possible File iteration bug Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2011-07-15 16:21 +0200
      Re: Possible File iteration bug Terry Reedy <tjreedy@udel.edu> - 2011-07-15 17:45 -0400
      Re: Possible File iteration bug Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-07-16 13:42 +1000
        Re: Possible File iteration bug Chris Angelico <rosuav@gmail.com> - 2011-07-16 14:07 +1000
        Re: Possible File iteration bug Cameron Simpson <cs@zip.com.au> - 2011-07-17 09:28 +1000
        Re: Possible File iteration bug Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2011-07-17 09:26 +0200
  Re: Possible File iteration bug Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2011-07-15 14:39 +0200
    Re: Possible File iteration bug Billy Mays <noway@nohow.com> - 2011-07-15 08:52 -0400
      Re: Possible File iteration bug Chris Angelico <rosuav@gmail.com> - 2011-07-15 22:58 +1000
      Re: Possible File iteration bug Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2011-07-15 16:28 +0200
        Re: Possible File iteration bug Billy Mays <81282ed9a88799d21e77957df2d84bd6514d9af6@myhashismyemail.com> - 2011-07-15 10:42 -0400
          Re: Possible File iteration bug Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2011-07-15 22:46 +0200
          Re: Possible File iteration bug Ethan Furman <ethan@stoneleaf.us> - 2011-07-15 14:20 -0700
          Re: Possible File iteration bug Terry Reedy <tjreedy@udel.edu> - 2011-07-15 17:47 -0400

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