Re: open() and EOFError

From	Roy Smith <roy@panix.com>
Newsgroups	comp.lang.python
Subject	Re: open() and EOFError
Date	2014-07-07 08:46 -0400
Organization	PANIX Public Access Internet and UNIX, NYC
Message-ID	<roy-895695.08463307072014@news.panix.com> (permalink)
References	<53ba11fc$0$29985$c3e8da3$5496439d@news.astraweb.com> <c1uo2eF60gfU1@mid.individual.net> <53ba538d$0$2926$c3e8da3$76491128@news.astraweb.com> <mailman.11587.1404735570.18130.python-list@python.org>

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In article <mailman.11587.1404735570.18130.python-list@python.org>,
 Chris Angelico <rosuav@gmail.com> wrote:

> On Mon, Jul 7, 2014 at 6:00 PM, Steven D'Aprano <steve@pearwood.info> wrote:
> > How do people feel about code like this?
> >
> > try:
> >     name = input("Enter file name, or Ctrl-D to exit")
> >     # On Windows, use Ctrl-Z [enter] instead.
> >     fp = open(name)
> > except EOFError:
> >     sys.exit()
> > except IOError:
> >     handle_bad_file(name)
> > else:
> >     handle_good_file(fp)
> 
> Just thought of something. It's possible for input() to raise IOError,
> if I'm not mistaken; consider redirection, for instance. In that case,
> you would definitely want to split the try blocks, so you don't try to
> "handle_bad_file" when no name was entered. (As Dave says, name hasn't
> been assigned at that point, although I'd be less concerned about a
> possible cascaded NameError than about a possible handle_bad_file()
> with the previous name, if this is in a loop.)
> 
> ChrisA

My latest and greatest IOError horror story....

A guy here at work was running a Python job that was taking many days to 
complete.  He was running it on one of our production machines where we 
continually push out new releases, and clean up old ones after a few 
days.  Well, his job took longer than a few days and the directory 
containing the virtualenv he was running out of was deleted.  This 
didn't bother anything until several days later, when something deep 
inside some library function needed to open a (now missing) data file.  
Which of course, generated an IOError, which was caught in some 
unexpected place, causing all sorts of confusion trying to figure out 
WTF happened.

We've since modified our cleanup script to run lsof and skip purging any 
releases which are still in use :-)

Thread

open() and EOFError Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-07-07 03:20 +0000
  Re: open() and EOFError Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-07-07 17:04 +1200
    Re: open() and EOFError Steven D'Aprano <steve@pearwood.info> - 2014-07-07 08:00 +0000
      Re: open() and EOFError Chris Angelico <rosuav@gmail.com> - 2014-07-07 18:09 +1000
      Re: open() and EOFError Dave Angel <davea@davea.name> - 2014-07-07 08:14 -0400
      Re: open() and EOFError Chris Angelico <rosuav@gmail.com> - 2014-07-07 22:19 +1000
        Re: open() and EOFError Roy Smith <roy@panix.com> - 2014-07-07 08:46 -0400
          Re: open() and EOFError Chris Angelico <rosuav@gmail.com> - 2014-07-07 22:58 +1000
            Re: open() and EOFError Roy Smith <roy@panix.com> - 2014-07-07 20:26 -0400
          Re: open() and EOFError Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-07-08 09:50 +1200
        Re: open() and EOFError Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-07-07 15:45 +0000
          Re: open() and EOFError Chris Angelico <rosuav@gmail.com> - 2014-07-08 01:53 +1000
          Re: open() and EOFError Marko Rauhamaa <marko@pacujo.net> - 2014-07-07 19:08 +0300
            Re: open() and EOFError Marko Rauhamaa <marko@pacujo.net> - 2014-07-07 19:12 +0300
      Re: open() and EOFError Roy Smith <roy@panix.com> - 2014-07-07 08:39 -0400
        Re: open() and EOFError Chris Angelico <rosuav@gmail.com> - 2014-07-07 22:55 +1000
          Re: open() and EOFError Roy Smith <roy@panix.com> - 2014-07-07 20:28 -0400
        Re: open() and EOFError Terry Reedy <tjreedy@udel.edu> - 2014-07-07 14:49 -0400
          Re: open() and EOFError Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-07-08 10:04 +1200
            Re: open() and EOFError Grant Edwards <invalid@invalid.invalid> - 2014-07-08 14:19 +0000
              Re: open() and EOFError Terry Reedy <tjreedy@udel.edu> - 2014-07-08 11:08 -0400
              Re: open() and EOFError Tim Chase <python.list@tim.thechases.com> - 2014-07-08 10:20 -0500
              Re: open() and EOFError Chris Angelico <rosuav@gmail.com> - 2014-07-09 01:24 +1000
              Re: open() and EOFError Tim Chase <python.list@tim.thechases.com> - 2014-07-08 10:46 -0500
                Re: open() and EOFError Roy Smith <roy@panix.com> - 2014-07-08 21:05 -0400
                Re: open() and EOFError Anssi Saari <as@sci.fi> - 2014-07-10 22:40 +0300
              Re: open() and EOFError Chris Angelico <rosuav@gmail.com> - 2014-07-09 01:49 +1000
              Re: ^D vs ^Z as EOF and DOS dinosaurs talking (was: open() and EOFError) Tim Chase <python.list@tim.thechases.com> - 2014-07-08 10:57 -0500
                Re: ^D vs ^Z as EOF and DOS dinosaurs talking (was: open() and EOFError) Jan van den Broek <balglaas@xs4all.nl> - 2014-07-08 16:38 +0000
              Re: ^D vs ^Z as EOF and DOS dinosaurs talking (was: open() and EOFError) Chris Angelico <rosuav@gmail.com> - 2014-07-09 02:20 +1000
              Re: open() and EOFError Tim Chase <python.list@tim.thechases.com> - 2014-07-08 11:40 -0500
              Re: open() and EOFError Chris Angelico <rosuav@gmail.com> - 2014-07-09 02:50 +1000
          Re: open() and EOFError Steven D'Aprano <steve@pearwood.info> - 2014-07-08 09:03 +0000
            Re: open() and EOFError Chris Angelico <rosuav@gmail.com> - 2014-07-08 20:29 +1000
      Re: open() and EOFError Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-07-07 14:06 +0100
      Re: open() and EOFError Chris Angelico <rosuav@gmail.com> - 2014-07-07 23:27 +1000
      Re: open() and EOFError Chris Angelico <rosuav@gmail.com> - 2014-07-07 23:29 +1000
      Re: open() and EOFError Dan Stromberg <drsalists@gmail.com> - 2014-07-07 09:07 -0700
      Re: open() and EOFError Ian Kelly <ian.g.kelly@gmail.com> - 2014-07-07 11:25 -0600
        Re: open() and EOFError Marko Rauhamaa <marko@pacujo.net> - 2014-07-07 20:31 +0300
          Re: open() and EOFError Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-07-07 18:07 +0000
            Re: open() and EOFError Marko Rauhamaa <marko@pacujo.net> - 2014-07-07 21:42 +0300
            Re: open() and EOFError Roy Smith <roy@panix.com> - 2014-07-07 20:22 -0400
          Re: open() and EOFError Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-07-08 10:09 +1200
            Re: open() and EOFError Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-07-08 00:10 +0100
            Re: open() and EOFError "Neil D. Cerutti" <neilc@norwich.edu> - 2014-07-08 10:29 -0400
      Re: open() and EOFError Chris Angelico <rosuav@gmail.com> - 2014-07-08 03:29 +1000
        Re: open() and EOFError Marko Rauhamaa <marko@pacujo.net> - 2014-07-07 20:40 +0300
          Re: open() and EOFError Chris Angelico <rosuav@gmail.com> - 2014-07-08 10:55 +1000
      Re: open() and EOFError Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-07-07 18:54 -0400

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