In article <mailman.11587.1404735570.18130.python-l...@python.org>,
Chris Angelico <ros...@gmail.com> wrote:
> On Mon, Jul 7, 2014 at 6:00 PM, Steven D'Aprano <st...@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 :-)
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