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Re: try... except with unknown error types

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On 8/21/2011 2:26 PM, Paul Rubin wrote:
> Steven D'Aprano<steve+comp.lang.python@pearwood.info>  writes:
>>> But there's no way to know what that minimum is.  Python libraries throw
>>> all sorts of exceptions that their documentation doesn't mention.
>>
>> Yes, you're absolutely correct. But it's also irrelevant. Most of those
>> exceptions should not be caught, even if you know what they are, because
>> they represent either bugs that should be fixed, or bad data which should
>> raise an exception. A bare except, or except Exception, is hardly ever the
>> right approach.
>
> I'm not sure what to do instead.  The exceptions I'm currently dealing
> with happen when certain network operations go wrong (e.g. network or
> remote host is down, connection fails, etc.)  The remedy in each case is
> to catch the exception, log the error, and try the operation again
> later.  But there's no guaranteed-to-be-complete list in the Python docs
> of all the exceptions that can be thrown.  A new and surprising mode of
> network failure can lead to an unhandled exception, unless you catch
> everything.

I would expect that catching socket.error (or even IOError) should catch 
all of those.

"exception socket.error
A subclass of IOError, this exception is raised for socket-related 
errors. It is recommended that you inspect its errno attribute to 
discriminate between different kinds of errors."

> It's a retail application that would cause some business disruption and
> a pissed off customer if the program went down.  Also it's in an
> embedded box on a customer site.  It's not in Antarctica or anything
> like that, but it's a few towns over, and someone would have to drive
> there (probably through heavy traffic) if something went wrong that
> power cycling the box couldn't fix.


-- 
Terry Jan Reedy

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Thread

try... except with unknown error types Yingjie Lin <Yingjie.Lin@mssm.edu> - 2011-08-19 15:09 -0400
  Re: try... except with unknown error types John Gordon <gordon@panix.com> - 2011-08-19 19:14 +0000
    Re: try... except with unknown error types Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-08-20 06:13 +1000
      Re: try... except with unknown error types John Gordon <gordon@panix.com> - 2011-08-19 20:24 +0000
        Re: try... except with unknown error types Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-08-20 06:45 +1000
          Re: try... except with unknown error types Seebs <usenet-nospam@seebs.net> - 2011-08-20 05:46 +0000
        Re: try... except with unknown error types John Nagle <nagle@animats.com> - 2011-08-20 13:15 -0700
      Re: try... except with unknown error types Paul Rubin <no.email@nospam.invalid> - 2011-08-20 12:18 -0700
        Re: try... except with unknown error types Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-08-21 06:14 +1000
          Re: try... except with unknown error types Paul Rubin <no.email@nospam.invalid> - 2011-08-21 11:26 -0700
            Re: try... except with unknown error types Chris Angelico <rosuav@gmail.com> - 2011-08-21 20:17 +0100
              Re: try... except with unknown error types Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-08-22 10:30 +1000
                Re: try... except with unknown error types Chris Angelico <rosuav@gmail.com> - 2011-08-22 01:41 +0100
                Re: try... except with unknown error types Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-08-22 14:01 +1000
                Re: try... except with unknown error types Paul Rubin <no.email@nospam.invalid> - 2011-08-23 00:21 -0700
                Re: try... except with unknown error types Chris Angelico <rosuav@gmail.com> - 2011-08-23 09:26 +0100
                Re: try... except with unknown error types gene heskett <gheskett@wdtv.com> - 2011-08-23 04:43 -0400
                Re: try... except with unknown error types Paul Rubin <no.email@nospam.invalid> - 2011-08-23 10:43 -0700
                Re: try... except with unknown error types Chris Angelico <rosuav@gmail.com> - 2011-08-23 10:07 +0100
                Re: try... except with unknown error types John Nagle <nagle@animats.com> - 2011-08-31 21:22 -0700
            Re: try... except with unknown error types Ethan Furman <ethan@stoneleaf.us> - 2011-08-21 12:22 -0700
            Re: try... except with unknown error types Terry Reedy <tjreedy@udel.edu> - 2011-08-21 15:52 -0400
              Re: try... except with unknown error types Chris Torek <nospam@torek.net> - 2011-08-31 21:01 +0000
                Re: try... except with unknown error types Stefan Krah <stefan-usenet@bytereef.org> - 2011-09-09 23:41 +0200
                Re: try... except with unknown error types Nobody <nobody@nowhere.com> - 2011-09-10 10:33 +0100
                Re: try... except with unknown error types Peter Otten <__peter__@web.de> - 2011-09-10 12:17 +0200
            Re: try... except with unknown error types Roy Smith <roy@panix.com> - 2011-08-21 17:14 -0400
            Re: try... except with unknown error types Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-08-22 10:25 +1000
              Re: try... except with unknown error types Roy Smith <roy@panix.com> - 2011-08-21 22:09 -0400
            Re: try... except with unknown error types Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-08-23 18:33 +1000

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