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Re: try/except/finally

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On Sun, Jun 8, 2014 at 12:02 PM, Ian Kelly <ian.g.kelly@gmail.com> wrote:
> On Sun, Jun 8, 2014 at 11:57 AM, Joshua Landau <joshua@landau.ws> wrote:
>> On 8 June 2014 08:12, Marko Rauhamaa <marko@pacujo.net> wrote:
>>>
>>> Does anyone have an example motivating a return from finally? It seems
>>> to me it would always be a bad idea as it silently clears all unexpected
>>> exceptions.
>>
>> In a general sense:
>>
>>     try:
>>         something_that_can_break()
>>         return foo() # before clean_up
>>     finally:
>>         clean_up()
>>         if default:
>>             return default() # after clean_up()
>>
>> What's the best replacement? Note: I've never done this.
>
> Why not just move the default out of the finally block?
>
>     try:
>         something_that_can_break()
>         return foo() # before clean_up
>     finally:
>         clean_up()
>     if default:
>         return default() # after clean_up()

Never mind, that doesn't work.  But you could do this:

    try:
        something_that_can_break()
        return foo() # before clean_up
    except ExpectedException:
        if default:
            return default() # after clean_up()
        else:
            raise
    finally:
        clean_up()

And then anything unexpected will be propagated instead of silenced.

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try/except/finally Frank B <fbicknel@gmail.com> - 2014-06-06 10:30 -0700
  Re: try/except/finally Roy Smith <roy@panix.com> - 2014-06-06 13:39 -0400
    Re: try/except/finally Frank B <fbicknel@gmail.com> - 2014-06-06 10:47 -0700
      Re: try/except/finally Ned Batchelder <ned@nedbatchelder.com> - 2014-06-06 14:22 -0400
      Re: try/except/finally Ethan Furman <ethan@stoneleaf.us> - 2014-06-07 15:49 -0700
      Re: try/except/finally Chris Angelico <rosuav@gmail.com> - 2014-06-08 09:47 +1000
        Re: try/except/finally Roy Smith <roy@panix.com> - 2014-06-07 20:12 -0400
          Re: try/except/finally Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-06-08 02:10 +0100
            Re: try/except/finally Roy Smith <roy@panix.com> - 2014-06-07 21:32 -0400
            Re: try/except/finally Marko Rauhamaa <marko@pacujo.net> - 2014-06-08 10:12 +0300
              Re: try/except/finally Joshua Landau <joshua@landau.ws> - 2014-06-08 18:57 +0100
              Re: try/except/finally Ian Kelly <ian.g.kelly@gmail.com> - 2014-06-08 12:07 -0600
              Re: try/except/finally Ian Kelly <ian.g.kelly@gmail.com> - 2014-06-08 12:02 -0600
        Re: try/except/finally Rustom Mody <rustompmody@gmail.com> - 2014-06-07 20:58 -0700
          Re: try/except/finally Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2014-06-10 09:27 +0200
            Re: try/except/finally Marko Rauhamaa <marko@pacujo.net> - 2014-06-10 12:07 +0300
            Re: try/except/finally Rustom Mody <rustompmody@gmail.com> - 2014-06-10 05:06 -0700
              Re: try/except/finally Skip Montanaro <skip@pobox.com> - 2014-06-10 13:11 -0500
                Re: try/except/finally Rustom Mody <rustompmody@gmail.com> - 2014-06-10 19:01 -0700
            Re: try/except/finally Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-06-10 19:14 +0100
              Re: try/except/finally Grant Edwards <invalid@invalid.invalid> - 2014-06-10 18:48 +0000
                Re: try/except/finally Chris Angelico <rosuav@gmail.com> - 2014-06-11 06:37 +1000
                Re: try/except/finally Roy Smith <roy@panix.com> - 2014-06-10 16:38 -0400
                Re: try/except/finally Chris Angelico <rosuav@gmail.com> - 2014-06-11 06:43 +1000
                Re: try/except/finally Ethan Furman <ethan@stoneleaf.us> - 2014-06-10 13:43 -0700
                Re: try/except/finally Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-06-10 22:59 +0100
                Re: try/except/finally Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-06-11 00:00 +0000
                Re: try/except/finally Chris Angelico <rosuav@gmail.com> - 2014-06-11 10:12 +1000
                Re: try/except/finally Roy Smith <roy@panix.com> - 2014-06-10 20:22 -0400
                Re: try/except/finally Tim Delaney <timothy.c.delaney@gmail.com> - 2014-06-11 10:40 +1000
                Re: try/except/finally Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-06-11 01:53 +0100
                Re: try/except/finally Chris Angelico <rosuav@gmail.com> - 2014-06-11 11:00 +1000
                Re: try/except/finally Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-06-11 02:06 +0100
                Re: try/except/finally alister <alister.nospam.ware@ntlworld.com> - 2014-06-11 08:35 +0000
                Re: try/except/finally Roy Smith <roy@panix.com> - 2014-06-11 08:50 -0400
              Re: try/except/finally alister <alister.nospam.ware@ntlworld.com> - 2014-06-10 19:02 +0000
    Re: try/except/finally Joshua Landau <joshua@landau.ws> - 2014-06-08 19:05 +0100
  Re:try/except/finally Dave Angel <davea@davea.name> - 2014-06-07 21:59 -0500
    Re: try/except/finally Philip Shaw <jnufcvyvuc@tznvy.pbz> - 2014-06-09 09:13 +0000
      Re: try/except/finally Marko Rauhamaa <marko@pacujo.net> - 2014-06-09 12:40 +0300
        Re: try/except/finally Shiyao Ma <i@introo.me> - 2014-06-10 00:23 +0800
        Re: try/except/finally Skip Montanaro <skip@pobox.com> - 2014-06-09 11:56 -0500

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