Re:Try-except-finally paradox

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From	Dave Angel <davea@davea.name>
Subject	Re:Try-except-finally paradox
Date	Thu, 30 Jan 2014 07:05:15 -0500 (EST)
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 Jessica Ross <deathweasel@gmail.com> Wrote in message:
> I found something like this in a StackOverflow discussion.
>>>> def paradox():
> ...     try:
> ...             raise Exception("Exception raised during try")
> ...     except:
> ...             print "Except after try"
> ...             return True
> ...     finally:
> ...             print "Finally"
> ...             return False
> ...     return None
> ... 
>>>> return_val = paradox()
> Except after try
> Finally
>>>> return_val
> False
> 
> I understand most of this.
> What I don't understand is why this returns False rather than True. Does the finally short-circuit the return in the except block?
> 

The finally has to happen before any return inside the try or the
 except.  And once you're in the finally clause you'll finish it
 before resuming the except clause.  Since it has a return,  that
 will happen before the other returns. The one in the except block
 will never get reached. 

It's the only reasonable behavior., to my mind. 

-- 
DaveA

Thread

Try-except-finally paradox Jessica Ross <deathweasel@gmail.com> - 2014-01-29 21:56 -0800
  Re: Try-except-finally paradox Ian Kelly <ian.g.kelly@gmail.com> - 2014-01-29 23:23 -0700
  Re: Try-except-finally paradox Andrew Berg <robotsondrugs@gmail.com> - 2014-01-30 00:33 -0600
    Re: Try-except-finally paradox Rotwang <sg552@hotmail.co.uk> - 2014-01-30 18:12 +0000
      Re: Try-except-finally paradox Ethan Furman <ethan@stoneleaf.us> - 2014-01-30 10:30 -0800
  Re: Try-except-finally paradox wxjmfauth@gmail.com - 2014-01-29 22:59 -0800
  Re:Try-except-finally paradox Dave Angel <davea@davea.name> - 2014-01-30 07:05 -0500
  Re: Try-except-finally paradox Chris Angelico <rosuav@gmail.com> - 2014-01-31 00:02 +1100
  Re: Try-except-finally paradox MRAB <python@mrabarnett.plus.com> - 2014-01-30 13:11 +0000
  Re: Try-except-finally paradox Chris Angelico <rosuav@gmail.com> - 2014-01-31 00:19 +1100
  Re: Try-except-finally paradox Terry Reedy <tjreedy@udel.edu> - 2014-01-31 00:26 -0500
  Re: Try-except-finally paradox Göktuğ Kayaalp <self@gkayaalp.com> - 2014-02-01 03:58 +0200

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