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Re: Scope of variable inside list comprehensions?

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Steven D'Aprano wrote:
> On Mon, 05 Dec 2011 19:57:15 +0100, Jean-Michel Pichavant wrote:
>
>   
>> The proper way to propagate information with exceptions is using the
>> exception itself:
>>
>> try:
>>     songs = [Song(_id) for _id in song_ids]
>> except Song.DoesNotExist, exc:
>>     print exc
>>     
>
>
> I'm not entirely sure that this is the proper way to propagate the 
> exception. I see far to many people catching exceptions to print them, or 
> worse, to print a generic, useless message like "an error occurred".
>   
[snip]

You misread me, I was referering to passing *information* with exception 
(in other words, use the exception attributes). In the example I gave, 
the exception has the songId value responsible for raising the error.
I totaly second your opinion on how poor the above handler is (hmm not 
sure about this grammar construct, it sounds like a Yoda sentence).

JM

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Scope of variable inside list comprehensions? Roy Smith <roy@panix.com> - 2011-12-05 09:04 -0800
  Re: Scope of variable inside list comprehensions? Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2011-12-05 20:04 +0200
  Re: Scope of variable inside list comprehensions? Peter Otten <__peter__@web.de> - 2011-12-05 19:10 +0100
  Re: Scope of variable inside list comprehensions? Jean-Michel Pichavant <jeanmichel@sequans.com> - 2011-12-05 19:57 +0100
    Re: Scope of variable inside list comprehensions? Roy Smith <roy@panix.com> - 2011-12-05 11:15 -0800
    Re: Scope of variable inside list comprehensions? Roy Smith <roy@panix.com> - 2011-12-05 11:15 -0800
      Re: Scope of variable inside list comprehensions? Terry Reedy <tjreedy@udel.edu> - 2011-12-05 15:22 -0500
        Re: Scope of variable inside list comprehensions? Roy Smith <roy@panix.com> - 2011-12-05 14:36 -0800
        Re: Scope of variable inside list comprehensions? Roy Smith <roy@panix.com> - 2011-12-05 14:36 -0800
          Re: Scope of variable inside list comprehensions? Terry Reedy <tjreedy@udel.edu> - 2011-12-05 21:23 -0500
    Re: Scope of variable inside list comprehensions? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-05 22:35 +0000
      Re: Scope of variable inside list comprehensions? Roy Smith <roy@panix.com> - 2011-12-05 14:57 -0800
        Re: Scope of variable inside list comprehensions? Chris Angelico <rosuav@gmail.com> - 2011-12-06 13:35 +1100
      Re: Scope of variable inside list comprehensions? Jean-Michel Pichavant <jeanmichel@sequans.com> - 2011-12-06 11:38 +0100
  Re: Scope of variable inside list comprehensions? Rainer Grimm <r.grimm@science-computing.de> - 2011-12-05 22:42 -0800
    Re: Scope of variable inside list comprehensions? 88888 Dihedral <dihedral88888@googlemail.com> - 2011-12-06 02:16 -0800

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