Scope of variable inside list comprehensions?

[Jean-Michel Pichavant]

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