[Python-ideas] Improving Catching Exceptions

Sven R. Kunze srkunze at mail.de
Thu Jun 22 16:30:57 EDT 2017

Hi folks,

just one note I'd like to dump here.

We usually teach our newbies to catch exceptions as narrowly as 
possible, i.e. MyModel.DoesNotExist instead of a plain Exception. This 
works out quite well for now but the number of examples continue to grow 
where it's not enough.

There are at least three examples I can name off the top of my head:
1) nested StopIteration - PEP 479
2) nested ImportError
3) nested AttributeError

1) is clear. 2) usually can be dealt with by applying the following pattern:

     import user
except ImportError:
     import sys
     if sys.exc_info()[2].tb_next:

Chris showed how to deal with 3). Catching nested exception is not what 
people want many times.

Am I the only one getting the impression that there's a common theme here?


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