[Python] Finding an error name

[Martin Kelly]

I'm trying to figure out what error type is given by shelve.open(file, 
"r") when the file does not exist. I've tried everything that looks 
likely, but none of them seem to work. (This is for use in a try: 
except: statement). So for now it's working fine with an except:, but 
that's not optimal... it will catch all errors and it would be better to 
be more specific.

This code snippet:

import shelve
from traceback import format_exc

try:
    db = shelve.open("meh", "r")
except:
    print format_exc()

Gave me this output:
Traceback (most recent call last):
   File "test.py", line 5, in ?
     db = shelve.open("meh", "r")
   File "/usr/lib/python2.4/shelve.py", line 231, in open
     return DbfilenameShelf(filename, flag, protocol, writeback, binary)
   File "/usr/lib/python2.4/shelve.py", line 212, in __init__
     Shelf.__init__(self, anydbm.open(filename, flag), protocol,
writeback, binary)
   File "/usr/lib/python2.4/anydbm.py", line 77, in open
     raise error, "need 'c' or 'n' flag to open new db"
error: need 'c' or 'n' flag to open new db

Exception exceptions.AttributeError: "DbfilenameShelf instance has no
attribute 'writeback'" in  ignored

Does anyone know what the error might be?

Thanks,
Martin