No import exceptions needed in Python 2.x
>>> try:
... a > 0
... except NameError as e:
... print e.message.split("'")[1]
...
a
>>>
You assign the reference for 'a' as such:
>>> try:
... a > 0
... except NameError as e:
... locals()[e.message.split("'")[1]] = 0
...
>>> a
0