Catching all exceptions in Python

• except Exception: vs except BaseException::

  The difference between catching Exception and BaseException is that according to the exception hierarchy exception like SystemExit, KeyboardInterrupt and GeneratorExit will not be caught when using except Exception because they inherit directly from BaseException.

• except: vs except BaseException::

  The difference between this two is mainly in python 2 (AFAIK), and it's only when using an old style class as an Exception to be raised, in this case only expression-less except clause will be able to catch the exception eg.

  class NewStyleException(Exception): passtry:   raise NewStyleExceptionexcept BaseException:   print "Caught"class OldStyleException: passtry:   raise OldStyleExceptionexcept BaseException:   print "BaseException caught when raising OldStyleException"except:   print "Caught"

If you need to catch all exceptions and do the same stuff for all, I'll suggest you this :

try:   #stuffexcept:   # do some stuff

If you don't want to mask "special" python exceptions, use the Exception base class

try:   #stuffexcept Exception:   # do some stuff

for some exceptions related management, catch them explicitly :

try:   #stuffexcept FirstExceptionBaseClassYouWantToCatch as exc:   # do some stuffexcept SecondExceptionBaseClassYouWantToCatch as exc:   # do some other stuff basedexcept (ThirdExceptionBaseClassYouWantToCatch, FourthExceptionBaseClassYouWantToCatch) as exc:   # do some other stuff based

The exception hierarchy from the python docs should be a usefull reading.

In order to avoid masking basic exceptions, you need to "re-raise" any exceptions which aren't the ones which you explicitly want to handle, e.g. (adapted from 8. Errors and Exceptions):

import sys
try:    # do something that could throw an exception:except IOError as (errno, strerror):    print "I/O error({0}): {1}".format(errno, strerror)except ValueError:    print "Could not convert data to an integer."except:    # maybe log the exception (e.g. in debug mode)    # re-raise the exception:    raise