How do I catch an exception in a decorator but allow the caller to catch it as well?

Question

I have a python function that may raise an exception. The caller catches the exception and deals with it. Now I would like to add a decorator to that function that also<

Answer 1

I just wrote a class similar to what you are doing, but with a little more options available. Here it is:

class ErrorIgnore(object):
   def __init__(self, errors, errorreturn = None, errorcall = None):
      self.errors = errors
      self.errorreturn = errorreturn
      self.errorcall = errorcall

   def __call__(self, function):
      def returnfunction(*args, **kwargs):
         try:
            return function(*args, **kwargs)
         except Exception as E:
            if type(E) not in self.errors:
               raise E
            if self.errorcall is not None:
               self.errorcall(E, *args, **kwargs)
            return self.errorreturn
      return returnfunction

Common usage would be something like:

def errorcall(E, *args):
   print 'exception skipped', E

@ErrorIgnore(errors = [ZeroDivisionError, ValueError], errorreturn = None, errorcall = errorcall)
def myfunction(stuff):
   # do stuff
   # return stuff
   # the errors shown are skipped

Answer 2

Just use raise; (i.e. do not raise anything specific, just raise;) in a catch block to re-raise the exception without "resetting" the traceback.