"Martin v. Loewis" wrote:
http://python.org/sf/518846 reports that new-style classes cannot be used as exceptions. I think it is desirable that this is fixed, but I also believe that it conflicts with string exceptions. So I would like to propose that string exceptions are deprecated for Python 2.3, in order to remove them in Python 2.4, simultaneously allowing arbitrary objects as exceptions.
Should it be arbitrary objects or just subclasses of exception: "It is recommended that user-defined exceptions in new code be derived from Exception, although for backward compatibility reasons, this is not required. Eventually this rule will be tightened."