Writing Exception Classes

Exception classes are not special, you just derive them from Exception:

   1 class HostNotFound(Exception):
   2     def __init__( self, host ):
   3         self.host = host
   4         Exception.__init__(self, 'Host Not Found exception: missing %s' % host)

You may later write:

   1 try:
   2     raise HostNotFound( "taoriver.net" )
   3 except HostNotFound, exc:
   4     # Handle exception.
   5     print exc # -> 'Host Not Found exception: missing taoriver.net'
   6     print exc.host # -> 'taoriver.net'

See Also

HandlingExceptions, TracebackModule

Questions

• How do you relay the traceback information? Relay the traceback information? Moving it higher up the call-stack? Could you try to explain your question?

  • When you're logging exceptions, you want access to the traceback information to. After some research, I believe what you use is extract_tb or extract_stack from the traceback module. -- LionKimbro DateTime(2003-09-07T15:23:43Z)

  Look at cgitb for how to do detailed TB introspection, and as an example of why mixing logic and (HTML) layout is a very bad thing.

• What better exception-foo is out there?

  AlexMartelli's "Dos and Don'ts".