Raise an error with a python object

[Luigi Paioro]

Hi!

I have an object put on the bus which has a method that can raise 
errors. How can I handle such situation? I've read that I have to use a 
dbus.Error object, can anybody send me an example?

For example, suppose I have something like this:

#!/usr/bin/python

import gobject
import dbus

import dbus.service

if getattr(dbus, 'version', (0,0,0)) >= (0,41,0):
     import dbus.glib

class HelloWorldObject(dbus.service.Object):
     def __init__(self, bus_name, 
object_path='/org/freedesktop/HelloWorldObject'):
         dbus.service.Object.__init__(self, bus_name, object_path)

     @dbus.service.method('org.freedesktop.HelloWorldIFace')
     def hello(self, flag):
	if not flag:
	    # TODO: RAISE AN ERROR
         return 'Hello from the HelloWorldObject'


session_bus = dbus.SessionBus()
bus_name = dbus.service.BusName('org.freedesktop.HelloWorld', 
bus=session_bus)
object = HelloWorldObject(bus_name)

mainloop = gobject.MainLoop()
mainloop.run()


How can I fix it?

Thanks in advance.

Luigi