Stef Mientki a écrit :
<snip>
Alternative (if you *really* want to save the explicit test) is to
attach the behaviour modification to the *relevant* class:
class NonEvent(Event):
def do_nothing(self):
pass
skip = jump = hop = waltz = saunter = do_nothing
def __len__(self):
return 0
NON_EVENT = NonEvent()
del NonEvent
# later:
def amethod(self, event=NON_EVENT):
if event: # still works thanks to __len__ above
event.skip()
# now can avoid test, if desired
event.skip()
thanks guys, the Null, Dummy, Skipper, Nonevent class works great
The NullObject pattern is indeed a proven solution. Another one is to
use a decorator:
def skip_event(event_handler):
def wrapper(self, event=None):
if event is not None:
event.skip()
return event_handler(self, event)
wrapper.__name__ = "skip_event_%s" % event_handler.__name__
wrapper.__doc__ = event_handler.__doc__
return wrapper
@skip_event
def on_menu_file_open(self, event=None):
do_something_usefull_here
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