Question

I always have a question about override custom event. I am not sure why or what do to inside override function. I searched google but didn’t get too many feedbacks. I appreciate if someone can light me up. Thanks.

EDIT:

My projects seem work fine even though I use my custom event without override. Anyone could explain it? Thanks.

Answer 1

From the docs:

When creating your own custom Event
class, you must override the inherited
Event.clone() method in order for it
to duplicate the properties of your
custom class. If you do not set all
the properties that you add in your
event subclass, those properties will
not have the correct values when
listeners handle the redispatched
event.

So, you can have a problem if you don’t override clone and redispatch an Event. Also, the problem is not only that the custom properties will not be copied. The clone method will be called on the base class, Event. This will return an Event object, not a CustomEvent. If you have a handler that expects a CustomEvent and receives an Event, an error will be thrown and the code in your handler will not run.