let me know the concept of gen_event behaviour

[Miguel Barreiro Paz]

> That is, you define a callback module if you want to handle events that
> are generated. Each event is just a message. Normally, you callback
> module would have a handle_event(Event, State) function that matches on
> a few events and simply ignores the rest.

	When I first read about gen_event I was surprised that your
callback modules couldn't subscribe to certain events and never be annoyed
by events they don't know about. Probably there was a good reason when
gen_event was designed. Anyone?

Regards,

Miguel