Features

1. Listeners support the notion of priority. When two listeners are connected to a same event type, they are called according to their priority. The priority can be changed at any time if necessary. When Listeners have the same priority, the are called in the order of registration. This priority is set to 0 by default, and can be specified by the igs_connect method (last parameter).
2. Listener and Subscriber supports EventFilter and can have more than one
3. Subscribers can:
   1. Inherit from Listener, and override the virtual functions
   2. Use listeners with the add_listener() method with a igs::Function connected to.
4. Source of the event (Publisher) available when:
   1. Receiving an event. The Event class has the appropriate method.
   2. A member function of a Subscriber is called due to an event. The Publisher is, in that case, available only within the function scope.
5. Pluggable EventFilters for:
   1. Listener
   2. Subscriber
6. Block/unblock events from sending/receiving for:
   1. Listener (sending)
   2. Publisher (sending)
   3. Subscriber (receiving)
7. Auto unregistration of:
   1. Subscribers and their associated Listeners when deleted
   2. Listeners when a Publisher is deleted
8. Auto deletion of:
   1. Events after posting
   2. EventFilters when they are not used anymore
   3. Listeners when a Subscriber is deleted
9. Auto listening of methods of type myevent(EVENT*)