on method

ProEventObserver on(
  1. String event,
  2. void callback(
    1. ProEvent<T> event
    )
)

set a callback for events of this type.

REMEMBER TO DISPOSE INSTANCES OF THIS CLASS OR CANCEL THESE CALLBACKS i.e. call EventEmitter.dispose

Use the special event name of 'all' to fire this callback on all events.

Implementation

ProEventObserver on(String event, void Function(ProEvent<T> event) callback) {
  if (!callbacks.containsKey(event)) callbacks[event] = [];
  callbacks[event]!.add(callback);
  return ProEventObserver(() => callbacks[event]?.remove(callback));
}