removeListener method

void removeListener (String eventName, EventCallback callback)

Unsubscribe from getting any future events from emitter. This mechanism uses event name and callback to unsubscribe from all possible events.

Implementation

void removeListener(String eventName, EventCallback callback) {
  if (null == eventName || eventName.trim().length == 0) {
    throw ArgumentError.notNull("eventName");
  }

  if (null == callback) {
    throw ArgumentError.notNull("callback");
  }

  // Check if listeners have the specific event already registered.
  // if so, then check for the callback registration.

  if (this._listeners.containsKey(eventName)) {
    List<Listener> subs = this._listeners[eventName];
    subs.removeWhere((element) =>
        element?.eventName == eventName && element?.callback == callback);
  }
}