add method
Adds callback
to the list of listeners. If it already exists in the
list, it will not be added again.
Implementation
void add(EventSignalCallback<T> callback) {
if (has(callback)) return;
_listeners.add(callback);
}
Adds callback
to the list of listeners. If it already exists in the
list, it will not be added again.
void add(EventSignalCallback<T> callback) {
if (has(callback)) return;
_listeners.add(callback);
}