Option 1:

Receive event information through a delegate

List<Hero> pickedHeroes;
while(pickedHeroes.Count < NumberOfHeroesNeeded) {
	yield return WaitFor.Event("set-hero",
		(player, h) => {
			pickedHeroes.Add(h);
		}
	);
|}

Pro: Doesn't have seemingly "unclean" object-level state; everything stays local to the method.
Con: Having to create a handler method, even if it's anonymous, partially defeats the
 purpose of a co-routine.


Option 2:

Receive event information through object state

List<Hero> pickedHeroes;
while(pickedHeroes.Count < NumberOfHeroesNeeded) {
	yield return WaitFor.Event("set-hero");
	pickedHeroes.Add(this.CurrentEvent.Get<Hero>(0));
}

Pro: No handler method, anonymous or otherwise;
Con: This SEEMS to cause problems with concurrency and/or re-entrancy. In reality, it does
 not; as no game logic is re-entrant or runs concurrently. So, the downside is the perception
 of "unclean" state. Also, this doesn't do the work of deserializing to method parameters
 behind the scenes, so it is not consistent with normal [Handles] marked methods.

Option 3:

Can you think of anything else?