Building an RPG Combat Runtime
6. Target and Activate Abilities
Use activation gates to check cooldowns, mana, and target validity.
Activation starts an ability lifecycle. It does not spend mana or apply effects by itself.
The RPG example uses an activation gate to inspect runtime state:
impl AbilityActivationGate<CombatState, CombatTags, AbilityPayload> for CombatGate {
type Error = CombatError;
type BlockReason = CombatBlockReason;
fn can_activate(&mut self, state: &CombatState, attempt: AbilityActivationAttemptView<'_, CombatTags, AbilityPayload>)
-> Result<AbilityActivationDecision<Self::BlockReason>, Self::Error>
{
if state.mana(attempt.owner_id) < attempt.payload.mana_cost() {
return Ok(AbilityActivationDecision::Block(CombatBlockReason::NotEnoughMana));
}
Ok(AbilityActivationDecision::Allow)
}
}When the gate allows the attempt, Flexweave stores active activation state and emits attempted/started facts. When the gate blocks it, the store does not gain active state and the runtime receives attempted/rejected facts.