Slot Change Hooks

When an auto-generated slot setter runs (e.g. setName("Thorin")), it checks for optional convention-based hook methods on the owning object before and after mutating internal state:

(class Character extends SvStorableNode {

    initPrototypeSlots () {
        {
            const slot = this.newSlot("level", 1);
            slot.setSlotType("Number");
            slot.setSyncsToView(true);
        }
    }

    // Optional hook called BEFORE value is mutated
    willUpdateSlotLevel (oldValue, newValue) {
        console.log("Level changing from", oldValue, "to", newValue);
    }

    // Optional hook called AFTER value is mutated
    didUpdateSlotLevel (oldValue, newValue) {
        this.recalculateHitPoints();
    }

}.initThisClass());

1. Setter Invoked: setName(newValue)
2. willUpdateSlotName(oldVal, newVal): Called if defined on the object.
3. Value Assignment: Internal private variable _name is updated.
4. didUpdateSlotName(oldVal, newVal): Called if defined on the object.
5. Mutation Notification: If setSyncsToView(true) is set, posts "didChangeSlot" notification via SvNotificationCenter.

• Slots: Complete guide to slot metadata and declarations.
• Notification Center: Weak observer event dispatch.