I am creating a feature where upon switching to any item marked by code to be part of a "kit", the offhand will be replaced by whichever item was equipped when the kit item was last unequipped. Upon doing so in practice, however, the kit item is never saved. Switching to the kit item will clear the offhand, and when unequipped whatever you were holding before will come back as expected. Upon investigation with the debugger, any tag set in the event for the original stack will vanish by the end, but the call chain appears to pass by reference and never copies the itemstack. I could perhaps do it with a capability, but that would necessitate applying the capability to all potential kit items (i.e. everything), causing issues with mods that require items without capabilities in their recipes. I am unsure how to go around this.

Current code,

CombatData.getCap(elb).get(set)TempItemStack

work as expected:

@SubscribeEvent
    public static void kitUp(LivingEquipmentChangeEvent e) {
        if (e.getSlot() == EquipmentSlotType.MAINHAND) {
            ItemStack from = e.getFrom(), to = e.getTo();
            final LivingEntity le = e.getEntityLiving();
            if (GeneralUtils.isKitMain(from)) {
                //interesting, it's being written, then removed immediately.
                e.getFrom().getOrCreateTag().put("kitItem", le.getHeldItemOffhand().write(new CompoundNBT()));
                le.setHeldItem(Hand.OFF_HAND, CombatData.getCap(le).getTempItemStack());
            }
            if (GeneralUtils.isKitMain(to)) {
                CombatData.getCap(le).setTempItemStack(le.getHeldItemOffhand());
                ItemStack replace= ItemStack.read(to.getOrCreateTag().getCompound("kitItem"));
                le.setHeldItem(Hand.OFF_HAND, replace);
            }
        }
    }

 

Uh, anyone? I'm quite confounded.