Recipe: Multi-device pack from scratch

Ingredients

• Two devices: Economy (Provider) and Shop (Consumer).
• Provider variables: coins (int, player, persist on).
• Provider exports: award_coins(amount:int), try_buy(price:int):logic.
• Consumer binding: Economy (links to the Provider).
• UEFN devices: 1 Elimination Manager (for the Provider), 1 Button Device + 1 Item Granter (for the Shop).

Build it

1. 1

   Create the Provider

   Add a new device file Economy. In Game Data → Module, mark it asProvider and add two Exports: award_coins(amount:int):void and try_buy(price:int):logic.
2. 2

   Provider rules: earn

   In Economy, add WHEN On Elimination → DO Give Currency coins +10. Earn rule lives on the Provider because the variable does.
3. 3

   Provider helper: try_buy

   The Composer wires try_buy to a generated helper that checks balance and decrements. You don't hand-write Verse — the export signature drives the codegen.
4. 4

   Create the Consumer

   Add a new device file Shop. In Game Data → Module, mark itConsumer, add a Binding named Economy targeting the Provider, with consumed ports try_buy.
5. 5

   Consumer rules: spend

   In Shop, add WHEN On Button Pressed → DO Call Binding Port (Economy.try_buy, 100), Grant Item shield_potion. The Shop never touches coins directly — it goes through the Provider's API.

Generated Verse

On the Provider, try_buy becomes a public <decides><transacts>method:

economy_device := class(creative_device):
    # ... coins state + helpers ...

    TryBuy<public>(Player:agent, Price:int)<decides><transacts>:void=
        Current := GetCoins[Player]
        Current >= Price
        SetCoins(Player, Current - Price)

On the Consumer, the binding is an @editable field; the call goes through it:

shop_device := class(creative_device):
    @editable Economy:economy_device = economy_device{}
    @editable ShopButton:button_device = button_device{}
    @editable ItemGranter:item_granter_device = item_granter_device{}

    OnBegin<override>()<suspends>:void=
        ShopButton.InteractedWithEvent.Subscribe(OnPress)

    OnPress(Agent:agent):void=
        if (Economy.TryBuy[Agent, 100]):
            ItemGranter.GrantItem(Agent)

UEFN wiring

• Place the economy_device actor anywhere on the map. It has no visible footprint.
• Place the shop_device actor. In the Details panel, the Economy property accepts an economy_device reference — drag the Economy actor in.
• Wire the Consumer's ShopButton and ItemGranter to the corresponding placed devices.

Gotchas