@:rpc(checked)

[trethaller]

The checked mode is useful when you want to check on the client whether an RPC will succeed before executing it. It generates two additional functions:

• check{Name}(...) : Runs the RPC logic without executing @:do blocks, returning the result
• can{Name}(...) : Like check, but returns a Bool indicating success

Use @:do { } blocks to mark code that should only run when the RPC succeeds:

@:rpc(checked)
function buyItem(itemId:Int) : PurchaseResult {
    var item = inventory.get(itemId);
    if (item == null) return NotFound;
    if (player.gold < item.price) return NotEnoughGold;
    
    @:do {
        // This only executes when called via buyItem(), not checkBuyItem()
        player.gold -= item.price;
        player.addItem(item);
    }
    return Success;
}

// Usage:
if (canBuyItem(itemId)) {
    buyItem(itemId);
}

// Or check the specific result:
var result = checkBuyItem(itemId);
if (result != Success)
    showError(result);

The can{Name} function determines success by:

• If return type is Bool, returns the value directly
• If return type is an enum with @:rpcSuccess(Value), returns result == Value
• Otherwise, returns result != null (result considered an error code)