[Ride v5] dApp-to-dApp Invocation Function

⚠️ This is the documentation for the Standard Library version 5, which is currently available for Stagenet only.

Name	Description	Complexity
Invoke	Вызывает вызываемую функцию dApp	TBDL

Invoke

Invokes a dApp callable function.

The Invoke function can be used by a callable function of a dApp script, but not by a verifier function, account script or asset script.

Via the Invoke function, the callable function can invoke a callable function of another dApp, or another callable function of the same dApp, or even itself, and then use the invocation results in subsequent operations. For details, see the dApp-to-dApp Invocation article.

The invocation can contain payments that will be transferred from the balance of the invoking dApp to the balance of the invoked dApp. Payments are forbidden if the dApp invokes itself.

If a payment token is a smart asset, the asset script verifies the Invoke as if it were InvokeScriptTransaction with the following fields:

• dApp, payments, function, args indicated in the Invoke function;
• sender, senderPublicKey of the dApp that performs the invocation;
• id, timestamp, fee, feeAssetId indicated in the original Invoke Script transaction;
• version = 0;

If the asset script denies the action, the Invoke Script transaction is either denied or saved on the blockchain as failed, see the Transaction Validation.

Invoke(dApp: Address|Alias, function: String, arguments: List[Boolean|ByteVector|Int|String|List[Boolean|ByteVector|Int|String]], payments: List[AttachedPayments]): Any

Any means any valid type.

💡 To ensure executing callable functions and applying their actions in the right order, initialize a strict variable by the return value of an Invoke function.

Parameters

Parameter	Description
dApp: Address|Alias	Address or alias of a dApp to invoke
function: String|Unit	Name of a callable function. unit for a default function invocation
arguments: List[Boolean|ByteVector|Int|String|List[Boolean|ByteVector|Int|String]]|Unit	Parameters of a callable function. unit for a default function invocation
payments: List[AttachedPayment]	Payments to transfer from the invoking dApp to the invoked dApp, up to 2

Example

A user sends an Invoke Script transaction that invokes the callable function foo of dApp1.

The foo function invokes the bar function of dApp2 passing the number a and attaching a payment of 1 USDN.

The bar function transfers 1 WAVES to dApp1 and returns the doubled number a.

The foo function writes to dApp1 data storage:

• the value returned by bar,
• the new balance of dApp2 (reduced by 1 WAVES transferred to dApp1).

dApp1:

{-# STDLIB_VERSION 5 #-}
{-# CONTENT_TYPE DAPP #-}
{-# SCRIPT_TYPE ACCOUNT #-}

@Callable(i)
func foo(dapp2: String, a: Integer, key1: String, key2: String) = {
   strict r = Invoke(addressFromStringValue(dapp2),bar,[a],[AttachedPayment(base58'DG2xFkPdDwKUoBkzGAhQtLpSGzfXLiCYPEzeKH2Ad24p',1000000)])
   (
      [
         IntegerEntry(key1, r),
         IntegerEntry(key2, wavesBalance(dapp2).regular)
      ],
      unit
   )
}

dApp2:

{-# STDLIB_VERSION 5 #-}
{-# CONTENT_TYPE DAPP #-}
{-# SCRIPT_TYPE ACCOUNT #-}

@Callable(i)
func bar(a: Int) = {
   let 
   (
      [
         ScriptTransfer(i.caller, 100000000, unit),
      ],
      a*2
   )
}