Output variables

Sometimes, the contract you call might transfer funds to a specific address, depending on its execution. The underlying transaction for such a contract call has to have the appropriate number of variable outputs to succeed.

Let's say you deployed a contract with the following method:

    fn transfer(coins: u64, asset_id: AssetId, recipient: Identity) {
        transfer(recipient, asset_id, coins);

When calling transfer_coins_to_output with the SDK, you can specify the number of variable outputs:

        let address = wallet.address();
        let asset_id = contract_id.asset_id(&Bits256::zeroed());

        // withdraw some tokens to wallet
        let response = contract_methods
            .transfer(1_000_000, asset_id, address.into())

with_variable_output_policy sets the policy regarding variable outputs. You can either set the number of variable outputs yourself by providing VariableOutputPolicy::Exactly(n) or let the SDK estimate it for you with VariableOutputPolicy::EstimateMinimum. A variable output indicates that the amount and the owner may vary based on transaction execution.

Note: that the Sway lib-std function mint_to_address calls transfer_to_address under the hood, so you need to call with_variable_output_policy in the Rust SDK tests like you would for transfer_to_address.