Example usage
Call smart contracts on remote chains
The
callRemote function takes as arguments an array of Call structs. Call.data can be easily encoded with the abi.encodeCall function.struct Call {
// supporting non EVM targets
bytes32 to;
uint256 value;
bytes data;
}
interface IUniswapV3Pool {
function swap(
address recipient,
bool zeroForOne,
int256 amountSpecified,
uint160 sqrtPriceLimitX96,
bytes calldata data
) external returns (int256 amount0, int256 amount1);
}
IUniswapV3Pool pool = IUniswapV3Pool(...);
Call swapCall = Call({
to: TypeCasts.addressToBytes32(address(pool)),
data: abi.encodeCall(pool.swap, (...));
value: 0,
});
Just like all Hyperlane messages that wish to have their messages delivered by a relayer, users must pay for interchain gas.
The various
callRemote functions in the Accounts API each return the message ID as a bytes32. This message ID can then be used by the caller to pay for interchain gas.When specifying the amount of gas, the caller must pay for a gas amount high enough to cover:
- 1."Overhead" gas used by the Accounts API contract and ISM on the destination chain. See the below table to understand what this will be.
- 2.The gas used by the user-specified arbitrary call(s) that will be performed by the interchain account.
For the very first message sent by a sender on the origin chain to a new destination domain, a higher overhead destination gas cost is incurred. This is because the Interchain Account must be created on the destination chain, which involves a new contract being deployed. Subsequent messages to an already-created Interchain Account have a much cheaper overhead.
Interchain Account Already Exists? | Overhead Gas Amount |
|---|---|
No - this is the very first message from a (uint32 origin, address owner) pair to the destination, and a new Interchain Account will be created | 150,000 |
Yes | 30,000 |
function makeCall(uint256 gasAmount, Call[] memory calls) external payable {
// First, send the call
uint32 ethereumDomain = 1;
bytes32 messageId = IInterchainAccountRouter(0xabc..).callRemote(
ethereumDomain,
calls
);
// Then, pay for gas
// The mainnet DefaultIsmInterchainGasPaymaster
IInterchainGasPaymaster igp = IInterchainGasPaymaster(
0x56f52c0A1ddcD557285f7CBc782D3d83096CE1Cc
);
// Pay with the msg.value
igp.payForGas{ value: msg.value }(
// The ID of the message
messageId,
// Destination domain
ethereumDomain,
// The total gas amount. This should be the
// overhead gas amount + gas used by the call being made
gasAmount,
// Refund the msg.sender
msg.sender
);
}
Last modified 1mo ago