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BlockNumberBefore Enforcer

The BlockNumberBeforeEnforcer.sol smart contract adds the ability to caveat before block.numbers.

Deployments​

  • Mainnet: Coming Soon
  • Polygon: Coming Soon
  • Optimism: Coming Soon

How It Works

The terms field is expected to contain the block.number, after which invocations will not be valid. The block.number is passed as a bytes8.

Javascript Example​

const delegation = {
  delegate: '0xd8da6bf26964af9d7eed9e03e53415d37aa96045', // vitalik.eth
  authority:
    '0x0000000000000000000000000000000000000000000000000000000000000000',
  caveats: [
    {
      enforcer: BlockNumberBeforeEnforcer.address,
      // Transaction must be executed before block.number 0x32, which is 10 in decimal format.
      terms: '0x0000000000000032',
    },
  ],
};

Smart Contract​

contract BlockNumberBeforeEnforcer is CaveatEnforcer {
    /**
    * @notice Allows the delegator to specify the latest block the delegation will be valid.
    * @param terms - The block before which the delegation is valid. See test for example.
    * @param transaction - The transaction the delegate might try to perform.
    * @param delegationHash - The hash of the delegation being operated on.
    */
    function enforceCaveat(
        bytes calldata terms,
        Transaction calldata transaction,
        bytes32 delegationHash
    ) public override returns (bool) {
        uint64 blockThreshold = BytesLib.toUint64(terms, 0);
        if (blockThreshold > block.number) {
            return true;
        } else {
            revert("BlockNumberBeforeEnforcer:expired-delegation");
        }
    }
}