Safety · medium

25. Custom errors

Cheaper reverts than strings.

Declare `error NotOwner(address caller)` and revert with it in the `onlyOwner` check.

Required in your answer: error NotOwner(address caller)revert NotOwner(msg.sender)

Compiles with solc in your browser

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

contract Owned {
    address public owner = msg.sender;
    // TODO error
    function admin() external view {
        // TODO revert NotOwner if not owner
    }
}

Output appears here.

← 24. Libraries & using for 26. try / catch →