EIP712External.sol

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import {EIP712} from "@openzeppelin/contracts/utils/cryptography/EIP712.sol";
import {SignatureChecker} from "@openzeppelin/contracts/utils/cryptography/SignatureChecker.sol";

contract EIP712External is EIP712 {
    constructor(string memory name, string memory version) EIP712(name, version) {}

    function domainSeparator() external view returns (bytes32) {
        return _domainSeparatorV4();
    }

    function isValidSignatureNow(address signer, bytes32 hash, bytes memory signature) external view returns (bool) {
        return SignatureChecker.isValidSignatureNow(signer, hash, signature);
    }

    function getChainId() external view returns (uint256) {
        return block.chainid;
    }
}