__ERC20Permit_init是什么？

Question

我在查看一些代码时偶然发现了__ERC20Permit_init。这是什么目的？我在谷歌上搜索，并在Initializable.sol of Oppenzeppelin的合同中找到了它。但在不同的合同中使用的是合同中的示例代码。我审查过的代码在一份合同中使用。有什么不同吗？

项目的代码片段

contract LPToken is ILPTokenInit, ILiquidStakingManagerChildContract, Initializable, ERC20PermitUpgradeable {
    //...
    constructor() initializer {}

    function init(
            address _deployer,
            address _transferHookProcessor,
            string calldata _tokenSymbol,
            string calldata _tokenName
         ) external override initializer {
            deployer = _deployer;
            transferHookProcessor = ITransferHookProcessor(_transferHookProcessor);
            __ERC20_init(_tokenName, _tokenSymbol);
            __ERC20Permit_init(_tokenName);
    }
}

Answer 1

我在/contracts/token/ERC20/extensions/ERC20Permit.sol下的ERC20Permit.sol文件中找到了这个

* @dev Implementation of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on `{IERC20-approve}`, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.

因此，它似乎启用了ERC20合同上的一个备用函数，您可以通过签名消息来更改它，而不是发送事务。