IERC20Permit
Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in https://eips.ethereum.org/EIPS/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.
Methods
DOMAIN_SEPARATOR
function DOMAIN_SEPARATOR() external view returns (bytes32)
Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
Returns
| Name | Type | Description |
|---|---|---|
| _0 | bytes32 | undefined |
nonces
function nonces(address owner) external view returns (uint256)
Returns the current nonce for owner. This value must be included whenever a signature is generated for {permit}. Every successful call to {permit} increases owner's nonce by one. This prevents a signature from being used multiple times.
Parameters
| Name | Type | Description |
|---|---|---|
| owner | address | undefined |
Returns
| Name | Type | Description |
|---|---|---|
| _0 | uint256 | undefined |
permit
function permit(address owner, address spender, uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s) external nonpayable
Sets value as the allowance of spender over owner's tokens, given owner's signed approval. IMPORTANT: The same issues {IERC20-approve} has related to transaction ordering also apply here. Emits an {Approval} event. Requirements: - spender cannot be the zero address. - deadline must be a timestamp in the future. - v, r and s must be a valid secp256k1 signature from owner over the EIP712-formatted function arguments. - the signature must use owner's current nonce (see {nonces}). For more information on the signature format, see the https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP section].
Parameters
| Name | Type | Description |
|---|---|---|
| owner | address | undefined |
| spender | address | undefined |
| value | uint256 | undefined |
| deadline | uint256 | undefined |
| v | uint8 | undefined |
| r | bytes32 | undefined |
| s | bytes32 | undefined |