> For the complete documentation index, see [llms.txt](https://seer-3.gitbook.io/seer-documentation/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://seer-3.gitbook.io/seer-documentation/developers/contracts/interaction/sdai-on-gnosis/savingsxdai.md).

# SavingsXDai

## Variables

### wxdai

```solidity
contract IWXDAI wxdai
```

### deploymentChainId

```solidity
uint256 deploymentChainId
```

### PERMIT\_TYPEHASH

```solidity
bytes32 PERMIT_TYPEHASH
```

### VERSION

```solidity
string VERSION
```

## Errors

### ERC2612ExpiredSignature

```solidity
error ERC2612ExpiredSignature(uint256 deadline)
```

*Permit deadline has expired.*

### ERC2612InvalidSigner

```solidity
error ERC2612InvalidSigner(address signer, address owner)
```

*Mismatched signature.*

## Functions

### constructor

```solidity
constructor(string _name, string _ticker) public
```

*Set the underlying asset contract. This must be an ERC20-compatible contract (ERC20 or ERC777).*

### receive

```solidity
receive() external payable
```

### \_isValidSignature

```solidity
function _isValidSignature(address signer, bytes32 digest, bytes signature) internal view returns (bool)
```

### permit

```solidity
function permit(address owner, address spender, uint256 value, uint256 deadline, bytes signature) public
```

### permit

```solidity
function permit(address owner, address spender, uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s) external
```

\_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].

CAUTION: See Security Considerations above.\_

### nonces

```solidity
function nonces(address owner) public view virtual returns (uint256)
```

*See {IERC20Permit-nonces}.*

### DOMAIN\_SEPARATOR

```solidity
function DOMAIN_SEPARATOR() external view virtual returns (bytes32)
```

*See {IERC20Permit-DOMAIN\_SEPARATOR}.*