VariableDebtToken Contract Interface

Implements a variable debt token to track the borrowing positions of users at a variable interest rate.

Transfer and approve functionalities are disabled since debt positions are non-transferable

Although debt tokens are modelled on the ERC20/EIP20 standard, they are non-transferrable. Therefore they do not implement any of the standard ERC20/EIP20 functions relating to transfer() and allowance().

balanceOf

function balanceOf(address user) public view virtual returns (uint256)

mint

function mint(address user, address onBehalfOf, uint256 amount, uint256 index) external virtual returns (bool, uint256)

Mints debt token to the onBehalfOf address

Parameters

Name	Type	Description
user	address	The address receiving the borrowed underlying, being the delegatee in case of credit delegate, or same as onBehalfOf otherwise
onBehalfOf	address	The address receiving the debt tokens
amount	uint256	The amount of debt being minted
index	uint256	The variable debt index of the reserve

Return Values

Name	Type	Description
[0]	bool	True if the previous balance of the user is 0, false otherwise
[1]	uint256	The scaled total debt of the reserve

burn

function burn(address from, uint256 amount, uint256 index) external virtual returns (uint256)

Burns user variable debt

In some instances, a burn transaction will emit a mint event if the amount to burn is less than the interest that the user accrued

Parameters

Name	Type	Description
from	address	The address from which the debt will be burned
amount	uint256	The amount getting burned
index	uint256	The variable debt index of the reserve

Return Values

Name	Type	Description
[0]	uint256	The scaled total debt of the reserve

totalSupply

function totalSupply() public view virtual returns (uint256)

_EIP712BaseId

function _EIP712BaseId() internal view returns (string)

Returns the user readable name of signing domain (e.g. token name)

Return Values

Name	Type	Description
[0]	string	The name of the signing domain

transfer

function transfer(address, uint256) external virtual returns (bool)

Being non transferrable, the debt token does not implement any of the standard ERC20 functions for transfer and allowance.

allowance

function allowance(address, address) external view virtual returns (uint256)

approve

function approve(address, uint256) external virtual returns (bool)

transferFrom

function transferFrom(address, address, uint256) external virtual returns (bool)

increaseAllowance

function increaseAllowance(address, uint256) external virtual returns (bool)

decreaseAllowance

function decreaseAllowance(address, uint256) external virtual returns (bool)

UNDERLYING_ASSET_ADDRESS

function UNDERLYING_ASSET_ADDRESS() external view returns (address)

Returns the address of the underlying asset of this debtToken (E.g. WETH for variableDebtWETH)

Return Values

Name	Type	Description
[0]	address	The address of the underlying asset

approveDelegation

function approveDelegation(address delegatee, uint256 amount) external

Delegates borrowing power to a user on the specific debt token. Delegation will still respect the liquidation constraints (even if delegated, a delegatee cannot force a delegator HF to go below 1)

Parameters

Name	Type	Description
delegatee	address	The address receiving the delegated borrowing power
amount	uint256	The maximum amount being delegated.

delegationWithSig

function delegationWithSig(address delegator, address delegatee, uint256 value, uint256 deadline, uint8 v, bytes32 r, bytes32 s) external

Delegates borrowing power to a user on the specific debt token via ERC712 signature

Parameters

Name	Type	Description
delegator	address	The delegator of the credit
delegatee	address	The delegatee that can use the credit
value	uint256	The amount to be delegated
deadline	uint256	The deadline timestamp, type(uint256).max for max deadline
v	uint8	The V signature param
r	bytes32	The R signature param
s	bytes32	The S signature param

borrowAllowance

function borrowAllowance(address fromUser, address toUser) external view returns (uint256)

Returns the borrow allowance of the user

Parameters

Name	Type	Description
fromUser	address	The user to giving allowance
toUser	address	The user to give allowance to

Return Values

Name	Type	Description
[0]	uint256	The current allowance of toUser

scaledBalanceOf

function scaledBalanceOf(address user) external view returns (uint256)

Returns the scaled balance of the user.

The scaled balance is the sum of all the updated stored balance divided by the reserve's liquidity index at the moment of the update

Parameters

Name	Type	Description
user	address	The user whose balance is calculated

Return Values

Name	Type	Description
[0]	uint256	The scaled balance of the user

getScaledUserBalanceAndSupply

function getScaledUserBalanceAndSupply(address user) external view returns (uint256, uint256)

Returns the scaled balance of the user and the scaled total supply.

Parameters

Name	Type	Description
user	address	The address of the user

Return Values

Name	Type	Description
[0]	uint256	The scaled balance of the user
[1]	uint256	The scaled total supply

scaledTotalSupply

function scaledTotalSupply() public view virtual returns (uint256)

Returns the scaled total supply of the scaled balance token. Represents sum(debt/index)

Return Values

Name	Type	Description
[0]	uint256	The scaled total supply

getPreviousIndex

function getPreviousIndex(address user) external view virtual returns (uint256)

Returns last index interest was accrued to the user's balance

Parameters

Name	Type	Description
user	address	The address of the user

Return Values

Name	Type	Description
[0]	uint256	The last index interest was accrued to the user's balance, expressed in ray