vTokens

vTokens are yield-generating tokens that are minted and burned upon deposit and withdraw. The vTokens' value is pegged to the value of the corresponding deposited asset at a 1:1 ratio, and can be safely stored, transferred or traded. All interest collected by the vTokens reserves are distributed to vTokens holders directly by continuously increasing their wallet balance.

The source code can be found on Github here.

For all minting and burning actions, see Deposit() and Withdraw() methods in the LendingPool contract.

EIP20 Methods

All standard EIP20 methods are implemented, such as balanceOf(), transfer(), transferFrom(), approve(), totalSupply(), etc.

balanceOf() will always return the most up to date balance of the user, which includes their principal balance + the interest generated by the principal balance.

EIP2612 Methods

permit()

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

Allows a user to permit another account (or contract) to use their funds using a signed message. This enables gas-less transactions and single approval/transfer transactions.

Parameter	Type	Description
owner	address	The owner of the funds
spender	address	The spender for the funds
value	uint256	The amount the spender is permitted to use
deadline	uint256	The deadline timestamp that the permit is valid. Use type(uint).max for no deadline.
v	uint8	Signature parameter
r	bytes32	Signature parameter
s	bytes32	Signature parameter

_nonces()

function _nonces(address owner) public

Returns the next valid nonce to submit when calling permit()

Methods

UNDERLYING_ASSET_ADDRESS()

function UNDERLYING_ASSET_ADDRESS()

Returns the underlying asset of the vToken.

RESERVE_TREASURY_ADDRESS()

function RESERVE_TREASURY_ADDRESS()

Returns the address of the vTokens reserve treasury.

POOL()

function POOL()

Returns the address of the associated LendingPool for the vToken.

scaledBalanceOf**()**

function scaledBalanceOf(address user)

Returns the scaled balance of user as a uint256.

The scaled balance is the balance of the underlying asset of the user (amount deposited), divided by the current liquidity index at the moment of the update.

I.e. $scaledBalance = amount Deposited / currentLiquidityIndex$

This essentially 'marks' when a user has deposited in the reserve pool, and can be used to calculate the users current compounded vToken balance.

Example:

• User A deposits 1000 DAI at the liquidity index of 1.1

• User B deposits another amount into the same pool

• The liquidity index is now 1.2.

• Therefore to calculate User A's current compounded vToken balance, the reverse operation should be performed: $vTokenBalance = scaledBalance * currentLiquidityIndex$

getScaledUserBalanceAndSupply**()**

function getScaledUserBalanceAndSupply(address user)

Returns the scaled balance of userand the principal total supply.

Return values

Type	Description
uint256	scaled balance of user
uint256	principal total supply

scaledTotalSupply**()**

function scaledTotalSupply()

Returns the scaled total supply of the vToken as uint256.

The scaled total supply is the sum of all the updated stored balances, divided by the reserve index at the moment of the update.

function isTransferAllowed(address user, uint256 amount)

Returns true if a transfer is allowed.