Tech deep dive: Interest Bearing {asset} token

An interest Bearing collateralised, streamable token earning yield via all Strategies involved in the Liquidity Direction Protocol of Alluo.

The Interest Bearing {asset} token is developed and used by Alluo to run deposit farms.

Currently, there are 4 Interest Bearing tokens on Polygon and Ethereum: IbAlluoUSD, IbAlluoEUR, IbAlluoBTC and IbAlluoETH.

How is it interest-bearing?

We have a value growingRatio that increases overtime at the interestPerSecondrate that is set biweekly by the DAO through governance votes. This growingRatio is routinely called by a gelato resolver and updateRatio() is also called before any movement of IbAlluo to ensure that users get the correct values

IbAlluo.sol

/// @notice  Updates the growingRatio
/// @dev If more than the updateTimeLimit has passed, call changeRatio from interestHelper to get correct index
///      Then update the index and set the lastInterestCompound date.

function updateRatio() public whenNotPaused {
    if (block.timestamp >= lastInterestCompound + updateTimeLimit) {
        growingRatio = changeRatio(
            growingRatio,
            interestPerSecond,
            lastInterestCompound
        );
        lastInterestCompound = block.timestamp;
    }
}

An example can be seen below, where if a user wants to transfer exactly $100 USD worth of IbAlluoUSD (keep in mind that 100 IbAlluoUSD is worth 100 * growingRatio > 1 ), the function ensures that the ratio is up to date when transferring $100 worth.

IbAlluo.sol

/**
 * @dev See {IERC20-transfer} but it transfers amount of tokens
 *      which represents asset value
 */
function transferAssetValue(address to, uint256 amount)
    public
    whenNotPaused
    returns (bool)
{
    address owner = _msgSender();
    updateRatio();
    uint256 adjustedAmount = (amount * multiplier) / growingRatio;
    _transfer(owner, to, adjustedAmount);
    emit TransferAssetValue(owner, to, adjustedAmount, amount, growingRatio);
    return true;
}

Key functionality:

The next few subpages will touch upon some key functionalities in the IbAlluo contract, including:

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Last updated 2 years ago

/// @notice Updates the growingRatio /// @dev If more than the updateTimeLimit has passed, call changeRatio from interestHelper to get correct index /// Then update the index and set the lastInterestCompound date. function updateRatio() public whenNotPaused { if (block.timestamp >= lastInterestCompound + updateTimeLimit) { growingRatio = changeRatio( growingRatio, interestPerSecond, lastInterestCompound ); lastInterestCompound = block.timestamp; } }

/** * @dev See {IERC20-transfer} but it transfers amount of tokens * which represents asset value */ function transferAssetValue(address to, uint256 amount) public whenNotPaused returns (bool) { address owner = _msgSender(); updateRatio(); uint256 adjustedAmount = (amount * multiplier) / growingRatio; _transfer(owner, to, adjustedAmount); emit TransferAssetValue(owner, to, adjustedAmount, amount, growingRatio); return true; }