Mark E. Barrasso (@barrasso), Daniel Beal (@KillerByte)
\nAllows users to wrap any ERC20 token and mint its synthetic counterpart
\nThis SIP proposes to create a new WrapperFactory contract that can deploy new Wrapper contracts to support virtually any ERC20 token. The new Wrapper contract behaves just like its predecessor, the ETH Wrappr from SIP-112.
With respect to adding support for more token wrappers, this SIP proposes a new abstract factory contract that can deploy new wrappers as needed rather than creating another distinct SIP and contract for each new token to be added in the future.
\nA new contract is created, WrapperFactory, which deploys Wrapper instances. Before a new Wrapper instance can be deployed, it must first be approved via SIP. A synthetic token is minted whenever a user deposits a supported ERC20 token into its respective Wrapper. The user can deposit any amount desired however, this is subject to not exceeding the maxTokenAmount, which is configurable via SCCP. There is no duration, interest rate or collateralization ratio, as any user can at any time buy back the ERC20 token available in the contract by burning the synthetic token. SNX stakers benefit as minting and burning are subject to a mintingFeeRate and burningFeeRate, both of which are paid to the fee pool after conversion into sUSD. The WrapperFactory contract supports wrapper deployment for virtually any ERC20 token, and Wrapper automatically handles wrapping/unwrapping of the token for the user.
This SIP makes it easier to deploy Wrapper contracts that can support more assets in the future and will help expand the total supply of synths.
A new Synthetix core contract is created, WrapperFactory, which by means of the factory pattern deploys Wrapper instances using createWrapper. The WrapperFactory assumes functionality previously exposed by EtherWrapper.
Specifically, WrapperFactory contains the following functions:
createWrapper(IERC20 token, bytes32 currencyKey, bytes32 synthContractName)\nowner to create Wrapper contracts. token and currencyKey indicate which token and synth should be wrapped, and synthContractName is included because concatenation of bytes32 strings within solidity is difficult, and should match the AddressResolver name of the contract for currencyKey.isWrapper(address possibleWrapper) returns (bool)\ndistributeFees()\nEtherWrapper.distributeFees, sending fees to the fee pool and informing of statusThe Wrapper created by the factory should be functionally equivalent to SIP-112, with the following exceptions:
\ntoken of source token, and currency key currencyKey of target synthsETHIssued renamed to synthIssuedmaxETH renamed to maxTokenAmountSystemSettings values have additional wrapperAddress argument to match_mint or _burn, equivalent value sUSD is minted into the WrapperFactory contract instead of withholding sETH. This is functionally different in that fees are held as sUSD instead of their matching synth, meaning there is no hedging for the period of time before synth distribution.distributeFees removedEtherWrapper and NativeEtherWrapper are deprecated.
In order to optimize for gas usage and improve gas calculation
\nThe new functions are added:
\nrecordExcludedDebtChange(bytes32 currencyKey, int256 delta) external\nWrapper instances)excludedDebt entry forexcludedIssuedDebts(bytes32[] memory currencyKeys) external view returns (uint256[])\ntakeDebtSnapshot()\nexcludedDebt entries from its total debt calculationExternal functions are added to match settings described in the Configurable Values section below. Of particular note, the mintRate and burnRate\nconfigurabale params will now have the ability to specify a negative value (type will be int256 instead of uint256), effectively incentivising rapid burn or minting of debt if the situation\ncalls for the need. If mintRate is set to -0.5, for example, the user will receive 0.5% more sETH than the ETH they put in. The reverse is true for burnRate--\nthe user will receive 0.5% more ETH when they burn the corresponding amount of sETH.
It is possible that the SystemSettings contract will not fit on L2.
Wrapper initialized with WETH -> sETH
\nGiven that a user has e amount of ETH and ew WETH and the contract has c amount of ETH in spare capacity
ew is larger than or equal to c\ne ETH into the contract\nc ETH is wrapped into WETH and is locked in the contractc(1-mintFeeRate) is minted into the user's wallet in sETHc*mintFeeRate worth of sETH is sent to the fee pool in the form of sUSDu - c worth of ETH is refunded back to the userew WETH into the contract\nc WETH is locked up in the contractc(1-mintFeeRate) is minted into the user's wallet in sETHc*mintFeeRate worth of sETH is sent to the fee pool in the form of sUSDu - c worth of WETH is refunded back to the usermintFeeRate is <0\new WETH into the contract\nc(1-mintFeeRate) WETH is locked up in the contractc is minted into the user's wallet in sETHu is strictly lower than c\ne ETH into the contract\nu ETH is wrapped into WETH and is locked in the contractu(1-mintFeeRate) is minted into the user's wallet in sETHu*mintFeeRate worth of sETH is sent to the fee pool in the form of sUSDew WETH into the contract\nu WETH is locked up in the contractu(1-mintFeeRate) is minted into the user's wallet in sETHmintFeeRate is <0\new WETH into the contract\nu(1-mintFeeRate) WETH is locked up in the contractu is minted into the user's wallet in sETHGiven that the contract's capacity is zero, as maxETH is locked in the contract
Given that a user has u amount of sETH and the contract holds c amount of WETH
u is larger than or equal to c(1+burnFeeRate)\nu sETH and flagging withdrawal in ETH\nc WETH is unwrapped to ETH and is sent to the userc sETH is burnedc * burnFeeRate worth of sETH is swapped to sUSD and sent to the fee poolu - c(1+burnFeeRate) worth of sETH is refunded back to the useru sETH and flagging withdrawal in WETH\nc WETH is sent to the userc sETH is burnedc * burnFeeRate worth of sETH is swapped to sUSD and sent to the fee poolu - c(1+burnFeeRate) worth of sETH is refunded back to the userburnFeeRate is <0\nu sETH and flagging withdrawal in WETH\nc WETH is sent to the userc sETH is burnedu + c(1+burnFeeRate) worth of sETH is refunded back to the useru is strictly lower than c(1+burnFeeRate)\nu sETH and flagging withdrawal in ETH\nu (1-burnFeeRate) worth of WETH is unwrapped to ETH and is sent to the useru * burnFeeRate worth of sETH is swapped to sUSD and sent to the fee poolu (1 - burnFeeRate) sETH is burnedu sETH and flagging withdrawal in WETH\nu (1-burnFeeRate) worth of WETH is sent to the useru * burnFeeRate worth of sETH is swapped to sUSD and sent to the fee poolu (1 - burnFeeRate) sETH is burnedburnFeeRate is <0\nu sETH and flagging withdrawal in WETH\nu (1+burnFeeRate) worth of WETH is sent to the useru 1 sETH is burnedGiven that the contract's holds no WETH
\nGiven that a user attemps to mint with WETH and msg.value is greater than zero then the following takes place:
WETH and ETHThere are 3 new values for each Wrapper created by the WrapperFactory:
\n| Name | \nSetter | \nDescription | \n
|---|---|---|
wrapperMaxTokenAmount | \nsetWrapperMaxTokenAmount | \nMaximum number of tokens in custody of the wrapper | \n
wrapperMintFeeRate | \nsetWrapperMintFeeRate | \nPortion of synths after minting to be withheld for delivery to fee pool. This value may be negative. | \n
wrapperBurnFeeRate | \nsetWrapperBurnFeeRate | \nPortion of synths prior to burning to be withheld for delivery to fee pool. This value may be negative. | \n
For all of the above parameters, the corresponding setter or getter function must be supplied with wrapperAddress to indicate which wrapper should be applied the setting.
In addition, etherWrapperMaxETH, etherWrapperMintFeeRate, and etherWrapperBurnFeeRate are deprecated.
Copyright and related rights waived via CC0.
"}},"pageContext":{"id":"3ff4618c-af10-57a0-b9b1-bb4ccf9c2ee8","frontmatter__sip":182,"__params":{"frontmatter__sip":"182"}}},"staticQueryHashes":[]}