This is a Synth where all the holders can be force-exchanged back to
oUSD at current rates so that the contract can be removed from the system or otherwise repurposed. In order to be liquidated, a Synth must either be frozen (if it is an inverse synth) or have its total outstanding supply worth less than 100\,000 USD. Hence it is mainly useful for eliminating Synths which are unused or at the end of their useful life. The value of the token is read from the system's central ExchangeRates contract.
Purgeable synths were introduced by SIP-3 in response to increasing gas costs associated with minting, and to allow faster reconfiguration of inverse synths.
Purging this Synth is disallowed unless the value of its supply is less than this. Initialised to 100\,000.
The contract address to obtain price information from.
It is necessary to know the current price of this Synth to work out whether it is below the purging threshold.
constructor(address _proxy, TokenState _tokenState, Oikos _oikos, IFeePool _feePool, string _tokenName, string _tokenSymbol, address _owner, bytes32 _currencyKey, ExchangeRates _exchangeRates) public
Allows the owner to liquidate all holders of this token back to
oUSD if the total value of this Synth is worth less than
maxSupplyToPurgeInUSD US dollars at current prices, or if the token is an inverse synth whose price is frozen.
If this is successfully invoked, balances in the provided list of addresses will be deleted, and an equivalent value of oUSD credited to their account.
purge(address addresses) external
- This currency's price must not be stale.
Purged(holder, amountHeld)for each
holder's balance of this currency at the time of liquidation.
Allows the owner to set the address of the exchange rates contract.
- The caller must be the owner of this contract.
Records that a balance of this currency was liquidated back to
oUSD for a particular account.
This event is emitted from the Synth's proxy with the
Purged(address indexed account, uint value)