This is a Synth where all the holders can be force-exchanged back to
sUSD 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.
constructor(address payable _proxy, contract TokenState _tokenState, string _tokenName, string _tokenSymbol, address payable _owner, bytes32 _currencyKey, uint256 _totalSupply, address _resolver)
resolverAddressesRequired() view returns (bytes32 addresses)
Allows the owner to liquidate all holders of this token back to
sUSD 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 sUSD credited to their account.
emitPurged(address account, uint256 value)
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.
exchangeRates() view returns (contract IExchangeRates)
Records that a balance of this currency was liquidated back to
sUSD for a particular account.
This event is emitted from the Synth's proxy with the
Purged(address account, uint256 value)