This is a simple list of admin-controlled addresses, forming an
(address -> uint256 metadata)
on-chain mapping data type.
npm i address-list --save
// MyContract.sol
contract MyContract {
IAddressList public immutable list;
constructor() public {
// Use latest factory contract address from ./deploy/*/contracts.json
IAddressListFactory addressFactory =
IAddressListFactory(0xD57b41649f822C51a73C44Ba0B3da4A880aF0029);
list = IAddressList(addressFactory.createList());
}
}
The primary uses include governance, on-chain security, creating on-chain filtering lists, or creating contract<->contract proxy routes. A key motivation was mirroring the off-chain Token Lists with similar on-chain infrastructure.
Anybody may create and administer their own token list ("AddressList"), using a provided factory contract.
Beyond the usual whitelist filtering, on-chain token lists can be used to publish personal token lists, a list of all tokens in the Compound, Synthetix or Yearn universe, and more.
- Fast
- O(1) queries, addition and removal
- Admin-specified metadata value associated with each address. uint256. Cannot be zero.
- Role-based access control (RBAC), to separate list admin duties from list owner.
As described in the summary, an AddressList is an on-chain (address,uint256) mapping utility.
In the simple case, the metadata value is set to one (1), to indicate presence in the set of addresses.
In more complex examples, this can be used in forwarding and proxy scenarios as an on-chain (address,address) mapping, or even an on-chain (uint256,address) mapping if you don't mind a few ugly casts.
The only requirements are that both key (address) and value (uint256) must be non-zero.
One use case for AddressList is as a administered list, for an otherwise decentralized system. For example, a permissionless asset management system, with no owner, that relies on a administered token whitelist provided by AddressList. The gateway into this example system is provided by an administrative multi-sig or DAO managing a list of token addresses.
Token lists are administered by a list administrator, so delegated
to the LIST_ADMIN role. This is initially the contract owner - the
Ethereum account that called the factory contract.
See the OpenZeppelin RBAC documentation for further information about administering roles.