Tokens: ERC20 and NFTs

Compatibility considerations for an ERC20 or ERC721 token contract that will work with on-chain governance.

Event signatures

Tally's API listens to event logs from token contracts when indexing them. Your token contract will need to maintain the same event signatures:
event DelegateVotesChanged(
address indexed delegate,
uint previousBalance,
uint newBalance
);
event DelegateChanged(
address indexed delegator,
address indexed fromDelegate,
address indexed toDelegate
);
Your contract will need to support transfer events, too. Tally works with both ERC20 transfer events and ERC721 events.

ERC20:

event Transfer(
address indexed from,
address indexed to,
uint256 amount
);

ERC721:

event Transfer(
address indexed from,
address indexed to,
uint256 indexed tokenId
);

Function signatures

Your token contract also needs to implement voting and delegation functions. If you are using an ERC20 token, you can use the ERC20Votes or the ERC20VotesComp extensions from the OpenZeppelin token contracts library.
If you're using an ERC71 token, you can use OpenZeppelin's draft ERC721Votes extension.
The Tally frontend helps users make these function calls to delegate their votes:
function delegate(address delegatee)
function delegateBySig(
address delegatee,
uint nonce,
uint expiry,
uint8 v,
bytes32 r,
bytes32 s
)
function getVotes(address account) uint256
function name() string
function symbol() string
// ERC20 only:
function decimals() public view returns (uint8)

Name

The token contract must implement the name() function, so that Tally knows what to call the token.
function name() string

Symbol

The token contract must implement a symbol() function, so that Tally knows the short name of the token.
function symbol() string

Decimals

ERC20 token contracts must implement a decimals() function, so that Tally can correctly render token balances:
function decimals() public view returns (uint8)