Introduction
ERC20 is a standard which defines a common list of rules that an Ethereum token has to implement, giving developers the ability to program how new tokens will function within the Ethereum ecosystem. ERC20 defines how the tokens are transferred between addresses and how data within each token is accessed.
The ERC777 token standard specifies an improvement of ERC20 while remaining backward compatible. It defines advanced features to interact with tokens. Namely, operators to send tokens on behalf of another address—contract or regular account—and send/receive hooks to offer token holders more control over their tokens.
ERC777 in a nutshell
Transactions – Let's talk about of the most interesting features that this new standard is bringing to the world. ERC777 has a function called send() consists in having a transaction with an amount field and a data bit field. Thus the parameters can be freely selected again by the token user and the token operator in order to forward data to the recipient.
function send(address to, uint256 amount, bytes calldata data) external;
function operatorSend(
address from,
address to,
uint256 amount,
bytes calldata data,
bytes calldata operatorData
) external;
Burning Tokens – ERC777 provides a feature called "Burning tokens". It is the act of destroying existing tokens that explicitly defines two functions to burn tokens (burn and operatorBurn). These functions facilitate the integration of the burning process in wallets and dapps. However, the token contract may prevent some or all holders from burning tokens for any reason. The token contract may also define other functions to burn tokens.
Backward Compatibility – The standard does not use transfer and transferFrom and uses send and operatorSend to avoid confusion and mistakes when deciphering which token standard is being used. Besides, ERC777 allows the implementation of ERC20 functions transfer, transferFrom, approve and allowance alongside to make a token fully compatible with ERC20.
Reference Implementation - getting started
I would suggest two references:
0xjac
This repository contains all reference implementation and all tests. The reference implementation is also available via npm. In order to use it, you can download and setup the npm in your machine, access the npm website to see the instructions.
After the npm configuration, install the erc777 with:
npm install erc777
OpenZeppelin
OpenZeppelin is an open framework of reusable and secure smart contracts in the Solidity. It provides implementations of standards like ERC20, ERC721 and now ERC777 too. The project started providing ERC777 after implementing the issue-1159.
In this contract ERC777.sol, we can see how the ERC777 implementation are being organized. The contract implements the interface IERC777 and IERC20, it is possible to safely interact with ERC22 and ERC777 while all the events are emitted during the interactions.
In order to use the OpenZeppelin implementation in your project, you can download and setup the npm in your machine, access the npm website to see the instructions.
After the npm configuration, install the openzeppelin with:
npm install openzeppelin-solidity
Further details
See ERC777: a New Advanced Token Standard by Jordi Baylina, ERC777's author, along Jacques Dafflon and Thomas Shababi