An abstract solidity contract that any contract can easily integrate to add a ton of improvements to that contract's user and developer experience for all of its functions:
- Allow users to sign "invocations" instead of transactions, which bring lots of benefits.
- Invocations bring the full user-readability of signTypedData for all of that app's operations.
- Support for MetaTransactions
- Support for batched operations: Many actions in one transaction, and potentially lower gas costs.
- Support for signing multiple actions that aren't blocked by each other, so an urgent transaction isn't blocked by the low nonce of a low-stakes low-gas bid transaction.
- Support for signing commitments that can be lazily submitted to the blockchain later.
- Allow users to sign offchain messages that delegate authority to perform any action they can perform, along with an open-ended system for adding restrictions to that delegation, including revocation.
- Allow the holder of any delegation to issue a delegation from it, also with an off-chain signature and no up-front gas.
- Allows creating invite links to users who don't have accounts set up yet, by signing delegations to a key you send to them.
You can read about the theory behind this library here.
pragma solidity ^0.8.13;
import "./Delegatable.sol";
contract YourContract is Delegatable {
constructor(string memory name) Delegatable(name, "1") {}
function _msgSender () internal view override(Delegatable, Context) returns (address sender) {
if(msg.sender == address(this)) {
bytes memory array = msg.data;
uint256 index = msg.data.length;
assembly {
// Load the 32 bytes word from memory with the address on the lower 20 bytes, and mask those.
sender := and(mload(add(array, index)), 0xffffffffffffffffffffffffffffffffffffffff)
}
} else {
sender = msg.sender;
}
return sender;
}
}
To use this in your own contract, follow these simple steps:
- inherit your contract from contracts/Delegatable.sol.
- Your constructor will need to pass the
Delegatableclass a name for your contract, and a version string, per EIP 712. - Add our sample
_msgSender()method to your contract, as seen in our sample contract. - If you are inheriting from any contracts that use
msg.senderto identify a user, you should now use the_msgSender()method instead, to benefit from this framework. Conveniently, it seems that most OpenZeppelin libraries already use an internal_msgSender()implementation, and so overriding it as shown should be enough to use those libraries.
You can see a working web frontend at MobyMask.
I've started assembling a useful utility for managing memberships & delegations in JS as eth-delegatable-utils (npm, github)
These contracts should be compatible with any signer or wallet that supports signTypedData_v4, like MetaMask.
You will be calling the eth_signTypedData method with the V4 parameter, as seen in the test files.
A fork of Scaffold-ETH boilerplate
Currently most of the good stuff is going on in packages/hardhat.
everything you need to build on Ethereum! 🚀
🧪 Quickly experiment with Solidity using a frontend that adapts to your smart contract:
Prerequisites: Node plus Yarn and Git
clone/fork 🏗 scaffold-eth:
git clone https://github.com/austintgriffith/scaffold-eth.gitinstall and start your 👷 Hardhat chain:
cd scaffold-eth
yarn install
yarn chainin a second terminal window, start your 📱 frontend:
cd scaffold-eth
yarn startin a third terminal window, 🛰 deploy your contract:
cd scaffold-eth
yarn deploy🔏 Edit your smart contract YourContract.sol in packages/hardhat/contracts
📝 Edit your frontend App.jsx in packages/react-app/src
💼 Edit your deployment scripts in packages/hardhat/deploy
📱 Open http://localhost:3000 to see the app
Documentation, tutorials, challenges, and many more resources, visit: docs.scaffoldeth.io
📕 Read the docs: https://docs.soliditylang.org
📚 Go through each topic from solidity by example editing YourContract.sol in 🏗 scaffold-eth
📧 Learn the Solidity globals and units
Check out all the active branches, open issues, and join/fund the 🏰 BuidlGuidl!
Join the telegram support chat 💬 to ask questions and find others building with 🏗 scaffold-eth!
🙏 Please check out our Gitcoin grant too!