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Upgradeable, Access-Controlled, and Pausable — Blockchain Smart Contract Design Patterns — Upgradeable, Access-Controlled, and Pausable
Production smart contracts consistently implement a core set of design patterns. Here are the five most important with implementation examples.
// UUPS (Universal Upgradeable Proxy Standard) // The upgrade logic lives in the implementation contract, not the proxy // More gas-efficient than Transparent Proxy import "@openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol"; import "@openzeppelin/contracts-upgradeable/proxy/utils/UUPSUpgradeable.sol"; i...
import "@openzeppelin/contracts/access/AccessControl.sol"; contract ProtocolWithRoles is AccessControl { bytes32 public constant ADMIN_ROLE = keccak256("ADMIN_ROLE"); bytes32 public constant OPERATOR_ROLE = keccak256("OPERATOR_ROLE"); bytes32 public constant GUARDIAN_ROLE = keccak256("GUARDIAN_ROLE"); constructor(addre...
// ALWAYS: check preconditions, update state, THEN make external calls // Prevents reentrancy vulnerabilities function withdraw(uint256 amount) external nonReentrant { // CHECKS require(balances[msg.sender] >= amount, "Insufficient balance"); require(amount > 0, "Cannot withdraw zero"); // EFFECTS (state changes FIRST)...
// Never push payments to many addresses in one transaction // (gas DoS risk if any recipient reverts) // Instead: let recipients pull their own payments mapping(address => uint256) public pendingWithdrawals; function distributeRewards(address[] calldata recipients, uint256[] calldata amounts) external onlyAdmin { // P...
import "@openzeppelin/contracts/utils/Pausable.sol"; contract PausableProtocol is Pausable, AccessControl { bytes32 public constant PAUSER_ROLE = keccak256("PAUSER_ROLE"); // Critical functions respect the pause function deposit(uint256 amount) external whenNotPaused { // Normal deposit logic } function withdraw(uint25...
Common integrations: The Graph, Alchemy/Infura, OpenZeppelin Defender, and popular wallet providers.
Clarify requirements, compliance needs, architecture risks, and launch goals.
Implement core contracts, integrations, product flows, tests, and deployment automation.
Run QA, prepare audit handoff, deploy infrastructure, and support production rollout.
Not necessarily — the choice between immutable and upgradeable involves tradeoffs. Upgradeable contracts allow bug fixes and improvements but introduce the risk that an admin key compromise enables malicious upgrades. Immutable contracts are more trustless (users know the code can never change) but lock in any bugs permanently. Many protocols use upgradeable contracts with a timelock (delay between upgrade proposal and execution) as the middle ground: fixable when needed, but changes are visible in advance for users to exit if they disagree. Some protocols intentionally make contracts immutable after sufficient battle-testing to maximize trustlessness.
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