GAS 优化
降低 gas 费用的小窍门
优化数据存储
使用紧凑的变量打包(Use Tight Variable Packing)：将较小的数据类型组合到一个单一的存储槽中，以利用 Solidity 的存储打包的优势。 例如，在一个结构体中将 uint8、uint16 或 bool 型组合使用，使它们适应单个 32 字节的存储槽。
最小化状态变量：仅在链上存储必要的数据。 对于较大的数据，考虑使用链下存储解决方案（如 IPFS），并在链上存储其哈希值以保证数据的完整性。
Use bytes32 over string: If possible, use bytes32 for fixed-size strings, as it is more gas-efficient than the dynamically-sized string type.
优化函数执行
使用 view 和 pure 修饰的函数：将不修改状态的函数标记为 view(如果只需要读取状态)或 pure(如果不需要读取状态)，这样在外部调用时可以减少 gas 消耗。
Limit Visibility: Use the most restrictive visibility (private or internal) for functions and variables, as operations are cheaper when they are internal to a contract.
Reuse Computed Values: Store computed values in local variables if they are used multiple times within a function to avoid redundant computation costs.
Efficient Loops and Conditions
Avoid Loops When Possible: Loops can significantly increase gas costs, especially if their iteration count can grow. Consider alternatives like mapping for direct access.
Short-Circuit Evaluation: In if statements and logical expressions, order conditions by likelihood or cost. Solidity 从左到右计算条件，一旦结果确定就会停止计算。
Use Libraries and Delegate Calls
Libraries for Reusable Code: Deploy reusable code as libraries. Libraries can be deployed once and then used by many contracts, reducing the deployment and execution gas costs. 委托调用：使用委托调用实现模块化架构。 这样可以减少合约中的字节码数量，从而降低部署和执行成本。
Efficient Event Logging
Use Events for Data Not Requiring Immediate Retrieval: Instead of storing information that doesn't need to be immediately retrieved in storage variables, emit events. Logs cost significantly less gas than storage.
测试和优化工具
Use Gas Reporting Tools: Tools like Hardhat and Truffle can report gas usage for contract functions. 识别高 gas 函数以进行优化。 Use Remix IDE: It provides detailed gas consumption for transactions and can help identify expensive operations.
可升级的合约
考虑使用代理模式：使用代理可以在不重新部署整个合约的情况下升级逻辑合约，从而节省部署大型合约的 gas。