Solidity try catch 检测地址类型答案

【问题标题】：Solidity try catch to detect an address typeSolidity try catch 检测地址类型
【发布时间】：2022-11-22 09:59:17
【问题描述】：

我不确定是否理解 try / catch 中的 solidity。下面的代码故意写错了，错误应该被捕获了吧？

function GetTest() external view returns (string memory)  {
        
        address _token_addr = 0x0000000000000000000000000000000000000000;
        console.log("here");
        ERC721 candidateContract = ERC721(_token_addr);
        try candidateContract.supportsInterface(0x80ac58cd) {

              console.log("try");
        }
        catch
        {
              console.log("catch");
        }
        return "";
}

捕获错误并检查地址是否具有预期类型（令牌、地址、合同）的方法是什么？

【问题讨论】：

标签： try-catch blockchain ethereum solidity smartcontracts

【解决方案1】：

try/catch 语句允许您对失败的外部调用做出反应和合同创建电话

当您调用candidateContract.supportsInterface(0x80ac58cd)时，如果此函数恢复，您将捕获错误。例如，如果您部署那些 testCatch 和 ERC165 合约
contract testCatch{
    function GetTest() public view returns (string memory)  {
        // this is the address of deployed ERC165 contract down below
        address _token_addr = 0x406AB5033423Dcb6391Ac9eEEad73294FA82Cfbc;
       
        ERC165 candidateContract = ERC165(_token_addr);
        try candidateContract.supportsInterface(0x80ac58cd) {

             return "tried";
        }
        catch
        {
              return "catch";
        }  
}

}
interface IERC165 {
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}
 
// this contract originally was abstract but I removed it to be able to deploy
contract ERC165 is IERC165 {
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        // this require will fail
        require(2==3,"wrong calculation");
        return interfaceId == type(IERC165).interfaceId;
    }
}
当你调用 GetTest() 函数时，它会因为 require(2==3,"wrong calculation") 行而恢复

但是，如果您从 ERC165 合同中删除了 require 行，
contract ERC165 is IERC165 {
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165).interfaceId;
    }
}
而如果你把这个bytes4“0x80ac58cd”改成错误的bytes4“0x80ac5ccc”，如果你调用这个函数，catch就不会CATCH了。因为 supportsInterface 函数不会还原任何东西。所以 try 块中的代码将运行

【讨论】：