下面的是核心代码，内部汇编不理解也没事。 你只需要去查下delegatecall和call的区别就明白了 ``` function _delegate(address implementation) internal virtual { assembly { // Copy msg.data. We take full control of memory in this inline assembly // block because it will not return to Solidity code. We overwrite the // Solidity scratch pad at memory position 0. calldatacopy(0, 0, calldatasize()) // Call the implementation. // out and outsize are 0 because we don't know the size yet. let result := delegatecall(gas(), implementation, 0, calldatasize(), 0, 0) // Copy the returned data. returndatacopy(0, 0, returndatasize()) switch result // delegatecall returns 0 on error. case 0 { revert(0, returndatasize()) } default { return(0, returndatasize()) } } } ```