pragma solidity ^0.4.25; contract SimpleStorage { uint value; function delegate(uint _val) public { // store(_val); ← これはエラー // ↓ これはOK require(address(this).call(bytes4(keccak256("store(uint256)")), _val), "call failed"); } function store(uint _val) external { value = _val; } function getMul() public view returns(uint) { return value * 2; } } 0.4.25