[solidity] enum/interface (feat.솔리디티깨부수기)

enum

// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.7.0 <0.9.0;
/*
enum: 사람이 읽을 수 있게, 사용자/개발자에 의해 정의된 상수세트 타임(uint8 = 0~255(2^8-1))
enum 이름 {
    }
    특정한 상태조건을 나타내어 require와 함께 쓴다.
*/

contract lec31 {
    enum CarStatus{
        TurnOff, //0
        TurnOn,  //1
        Driving, //2
        Stop     //3
    }

    CarStatus public carStatus;

    constructor(){
        carStatus = CarStatus.TurnOff; //시동꺼진상태로 일단 시작.
    }

    event carCurrentStatus(CarStatus _carStatus, uint256 _carStatusInInt);

    function turnOnCar() public {
        require(carStatus == CarStatus.TurnOff, "To turn on, your car must be turned off");//require문은 false일때 revert가 작동한다.
        //시동이꺼져있어야 true.  만약 false라면 "To turn ---" require작동!
        //CarStatus.TurnOff 같은뜻 CarStatus(0)
        carStatus = CarStatus(1); //CarStatus.TurnOn 같은뜻 CarStatus(1)
        emit carCurrentStatus(carStatus, uint256(carStatus));
    }

    function DrivingCar() public {
        require(carStatus == CarStatus.TurnOn, "To drive a car, your car must be turned on");
        carStatus = CarStatus.Driving;
        emit carCurrentStatus(carStatus, uint256(carStatus));
    }

    function StopCar() public {
        require(carStatus == CarStatus.Driving, "To drive a car, your car must be turned on");
        carStatus = CarStatus.Stop;
        emit carCurrentStatus(carStatus, uint256(carStatus));
    }

    function turnOffCar() public {
        require(carStatus == CarStatus.TurnOn || carStatus == CarStatus.Stop, "To turn off, your car must be turned on or driving");
        carStatus = CarStatus.TurnOff;
        emit carCurrentStatus(carStatus, uint256(carStatus));
    }

    function CheckStatus() public view returns(CarStatus) {
        return carStatus;
    }

}

 

 

interface

// SPDX-License-Identifier: GPL-3.0
pragma solidity >=0.7.0 <0.9.0;

/*
interface : 스컨 내에서 정의도어야할 필요한 것
    1. 함수는 external로 표시
    2. enum, structs 가능
    3. 변수, 생성자 불가(constructor x)
*/

interface ItemInfo {
    struct item {
        string name;
        uint256 price;
    }
    function addItemInfo(string memory _name, uint256 _price) external; //무조건 external!!
    function getItemInfo(uint256 _index) external view returns(item memory); //무조건 external!!
}

contract lec39 is ItemInfo {
    item[] public itemList; //상속받은 struct를 바로 쓰는 것.
    
    //아래와같이 함수에 파라미터를 맞춰서 써줘야하고 override꼭 붙여야한다!
    function addItemInfo(string memory _name, uint256 _price) override public {
        itemList.push(item(_name, _price)); //item struct 통째로 push
    }
    function getItemInfo(uint256 _index) override public view returns(item memory) {
        return itemList[_index];
    }
}