合约间交互

合约允许与链上的其他合约进行交互

假设存在链上合约 LuckyNumber

contract LuckyNumber {
  mapping(address => uint) numbers;

  function setNum(uint _num) public {
    numbers[msg.sender] = _num;
  }

  function getNum(address _myAddress) public view returns (uint) {
    return numbers[_myAddress];
  }
}

另一个合约希望访问 LuckyNumber 中的数据，需要先定义其 Interface

interface LuckyNumberInterface {
  function getNum(address _myAddress) public view returns (uint);
}

contract MyContract {
  // LuckyNumber 的合约地址
  address NumberInterfaceAddress = 0xab38...;

  // numberContract 指向一个合约对象
  LuckyNumberInterface numberContract = NumberInterface(NumberInterfaceAddress);

  function someFunction() public {
    // 访问合约方法
    uint num = numberContract.getNum(msg.sender);
  }
}