cryptozombies第三讲

zombiehelper.sol

pragma solidity ^0.4.19;

import "./zombiefeeding.sol";

contract ZombieHelper is ZombieFeeding {

//带参数的修饰符的定义
  modifier aboveLevel(uint _level, uint _zombieId) {
    require(zombies[_zombieId].level >= _level);
    _;
  }

  function changeName(uint _zombieId, string _newName) external aboveLevel(2, _zombieId) {
    require(msg.sender == zombieToOwner[_zombieId]);
    zombies[_zombieId].name = _newName;
  }

  function changeDna(uint _zombieId, uint _newDna) external aboveLevel(20, _zombieId) {
    require(msg.sender == zombieToOwner[_zombieId]);
    zombies[_zombieId].dna = _newDna;
  }

  function getZombiesByOwner(address _owner) external view returns(uint[]) {
    uint[] memory result = new uint[](ownerZombieCount[_owner]);
    // 在这里开始
    uint counter = 0;
    for (uint i = 0; i < zombies.length; i++) {
      if (zombieToOwner[i] == _owner) {
        result[counter] = i;
        counter++;
      }
    }
    return result;
  }

}

zombiefeeding.sol

pragma solidity ^0.4.19;

import "./zombiefactory.sol";

contract KittyInterface {
  function getKitty(uint256 _id) external view returns (
    bool isGestating,
    bool isReady,
    uint256 cooldownIndex,
    uint256 nextActionAt,
    uint256 siringWithId,
    uint256 birthTime,
    uint256 matronId,
    uint256 sireId,
    uint256 generation,
    uint256 genes
  );
}

contract ZombieFeeding is ZombieFactory {

  KittyInterface kittyContract;

//onlyOwner修饰符，用来在函数开始时判断是否是所有者
  function setKittyContractAddress(address _address) external onlyOwner {
    kittyContract = KittyInterface(_address);
  }

  function feedAndMultiply(uint _zombieId, uint _targetDna, string species) public {
    require(msg.sender == zombieToOwner[_zombieId]);
    Zombie storage myZombie = zombies[_zombieId];
    _targetDna = _targetDna % dnaModulus;
    uint newDna = (myZombie.dna + _targetDna) / 2;
    if (keccak256(species) == keccak256("kitty")) {
      newDna = newDna - newDna % 100 + 99;
    }
    _createZombie("NoName", newDna);
  }

  function feedOnKitty(uint _zombieId, uint _kittyId) public {
    uint kittyDna;
    (,,,,,,,,,kittyDna) = kittyContract.getKitty(_kittyId);
    feedAndMultiply(_zombieId, kittyDna, "kitty");
  }

}