Project_DappZombiesFactory.sol/lesson-03chapter-02ownable.sol at master · contract1/Project_DappZombiesFactory.sol · GitHub

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pragma solidity ^0.4.25;

contract Ownable {
  address private _owner;

  event OwnershipTransferred(
    address indexed previousOwner,
    address indexed newOwner
  );


  constructor() internal {
    _owner = msg.sender;
    emit OwnershipTransferred(address(0), _owner);
  }


  function owner() public view returns(address) {
    return _owner;
  }


  modifier onlyOwner() {
    require(isOwner());
    _;
  }


  function isOwner() public view returns(bool) {
    return msg.sender == _owner;
  }


  function renounceOwnership() public onlyOwner {
    emit OwnershipTransferred(_owner, address(0));
    _owner = address(0);
  }


  function transferOwnership(address newOwner) public onlyOwner {
    _transferOwnership(newOwner);
  }


  function _transferOwnership(address newOwner) internal {
    require(newOwner != address(0));
    emit OwnershipTransferred(_owner, newOwner);
    _owner = newOwner;
  }
}