通过另一个第三方合同发送ERC721令牌

Question

我已经创建了第三方合同，并且我想使该合同能够代表其他地址进行ERC721令牌转移。 我认为，这样做的唯一方法是将已散列的消息从主地址发送到合同，并允许它完成交易。

有可能实现我的意思吗？

pragma solidity ^0.4.24;


import "../../SuperERC721Token.sol";


contract MyContract {

    SuperERC721Token internal externalToken;

    constructor(address address) public {
        externalToken = SuperERC721Token(address);
    }

    function ThirdPartyTransfer(string hashedTRX) public {
        externalToken.call(hashedTRX); // this function allow the contract to send an ERC721 token to another address
    }
}

Answer 1

假设您要从OtherContract调用SuperERC721Token上的functionA函数，您要做的就是从SuperERC721Token中获取接口，一个ERC20令牌接口的示例是：

interface ERC721 /* is ERC165 */ {
    event Transfer(address indexed _from, address indexed _to, uint256 indexed _tokenId);
    event Approval(address indexed _owner, address indexed _approved, uint256 indexed _tokenId);
    event ApprovalForAll(address indexed _owner, address indexed _operator, bool _approved);
    function balanceOf(address _owner) external view returns (uint256);
    function ownerOf(uint256 _tokenId) external view returns (address);   
    function safeTransferFrom(address _from, address _to, uint256 _tokenId, bytes data) external payable;
    function safeTransferFrom(address _from, address _to, uint256 _tokenId) external payable;
    function transferFrom(address _from, address _to, uint256 _tokenId) external payable;
    function approve(address _approved, uint256 _tokenId) external payable;
    function setApprovalForAll(address _operator, bool _approved) external;
    function getApproved(uint256 _tokenId) external view returns (address);
    function isApprovedForAll(address _owner, address _operator) external view returns (bool);
}

interface ERC165 {
    function supportsInterface(bytes4 interfaceID) external view returns (bool);
}

interface ERC721TokenReceiver {
    function onERC721Received(address _operator, address _from, uint256 _tokenId, bytes _data) external returns(bytes4);
}

在OtherContract上，无论要在哪里调用functionA，都可以放置以下代码：

SuperERC721Token erc721Token= ERC721Token(0x0000000000000000000000000000000000000000); //Replace 0x000000000000000000000000000000000000000 with the address of SuperERC721Token
erc721Token.functionA();

添加您要调用的接口中没有的任何功能。