实现一个繁难的拍卖合约
角色剖析:4类角色(拍卖师actioneer,委托人seller,竞买人bidder,买受人buyer)
功能分析:拍卖的根本准则是价高者得,在设定的拍卖时限内,出价最高者最终取得拍卖得标物(提醒:在数据结构上,不必太简单的设计,只需能记录以后最高价的竞买人及其金额、拍卖完结工夫即可。)
- 竞拍性能:竞买人能够屡次出价,价格必须高于以后记录的最高价,并将最高价和竞买人替换。
- 竞拍完结:竞拍完结时,发表胜利者。
状态变量定义和初始化
定义变量:委托人、拍卖师、买受人、竞拍完结标记、工夫限度、竞拍最高金额。(提醒:合约调用者为拍卖师,如果波及到转账的角色须要用address
payable,构造函数能够初始化拍卖师[即msg.sender]、拍卖时限、竞拍完结标记,竞买人在程序中抉择不同account,依据account和msg.value更新买受人和最高金额)
竞拍性能
只有竞拍未完结都能够发动竞拍(提醒:从调用信息窗口抉择买家,输出竞拍价格,用msg.sender和msg.value取得买家和价格信息)
但须要满足以下条件:竞拍未完结;竞拍时的价格肯定要比之前的价格高;竞拍在时限内;
当竞拍被容许时,须要退钱给上一个买家,并替换原有的最高价格和买受人。
完结竞拍
判断是否超过时限,并且是第一次执行本操作,确认通过后,转账给委托人。
合约代码
pragma solidity ^0.8.4;contract auction { uint auctionEndTime; address public auctioneer; address public buyer; address payable public seller; uint public auctionAmount; // Allowed withdrawals of previous bids mapping(address => uint) pendingReturns; // A sign to judge whether the auction is over // Set to true at the end, disallows any change. bool ended; // Events that will be emitted on changes. event auctionAmountIncreased(address bidder, uint amount); event AuctionEnded(address winner, uint amount); // Errors that describe failures. /// The auction has already ended. error AuctionAlreadyEnded(); /// There is already a higher or equal bid. error BidNotHighEnough(uint auctionAmount); /// The auction has not ended yet. error AuctionNotYetEnded(); /// The function auctionEnd has already been called. error AuctionEndAlreadyCalled(); constructor( uint biddingTime, address payable sellerAddress ) { seller = sellerAddress; auctionEndTime = block.timestamp + biddingTime; auctioneer = msg.sender; } /// Bid function function bid() external payable { // Revert the call if the bidding period is over. if (block.timestamp > auctionEndTime) revert AuctionAlreadyEnded(); // Return money if the bid is not high enough if (msg.value <= auctionAmount) revert BidNotHighEnough(auctionAmount); if (auctionAmount != 0) { pendingReturns[buyer] += auctionAmount; } buyer = msg.sender; auctionAmount = msg.value; emit auctionAmountIncreased(msg.sender, msg.value); } /// End the auction and send the highest bid to the seller. function auctionEnd() external payable { // Analyzing conditions if (block.timestamp < auctionEndTime) revert AuctionNotYetEnded(); if (ended) revert AuctionEndAlreadyCalled(); ended = true; emit AuctionEnded(buyer, auctionAmount); // transfer seller.transfer(auctionAmount); }}
首先,依照要求deploy拍卖合约,依照要求设置相干参数,其中seller的地址是 0x78731D3Ca6b7E34aC0F824c42a7cC18A495cabaB
,竞拍的工夫是 120
。
如下所示:
deploy胜利之后,进行初始查问,右下可知,auctioneer即为合约调用者的地址,seller地址与刚刚输出的地址统一。初始buyer地址默认为0,出价金额也为0。
而后进行第一次竞拍,切换至地址结尾为 35cb2
的账户,出价为1949 wei,进行竞拍:
查问后可知,竞拍胜利,并且呈现在以后buyer地位:
而后进行第二次竞拍,切换至地址结尾为 C02db
的账户,出价为6666 wei,进行竞拍:
查问后可知,竞拍胜利,并且呈现在以后buyer地位:
而后进行第三次竞拍,切换至地址结尾为 5E7f2
的账户,出价为9999 wei,进行竞拍:
查问后可知,竞拍胜利,并且呈现在以后buyer地位:
最初,待拍卖工夫完结后进行auctionEnd,依据定义,价高者得,因而winner是出价9999 wei的账户,后果如下: