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公司股票

模拟股票发行、买卖、转让和公司付款的简化金融系统。

公司股票合约：模拟股票发行、买卖、转让和公司付款的简化金融系统。

学习用途

本示例仅用于学习目的。请勿在未经充分审查和测试的情况下用于生产环境。

概览

这个合约模拟了一个简化的公司股票系统：

  • 公司初始持有所有股票
  • 用户可以用 ETH 按固定价格购买股票
  • 股东可以回售股票换回 ETH
  • 股东之间可以直接转让股票
  • 公司可以用合约余额支付账单

完整合约代码

vyper

#pragma version >0.3.10

event Transfer:
    sender: indexed(address)
    receiver: indexed(address)
    value: uint256

event Buy:
    buyer: indexed(address)
    buy_order: uint256

event Sell:
    seller: indexed(address)
    sell_order: uint256

event Pay:
    vendor: indexed(address)
    amount: uint256

company: public(address)
totalShares: public(uint256)
price: public(uint256)

holdings: HashMap[address, uint256]

@deploy
def __init__(_company: address, _total_shares: uint256, initial_price: uint256):
    assert _total_shares > 0
    assert initial_price > 0
    self.company = _company
    self.totalShares = _total_shares
    self.price = initial_price
    self.holdings[self.company] = _total_shares

@view
@external
def stockAvailable() -> uint256:
    return self._stockAvailable()

@external
@payable
def buyStock():
    buy_order: uint256 = msg.value // self.price
    assert self._stockAvailable() >= buy_order
    self.holdings[self.company] -= buy_order
    self.holdings[msg.sender] += buy_order
    log Buy(buyer=msg.sender, buy_order=buy_order)

@view
@external
def getHolding(_stockholder: address) -> uint256:
    return self._getHolding(_stockholder)

@view
@external
def cash() -> uint256:
    return self.balance

@external
def sellStock(sell_order: uint256):
    assert sell_order > 0
    assert self._getHolding(msg.sender) >= sell_order
    assert self.balance >= (sell_order * self.price)
    self.holdings[msg.sender] -= sell_order
    self.holdings[self.company] += sell_order
    send(msg.sender, sell_order * self.price)
    log Sell(seller=msg.sender, sell_order=sell_order)

@external
def transferStock(receiver: address, transfer_order: uint256):
    assert transfer_order > 0
    assert self._getHolding(msg.sender) >= transfer_order
    self.holdings[msg.sender] -= transfer_order
    self.holdings[receiver] += transfer_order
    log Transfer(sender=msg.sender, receiver=receiver, value=transfer_order)

@external
def payBill(vendor: address, amount: uint256):
    assert msg.sender == self.company
    assert self.balance >= amount
    send(vendor, amount)
    log Pay(vendor=vendor, amount=amount)

@view
@external
def debt() -> uint256:
    return self._debt()

@view
@external
def worth() -> uint256:
    return self.balance - self._debt()

@view
@internal
def _debt() -> uint256:
    return (self.totalShares - self._stockAvailable()) * self.price

@view
@internal
def _stockAvailable() -> uint256:
    return self.holdings[self.company]

@view
@internal
def _getHolding(_stockholder: address) -> uint256:
    return self.holdings[_stockholder]

代码解析

事件系统

合约定义了四个事件（Transfer、Buy、Sell、Pay）用于链下监听交易活动。

买卖机制

buyStock 接收 ETH 按固定价格换算为股票数量（向下取整）。sellStock 反向操作，检查公司有足够 ETH 后回购股票。

公司财务

debt() 计算公司因售出股票产生的负债（已售股数 x 价格），worth() 返回净值（余额 - 负债）。payBill 仅允许公司地址调用。

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