示例Vyper 中文文档

投票

带委托功能的投票系统：支持投票权委托和最终统计。

投票合约：主席授权参与者投票，支持投票委托，最终统计胜出提案。

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

这个合约实现了一个带委托功能的投票系统：

主席（部署者）授予参与者投票权
每个参与者可以直接投票，或将投票权委托给另一个投票者
委托链会自动传递权重
调用 winningProposal() 返回票数最多的提案

完整合约代码

vyper

#pragma version >0.3.10

# Voting with delegation.

struct Voter:
    weight: int128
    voted: bool
    delegate: address
    vote: int128

struct Proposal:
    name: bytes32
    voteCount: int128

voters: public(HashMap[address, Voter])
proposals: public(HashMap[int128, Proposal])
voterCount: public(int128)
chairperson: public(address)
int128Proposals: public(int128)

@view
@internal
def _delegated(addr: address) -> bool:
    return self.voters[addr].delegate != empty(address)

@view
@external
def delegated(addr: address) -> bool:
    return self._delegated(addr)

@view
@internal
def _directlyVoted(addr: address) -> bool:
    return self.voters[addr].voted and (self.voters[addr].delegate == empty(address))

@view
@external
def directlyVoted(addr: address) -> bool:
    return self._directlyVoted(addr)

@deploy
def __init__(_proposalNames: bytes32[2]):
    self.chairperson = msg.sender
    self.voterCount = 0
    for i: int128 in range(2):
        self.proposals[i] = Proposal(
            name=_proposalNames[i],
            voteCount=0
        )
        self.int128Proposals += 1

@external
def giveRightToVote(voter: address):
    assert msg.sender == self.chairperson
    assert not self.voters[voter].voted
    assert self.voters[voter].weight == 0
    self.voters[voter].weight = 1
    self.voterCount += 1

@internal
def _forwardWeight(delegate_with_weight_to_forward: address):
    assert self._delegated(delegate_with_weight_to_forward)
    assert self.voters[delegate_with_weight_to_forward].weight > 0
    target: address = self.voters[delegate_with_weight_to_forward].delegate
    for i: int128 in range(4):
        if self._delegated(target):
            target = self.voters[target].delegate
            assert target != delegate_with_weight_to_forward
        else:
            break
    weight_to_forward: int128 = self.voters[delegate_with_weight_to_forward].weight
    self.voters[delegate_with_weight_to_forward].weight = 0
    self.voters[target].weight += weight_to_forward
    if self._directlyVoted(target):
        self.proposals[self.voters[target].vote].voteCount += weight_to_forward
        self.voters[target].weight = 0

@external
def forwardWeight(delegate_with_weight_to_forward: address):
    self._forwardWeight(delegate_with_weight_to_forward)

@external
def delegate(to: address):
    assert not self.voters[msg.sender].voted
    assert to != msg.sender
    assert to != empty(address)
    self.voters[msg.sender].voted = True
    self.voters[msg.sender].delegate = to
    self._forwardWeight(msg.sender)

@external
def vote(proposal: int128):
    assert not self.voters[msg.sender].voted
    assert proposal < self.int128Proposals
    self.voters[msg.sender].vote = proposal
    self.voters[msg.sender].voted = True
    self.proposals[proposal].voteCount += self.voters[msg.sender].weight
    self.voters[msg.sender].weight = 0

@view
@internal
def _winningProposal() -> int128:
    winning_vote_count: int128 = 0
    winning_proposal: int128 = 0
    for i: int128 in range(2):
        if self.proposals[i].voteCount > winning_vote_count:
            winning_vote_count = self.proposals[i].voteCount
            winning_proposal = i
    return winning_proposal

@view
@external
def winningProposal() -> int128:
    return self._winningProposal()

@view
@external
def winnerName() -> bytes32:
    return self.proposals[self._winningProposal()].name

代码解析

数据结构

Voter 结构体包含投票权重（weight）、是否已投票（voted）、委托对象（delegate）和投票选择（vote）。Proposal 包含提案名称和累计票数。

权限控制

只有主席（chairperson，即合约部署者）可以调用 giveRightToVote 授予投票权。每个投票者初始权重为 1。

投票委托

delegate() 允许将投票权委托给其他人。_forwardWeight 内部函数处理委托链传递，最多跟踪 4 层委托（防止无限循环）。如果最终目标已直接投票，权重会自动累加到对应提案。

直接投票

vote() 将调用者的权重直接加到指定提案的票数上，并将权重清零以防重复投票。

查询结果

winningProposal() 遍历所有提案返回票数最多的索引，winnerName() 返回获胜提案的名称。

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