From 93ac2f78e69cfa4215c3d47ac84c2532fabfe2a2 Mon Sep 17 00:00:00 2001 From: chriseth Date: Thu, 9 Mar 2017 12:41:57 +0100 Subject: [PATCH 1/2] Replace example by the one from the documentation. --- contracts/ballot.sol | 143 +++++++++++++++++++++++++++++++++---------- 1 file changed, 111 insertions(+), 32 deletions(-) diff --git a/contracts/ballot.sol b/contracts/ballot.sol index 99219a5d23..7a7d80ef27 100644 --- a/contracts/ballot.sol +++ b/contracts/ballot.sol @@ -1,65 +1,144 @@ pragma solidity ^0.4.0; -contract Ballot { +/// @title Voting with delegation. +contract Ballot { + // This declares a new complex type which will + // be used for variables later. + // It will represent a single voter. struct Voter { - uint weight; - bool voted; - uint8 vote; - address delegate; + uint weight; // weight is accumulated by delegation + bool voted; // if true, that person already voted + address delegate; // person delegated to + uint vote; // index of the voted proposal } - struct Proposal { - uint voteCount; + + // This is a type for a single proposal. + struct Proposal + { + bytes32 name; // short name (up to 32 bytes) + uint voteCount; // number of accumulated votes } - address chairperson; - mapping(address => Voter) voters; - Proposal[] proposals; + address public chairperson; - /// Create a new ballot with $(_numProposals) different proposals. - function Ballot(uint8 _numProposals) { + // This declares a state variable that + // stores a `Voter` struct for each possible address. + mapping(address => Voter) public voters; + + // A dynamically-sized array of `Proposal` structs. + Proposal[] public proposals; + + /// Create a new ballot to choose one of `proposalNames`. + function Ballot(bytes32[] proposalNames) { chairperson = msg.sender; voters[chairperson].weight = 1; - proposals.length = _numProposals; + + // For each of the provided proposal names, + // create a new proposal object and add it + // to the end of the array. + for (uint i = 0; i < proposalNames.length; i++) { + // `Proposal({...})` creates a temporary + // Proposal object and `proposals.push(...)` + // appends it to the end of `proposals`. + proposals.push(Proposal({ + name: proposalNames[i], + voteCount: 0 + })); + } } - /// Give $(voter) the right to vote on this ballot. - /// May only be called by $(chairperson). + // Give `voter` the right to vote on this ballot. + // May only be called by `chairperson`. function giveRightToVote(address voter) { - if (msg.sender != chairperson || voters[voter].voted) return; + if (msg.sender != chairperson || voters[voter].voted) { + // `throw` terminates and reverts all changes to + // the state and to Ether balances. It is often + // a good idea to use this if functions are + // called incorrectly. But watch out, this + // will also consume all provided gas. + throw; + } voters[voter].weight = 1; } - /// Delegate your vote to the voter $(to). + /// Delegate your vote to the voter `to`. function delegate(address to) { - Voter sender = voters[msg.sender]; // assigns reference - if (sender.voted) return; - while (voters[to].delegate != address(0) && voters[to].delegate != msg.sender) + // assigns reference + Voter sender = voters[msg.sender]; + if (sender.voted) + throw; + + // Forward the delegation as long as + // `to` also delegated. + // In general, such loops are very dangerous, + // because if they run too long, they might + // need more gas than is available in a block. + // In this case, the delegation will not be executed, + // but in other situations, such loops might + // cause a contract to get "stuck" completely. + while ( + voters[to].delegate != address(0) && + voters[to].delegate != msg.sender + ) { to = voters[to].delegate; - if (to == msg.sender) return; + } + + // We found a loop in the delegation, not allowed. + if (to == msg.sender) { + throw; + } + + // Since `sender` is a reference, this + // modifies `voters[msg.sender].voted` sender.voted = true; sender.delegate = to; Voter delegate = voters[to]; - if (delegate.voted) + if (delegate.voted) { + // If the delegate already voted, + // directly add to the number of votes proposals[delegate.vote].voteCount += sender.weight; - else + } else { + // If the delegate did not vote yet, + // add to her weight. delegate.weight += sender.weight; + } } - /// Give a single vote to proposal $(proposal). - function vote(uint8 proposal) { + /// Give your vote (including votes delegated to you) + /// to proposal `proposals[proposal].name`. + function vote(uint proposal) { Voter sender = voters[msg.sender]; - if (sender.voted || proposal >= proposals.length) return; + if (sender.voted) + throw; sender.voted = true; sender.vote = proposal; + + // If `proposal` is out of the range of the array, + // this will throw automatically and revert all + // changes. proposals[proposal].voteCount += sender.weight; } - function winningProposal() constant returns (uint8 winningProposal) { - uint256 winningVoteCount = 0; - for (uint8 proposal = 0; proposal < proposals.length; proposal++) - if (proposals[proposal].voteCount > winningVoteCount) { - winningVoteCount = proposals[proposal].voteCount; - winningProposal = proposal; + /// @dev Computes the winning proposal taking all + /// previous votes into account. + function winningProposal() constant + returns (uint winningProposal) + { + uint winningVoteCount = 0; + for (uint p = 0; p < proposals.length; p++) { + if (proposals[p].voteCount > winningVoteCount) { + winningVoteCount = proposals[p].voteCount; + winningProposal = p; } + } + } + + // Calls winningProposal() function to get the index + // of the winner contained in the proposals array and then + // returns the name of the winner + function winnerName() constant + returns (bytes32 winnerName) + { + winnerName = proposals[winningProposal()].name; } } From cd264257eafe65843688275cb81bc3ccae5c4fef Mon Sep 17 00:00:00 2001 From: chriseth Date: Thu, 9 Mar 2017 12:49:40 +0100 Subject: [PATCH 2/2] Escape backticks. --- contracts/ballot.sol | 30 +++++++++++++++--------------- 1 file changed, 15 insertions(+), 15 deletions(-) diff --git a/contracts/ballot.sol b/contracts/ballot.sol index 7a7d80ef27..73d3234bb4 100644 --- a/contracts/ballot.sol +++ b/contracts/ballot.sol @@ -22,13 +22,13 @@ contract Ballot { address public chairperson; // This declares a state variable that - // stores a `Voter` struct for each possible address. + // stores a \`Voter\` struct for each possible address. mapping(address => Voter) public voters; - // A dynamically-sized array of `Proposal` structs. + // A dynamically-sized array of \`Proposal\` structs. Proposal[] public proposals; - /// Create a new ballot to choose one of `proposalNames`. + /// Create a new ballot to choose one of \`proposalNames\`. function Ballot(bytes32[] proposalNames) { chairperson = msg.sender; voters[chairperson].weight = 1; @@ -37,9 +37,9 @@ contract Ballot { // create a new proposal object and add it // to the end of the array. for (uint i = 0; i < proposalNames.length; i++) { - // `Proposal({...})` creates a temporary - // Proposal object and `proposals.push(...)` - // appends it to the end of `proposals`. + // \`Proposal({...})\` creates a temporary + // Proposal object and \`proposals.push(...)\` + // appends it to the end of \`proposals\`. proposals.push(Proposal({ name: proposalNames[i], voteCount: 0 @@ -47,11 +47,11 @@ contract Ballot { } } - // Give `voter` the right to vote on this ballot. - // May only be called by `chairperson`. + // Give \`voter\` the right to vote on this ballot. + // May only be called by \`chairperson\`. function giveRightToVote(address voter) { if (msg.sender != chairperson || voters[voter].voted) { - // `throw` terminates and reverts all changes to + // \`throw\` terminates and reverts all changes to // the state and to Ether balances. It is often // a good idea to use this if functions are // called incorrectly. But watch out, this @@ -61,7 +61,7 @@ contract Ballot { voters[voter].weight = 1; } - /// Delegate your vote to the voter `to`. + /// Delegate your vote to the voter \`to\`. function delegate(address to) { // assigns reference Voter sender = voters[msg.sender]; @@ -69,7 +69,7 @@ contract Ballot { throw; // Forward the delegation as long as - // `to` also delegated. + // \`to\` also delegated. // In general, such loops are very dangerous, // because if they run too long, they might // need more gas than is available in a block. @@ -88,8 +88,8 @@ contract Ballot { throw; } - // Since `sender` is a reference, this - // modifies `voters[msg.sender].voted` + // Since \`sender\` is a reference, this + // modifies \`voters[msg.sender].voted\` sender.voted = true; sender.delegate = to; Voter delegate = voters[to]; @@ -105,7 +105,7 @@ contract Ballot { } /// Give your vote (including votes delegated to you) - /// to proposal `proposals[proposal].name`. + /// to proposal \`proposals[proposal].name\`. function vote(uint proposal) { Voter sender = voters[msg.sender]; if (sender.voted) @@ -113,7 +113,7 @@ contract Ballot { sender.voted = true; sender.vote = proposal; - // If `proposal` is out of the range of the array, + // If \`proposal\` is out of the range of the array, // this will throw automatically and revert all // changes. proposals[proposal].voteCount += sender.weight;