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February 28, 2020 18:14
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Created using remix-ide: Realtime Ethereum Contract Compiler and Runtime. Load this file by pasting this gists URL or ID at https://remix.ethereum.org/#version=soljson-v0.6.1+commit.e6f7d5a4.js&optimize=false&gist=
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pragma solidity >=0.4.22 <0.7.0; | |
/** | |
* @title Storage | |
* @dev Store & retreive value in a variable | |
*/ | |
contract Storage { | |
uint256 number; | |
/** | |
* @dev Store value in variable | |
* @param num value to store | |
*/ | |
function store(uint256 num) public { | |
number = num; | |
} | |
/** | |
* @dev Return value | |
* @return value of 'number' | |
*/ | |
function retreive() public view returns (uint256){ | |
return number; | |
} | |
} |
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pragma solidity >=0.4.22 <0.7.0; | |
/** | |
* @title Owner | |
* @dev Set & change owner | |
*/ | |
contract Owner { | |
address private owner; | |
// event for EVM logging | |
event OwnerSet(address indexed oldOwner, address indexed newOwner); | |
// modifier to check if caller is owner | |
modifier isOwner() { | |
// If the first argument of 'require' evaluates to 'false', execution terminates and all | |
// changes to the state and to Ether balances are reverted. | |
// This used to consume all gas in old EVM versions, but not anymore. | |
// It is often a good idea to use 'require' to check if functions are called correctly. | |
// As a second argument, you can also provide an explanation about what went wrong. | |
require(msg.sender == owner, "Caller is not owner"); | |
_; | |
} | |
/** | |
* @dev Set contract deployer as owner | |
*/ | |
constructor() public { | |
owner = msg.sender; // 'msg.sender' is sender of current call, contract deployer for a constructor | |
emit OwnerSet(address(0), owner); | |
} | |
/** | |
* @dev Change owner | |
* @param newOwner address of new owner | |
*/ | |
function changeOwner(address newOwner) public isOwner { | |
emit OwnerSet(owner, newOwner); | |
owner = newOwner; | |
} | |
/** | |
* @dev Return owner address | |
* @return address of owner | |
*/ | |
function getOwner() external view returns (address) { | |
return owner; | |
} | |
} |
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pragma solidity >=0.4.22 <0.7.0; | |
/// @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; // 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 | |
} | |
// 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 public chairperson; | |
// 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`. | |
constructor(bytes32[] memory proposalNames) public { | |
chairperson = msg.sender; | |
voters[chairperson].weight = 1; | |
// 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`. | |
function giveRightToVote(address voter) public { | |
// If the first argument of `require` evaluates | |
// to `false`, execution terminates and all | |
// changes to the state and to Ether balances | |
// are reverted. | |
// This used to consume all gas in old EVM versions, but | |
// not anymore. | |
// It is often a good idea to use `require` to check if | |
// functions are called correctly. | |
// As a second argument, you can also provide an | |
// explanation about what went wrong. | |
require( | |
msg.sender == chairperson, | |
"Only chairperson can give right to vote." | |
); | |
require( | |
!voters[voter].voted, | |
"The voter already voted." | |
); | |
require(voters[voter].weight == 0); | |
voters[voter].weight = 1; | |
} | |
/// Delegate your vote to the voter `to`. | |
function delegate(address to) public { | |
// assigns reference | |
Voter storage sender = voters[msg.sender]; | |
require(!sender.voted, "You already voted."); | |
require(to != msg.sender, "Self-delegation is disallowed."); | |
// 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)) { | |
to = voters[to].delegate; | |
// We found a loop in the delegation, not allowed. | |
require(to != msg.sender, "Found loop in delegation."); | |
} | |
// Since `sender` is a reference, this | |
// modifies `voters[msg.sender].voted` | |
sender.voted = true; | |
sender.delegate = to; | |
Voter storage delegate_ = voters[to]; | |
if (delegate_.voted) { | |
// If the delegate already voted, | |
// directly add to the number of votes | |
proposals[delegate_.vote].voteCount += sender.weight; | |
} else { | |
// If the delegate did not vote yet, | |
// add to her weight. | |
delegate_.weight += sender.weight; | |
} | |
} | |
/// Give your vote (including votes delegated to you) | |
/// to proposal `proposals[proposal].name`. | |
function vote(uint proposal) public { | |
Voter storage sender = voters[msg.sender]; | |
require(sender.weight != 0, "Has no right to vote"); | |
require(!sender.voted, "Already voted."); | |
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; | |
} | |
/// @dev Computes the winning proposal taking all | |
/// previous votes into account. | |
function winningProposal() public view | |
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() public view | |
returns (bytes32 winnerName_) | |
{ | |
winnerName_ = proposals[winningProposal()].name; | |
} | |
} |
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pragma solidity >=0.4.22 <0.7.0; | |
import "remix_tests.sol"; // this import is automatically injected by Remix. | |
import "./3_Ballot.sol"; | |
contract BallotTest { | |
bytes32[] proposalNames; | |
Ballot ballotToTest; | |
function beforeAll () public { | |
proposalNames.push(bytes32("candidate1")); | |
ballotToTest = new Ballot(proposalNames); | |
} | |
function checkWinningProposal () public { | |
ballotToTest.vote(0); | |
Assert.equal(ballotToTest.winningProposal(), uint(0), "proposal at index 0 should be the winning proposal"); | |
Assert.equal(ballotToTest.winnerName(), bytes32("candidate1"), "candidate1 should be the winner name"); | |
} | |
function checkWinninProposalWithReturnValue () public view returns (bool) { | |
return ballotToTest.winningProposal() == 0; | |
} | |
} |
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// this line is added to create a gist. Empty file is not allowed. |
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