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A naive Solidity contract that manages funds for a project
pragma solidity >=0.5.0 <0.6.0;
// 10000000000000000000 // 10 Ethers
contract Project {
// The address who deployed the contract
address private owner;
// The cap to achieved to fund the project
uint public cap;
// The total funded.
uint private total;
// Record of how much each shareholder funded
mapping(address => uint) public funds;
// List of all the shareholder addresses
address payable[] public shareholders;
// On deploy, set a cap and the owner of the contract
constructor(uint _cap) public {
cap = _cap;
owner = msg.sender;
}
/// Add fund to the contract
function addFund() public payable {
// Cap should not have been reached yet
require(total < cap, "Cap already achieved you cannot fund the project anymore");
// Fund should not be 0
require(msg.value != uint(0), "You should provide some funds");
// You should not give more than the cap
require(total + msg.value <= cap, "You cannot give more than the cap");
// If shareholder is not yet register, add it to the list
if (funds[msg.sender] == uint(0)) {
shareholders.push(msg.sender);
}
// Keep record of the fund given by this shareholder
funds[msg.sender] = funds[msg.sender] + msg.value;
// Increment the total given
total = total + msg.value;
}
/// Add an income to be shared amongst the shareholders
function addIncome() public payable {
// Cap should have been reached
require(cap == total, "Cannot add income if the project is not funded");
// Income should not be 0
require(msg.value != uint(0), "You should provide some income");
// Iterate over each shareholder
for (uint i = 0; i < shareholders.length; i++) {
address payable shareholder = shareholders[i];
// IMPORTANT : as there is no double on Ethereum you MUST multiply BEFORE divide
// eg:
// DO 60 * 120 / 100 = 7200 / 100 = 72
// DON'T 60 / 100 * 120 = 0 * 120 = 120
uint share = msg.value * funds[shareholder] / cap;
// Transfer the share on this income to the shareholder
shareholder.transfer(share);
}
}
/// Retrieve the total
function retrieve() public {
// Only the owner can retrieve the total
require(msg.sender == owner);
// The cap should have been reached
require(cap == total, "Cannot retrieve funds if the project is not funded");
// Transfer the funds to the owner
msg.sender.transfer(total);
}
}
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