PonzICO is an impressive piece of engineering.
–Wayne Chain
The great art project of our age is to entirely collapse the distinctions between “fraud” and “performance art,” so that one day mortgage-bond traders will be able to say “wait, no, I wasn’t lying about bond prices to increase my bonus, I was performing a metafictional narrative about bond-price negotiations in order to problematize the underlying foundations of bond trading in late capitalism.”
– Matt Levine
After you invest, vote on the color of my Tesla.
– Josh Cincinnati, PonzICO Founder
Let’s use the live and “real world” blockchain performance art PonzICO investment contract running on the Ethereum world computer.
Read the PonzICO White Paper for how the investment scheme and dividend payouts work and what your money will get used for (hint: thanks for the free Tesla - don’t forget to vote on the color :-) - and maybe a two bedroom condo in San Francisco).
PonzICO is the first ICO to respect your intelligence by calling a spade a spade. Here’s how it differs from your everyday ICO:
- It dispense with tokens entirely - we all want that sweet, sweet ether.
- There is no limited time window for “investment.” Time is an illusion.
- PonzICO also dispenses with the notion that it needs a meaningful product attached to its future earning potential. It is the product.
- All profits from PonzICO are carried in balances linked to prior participants in proportion to their prior investment on a transaction by transaction basis… with a trivial, 50% service fee for yours truly, as nominal recompense for spending a solid couple of days re-learning LaTeX and Solidity.
That’s it. With every new transaction into the PonzICO
investmethod, PonzICO immediately balances that ETH to prior participants based on their current proportion of ownership (minus my extremely minor, entirely fair 50% service fee). Upon updating the balances, the new participant is added to the list to receive future disbursements, and PonzICO dilutes everyone else’s stake accordingly. When they are ready to receive their balance, they simply use thewithdrawmethod. Preexisting holders can always put more ETH into PonzICO to reduce their dilution - especially with the convenientreinvestmethod - at the cost of that transaction being disbursed to current stakeholders.– Josh Cincinnati, PonzICO White Paper
The challenge: Code a contract for the PonzICO investment scheme using sruby :-).
Here’s the code in the JavaScript-like Solidity “world standard” in its full glory:
contract PonzICO {
address public owner;
uint public total;
mapping (address => uint) public invested;
mapping (address => uint) public balances;
address[] investors;
//log event of successful investment/withdraw and address
event Investment(address investor, uint amount);
event Withdrawal(address investor, uint amount);
// constructor for initializing PonzICO.
// the owner is the genius who made this revolutionary smart contract
constructor() public {
owner = msg.sender;
}
// the logic for a small fee for the creator of this contract
// miniscule in the grand scheme of things
function ownerFee(uint amount) private returns (uint fee) {
if (total < 200000 ether) {
fee = amount/2;
balances[owner] += fee;
}
return;
}
// This is where the magic is withdrawn.
// For users with balances. Can only be used to withdraw full balance.
function withdraw()
{
require( balances[msg.sender] > 0 );
uint amount = balances[msg.sender];
balances[msg.sender] = 0;
if (!msg.sender.send(amount)) {
balances[msg.sender] = amount;
} else {
emit Withdrawal(msg.sender, amount);
}
}
// What's better than withdrawing? Re-investing profits!
function reinvest()
{
require( balances[msg.sender] > 0 );
uint dividend = balances[msg.sender];
balances[msg.sender] = 0;
uint fee = ownerFee(dividend);
dividend -= fee;
for (uint i = 0; i < investors.length; i++) {
balances[investors[i]] += dividend * invested[investors[i]] / total;
}
invested[msg.sender] += (dividend + fee);
total += (dividend + fee);
emit Investment(msg.sender, dividend+fee);
}
// This is the where the magic is invested.
// Note the accreditedInvestor() modifier, to ensure only sophisticated
// investors with 0.1 ETH or more can invest. #SelfRegulation
function invest() payable
{
require( msg.value > 100 finney );
// first send the owner's modest 50% fee but only if the total invested is less than 200000 ETH
uint dividend = msg.value;
uint fee = ownerFee(dividend);
dividend -= fee;
// then accrue balances from the generous remainder to everyone else previously invested
for (uint i = 0; i < investors.length; i++) {
balances[investors[i]] += dividend * invested[investors[i]] / total;
}
// finally, add this enterprising new investor to the public balances
if (invested[msg.sender] == 0) {
investors.push(msg.sender);
invested[msg.sender] = msg.value;
} else {
invested[msg.sender] += msg.value;
}
total += msg.value;
emit Investment(msg.sender, msg.value);
}
// finally, fallback function. no one should send money to this contract
// without first being added as an investment.
function () { throw; }
}
(Source: etherscan.io/address/0x1ce7986760ade2bf0f322f5ef39ce0de3bd0c82b/#code)
Can you do better?
Post your code snippets (or questions or comments) on the “official” Ruby Quiz Channel, that is, the ruby-talk mailing list.
Happy hacking and (crypto) blockchain contract scripting with sruby.
Up for a bonus level? Turn the “Vote On My Tesla Color” contract into sruby too :-).
contract VoteOnMyTeslaColor {
address public owner;
enum Color { SolidBlack, MidnightSilverMetallic, DeepBlueMetallic, SilverMetallic, RedMultiCoat }
mapping (uint8 => uint32) public votes;
mapping (address => bool) public voted;
event Votes(Color color, uint num);
event Winner(Color color);
// hardcode production PonzICO address
PonzICO ponzico = PonzICO(0x1ce7986760ADe2BF0F322f5EF39Ce0DE3bd0C82B);
// constructor for initializing VoteOnMyTeslaColor
// the owner is the genius who made the revolutionary smart contract PonzICO
// obviously blue starts with 10 votes because it is objectively the BEST color
constructor() public {
owner = msg.sender;
// YOURE MY BOY BLUE
votes[uint8(2)] = 10;
}
// SUPER ACCREDITED INVESTORS ONLY, YOU CAN ONLY VOTE ONCE
function vote(uint8 color)
{
require( ponzico.invested(msg.sender) >= 0.1 ether && !voted[msg.sender] );
require( color < uint8(5) );
// 0.1 ETH invested in PonzICO per vote, truncated
uint32 num = uint32(ponzico.invested(msg.sender) / (0.1 ether));
votes[color] += num;
voted[msg.sender] = true;
emit Votes(Color(color), num);
}
// pay to vote again! I don't care!
// ...but it'll cost you 1 ether for me to look the other way, wink wink
function itsLikeChicago() payable {
require( voted[msg.sender] && msg.value >= 1 ether );
voted[msg.sender] = false;
}
function winnovate()
{
require( msg.sender == owner );
Color winner = Color.SolidBlack;
for (uint8 choice = 1; choice < 5; choice++) {
if (votes[choice] > votes[choice-1]) {
winner = Color(choice);
}
}
emit Winner(winner);
// keeping dat blockchain bloat on check
selfdestruct(owner);
}
}
(Source: etherscan.io/address/0x75f97d98eb49989f9af40c49a7a1eb32767214f5/#code)