Simple auction

Ethereum was designed with financial applications in mind, that is why auction is equivalent of "Hello World".

There are many existing implementations of an auction, here is one of them: http://solidity.readthedocs.io/en/v0.4.21/solidity-by-example.html#simple-open-auction

• bid just before the end increases the time

Multiple items

Multiple items, with guranteed placements

For example: selling seats at a workshop in an auction and having 5 place guaranteed at certain price.

Scalability issues

For simplicity currenly there is an artificial limit of 2000 accounts participating in the auction.

See test-gasLimit folder for more information about testing gas limits.

Longer term, it is perfectly possible to avoid limitation by providing starting index to each loop. That, however would increase complexity and development time.

We are not selling tickets to Burning Man or The Rolling Stones at Wembley Stadium, 2000 limit is reasonable for now.

premature optimization is the root of all evil

https://en.wikiquote.org/wiki/Donald_Knuth#Computer_Programming_as_an_Art_(1974)

Programmers waste enormous amounts of time thinking about, or worrying about, the speed of noncritical parts of their programs, and these attempts at efficiency actually have a strong negative impact when debugging and maintenance are considered. We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil. Yet we should not pass up our opportunities in that critical 3%.

Front-end Dapp

• Not yet.
• Send ETH directly.
• To refund - send 0 ether transaction.
• To view state of the contract - use Etherscan.

Automatic refund at the end

You don't need to worry about anything, as we witdraw the winning bid, you'll be refunded too.

Theoretically, starting from 1 wei there could be plenty of micro increments and plenty of transfer to excute.

Realistically, even if I pay the gas fees - it won't be that much.

Note the aligned incentives - beneficiary wants to receive ETH therefore chances are the bidders will receive their money.

Tests

• Aiming for 100% coverage.
• truffle test
• TODO: better tooling: https://blog.colony.io/code-coverage-for-solidity-eecfa88668c2

Think (game theory)

• Can buyerA outbid buyerA? Does it make any sense in terms of game theory incentives? Pay extra 25% to extend the auction? It's not me to judge, there could be a valid reason for that.

• With single item auction, outbidding towards the end makes sense to increase time. Does it make sense with multiple items?

Security audits

Please don't hack.

Please don't kill.

Be kind - open an issue, submit a pull request.

Acknowledgements

This is my first contract I wrote from start to finish, not using copy-paste method.

I'm grateful for Kleros and their IICO model that motivated me to level up my coding skills. You can view my commits to their smart contract code here.