WETH10

This twitter hackathon project 🐦 updates the canonical "Wrapped Ether" WETH(9) contract with minor but significant upgrades to save Ethereum network users gas and time in making transactions with tokenized ETH on lo-trust, lo-code 🍬⛽.

Mainnet deployment of commit (34d2712) 🔨. The contract has been deployed at the same address in Kovan, Goerli, Rinkeby and Ropsten.

Total Supply

The supply of WETH10 is capped at type(uint112).max.

Wrapping Ether

Any operation that ends with this contract holding Wrapped Ether is prohibited.

deposit Ether in this contract to receive Wrapped Ether (WETH), which implements the ERC20 standard. WETH is interchangeable with Ether in a 1:1 basis.

withdraw Ether from this contract by unwrapping WETH from your wallet.

The depositTo and withdrawTo convenience functions allow to place the resulting WETH or Ether in an address other than the caller.

The withdrawFrom function allows to unwrap Ether from an owner wallet to a recipient wallet, as long as the owner called approve

Approvals

When an approval is set to type(uint256).max it will not decrease through transferFrom or withdrawFrom calls.

WETH10 implements EIP2612 to set approvals through off-chain signatures

Call Chaining

The depositAndCall and transferAndCall functions allow to deposit Ether or transfer WETH, executing a call in a user-defined contract immediately afterwards, but within the same transaction.

This function will call onTokenTransfer on the recipient address, receiving and passing along a bytes parameter which can be used by the calling contract to process the callback. See EIP667.

Flash Loans

This contract implements EIP3156 that allows to flashLoan an arbitrary amount of Wrapped Ether, unbacked by real Ether, with the condition that it is burned before the end of the transaction. No fees are charged.

This function will call onFlashLoan on the calling address, receiving and passing along a bytes parameter which can be used by the calling contract to process the callback.

Function unrolling

For a minimal gas cost, all functions in WETH10 are external, and a great deal of code repetition exists. To help in understanding the code, blocks that are used recurrently are preceded by a commented-out function call such as // _transferFrom(msg.sender, to, value) that describes the functionality of the block, and followed by a blank line.