erc223
v0.0.2
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Dexaran/ERC223-token-standard : [Github Repo](https://github.com/Dexaran/ERC223-token-standard) ### EIP 223
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This Repo is has used work from the following repos:
Dexaran/ERC223-token-standard : Github Repo
EIP 223
Read the original discussion and formal description here: https://github.com/ethereum/eips/issues/223
Current implementation
Main ERC223 contracts:
- IERC223.sol: Token interface. The minimal common API ERC223 tokens and receivers must implement in order to interact with each other.
- ERC223.sol: Token contract. Defines logic of the basic ERC223 token. This functionality can be extended with additional functions (such as
burn()
,mint()
, ownership orapprove / transferFrom
pattern of ERC20). - Recipient interface: A dummy receiver that is intended to accept ERC223 tokens. Use
contract MyContract is IERC223Recipient
to make contract capable of accepting ERC223 token transactions. Contract that does not support IERC223Recipient interface can receive tokens if this contract implements a permissive fallback function (this method of token receiving is not recommended). If a contract does not implement IERC223RecipienttokenReceived
function and does not implement a permissive fallback function then this contract can not receive ERC223 tokens.
Extensions of the base functionality
ERC223Mintable.sol: Minting functinality for ERC223 tokens. Use
contract MyToken is ERC223Mintable
to make your token mintable. The address you used to deploy this contract will receive Minter functinality and will be allowed to assign new minters and increase the totalSupply of the token.ERC223Burnable.sol: Burning functionality implementation for ERC223 tokens. Use
contract MyToken is ERC223Burnable
to make your token burnable. Allows any address to burn its tokens by calling theburn
function of the contract. There is no possibility to burn someone else's tokens in this implementation.
ERC223 token standard.
ERC20 token standard suffers critical problems, that caused loss of approximately $3,000,000 at the moment (31 Dec, 2017). The main and the most important problem is the lack of event handling mechanism in ERC20 standard.
ERC223 is a superset of the ERC20. It is a step forward towards economic abstraction at the application/contract level allowing the use of tokens as first class value transfer assets in smart contract development. It is also a more secure standard as it doesn't allow token transfers to contracts that do not explicitly support token receiving.
contract ERC223 {
function transfer(address to, uint value, bytes data) {
uint codeLength;
assembly {
codeLength := extcodesize(_to)
}
balances[msg.sender] = balances[msg.sender].sub(_value);
balances[_to] = balances[_to].add(_value);
if(codeLength>0) {
// Require proper transaction handling.
ERC223Receiver receiver = ERC223Receiver(_to);
receiver.tokenReceived(msg.sender, _value, _data);
}
}
}
The main problems of ERC20 that ERC223 solves
- Lost tokens: there are two different ways to transfer ERC20 tokens depending on is the receiver address a contract or a wallet address. You should call
transfer
to send tokens to a wallet address or callapprove
on token contract thentransferFrom
on receiver contract to send tokens to contract. Accidentally call oftransfer
function to a contract address will cause a loss of tokens inside receiver contract. - Impossibility of handling incoming token transactions / lack of event handling in ERC20: ERC20 token transaction is a call of
transfer
function inside token contract. ERC20 token contract is not notifying receiver that transaction occurs. Also there is no way to handle incoming token transactions on contract and no way to reject any non-supported tokens. - Optimization of ERC20 address-to-contract communication: You should call
approve
on token contract and then calltransferFrom
on another contract when you want to deposit your tokens into it. In fact address-to-contract transfer is a couple of two different transactions in ERC20. It also costs twice more gas compared to ERC223 transfers. In ERC223 address-to-contract transfer is a single transaction just like address-to-address transfer. - Ether transactions and token transactions behave differently: one of the goals of developing ERC223 was to make token transactions similar to Ether transactions to avoid users mistakes when transferring tokens and make interaction with token transactions easier for contract developers.
ERC223 advantages.
- Provides a possibility to avoid accidentally lost tokens inside contracts that are not designed to work with sent tokens.
- Allows users to send their tokens anywhere with one function
transfer
. No difference between is the receiver a contract or not. No need to learn how token contract is working for regular user to send tokens. - Allows contract developers to handle incoming token transactions.
- ERC223
transfer
to contract consumes 2 times less gas than ERC20approve
andtransferFrom
at receiver contract. - Allows to deposit tokens into contract with a single transaction. Prevents extra blockchain bloating.
- Makes token transactions similar to Ether transactions.
ERC223 tokens are backwards compatible with ERC20 tokens. It means that ERC223 supports every ERC20 functional and contracts or services working with ERC20 tokens will work with ERC223 tokens correctly.
ERC223 tokens should be sent by calling transfer
function on token contract with no difference is receiver a contract or a wallet address. If the receiver is a wallet ERC223 token transfer will be same to ERC20 transfer. If the receiver is a contract ERC223 token contract will try to call tokenReceived
function on receiver contract. If there is no tokenReceived
function on receiver contract transaction will fail. tokenReceived
function is analogue of fallback
function for Ether transactions. It can be used to handle incoming transactions. There is a way to attach bytes _data
to token transaction similar to _data
attached to Ether transactions. It will pass through token contract and will be handled by tokenReceived
function on receiver contract. There is also a way to call transfer
function on ERC223 token contract with no data argument or using ERC20 ABI with no data on transfer
function. In this case _data
will be empty bytes array.
The reason of designing ERC223 token standard.
Here is a description of the ERC20 token standard problem that is solved by ERC223:
ERC20 token standard is leading to money losses for end users. The main problem is lack of possibility to handle incoming ERC20 transactions, that were performed via transfer
function of ERC20 token.
If you send 100 ETH to a contract that is not intended to work with Ether, then it will reject a transaction and nothing bad will happen. If you will send 100 ERC20 tokens to a contract that is not intended to work with ERC20 tokens, then it will not reject tokens because it cant recognize an incoming transaction. As the result, your tokens will get stuck at the contracts balance.
How much ERC20 tokens are currently lost (31 Dec, 2017):
QTUM, $1,358,441 lost. watch on Etherscan
EOS, $1,015,131 lost. watch on Etherscan
GNT, $249,627 lost. watch on Etherscan
STORJ, $217,477 lost. watch on Etherscan
Tronix , $201,232 lost. watch on Etherscan
DGD, $151,826 lost. watch on Etherscan
OMG, $149,941 lost. watch on Etherscan
STORJ, $102,560 lost. watch on Etherscan
MANA, $101,967 lost. watch on Etherscan
Another disadvantages of ERC20 that ERC223 will solve:
- Lack of
transfer
handling possibility. - Loss of tokens.
- Token-transactions should match Ethereum ideology of uniformity. When a user wants to transfer tokens, he should always call
transfer
. It doesn't matter if the user is depositing to a contract or sending to an externally owned account.
Those will allow contracts to handle incoming token transactions and prevent accidentally sent tokens from being accepted by contracts (and stuck at contract's balance).
For example decentralized exchange will no more need to require users to call approve
then call deposit
(which is internally calling transferFrom
to withdraw approved tokens). Token transaction will automatically be handled at the exchange contract.
The most important here is a call of tokenReceived
when performing a transaction to a contract.
ERC20 EIP https://github.com/ethereum/EIPs/issues/20