ERC-223 hub. Here you can track the progress and find all the necessary resources about ERC-223 standard: https://dexaran.github.io/erc223/
eip: 223
title: ERC-223 Token
description: Token with event handling and communication model
author: Dexaran (@Dexaran) dexaran@ethereumclassic.org
status: Review
type: Standards Track
category: ERC
created: 2017-05-03
Simple Summary
A standard interface for tokens with definition of communication model logic. I am creating this issue here because I want to submit a final PR to the EIPs repo and it requires a link to this forum now.
Old discussion thread with 600+ comments from developers can be found under EIP223
Abstract
The following describes standard functions a token contract and contract working with specified token can implement. This standard introduces a communication model which allows for the implementation of event handling on the receiver’s side.
Motivation
- This token introduces a communication model for contracts that can be utilized to straighten the behavior of contracts that interact with tokens as opposed to ERC-20 where a token transfer could be ignored by the receiving contract.
- This token is more gas-efficient when depositing tokens to contracts.
- This token allows for
_datarecording for financial transfers.
Rationale
This standard introduces a communication model by enforcing the transfer to execute a handler function in the destination address. This is an important security consideration as it is required that the receiver explicitly implements the token handling function. In cases where the receiver does not implements such function the transfer MUST be reverted.
This standard sticks to the push transaction model where the transfer of assets is initiated on the senders side and handled on the receivers side. As the result, ERC223 transfers are more gas-efficient while dealing with depositing to contracts as ERC223 tokens can be deposited with just one transaction while ERC20 tokens require at least two calls (one for approve and the second that will invoke transferFrom).
-
ERC-20 deposit:
approve~53K gas,transferFrom~80K gas -
ERC-223 deposit:
transferand handling on the receivers side ~46K gas
This standard introduces the ability to correct user errors by allowing to handle ANY transactions on the recipient side and reject incorrect or improper transactions. This tokens utilize ONE transferring method for both types of interactions with tokens and externally owned addresses which can simplify the user experience and allow to avoid possible user mistakes.
One downside of the commonly used ERC-20 standard that ERC-223 is intended to solve is that ERC-20 implements two methods of token transferring: (1) transfer function and (2) approve + transferFrom pattern. Transfer function of ERC20 standard does not notify the receiver and therefore if any tokens are sent to a contract with the transfer function then the receiver will not recognize this transfer and the tokens can become stuck in the receivers address without any possibility of recovering them.
ERC223 standard is intended to simplify the interaction with contracts that are intended to work with tokens. ERC-223 utilizes “deposit” pattern similar to plain Ether depositing patterns - in case of ERC-223 deposit to the contract a user or a UI must simply send the tokens with the transfer function. This is one transaction as opposed to two step process of approve + transferFrom depositing.
This standard allows payloads to be attached to transactions using the bytes calldata _data parameter, which can encode a second function call in the destination address, similar to how msg.data does in an Ether transaction, or allow for public loggin on chain should it be necessary for financial transactions.
Specification
Token
Contracts that works with tokens
Methods
NOTE: An important point is that contract developers must implement tokenReceived if they want their contracts to work with the specified tokens.
If the receiver does not implement the tokenReceived function, consider the contract is not designed to work with tokens, then the transaction must fail and no tokens will be transferred. An analogy with an Ether transaction that is failing when trying to send Ether to a contract that did not implement function() payable.
totalSupply
function totalSupply() constant returns (uint256 totalSupply)
Get the total token supply
name
function name() constant returns (string _name)
Get the name of token
symbol
function symbol() constant returns (bytes32 _symbol)
Get the symbol of token
decimals
function decimals() constant returns (uint8 _decimals)
Get decimals of token
standard
function standard() constant returns (string _standard)
Get the standard of token contract. For some services it is important to know how to treat this particular token. If token supports ERC223 standard then it must explicitly tell that it does.
This function MUST return “erc223” for this token standard. If no “standard()” function is implemented in the contract then the contract must be considered to be ERC20.
balanceOf
function balanceOf(address _owner) constant returns (uint256 balance)
Get the account balance of another account with address _owner
transfer(address, uint)
function transfer(address _to, uint _value) returns (bool)
Needed due to backwards compatibility reasons because of ERC20 transfer function doesn’t have bytes parameter. This function must transfer tokens and invoke the function tokenReceived(address, uint256, bytes calldata) in _to, if _to is a contract. If the tokenReceived function is not implemented in _to (receiver contract), then the transaction must fail and the transfer of tokens should be reverted.
transfer(address, uint, bytes)
function transfer(address _to, uint _value, bytes calldata _data) returns (bool)
function that is always called when someone wants to transfer tokens.
This function must transfer tokens and invoke the function tokenReceived (address, uint256, bytes) in _to, if _to is a contract. If the tokenReceived function is not implemented in _to (receiver contract), then the transaction must fail and the transfer of tokens should not occur.
If _to is an externally owned address, then the transaction must be sent without trying to execute tokenReceived in _to.
_data can be attached to this token transaction and it will stay in blockchain forever (requires more gas). _data can be empty.
NOTE: The recommended way to check whether the _to is a contract or an address is to assemble the code of _to. If there is no code in _to, then this is an externally owned address, otherwise it’s a contract.
Events
Transfer
event Transfer(address indexed _from, address indexed _to, uint256 _value)
Triggered when tokens are transferred. Compatible with ERC20 Transfer event.
TransferData
event TransferData(bytes _data)
Triggered when tokens are transferred and logs transaction metadata. This is implemented as a separate event to keep Transfer(address, address, uint256) ERC20-compatible.
Contract that is intended to receive ERC223 tokens
function tokenReceived(address _from, uint _value, bytes calldata _data)
A function for handling token transfers, which is called from the token contract, when a token holder sends tokens. _from is the address of the sender of the token, _value is the amount of incoming tokens, and _data is attached data similar to msg.data of Ether transactions. It works by analogy with the fallback function of Ether transactions and returns nothing.
NOTE: msg.sender will be a token-contract inside the tokenReceived function. It may be important to filter which tokens are sent (by token-contract address). The token sender (the person who initiated the token transaction) will be _from inside the tokenReceived function.
IMPORTANT: This function must be named tokenReceived and take parameters address, uint256, bytes to match the function signature 0xc0ee0b8a.
Security Considerations
This token utilizes the model similar to plain Ether behavior. Therefore replay issues must be taken into account.
Copyright
Copyright and related rights waived via CC0