The ERC-223 Evolution

Disclaimer: I use the term ERC-223 very lightly. There is no consensus from the community as to whether the EIP will ever see the light of day. That being said, it is a good exercise to think through the problem it attempts to solve and lend your voice to the discussion.

Full project source is available — here

Ethereum has had its share of disasters regarding the loss of tokens as have most of the blockchain projects in the crypto space. Some of these losses have been sophisticated attacks on smart contracts and some token holders have simply sent their tokens to the wrong address. If you sent your ERC20 tokens to someone by mistake and they were in a good mood, you may get them back. If you sent them to a smart contract address, you can kiss them goodbye. They are gone. The ERC223 EIP request is currently under review by the Ethereum team that can be found here.

Purpose of this article

This article will attempt to create an ERC-223 in its simplest useful form using the OpenZeppelin implementation of an ERC-20 token and implementing the suggested ERC-223 methods. We will also be creating tests to illustrate the usage of the ‘fallback’ method on which the ERC-223 spec relies in order to fully illustrate the usage of this in practice.

Setup the project

Make sure that you have node, npm and truffle installed

mkdir erc223 && cd erc223 && truffle init

Replace the truffle.js content with the following:

Install Ganache and make sure it is running on 8545

Compile and Migrate

truffle compile
truffle migrate

Init the folder as an npm project

npm init

Install zeppelin dependency

npm install zeppelin-solidity

The Tokens

Add the following to /contracts as MyERC223.sol

Add the following to /contracts as ERC223ReceivingContract.sol . This is the interface that our erc223-compliant smart contracts must adhere to.

The interface an erc223-compliant smart contract must adhere to

Add the following to /contracts as MyERC20.sol . Note that this is for us to test the ERC20 token recovery function of the zeppelin contract, HasNoTokens.sol

Add the following migration to /migrations as 2_erc_migration.js

The Contracts

Add the following to /contracts as BalanceContract.sol

This contract manually implements the erc223 fallback method

Add the following to /contracts as SafeContract.sol

This contract implements the zeppelin HasNoTokens.sol contract that implements the erc223 fallback method

Add the following to /contracts as UnsafeContract.sol

This contract is unsafe for erc20 but safe for erc223

Add the following migration to /migrations as 3_contract_migration.js

Compile and Migrate

Run the compile script and verify that it compiles without errors

Marks-MacBook-Pro:erc223 markmathis$ truffle compile

Run the migrate script and verify that it deploys without errors

Marks-MacBook-Pro:erc223 markmathis$ truffle migrate

Test it out

Install test libraries

npm install chai --save-dev
npm install chai-as-promised --save-dev
npm install babel-preset-es2015 --save-dev
npm install babel-register --save-dev
npm install babel-polyfill --save-dev

Add .babelrc to project root

{
  "presets": ["es2015"]
}

Add erc223.spec.js to /test

Run the test from the project root

truffle test

What’s happening…

The above tests ensure the following:

• ERC223 tokens cannot be transferred to a contract address that does not implement the fallback method defined in ERC223ReceivingContract.sol
• ERC223 tokens cannot be transferred to a contract address that implements the HasNoTokens.sol zeppelin contract
• ERC223 tokens can be transferred to a contract that correctly implements the fallback method defined in ERC223ReceivingContract.sol in the case that the contract does in fact support a balance.
• ERC20 tokens sent to a contract that implements the HasNoTokens.sol zeppelin contract can be retrieved by the OWNER OF THE CONTRACT. Note that if you send your ERC20 tokens to one of these contracts the OWNER can request to retrieve the tokens to their account and then distribute back to you if you are so lucky.

Additional Resources

Dexaran/ERC223-token-standard

Create your own Ethereum token (Part 2: ERC223)

Full project source is available — here