Mastering Blockchain Programming with Solidity

Token transfer does not notify the contact

If you have a contract that should trigger another action once ETH is received on the contract, you can write a fallback function in the contract and call the appropriate function or event to notify it. However, with the ERC20 token standard APIs, it is not possible to get notifications of another action being triggered when an ERC20 standard-specific token is received at the deployed contract. The token transfers are received at the contract silently.

There are some other standards that can be used for this purpose. The ERC223 standard provides the methods that will be called once the tokens are transferred. However, the ERC223 standard is not fully backward compatible with ERC20. Very few companies ...