In the ERC721 standard, there is a Wallet interface standard called ERC721TokenReceiver which includes a function called onERC721Received. I believe this is so that Wallets can listen to events and update the balance of the wallet (please correct me if not).

What are other design pattern uses of "Solidity callbacks"?

2 Answers 2


ERC-721 is the only final status ERC that includes such a call back design.

Source: https://eips.ethereum.org/erc

You can also see ERC-777 which is in draft form and it makes a deeper use of callbacks.

Source: https://eips.ethereum.org/EIPS/eip-777


ERC777 is now final and OpenZeppelin 2.3.0 includes an ERC777 implementation.

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