Can i extend an ERC721 function?

Question

I wonder is it is possible to extend the ERC721 functions that handles transfering tokens. I want to have a variable, and change its state if an nft has been transferred to someone else. Is that possible, without breaking the ERC721 standard? If possible, how would i exactly do that?

I saw this question, but it doesnt really answer my question if it is possible and how.

Answer 1

Yes you can. And we definitely welcome your innovation and extension here.

In your smart contract you will just use an existing ERC-721 implementation, inherit from that contract and then implement your function something like this:

function _transfer(...) {
   // Update a counter for the token recipient
   super._transfer(...);
}