Are there some plans about generalizing ERC721?
Not using _balances, _owners directly in _update would improve flexibility of OpenZeppelin ERC721. It could be used to write optimal code (bitfields/structs).
Ideas for internal virtual functions:
_balances:
- _decreaseBalance
- _incrementBalance (if it is worth it in gas instead of just using _increaseBalance)
- _decrementBalance(if it is worth it in gas instead of just using _decreaseBalance)
_owners:
- _setOwner
Generalization in _approve:
_tokenApprovals:
- _setApproved