From cc8ac5381db512c26017b65103c548b7d1d88148 Mon Sep 17 00:00:00 2001 From: Bernardo Ramos Date: Wed, 20 Sep 2023 21:56:10 -0300 Subject: [PATCH] readme: add warning about callback function --- README.md | 26 ++++++++++++++++++++++++-- 1 file changed, 24 insertions(+), 2 deletions(-) diff --git a/README.md b/README.md index 6e2b767..052416e 100644 --- a/README.md +++ b/README.md @@ -556,7 +556,15 @@ Check instructions bellow for usage and examples ### Hook -Contracts that want to handle tokens must implement the following function to define how to handle the tokens they receive. If this function is not implemented, the token transfer will fail. Therefore, it is possible to prevent the token from being lost. +This function is required to receive ARC2 non-fungible tokens + +Contracts that want to receive non-fungible tokens must implement the following function in order to receive them. +In most cases it also means that your contract must have methods to transfer these tokens. + +If your contract is not intended to handle non-fungible tokens, then do not add this function. In this case any +attempt to transfer a NFT to your contract will fail (as expected). + +This function can also be used to define how to handle the tokens they receive. ``` lua -- The ARC2 smart contract calls this function on the recipient contract after a 'transfer' or 'mint' @@ -565,9 +573,23 @@ Contracts that want to handle tokens must implement the following function to de -- @param from (address) the sender's address (nil if being minted) -- @param tokenId (str128) the non-fungible token id -- @param ... additional data, by-passed from 'transfer' or 'mint' arguments -function nonFungibleReceived(operator, from, tokenId, ...) end +function nonFungibleReceived(operator, from, tokenId, ...) + -- do nothing +end ``` +> :warning: **ATTENTION:** anyone can call this function! :warning: +> +> Do NOT assume a token was received just because this function was called! + +If a token was really sent, we can get the token contract address with: + +```lua +local token_contract = system.getSender() +``` + +But on most cases the function can be empty. + ### List and Find Tokens