... still bad pattern and there was still an unsafe external call.
imBTC-EIP 777
deposit dai first, bring the pool unbalanced
![image-20210801210143415](image/![image20210801210143415.png]![image20210801210143415.png](https://img.learnblockchain.cn/attachments/2021/09/Qu0jryRw6151d2804711f.p...
...C721 Non-Fungible Token Standard basic implementation
* @dev see https://eips.ethereum.org/EIPS/eip-721
*/
contract ERC721 is Context, ERC165, IERC721, IERC721Metadata, IERC721Enumerable {
using SafeMath for uint256;
using Address for address;
using EnumerableSet for EnumerableSe...
...ccounts just\n * by listening to said events. Other implementations of the EIP may not emit\n * these events, as it isn't required by the specification.\n *\n * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}\n * functions have been added to mitigate the well-known issues aroun...