EIP协议学习2

EIP-721 Specification

pragma solidity ^0.4.20;

/// @title ERC-721 Non-Fungible Token Standard
/// @dev See https://eips.ethereum.org/EIPS/eip-721
///  Note: the ERC-165 identifier for this interface is 0x80ac58cd.
interface ERC721 /* is ERC165 */ {
 /// @dev This emits when ownership of any NFT changes by any mechanism.
 ///  This event emits when NFTs are created (`from` == 0) and destroyed
 ///  (`to` == 0). Exception: during contract creation, any number of NFTs
 ///  may be created and assigned without emitting Transfer. At the time of
 ///  any transfer, the approved address for that NFT (if any) is reset to none.
 <在任何机制下，当NFT的所有权发生改变的时候会触发。在NFT创建（from=0）和销毁（to=0）的时候会触发该事件，在任何时候进行转移时，NFT批转的地址将会被重置为none>
 event Transfer(address indexed _from, address indexed _to, uint256 indexed _tokenId);

 /// @dev This emits when the approved address for an NFT is changed or
 ///  reaffirmed. The zero address indicates there is no approved address.
 ///  When a Transfer event emits, this also indicates that the approved
 ///  address for that NFT (if any) is reset to none.
 <这个事件在NFT的许可地址被更改或者重复确认的时候会触发，0地址代表没有许可的地址，当Transfer事件发生的时候，这也标志许可地址被重置为none>
 event Approval(address indexed _owner, address indexed _approved, uint256 indexed _tokenId);

 /// @dev This emits when an operator is enabled or disabled for an owner.
 ///  The operator can manage all NFTs of the owner.
 <这个操作触发可以让owner拥有或者禁用对于所有NFT所有这的管理权>
 event ApprovalForAll(address indexed _owner, address indexed _operator, bool _approved);

 /// @notice Count all NFTs assigned to an owner
 /// @dev NFTs assigned to the zero address are considered invalid, and this
 ///  function throws for queries about the zero address.
 /// @param _owner An address for whom to query the balance
 /// @return The number of NFTs owned by `_owner`, possibly zero
 <同EIP-20-balanceOf>
 function balanceOf(address _owner) external view returns (uint256);

 /// @notice Find the owner of an NFT
 /// @dev NFTs assigned to zero address are considered invalid, and queries
 ///  about them do throw.
 /// @param _tokenId The identifier for an NFT
 /// @return The address of the owner of the NFT
 <传入NTF代币的token，返回NFT拥有者的地址>
 function ownerOf(uint256 _tokenId) external view returns (address);

 /// @notice Transfers the ownership of an NFT from one address to another address
 /// @dev Throws unless `msg.sender` is the current owner, an authorized
 ///  operator, or the approved address for this NFT. Throws if `_from` is
 ///  not the current owner. Throws if `_to` is the zero address. Throws if
 ///  `_tokenId` is not a valid NFT. When transfer is complete, this function
 ///  checks if `_to` is a smart contract (code size > 0). If so, it calls
 ///  `onERC721Received` on `_to` and throws if the return value is not
 ///  `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`.
 /// @param _from The current owner of the NFT
 /// @param _to The new owner
 /// @param _tokenId The NFT to transfer
 /// @param data Additional data with no specified format, sent in call to `_to`
 <如果消息发送方不是NFT许可地址或者授权的操作者，抛出异常；如果发送方不是当前的地址抛出异常；如果目标地址to是0地址抛出异常；如果tokenid不是有效的NFT标识，抛出异常；如果to地址对象是一个智能合约地址，那么必须要调用onERC721Received，如果返回值是no抛出异常>
 function safeTransferFrom(address _from, address _to, uint256 _tokenId, bytes data) external payable;

 /// @notice Transfers the ownership of an NFT from one address to another address
 /// @dev This works identically to the other function with an extra data parameter,
 ///  except this function just sets data to "".
 /// @param _from The current owner of the NFT
 /// @param _to The new owner
 /// @param _tokenId The NFT to transfer
 <同上面一样，只是相当于将data设置为"">
 function safeTransferFrom(address _from, address _to, uint256 _tokenId) external payable;

 /// @notice Transfer ownership of an NFT -- THE CALLER IS RESPONSIBLE
 ///  TO CONFIRM THAT `_to` IS CAPABLE OF RECEIVING NFTS OR ELSE
 ///  THEY MAY BE PERMANENTLY LOST
 /// @dev Throws unless `msg.sender` is the current owner, an authorized
 ///  operator, or the approved address for this NFT. Throws if `_from` is
 ///  not the current owner. Throws if `_to` is the zero address. Throws if
 ///  `_tokenId` is not a valid NFT.
 /// @param _from The current owner of the NFT
 /// @param _to The new owner
 /// @param _tokenId The NFT to transfer
 <同上面safeTransferFrom，缺少判断一个to为合约地址>
 function transferFrom(address _from, address _to, uint256 _tokenId) external payable;

 /// @notice Change or reaffirm the approved address for an NFT
 /// @dev The zero address indicates there is no approved address.
 ///  Throws unless `msg.sender` is the current NFT owner, or an authorized
 ///  operator of the current owner.
 /// @param _approved The new approved NFT controller
 /// @param _tokenId The NFT to approve
 <0地址表示没有许可的地址，如果当前发送者不是NFT拥有者或者许可操作者，抛出异常>
 function approve(address _approved, uint256 _tokenId) external payable;

 /// @notice Enable or disable approval for a third party ("operator") to manage
 ///  all of `msg.sender`'s assets
 /// @dev Emits the ApprovalForAll event. The contract MUST allow
 ///  multiple operators per owner.
 /// @param _operator Address to add to the set of authorized operators
 /// @param _approved True if the operator is approved, false to revoke approval
 <发送ApprovalForAll事件，这个合同必须允许每个拥有者有多个操作者>
 function setApprovalForAll(address _operator, bool _approved) external;

 /// @notice Get the approved address for a single NFT
 /// @dev Throws if `_tokenId` is not a valid NFT.
 /// @param _tokenId The NFT to find the approved address for
 /// @return The approved address for this NFT, or the zero address if there is none
 <抛出tokenid不是正确NFT的异常，返回被NFT许可的地址，如果没有许可地址则返回0地址>
 function getApproved(uint256 _tokenId) external view returns (address);

 /// @notice Query if an address is an authorized operator for another address
 /// @param _owner The address that owns the NFTs
 /// @param _operator The address that acts on behalf of the owner
 /// @return True if `_operator` is an approved operator for `_owner`, false otherwise
 <检验operator是否有操作的权限，返回true或者false>
 function isApprovedForAll(address _owner, address _operator) external view returns (bool);
}

interface ERC165 {
 /// @notice Query if a contract implements an interface
 /// @param interfaceID The interface identifier, as specified in ERC-165
 /// @dev Interface identification is specified in ERC-165. This function
 ///  uses less than 30,000 gas.
 /// @return `true` if the contract implements `interfaceID` and
 ///  `interfaceID` is not 0xffffffff, `false` otherwise
 function supportsInterface(bytes4 interfaceID) external view returns (bool);
}