143 lines
4.2 KiB
Markdown
143 lines
4.2 KiB
Markdown
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---
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eip: 5007
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title: Time NFT, EIP-721 Time Extension
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description: Add start time and end time to EIP-721 tokens.
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author: Anders (@0xanders), Lance (@LanceSnow), Shrug <shrug@emojidao.org>
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discussions-to: https://ethereum-magicians.org/t/eip-5007-eip-721-time-extension/8924
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status: Last Call
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last-call-deadline: 2022-09-25
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type: Standards Track
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category: ERC
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created: 2022-04-13
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requires: 165, 721
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---
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## Abstract
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This standard is an extension of [EIP-721](./eip-721.md). It proposes some additional functions (`startTime`, `endTime`) to help with on-chain time management.
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## Motivation
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Some NFTs have a defined usage period and cannot be used outside of that period. With traditional NFTs that do not include time information, if you want to mark a token as invalid or enable it at a specific time, you need to actively submit a transaction—a process both cumbersome and expensive.
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Some existing NFTs contain time functions, but their interfaces are not consistent, so it is difficult to develop third-party platforms for them.
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By introducing these functions (`startTime`, `endTime`), it is possible to enable and disable NFTs automatically on chain.
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## Specification
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The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY" and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.
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```solidity
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/**
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* @dev the EIP-165 identifier for this interface is 0x7a0cdf92.
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*/
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interface IERC5007 /* is IERC721 */ {
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/**
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* @dev Returns the start time of the NFT as a UNIX timestamp.
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*
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* Requirements:
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*
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* - `tokenId` must exist.
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*/
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function startTime(uint256 tokenId) external view returns (int64);
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/**
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* @dev Returns the end time of the NFT as a UNIX timestamp.
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*
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* Requirements:
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*
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* - `tokenId` must exist.
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*/
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function endTime(uint256 tokenId) external view returns (int64);
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}
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```
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The **composable extension** is OPTIONAL for this standard. This allows your NFT to be minted from an existing NFT or to merge two NFTs into one NFT.
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```solidity
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/**
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* @dev the EIP-165 identifier for this interface is 0x620063db.
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*/
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interface IERC5007Composable /* is IERC5007 */ {
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/**
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* @dev Returns the ancestor token id of the NFT.
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*
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* Requirements:
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*
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* - `tokenId` must exist.
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*/
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function rootTokenId(uint256 tokenId) external view returns (uint256);
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/**
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* @dev Mint a new token from an old token.
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* The rootTokenId of the new token is the same as the rootTokenId of the old token
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*
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* Requirements:
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*
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* - `oldTokenId` must exist.
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* - `newTokenId` must not exist.
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* - `newTokenOwner` cannot be the zero address.
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* - `newTokenStartTime` require(oldTokenStartTime < newTokenStartTime && newTokenStartTime <= oldTokenEndTime)
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*/
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function split(
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uint256 oldTokenId,
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uint256 newTokenId,
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address newTokenOwner,
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int64 newTokenStartTime
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) external;
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/**
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* @dev Merge the first token and second token into the new token.
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*
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* Requirements:
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*
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* - `firstTokenId` must exist.
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* - `secondTokenId` must exist. require((firstToken.endTime + 1) == secondToken.startTime)
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* - `newTokenOwner` cannot be the zero address.
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* - `newTokenId` must not exist.
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*/
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function merge(
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uint256 firstTokenId,
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uint256 secondTokenId,
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address newTokenOwner,
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uint256 newTokenId
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) external;
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}
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```
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## Rationale
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### Time Data Type
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The max value of `int64` is 9,223,372,036,854,775,807. As a timestamp, 9,223,372,036,854,775,807 is about year 292,471,210,648. `uint256` is too big for C, C++, Java, Go, etc, and `int64` is natively supported by mainstream programming languages.
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## Backwards Compatibility
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This standard is fully EIP-721 compatible.
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## Test Cases
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Test cases are included in [test.js](../assets/eip-5007/test/test.js).
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Run in terminal:
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```shell
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cd ../assets/eip-5007
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npm install
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truffle test
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```
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## Reference Implementation
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See [`ERC5007.sol`](../assets/eip-5007/contracts/ERC5007.sol).
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## Security Considerations
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No security issues found.
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## Copyright
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Copyright and related rights waived via [CC0](../LICENSE.md).
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