[Ethereum] Lazy Minting in Ethereum

The answer is in the name of the token : SuperRare.

There is a negative correlation between the value of an asset and its total supply, even when the tokens are non fongible.

That's why we see some NFTs being sold for 100 ETH.

Holders can be both creators and collectors :

• creators when the NFT is minted, it can then be put in auction for exemple
• collectors when the NFT is traded.

For the submit token burn details info I believe this is an option for the contract owner who can communicate to Etherscan the token’s burn history.

UPDATE

The SuperRare smart contract implements ERC721Enumerable. In this contract we have the array _allTokens counting the number of NFTs :

  // Array with all token ids, used for enumeration
  uint256[] private _allTokens;

Then we have the totalSupply function which returns the length of the previous array :

  /**
  * @dev Gets the total amount of tokens stored by the contract
  * @return uint256 representing the total amount of tokens
  */
 function totalSupply() public view returns (uint256) {
   return _allTokens.length;
 }

Note that (unlike ERC20), the totalSupply method is not part of the base ERC721 standard, but is implemented by ERC721Enumerable which is an enumeration extension smart contract for ERC721.

Finally the mint function :

  /**
   * @dev Internal function to mint a new token
   * Reverts if the given token ID already exists
   * @param to address the beneficiary that will own the minted token
   * @param tokenId uint256 ID of the token to be minted by the 
msg.sender
   */
  function _mint(address to, uint256 tokenId) internal {
    super._mint(to, tokenId);

    _allTokensIndex[tokenId] = _allTokens.length;
    _allTokens.push(tokenId);
  }

We can see the _allTokens array is incremented after a mint. Conversely, it is decremented after a burn. The totalSupply is therefore not fixed, which is logical given the ambition of the project to create an art marketplace.

Lazy minting or "Gas Free" minting can be done using both the ERC1155 standard or the ERC721 standard. There is certainly nothing preventing OpenSea and other marketplaces from using an ERC721 for lazy minting.

The reason ERC1155 is becoming the popular choice for lazy minting is because:

• You have the ability to create Fungible and Non-Fungible assets
• ERC1155s uses ID substitution pattern in the uri() function. This allows for easy linkage to the metadata with just the tokenId which makes it easier to lazy mint.
• There is a large reduction in gas cost when using ERC1155 that increases the users experience.

Using the two basic examples below from OpenZeppelin we can see the gas savings:

• Minting with an ERC721 costs 96,073
• Safe Transfer for ERC721 costs 61,542
• Minting with an ERC1155 costs 51,935
• Safe Transfer for ERC1155 costs 53,492

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.3;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/token/ERC1155/ERC1155.sol";


contract MyERC721 is ERC721, ERC721URIStorage, Ownable {
    constructor() ERC721("MyToken", "MTK") {}

    function safeMint(address to, uint256 tokenId, string memory uri)
        public
        onlyOwner
    {
        _safeMint(to, tokenId);
        _setTokenURI(tokenId, uri);
    }

    // The following functions are overrides required by Solidity.

    function _burn(uint256 tokenId) internal override(ERC721, ERC721URIStorage) {
        super._burn(tokenId);
    }

    function tokenURI(uint256 tokenId)
        public
        view
        override(ERC721, ERC721URIStorage)
        returns (string memory)
    {
        return super.tokenURI(tokenId);
    }
}

contract MyERC1155 is ERC1155, Ownable {
    constructor() ERC1155("") {}

    function setURI(string memory newuri) public onlyOwner {
        _setURI(newuri);
    }

    function mint(address account, uint256 id, uint256 amount, bytes memory data)
        public
        onlyOwner
    {
        _mint(account, id, amount, data);
    }

    function mintBatch(address to, uint256[] memory ids, uint256[] memory amounts, bytes memory data)
        public
        onlyOwner
    {
        _mintBatch(to, ids, amounts, data);
    }
}

How can ERC1155 help with low gas fees?

ERC1155 helps with low gas fees even with basic transfer transactions because it stores data more efficiently inside the contract. If you look inside the OpenZeppelin ERC1155 contract you will see that you only need to update two mappings to transfer the token.

_balances[id][from] = fromBalance - amount;
_balances[id][to] += amount;

But for the ERC721 you have to update 3 mappings which raises the gas cost

_balances[from] -= 1;
_balances[to] += 1;
_owners[tokenId] = to;