Writing the NFT marketplace smart contract

As usual, let’s create the Ape project by running these commands:

$ python3 -m venv .venv
(.venv) $ pip install eth-ape'[recommended-plugins]'==0.7.23
(.venv) $ mkdir nft_marketplace
(.venv) $ cd nft_marketplace
(.venv) $ ape init
Please enter project name: NFT Marketplace
SUCCESS: NFT Marketplace is written in ape-config.yaml

Then create a smart contract file inside the contracts folder named NFTMarketplace.vy and add the following code to it:

#pragma version ^0.3.0
interface ERC721_Interface:
    def transferFrom(_from: address, _to: address, _tokenId: uint256): nonpayable
    def ownerOf(_tokenId: uint256) -> address: view

The pragma line specifies that this smart contract can only be compiled using version 0.3.x of the Vyper compiler.

Then there are two ERC721 interfaces that you register in the smart contract because the NFT marketplace smart contract will interact...