If you've been dipping your toes in the awesome Rust language, you must've encountered the clone() method which is present in almost every object out there to make a deep copy of it. It comes from the implementation of Clone trait for a struct.

In the previous part (Part 1) we understood some facts about solidity compiler and wrote the Box contract's functions using inline assembly i.e. in Yul. This part would guide you to writing the Box contract in pure assembly. As a reminder here is the Box contract with inline assembly from previous part:

In the previous part (Part 0) we covered some pre-requisite knowledge of EVM. In this part, we will write the Box contract partially in assembly - the function bodies of retrieve() and store(). Here is our Box contract in Solidity:

Solidity is by far the most used language for smart contracts on Ethereum blockchain. It is a high-level language that abstracts away various underlying nitty-gritty details (like several important safety checks) - and that is for good!

Before you move further I assume you already of some Solidity experience and know how storage slots work in any contract.

Before you continue, I'm assuming you know what The Graph is and what problems it tackles. If you haven't, I highly recommend checking out - Why The Graph.

I'm assuming the reader of this article has prior experience in writing basic smart contracts, at minimum. If not, it's a great time to start.

Tokens are arguably one of the most powerful tools in the blockchain right now. A token can be a representation of anything on-chain — be it voting weight, shares in the company, or virtual assets (aka NFTs). A smart contract stores who has what token and how much of it. It also takes care of the business logic of transfers, trades, loans, etc. Tokens are nothing but a mapping of what token belongs to what address (or account) inside the smart contract. So, when you transfer your token to someone else, that mapping changes so that the traded token maps to the receiver’s address.