Introduction

Welcome to Lesson 3! In this lesson, we will focus on applying the concepts and syntax we’ve learned from the previous lessons to develop Ethereum smart contracts using Vyper with the Remix IDE. We’ll be creating, deploying, and interacting with simple smart contracts, giving you hands-on experience with Vyper and Ethereum. The first contract will be a simple data storage contract, while the second will simulate a basic voting system.

SimpleStorage: An Introduction to Smart Contracts

The first contract we will deploy is SimpleStorage. This contract, as the name suggests, is a simple data storage contract that stores a single number. SimpleStorage consists of a variable storedData, and two functions, set and get. The set function allows a user to store a number, and the get function allows anyone to retrieve this number.

Deploying and Interacting with SimpleStorage

We will go through the steps to deploy and interact with the SimpleStorage contract on the Ethereum blockchain. Deploying a contract to the Ethereum blockchain is the process of transmitting the contract’s bytecode and ABI to the Ethereum network, from where it can be called and executed. Once a contract is deployed, it receives a unique address at which it can be reached.

Here’s the code for SimpleStorage:

Python
# @title SimpleStorage
storedData: int128

@external
def set(x: int128):
    self.storedData = x

@external
def get() -> int128:
    return self.storedData

In this contract, we define a public integer variable storedData, a public function set(x: int128) to set the value of storedData, and a public constant function get() -> int128 to retrieve the current value of storedData.

Here’s a step-by-step guide on how to deploy this contract using Remix:

1. Open your web browser and navigate to Remix Ethereum IDE.

2. Activate the Vyper Plugin
   

3. Switch the environment to Injected Web3 in the Deploy & Run Transactions section. This will connect Remix to your MetaMask wallet.

4. In the File Explorer section, click on the + icon to create a new file. Name it SimpleStorage.vy.
   

5. Paste the SimpleStorage contract code into this new file.
   

6. Now go to the VyperCompile tab and select the SimpleStorage contract.

7. Switch to the Deploy & Run Transactions tab, and then click on the Deploy button.
   

8. MetaMask will open a transaction confirmation popup. Confirm the transaction.

9. After the transaction is confirmed, you’ll see the deployed SimpleStorage contract in the Deployed Contracts section.

10. You can now interact with the contract. For instance, to store a number, enter the number in the set function and click transact. To retrieve the stored number, click get.

SimpleVoting: A More Complex Contract

After we’ve gotten our feet wet with SimpleStorage, we’ll move onto something a bit more complex: SimpleVoting. The SimpleVoting contract will simulate a simple voting system. We’ll have a list of candidates, each represented as a string. Users will be able to vote for these candidates, and we’ll keep track of the number of votes each candidate received. The contract will provide functions to add a candidate, to vote for a candidate, and to get the total votes a candidate received.

Deploying and Interacting with SimpleVoting

The SimpleVoting contract is a bit more complex than SimpleStorage. In SimpleVoting, we will have a list of candidates, each represented by a string.

Here’s the code for SimpleVoting:

Python
# Vyper Voting Contract

# Declare a state variable `votes` as a HashMap to store the votes for each candidate.
votes: HashMap[bytes32, uint256]

@external
def vote(candidate: bytes32):
    """
    Cast a vote for a candidate.

    Arguments:
    candidate: bytes32 - The identifier of the candidate to vote for.
    """
    # Increment the vote count for the specified candidate.
    self.votes[candidate] += 1

@external
@view
def get_votes(candidate: bytes32) -> uint256:
    """
    Get the total number of votes for a candidate.

    Arguments:
    candidate: bytes32 - The identifier of the candidate to retrieve votes for.

    Returns:
    uint256 - The total number of votes the candidate has received.
    """
    return self.votes[candidate]

This contract is quite basic, with no precautions against double or unauthorised voting. In practise, you would need to include procedures to prevent these difficulties, such as voter registration and a check to ensure that each address can only vote once.

Conclusion and Next Steps

You have created a solid basis for blockchain programming with Vyper by finishing this course. You now have a solid understanding of Ethereum, smart contracts, and how to create them in the Remix IDE with Vyper. This understanding gives up a world of opportunities for developing decentralised applications and participating in the blockchain ecosystem.

To further enhance your skills and knowledge, consider exploring the following areas:

1. Advanced Solidity Programming: Solidity is another popular programming language for Ethereum smart contracts. Learning Solidity will broaden your ability to work with existing contracts and contribute to the Ethereum community. Check our course here: [insert Solidity course Link when online]

2. Decentralized Application (DApp) Development: Dive deeper into building complete decentralized applications by combining smart contracts with front-end development using frameworks like Web3.js, React, or Vue.js. This will enable you to create interactive user interfaces that interact with your smart contracts.

3. Security and Auditing: Explore best practices for securing smart contracts and conducting thorough code audits. Understanding potential vulnerabilities and mitigating risks will ensure the reliability and safety of your smart contracts.

4. Blockchain Interoperability: Investigate the integration of different blockchain networks and protocols. Learn about cross-chain communication and the development of interoperable smart contracts that can interact with multiple blockchains.
   Remember, blockchain technology is constantly evolving, and it is crucial to stay updated with the latest advancements. Engage with the blockchain community, actively participate in discussions, and explore new concepts and technologies to stay informed and up-to-date.