Why design patterns improve quality in Blockchain / Solidity - See It in Action

Why Design Patterns Improve Quality in Blockchain

📖 Scenario: Imagine you are building a simple blockchain system. You want to make sure your code is easy to understand, maintain, and extend. Using design patterns helps you do this by giving you proven ways to organize your code.

🎯 Goal: You will create a simple blockchain data structure, add a configuration for difficulty, implement a basic proof-of-work mining function using a design pattern approach, and finally print the mined block's hash.

📋 What You'll Learn

Create a list called blockchain with one dictionary representing the genesis block

Create a variable called difficulty set to 2

Write a function called mine_block that takes a block and finds a nonce so that the block's hash starts with difficulty number of zeros

Print the hash of the mined block

💡 Why This Matters

🌍 Real World

Blockchain systems use design patterns like Proof of Work to secure transactions and make the system reliable and maintainable.

💼 Career

Understanding design patterns in blockchain development is important for building secure, efficient, and scalable decentralized applications.

1

DATA SETUP: Create the initial blockchain

Create a list called blockchain with one dictionary representing the genesis block. The dictionary should have keys: index with value 0, data with value 'Genesis Block', and nonce with value 0.

Blockchain / Solidity

# Create the blockchain list with the genesis block
# Your code here

Need a hint?

The blockchain is a list of blocks. Each block is a dictionary with keys index, data, and nonce.

2

CONFIGURATION: Set mining difficulty

Create a variable called difficulty and set it to 2. This will control how many zeros the hash must start with.

Blockchain / Solidity

blockchain = [{'index': 0, 'data': 'Genesis Block', 'nonce': 0}]
# Set the mining difficulty
# Your code here

Need a hint?

Difficulty is a number that tells how hard it is to mine a block. Here, 2 means the hash must start with two zeros.

3

CORE LOGIC: Implement mining function

Write a function called mine_block that takes a block dictionary as input. Use a while loop to find a nonce value so that the SHA-256 hash of the string formed by concatenating the block's index, data, and nonce starts with difficulty number of zeros. Update the block's nonce with the found value and return the block's hash.

Blockchain / Solidity

blockchain = [{'index': 0, 'data': 'Genesis Block', 'nonce': 0}]
difficulty = 2

# Write the mine_block function below
# Your code here

Need a hint?

Use a loop to try different nonce values until the hash starts with the required zeros. Use hashlib.sha256 to get the hash.

4

OUTPUT: Print the mined block's hash

Call the mine_block function with the first block in blockchain and print the returned hash.

Blockchain / Solidity

import hashlib

blockchain = [{'index': 0, 'data': 'Genesis Block', 'nonce': 0}]
difficulty = 2

def mine_block(block):
    nonce = 0
    prefix = '0' * difficulty
    while True:
        text = f"{block['index']}{block['data']}{nonce}"
        block_hash = hashlib.sha256(text.encode()).hexdigest()
        if block_hash.startswith(prefix):
            block['nonce'] = nonce
            return block_hash
        nonce += 1

# Call mine_block on the first block and print the hash
# Your code here

Need a hint?

The printed hash should start with two zeros because difficulty is 2.