BaseLearn - Solidity Learning Exercises 🎓

A collection of Solidity smart contracts implementing solutions to the Base Learn exercises. This repository contains progressive learning exercises covering fundamental to advanced Solidity concepts.

📚 Table of Contents

• Overview
• Prerequisites
• Quick Start
• Exercises & Contracts
• Deployment Scripts
• Development Workflow
• Testing
• Contributing

🎯 Overview

This codebase contains solutions to Base's Solidity learning curriculum, covering:

• Basic Math Operations with overflow/underflow protection
• Control Structures and conditional logic
• Storage Optimization and variable packing
• Arrays & Mappings manipulation
• Structs and complex data types
• Inheritance patterns and abstract contracts
• Import Systems and library usage
• Error Handling and debugging techniques
• Factory Patterns with the new keyword
• ERC-20 Tokens with voting mechanisms
• ERC-721 NFTs with unique content validation
• Custom Token implementations

⚡ Prerequisites

• Node.js (v16 or higher)
• Foundry toolkit
• Git
• Basic understanding of Solidity and Ethereum

Install Foundry

curl -L https://foundry.paradigm.xyz | bash
foundryup

🚀 Quick Start

1. Clone the repository

   git clone https://github.com/rionnaldi/BaseLearn.git
   cd BaseLearn

2. Install dependencies

   forge install

3. Build all contracts

   forge build

4. Run tests

   forge test

5. Deploy a contract (example)

   forge script script/DeployBasicMath.s.sol --rpc-url <your_rpc_url> --private-key <your_private_key> --broadcast

📋 Exercises & Contracts

1. BasicMath.sol - Math Operations with Safety

// Handles addition/subtraction with overflow/underflow detection
function adder(uint256 _a, uint256 _b) external returns (uint256 sum, bool error)
function subtractor(uint256 _a, uint256 _b) external returns (uint256 difference, bool error)

Key Features: Overflow protection, error flags, safe arithmetic

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2. EmployeeStorage.sol - Storage Optimization

// Optimized storage with variable packing
uint16 private shares;     // Packed with salary in same slot
uint24 private salary;     // Up to 16M salary range

Key Features: Variable packing, custom errors, access control

---

3. ArraysExercise.sol - Array Manipulation

// Dynamic array operations
function appendToNumbers(uint[] calldata _toAppend) public
function afterY2K() public view returns (uint[] memory, address[] memory)

Key Features: Dynamic arrays, filtering, timestamp handling

---

4. FavoriteRecords.sol - Mapping Usage

// Nested mappings for user preferences
mapping(address => mapping(string => bool)) public userFavorites;

Key Features: Nested mappings, approval systems, custom errors

---

5. GarageManager.sol - Structs & Storage

struct Car {
    string make;
    string model; 
    string color;
    uint8 numberOfDoors;  // Gas-optimized
}

Key Features: Struct optimization, CRUD operations, index validation

---

6. InheritanceExercise.sol - Advanced Inheritance

// Multiple inheritance patterns
contract EngineeringManager is Salaried, Manager

Key Features: Abstract contracts, virtual/override, multiple inheritance

---

7. ImportsExercise.sol - Library Integration

// External library usage
using SillyStringUtils for string;

Key Features: Library imports, struct returns, external dependencies

---

8. ErrorTriageExercise.sol - Debugging & Error Handling

// Corrected problematic functions
function diffWithNeighbor() // Fixed underflow issues
function applyModifier()    // Fixed type conversion
function popWithReturn()    // Fixed array bounds

Key Features: Bug fixes, type safety, boundary checks

---

9. AddressBook.sol + AddressBookFactory.sol - Factory Pattern

// Factory deployment pattern
function deploy() public returns (address) {
    AddressBook newAddressBook = new AddressBook(msg.sender);
    return address(newAddressBook);
}

Key Features: Factory pattern, Ownable integration, dynamic deployment

---

10. UnburnableToken.sol - Custom Token

// Minimal token with safety checks
function safeTransfer(address _to, uint256 _amount) public

Key Features: Custom token logic, ETH balance validation, claim system

---

11. WeightedVoting.sol - ERC-20 Governance

// Token-weighted voting system
function vote(uint256 _issueId, Vote _vote) public

Key Features: ERC-20 compliance, governance, quorum systems

---

12. HaikuNFT.sol - ERC-721 with Validation

// Unique content NFTs
function mintHaiku(string memory _line1, string memory _line2, string memory _line3)

Key Features: ERC-721 compliance, uniqueness validation, sharing system

🚀 Deployment Scripts

Each contract has a corresponding deployment script in the script/ directory:

Contract	Deploy Script	Purpose
BasicMath	DeployBasicMath.s.sol	Math operations with safety
EmployeeStorage	DeployEmployeeStorage.s.sol	Storage optimization demo
ArraysExercise	DeployArraysExercise.s.sol	Array manipulation
FavoriteRecords	DeployFavoriteRecords.s.sol	Mapping systems
GarageManager	DeployGarageManager.s.sol	Struct management
InheritanceExercise	DeployInheritance.s.sol	Inheritance patterns
ImportsExercise	DeployImportsExercise.s.sol	Library integration
ErrorTriageExercise	DeployErrorTriageExercise.s.sol	Debugging solutions
AddressBookFactory	DeployAddressBookFactory.s.sol	Factory pattern
UnburnableToken	DeployUnburnableToken.s.sol	Custom token
WeightedVoting	DeployWeightedVoting.s.sol	ERC-20 governance
HaikuNFT	DeployHaikuNFT.s.sol	ERC-721 NFTs

Example Deployment

# Deploy to Base Sepolia testnet
forge script script/DeployWeightedVoting.s.sol \
  --rpc-url https://sepolia.base.org \
  --private-key $PRIVATE_KEY \
  --broadcast \
  --verify \
  --etherscan-api-key <YOUR-ETHERSCAN-API>

🔧 Development Workflow

Building Contracts

forge build

Running Tests

forge test
forge test -vvv  # Verbose output

Code Formatting

forge fmt

Gas Analysis

forge snapshot

Local Development

# Start local node
anvil

# Deploy to local node
forge script script/DeployBasicMath.s.sol --rpc-url http://localhost:8545 --private-key <anvil_key> --broadcast

📁 Project Structure

BaseLearn/
├── src/                     # Smart contracts
│   ├── BasicMath.sol
│   ├── EmployeeStorage.sol
│   ├── ArraysExercise.sol
│   ├── FavoriteRecords.sol
│   ├── GarageManager.sol
│   ├── InheritanceExercise.sol
│   ├── ImportsExercise.sol
│   ├── SillyStringUtils.sol
│   ├── ErrorTriageExercise.sol
│   ├── AddressBook.sol
│   ├── AddressBookFactory.sol
│   ├── UnburnableToken.sol
│   ├── WeightedVoting.sol
│   └── HaikuNFT.sol
├── script/                  # Deployment scripts
├── test/                    # Test files
├── lib/                     # Dependencies
└── README.md               # This file

🌟 Key Learning Concepts Covered

• ✅ Gas Optimization: Variable packing, efficient storage patterns
• ✅ Security: Overflow/underflow protection, access controls
• ✅ Design Patterns: Factory, inheritance, library usage
• ✅ Standards: ERC-20, ERC-721 implementations
• ✅ Error Handling: Custom errors, debugging techniques
• ✅ Advanced Features: Governance systems, uniqueness validation

🤝 Contributing

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

📖 Additional Resources

• Base Learn Documentation
• Foundry Book
• Solidity Documentation
• OpenZeppelin Contracts

📄 License

This project is open source (UNLICENSED) - see individual contract files for details.

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Happy Learning! 🎓 This repository represents a journey through Solidity development, from basic concepts to advanced patterns. Each contract builds upon previous knowledge and introduces new concepts essential for blockchain development.