Multiple inheritance in Blockchain / Solidity - Mini Project: Build & Apply

Multiple Inheritance in Blockchain Smart Contracts

📖 Scenario: You are building a simple blockchain smart contract system where different contracts provide different features. You want to combine these features using multiple inheritance.

🎯 Goal: Create two base contracts with specific functions, then create a derived contract that inherits from both and uses their functions.

📋 What You'll Learn

Create two base contracts named Token and Ownable with specified functions

Create a derived contract named MyToken that inherits from both Token and Ownable

Implement a function in MyToken that calls functions from both base contracts

Deploy and test the MyToken contract to show multiple inheritance works

💡 Why This Matters

🌍 Real World

Smart contracts often combine features like token management and ownership control. Multiple inheritance lets developers reuse code and build modular contracts.

💼 Career

Understanding multiple inheritance in Solidity is essential for blockchain developers creating complex decentralized applications with reusable components.

1

Create base contract Token

Write a Solidity contract named Token with a public function totalSupply that returns 1000.

Blockchain / Solidity

// Your code here

Need a hint?

Define a contract named Token. Inside it, add a public pure function totalSupply that returns the number 1000.

2

Create base contract Ownable

Add a new contract named Ownable with a public function owner that returns the address 0x1234567890123456789012345678901234567890.

Blockchain / Solidity

pragma solidity ^0.8.0;

contract Token {
    function totalSupply() public pure returns (uint) {
        return 1000;
    }
}

// Add contract Ownable below
// Your code here

Need a hint?

Create a contract named Ownable. Add a public pure function owner that returns the fixed address 0x1234567890123456789012345678901234567890.

3

Create derived contract MyToken with multiple inheritance

Create a contract named MyToken that inherits from both Token and Ownable. Add a public function info that returns both the total supply and owner address by calling the inherited functions.

Blockchain / Solidity

pragma solidity ^0.8.0;

contract Token {
    function totalSupply() public pure returns (uint) {
        return 1000;
    }
}

contract Ownable {
    function owner() public pure returns (address) {
        return 0x1234567890123456789012345678901234567890;
    }
}

// Create contract MyToken inheriting Token and Ownable
// Add function info() returning totalSupply and owner
// Your code here

Need a hint?

Define MyToken inheriting from Token and Ownable. Add a function info that returns a tuple with totalSupply() and owner().

4

Test the MyToken contract output

Write a simple test function or script that calls info() on MyToken and prints the total supply and owner address separated by a space.

Blockchain / Solidity

pragma solidity ^0.8.0;

contract Token {
    function totalSupply() public pure returns (uint) {
        return 1000;
    }
}

contract Ownable {
    function owner() public pure returns (address) {
        return 0x1234567890123456789012345678901234567890;
    }
}

contract MyToken is Token, Ownable {
    function info() public pure returns (uint, address) {
        return (totalSupply(), owner());
    }
}

// Add a function to test info() and print results
// Your code here

Need a hint?

Create a public function test that calls info(), converts the results to strings, and returns them separated by a space.