Creating Your Own Libraries

🧑‍💻 Test yourself

1. 📕 What are the differences between Solidity libraries and contracts?
2. 📕 What are the consequences if a library function is not marked as internal?
3. 🧑‍💻 Create a simple library called MathLibrary that contains a function sum to add two uint256 numbers. Then create a function calculateSum inside the fundMe contract that uses the MathLibrary function.

1. What are the differences between Solidity libraries and contracts?

2. What are the consequences if a library function is not marked as internal?

Jika library function tidak ditandai sebagai internal, maka library tidak akan di-embed langsung ke dalam contract saat proses kompilasi. Library tersebut harus di-deploy secara terpisah dan contract utama harus melakukan linking ke alamat library. Hal ini membuat proses deployment lebih kompleks dan eksekusi function dilakukan melalui external call (delegatecall), bukan embedded code.

3. Create a simple library called MathLibrary that contains a function sum to add two uint256 numbers. Then create a function calculateSum inside the fundMe contract that uses the MathLibrary function.

MathLibrary.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.18;

library MathLibrary {
    function sum(uint256 a, uint256 b) internal pure returns (uint256) {
        return a + b;
    }
}

FundMe.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.18;

import {MathLibrary} from "./MathLibrary.sol";

contract FundMe {
    using MathLibrary for uint256;

    function calculateSum(uint256 a, uint256 b) public pure returns (uint256) {
        return MathLibrary.sum(a, b);
    }
}