Smart Contract Development with Solidity: A beginner's guide

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Smart Contract Development with Solidity: A beginner's guide Code Africa Conference November 2023

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Idris Olubisi Developer Advocate, Axelar @olanetsoft

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What will you learn in this talk? ● Introduction to blockchain ● What is a smart contract and why use solidity? ● Solidity basics and syntax ● Development tools and testing ● Best practices and security considerations ● Building, compiling and deploying smart contracts

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Do you have any idea what Blockchain is ?

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What is a Blockchain? A blockchain is a digital ledger of transactions, duplicated and distributed across a network of computer systems.

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Blockchain == Smart Contract ?

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"From 1989 to 2001, there were almost no legitimate winners of the high-value game pieces in the McDonald’s Monopoly game" FBI Special Agent Doug Mathews

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Smart Contract

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What is a Smart Contract? A smart contract is a self-executing contract with the terms of the agreement between buyer and seller being directly written into lines of code and can be deployed on the blockchain.

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Blockchain != Smart Contract

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Solidity: Basics and Syntax

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Variables in Solidity // SPDX-License-Identiﬁer: MIT pragma solidity ^0.8.0; contract Example { int public count; // Integer variable bool public isActive; // Boolean variable address public userAddress; // Address variable }

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Functions in Solidity contract Example { uint private storedData; function set(uint x) public { storedData = x; } function get() public view returns (uint) { return storedData; } }

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Data Types in Solidity contract DataTypes { bool public isTrue = false; uint public num = 123; address public userAddress; struct Person { uint id; string name; } Person public person = Person(1, "Alice"); }

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Basic Structure of a Solidity Contract // SPDX-License-Identiﬁer: MIT pragma solidity ^0.8.0; contract SimpleContract { uint public count; function setCount(uint _count) public { count = _count; } function incrementCount() public { count += 1; } }

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Development Tools and Testing

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Integrated Development Environments (IDEs) ● Remix ● Chain IDE ● Visual Studio Code

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Development Frameworks ● Hardhat ● Foundry ● Trufﬂe Suite

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Blockchain Networks ● Testnet ● Mainnet

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Automated Testing ● Trufﬂe, Foundry and Hardhat offer frameworks for writing and running automated tests ● Mocha and Chai can be used in conjunction with these frameworks for more advanced testing

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Automated Testing: Type of Test ● Unit tests for individual functions ● Integration tests for contract interactions ● Fuzz test

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Programming Languages for writing Smart Contracts

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Programming Languages for writing Smart Contracts ● Solidity ● Rust ● Vyper ● Cadence ● Cargo

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Security and Best Practices

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Security and Best Practices Common vulnerabilities ● Re-entrancy ● Integer overﬂows/underﬂows ● Access control issues ● Unsafe external calls ● Front-running ● Denial of service

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Security and Best Practices Best practices ● Use tested libraries and frameworks ● Keep contracts simple ● Add revert conditions ● Validate inputs and outputs ● Adhere to check-effects-interactions pattern ● Extensive testing

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Security and Best Practices Avoiding mainnet deployments ● Use Remix to deploy initially ● Deploy to testnets ﬁrst ● Run through multiple test cases ● Upgradeability best for mainnet

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Resources and Communities ● Solidity docs ● OpenZeppelin contracts ● 32 hrs course by Patrick Collins ● LearnWeb3.io ● Alchemy University

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Communities ● Developer DAO ● Web3 Afrika ● Web3Bridge ● LearnWeb3 ● Web3 Ladies