Book Image

Solidity Programming Essentials

Book Image

Solidity Programming Essentials

Overview of this book

Solidity is a contract-oriented language whose syntax is highly influenced by JavaScript, and is designed to compile code for the Ethereum Virtual Machine. Solidity Programming Essentials will be your guide to understanding Solidity programming to build smart contracts for Ethereum and blockchain from ground-up. We begin with a brief run-through of blockchain, Ethereum, and their most important concepts or components. You will learn how to install all the necessary tools to write, test, and debug Solidity contracts on Ethereum. Then, you will explore the layout of a Solidity source file and work with the different data types. The next set of recipes will help you work with operators, control structures, and data structures while building your smart contracts. We take you through function calls, return types, function modifers, and recipes in object-oriented programming with Solidity. Learn all you can on event logging and exception handling, as well as testing and debugging smart contracts. By the end of this book, you will be able to write, deploy, and test smart contracts in Ethereum. This book will bring forth the essence of writing contracts using Solidity and also help you develop Solidity skills in no time.
Table of Contents (17 chapters)
Title Page
Copyright and Credits
Packt Upsell
Contributors
Preface
Index

Modifiers


Modifiers are another concept unique to Solidity. Modifiers help in modifying the behavior of a function. Let's try to understand this with the help of an example. The following code  does not use modifiers; in this contract, two state variables, two functions, and a constructor are defined. One of the state variables stores the address of the account deploying the contract. Within the constructor, the global variable msg.sender is used to input the account value in the owner state variable. The two functions check whether the caller is the same as the account that deployed the contract; if it is, the function code is executed, otherwise it ignores the rest of the code. While this code works as is, it can be made better both in terms of readability and manageability. This is where modifiers can help. In this example, the checks are made using the if conditional statements. Later, in the next chapter, we will see how to use new Solidity constructs, such as require and assert, to...