Book Image

Learning D

By : Michael Parker
Book Image

Learning D

By: Michael Parker

Overview of this book

D is a modern programming language that is both powerful and efficient. It combines multiple paradigms in a way that opens up a whole new world of software design. It is used to develop both desktop and web applications, with future targets including mobile, and is available on multiple platforms. It is familiar to anyone with some experience in one or more of the C-family languages. However, hidden in the similarities are several differences that can be surprising when trying to apply common idioms from other languages. When learning D on your own, this can make it more time-consuming to master. In order to make the most of the language and become an idiomatic D programmer, it’s necessary to learn how to think in D. This book familiarizes you with D from the ground up, with a heavy focus on helping you to avoid surprises so that you can take your D knowledge to the next level more quickly and painlessly. Your journey begins with a taste of the language and the basics of compiling D programs with DMD, the reference D compiler developed by Digital Mars, and DUB, a community-developed build utility and package manager. You then set out on an exploration of major language features. This begins with the fundamentals of D, including built-in types, conditionals, loops and all of the basic building-blocks of a D program, followed by an examination of D’s object-oriented programming support. You’ll learn how these features differ from languages you may already be familiar with. Next up are D’s compile-time features, such as Compile-Time Function Evaluation and conditional compilation, then generic programming with templates. After that, you’ll learn the more advanced features of ranges and functional pipeline programming. To enhance your D experience, you are next taken on a tour of the D ecosystem and learn how to make D interact with C. Finally, you get a look at D web development using the vibe.d project and the book closes with some handy advice on where to go next.
Table of Contents (19 chapters)
Learning D
Credits
Foreword
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Type qualifiers – const and immutable


Both const and immutable are type qualifiers. This means that, when applied to any type, they actually create a new type. For example, the following equivalent declarations all create a type that is called const(int).

const int x = 10;
const(int) y = 11;
const z = 12;

In the declaration of z, the compiler will infer the type. For a basic type such as int, it makes no difference which syntax is used. However, we'll see shortly that things can be a bit confusing with derived data types, so you may want to get into the habit of using the syntax in the second line when you need to explicitly specify the type. In the rest of this section, we're going to explore the contracts of both const and immutable, then take a look at how they apply to the types we've seen so far.

The contracts

When you declare a variable as immutable, you are stating unequivocally that it is never, ever going to change throughout the lifetime of the program. This is a very strong contract...