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
About the Author
About the Reviewers


The following two statements are true about D function declarations:

  • Functions can be declared in module scope or as members of an aggregate type

  • There's no need to separate the declaration of a function from its implementation, though it is still possible to do so

We've seen two functions already in the form of main and sayHello, both of which had a void return type. Here's one that takes three unsigned bytes representing red, green, blue, and alpha color components and returns a packed 32-bit RGBA value as a uint.

uint packRGBA(ubyte r, ubyte g, ubyte b, ubyte a = 255) {
  return (r << 24) + (g << 16) + (b << 8) + a;

As you can see, D isn't shaking things up in the world of function declaration syntax. We have a return type, uint, the function name, packRGBA, and a parenthesized parameter list. The last parameter has a default value of 255, so the function can be called with only three arguments instead of four. Both the following are valid:

auto white = packRGBA...