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

Derived data types

In this section, we're going to observe D's take on pointers, arrays, strings, and associative arrays. Much of what we'll cover here is very different from other C-family languages.


As in other languages that support them, pointers in D are special variables intended to hold memory addresses. Take a moment to compile and run the following:

int* p;
writeln("p's value is ", p);
writeln("p's type is ", typeid(p));
writeln("p's size is ", p.sizeof);	

First, look at the declaration. It should look very familiar to many C-family programmers. All pointer declarations are default initialized to null, so here the first call to writeln prints "null" as the value. The type of p printed in the second writeln is int*. The last line will print 4 in 32-bit and 8 in 64-bit.

So far so good. Now look at the following line and guess what type b is:

int* a, b;

No, b is not an int, it is an int*. The equivalent C or C++ code would look like this:

int *x, *y;

In D, x would be interpreted as...