Book Image

Crystal Programming

By : George Dietrich, Guilherme Bernal
Book Image

Crystal Programming

By: George Dietrich, Guilherme Bernal

Overview of this book

Crystal is a programming language with a concise and user-friendly syntax, along with a seamless system and a performant core, reaching C-like speed. This book will help you gain a deep understanding of the fundamental concepts of Crystal and show you how to apply them to create various types of applications. This book comes packed with step-by-step explanations of essential concepts and practical examples. You'll learn how to use Crystal’s features to create complex and organized projects relying on OOP and its most common design patterns. As you progress, you'll gain a solid understanding of both the basic and advanced features of Crystal. This will enable you to build any application, including command-line interface (CLI) programs and web applications using IOs, concurrency and C bindings, HTTP servers, and the JSON API. By the end of this programming book, you’ll be equipped with the skills you need to use Crystal programming for building and understanding any application you come across.
Table of Contents (26 chapters)
1
Part 1: Getting Started
5
Part 2: Learning by Doing – CLI
10
Part 3: Learn by Doing – Web Application
13
Part 4: Metaprogramming
18
Part 5: Supporting Tools

Chapter 12: Leveraging Compile-Time Type Introspection

In the previous chapters, we have mainly been using macros within types and methods themselves in order to access compile-time information or read annotations. However, this greatly reduces the effectiveness of macros to be able to dynamically react as new types are added or annotated. The next Crystal metaprogramming concept that we are going to take a look at is that of compile-time type introspection, which will cover the following topics:

  • Iterating type variables
  • Iterating types
  • Iterating methods

By the end of this chapter, you should be able to create macros that generate code using instance variables, methods, and/or type information along with data read off of annotations.