Advanced Kotlin (Kotlin for Developers Book 4)

You know how to use Kotlin, but do you know the advanced features? What are the consequences of using variance modifiers? What limitations do they introduce, and how can these be overcome? How does property delegation work? How to use reflection? How to implement a KSP or an annotation processor? How is a Kotlin Compiler Plugin implemented? If you want to know the answers to these questions, this book is for you. About the book This book focuses on the advanced aspects of Kotlin's development. These are often features and tools that developers use daily, even though they don’t know exactly how they work. This book explains them and gives you the knowledge to use these features in your projects. Who this book is for This book is for developers with Kotlin experience who want to learn about its advanced features. Readers are expected to have experience in Kotlin development. All the required knowledge can be discovered in the books Kotlin Essentials and Functional Kotlin. What is covered This book focuses on advanced Kotlin features, including: Generic variance modifiers Interface and property delegation Kotlin Contracts Kotlin and Java interoperability Multiplatform development Using Kotlin/JS Kotlin reflection Annotation Processor Kotlin Symbol Processor Kotlin Compiler Plugins Static Analysis with custom rules Table of Contents Introduction Who is this book for? That will be covered? The structure of the book The Kotlin for Developers series Conventions Code conventions Acknowledgments Generic variance modifiers List variance Consumer variance Function types The Covariant Nothing Object The Covariant Nothing Class Variance modifier limitations UnsafeVariance annotation Variance modifier positions Star projection Summary Exercise: Generic types usage Exercise: Generic Response Exercise: Generic Consumer Interface delegation The delegation pattern Delegation and inheritance Kotlin interface delegation support Wrapper classes The decorator pattern Intersection types Limitations Conflicting elements from parents Summary Exercise: ApplicationScope Property delegation How property delegation works Other getValue and setValue parameters Implementing a custom property delegate Provide a delegate Property delegates in Kotlin stdlib The notNull delegate Exercise: Lateinit delegate The lazy delegate Exercise: Blog Post Properties The observable delegate The vetoable delegate A map as a delegate Review of how variables work Summary Exercise: Mutable lazy delegate Kotlin Contracts The meaning of a contract How many times do we invoke a function from an argument? Implications of the fact that a function has returned a value Using contracts in practice Summary Exercise: Coroutine time measurement Java interoperability Nullable types Kotlin type mapping JVM primitives Collection types Annotation targets Static elements JvmField Using Java accessors in Kotlin JvmName JvmMultifileClass JvmOverloads Unit Function types and function interfaces Tricky names Throws JvmRecord Summary Exercise: Adjust Kotlin for Java usage Using Kotlin Multiplatform Multiplatform module configuration Expect and actual elements Possibilities Multiplatform libraries A multiplatform mobile application Summary Exercise: Multiplatform LocalDateTime JavaScript interoperability Setting up a project Using libraries available for Kotlin/JS Using Kotlin/JS Building and linking a package Distributing a package to npm Exposing objects Exposing Flow and StateFlow Adding npm dependencies Frameworks and libraries for Kotlin/JS JavaScript and Kotlin/JS limitations Summary Exercise: Migrating a Kotlin/JVM project to KMP Reflection Hierarchy of classes Function references Parameter references Property references Class reference Serialization example Referencing types Type reflection example: Random value Kotlin and Java reflection Breaking encapsulation Summary Exercise: Function caller Exercise: Object serialization to JSON Exercise: Object serialization to XML Exercise: DSL-based dependency injection library Annotation processing Your first annotation processor Hiding generated classes Summary Exercise: Annotation Processing Kotlin Symbol Processing Your first KSP processor Testing KSP Dependencies and incremental processing Multiple rounds processing Using KSP on multiplatform projects Summary Exercise: Kotlin Symbol Processing Kotlin Compiler Plugins Compiler frontend and backend Compiler extensions Popular compiler plugins Making all classes open Changing a type Generate function wrappers Example plugin implementations Summary Static Code Analysers What are Static Analysers? Types of analysers Kotlin Code Analysers Setting up detekt Writing your first detekt Rule Conclusion Ending Exercise solutions