Extending kotlin-inject for fun & profit

Kotlin-inject is a dependency injection framework for Kotlin Multiplatform. It verifies the dependency graph during compilaton and generates the necessary code to instantiate the object graph at runtime. It offers a similar feature set as Dagger 2 without the limitation of being tied to the JVM and Android only.

This talk will offer a short introduction to kotlin-inject and discuss its benefits and downsides and how the framework scales in large, modularized code bases. To close some of the gaps and solve project specific use cases KSP and custom code generators will be used to extend the framework and to give us features similar to the ones Anvil provides for Dagger 2. These practical examples serve as an introduction and blueprint into the meta-programming world to reduce boilerplate and simplify patterns in your code base.

Transcript

1. Extending kotlin-inject for fun & profit June 6th, 2024 Ralf Wondratschek
2. https://www.youtube.com/watch?v=xESX82kwjn4
4. https://www.youtube.com/watch?v=0T_zvUEqsD4
5. Background https://ralf-wondratschek.com/presentations
6. Background • We like Dagger 2 for its many benefits • We like Anvil for its simplicity • But both don’t work with KMP in common code
7. Dagger 2 Provider side Component Injection side
8. interface WeatherRepository { fun provideForecast(location: Location): Forecast } Dagger 2
9. Dagger 2 interface WeatherRepository { fun provideForecast(location: Location): Forecast } class WeatherRepositoryImpl( client: HttpClient, ) : WeatherRepository { ... }
10. Dagger 2 interface WeatherRepository { fun provideForecast(location: Location): Forecast } class WeatherRepositoryImpl( client: HttpClient, ) : WeatherRepository { ... } @Module object WeatherRepositoryModule { @Provides @Singleton fun provideWeatherRepository(client: HttpClient): WeatherRepository { return WeatherRepositoryImpl(client) } }
11. Dagger 2 interface WeatherRepository { fun provideForecast(location: Location): Forecast } class WeatherRepositoryImpl( client: HttpClient, ) : WeatherRepository { ... } @Module object WeatherRepositoryModule { @Provides @Singleton fun provideWeatherRepository(client: HttpClient): WeatherRepository { return WeatherRepositoryImpl(client) } }
12. Dagger 2 interface WeatherRepository { fun provideForecast(location: Location): Forecast } class WeatherRepositoryImpl( client: HttpClient, ) : WeatherRepository { ... } @Module object WeatherRepositoryModule { @Provides @Singleton fun provideWeatherRepository(client: HttpClient): WeatherRepository { return WeatherRepositoryImpl(client) } }
13. Dagger 2 @Singleton @Component( modules = [ WeatherRepositoryModule::class, ] ) interface AppComponent
14. Dagger 2 @Singleton @Component( modules = [ WeatherRepositoryModule::class, ] ) interface AppComponent
15. @Component( modules = [ WeatherRepositoryModule::class, ] ) interface AppComponent Dagger 2
16. Dagger 2 @Singleton @Component( modules = [ WeatherRepositoryModule::class, ] ) interface AppComponent
17. Dagger 2 @Singleton @Component( modules = [ WeatherRepositoryModule::class, ] ) interface AppComponent val appComponent = DaggerAppComponent.create()
18. Dagger 2 @Singleton @Component( modules = [ WeatherRepositoryModule::class, ] ) interface AppComponent { fun weatherRepository(): WeatherRepository } val appComponent = DaggerAppComponent.create() val weatherRepository = appComponent.weatherRepository()
19. Dagger 2 @Singleton @Component( modules = [ WeatherRepositoryModule::class, ] ) interface AppComponent { fun weatherRepository(): WeatherRepository } val appComponent = DaggerAppComponent.create() val weatherRepository = appComponent.weatherRepository()
20. Dagger 2 class WeatherRepositoryImpl( client: HttpClient, ) : WeatherRepository { ... } @Module object WeatherRepositoryModule { @Provides @Singleton fun provideWeatherRepository(client: HttpClient): WeatherRepository { return WeatherRepositoryImpl(client) } }
21. Dagger 2 @Singleton class WeatherRepositoryImpl @Inject constructor( client: HttpClient, ) : WeatherRepository @Module object WeatherRepositoryModule { @Provides @Singleton fun provideWeatherRepository(client: HttpClient): WeatherRepository { return WeatherRepositoryImpl(client) } }
22. Dagger 2 @Singleton class WeatherRepositoryImpl @Inject constructor( client: HttpClient, ) : WeatherRepository @Module object WeatherRepositoryModule { @Provides @Singleton fun provideWeatherRepository(client: HttpClient): WeatherRepository { return WeatherRepositoryImpl(client) } }
23. Dagger 2 @Singleton class WeatherRepositoryImpl @Inject constructor( client: HttpClient, ) : WeatherRepository @Module interface WeatherRepositoryModule { @Binds fun bindWeatherRepository( weatherRepositoryImpl: WeatherRepositoryImpl ): WeatherRepository }
24. Dagger 2 :app AppComponent :weather WeatherRepositoryModule
25. Dagger 2 :app AppComponent :weather WeatherRepositoryModule :forecast appComponent.weatherRepository()
26. Dagger 2 :app AppComponent :weather WeatherRepositoryModule :forecast appComponent.weatherRepository()
27. Dagger 2 @Singleton @Component( modules = [ WeatherRepositoryModule::class, ] ) interface AppComponent { fun weatherRepository(): WeatherRepository }
28. Dagger 2 interface WeatherComponent { fun weatherRepository(): WeatherRepository } @Singleton @Component( modules = [ WeatherRepositoryModule::class, ] ) interface AppComponent : WeatherComponent
29. Dagger 2 :app AppComponent :weather WeatherRepositoryModule :forecast appComponent.weatherRepository()
30. Dagger 2 :app AppComponent :weather WeatherRepositoryModule :forecast WeatherComponent
31. Anvil
32. Anvil https://ralf-wondratschek.com/presentations
33. Anvil object AppScope @Contributes*(AppScope::class) @MergeComponent(AppScope::class)
34. Dagger 2 @Singleton class WeatherRepositoryImpl @Inject constructor( client: HttpClient, ) : WeatherRepository @Module interface WeatherRepositoryModule { @Binds fun bindWeatherRepository( weatherRepositoryImpl: WeatherRepositoryImpl ): WeatherRepository }
35. Anvil @Singleton class WeatherRepositoryImpl @Inject constructor( client: HttpClient, ) : WeatherRepository @Module @ContributesTo(AppScope::class) interface WeatherRepositoryModule { @Binds fun bindWeatherRepository( weatherRepositoryImpl: WeatherRepositoryImpl ): WeatherRepository }
36. Anvil @Singleton @ContributesBinding(AppScope::class) class WeatherRepositoryImpl @Inject constructor( client: HttpClient, ) : WeatherRepository @Module @ContributesTo(AppScope::class) interface WeatherRepositoryModule { @Binds fun bindWeatherRepository( weatherRepositoryImpl: WeatherRepositoryImpl ): WeatherRepository }
37. Anvil @Singleton @ContributesBinding(AppScope::class) class WeatherRepositoryImpl @Inject constructor( client: HttpClient, ) : WeatherRepository
38. Dagger 2 interface WeatherComponent { fun weatherRepository(): WeatherRepository }
39. Anvil @ContributesTo(AppScope::class) interface WeatherComponent { fun weatherRepository(): WeatherRepository }
40. Dagger 2 @Singleton @Component( modules = [ WeatherRepositoryModule::class, ] ) interface AppComponent : WeatherComponent
41. Anvil @Singleton @MergeComponent( scope = AppScope::class, modules = [ WeatherRepositoryModule::class, ] ) interface AppComponent : WeatherComponent
42. Anvil @Singleton @MergeComponent( scope = AppScope::class, ) interface AppComponent : WeatherComponent
43. Anvil @Singleton @MergeComponent(AppScope::class) interface AppComponent : WeatherComponent
44. Anvil @Singleton @MergeComponent(AppScope::class) interface AppComponent
45. Anvil - Other benefits • Removes boilerplate • Improves build times significantly • Easy to replace bindings in tests • Extensible with custom code generators
46. kotlin-inject
47. “The Dagger 2 for Kotlin Multiplatform.”
48. kotlin-inject • Compile-time dependency injection framework for Kotlin • Architecture very similar to Dagger 2 • Similar feature set as Dagger 2: Provider methods, components, scopes, qualifiers, multi-bindings, assisted injection, lazy injection, … • Unique features: KMP support, uses KSP, no modules, no binding methods, override provider functions, function support, default arguments, …
49. kotlin-inject import me.tatarka.inject.annotations.* @Scope annotation class Singleton
50. Dagger 2 @Singleton class WeatherRepositoryImpl @Inject constructor( client: HttpClient, ) : WeatherRepository @Module interface WeatherRepositoryModule { @Binds fun bindWeatherRepository( weatherRepositoryImpl: WeatherRepositoryImpl ): WeatherRepository }
51. kotlin-inject @Singleton @Inject class WeatherRepositoryImpl( client: HttpClient, ) : WeatherRepository @Module interface WeatherRepositoryModule { @Binds fun bindWeatherRepository( weatherRepositoryImpl: WeatherRepositoryImpl ): WeatherRepository }
52. kotlin-inject @Singleton @Inject class WeatherRepositoryImpl( client: HttpClient, ) : WeatherRepository @Module interface WeatherRepositoryModule { @Binds fun bindWeatherRepository( weatherRepositoryImpl: WeatherRepositoryImpl ): WeatherRepository }
53. kotlin-inject @Singleton @Inject class WeatherRepositoryImpl( client: HttpClient, ) : WeatherRepository interface WeatherRepositoryComponent { @Provides fun provideWeatherRepository( weatherRepository: WeatherRepositoryImpl ): WeatherRepository = weatherRepository }
54. kotlin-inject @Provides fun provideWeatherRepository( weatherRepository: WeatherRepositoryImpl ): WeatherRepository = weatherRepository val WeatherRepositoryImpl.bind: WeatherRepository @Provides get() = this
55. Dagger 2 @Singleton @Component( modules = [ WeatherRepositoryModule::class, ] ) interface AppComponent val appComponent = DaggerAppComponent.create()
56. kotlin-inject @Singleton @Component interface AppComponent : WeatherRepositoryComponent val appComponent = DaggerAppComponent.create()
57. kotlin-inject @Singleton @Component interface AppComponent : WeatherRepositoryComponent val appComponent = DaggerAppComponent.create()
58. kotlin-inject @Singleton @Component interface AppComponent : WeatherRepositoryComponent val appComponent = AppComponent::class.create()
59. kotlin-inject @Singleton @Component interface AppComponent : WeatherRepositoryComponent { val weatherRepository: WeatherRepository } val appComponent = AppComponent::class.create() val weatherRepository = appComponent.weatherRepository
60. kotlin-inject @Singleton @Component interface AppComponent : WeatherRepositoryComponent { val weatherRepository: WeatherRepository }
61. kotlin-inject interface WeatherComponent { val weatherRepository: WeatherRepository } @Singleton @Component interface AppComponent : WeatherRepositoryComponent, WeatherComponent
62. kotlin-inject :app AppComponent :weather WeatherRepositoryComponent :forecast WeatherComponent
63. kotlin-inject - the good Reduced API surface: Member injection @Binds @BindsInstance @Module @Subcomponent @Assisted @AssistedInject
64. kotlin-inject - the good Arguments: @Component abstract class AppComponent val appComponent = AppComponent::class.create()
65. kotlin-inject - the good Arguments: @Component abstract class AppComponent( @get:Provides val application: Application, ) val application = … val appComponent = AppComponent::class.create(application)
66. kotlin-inject - the good Component inheritance: @Component abstract class AppComponent @Component abstract class LoggedInComponent( @get:Provides val user: User, )
67. kotlin-inject - the good Component inheritance: @Component abstract class AppComponent @Component abstract class LoggedInComponent( @Component val appComponent: AppComponent, @get:Provides val user: User, )
68. kotlin-inject - the good Component inheritance: @Component abstract class AppComponent @Component abstract class LoggedInComponent( @Component val appComponent: AppComponent, @get:Provides val user: User, ) LoggedInComponent::class.create(appComponent, user)
69. kotlin-inject - the good Override functions @Component abstract class AppComponent @Component abstract class LoggedInComponent(...)
70. kotlin-inject - the good Override functions @Component abstract class AppComponent @Component abstract class LoggedInComponent(...) { interface Factory { fun loggedInComponent(user: User): LoggedInComponent } }
71. kotlin-inject - the good Override functions @Component abstract class AppComponent : LoggedInComponent.Factory { override fun loggedInComponent(user: User): LoggedInComponent { return LoggedInComponent::class.create(this, user) } } @Component abstract class LoggedInComponent(...) { interface Factory { fun loggedInComponent(user: User): LoggedInComponent } }
72. kotlin-inject - the good Kotlin support Lazy, default arguments, assisted injection, overridden functions, …
73. kotlin-inject - the good Kotlin support Lazy, default arguments, assisted injection, overridden functions, … val viewModels: Map<Class<out ViewModel>, @JvmSuppressWildcards Provider<ViewModel>>
74. kotlin-inject - the good Kotlin support Lazy, default arguments, assisted injection, overridden functions, … val viewModels: Map<Class<out ViewModel>, @JvmSuppressWildcards Provider<ViewModel>>
75. kotlin-inject - the good KAPT Stub generation (kotlinc)
76. kotlin-inject - the good KAPT Stub generation (kotlinc) KAPT
77. kotlin-inject - the good KAPT Stub generation (kotlinc) KAPT kotlinc
78. kotlin-inject - the good KAPT Stub generation (kotlinc) KAPT kotlinc javac
79. kotlin-inject - the good KSP KSP (kotlinc)
80. kotlin-inject - the good KSP KSP (kotlinc) kotlinc
81. kotlin-inject - the bad
82. kotlin-inject - the bad Scopes object AppScope object LoggedInScope @SingleIn(AppScope::class) @SingleIn(LoggedInScope::class)
83. kotlin-inject - the bad Scopes @SingleInAppScope @SingleInLoggedInScope … https://github.com/evant/kotlin-inject/issues/377
84. kotlin-inject - the bad Qualifiers @ForScope(AppScope::class) @ForScope(LoggedInScope::class)
85. kotlin-inject - the bad Qualifiers typealias AppScopeCoroutineScope = CoroutineScope typealias LoggedInScopeCoroutineScope = CoroutineScope typealias PresenterCoroutineScope = CoroutineScope … https://github.com/evant/kotlin-inject/issues/253
86. kotlin-inject - the bad No wide adoption
87. kotlin-inject - best practices :app1 AppComponent, LoggedInComponent :weather WeatherRepositoryModule :forecast WeatherComponent
88. kotlin-inject - best practices :app1 AppComponent, LoggedInComponent :weather WeatherRepositoryModule :forecast WeatherComponent :app2 AppComponent, LoggedInComponent
89. kotlin-inject - best practices :app1 AppComponent, LoggedInComponent :weather WeatherRepositoryModule :forecast WeatherComponent :app2 AppComponent, LoggedInComponent :app3 AppComponent, LoggedInComponent
90. kotlin-inject - best practices Scopes: @Inject @Singleton class WeatherRepositoryImpl( client: HttpClient, ) : WeatherRepository
91. kotlin-inject - best practices Naming: interface WeatherRepositoryComponent { val weatherRepository: WeatherRepository @Provides fun provideWeatherRepository( weatherRepository: WeatherRepositoryImpl ): WeatherRepository = weatherRepository }
92. kotlin-inject - best practices Naming: interface ${descriptiveName}Component { val weatherRepository: WeatherRepository @Provides fun provide${returnType}( weatherRepository: WeatherRepositoryImpl ): WeatherRepository = weatherRepository }
93. kotlin-inject - best practices Naming: interface ${descriptiveName}Component { val weatherRepository: WeatherRepository @Provides fun provide${returnType}( weatherRepository: WeatherRepositoryImpl ): WeatherRepository = weatherRepository }
94. kotlin-inject - best practices Component interfaces as inner classes: abstract class ViewRenderer<T : BaseModel> : Renderer<T> { fun init(...) { val coroutineScope = CoroutineScope( rootScopeProvider.rootScope.diComponent<Component>().dispatcher + Job(), ) } interface Component { val dispatcher: MainCoroutineDispatcher } }
95. kotlin-inject - best practices Component interfaces as inner classes: abstract class ViewRenderer<T : BaseModel> : Renderer<T> { fun init(...) { val coroutineScope = CoroutineScope( rootScopeProvider.rootScope.diComponent<Component>().dispatcher + Job(), ) } interface Component { val dispatcher: MainCoroutineDispatcher } }
96. kotlin-inject - best practices Component per platform @Component abstract class AndroidAppComponent( @get:Provides val application: Application, ) : LoggedInComponent.Factory { override fun loggedInComponent(user: User): LoggedInComponent { return AndroidLoggedInComponent::class.create(this, user) } }
97. kotlin-inject - best practices Component per platform @Component abstract class AndroidAppComponent( @get:Provides val application: Application, ) : LoggedInComponent.Factory { override fun loggedInComponent(user: User): LoggedInComponent { return AndroidLoggedInComponent::class.create(this, user) } }
98. kotlin-inject - best practices Component per platform @Component abstract class IosAppComponent( @get:Provides val uiApplication: UIApplication, ) : LoggedInComponent.Factory { override fun loggedInComponent(user: User): LoggedInComponent { return IosLoggedInComponent::class.create(this, user) } }
99. kotlin-inject - best practices Component per platform @Component abstract class IosAppComponent( @get:Provides val uiApplication: UIApplication, ) : LoggedInComponent.Factory { override fun loggedInComponent(user: User): LoggedInComponent { return IosLoggedInComponent::class.create(this, user) } }
100. kotlin-inject - best practices Component per platform @Component abstract class DesktopAppComponent : LoggedInComponent.Factory { override fun loggedInComponent(user: User): LoggedInComponent { return DesktopLoggedInComponent::class.create(this, user) } }
101. kotlin-inject - best practices Component per platform interface LoggedInComponent( val appComponent: AppComponent val user: User ) @Component abstract class AndroidLoggedInComponent( @Component override val appComponent: AndroidAppComponent, @get:Provides override val user: User, ) : LoggedInComponent
102. kotlin-inject - best practices iOS @Component abstract class IosAppComponent( @get:Provides val iosNativeImplementations: IosNativeImplementations, ) : IosNativeImplementations.Component
103. kotlin-inject - best practices iOS interface IosNativeImplementations { val uiApplication: UIApplication interface Component { @Provides fun provideUiApplication( iosNativeImplementations: IosNativeImplementations ): UIApplication = iosNativeImplementations.uiApplication } }
104. kotlin-inject - boilerplate @Component abstract class AppComponent(...)
105. kotlin-inject - boilerplate @Component abstract class AppComponent(...) : Component1
106. kotlin-inject - boilerplate @Component abstract class AppComponent(...) : Component1, Component2
107. kotlin-inject - boilerplate @Component abstract class AppComponent(...) : Component1, Component2, Component3
108. kotlin-inject - boilerplate @Component abstract class AppComponent(...) : Component1, Component2, Component3, Component4
109. kotlin-inject - boilerplate @Component abstract class AppComponent(...) : Component1, Component2, Component3, Component4, Component5
110. kotlin-inject - boilerplate @Component abstract class AppComponent(...) : Component1, Component2, Component3, Component4, Component5, Component6
111. kotlin-inject - boilerplate @Component abstract class AppComponent(...) : Component1, Component2, Component3, Component4, Component5, Component6, Component7
112. kotlin-inject - boilerplate @Component abstract class AppComponent(...) : Component1, Component2, Component3, Component4, Component5, Component6, Component7, Component8
113. kotlin-inject - boilerplate @Component abstract class AppComponent(...) : Component1, Component2, Component3, Component4, Component5, Component6, Component7, Component8, Component9
114. kotlin-inject - boilerplate @Component abstract class AppComponent(...) : Component1, Component2, Component3, Component4, Component5, Component6, Component7, Component8, Component9, …
115. kotlin-inject - boilerplate interface NewComponent { … }
116. kotlin-inject - boilerplate interface NewComponent { … } @Component abstract class AndroidApp1Component : NewComponent
117. kotlin-inject - boilerplate interface NewComponent { … } @Component abstract class AndroidApp1Component : NewComponent @Component abstract class AndroidApp2Component : NewComponent
118. kotlin-inject - boilerplate interface NewComponent { … } @Component abstract class AndroidApp1Component : NewComponent @Component abstract class AndroidApp2Component : NewComponent @Component abstract class DemoAppComponent : NewComponent
119. kotlin-inject - boilerplate interface NewComponent { … } @Component abstract class AndroidApp1Component : NewComponent @Component abstract class AndroidApp2Component : NewComponent @Component abstract class DemoAppComponent : NewComponent @Component abstract class IosAppComponent : NewComponent
120. kotlin-inject - boilerplate interface NewComponent { … } @Component abstract class AndroidApp1Component : NewComponent @Component abstract class AndroidApp2Component : NewComponent @Component abstract class DemoAppComponent : NewComponent @Component abstract class IosAppComponent : NewComponent @Component abstract class DesktopAppComponent : NewComponent …
121. kotlin-inject - boilerplate @Provides fun provideWeatherRepository( weatherRepository: WeatherRepositoryImpl ): WeatherRepository = weatherRepository
122. kotlin-inject - boilerplate We really miss Anvil …
123. KSP • Supports KMP • Supports multiple rounds https://kotlinlang.org/docs/ksp-overview.html
124. KSP include ':runtime' include ':compiler'
125. KSP // runtime/build.gradle plugins { id 'org.jetbrains.kotlin.multiplatform' } // runtime/src/commonMain/kotlin/…/YourAnnotation.kt annotation class YourAnnotation
126. KSP // compiler/build.gradle plugins { id 'org.jetbrains.kotlin.jvm' } dependencies { implementation "com.google.devtools.ksp:symbol-processing-api:$ksp_version" implementation "com.squareup:kotlinpoet:$kotlin_poet_version" implementation "com.squareup:kotlinpoet-ksp:$kotlin_poet_version" testImplementation "dev.zacsweers.kctfork:core:$kotlin_compile_testing_version" testImplementation "dev.zacsweers.kctfork:ksp:$kotlin_compile_testing_version" }
127. KSP // compiler/src/main/kotlin/…/YourSymbolProcessorProvider.kt @AutoService(SymbolProcessorProvider::class) class YourSymbolProcessorProvider : SymbolProcessorProvider { override fun create(environment: SymbolProcessorEnvironment): SymbolProcessor { return ... } }
128. KSP // compiler/src/main/kotlin/…/YourSymbolProcessor.kt private class YourSymbolProcessor( private val environment: SymbolProcessorEnvironment, ) : SymbolProcessor { override fun process(resolver: Resolver): List<KSAnnotated> { return emptyList() } }
129. KSP environment.logger.error(message, symbol)
130. KSP environment.logger.error(message, symbol) > SourceFile.kt:8: Contributed component interfaces must be public.
131. kotlin-inject - Anvil @Target(CLASS) annotation class ContributesTo @Target(CLASS) annotation class MergeComponent
132. kotlin-inject - Anvil • Use the scope as connection between contribution and merging side • Find all contributions for a scope
133. kotlin-inject - Anvil interface WeatherComponent { val weatherRepository: WeatherRepository } @Singleton @Component interface AppComponent : WeatherComponent
134. kotlin-inject - Anvil interface WeatherComponent { val weatherRepository: WeatherRepository }
135. kotlin-inject - Anvil @ContributesTo interface WeatherComponent { val weatherRepository: WeatherRepository }
136. kotlin-inject - Anvil @ContributesTo @Singleton interface WeatherComponent { val weatherRepository: WeatherRepository }
137. kotlin-inject - Anvil @Singleton @Component interface AppComponent
138. kotlin-inject - Anvil @Singleton @Component @MergeComponent interface AppComponent
139. kotlin-inject - Anvil @Singleton @Component @MergeComponent interface AppComponent : AppComponentMerged
140. kotlin-inject - Anvil private class MergeComponentProcessor : SymbolProcessor { override fun process(resolver: Resolver): List<KSAnnotated> { val declarations = resolver.getDeclarationsFromPackage(…) ... } }
141. kotlin-inject - Anvil private class MergeComponentProcessor : SymbolProcessor { override fun process(resolver: Resolver): List<KSAnnotated> { val declarations = resolver.getDeclarationsFromPackage(…) ... } }
142. kotlin-inject - Anvil @ContributesTo interface Component1
143. kotlin-inject - Anvil @ContributesTo interface Component1 @ContributesTo interface Component2
144. kotlin-inject - Anvil @ContributesTo interface Component1 @ContributesTo interface Component2 @MergeComponent interface AppComponent
145. kotlin-inject - Anvil @ContributesTo interface Component1 @ContributesTo interface Component2 @MergeComponent interface AppComponent interface AppComponentMerged : Component1, Component2
146. kotlin-inject - Anvil @ContributesTo interface Component1 @ContributesTo interface Component2 @MergeComponent interface AppComponent interface AppComponentMerged : Component1, Component2 @MergeComponent interface AppComponent : AppComponentMerged
147. kotlin-inject - Anvil @ContributesTo interface Component1 @ContributesTo interface Component2 @MergeComponent interface AppComponent interface AppComponentMerged : Component1, Component2 @MergeComponent interface AppComponent : AppComponentMerged Run kotlin-inject processor
148. @ContributesTo // Given package com.amazon @ContributesTo @Singleton interface WeatherComponent { val weatherRepository: WeatherRepository }
149. @ContributesTo // Given package com.amazon @ContributesTo @Singleton interface WeatherComponent { val weatherRepository: WeatherRepository } // Generate package anvil.lookup @Singleton interface ComAmazonWeatherComponent : WeatherComponent
150. @ContributesTo // Given package com.amazon @ContributesTo @Singleton interface WeatherComponent { val weatherRepository: WeatherRepository } // Generate package anvil.lookup @Singleton interface ComAmazonWeatherComponent : WeatherComponent
151. @ContributesTo // Given package com.amazon @ContributesTo @Singleton interface WeatherComponent { val weatherRepository: WeatherRepository } // Generate package anvil.lookup @Singleton interface ComAmazonWeatherComponent : WeatherComponent
152. @ContributesTo resolver .getNewSymbolsWithAnnotation(ContributesTo::class) .filterIsInstance<KSClassDeclaration>() .onEach { checkIsInterface(it) checkIsPublic(it) } .forEach { generateComponentInterface(it) }
153. @ContributesTo fun Resolver.getNewSymbolsWithAnnotation(annotation: KClass<*>): Sequence<KSAnnotated> { val newFiles = getNewFiles().toSet() return getSymbolsWithAnnotation(annotation) .filter { it.containingFile in newFiles } }
154. @ContributesTo private fun generateComponentInterface(clazz: KSClassDeclaration) { val componentClassName = ClassName(LOOKUP_PACKAGE, clazz.safeClassName) val scope = clazz.scope() val fileSpec = FileSpec.builder(componentClassName) .addType( TypeSpec .interfaceBuilder(componentClassName) .addOriginatingKSFile(clazz.requireContainingFile()) .addAnnotation(scope.toAnnotationSpec()) .addSuperinterface(clazz.toClassName()) .build(), ) .build() fileSpec.writeTo(codeGenerator, aggregating = false) }
155. @ContributesTo private fun generateComponentInterface(clazz: KSClassDeclaration) { val componentClassName = ClassName(LOOKUP_PACKAGE, clazz.safeClassName) val scope = clazz.scope() val fileSpec = FileSpec.builder(componentClassName) .addType( TypeSpec .interfaceBuilder(componentClassName) .addOriginatingKSFile(clazz.requireContainingFile()) .addAnnotation(scope.toAnnotationSpec()) .addSuperinterface(clazz.toClassName()) .build(), ) .build() fileSpec.writeTo(codeGenerator, aggregating = false) }
156. @ContributesTo private fun generateComponentInterface(clazz: KSClassDeclaration) { val componentClassName = ClassName(LOOKUP_PACKAGE, clazz.safeClassName) val scope = clazz.scope() val fileSpec = FileSpec.builder(componentClassName) .addType( TypeSpec .interfaceBuilder(componentClassName) .addOriginatingKSFile(clazz.requireContainingFile()) .addAnnotation(scope.toAnnotationSpec()) .addSuperinterface(clazz.toClassName()) .build(), ) .build() fileSpec.writeTo(codeGenerator, aggregating = false) }
157. @ContributesTo private fun generateComponentInterface(clazz: KSClassDeclaration) { val componentClassName = ClassName(LOOKUP_PACKAGE, clazz.safeClassName) val scope = clazz.scope() val fileSpec = FileSpec.builder(componentClassName) .addType( TypeSpec .interfaceBuilder(componentClassName) .addOriginatingKSFile(clazz.requireContainingFile()) .addAnnotation(scope.toAnnotationSpec()) .addSuperinterface(clazz.toClassName()) .build(), ) .build() fileSpec.writeTo(codeGenerator, aggregating = false) }
158. @ContributesTo private fun generateComponentInterface(clazz: KSClassDeclaration) { val componentClassName = ClassName(LOOKUP_PACKAGE, clazz.safeClassName) val scope = clazz.scope() val fileSpec = FileSpec.builder(componentClassName) .addType( TypeSpec .interfaceBuilder(componentClassName) .addOriginatingKSFile(clazz.requireContainingFile()) .addAnnotation(scope.toAnnotationSpec()) .addSuperinterface(clazz.toClassName()) .build(), ) .build() fileSpec.writeTo(codeGenerator, aggregating = false) }
159. @ContributesTo @Test fun `a component interface is generated in the lookup package for a contributed component interface`() { compile( """ package com.amazon.test import com.amazon.ContributesTo import com.amazon.Singleton @ContributesTo @Singleton interface ComponentInterface """, ) { val generatedComponent = componentInterface.generatedComponent assertThat(generatedComponent.packageName).isEqualTo(LOOKUP_PACKAGE) assertThat(generatedComponent.interfaces).containsExactly(componentInterface) assertThat(generatedComponent).isAnnotatedWith(Singleton::class) } } https://github.com/square/anvil/blob/main/compiler-utils/src/testFixtures/java/com/squareup/anvil/compiler/internal/testing/AnvilCompilation.kt
160. @ContributesTo val generatedComponent = componentInterface.generatedComponent internal val JvmCompilationResult.componentInterface: Class<*> get() = classLoader.loadClass("com.amazon.test.ComponentInterface") internal val Class<*>.generatedComponent: Class<*> get() = classLoader.loadClass( "$LOOKUP_PACKAGE." + canonicalName.split(".").joinToString(separator = "") { it.capitalize() }, )
161. @ContributesTo val generatedComponent = componentInterface.generatedComponent internal val JvmCompilationResult.componentInterface: Class<*> get() = classLoader.loadClass("com.amazon.test.ComponentInterface") internal val Class<*>.generatedComponent: Class<*> get() = classLoader.loadClass( "$LOOKUP_PACKAGE." + canonicalName.split(".").joinToString(separator = "") { it.capitalize() }, )
162. @ContributesTo val generatedComponent = componentInterface.generatedComponent internal val JvmCompilationResult.componentInterface: Class<*> get() = classLoader.loadClass("com.amazon.test.ComponentInterface") internal val Class<*>.generatedComponent: Class<*> get() = classLoader.loadClass( "$LOOKUP_PACKAGE." + canonicalName.split(".").joinToString(separator = "") { it.capitalize() }, )
163. @MergeComponent // Given package com.amazon @Singleton @Component @MergeComponent interface AppComponent : AppComponentMerged
164. @MergeComponent // Given package com.amazon @Singleton @Component @MergeComponent interface AppComponent : AppComponentMerged // Generate package com.amazon @Singleton interface AppComponentMerged : ${contributedSuperTypes}
165. @MergeComponent // Given package com.amazon @Singleton @Component @MergeComponent interface AppComponent : AppComponentMerged // Generate package com.amazon @Singleton interface AppComponentMerged : ${contributedSuperTypes}
166. @MergeComponent // Given package com.amazon @Singleton @Component @MergeComponent interface AppComponent : AppComponentMerged // Generate package com.amazon @Singleton interface AppComponentMerged : ${contributedSuperTypes}
167. @MergeComponent val className = ClassName( packageName = clazz.packageName.asString(), simpleNames = listOf("${clazz.innerClassNames()}Merged"), ) val scope = clazz.scope() val componentInterfaces = resolver.getDeclarationsFromPackage(LOOKUP_PACKAGE) .filterIsInstance<KSClassDeclaration>() .filter { it.scope().isSameAs(scope) } .toList()
168. @MergeComponent val className = ClassName( packageName = clazz.packageName.asString(), simpleNames = listOf("${clazz.innerClassNames()}Merged"), ) val scope = clazz.scope() val componentInterfaces = resolver.getDeclarationsFromPackage(LOOKUP_PACKAGE) .filterIsInstance<KSClassDeclaration>() .filter { it.scope().isSameAs(scope) } .toList()
169. @MergeComponent val className = ClassName( packageName = clazz.packageName.asString(), simpleNames = listOf("${clazz.innerClassNames()}Merged"), ) val scope = clazz.scope() val componentInterfaces = resolver.getDeclarationsFromPackage(LOOKUP_PACKAGE) .filterIsInstance<KSClassDeclaration>() .filter { it.scope().isSameAs(scope) } .toList()
170. @MergeComponent val fileSpec = FileSpec.builder(className) .addType( TypeSpec .interfaceBuilder(className) .addAnnotation(scope.toAnnotationSpec()) .addSuperinterfaces(componentInterfaces.map { it.toClassName() }) .build(), ) .build() fileSpec.writeTo( codeGenerator = codeGenerator, aggregating = true, originatingKSFiles = buildSet { add(clazz.requireContainingFile()) addAll(componentInterfaces.mapNotNull { it.containingFile }) }, )
171. @MergeComponent val fileSpec = FileSpec.builder(className) .addType( TypeSpec .interfaceBuilder(className) .addAnnotation(scope.toAnnotationSpec()) .addSuperinterfaces(componentInterfaces.map { it.toClassName() }) .build(), ) .build() fileSpec.writeTo( codeGenerator = codeGenerator, aggregating = true, originatingKSFiles = buildSet { add(clazz.requireContainingFile()) addAll(componentInterfaces.mapNotNull { it.containingFile }) }, )
172. @MergeComponent val fileSpec = FileSpec.builder(className) .addType( TypeSpec .interfaceBuilder(className) .addAnnotation(scope.toAnnotationSpec()) .addSuperinterfaces(componentInterfaces.map { it.toClassName() }) .build(), ) .build() fileSpec.writeTo( codeGenerator = codeGenerator, aggregating = true, originatingKSFiles = buildSet { add(clazz.requireContainingFile()) addAll(componentInterfaces.mapNotNull { it.containingFile }) }, )
173. kotlin-inject - Anvil @ContributesBinding @ContributesSubcomponent
174. kotlin-inject @Inject @Singleton class WeatherRepositoryImpl( client: HttpClient, ) : WeatherRepository interface WeatherRepositoryComponent { @Provides fun provideWeatherRepository( weatherRepository: WeatherRepositoryImpl ): WeatherRepository = weatherRepository }
175. kotlin-inject - Anvil @ContributesBinding @Inject @Singleton class WeatherRepositoryImpl( client: HttpClient, ) : WeatherRepository interface WeatherRepositoryComponent { @Provides fun provideWeatherRepository( weatherRepository: WeatherRepositoryImpl ): WeatherRepository = weatherRepository }
176. kotlin-inject - Anvil @ContributesBinding @Inject @Singleton class WeatherRepositoryImpl( client: HttpClient, ) : WeatherRepository
177. kotlin-inject interface WeatherComponent { val weatherRepository: WeatherRepository } @Singleton @Component interface AppComponent : WeatherRepositoryComponent, WeatherComponent
178. kotlin-inject - Anvil interface WeatherComponent { val weatherRepository: WeatherRepository } @Singleton @Component interface AppComponent : WeatherComponent
179. kotlin-inject - Anvil @ContributesTo @Singleton interface WeatherComponent { val weatherRepository: WeatherRepository } @Singleton @Component interface AppComponent
180. kotlin-inject - Anvil @ContributesTo @Singleton interface WeatherComponent { val weatherRepository: WeatherRepository } @Singleton @Component @MergeComponent interface AppComponent : AppComponentMerged
181. kotlin-inject https://github.com/evant/kotlin-inject/discussions/221
182. Summary • KSP is great ◦ KMP support, multiple rounds, deferred processing, incremental processing, … ◦ Simple introduction to the meta-programming world • kotlin-inject is great and improving • Find creative ways to make tools and libraries work for you
183. Extending kotlin-inject for fun & profit Ralf Wondratschek