Scaling Dagger: DI in a modular world

As your Android app grows in size, using a DI framework like Dagger becomes a necessity. But as your app keeps growing and aging, does Dagger scale well with it? Does it play well with modularized apps? How do you visualize and navigate the graph as complexity grows?

In this session we will describe the mechanisms that we use at Twitter to facilitate dependency injection, review the pain points we encountered with Dagger, and share some practical advice on how to address them. Finally, we’ll offer a sneak peek of the tools that built on Dagger to facilitate DI that we will open source in 2020.

Transcript

1. Scaling Dagger DI in a modular world Droidcon Madrid 2019
2. @CesarDielo César Puerta Technical Lead Twitter for Android @mrmans0n Nacho López Software Engineer Android Foundation Architecture
5. Author: Ben Sandofsky Date: Mon Jun 21 23:24:55 2010 -0700 Initial import.
6. Author: Ben Sandofsky Date: Mon Jun 21 23:24:55 2010 -0700 Initial import.
15. Periscope @PeriscopeCo You might have heard some news: It involves a blue bird. #YouCanGuessTheRest #WeJoinedTheFlockInJanuary 13 Mar 2015 629 761
16. +
21. D D
22. DI is important
23. DI is important Reusability for…
24. DI is important Testability for…
25. DI is important Correctness for…
26. DI is important Refactoring for…
27. regardless of app size DI is important
30. Static checks
31. Static checks Errors at compile time > Runtime errors
32. Description: [Dagger/MissingBinding] com.twitter.ui.util.UiArchLayoutContentViewProvider cannot be provided without an @Inject constructor or an @Provides-annotated method. Description: [Dagger/DuplicateBindings] com.twitter.ui.util.UiArchLayoutContentViewProvider is bound multiple times.
33. Code generation
34. Code generation Automating the creation of glue code
35. val inflater = LayoutInflater.from(context) val renderer = Renderer(inflater) val database = Database() val timeline = Timeline(database, renderer) class Renderer (database: Database, renderer: Renderer) class Timeline class Database() (inflater: LayoutInflater)
36. class Renderer (database: Database, renderer: Renderer) class Timeline class Database () (inflater: LayoutInflater) @Inject constructor @Inject constructor @Inject constructor
37. Graph Architecture
38. Graph Architecture Scoped object graphs mapping to the app lifecycle
39. Graph Architecture Scoped object graphs mapping to the app lifecycle @Component @Subcomponent
44. @ApplicationScope @UserScope @RetainedScope @ViewScope
45. @Component(modules = [ApplicationModule::class]) @ApplicationScope interface ApplicationObjectGraph
46. @Component(modules = [ApplicationModule::class]) @ApplicationScope interface ApplicationObjectGraph { fun userObjectGraphBuilder(): UserObjectGraph.Builder }
47. @Subcomponent(modules = [UserModule::class]) @UserScope interface UserObjectGraph @Component(modules = [ApplicationModule::class]) @ApplicationScope interface ApplicationObjectGraph { fun userObjectGraphBuilder(): UserObjectGraph.Builder }
48. { fun featureRetainedBuilder(): FeatureRetainedObjectGraph.Builder } @Subcomponent(modules = [UserModule::class]) @UserScope interface UserObjectGraph @Component(modules = [ApplicationModule::class]) @ApplicationScope interface ApplicationObjectGraph { fun userObjectGraphBuilder(): UserObjectGraph.Builder }
49. { fun featureRetainedBuilder(): FeatureRetainedObjectGraph.Builder } @Subcomponent(modules = [UserModule::class]) @UserScope interface UserObjectGraph @ApplicationScope interface ApplicationObjectGraph { fun userObjectGraphBuilder(): UserObjectGraph.Builder } @Subcomponent(modules = [FeatureRetainedModule::class]) @RetainedScope interface FeatureRetainedObjectGraph
50. { fun featureRetainedBuilder(): FeatureRetainedObjectGraph.Builder } @Subcomponent(modules = [UserModule::class]) @UserScope interface UserObjectGraph @ApplicationScope interface ApplicationObjectGraph { fun userObjectGraphBuilder(): UserObjectGraph.Builder } @Subcomponent(modules = [FeatureRetainedModule::class]) @RetainedScope interface FeatureRetainedObjectGraph { fun featureViewGraphBuilder(): FeatureViewObjectGraph.Builder }
51. { fun featureRetainedBuilder(): FeatureRetainedObjectGraph.Builder } @UserScope interface UserObjectGraph @Subcomponent(modules = [FeatureRetainedModule::class]) @RetainedScope interface FeatureRetainedObjectGraph { fun featureViewGraphBuilder(): FeatureViewObjectGraph.Builder } @Subcomponent(modules = [FeatureViewModule::class]) @ViewScope interface FeatureViewObjectGraph
52. { fun featureRetainedBuilder(): FeatureRetainedObjectGraph.Builder } @UserScope interface UserObjectGraph Components or ? Subcomponents @ApplicationScope @UserScope @RetainedScope @ViewScope
53. Components for the root graph for the nested graphs Subcomponents @ApplicationScope @UserScope @RetainedScope @ViewScope
54. Where do we place our graphs?
56. @ApplicationScope @UserScope @RetainedScope @ViewScope
57. Let’s compose a Tweet
58. :features:composer @RetainedScope @ViewScope @ApplicationScope @UserScope
59. :features:composer ComposerActivity ComposerViewModel ComposerViewDelegate @RetainedScope @ViewScope @ApplicationScope @UserScope
60. :features:composer ComposerActivity ComposerViewModel ComposerViewDelegate @RetainedScope @ViewScope @ApplicationScope @UserScope
61. :subsystems:tweets TweetRepository :features:composer @RetainedScope @ViewScope @ApplicationScope @UserScope
62. :subsystems:tweets TweetRepository :features:composer @RetainedScope @ViewScope @ApplicationScope @UserScope
63. :subsystems:tweets TweetRepository :features:composer @RetainedScope @ViewScope @ApplicationScope @UserScope
64. :subsystems:tweets TweetRepository :features:composer @RetainedScope @ViewScope @ApplicationScope @UserScope
65. :twitter:media ImageUploader :features:composer :subsystems:tweets @RetainedScope @ViewScope @UserScope @ApplicationScope
66. :twitter:media ImageUploader :features:composer :subsystems:tweets @RetainedScope @ViewScope @ApplicationScope @UserScope
67. :twitter:media ImageUploader :features:composer :subsystems:tweets @RetainedScope @ViewScope @ApplicationScope @UserScope
68. :twitter:media ImageUploader :features:composer :subsystems:tweets @RetainedScope @ViewScope @ApplicationScope @UserScope
69. :core:network OkHttpClient :features:composer :subsystems:tweets :twitter:media @RetainedScope @ViewScope @UserScope @ApplicationScope
70. :core:network OkHttpClient :features:composer :subsystems:tweets :twitter:media @RetainedScope @ViewScope @ApplicationScope @UserScope
71. :core:network :features:composer :subsystems:tweets :twitter:media @RetainedScope @ViewScope @ApplicationScope @UserScope ComposerNotifHandler
72. :core:network :features:composer :subsystems:tweets :twitter:media @RetainedScope @ViewScope @ApplicationScope @UserScope ComposerNotifHandler
73. :core:network :features:composer :subsystems:tweets :twitter:media @RetainedScope @ViewScope @ApplicationScope @UserScope M M M M M M
74. :core:network :features:composer :subsystems:tweets :twitter:media @RetainedScope @ViewScope @ApplicationScope @UserScope M M M M M M
75. Ideal Location
76. App wide graphs definitions belong in the top gradle module. Ideal Location
77. Graphs can be large!
78. @Component @ApplicationScope interface ApplicationObjectGraph } fun composerLauncher(): ComposerLauncher fun composerNotificationHandler(): ComposerNotifHandler { ]) (modules = [ComposerAppModule::class
79. @Component @ApplicationScope interface ApplicationObjectGraph } fun composerLauncher(): ComposerLauncher fun composerNotificationHandler(): ComposerNotifHandler fun tweetsRepository(): TweetsRepository fun tweetsDataSource(): TweetsDataSource fun imageLoader(): ImageLoader { , TweetRepositoryAppModule::cl (modules = [ComposerAppModule::class
80. fun okHttpClient(): OkHttpClient fun twitterApiService(): TwitterApiService @Component @ApplicationScope interface ApplicationObjectGraph fun composerLauncher(): ComposerLauncher fun composerNotificationHandler(): ComposerNotifHandler fun tweetsRepository(): TweetsRepository fun tweetsDataSource(): TweetsDataSource fun imageLoader(): ImageLoader { fun loginController(): LoginController fun loginAssistController(): LoginAssistController fun appEventTracker(): AppEventTracker fun installationReferrer(): InstallationReferrer fun jobManager(): JobManager fun playServicesUtil(): PlayServicesUtil fun httpRequestController(): HttpRequestController fun registrableHeadsetPlugReceiver(): RegistrableHeadsetPlugReceiver , TweetRepositoryAppModule::cl (modules = [ComposerAppModule::class
81. fun okHttpClient(): OkHttpClient fun twitterApiService(): TwitterApiService @Component @ApplicationScope interface ApplicationObjectGraph fun composerLauncher(): ComposerLauncher fun composerNotificationHandler(): ComposerNotifHandler fun tweetsRepository(): TweetsRepository fun tweetsDataSource(): TweetsDataSource fun imageLoader(): ImageLoader { fun loginController(): LoginController fun loginAssistController(): LoginAssistController fun appEventTracker(): AppEventTracker fun installationReferrer(): InstallationReferrer fun jobManager(): JobManager fun playServicesUtil(): PlayServicesUtil fun httpRequestController(): HttpRequestController fun registrableHeadsetPlugReceiver(): RegistrableHeadsetPlugReceiver , TweetRepositoryAppModule::cl (modules = [ComposerAppModule::class
82. fun okHttpClient(): OkHttpClient fun twitterApiService(): TwitterApiService @Component @ApplicationScope interface ApplicationObjectGraph fun composerLauncher(): ComposerLauncher fun composerNotificationHandler(): ComposerNotifHandler fun tweetsRepository(): TweetsRepository fun tweetsDataSource(): TweetsDataSource fun imageLoader(): ImageLoader { fun loginController(): LoginController fun loginAssistController(): LoginAssistController fun appEventTracker(): AppEventTracker fun installationReferrer(): InstallationReferrer fun jobManager(): JobManager fun playServicesUtil(): PlayServicesUtil fun httpRequestController(): HttpRequestController fun registrableHeadsetPlugReceiver(): RegistrableHeadsetPlugReceiver , TweetRepositoryAppModule::cl (modules = [ComposerAppModule::class
83. Subgraphs
84. Subgraphs Slices of an Object Graph
85. @Component @ApplicationScope interface ApplicationObjectGraph { } fun okHttpClient(): OkHttpClient fun twitterApiService(): TwitterApiService fun composerLauncher(): ComposerLauncher fun composerNotificationHandler(): ComposerNotifHandler fun tweetsRepository(): TweetsRepository fun tweetsDataSource(): TweetsDataSource fun imageLoader(): ImageLoader :app:twitter
86. : @Component @ApplicationScope interface ApplicationObjectGraph { } fun okHttpClient(): OkHttpClient fun twitterApiService(): TwitterApiService fun composerLauncher(): ComposerLauncher fun composerNotificationHandler(): ComposerNotifHandler fun tweetsRepository(): TweetsRepository fun tweetsDataSource(): TweetsDataSource fun imageLoader(): ImageLoader ComposerAppSubgraph interface ComposerAppSubgraph { } :app:twitter :features:composer
87. : @Component @ApplicationScope interface ApplicationObjectGraph { } fun okHttpClient(): OkHttpClient fun twitterApiService(): TwitterApiService fun tweetsRepository(): TweetsRepository fun tweetsDataSource(): TweetsDataSource fun imageLoader(): ImageLoader ComposerAppSubgraph :app:twitter
88. @Component @ApplicationScope interface ApplicationObjectGraph , : { } fun okHttpClient(): OkHttpClient fun twitterApiService(): TwitterApiService fun tweetsRepository(): TweetsRepository fun tweetsDataSource(): TweetsDataSource fun imageLoader(): ImageLoader ComposerAppSubgraph interface TweetRepositoryAppSubgraph { } TweetRepositoryAppSubgraph :app:twitter :subsystems:tweets
89. @Component @ApplicationScope interface ApplicationObjectGraph , : { } fun okHttpClient(): OkHttpClient fun twitterApiService(): TwitterApiService fun imageLoader(): ImageLoader ComposerAppSubgraph TweetRepositoryAppSubgraph :app:twitter
90. @Component @ApplicationScope interface ApplicationObjectGraph , : { } fun okHttpClient(): OkHttpClient fun twitterApiService(): TwitterApiService fun imageLoader(): ImageLoader ComposerAppSubgraph TweetRepositoryAppSubgraph interface MediaAppSubgraph { } MediaAppSubgraph , :app:twitter :twitter:media
91. @Component @ApplicationScope interface ApplicationObjectGraph , : { } fun okHttpClient(): OkHttpClient fun twitterApiService(): TwitterApiService ComposerAppSubgraph TweetRepositoryAppSubgraph MediaAppSubgraph , :app:twitter
92. @Component @ApplicationScope interface ApplicationObjectGraph , : fun okHttpClient(): OkHttpClient fun twitterApiService(): TwitterApiService ComposerAppSubgraph TweetRepositoryAppSubgraph MediaAppSubgraph , interface CoreNetworkAppSubgraph { } CoreNetworkAppSubgraph , :core:network :app:twitter
93. @Component @ApplicationScope interface ApplicationObjectGraph , : ComposerAppSubgraph TweetRepositoryAppSubgraph MediaAppSubgraph , CoreNetworkAppSubgraph , :app:twitter ApplicationObjectGraph
94. :core:network :features:composer :subsystems:tweets :twitter:media TweetRepositoryAppSubgraph MediaAppSubgraph CoreNetworkAppSubgraph ApplicationObjectGraph ComposerAppSubgraph
95. :core:network :features:composer :subsystems:tweets :twitter:media TweetRepositoryAppSubgraph MediaAppSubgraph CoreNetworkAppSubgraph ApplicationObjectGraph ComposerAppSubgraph
96. ApplicationObjectGraph UserObjectGraph Multiple Retained and ViewObjectGraphs
97. ApplicationObjectGraph UserObjectGraph Multiple Retained and ViewObjectGraphs
98. Big monolithic graphs
99. Big monolithic graphs Scatter the definitions of the object graphs into subgraphs that can live in the gradle modules where the bindings are actually defined.
100. How to instantiate your graphs?
101. component = .application(this) .build() class MyApplication : Application { private lateinit var component: ApplicationObjectGraph override fun onCreate() { } super.onCreate() } DaggerApplicationObjectGraph.builder()
102. component = .application(this) .build() class MyApplication : Application { private lateinit var component: ApplicationObjectGraph override fun onCreate() { } super.onCreate() } DaggerApplicationObjectGraph.builder()
103. Dagger.getObjectGraphBuilder<ApplicationObjectGraph>() component = .application(this) .build() class MyApplication : Application { private lateinit var component: ApplicationObjectGraph override fun onCreate() { } super.onCreate() }
104. fun <B : Any> getObjectGraphBuilder(builderClass: Class<B>): B } } class Dagger { companion object { inline fun <reified B : Any> getObjectGraphBuilder(): B = getObjectGraphBuilder(B::class.java) } {
105. fun <B : Any> getObjectGraphBuilder(builderClass: Class<B>): B } } class Dagger { companion object { inline fun <reified B : Any> getObjectGraphBuilder(): B = getObjectGraphBuilder(B::class.java) } {
106. if (!builderClass.isAnnotationPresent(Component.Builder::class.java)) { throw IllegalArgumentException("Not a component builder class: $builderClass") } val componentClass = builderClass.enclosingClass ?: throw IllegalStateException("Component builder is not enclosed in a component.") val generatedDaggerClassName = getDaggerComponentImplementationClassName(componentClass) val generatedObjectGraphClass = ReflectionUtils.loadClass<Any>(generatedDaggerClassName) ?: throw IllegalStateException("Generated Dagger class can't be found: $generatedDagge val builderMethod = ReflectionUtils.getMethod(generatedObjectGraphClass, "builder") ?: throw IllegalStateException("The Dagger component generated class does not contain return ReflectionUtils.invokeMethod<B>(builderMethod, null) ?: throw IllegalStateException("The builder() method returned null.") fun <B : Any> getObjectGraphBuilder(builderClass: Class<B>): B } } class Dagger { companion object { inline fun <reified B : Any> getObjectGraphBuilder(): B = getObjectGraphBuilder(B::class.java) } {
107. if (!builderClass.isAnnotationPresent(Component.Builder::class.java)) { throw IllegalArgumentException("Not a component builder class: $builderClass") } val componentClass = builderClass.enclosingClass ?: throw IllegalStateException("Component builder is not enclosed in a component.") val generatedDaggerClassName = getDaggerComponentImplementationClassName(componentClass) val generatedObjectGraphClass = ReflectionUtils.loadClass<Any>(generatedDaggerClassName) ?: throw IllegalStateException("Generated Dagger class can't be found: $generatedDagge val builderMethod = ReflectionUtils.getMethod(generatedObjectGraphClass, "builder") ?: throw IllegalStateException("The Dagger component generated class does not contain return ReflectionUtils.invokeMethod<B>(builderMethod, null) ?: throw IllegalStateException("The builder() method returned null.") fun <B : Any> getObjectGraphBuilder(builderClass: Class<B>): B } } class Dagger { companion object { inline fun <reified B : Any> getObjectGraphBuilder(): B = getObjectGraphBuilder(B::class.java) } TL;DR Use reflection once to find and instantiate the graph’s Component.Builder {
108. if (!builderClass.isAnnotationPresent(Component.Builder::class.java)) { throw IllegalArgumentException("Not a component builder class: $builderClass") } val componentClass = builderClass.enclosingClass ?: throw IllegalStateException("Component builder is not enclosed in a component.") val generatedDaggerClassName = getDaggerComponentImplementationClassName(componentClass) val generatedObjectGraphClass = ReflectionUtils.loadClass<Any>(generatedDaggerClassName) ?: throw IllegalStateException("Generated Dagger class can't be found: $generatedDagge val builderMethod = ReflectionUtils.getMethod(generatedObjectGraphClass, "builder") ?: throw IllegalStateException("The Dagger component generated class does not contain return ReflectionUtils.invokeMethod<B>(builderMethod, null) ?: throw IllegalStateException("The builder() method returned null.") fun <B : Any> getObjectGraphBuilder(builderClass: Class<B>): B } } class Dagger { companion object { inline fun <reified B : Any> getObjectGraphBuilder(): B = getObjectGraphBuilder(B::class.java) } Don’t worry! We will share the code in GitHub! {
109. Referencing generated code DaggerApplicationObjectGraph.builder()
110. Referencing generated code Use reflection once to grab the root object graph builder. Dagger.getObjectGraphBuilder<ApplicationObjectGraph>() DaggerApplicationObjectGraph.builder()
111. How to access graphs at the top from intermediate layers?
112. ApplicationObjectGraph
113. ApplicationObjectGraph :twitter:media ImageUploader L LegacyActivity
114. :twitter:media L ImageUploader LegacyActivity ApplicationObjectGraph
115. :twitter:media MediaAppSubgraph L LegacyActivity ApplicationObjectGraph
116. object ApplicationObjectGraphProvider { var graphProvider: Any? }
117. component = Dagger.getObjectGraphBuilder<ApplicationObjectGraph>() .application(this) .build() class MyApplication : Application { private lateinit var component: ApplicationObjectGraph override fun onCreate() { } super.onCreate() }
118. component = Dagger.getObjectGraphBuilder<ApplicationObjectGraph>() .application(this) .build() class MyApplication : Application { private lateinit var component: ApplicationObjectGraph override fun onCreate() { } super.onCreate() }
119. super.onCreate() } ApplicationObjectGraphProvider.graphProvider = Dagger.getObjectGraphBuilder<ApplicationObjectGraph>() .application(this) .build() class MyApplication : Application { override fun onCreate() { }
120. ApplicationObjectGraph ApplicationObjectGraphProvider
121. ApplicationObjectGraph ApplicationObjectGraphProvider :twitter:media L ImageUploader LegacyActivity MediaAppSubgraph
122. (ApplicationObjectGraphProvider.graphProvider as MediaAppSubgraph).imageUploader()
123. object ApplicationObjectGraphProvider { } fun <T> getSubgraph(clazz: Class<T>): T var graphProvider: Any?
124. object ApplicationObjectGraphProvider { } fun <T> getSubgraph(clazz: Class<T>): T var graphProvider: Any? { return clazz.cast(graphProvider) }
125. fun imageUploader(): ImageUploader interface MediaAppSubgraph { }
126. fun imageUploader(): ImageUploader interface MediaAppSubgraph { } companion object { fun get(): MediaAppSubgraph { return ApplicationObjectGraphProvider.graphProvider .getSubgraph(MediaAppSubgraph::class.java) }
127. val uploader = MediaAppSubgraph.get().imageUploader() fun imageUploader(): ImageUploader interface MediaAppSubgraph { } companion object { fun get(): MediaAppSubgraph { return ApplicationObjectGraphProvider.graphProvider .getSubgraph(MediaAppSubgraph::class.java) }
128. val uploader = MediaAppSubgraph.get().imageUploader()
129. Grabbing objects from Dagger w/o visibility MediaAppSubgraph L LegacyActivity ApplicationObjectGraph
130. Grabbing objects from Dagger w/o visibility Wrap your Application and User graphs in providers that can be statically obtained, and add a way to extract subgraphs from them. ApplicationObjectGraphProvider UserObjectGraphProvider MediaAppSubgraph L LegacyActivity
131. How would that work in testing?
132. object ApplicationObjectGraphProvider { } var graphProvider: Any? private val mapping: Map<Class<*>, Any> = mutableMapOf() fun <T> overrideSubgraph(clazz: Class<T>, subgraph: T) { mapping[clazz] = subgraph } fun <T> getSubgraph(clazz: Class<T>): T { if (mapping.containsKey(clazz)) return clazz.cast(mapping[clazz]) return clazz.cast(graphProvider) }
133. object ApplicationObjectGraphProvider { } var graphProvider: Any? private val mapping: Map<Class<*>, Any> = mutableMapOf() fun <T> overrideSubgraph(clazz: Class<T>, subgraph: T) { mapping[clazz] = subgraph } fun <T> getSubgraph(clazz: Class<T>): T { if (mapping.containsKey(clazz)) return clazz.cast(mapping[clazz]) return clazz.cast(graphProvider) }
134. How to decouple features?
135. How to decouple features? The app navigation case
137. ComposerActivity MainActivity DMActivity TweetDetailActivity C D M TD
138. ComposerActivity MainActivity DMActivity TweetDetailActivity C D M TD
139. ComposerActivity MainActivity DMActivity TweetDetailActivity C D M TD
140. ComposerActivity MainActivity DMActivity TweetDetailActivity C D M TD Circular Dependency!
141. ComposerActivity MainActivity TweetDetailActivity C D M TD DMActivity :subsystems:navigation
142. ComposerActivity MainActivity TweetDetailActivity C D M TD Intent().putExtra(…) DMActivity :subsystems:navigation C D M TD C D M TD Intent factories
143. ComposerActivity MainActivity TweetDetailActivity C D M TD DMActivity :subsystems:navigation C D M TD Intent factories ActivityArgs
144. ComposerActivity MainActivity TweetDetailActivity C D M TD DMActivity :subsystems:navigation TD M D C ActivityArgs
145. ComposerActivity MainActivity TweetDetailActivity C D M TD DMActivity :subsystems:navigation TD M D C ActivityArgs
146. interface ActivityArgs { fun toIntent(context: Context, clazz: Class<out Activity>): Intent }
147. override fun toIntent(context: Context, clazz: Class<out Activity>): { .apply { putExtra("user_id", uid) putExtra("text", text) } } interface ActivityArgs { fun toIntent(context: Context, clazz: Class<out Activity>): Intent } data class ComposerArgs(val uid: Long, val text: String): ActivityArgs { } return Intent(context, clazz)
148. override fun toIntent(context: Context, clazz: Class<out Activity>): { .apply { putExtra("user_id", uid) putExtra("text", text) } } interface ActivityArgs { fun toIntent(context: Context, clazz: Class<out Activity>): Intent } data class ComposerArgs(val uid: Long, val text: String): ActivityArgs { } return Intent(context, clazz)
149. Service Discovery
150. Service Discovery Multibindings
151. C D TD ComposerArgs TweetDetailArgs DMArgs :features:tweetdetail :features:dm :features:composer @Multibinds
152. C D TD ComposerArgs TweetDetailArgs DMArgs :features:tweetdetail :features:dm :features:composer @Multibinds
153. C D TD ComposerArgs TweetDetailArgs DMArgs :features:tweetdetail :features:dm :features:composer @Multibinds
154. C D TD ComposerArgs TweetDetailArgs DMArgs :features:tweetdetail :features:dm :features:composer Map<Class<out ActivityArgs>, Class<out Activity>> C D TD ComposerActivity DMActivity TweetDetailActivity
155. @Module object ComposerModule { @Provides @ApplicationScope fun provideActivityClass: Class<out Activity> { } } :features:composer @ActivityArgsKey(ComposerArgs::class) @IntoMap return ComposerActivity::class.java
156. @Module object ComposerModule { @Provides @ApplicationScope fun provideActivityClass: Class<out Activity> { } } :features:composer @ActivityArgsKey(ComposerArgs::class) @IntoMap return ComposerActivity::class.java
157. @Module object ComposerModule { @Provides @ApplicationScope fun provideActivityClass: Class<out Activity> { } } :features:composer @ActivityArgsKey(ComposerArgs::class) @IntoMap return ComposerActivity::class.java
158. @Module object ComposerModule { @Provides @ApplicationScope fun provideActivityClass: Class<out Activity> { } } :features:composer @ActivityArgsKey(ComposerArgs::class) @IntoMap return ComposerActivity::class.java
159. @ApplicationScope class ActivityStarter @Inject constructor( ) private val activityMap: Map<Class<out ActivityArgs>, Class<out Activity>> { fun startActivity(context: Context, args: ActivityArgs) { } } val intent = args.toIntent(context, activityMap[args.javaClass]) context.startActivity(intent)
160. @ApplicationScope class ActivityStarter @Inject constructor( ) { fun startActivity(context: Context, args: ActivityArgs) { } } val intent = args.toIntent(context, activityMap[args.javaClass]) context.startActivity(intent) private val activityMap: Map<Class<out ActivityArgs>, Class<out Activity>>
161. { fun startActivity(context: Context, args: ActivityArgs) { } } @ApplicationScope class ActivityStarter @Inject constructor( ) val intent = args.toIntent(context, activityMap[args.javaClass]) context.startActivity(intent) private val activityMap: Map<Class<out ActivityArgs>, Class<out Activity>>
162. { fun startActivity(context: Context, args: ActivityArgs) { } } @ApplicationScope class ActivityStarter @Inject constructor( ) val intent = args.toIntent(context, activityMap[args.javaClass]) context.startActivity(intent) private val activityMap: Map<Class<out ActivityArgs>, Class<out Activity>>
163. C TD Start an Activity we can’t see at compile time
164. C D TD C D TD Start an Activity we can’t see at compile time At compile time you might not see everything, but at runtime it is all there. Let’s use Multibindings to aggregate references at compile time and resolve them at runtime.
166. Initializers
167. Notification Handlers
168. Deeplink Handlers
171. Subgraphs
172. Subgraphs are not atomic units
173. S ApplicationObjectGraph S S S S S S S
174. S ApplicationObjectGraph M S M S M S M S M S M S M S M
175. S ApplicationObjectGraph M S M S M S M S S M S M S M @Component(modules = [ ComposerAppModule::class, TweetDetailAppModule::class, HomeAppModule::class, ExploreAppModule::class, CoreAppModule::class, CoreNetworkAppModule::class, MediaAppModule::class, VideoAppModule::class, NavigationAppModule::class, LoggingAppModule::class, TimelineAppModule::class, … and on and on and on ]) @ApplicationScope interface ApplicationObjectGraph: M
176. ApplicationObjectGraph M M M M M M M M TimelineAppModule::class, … and on and on and on ]) @ApplicationScope interface ApplicationObjectGraph: InitializationSubgraph, ComposerAppSubgraph, TweetDetailAppSubgraph, HomeAppSubgraph, ExploreAppSubgraph, CoreAppSubgraph, CoreNetworkAppSubgraph, MediaAppSubgraph, VideoAppSubgraph, NavigationAppSubgraph, … and on and on and on S S S S S S S S
177. S M
178. @Component(modules = [ … and on and on and on ]) @ApplicationScope interface ApplicationObjectGraph: InitializationSubgraph, TweetDetailAppSubgraph, @Component(modules = [ … and on and on and on ]) @ApplicationScope interface ApplicationObjectGraph: InitializationSubgraph, MapSubgraph, S M
179. @Component(modules = [ BroadcastAppModule::class, … and on and on and on ]) @ApplicationScope interface ApplicationObjectGraph: InitializationSubgraph, BroadcastAppSubgraph, TweetDetailAppSubgraph, @Component(modules = [ BroadcastAppModule::class, … and on and on and on ]) @ApplicationScope interface ApplicationObjectGraph: InitializationSubgraph, BroadcastAppSubgraph, MapSubgraph, S M
181. { fun broadcastController(): BroadcastController } @Module { @Binds @ApplicationScope fun bindBcastController(impl: BroadcastControllerImpl): BroadcastController } object BroadcastAppModule interface BroadcastAppSubgraph
182. interface BroadcastAppSubgraph { fun broadcastController(): BroadcastController } @Subgraph @Module { @Binds @ApplicationScope fun bindBcastController(impl: BroadcastControllerImpl): BroadcastController } object BroadcastAppModule interface BroadcastAppSubgraph
183. @ApplicationScope interface BroadcastAppSubgraph { fun broadcastController(): BroadcastController } @Subgraph @Module { @Binds @ApplicationScope fun bindBcastController(impl: BroadcastControllerImpl): BroadcastController } object BroadcastAppModule interface BroadcastAppSubgraph
184. @ApplicationScope interface BroadcastAppSubgraph { fun broadcastController(): BroadcastController } @Subgraph @Subgraph(modules = [BroadcastAppModule::class]) @Module { @Binds @ApplicationScope fun bindBcastController(impl: BroadcastControllerImpl): BroadcastController } object BroadcastAppModule interface BroadcastAppSubgraph
185. @ApplicationScope interface ApplicationObjectGraph : BroadcastAppSubgraph, InitializationSubgraph, ... (modules = [BroadcastAppModule::class, ...]) @Component
186. @ApplicationScope interface ApplicationObjectGraph : BroadcastAppSubgraph, InitializationSubgraph, ... (modules = [BroadcastAppModule::class, ...]) @Component
187. @ApplicationScope interface ApplicationObjectGraph : BroadcastAppSubgraph, InitializationSubgraph, ... @ObjectGraph
188. @UserScope interface UserObjectGraph : UserManagerSubgraph, TweetRepository, ... (modules = [UserManagerModule::class, ...]) @ApplicationScope interface ApplicationObjectGraph : BroadcastAppSubgraph, InitializationSubgraph, ... @ObjectGraph @Subcomponent
189. @UserScope interface UserObjectGraph : UserManagerSubgraph, TweetRepository, ... (modules = [UserManagerModule::class, ...]) @ApplicationScope interface ApplicationObjectGraph : BroadcastAppSubgraph, InitializationSubgraph, ... @ObjectGraph @Subcomponent
190. @UserScope interface UserObjectGraph : UserManagerSubgraph, TweetRepository, ... @ApplicationScope interface ApplicationObjectGraph : BroadcastAppSubgraph, InitializationSubgraph, ... @ObjectGraph @ObjectGraph
191. @ObjectGraph @Subgraph
192. Annotation Processor @ObjectGraph @Subgraph @Component @Subcomponent
193. @ObjectGraph @Subgraph Annotation Processor @Component @Subcomponent
194. Annotation Processor @ObjectGraph @Subgraph @Component @Subcomponent
195. Fully Dagger Compatible Annotation Processor
196. Subgraphs
197. Subgraphs are not encapsulated
198. S S S S S S
199. S S S S S S
200. S S S S S S
201. S
202. S @ApplicationScope interface BroadcastAppSubgraph { fun broadcastController(): BroadcastController } @Subgraph(modules = [BroadcastAppModule::class])
203. @Subgraph( subgraphDependencies = [ CoreNetworkSubgraph::class, VideoPlayerSubgraph::class ]) S @ApplicationScope interface BroadcastAppSubgraph { fun broadcastController(): BroadcastController } @Subgraph @Subgraph(modules = [BroadcastAppModule::class],
204. S ApplicationObjectGraph S S S S S S S
205. S ApplicationObjectGraph S S S S S S S
206. S ApplicationObjectGraph S S S S S S S
207. Subgraphs
208. Subgraphs are not self documenting
209. Subgraphs are not self documenting
210. @Subgraph( subgraphDependencies = [ CoreNetworkSubgraph::class, VideoPlayerSubgraph::class ]) @ApplicationScope interface BroadcastAppSubgraph { fun broadcastController(): BroadcastController } @Subgraph @Subgraph(modules = [BroadcastAppModule::class],
211. @Subgraph( subgraphDependencies = [ CoreNetworkSubgraph::class, VideoPlayerSubgraph::class ]) @ApplicationScope interface BroadcastAppSubgraph { fun broadcastController(): BroadcastController } @Subgraph @Subgraph(modules = [BroadcastAppModule::class],
212. @Subgraph( subgraphDependencies = [ CoreNetworkSubgraph::class, VideoPlayerSubgraph::class ]) @ApplicationScope interface BroadcastAppSubgraph { fun broadcastController(): BroadcastController } @Subgraph @Subgraph(modules = [BroadcastAppModule::class],
213. @Subgraph( subgraphDependencies = [ CoreNetworkSubgraph::class, VideoPlayerSubgraph::class ]) @ApplicationScope interface BroadcastAppSubgraph { fun broadcastController(): BroadcastController } @Subgraph @Subgraph(modules = [BroadcastAppModule::class],
214. Graphs
215. Graphs are hard to maintain
216. @ObjectGraph @ApplicationScope interface ApplicationObjectGraph: InitializationSubgraph, BroadcastAppSubgraph, TweetDetailAppSubgraph, HomeAppSubgraph, ExploreAppSubgraph, CoreAppSubgraph, CoreNetworkAppSubgraph, MediaAppSubgraph, VideoPlayerSubgraph, NavigationAppSubgraph, TweetUploadAppSubgraph, PerformanceMetricsAppSubgraph, DMAppSubgraph, JSONModelsAppSubgraph, DynamicModulesAppSubgraph, NotificationsAppSubgraph,
217. @ObjectGraph @ApplicationScope interface ApplicationObjectGraph: InitializationSubgraph, BroadcastAppSubgraph, TweetDetailAppSubgraph, HomeAppSubgraph, ExploreAppSubgraph, CoreAppSubgraph, CoreNetworkAppSubgraph, MediaAppSubgraph, VideoPlayerSubgraph, NavigationAppSubgraph, TweetUploadAppSubgraph, PerformanceMetricsAppSubgraph, DMAppSubgraph, JSONModelsAppSubgraph, DynamicModulesAppSubgraph, NotificationsAppSubgraph, This is actually insane
218. Annotation Processor @ObjectGraph @ApplicationScope interface ApplicationObjectGraph: InitializationSubgraph, BroadcastAppSubgraph, TweetDetailAppSubgraph, HomeAppSubgraph, ExploreAppSubgraph, CoreAppSubgraph, CoreNetworkAppSubgraph, MediaAppSubgraph, VideoPlayerSubgraph, NavigationAppSubgraph, TweetUploadAppSubgraph, PerformanceMetricsAppSubgraph, DMAppSubgraph, JSONModelsAppSubgraph, DynamicModulesAppSubgraph, NotificationsAppSubgraph,
219. Annotation Processor @ObjectGraph @ApplicationScope interface ApplicationObjectGraph: InitializationSubgraph, BroadcastAppSubgraph, TweetDetailAppSubgraph, HomeAppSubgraph, ExploreAppSubgraph, CoreAppSubgraph, CoreNetworkAppSubgraph, MediaAppSubgraph, VideoPlayerSubgraph, NavigationAppSubgraph, TweetUploadAppSubgraph, PerformanceMetricsAppSubgraph, DMAppSubgraph, JSONModelsAppSubgraph, DynamicModulesAppSubgraph, NotificationsAppSubgraph,
220. @ObjectGraph @ApplicationScope interface ApplicationObjectGraph Annotation Processor Automatic Discovery
221. S ApplicationObjectGraph S S S S S S S
222. S ApplicationObjectGraph S S S S S S S
223. Subgraphs
224. Subgraphs are not reusable
225. CoreNetworkSubgraph OkHttpClient Cache Set<Interceptor> CoreNetworkSubgraph :core:network
226. PeriscopeNetworkSubgraph :periscope:network CoreNetworkSubgraph OkHttpClient Cache Set<Interceptor> CoreNetworkSubgraph :core:network
227. CoreNetworkSubgraph OkHttpClient Cache Set<Interceptor> CoreNetworkSubgraph :core:network PeriscopeNetworkSubgraph :periscope:network
228. open class CoreNetworkSubgraph { fun okHttpClient(): OkHttpClient = … fun interceptors(): Set<Interceptor> = … } fun cache(): Cache = Cache()
229. class PeriscopeNetworkSubgraph : CoreNetworkSubgraph { override fun cache(): Cache = PeriscopeCachePolicy() } open fun cache(): Cache = Cache() open class CoreNetworkSubgraph { fun okHttpClient(): OkHttpClient = … fun interceptors(): Set<Interceptor> = … }
230. @Subgraph(module = [CoreNetworkModule::class]) @Open interface CoreNetworkSubgraph { fun okHttpClient(): OkHttpClient @Open fun cache(): Cache fun interceptors(): Set<Interceptor> }
231. @Subgraph(module = [CoreNetworkModule::class]) @Open interface CoreNetworkSubgraph { fun okHttpClient(): OkHttpClient @Open fun cache(): Cache fun interceptors(): Set<Interceptor> } @Subgraph interface PeriscopeNetworkSubgraph : CoreNetworkSubgraph { @Override @Binds fun bindCache(cache: PeriscopeCache): Cache }
232. Subgraphs
233. Subgraphs don’t support inversion of dependencies
234. interface DatabaseSubgraph { fun migrationManager(): MigrationManager } fun schema(): Schema @Subgraph
235. interface DatabaseSubgraph { fun migrationManager(): MigrationManager } fun schema(): Schema @Subgraph @Abstract @Abstract
236. interface DatabaseSubgraph { fun migrationManager(): MigrationManager } fun schema(): Schema @Subgraph @Abstract @Abstract @Subgraph interface TwitterDatabaseSubgraph : DatabaseSubgraph { @Binds fun schema(bound: TwitterSchema): Schema }
237. And more!
238. And more!
239. And more!
240. And more!
241. Annotation Processor
242. Scythe Scythe
243. Scythe OOP concepts for DI IDE support Better build times Binding overrides Modular scalability Self documentation Reusability Automatic discovery Completeness validation Factory bindings Assisted Injection Compatible with Dagger
244. Scythe Open-source launch for everybody in 2020
245. @CesarDielo César @mrmans0n Nacho
246. @CesarDielo César @mrmans0n Nacho Thank you! More questions? Follow ups from this talk? Hit us up on Twitter!