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Extending kotlin-inject
for fun & profit
June 6th, 2024
Ralf Wondratschek
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https://www.youtube.com/watch?v=xESX82kwjn4
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No content
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https://www.youtube.com/watch?v=0T_zvUEqsD4
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Background
https://ralf-wondratschek.com/presentations
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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
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Dagger 2
Provider side Component Injection side
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interface WeatherRepository {
fun provideForecast(location: Location): Forecast
}
Dagger 2
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Dagger 2
interface WeatherRepository {
fun provideForecast(location: Location): Forecast
}
class WeatherRepositoryImpl(
client: HttpClient,
) : WeatherRepository {
...
}
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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)
}
}
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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)
}
}
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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)
}
}
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Dagger 2
@Singleton
@Component(
modules = [
WeatherRepositoryModule::class,
]
)
interface AppComponent
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Dagger 2
@Singleton
@Component(
modules = [
WeatherRepositoryModule::class,
]
)
interface AppComponent
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@Component(
modules = [
WeatherRepositoryModule::class,
]
)
interface AppComponent
Dagger 2
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Dagger 2
@Singleton
@Component(
modules = [
WeatherRepositoryModule::class,
]
)
interface AppComponent
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Dagger 2
@Singleton
@Component(
modules = [
WeatherRepositoryModule::class,
]
)
interface AppComponent
val appComponent = DaggerAppComponent.create()
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Dagger 2
@Singleton
@Component(
modules = [
WeatherRepositoryModule::class,
]
)
interface AppComponent {
fun weatherRepository(): WeatherRepository
}
val appComponent = DaggerAppComponent.create()
val weatherRepository = appComponent.weatherRepository()
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Dagger 2
@Singleton
@Component(
modules = [
WeatherRepositoryModule::class,
]
)
interface AppComponent {
fun weatherRepository(): WeatherRepository
}
val appComponent = DaggerAppComponent.create()
val weatherRepository = appComponent.weatherRepository()
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Dagger 2
class WeatherRepositoryImpl(
client: HttpClient,
) : WeatherRepository {
...
}
@Module
object WeatherRepositoryModule {
@Provides
@Singleton
fun provideWeatherRepository(client: HttpClient): WeatherRepository {
return WeatherRepositoryImpl(client)
}
}
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Dagger 2
@Singleton
class WeatherRepositoryImpl @Inject constructor(
client: HttpClient,
) : WeatherRepository
@Module
object WeatherRepositoryModule {
@Provides
@Singleton
fun provideWeatherRepository(client: HttpClient): WeatherRepository {
return WeatherRepositoryImpl(client)
}
}
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Dagger 2
@Singleton
class WeatherRepositoryImpl @Inject constructor(
client: HttpClient,
) : WeatherRepository
@Module
object WeatherRepositoryModule {
@Provides
@Singleton
fun provideWeatherRepository(client: HttpClient): WeatherRepository {
return WeatherRepositoryImpl(client)
}
}
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Dagger 2
@Singleton
class WeatherRepositoryImpl @Inject constructor(
client: HttpClient,
) : WeatherRepository
@Module
interface WeatherRepositoryModule {
@Binds
fun bindWeatherRepository(
weatherRepositoryImpl: WeatherRepositoryImpl
): WeatherRepository
}
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Dagger 2
:app
AppComponent
:weather
WeatherRepositoryModule
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Dagger 2
:app
AppComponent
:weather
WeatherRepositoryModule
:forecast
appComponent.weatherRepository()
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Dagger 2
:app
AppComponent
:weather
WeatherRepositoryModule
:forecast
appComponent.weatherRepository()
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Dagger 2
@Singleton
@Component(
modules = [
WeatherRepositoryModule::class,
]
)
interface AppComponent {
fun weatherRepository(): WeatherRepository
}
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Dagger 2
interface WeatherComponent {
fun weatherRepository(): WeatherRepository
}
@Singleton
@Component(
modules = [
WeatherRepositoryModule::class,
]
)
interface AppComponent : WeatherComponent
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Dagger 2
:app
AppComponent
:weather
WeatherRepositoryModule
:forecast
appComponent.weatherRepository()
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Dagger 2
:app
AppComponent
:weather
WeatherRepositoryModule
:forecast
WeatherComponent
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Anvil
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Anvil
https://ralf-wondratschek.com/presentations
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Anvil
object AppScope
@Contributes*(AppScope::class)
@MergeComponent(AppScope::class)
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Dagger 2
@Singleton
class WeatherRepositoryImpl @Inject constructor(
client: HttpClient,
) : WeatherRepository
@Module
interface WeatherRepositoryModule {
@Binds
fun bindWeatherRepository(
weatherRepositoryImpl: WeatherRepositoryImpl
): WeatherRepository
}
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Anvil
@Singleton
class WeatherRepositoryImpl @Inject constructor(
client: HttpClient,
) : WeatherRepository
@Module
@ContributesTo(AppScope::class)
interface WeatherRepositoryModule {
@Binds
fun bindWeatherRepository(
weatherRepositoryImpl: WeatherRepositoryImpl
): WeatherRepository
}
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Anvil
@Singleton
@ContributesBinding(AppScope::class)
class WeatherRepositoryImpl @Inject constructor(
client: HttpClient,
) : WeatherRepository
@Module
@ContributesTo(AppScope::class)
interface WeatherRepositoryModule {
@Binds
fun bindWeatherRepository(
weatherRepositoryImpl: WeatherRepositoryImpl
): WeatherRepository
}
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Anvil
@Singleton
@ContributesBinding(AppScope::class)
class WeatherRepositoryImpl @Inject constructor(
client: HttpClient,
) : WeatherRepository
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Dagger 2
interface WeatherComponent {
fun weatherRepository(): WeatherRepository
}
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Anvil
@ContributesTo(AppScope::class)
interface WeatherComponent {
fun weatherRepository(): WeatherRepository
}
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Dagger 2
@Singleton
@Component(
modules = [
WeatherRepositoryModule::class,
]
)
interface AppComponent : WeatherComponent
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Anvil
@Singleton
@MergeComponent(
scope = AppScope::class,
modules = [
WeatherRepositoryModule::class,
]
)
interface AppComponent : WeatherComponent
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Anvil
@Singleton
@MergeComponent(
scope = AppScope::class,
)
interface AppComponent : WeatherComponent
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Anvil
@Singleton
@MergeComponent(AppScope::class)
interface AppComponent : WeatherComponent
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Anvil
@Singleton
@MergeComponent(AppScope::class)
interface AppComponent
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Anvil - Other benefits
● Removes boilerplate
● Improves build times significantly
● Easy to replace bindings in tests
● Extensible with custom code generators
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kotlin-inject
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“The Dagger 2 for Kotlin Multiplatform.”
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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, …
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kotlin-inject
import me.tatarka.inject.annotations.*
@Scope
annotation class Singleton
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Dagger 2
@Singleton
class WeatherRepositoryImpl @Inject constructor(
client: HttpClient,
) : WeatherRepository
@Module
interface WeatherRepositoryModule {
@Binds
fun bindWeatherRepository(
weatherRepositoryImpl: WeatherRepositoryImpl
): WeatherRepository
}
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kotlin-inject
@Singleton
@Inject
class WeatherRepositoryImpl(
client: HttpClient,
) : WeatherRepository
@Module
interface WeatherRepositoryModule {
@Binds
fun bindWeatherRepository(
weatherRepositoryImpl: WeatherRepositoryImpl
): WeatherRepository
}
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kotlin-inject
@Singleton
@Inject
class WeatherRepositoryImpl(
client: HttpClient,
) : WeatherRepository
@Module
interface WeatherRepositoryModule {
@Binds
fun bindWeatherRepository(
weatherRepositoryImpl: WeatherRepositoryImpl
): WeatherRepository
}
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kotlin-inject
@Singleton
@Inject
class WeatherRepositoryImpl(
client: HttpClient,
) : WeatherRepository
interface WeatherRepositoryComponent {
@Provides
fun provideWeatherRepository(
weatherRepository: WeatherRepositoryImpl
): WeatherRepository = weatherRepository
}
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kotlin-inject
@Provides
fun provideWeatherRepository(
weatherRepository: WeatherRepositoryImpl
): WeatherRepository = weatherRepository
val WeatherRepositoryImpl.bind: WeatherRepository
@Provides get() = this
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Dagger 2
@Singleton
@Component(
modules = [
WeatherRepositoryModule::class,
]
)
interface AppComponent
val appComponent = DaggerAppComponent.create()
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kotlin-inject
@Singleton
@Component
interface AppComponent : WeatherRepositoryComponent
val appComponent = DaggerAppComponent.create()
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kotlin-inject
@Singleton
@Component
interface AppComponent : WeatherRepositoryComponent
val appComponent = DaggerAppComponent.create()
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kotlin-inject
@Singleton
@Component
interface AppComponent : WeatherRepositoryComponent
val appComponent = AppComponent::class.create()
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kotlin-inject
@Singleton
@Component
interface AppComponent : WeatherRepositoryComponent {
val weatherRepository: WeatherRepository
}
val appComponent = AppComponent::class.create()
val weatherRepository = appComponent.weatherRepository
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kotlin-inject
@Singleton
@Component
interface AppComponent : WeatherRepositoryComponent {
val weatherRepository: WeatherRepository
}
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kotlin-inject
interface WeatherComponent {
val weatherRepository: WeatherRepository
}
@Singleton
@Component
interface AppComponent : WeatherRepositoryComponent, WeatherComponent
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kotlin-inject
:app
AppComponent
:weather
WeatherRepositoryComponent
:forecast
WeatherComponent
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kotlin-inject - the good
Reduced API surface:
Member injection
@Binds
@BindsInstance
@Module
@Subcomponent
@Assisted
@AssistedInject
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kotlin-inject - the good
Arguments:
@Component
abstract class AppComponent
val appComponent = AppComponent::class.create()
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kotlin-inject - the good
Arguments:
@Component
abstract class AppComponent(
@get:Provides val application: Application,
)
val application = …
val appComponent = AppComponent::class.create(application)
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kotlin-inject - the good
Component inheritance:
@Component
abstract class AppComponent
@Component
abstract class LoggedInComponent(
@get:Provides val user: User,
)
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kotlin-inject - the good
Component inheritance:
@Component
abstract class AppComponent
@Component
abstract class LoggedInComponent(
@Component val appComponent: AppComponent,
@get:Provides val user: User,
)
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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)
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kotlin-inject - the good
Override functions
@Component
abstract class AppComponent
@Component
abstract class LoggedInComponent(...)
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kotlin-inject - the good
Override functions
@Component
abstract class AppComponent
@Component
abstract class LoggedInComponent(...) {
interface Factory {
fun loggedInComponent(user: User): LoggedInComponent
}
}
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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
}
}
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kotlin-inject - the good
Kotlin support
Lazy, default arguments, assisted injection, overridden functions, …
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kotlin-inject - the good
Kotlin support
Lazy, default arguments, assisted injection, overridden functions, …
val viewModels: Map, @JvmSuppressWildcards Provider>
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kotlin-inject - the good
Kotlin support
Lazy, default arguments, assisted injection, overridden functions, …
val viewModels: Map, @JvmSuppressWildcards Provider>
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kotlin-inject - the good
KAPT
Stub generation
(kotlinc)
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kotlin-inject - the good
KAPT
Stub generation
(kotlinc)
KAPT
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kotlin-inject - the good
KAPT
Stub generation
(kotlinc)
KAPT kotlinc
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kotlin-inject - the good
KAPT
Stub generation
(kotlinc)
KAPT kotlinc javac
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kotlin-inject - the good
KSP
KSP
(kotlinc)
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kotlin-inject - the good
KSP
KSP
(kotlinc)
kotlinc
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kotlin-inject - the bad
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kotlin-inject - the bad
Scopes
object AppScope
object LoggedInScope
@SingleIn(AppScope::class)
@SingleIn(LoggedInScope::class)
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kotlin-inject - the bad
Scopes
@SingleInAppScope
@SingleInLoggedInScope
…
https://github.com/evant/kotlin-inject/issues/377
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kotlin-inject - the bad
Qualifiers
@ForScope(AppScope::class)
@ForScope(LoggedInScope::class)
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kotlin-inject - the bad
Qualifiers
typealias AppScopeCoroutineScope = CoroutineScope
typealias LoggedInScopeCoroutineScope = CoroutineScope
typealias PresenterCoroutineScope = CoroutineScope
…
https://github.com/evant/kotlin-inject/issues/253
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kotlin-inject - the bad
No wide adoption
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kotlin-inject - best practices
:app1
AppComponent, LoggedInComponent
:weather
WeatherRepositoryModule
:forecast
WeatherComponent
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kotlin-inject - best practices
:app1
AppComponent, LoggedInComponent
:weather
WeatherRepositoryModule
:forecast
WeatherComponent
:app2
AppComponent, LoggedInComponent
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kotlin-inject - best practices
:app1
AppComponent, LoggedInComponent
:weather
WeatherRepositoryModule
:forecast
WeatherComponent
:app2
AppComponent, LoggedInComponent
:app3
AppComponent, LoggedInComponent
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kotlin-inject - best practices
Scopes:
@Inject
@Singleton
class WeatherRepositoryImpl(
client: HttpClient,
) : WeatherRepository
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kotlin-inject - best practices
Naming:
interface WeatherRepositoryComponent {
val weatherRepository: WeatherRepository
@Provides
fun provideWeatherRepository(
weatherRepository: WeatherRepositoryImpl
): WeatherRepository = weatherRepository
}
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kotlin-inject - best practices
Naming:
interface ${descriptiveName}Component {
val weatherRepository: WeatherRepository
@Provides
fun provide${returnType}(
weatherRepository: WeatherRepositoryImpl
): WeatherRepository = weatherRepository
}
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kotlin-inject - best practices
Naming:
interface ${descriptiveName}Component {
val weatherRepository: WeatherRepository
@Provides
fun provide${returnType}(
weatherRepository: WeatherRepositoryImpl
): WeatherRepository = weatherRepository
}
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kotlin-inject - best practices
Component interfaces as inner classes:
abstract class ViewRenderer : Renderer {
fun init(...) {
val coroutineScope = CoroutineScope(
rootScopeProvider.rootScope.diComponent().dispatcher + Job(),
)
}
interface Component {
val dispatcher: MainCoroutineDispatcher
}
}
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kotlin-inject - best practices
Component interfaces as inner classes:
abstract class ViewRenderer : Renderer {
fun init(...) {
val coroutineScope = CoroutineScope(
rootScopeProvider.rootScope.diComponent().dispatcher + Job(),
)
}
interface Component {
val dispatcher: MainCoroutineDispatcher
}
}
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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)
}
}
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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)
}
}
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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)
}
}
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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)
}
}
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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)
}
}
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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
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kotlin-inject - best practices
iOS
@Component
abstract class IosAppComponent(
@get:Provides val iosNativeImplementations: IosNativeImplementations,
) : IosNativeImplementations.Component
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kotlin-inject - best practices
iOS
interface IosNativeImplementations {
val uiApplication: UIApplication
interface Component {
@Provides
fun provideUiApplication(
iosNativeImplementations: IosNativeImplementations
): UIApplication = iosNativeImplementations.uiApplication
}
}
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kotlin-inject - boilerplate
@Component
abstract class AppComponent(...)
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kotlin-inject - boilerplate
@Component
abstract class AppComponent(...) :
Component1
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kotlin-inject - boilerplate
@Component
abstract class AppComponent(...) :
Component1,
Component2
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kotlin-inject - boilerplate
@Component
abstract class AppComponent(...) :
Component1,
Component2,
Component3
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kotlin-inject - boilerplate
@Component
abstract class AppComponent(...) :
Component1,
Component2,
Component3,
Component4
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kotlin-inject - boilerplate
@Component
abstract class AppComponent(...) :
Component1,
Component2,
Component3,
Component4,
Component5
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kotlin-inject - boilerplate
@Component
abstract class AppComponent(...) :
Component1,
Component2,
Component3,
Component4,
Component5,
Component6
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kotlin-inject - boilerplate
@Component
abstract class AppComponent(...) :
Component1,
Component2,
Component3,
Component4,
Component5,
Component6,
Component7
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kotlin-inject - boilerplate
@Component
abstract class AppComponent(...) :
Component1,
Component2,
Component3,
Component4,
Component5,
Component6,
Component7,
Component8
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kotlin-inject - boilerplate
@Component
abstract class AppComponent(...) :
Component1,
Component2,
Component3,
Component4,
Component5,
Component6,
Component7,
Component8,
Component9
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kotlin-inject - boilerplate
@Component
abstract class AppComponent(...) :
Component1,
Component2,
Component3,
Component4,
Component5,
Component6,
Component7,
Component8,
Component9,
…
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kotlin-inject - boilerplate
interface NewComponent { … }
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kotlin-inject - boilerplate
interface NewComponent { … }
@Component
abstract class AndroidApp1Component : NewComponent
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kotlin-inject - boilerplate
interface NewComponent { … }
@Component
abstract class AndroidApp1Component : NewComponent
@Component
abstract class AndroidApp2Component : NewComponent
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kotlin-inject - boilerplate
interface NewComponent { … }
@Component
abstract class AndroidApp1Component : NewComponent
@Component
abstract class AndroidApp2Component : NewComponent
@Component
abstract class DemoAppComponent : NewComponent
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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
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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
…
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kotlin-inject - boilerplate
@Provides
fun provideWeatherRepository(
weatherRepository: WeatherRepositoryImpl
): WeatherRepository = weatherRepository
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kotlin-inject - boilerplate
We really miss Anvil …
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KSP
● Supports KMP
● Supports multiple rounds
https://kotlinlang.org/docs/ksp-overview.html
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KSP
include ':runtime'
include ':compiler'
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KSP
// runtime/build.gradle
plugins {
id 'org.jetbrains.kotlin.multiplatform'
}
// runtime/src/commonMain/kotlin/…/YourAnnotation.kt
annotation class YourAnnotation
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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"
}
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KSP
// compiler/src/main/kotlin/…/YourSymbolProcessorProvider.kt
@AutoService(SymbolProcessorProvider::class)
class YourSymbolProcessorProvider : SymbolProcessorProvider {
override fun create(environment: SymbolProcessorEnvironment): SymbolProcessor {
return ...
}
}
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KSP
// compiler/src/main/kotlin/…/YourSymbolProcessor.kt
private class YourSymbolProcessor(
private val environment: SymbolProcessorEnvironment,
) : SymbolProcessor {
override fun process(resolver: Resolver): List {
return emptyList()
}
}
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KSP
environment.logger.error(message, symbol)
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KSP
environment.logger.error(message, symbol)
> SourceFile.kt:8: Contributed component interfaces must be public.
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kotlin-inject - Anvil
@Target(CLASS)
annotation class ContributesTo
@Target(CLASS)
annotation class MergeComponent
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kotlin-inject - Anvil
● Use the scope as connection between contribution and merging side
● Find all contributions for a scope
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kotlin-inject - Anvil
interface WeatherComponent {
val weatherRepository: WeatherRepository
}
@Singleton
@Component
interface AppComponent : WeatherComponent
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kotlin-inject - Anvil
interface WeatherComponent {
val weatherRepository: WeatherRepository
}
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kotlin-inject - Anvil
@ContributesTo
interface WeatherComponent {
val weatherRepository: WeatherRepository
}
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kotlin-inject - Anvil
@ContributesTo
@Singleton
interface WeatherComponent {
val weatherRepository: WeatherRepository
}
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kotlin-inject - Anvil
@Singleton
@Component
interface AppComponent
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kotlin-inject - Anvil
@Singleton
@Component
@MergeComponent
interface AppComponent
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kotlin-inject - Anvil
@Singleton
@Component
@MergeComponent
interface AppComponent : AppComponentMerged
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kotlin-inject - Anvil
private class MergeComponentProcessor : SymbolProcessor {
override fun process(resolver: Resolver): List {
val declarations = resolver.getDeclarationsFromPackage(…)
...
}
}
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kotlin-inject - Anvil
private class MergeComponentProcessor : SymbolProcessor {
override fun process(resolver: Resolver): List {
val declarations = resolver.getDeclarationsFromPackage(…)
...
}
}
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kotlin-inject - Anvil
@ContributesTo
interface Component1
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kotlin-inject - Anvil
@ContributesTo
interface Component1
@ContributesTo
interface Component2
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kotlin-inject - Anvil
@ContributesTo
interface Component1
@ContributesTo
interface Component2
@MergeComponent
interface AppComponent
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kotlin-inject - Anvil
@ContributesTo
interface Component1
@ContributesTo
interface Component2
@MergeComponent
interface AppComponent
interface AppComponentMerged :
Component1, Component2
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kotlin-inject - Anvil
@ContributesTo
interface Component1
@ContributesTo
interface Component2
@MergeComponent
interface AppComponent
interface AppComponentMerged :
Component1, Component2
@MergeComponent
interface AppComponent : AppComponentMerged
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kotlin-inject - Anvil
@ContributesTo
interface Component1
@ContributesTo
interface Component2
@MergeComponent
interface AppComponent
interface AppComponentMerged :
Component1, Component2
@MergeComponent
interface AppComponent : AppComponentMerged
Run kotlin-inject processor
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@ContributesTo
// Given
package com.amazon
@ContributesTo
@Singleton
interface WeatherComponent {
val weatherRepository: WeatherRepository
}
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@ContributesTo
// Given
package com.amazon
@ContributesTo
@Singleton
interface WeatherComponent {
val weatherRepository: WeatherRepository
}
// Generate
package anvil.lookup
@Singleton
interface ComAmazonWeatherComponent : WeatherComponent
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@ContributesTo
// Given
package com.amazon
@ContributesTo
@Singleton
interface WeatherComponent {
val weatherRepository: WeatherRepository
}
// Generate
package anvil.lookup
@Singleton
interface ComAmazonWeatherComponent : WeatherComponent
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@ContributesTo
// Given
package com.amazon
@ContributesTo
@Singleton
interface WeatherComponent {
val weatherRepository: WeatherRepository
}
// Generate
package anvil.lookup
@Singleton
interface ComAmazonWeatherComponent : WeatherComponent
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@ContributesTo
resolver
.getNewSymbolsWithAnnotation(ContributesTo::class)
.filterIsInstance()
.onEach {
checkIsInterface(it)
checkIsPublic(it)
}
.forEach {
generateComponentInterface(it)
}
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@ContributesTo
fun Resolver.getNewSymbolsWithAnnotation(annotation: KClass<*>): Sequence {
val newFiles = getNewFiles().toSet()
return getSymbolsWithAnnotation(annotation)
.filter { it.containingFile in newFiles }
}
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@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)
}
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@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)
}
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@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)
}
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@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)
}
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@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)
}
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@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
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@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() },
)
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@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(
"$LOOKUP_PACKAGE." +
canonicalName.split(".").joinToString(separator = "") { it.capitalize() },
)
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@ContributesTo
val generatedComponent = componentInterface.generatedComponent
internal val JvmCompilationResult.componentInterface: Class<*>
get() = classLoader.loadClass("com.amazon.test.ComponentInterface")
internal val Class<*>.generatedComponent: Class<*>
get() = classLoader.loadClass(
"$LOOKUP_PACKAGE." +
canonicalName.split(".").joinToString(separator = "") { it.capitalize() },
)
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@MergeComponent
// Given
package com.amazon
@Singleton
@Component
@MergeComponent
interface AppComponent : AppComponentMerged
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@MergeComponent
// Given
package com.amazon
@Singleton
@Component
@MergeComponent
interface AppComponent : AppComponentMerged
// Generate
package com.amazon
@Singleton
interface AppComponentMerged : ${contributedSuperTypes}
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@MergeComponent
// Given
package com.amazon
@Singleton
@Component
@MergeComponent
interface AppComponent : AppComponentMerged
// Generate
package com.amazon
@Singleton
interface AppComponentMerged : ${contributedSuperTypes}
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@MergeComponent
// Given
package com.amazon
@Singleton
@Component
@MergeComponent
interface AppComponent : AppComponentMerged
// Generate
package com.amazon
@Singleton
interface AppComponentMerged : ${contributedSuperTypes}
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@MergeComponent
val className = ClassName(
packageName = clazz.packageName.asString(),
simpleNames = listOf("${clazz.innerClassNames()}Merged"),
)
val scope = clazz.scope()
val componentInterfaces = resolver.getDeclarationsFromPackage(LOOKUP_PACKAGE)
.filterIsInstance()
.filter { it.scope().isSameAs(scope) }
.toList()
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@MergeComponent
val className = ClassName(
packageName = clazz.packageName.asString(),
simpleNames = listOf("${clazz.innerClassNames()}Merged"),
)
val scope = clazz.scope()
val componentInterfaces = resolver.getDeclarationsFromPackage(LOOKUP_PACKAGE)
.filterIsInstance()
.filter { it.scope().isSameAs(scope) }
.toList()
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@MergeComponent
val className = ClassName(
packageName = clazz.packageName.asString(),
simpleNames = listOf("${clazz.innerClassNames()}Merged"),
)
val scope = clazz.scope()
val componentInterfaces = resolver.getDeclarationsFromPackage(LOOKUP_PACKAGE)
.filterIsInstance()
.filter { it.scope().isSameAs(scope) }
.toList()
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@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 })
},
)
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@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 })
},
)
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@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 })
},
)
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kotlin-inject - Anvil
@ContributesBinding
@ContributesSubcomponent
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kotlin-inject
@Inject
@Singleton
class WeatherRepositoryImpl(
client: HttpClient,
) : WeatherRepository
interface WeatherRepositoryComponent {
@Provides
fun provideWeatherRepository(
weatherRepository: WeatherRepositoryImpl
): WeatherRepository = weatherRepository
}
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kotlin-inject - Anvil
@ContributesBinding
@Inject
@Singleton
class WeatherRepositoryImpl(
client: HttpClient,
) : WeatherRepository
interface WeatherRepositoryComponent {
@Provides
fun provideWeatherRepository(
weatherRepository: WeatherRepositoryImpl
): WeatherRepository = weatherRepository
}
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kotlin-inject - Anvil
@ContributesBinding
@Inject
@Singleton
class WeatherRepositoryImpl(
client: HttpClient,
) : WeatherRepository
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kotlin-inject
interface WeatherComponent {
val weatherRepository: WeatherRepository
}
@Singleton
@Component
interface AppComponent : WeatherRepositoryComponent, WeatherComponent
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kotlin-inject - Anvil
interface WeatherComponent {
val weatherRepository: WeatherRepository
}
@Singleton
@Component
interface AppComponent : WeatherComponent
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kotlin-inject - Anvil
@ContributesTo
@Singleton
interface WeatherComponent {
val weatherRepository: WeatherRepository
}
@Singleton
@Component
interface AppComponent
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kotlin-inject - Anvil
@ContributesTo
@Singleton
interface WeatherComponent {
val weatherRepository: WeatherRepository
}
@Singleton
@Component
@MergeComponent
interface AppComponent : AppComponentMerged
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kotlin-inject
https://github.com/evant/kotlin-inject/discussions/221
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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
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Extending kotlin-inject
for fun & profit
Ralf Wondratschek