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Lazy Modules and Background Loading

In this section we will see how to organize your modules with lazy loading approach.

Defining Lazy Modules [Experimental]​

You can now declare lazy Koin module, to avoid trigger any pre allocation of resources and load them in background with Koin start.

  • lazyModule - declare a Lazy Kotlin version of Koin Module
  • Module.includes - allow to include lazy Modules

A good example is always better to understand:

// Some lazy modules
val m2 = lazyModule {
    singleOf(::ClassB)
}

// include m2 lazy module
val m1 = lazyModule {
    includes(m2)
    singleOf(::ClassA) { bind<IClassA>() }
}
info
LazyModule won't trigger any resources until it has been loaded by the following API

Background loading with Kotlin coroutines [Experimental]​

Once you have declared some lazy modules, you can load them in background from your Koin configuration and further more.

  • KoinApplication.lazyModules - load lazy modules in background with coroutines, regarding platform default Dispatchers
  • Koin.waitAllStartJobs - wait for start jobs to complete
  • Koin.runOnKoinStarted - run block code after start completion

A good example is always better to understand:

startKoin {
    // load lazy Modules in background
    lazyModules(m1)
}

val koin = KoinPlatform.getKoin()

// wait for loading jobs to finish
koin.waitAllStartJobs()

// or run code after loading is done
koin.runOnKoinStarted { koin ->
    // run after background load complete
}
note
The `lazyModules` function allow you to specify a dispatcher: `lazyModules(modules, dispatcher = Dispatcher.IO)`
info
Default dispatcher for coroutines engine is `Dispatchers.Default`

Limitation - Mixing Modules/Lazy Modules​

For now we advise to avoid mixing modules & lazy modules, in the startup. Avoid having mainModule requiring dependency in lazyReporter.

startKoin {
    androidLogger()
    androidContext(this@TestApp)
    modules(mainModule)
    lazyModules(lazyReporter)
}
danger

For now Koin doesn't check if your module depends on a lazy modules