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androidkotlinandroid-lifecyclekoinkoin-scope

Koin's lifecycleScope vs activity.scope. Are they the same?


I'm learning Koin's Scope from https://github.com/InsertKoinIO/koin/blob/master/koin-projects/docs/reference/koin-android/scope.md

If I have a Koin module as below

val myModule =
    module {
        scope<MyActivity> { scoped { Presenter() } }
    }

In my activity, I could do this

class MyActivity : AppCompatActivity() {

    private val presenter by lazy {
        lifecycleScope.get<Presenter>(Presenter::class.java)
    }
    // ...
}

Or I could use this.scope where this is MyActivity object.

class MyActivity : AppCompatActivity() {

    private val presenter by lazy {
        this.scope.get<Presenter>(Presenter::class.java)
    }
    // ...
}

I tested they are the same. Are both the same, or different? If they are different, what are their differences?


Solution

  • Based on the code I traced, the lifecycleScope will automatically close upon ON_DESTROY

    So I trace from the lifecycleScope -> getOrCreateAndroidScope() -> createAndBindAndroidScope -> bindScope(scope) -> lifecycle.addObserver(ScopeObserver(event, this, scope))

    The codes are all shown below.

    val LifecycleOwner.lifecycleScope: Scope
        get() = getOrCreateAndroidScope()
    
    private fun LifecycleOwner.getOrCreateAndroidScope(): Scope {
        val scopeId = getScopeId()
        return getKoin().getScopeOrNull(scopeId) ?: createAndBindAndroidScope(scopeId, getScopeName())
    }
    
    private fun LifecycleOwner.createAndBindAndroidScope(scopeId: String, qualifier: Qualifier): Scope {
        val scope = getKoin().createScope(scopeId, qualifier, this)
        bindScope(scope)
        return scope
    }
    
    fun LifecycleOwner.bindScope(scope: Scope, event: Lifecycle.Event = Lifecycle.Event.ON_DESTROY) {
        lifecycle.addObserver(ScopeObserver(event, this, scope))
    }
    
    class ScopeObserver(val event: Lifecycle.Event, val target: Any, val scope: Scope) :
        LifecycleObserver, KoinComponent {
    
        /**
         * Handle ON_STOP to release Koin modules
         */
        @OnLifecycleEvent(Lifecycle.Event.ON_STOP)
        fun onStop() {
            if (event == Lifecycle.Event.ON_STOP) {
                scope.close()
            }
        }
    
        /**
         * Handle ON_DESTROY to release Koin modules
         */
        @OnLifecycleEvent(Lifecycle.Event.ON_DESTROY)
        fun onDestroy() {
            if (event == Lifecycle.Event.ON_DESTROY) {
                scope.close()
            }
        }
    }