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A lazy property that gets cleaned up when the fragment's view is destroyed
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package be.digitalia.common.fragment | |
import android.view.View | |
import androidx.fragment.app.Fragment | |
import androidx.lifecycle.Lifecycle | |
import androidx.lifecycle.LifecycleEventObserver | |
import androidx.lifecycle.LifecycleOwner | |
/** | |
* A lazy property that gets cleaned up when the fragment's view is destroyed. | |
* | |
* Accessing this variable while the fragment's view is destroyed will throw IllegalStateException. | |
*/ | |
fun <T : Any> Fragment.viewLifecycleLazy(initializer: (View) -> T): Lazy<T> = | |
ViewLifecycleLazy(this, initializer) | |
private class ViewLifecycleLazy<T : Any>( | |
private val fragment: Fragment, | |
private val initializer: (View) -> T | |
) : Lazy<T>, LifecycleEventObserver { | |
private var cached: T? = null | |
override val value: T | |
get() { | |
return cached ?: run { | |
val newValue = initializer(fragment.requireView()) | |
cached = newValue | |
fragment.viewLifecycleOwner.lifecycle.addObserver(this) | |
newValue | |
} | |
} | |
override fun isInitialized() = cached != null | |
override fun toString() = cached.toString() | |
override fun onStateChanged(source: LifecycleOwner, event: Lifecycle.Event) { | |
if (event == Lifecycle.Event.ON_DESTROY) { | |
cached = null | |
} | |
} | |
} |
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