Base Activity/Fragment that enables composition within the Activity/Fragment lifecycle

CompositionActivity.kt

import android.app.Activity
import android.content.Intent
import android.os.Bundle
import android.support.v7.app.AppCompatActivity

abstract class CompositionActivity : AppCompatActivity() {

    private val onCreateFeatures = mutableListOf<CompositionActivity.OnCreateFeature>()
    private val onStartFeatures = mutableListOf<CompositionActivity.OnStartFeature>()
    private val onResumeFeatures = mutableListOf<CompositionActivity.OnResumeFeature>()
    private val onPauseFeatures = mutableListOf<CompositionActivity.OnPauseFeature>()
    private val onStopFeatures = mutableListOf<CompositionActivity.OnStopFeature>()
    private val onRestartFeatures = mutableListOf<CompositionActivity.OnRestartFeature>()
    private val onDestroyFeatures = mutableListOf<CompositionActivity.OnDestroyFeature>()
    private val onActivityResultFeatures = mutableListOf<CompositionActivity.OnActivityResultFeature>()

    protected fun addFeature(feature: CompositionFeature) {
        if (feature is CompositionActivity.OnCreateFeature) onCreateFeatures.add(feature)
        if (feature is CompositionActivity.OnStartFeature) onStartFeatures.add(feature)
        if (feature is CompositionActivity.OnResumeFeature) onResumeFeatures.add(feature)
        if (feature is CompositionActivity.OnPauseFeature) onPauseFeatures.add(feature)
        if (feature is CompositionActivity.OnStopFeature) onStopFeatures.add(feature)
        if (feature is CompositionActivity.OnRestartFeature) onRestartFeatures.add(feature)
        if (feature is CompositionActivity.OnDestroyFeature) onDestroyFeatures.add(feature)
        if (feature is CompositionActivity.OnActivityResultFeature) onActivityResultFeatures.add(feature)
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        onCreateFeatures.forEach { it.onCreate(this, savedInstanceState) }
    }

    override fun onStart() {
        super.onStart()
        onStartFeatures.forEach { it.onStart(this) }
    }

    override fun onResume() {
        super.onResume()
        onResumeFeatures.forEach { it.onResume(this) }
    }

    override fun onPause() {
        super.onPause()
        onPauseFeatures.forEach { it.onPause(this) }
    }

    override fun onStop() {
        super.onStop()
        onStopFeatures.forEach { it.onStop(this) }
    }

    override fun onRestart() {
        super.onRestart()
        onRestartFeatures.forEach { it.onRestart(this) }
    }

    override fun onDestroy() {
        super.onDestroy()
        onDestroyFeatures.forEach { it.onDestroy(this) }
    }

    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)
        onActivityResultFeatures.forEach { it.onActivityResult(this, requestCode, resultCode, data) }
    }

    interface OnCreateFeature : CompositionFeature {
        fun onCreate(activity: Activity, savedInstanceState: Bundle?)
    }

    interface OnStartFeature : CompositionFeature {
        fun onStart(activity: Activity)
    }

    interface OnResumeFeature : CompositionFeature {
        fun onResume(activity: Activity)
    }

    interface OnPauseFeature : CompositionFeature {
        fun onPause(activity: Activity)
    }

    interface OnStopFeature : CompositionFeature {
        fun onStop(activity: Activity)
    }

    interface OnRestartFeature : CompositionFeature {
        fun onRestart(activity: Activity)
    }

    interface OnDestroyFeature : CompositionFeature {
        fun onDestroy(activity: Activity)
    }

    interface OnActivityResultFeature : CompositionFeature {
        fun onActivityResult(activity: Activity, requestCode: Int, resultCode: Int, data: Intent?)
    }
}

CompositionFeature.kt

interface CompositionFeature

CompositionFragment.kt

import android.content.Context
import android.content.Intent
import android.os.Bundle
import android.support.v4.app.Fragment

abstract class CompositionFragment : Fragment() {

    private val onAttachFeatures = mutableListOf<CompositionFragment.OnAttachFeature>()
    private val onCreateFeatures = mutableListOf<CompositionFragment.OnCreateFeature>()
    private val onActivityCreatedFeatures = mutableListOf<CompositionFragment.OnActivityCreatedFeature>()
    private val onStartFeatures = mutableListOf<CompositionFragment.OnStartFeature>()
    private val onResumeFeatures = mutableListOf<CompositionFragment.OnResumeFeature>()
    private val onPauseFeatures = mutableListOf<CompositionFragment.OnPauseFeature>()
    private val onStopFeatures = mutableListOf<CompositionFragment.OnStopFeature>()
    private val onDestroyFeatures = mutableListOf<CompositionFragment.OnDestroyFeature>()
    private val onDetachFeatures = mutableListOf<CompositionFragment.OnDetachFeature>()
    private val onActivityResultFeatures = mutableListOf<CompositionFragment.OnActivityResultFeature>()

    protected fun addFeature(feature: CompositionFeature) {
        if (feature is CompositionFragment.OnAttachFeature) onAttachFeatures.add(feature)
        if (feature is CompositionFragment.OnCreateFeature) onCreateFeatures.add(feature)
        if (feature is CompositionFragment.OnActivityCreatedFeature) onActivityCreatedFeatures.add(feature)
        if (feature is CompositionFragment.OnStartFeature) onStartFeatures.add(feature)
        if (feature is CompositionFragment.OnResumeFeature) onResumeFeatures.add(feature)
        if (feature is CompositionFragment.OnPauseFeature) onPauseFeatures.add(feature)
        if (feature is CompositionFragment.OnStopFeature) onStopFeatures.add(feature)
        if (feature is CompositionFragment.OnDestroyFeature) onDestroyFeatures.add(feature)
        if (feature is CompositionFragment.OnDetachFeature) onDetachFeatures.add(feature)
        if (feature is CompositionFragment.OnActivityResultFeature) onActivityResultFeatures.add(feature)

    }

    override fun onAttach(context: Context?) {
        super.onAttach(context)
        onAttachFeatures.forEach { it.onAttach(this, context) }
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        onCreateFeatures.forEach { it.onCreate(this, savedInstanceState) }
    }

    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)
        onActivityCreatedFeatures.forEach { it.onActivityCreated(this, savedInstanceState) }
    }

    override fun onStart() {
        super.onStart()
        onStartFeatures.map { it.onStart(this) }
    }

    override fun onResume() {
        super.onResume()
        onResumeFeatures.map { it.onResume(this) }
    }

    override fun onPause() {
        super.onPause()
        onPauseFeatures.forEach { it.onPause(this) }
    }

    override fun onStop() {
        super.onStop()
        onStopFeatures.forEach { it.onStop(this) }
    }

    override fun onDestroy() {
        super.onDestroy()
        onDestroyFeatures.forEach { it.onDestroy(this) }
    }

    override fun onDetach() {
        super.onDetach()
        onDetachFeatures.forEach { it.onDetach(this) }
    }

    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)
        onActivityResultFeatures.forEach { it.onActivityResult(this, requestCode, resultCode, data) }
    }

    interface OnAttachFeature : CompositionFeature {
        fun onAttach(fragment: Fragment, context: Context?)

    }

    interface OnCreateFeature : CompositionFeature {
        fun onCreate(fragment: Fragment, savedInstanceState: Bundle?)

    }

    interface OnActivityCreatedFeature : CompositionFeature {
        fun onActivityCreated(fragment: Fragment, savedInstanceState: Bundle?)

    }

    interface OnStartFeature : CompositionFeature {
        fun onStart(fragment: Fragment)

    }

    interface OnResumeFeature : CompositionFeature {
        fun onResume(fragment: Fragment)

    }

    interface OnPauseFeature : CompositionFeature {
        fun onPause(fragment: Fragment)

    }

    interface OnStopFeature : CompositionFeature {
        fun onStop(fragment: Fragment)

    }

    interface OnDestroyFeature : CompositionFeature {
        fun onDestroy(fragment: Fragment)

    }

    interface OnDetachFeature : CompositionFeature {
        fun onDetach(fragment: Fragment)
    }

    interface OnActivityResultFeature : CompositionFeature {
        fun onActivityResult(fragment: Fragment, requestCode: Int, resultCode: Int, data: Intent?)
    }
}