Delegates for SharedPreferences(Copy paste usage) (Maybe add some other delegates for other types soon)

BasePreferencesDataSource.kt

import android.content.SharedPreferences
import kotlin.properties.ReadWriteProperty
import kotlin.reflect.KProperty

abstract class BasePreferencesDataSource {

  protected abstract val preferences : SharedPreferences

  protected class StringPrefProperty(private val key: String) : ReadWriteProperty<BasePreferencesDataSource, String> {

    override fun getValue(thisRef: BasePreferencesDataSource, property: KProperty<*>): String {
      return thisRef.preferences.getString(key, "")!!
    }

    override fun setValue(thisRef: BasePreferencesDataSource, property: KProperty<*>, value: String) {
      thisRef.preferences.edit().putString(key, value).apply()
    }
  }
}

PreferencesDataSource.kt

import android.content.Context
import android.content.SharedPreferences
import android.preference.PreferenceManager

class PreferencesDataSource(context: Context) : BasePreferencesDataSource() {

  override val preferences: SharedPreferences = PreferenceManager.getDefaultSharedPreferences(context)

  val aPreference by StringPrefProperty(PREF_SAMPLE_KEY)

  companion object {
    private const val PREF_SAMPLE_KEY = "sample_key"
  }
}

SampleClass.kt

class SampleClass(private val preferencesDataSource: PreferencesDataSource) {

  fun someMethod() {
    //some code
    val preference: String = preferencesDataSource.aPreference
  }
}