Computer scienceProgramming languagesKotlinObject-oriented programmingObject-oriented programming features

Building your own delegate

Building a delegate class in Kotlin

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Hey there! This problem might be a bit unpredictable, but give it a go and let us know how you do!

In Kotlin, consider the following code snippet:

class Example {  var p: String by Delegate("initialValue")}

. What is the correct way to build the Delegate class to successfully delegate the property p, initialize it with a provided value and store all the changes of this property in a list?

Select one option from the list

class Delegate(var initialValue: String) {
  private var value: String = initialValue
  operator fun getValue(thisRef: Any?, property: KProperty<*>): String {
    return value
  }

  operator fun setValue(thisRef: Any?, property: KProperty<*>, value: String) {
    this.value = value
  }
}

class Delegate {
  var value: String = ""
  operator fun getValue(thisRef: Any?, property: KProperty<*>): String {
    return value
  }

  operator fun setValue(thisRef: Any?, property: KProperty<*>, value: String) {
    this.value = value
  }
}

class Delegate(var initialValue: String) {
  private var values: MutableList<String> = mutableListOf(initialValue)
  operator fun getValue(thisRef: Any?, property: KProperty<*>): String {
    return values.last()
  }

  operator fun setValue(thisRef: Any?, property: KProperty<*>, value: String) {
    values.add(value)
  }
}

class Delegate(var initialValue: String) {
  var value: String = initialValue
  operator fun getValue(thisRef: Any?, property: KProperty<*>): String {
    return value
  }

  operator fun setValue(thisRef: Any?, property: KProperty<*>, value: String) {
    this.value = value
  }
}

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