Prototype Design Pattern in Kotlin

1. Definition

The Prototype Design Pattern involves creating objects by copying an existing object, known as the prototype, instead of creating new instances from scratch. This can be especially useful when the instantiation process is resource-intensive or complex.

2. Problem Statement

When creating instances of a class is more expensive (in terms of time or resources) or requires more setup than simply copying an existing instance, how can we optimize this process?

3. Solution

The Prototype pattern allows you to clone an existing object and modify it to meet your needs, instead of going through the laborious process of creating a new one from scratch. This pattern leverages Kotlin's ability to clone objects with the copy function when working with data classes.

4. Real-World Use Cases

1. In graphics editors, objects can be cloned and modifications can be applied to the duplicate without affecting the original.

2. Prototyping tools where different versions of an object need to be created from a baseline model.

3. In games, to replicate existing game objects with slight differences.

5. Implementation Steps

1. Create a prototype interface that declares the cloning method.

2. Implement the prototype interface in concrete classes.

3. Use the copy function to clone objects and make necessary changes to the cloned object.

6. Implementation in Kotlin

// Step 1: Prototype Interface
interface Prototype {
    fun clone(): Prototype

// Step 2: Concrete Implementation
data class Person(val name: String, val age: Int) : Prototype {
    override fun clone(): Person {
        return this.copy()

fun main() {
    // Original object
    val originalPerson = Person("John", 30)

    // Clone object and modify
    val clonedPerson = originalPerson.clone().copy(name = "Jane")

    println("Original: $originalPerson")
    println("Cloned: $clonedPerson")


Original: Person(name=John, age=30)
Cloned: Person(name=Jane, age=30)


1. We have a simple Prototype interface that declares a clone method.

2. The Person data class implements this interface. Since it's a data class, Kotlin automatically provides a copy function for it. We use this to implement the clone method.

3. In the main function, we create an original Person instance. We then clone this original and modify the name for the cloned version.

4. The output shows the original and the cloned objects, with the latter having a modified name.

7. When to use?

The Prototype Pattern is beneficial when:

1. Objects have numerous shared configurations but differ in a few parameters.

2. Creating a new instance of a class is more resource-intensive than copying an existing one.

3. You want to keep the number of classes in a system to a minimum, especially when dealing with numerous small objects that differ slightly in state.

This pattern can be a great way to improve performance in situations where object creation is a bottleneck.