Why scope functions reduce boilerplate in Kotlin - See It in Action

Why scope functions reduce boilerplate

📖 Scenario: Imagine you are organizing a small event and need to create and configure a Person object with several properties. Normally, you would write multiple lines to set each property. Kotlin's scope functions help reduce this repetitive code.

🎯 Goal: Learn how to use Kotlin's apply scope function to reduce boilerplate when setting multiple properties on an object.

📋 What You'll Learn

Create a Person class with name, age, and city properties

Create an instance of Person with default values

Use a variable called person to hold the instance

Use the apply scope function to set name, age, and city properties

Print the person details using println

💡 Why This Matters

🌍 Real World

When creating and configuring objects in apps, scope functions help write less repetitive code and keep your code clean.

💼 Career

Understanding scope functions is important for Kotlin developers to write efficient and readable code, a common requirement in Android and backend development.

1

Create the Person class and an instance

Create a Kotlin class called Person with mutable properties name (String), age (Int), and city (String). Then create a variable called person and assign it a new Person object with default values: empty string for name and city, and 0 for age.

Kotlin

class Person {
    var name: String = ""
    var age: Int = 0
    var city: String = ""
}

// Create a Person instance with default values
val person = Person()

Need a hint?

Define the class with var properties and create an instance with default values.

2

Add a configuration variable for new values

Create three variables: newName with value "Alice", newAge with value 30, and newCity with value "New York".

Kotlin

class Person {
    var name: String = ""
    var age: Int = 0
    var city: String = ""
}

val person = Person()

// Create variables for new values
val newName = "Alice"
val newAge = 30
val newCity = "New York"

Need a hint?

Just create three variables with the exact names and values.

3

Use apply to set properties with less code

Use the apply scope function on the person object to set its name to newName, age to newAge, and city to newCity. Assign the result back to person.

Kotlin

class Person {
    var name: String = ""
    var age: Int = 0
    var city: String = ""
}

val person = Person()

val newName = "Alice"
val newAge = 30
val newCity = "New York"

// Use apply to set properties
person = person.apply {
    // Your code here
}

Need a hint?

Inside apply, set each property using the variable names.

4

Print the person details

Write a println statement to print the person object's name, age, and city properties in this exact format: Name: Alice, Age: 30, City: New York.

Kotlin

class Person {
    var name: String = ""
    var age: Int = 0
    var city: String = ""
}

var person = Person()

val newName = "Alice"
val newAge = 30
val newCity = "New York"

person = person.apply {
    name = newName
    age = newAge
    city = newCity
}

// Print the person details
println("Name: ${person.name}, Age: ${person.age}, City: ${person.city}")

Need a hint?

Use string templates inside println to show the properties.