The apply function

The apply function is a scope function. Scope functions in the Kotlin standard library are designed to execute a block of code in the context of an object. When you call a scope function on an object using a lambda expression, it provides a temporary scope in which the object can be accessed without needing to refer to its name explicitly. There are five scope functions in Kotlin:

• let
• run
• with
• apply
• also

These functions are used for different purposes, but they all allow you to work more concisely and clearly with objects in Kotlin.

The apply function is an extension function that can be used with any object. It takes a block of code as an argument and returns the modified object after applying the block.

To explain apply, we are going to first create a new class, which we will call Book. As its name suggests, we are going to create a class that is the definition of a book. For now, we are not going to worry about...