What are scope functions in Kotlin? How to use them!!

Kotlin scope function ( let, run, with, apply, also )

Basically, these functions all perform the same action: execute a block of code on an object
When you call such a function on an object with a lambda expression provided, it forms a temporary scope. In this scope, you can access the object without its name.

How Scope functions differ

1-The way they refer to the context object ( this or it )
2-Return value ( return the context object. or return the lambda result.)

Note: Context object (a lambda receiver (this) , lambda argument (it) )

Explanation of each Scope function

Let

use case : Executing a lambda on non-nullable objects
use case : Introducing an expression as a variable in local scope

1-The context object is available as an argument (it).

2-The return value is the lambda result.

Example:

val numbers = mutableListOf("one", "two", "three", "four", "five")
val resultList = numbers.map { it.length }.filter { it > 3 }
println(resultList)


val numbers1 = listOf("one", "two", "three", "four")
val modifiedFirstItem = numbers1.first().let { firstItem ->
    println("The first item of the list is '$firstItem'")
    if (firstItem.length >= 5) firstItem else "!" + firstItem + "!"
}.uppercase()
println("First item after modifications: '$modifiedFirstItem'")

With

use case: Grouping function calls on an object


1-The context object is available as a receiver (this).

2-The return value is the lambda result.

Example:

val numbers2 = mutableListOf("one", "two", "three")
with(numbers2) {
    println("'with' is called with argument $this")

}

val numbers3 = mutableListOf("one", "two", "three")
val firstAndLast = with(numbers3) {
    "The first element is ${first()}," +
            " the last element is ${last()}"
}
println(firstAndLast)

Run

use case : Object configuration and computing the result

use case : Running statements where an expression is required: non-extension run

1-The context object is available as a receiver (this).

2-The return value is the lambda result.

Example:

val str = "Hello"
// this
str.run {
    println("The string's length: $length")
    //println("The string's length: ${this.length}") // does the same
}

Apply

use case : Object configuration
1-The context object is available as a receiver (this).

2-The return value is the object itself.

Example:
val adam = Person("Adam").apply {
   age = 32
   city = "London"
}
println(adam)
result : Person(name=Adam, age=32, city=London)

Also

use case: Additional effects

1-The context object is available as an argument (it).

2-The return value is the object itself.

val numbers4 = mutableListOf("one", "two", "three")
numbers4
    .also { println("The list elements before adding new one: $it") }
    .add("four")

Example credit:developer.android.com

Thank you…