TL;DR: Helpers don't help. They are a non-cohesive bunch of messy subroutines.

Problems

• Readability

• The Least surprise principle

• Bijection Fault

• Static methods

Solutions

• Find a suitable name.

• If the helper is a library, break all the services into different methods.

• Methods should always be fulfilled by objects. Static methods are another code smell.

• Avoid extracting the helpers to Anonymous Functions.

Sample Code

Wrong

object UserHelper {
    fun getFullName(user: User) =
        "${user.firstName} ${user.lastName}"

    fun getCategory(user: User) =
        if (user.points > 70) 'A' else 'B'
}

Notice static methods usage:

data class User(
    val firstName: String,
    val lastName: String,
    val points: Int
)

fun main() {
    val alice = User(
        firstName = "Alice",
        lastName = "Gray",
        points = 78
    )

    val fullName = UserHelper.getFullName(alice)
    val category = UserHelper.getCategory(alice)
}

Right

class FullNameFormatter(private val user: User) {
    val fullName: String
        get() = "${user.firstName} ${user.lastName}"
}

class CategoryCalculator(private val user: User) {
    val displayName: Char
        get() = if(user.points > 70) 'A' else 'B'
}

fun main() {
    val alice = User(
        firstName = "Alice",
        lastName = "Gray",
        points = 78
    )

    val fullName = FullNameFormatter(alice).fullName
    val category = CategoryCalculator(alice).displayName
}

Alternatively, we can make the former Helper stateless for reuse...

class FullNameFormatter {
    fun fullName(user: User): String =
        "${user.firstName} ${user.lastName}"
}

class CategoryCalculator {
    fun displayName(user: User): Char =
        if (user.points > 70) 'A' else 'B'
}

fun main() {
    val alice = User(
        firstName = "Alice",
        lastName = "Gray",
        points = 78
    )

    val fullName = FullNameFormatter().fullName(alice)
    val category = CategoryCalculator().displayName(alice)
}

Conclusion

This is a well-established cultural name and a legacy habit from structured programming.

Most developers are reluctant to let old habits go.

We must be aware of the damage these kinds of names are bringing us.

Credits

• Code Smell 22 - Helpers by Maxi Contieri