Kotlin Code Smell 8 - Too Many Arguments

TL;DR: Avoid passing more than three arguments to your functions.

Problems

• Low maintainability.

• Low reusability.

• Coupling.

• Readability.

Solutions

• Identify cohesive relationships among arguments.

• Create a "context" or related group.

• Consider using the Method Object Pattern.

• Avoid using "basic" types such as strings, arrays, and integers, and instead think in terms of objects.

Exceptions

• Operations in the real world that do not require cohesive collaborators.

Sample Code

Wrong

class Printer {
    fun print(
        documentToPrint: String,
        paperSize: String,
        orientation: String,
        grayScales: Boolean,
        pageFrom: Int,
        pageTo: Int,
        copies: Int,
        marginLeft: Float,
        marginRight: Float,
        marginTop: Float,
        marginBottom: Float
    ): Unit = TODO()
}

Right

class PaperSize {
    //...
}

class Document {
    //...
}

class PrintMargins {
    //...
}

class PrintRange {
    //...
}

class ColorConfiguration {
    //...
}

class PrintOrientation {
    //...
}

class PrintSetup(
    paperSize: PaperSize,
    orientation: PrintOrientation,
    color: ColorConfiguration,
    range: PrintRange,
    copiesCount: Int,
    margins: PrintMargins
)

class Printer {
    fun print(
        documentToPrint: Document,
        setup: PrintSetup
    ): Unit = TODO()
}

Conclusion

To improve code quality, identify and group related arguments. Aim for real-world mappings and cohesive objects.

If a function requires too many arguments, some of them might be better suited for class construction. This is also a design issue.

More Info

• Refactoring Guru

Credits

• Code Smell 10 - Too Many Arguments by Maximiliano Contieri