Hi Everybody! .. I'm just doing my first steps in ...

# getting-started

[Juan B]

Hi Everybody! .. I'm just doing my first steps in Kotlin after a long time using Groovy, so far I'm enjoying it. I have a question, probably simple but Im trying to get some traction.

❓ -> If I have an app which is using BigDecimal heavily, is there a way to avoid creating theBigDecimal explicitly when calling methods that expect a BigDecimal? (something like implicit transformation from integer to BigDecimal on the caller so you can call methods using just a integer)

E.g. When instantiating this data class, I have to pass the salary as explicit integer:

val employeeRunData = EmployeeRunData(annualSalary = BigDecimal(120000))

Instead, I would like to do something like: <note there is not call to _BigDecimal(120000)_>

val employeeRunData = EmployeeRunData(annualSalary = 120000))

I would highlight that the annoyance is while writing unit test. Thank you all!

[Milan Hruban]

there is no implicit conversion, but you can always do

fun EmployeeRunData(annualSalary: Int) = EmployeeRunData(annualSalary = BigDecimal(annualSalary))

[Michael de Kaste]

secondary constructors are probably what you need:

fun main(){
    val constructWithBigDecimal = EmployeeRunData(BigDecimal.TEN)
    val constructWithNumber = EmployeeRunData(2341L)
}

data class EmployeeRunData(val annualSalary: BigDecimal) {
    constructor(annualSalary: Number) : this(BigDecimal(annualSalary.toString()))
}

This way, whenever you call the constructor of EmployeeRunData, it will set its annualSalary directly if you call it with a BigDecimal, otherwise it will call it with the constructor.

If your problem is in writing unittests only, I suggest just making local functions

[Martin]

previously, in another language, I used extension methods to make this a bit easier. So if foo() expects a BigDecimal, you could call it like foo(<http://123.bd|123.bd>)

[elizarov]

➕ That’s what I’d recommend:

val <http://Int.bd|Int.bd> get() = toBigDecimal()

[Juan B]

Thanks all for the answers. I’m trying to avoid secondary constructors because I want the production contract to be only with BigDecimal.

I think that @Martin and @elizarov answers are what I’m looking for. Roman/Martin Could you provide some context/explanation to help me to understand the solution? ; my initial read from this is that we are creating a extension function to a property called “bd” that call a method toBigDecimal() which needs to be implemented. Is it correct?

Thanks for the help!

[Martin]

The Kotlin standard library already defines toBigDecimal() as an extension function on the Int type, so you don't need to implement that. @elizarov's solution is adding a bd property to the Int type, and the getter for that property delegates to toBigDecimal(). That way, EmployeeRunData only needs the primary constructor, which takes a BigDecimal, and you can call it like: val constructWithBigDecimal = EmployeeRunData(<http://10.bd|10.bd>). Does that make more sense?

[Juan B]

Thanks a lot @Martin . It makes sense!!