Is anyone could help with this How to write an extensions fu kotlinlang #announcements

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Title

m

mike_shysh

11/06/2017, 1:57 PM

Is anyone could help with this: How to write an extensions function if data class is defined in .kt file, not in kotlin separate class

fun CustomerInfo.addRandomPartToName(): CustomerInfo {
    val oldItem = this.customerInfo <<<< `this` is not usable
    val newItem = oldItem?.copy(name = oldItem.name + RandomStringUtils.randomAlphabetic(7))
    return this.copy(customerInfo = newItem)
}

m

menegatti

11/06/2017, 2:01 PM

what’s the error message?

it seems to me that

oldItem

should be only

this

as that is the scope of your extension

m

mike_shysh

11/06/2017, 2:03 PM

Error:(27, 24) Kotlin: Unresolved reference: customerInfo

Error:(29, 22) Kotlin: Cannot find a parameter with this name: customerInfo

customerInfo

is red

val oldItem = this.customerInfo

this.copy(customerInfo = newItem)

m

menegatti

11/06/2017, 2:04 PM

the thing is

this

is already

CustomerInfo

m

mike_shysh

11/06/2017, 2:05 PM

oh sorry, my bad

yeah, data clases names were a bit messed up

m

menegatti

11/06/2017, 2:05 PM

this

will always be the instance of the type to which the extension belongs to

fun String.foo()  = this.append("a")

for instance

m

mike_shysh

11/06/2017, 2:06 PM

thanks, got it

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