I have some data transfer class which I want to share between platforms. There is only one difference. The implementations have different annotations on different platforms. What is the best way to do it? I know the only one way.
In the commonsMain:
expect class ErrorMessage (message: String = "") : DataTransferObject {
var message: String
}
In jvmMain:
@SomeJvmAnnotation
actual class ErrorMessage actual constructor (actual var message: String) : DataTransferObject
But if I implement every class this way than there is no profit from KMM. This way I need to implement every class n + 1 times where n is a number of platforms. Is there a simpler way to apply different annotations?
May be there is a way not to put expect on class.
Not the greatest solution, but you can use actual and expect to define your platform-specific annotations.
I used it to ignore unit tests only on the JS runtime.
commonMain
/**
* Ignore a test when running the test on a JavaScript test runtime.
*/
@Target( AnnotationTarget.CLASS, AnnotationTarget.FUNCTION )
expect annotation class JsIgnore()
jsMain
actual typealias JsIgnore = kotlin.test.Ignore
jvmMain
// Nothing to do. This should only ignore tests on the JavaScript test runtime.
actual annotation class JsIgnore
I guess whether or not this is appropriate for you will really depend on the specific annotations you need for each platform, and to which degree they semantically overlap.