Is it possible to maker a mapping extension functi...

# announcements

[Paul Dhaliwal]

Is it possible to maker a mapping extension function which will convert the Type of an object. For example, I have a Results sealed class and within it different data classes for different results:

sealed class Result<out T : Any?> {
    data class Success<out T : Any>(val data: T) : Result<T>()
    data class Unauthorized(val exception: Exception) : Result<Nothing>()
    data class Timeout(val exception: Exception) : Result<Nothing>()
    data class Error(val exception: Exception) : Result<Nothing>()
}

and I’d like to make a mapping extension function like so Result<EntityModel>.toDomain(DomainModel) which would output Result<DomainModel>.
So if the object was Success<UserEntityModel> it would return Success<UserDomainModel>

[Kroppeb]

What should the function return if called on Error?

[Kirill Zhukov]

Sounds like you want a simple mapper

[Kirill Zhukov]

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[Joan Colmenero]

@Kirill Zhukov but then if I do something like @GET("/") suspend fun pew(whatever) : Result<PJO> then in my repositoryImpl for instance how do I say if it's a Result.Success or a Result.Error?

[Paul Dhaliwal]

@Kirill Zhukov Ah I think I understand the concept, though I’m still confused by generics. In this case since my mapper functions are extension functions would this not work? I can certainly get around this by making specific mappers for each Result<Type> however I was hoping to find a more generic solution. I’m sure it’s a great solution but not sure I fully understand it.

[Kirill Zhukov]

My example only applies the mapper to the successful result, you can as well rename the mapper onSuccess and add onFailure.

[Kirill Zhukov]

What part about generics is confusing?

[Paul Dhaliwal]

I’m still a relative beginner to programming and honsetly have learnt much about them. I’ll read more about them and then come back to this solution