what’s the cleanest/most kotlin-idiomatic way to define a method which can take one of 3 types of ob...

# announcements

[Andrew Ebling]

what’s the cleanest/most kotlin-idiomatic way to define a method which can take one of 3 types of object, short of declaring 4x separate methods? The types in question are Date, String, Bool and Int. Wondered about a sealed class unsure if this is the most appropriate approach.

[Big Chungus]

Overloading would be the cleanest approach

[Tomasz Krakowiak]

Depends... if you define some sort of "algebra" the cleanest would be to do generic function and pass the "algebra" as additional parameter or receiver.

Example:
Mathematical Order is a algebra, that is represented in Kotlin by Comparator interface.

Collection.sort function is sample method that receives this algebra.

[Tomasz Krakowiak]

sealed class / interface are idiomatic way for representing closed domains. I can't think of closed domain where Date, String, Bool and Int are only types that share the sematinc of such domain.

[Tomasz Krakowiak]

Overloading is the way to go if you just need to handle some common characteristic of those types internally in your implementation, but not in public API.

[Tomasz Krakowiak]

btw. Good topic for #C4GKV43N2

[CLOVIS]

Depending on your requirements, Arrow Meta (#CJ699L62W) has union types, that can be used exactly for this. I don't remember how stable these are though.

[Roukanken]

Imho this depends a lot on what exactly is the domain meaning of the attributes/functio - would have to specify thata bit more

eg, those attributes could be all different formats of specifying a date - then you would want function to accept a single argument of type X, but could construct X with 3 different ways - either own MyDate class with 3 constructors or extension parser functions Date.parse(String): Date & Date.parse(Int, Bool): Date

or it could be a function smth like setJsonAttribute(name: String, value: ???) - there it could be discussed between multiple overloads or sealed class JsonValue or maybe those union types

pretty sure I could think up more variants with different results... 😄

[Dmitry]

I agree that with @Big Chungus, that overloading would be cleanest approach in most cases.

Union types is way-to-go in such scenario, but not supported natively by kotlin.

Arrow Meta requires extra plugin. I personally try to avoid adding extra things to build pipeline. But If I would be user of Arrow libraries already, I would try Union type plugin.

[Andrew Ebling]

thanks everyone. I’ll start with method overrides I think.