kotlin "newishly" person Q given ```typealias RequestGroupingKey = Triple<String, String, String>``...

# getting-started

[Edward Muller]

kotlin "newishly" person Q

given

typealias RequestGroupingKey = Triple<String, String, String>

Which one of this is more lighter weight & more performant?

val RequestGroupingKey.thing: String
    get() = this.first

or

fun RequestGroupingKey.thing(): String = this.first

or is there something else I should be doing like a data class?

[Daniel Pitts]

[deleted] Revising my answer....

[Daniel Pitts]

You should almost definitely use a data class instead.

data class RequestGroupingKey(val thing: String, val ama: String, val bob:String)

gives you a better semantic type.

One of the downsides to what you wrote is that RequestGroupingKey is simply an alias for Triple<String, String, String>, which means anyone with any Triple<String, String, String> can call .thing on it. Which I'm assuming was not the intent.

[Edward Muller]

yeah, not really.

[Daniel Pitts]

Furthermore, both of the approaches you wrote are practically the same implementation, so you get no performance benefit from either one of them.

[Edward Muller]

👍

[Daniel Pitts]

Pretty much the only time I use typealias is for callback signatures:

typealias SomeEventListener = (SomeEvent)->Unit

[Daniel Pitts]

Even then, it's mostly useful only when the signature itself is more complex, and is used in many places.

[Arjan van Wieringen]

Honest question: which situations do you have that this actually matters?

[Daniel Pitts]

You mean typealiasing lambdas?

[Daniel Pitts]

Often when designing frameworks and reusable libraries, rather than any application code.

[Arjan van Wieringen]

I mean the performance implications. When are you entering a situation when this really starts to matter? And how much of a difference is it?

[CLOVIS]

I mean the performance implications.

Which implications are you thinking of?

Typealiases are purely syntactic sugar, they do nothing, so they do not have any performance difference compared to using what they refer to directly.

[Arjan van Wieringen]

I know, but I am asking OP. He specifically asked which one was better for performance and I am wondering what kind of ultra performant requirements there are that something like this would make sense