Does anyone know why `kotlin.Number` is an abstrac...

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[ross_a]

Does anyone know why kotlin.Number is an abstract class, rather than an interface?

[Tsvetozar Bonev]

Becuase it holds a value I reckon, would be kind of awkward to have an intreface backing data types.

[elizarov]

No. It is purely abstract. Mostly, it is just a Java legacy in its design. But it is somewhat logical in the sense that being a number is pretty exclusive property. It is hard to imagine something being some other kind of entity and also serve its double-duty as a number.

[elizarov]

(everything else about its design is quite illogical, though)

[ross_a]

Yeah..

[ross_a]

I'm looking at possibly porting this to use inline classes, but obviously inline classes can only implement interfaces, not extend abstract classes

[ross_a]

https://github.com/tools4j/decimal4j

[ross_a]

at a first glance I think you can get the performance characteristics of what's called the "native decimal" in the benchmarks, but with the nicer API of the Immutable/MutableDecimal classes

[ross_a]

It was just a curiosity I came across though, it doesn't have to extend Number, I just thought it was a bit strange. Thanks for the confirmation 🙂

[karelpeeters]

Just don't extend it, the Number class is almost completely useless anyway.