Why does `Array` have an inline constructor; when ...

# announcements

[darkmoon_uk]

Why does Array have an inline constructor; when the compiler says this is disallowed in my own code?

[voddan]

darkmoon_uk: what constructor are you referring to?

[voddan]

(AFAIK inline constructor is not a thing)

[darkmoon_uk]

Exactly my point...

[darkmoon_uk]

but look at kotlin.Array

[darkmoon_uk]

public inline constructor(size: Int, init: (Int) -> T)

[voddan]

👀

[darkmoon_uk]

And something about it is really ruining my day; something I thought would be easy... I want to create an Array<T> inside MyClass<T>'s initializer. It won't have it, because calling Array<T> it's insisting it be reified, and I can't have reified T inside a constructor!

[darkmoon_uk]

I can pass in KClass, but that doesn't help with creating Array<T> either.

[darkmoon_uk]

I can make a reified create() method in Companion class, but that requires I expose the Array<T> as part of MyClass's public constructor, which I don't want to do.

[darkmoon_uk]

It looks like a bit of a hole in the language TBH

[voddan]

Arrays ARE objects, bth. inline there is for the lambda performance

[darkmoon_uk]

Hmm, I guess this is no more restrictive than Java, will have to consider using Array<Any?> and casting inside my class.

[darkmoon_uk]

Thx.

[voddan]

@darkmoon_uk I know I've mentioned it, but why would you use Array instead of List or MutableList? Their performance are exactly the same, but lists have normal generics

[darkmoon_uk]

...with it's immediate, fixed size specification and initialization function, this is the exact API I would like to store image data.

[darkmoon_uk]

I can recreate this for list but it will be extra work, it's a shame the generic behaviour of Array is peculiar. Especially when it's all just same-sized object pointers at the end of the day.

[voddan]

initialization function

Do you mean that? https://github.com/JetBrains/kotlin/blob/1.1.2/libraries/stdlib/src/kotlin/collections/Collections.kt#L123

[darkmoon_uk]

Shame, gratitude... thanks.

[darkmoon_uk]

List fixes all 🙂

[voddan]

Shame on us as a community, because those function are really tough to find without knowing they exist. We need new ideas for docs, and fast

[radityagumay]

Actually inline for performance purpose and you can inline kind of tailrecursion for example

[radityagumay]

Kindly watch hadi hariri presentation about tailrecursion