I feel dumb - what is best way to get C string allocated in nativeHeap from Kotlin String?

# kotlin-native

[msink]

I feel dumb - what is best way to get C string allocated in nativeHeap from Kotlin String?

[msink]

/** Provides a complete description of a font where one is needed.  */
open class Font(
    family: String? = null,
    size: Double = 0.0,
    weight: uiTextWeight = uiTextWeightNormal,
    italic: uiTextItalic = uiTextItalicNormal,
    stretch: uiTextStretch = uiTextStretchNormal
) : Disposable<uiFontDescriptor>(
    alloc = nativeHeap.alloc<uiFontDescriptor>().ptr
) {
    init {
        with(ptr.pointed) {
            Family = family?.cstr.rawPtr //.getPointer(nativeHeap)
            Size = size
            Weight = weight
            Italic = italic
            Stretch = stretch
        }
    }

    override fun clear() {
        ptr.pointed.Family?.let { nativeHeap.free(it) }
    }

    override fun free() {
        clear()
        nativeHeap.free(ptr)
    }
}

[msink]

Family is C string = so how to initialize it in Kotlin wrapper?

[JoakimForslund]

Have you looked into ArenaBase?

[msink]

Recomended in INTEROP.md way does not work:
val cString = kotlinString.cstr.getPointer(nativeHeap)
Error: type mismatch Required: AutofreeScope Found: nativeHeap

[olonho]

somewhat imperfect but this shall work fun mycstring(s: String) = s.cstr.place(nativeHeap.allocArray(s.length * 4))

[svyatoslav.scherbina]

I find using Arena the most idiomatic approach for this case.
You can create one along with object instance and dispose in clear.
See also https://github.com/JetBrains/kotlin-native/blob/master/samples/videoplayer/src/videoPlayerMain/kotlin/Disposable.kt

The arena object can be used in getPointer.