From K/N CInterop guide on kotlin webpage: ```We use the staticCFunction{..} helper function from Ko...

# kotlin-native

[Big Chungus]

From K/N CInterop guide on kotlin webpage:

We use the staticCFunction{..} helper function from Kotlin/Native to wrap a Kotlin lambda function into a C function pointer. It only allows having unbound and non-capturing lambda functions.

Could someone elaborate on what it means by unbound and non-capturing lambda functions. Does it mean that for instance if you want to register callbacks from c they cannot be in a kotlin class, but rather only top-level function?

[Kris Wong]

i'm not clear on unbound, but non-capturing means that it does not contain references to the context in which it is used

[Big Chungus]

So does that mean there's no way to wrap GTK3 C callbacks in classes for reusability? Even something as a pair of click count buttons managed by Wrapper class?

[Big Chungus]

@msink found this snippet in your libui

/** Function to be run when the user makes a change to the TextField.
     *  Only one function can be registered at a time. */
    fun action(block: TextField.() -> Unit) {
        action = block
        uiEntryOnChanged(ptr, staticCFunction { _, ref ->
            with(<http://ref.to|ref.to><TextField>()) {
                action?.invoke(this)
            }
        }, ref.asCPointer())
    }

    internal var action: (TextField.() -> Unit)? = null

Can you explain why the compiler does not complain that action is outside the function?

[Kris Wong]

they can exist within a class but can't capture any reference to the class

[Big Chungus]

Also how can I obtain the referenced value from COpaquePointer as:

<http://ref.to|ref.to><TextField>()

[Big Chungus]

Nvm, figured it out:

ref.asStableRef<TextField>().get()