anyone who would be able to help ? I think I have lost type safety using inline function with reifie...

# getting-started

[Jiri Bruchanov]

anyone who would be able to help ?
I think I have lost type safety using inline function with reified type, but not sure why

[Jiri Bruchanov]

having following code

import kotlin.reflect.KClass

interface NavArgs
interface LifecycleComponent
interface NavToken<T : NavArgs>

class NavRecord<T : NavArgs, LC : LifecycleComponent>(
    val navToken: NavToken<T>,
    val klass: KClass<out LC>,
    val content: (LC) -> Unit
) {
    fun execute(lc: LC) {
        content(lc)
    }
}

inline fun <reified LC : LifecycleComponent, T : NavArgs> screen(
    navToken: NavToken<T>,
    noinline content: (LC) -> Unit
): NavRecord<T, LC> = NavRecord(navToken, LC::class, content)

class MyLifecycleComponent/* : LifecycleComponent */
object Stats : NavToken<NavArgs>

fun main() {
    val record = screen(Stats) { component: MyLifecycleComponent ->
        //why is this working ^^
    }
    
    //this is correctly failing because of types
    NavRecord(Stats, MyLifecycleComponent::class, { lc: MyLifecycleComponent -> })
    record.execute(MyLifecycleComponent())
}

[Jiri Bruchanov]

but not sure why the screen(...) isn't compiler error

[Landry Norris]

The type of Stats is NavToken<NavArgs>. Screen wants a NavToken<T>, where T is a subclass of NavArgs. This is valid.

[Jiri Bruchanov]

That's imo unrelated

class MyLifecycleComponent : LifecycleComponent

having ^ type as expected just compiles fine

[Jiri Bruchanov]

but for some reason, using

val record = screen(Stats) { component: MyLifecycleComponent ->
        //why is this working ^^
}

just doesn't care if MyLifecycleComponent is NOT LifecycleComponent

[Landry Norris]

Same thing with the function taking in a subclass of LifecycleComponent. It says it needs LC where LC is a subclass of LifecycleCompenent. MyLifecycleComponent is a valid subclass of LifecycleComponent.

[Landry Norris]

I see that it’s commented out now.

[Jiri Bruchanov]

I'd like to see also

val record = screen(Stats) { component: MyLifecycleComponent -> }

^ to be a compiler issue as MyLifecycleComponent is NOT LifecycleComponent

[Jiri Bruchanov]

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