Hi, anyone knows how I can make the following snippet more safe?

/** Matches [android.support.v7.app.AppCompatViewInflater.createView] content. */
val appCompatViewFactory = { clazz: Class<out View>, context: Context, _: Style<out View>? ->
    when (clazz) {
        TextView::class.java -> AppCompatTextView(context)
        Button::class.java -> AppCompatButton(context)
        ImageView::class.java -> AppCompatImageView(context)
        EditText::class.java -> AppCompatEditText(context)
        ...
        else -> null
    }
}

The issue is that there's no type check, I could return anything for anytype and the compiler won't fail. I want to make sure each when branch returns an object of the type of the case on which it matched.

there is no way to do that in kotlin

I think I'll submit an issue. This could definitely be supported in some way

how would that work?

Allowing reification of

Class<*>

and smartcasting checks on its instances (like

TextView::class.java

in my example). This would require me to make my function generic to benefit from this.

would something like this help?

inline fun <reified T : View> factory(clazz: Class<T>, context: Context) = when (clazz) {
    TextView::class.java -> AppCompatTextView(context)
    Button::class.java -> AppCompatButton(context)
    ImageView::class.java -> AppCompatImageView(context)
    EditText::class.java -> AppCompatEditText(context)
    else -> throw RuntimeException()
} as T

@arekolek Nope because there is no smart cast, which means you can return

Any?

where a

TextView

or other specific type was expected

wouldn’t that fail at the

as T

point?

Yes, but it happens at runtime, not compile time, and I already check the type was what was requested in the caller code

is

TextView

the same class that

AppCompatTextView

returns?

AppCompatTextView

is a

TextView

ah ok

By getting the type from the class parameter

but at runtime the generic type is removed

It's passed as a parameter (

Class<V>

)