Two MapBuilder

MapBuilder1.kt

inline fun <reified T, reified U> mapBuilder() = MapBuilder(T::class.java, U::class.java)

class MapBuilder<T, U>(
        private val tClass: Class<T>,
        private val uClass: Class<U>
) {
    operator fun invoke(arg: Any): MapBuilder<T, U> {
        when {
            tClass.isAssignableFrom(arg.javaClass) -> {
                // you got a T
            }
            uClass.isAssignableFrom(arg.javaClass) -> {
                // you got a U
            }
            else -> // you got an invalid argument
                throw IllegalArgumentException("Arg ${arg.javaClass} is not a $tClass or $uClass")
        }
        return this
    }
}


fun usage(){
    mapBuilder<String, Int>()("Hello")(1234)("World!")
}

class MapBuilder<T:Any, U: Any> {
    /**
     * for create map in syntax like
     * val mb = MapBuilder<String, Double>()("axis_x")(8.0)("axis_y")(7.0).get()
     * instead
     * val mc = mapOf("hello" to 10.0, "world" to 5.0)
     * don't have to used with same types
     * @param T should be different of U.
     * @param U should be different of T.
     **/
    private lateinit var map: MutableMap<T, U>
    private lateinit var key: T

    @JvmName("invoke withT")
    operator fun invoke(first: T): MapBuilder<T, U> {
        key = first
        return this
    }

    @JvmName("invoke withU")
    operator fun invoke(double: U): MapBuilder<T, U> {
        map[key] = double
        return this
    }

    fun get(): Map<T, U> {
        return map
    }
}