How to call arbitrary method as Any type with argument list of Any*?

Question

How would I implement the following method in Scala, given that method is a function that can take the amount of arguments in arguments ?

def applyAny(method: Any, arguments: Any*) = ???

My intended use for this is in combination with scala.Dynamic , like so:

val dynamicValue: Dynamic
dynamicValue.myAdd = (x,y) = > x + y
dynamicValue.myAdd(2,3)

Answer 1

I take it from your example snippet that you intend these "methods" to be one of the 23 FunctionN types.

In that case, there is not much you can do but to use runtime dispatch on said 23 types:

def applyAny(method: Any, arguments: Any*): Any = (arguments.size, method) match {
  case (0, f: Function0[_]) =>
    f()
  case (1, f: Function1[_, _]) =>
    f.asInstanceOf[Function1[Any, Any]](arguments(0))
  case (2, f: Function2[_, _, _]) =>
    f.asInstanceOf[Function2[Any, Any, Any]](arguments(0), arguments(1))
  ...
  case (22, f: Function22[_, _, ..., _]) =>
    f.asInstanceOf[Function22[Any, Any, ..., Any]](arguments(0), arguments(1), ..., arguments(21))
  case _ =>
    sys.error("Arity mismatch")
}

Not pretty, and lots of opportunities for ClassCastException s at runtime in various places.