Re: ref object or object with ref field

[Krux02]

@Lando here an example for dynamic dispatch on value types.
    
    
    type
      A = object of RootObj
        a: string
      
      B = object of RootObj
        a:int
    
    method foo(arg: RootObj): void =
      discard
    
    method foo(arg: A): void =
      echo "A ", arg.a
    
    method foo(arg: B): void =
      echo "B ", arg.a
    
    var a = A(a: "abc")
    var b = B(a: 12345)
    
    var pointers : array[2, ptr RootObj] = [a.addr, b.addr]
    
    for p in pointers:
      p[].foo
    
    var references : array[2, ref RootObj]= [new(A), new(B)]
    
    for p in references:
      p[].foo