Problem Statement

Multiple inheritance allows to specify that one class is a subclass of several other classes. Some languages allow multiple inheritance for arbitrary classes,   others restrict it to interfaces,   some don't allow it at all.

Write two classes (or interfaces) Camera and MobilePhone,   then write a class CameraPhone which is both a Camera and a MobilePhone. There is no need to implement any functions for those classes.

Let's start with the solution:

type
  Camera = ref object of RootObj
  MobilePhone = ref object of RootObj
  CameraPhone = object
    camera: Camera
    phone: MobilePhone
proc `is`(cp: CameraPhone, t: typedesc): bool =
  for field in cp.fields():
    if field of t:
      return true
var cp: CameraPhone
echo(cp is Camera)
echo(cp is MobilePhone)