type
Component {.inheritable.} = ref object
A = ref object of Component
x: int
B = ref object of Component
y: int
var components: seq[Component]
components.add A(x: 1)
components.add B(y: 2)
echo components[0] of A # true
echo components[1] of B # true
echo components[0].A.x # 1
echo components[1].B.y # 2
Run.
