type Base = ref object of RootObj A = ref object of Base B = ref object of Base method inner(obj: Base) {.base.} = quit "to override" method outer(obj: Base) {.base.} = echo "outer" obj.inner() method inner(a: A) = echo "inner A" method inner(b: B) = echo "inner B" var a: A var b: B a.outer() b.outer()