Untitled

type
    Base = ref object of RootObj
    A = ref object of Base
    B = ref object of Base

proc inner(obj: Base) =
    echo "to override"

proc outer[T](obj: T) =
    mixin inner
    echo "outer"
    obj.inner()

proc inner(obj: A) =
    echo "inner A"

proc inner(obj: B) =
    echo "inner B"

var a: A
var b: B

a.outer()
b.outer()