enum NAME, METHOD

procedure me_t()
    puts(1,"I is a T\n")
end procedure
constant r_t = routine_id("me_t")

procedure me_s()
    puts(1,"I is an S\n")
end procedure
constant r_s = routine_id("me_s")

type T(object o)
    -- as o[METHOD] can be overidden, don't verify it!
    return sequence(o) and length(o)=2 and string(o[NAME]) and integer(o[METHOD])
end type

type S(T t)
    return t[METHOD] = r_s
end type

S this = {"S",r_s}
T that = {"T",r_t}

call_proc(that[METHOD],{})
that = this
call_proc(that[METHOD],{})