问题
I know (from the compiler's errors) that a constant property cannot be overridden by a constant, nor can it be overridden by the getter of a computed property. Obviously they can't be overridden by anything non-constant. There's no reason to add observers to them, either, since they'll never change. And yet final let seems to be a thing.
Is it impossible to override a stored constant property? Is final let exactly equivalent to let?
来源：https://stackoverflow.com/questions/35671819/is-it-impossible-to-override-a-constant-stored-property