Well the method of the receiver can check for the type of the object from which you receive a message, technically you can restrict the access even to a particular instance object. You can enforce a ton of restrictions as the entire system is modifiable and live.��

On Wed, Oct 18, 2017 at 8:37 AM Prof. Andrew P. Black <black@cs.pdx.edu> wrote:

On 18 Oct 2017, at 08:32 , James Ladd <ladd.james@gmail.com> wrote:

What if accessors were generated but not mutators?

The point is that, once a method exists, there is not way to restrict who can send a message that will execute it.�� So if one were forces to generate a reader method, or a writer method, just to give access to a subclass, then every object n the system would also gain access.

Andrew