7. (10 points) Consider the following defined OO design constructs.

1. Specification

an abstract base class defines type utility by specifying a unifying public interface

to be instantiable, a descendant class must fully specify behavior to complete the type definition

2. Program to Interface Not Implementation (PINI)

Recall that type checking for dynamic binding may be done by the client (with or without help from the class designer) OR by the compiler

1. Under what assumptions do specification and PINI complement each other? Explain
2. Identify when a specification design could negatively impact type checking
3. How does client type checking undermines PINI? Explain