Object Oriented Programming using C#

Object Oriented Programming using C#
Object Roles and the Importance of Polymorphism

We can show CashTill on a class diagram as below :-

Note that CashTill has a dependency on Publication because the SellItem() method is passed a parameter of type
Publication. What is actually passed will of course be an object of one of the concrete types descended from
Publication.

Activity 2

Look at the diagram below and, assuming Publication is not an abstract type, decide which of the pairs of operations

shown are legal.