General propositions do not decide concrete cases.
—Oliver Wendell Holmes
A philosopher of imposing stature doesn’t think in a vacuum. Even his most abstract ideas are, to some extent, conditioned by what is or is not known in the time when he lives.
—Alfred North Whitehead
In this chapter you’ll learn:
• How polymorphism enables you to “program in the general” and make systems extensible.
• To use overridden methods to effect polymorphism.
• To create abstract classes and methods.
• To determine an object’s type at execution time.
• To create
sealed methods and classes.
• To declare and implement interfaces.
• To overload operators to enable them to manipulate objects.