C# 2010 All-in-One For Dummies®

Chapter 7. Poly-what-ism?

In This Chapter

• Deciding whether to hide or override a base class method (so many choices!)

• Building abstract classes — are you for real?

• Declaring a method and the class that contains it to be abstract

• Using ToString, the class business card

• Sealing a class from being subclassed

In inheritance, one class "adopts" the members of another. Thus I can create a class SavingsAccount that inherits data members such as account id and methods such as Deposit() from a base class BankAccount. That's useful, but this definition of inheritance isn't sufficient to mimic what's going on out there in the business world.

Tip

See Chapter 6 of this minibook if you don't know (or remember) much about class inheritance.

A microwave oven is a type of oven, not because it looks like an oven but, rather, because it performs the same functions as an oven. A microwave oven may perform additional functions, but it performs, at the least, the base oven functions — most importantly, heating up my nachos when I say, "StartCooking." (I rely on my object of class Refrigerator to cool the beer.) I don't particularly care what the oven must do internally to make that happen, any more than I care what type of oven it is, who made it, or whether it was on sale when my wife bought it. (Hey, wait — I do care about that last one.)

From our human vantage point, the relationship between a microwave oven and a conventional oven doesn't seem like such a big deal, but consider the problem from the oven's ...