Blocking Inheritance
Allowing inheritance yields a great amount of flexibility with regard to API design. At the same time, it comes as a big responsibility for the designers of the base classes. If the behavior of a base class method changes, it might break subtypes. This is especially true if virtual methods are used, as you will see later.
To avoid such responsibilities, you can mark a class as noninheritable by means of the sealed
keyword. Doing so prevents anyone from inheriting from the class:
sealed class Student : Person{ ...}class GraduateStudent : Student // fails to compile{}
Figure 14.8 shows the error emitted by the compiler in this case. Later you see how you can apply the sealed
keyword to a member. ...
Get C# 5.0 Unleashed now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.