Beginning ASP.NET 4.5 in CSharp and VB Opsylum

Object Orientation Basics x 197
C#
Person myPerson = new Person() { FirstName = "Imar", LastName = "Spaanjaars" };
In VB.NET, you need the With keyword in front of the properties list. In addition, you need to prefix
each property name with a dot (.). Other than that, the syntax is the same for both languages.
Object initializers are great if you need to set a bunch of properties on an object quickly without
being forced to write specialized versions of the constructors.
Although it’s useful to have this Person class in your application, at times you may need specialized
versions of a Person. For example, your application may require classes like Employee and Student.
What should you do in this case? Create two copies of the Person class and name them Employee
and Student, respectively?
Although this approach certainly works, it has a few large drawbacks. The biggest problem is the
duplication of code. If you decide to add a SocialSecurityNumber property, you now need to add it
in multiple locations: in the general Person class and in the Employee and Student classes. Object
inheritance, a major pillar of object orientation, is designed to solve problems of this kind.
Inheritance
Earlier you learned that System.Object is the parent of all other data types in .NET, including
all the built-in types and types that you define yourself, meaning that each type in .NET (except
Object itself) inherits from Object. One of the benefits of inheritance is that you can define a
behavior at a high level (for example in the Object class) that is available to inheriting classes automatically
without the need to duplicate that code. In the .NET Framework, the Object class defines
a few members that all other objects inherit, including the ToString() method.
To let one class inherit another, you need to use the Inherits keyword in
VB.NET and the colon (:) in C#, as shown in the following example that
defines a Student class that inherits Person:
VB.NET
Public Class Student
Inherits Person
C#
public class Student : Person
{
}
To see how inheritance works, think again about the Person class shown in
earlier examples. That class had a few properties, such as FirstName and
LastName, and a Save method. But if it is inheriting from Object, does it
also have a ToString() method? You bet it does. Figure 5-7 shows the relationship
between the Object class and the Person class that inherits from
Object.
FIGURE 5-7