Abstraction (Cross Ref > Language Basics)

General Info: Abstract Class / Abstract Member

An abstract class member is a member that is specified in a class but not implemented. Classes that inherit from the class will have to implement the abstract member. Abstract members are a technique for ensuring a common interface with descendant classes. An abstract class is a class you cannot instantiate. A pure abstract class is a class with only abstract members.

Languages Focus

Abstraction is supported at various levels with each language. A language could enforce abstraction at the class level (either enforcing a no-instantiation rule or a only abstract members rule), and with class members (member methods and/or properties).

C#:   abstract, override C# supports abstract class members and abstract classes using the abstract modifier. An abstract class is a class with one or more abstract members and you cannot instantiate an abstract class. However, you can have additional implemented methods and properties. An abstract member is either a method (implicitly virtual), property, indexer, or event in an abstract class. You can add abstract members ONLY to abstract classes using the abstract keyword. Then you override it in a descendant class with Override. Syntax Example: abstract public class Cyborg : System.Object { abstract public void Speak(string pMessage); } public class Series600 : Cyborg { public override void Speak(string pMessage) { MessageBox.Show(pMessage); } }  C# Abstraction (abstract, override)

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