OOPS concenpts in .Net, inheritance, Abstraction and Polymorphism
Inheritance
In the real world there are many objects that can be specialized. In OOP, a parent class can inherit its behavior and state to children classes. This concept was developed to manage generalization and specialization in OOP and is represented by a is-a relationship.
The following OO terms are commonly used names given to parent and child classes in OOP:
· Superclass: Parent class.
· Subclass: Child class.
· Base class: Parent class.
· Derived class: Child class
The most common real world sample to explain inheritance is the geometric shapes object model. Squares, circles, triangles, rectangles, pentagons, hexagons, and octagons are geometric shapes. The following figure shows a sample set of geometric figures:
The concept of generalization in OOP means that an object encapsulates common state an behavior for a category of objects. The general object in this sample is the geometric shape. Most geometric shapes have area, perimeter, and color. The concept of specialization in OOP means that an object can inherit the common state and behavior of a generic object; however, each object needs to define its own special and particular state an behavior
Multiple inheritance
Multiple inheritance is the possibility that a child class can have multiple parents. Human beings have always two parents, so a child will have characteristics from both parents.
In OOP, multiple inheritance might become difficult to handle because it allows ambiguity for the compiler. There are programming languages such as C++ that allow multiple inheritance; however, other programming languages such as Java and the .NET Framework languages do not allow multiple inheritance. Multiple inheritance can be emulated in .NET using Multiple Interface Inheritance, which I will explain in Part 3 of this series.
Sealed class
A sealed class is a class that does not allow inheritance. Some object model designs need to allow the creation of new instances but not inheritance, if this is the case, the class should be declared as sealed.
Abstraction
Abstraction is “the process of identifying common patterns that have systematic variations; an abstraction represents the common pattern and provides a means for specifying which variation to use" (Richard Gabriel).
For more details and examples, please look at the link given below:
Reference: http://zonixsoft.wordpress.com/2008/06/14/oops-concepts-and-net-part-2-inheritance-abstraction-polymorphism/