The word “polymorphism” means “different forms”. Applied in object-oriented paradigm it means the ability of an entity to exhibit different forms at runtime. However, why would such a kind of feature be required? One major reason to have this is to eliminate the type inspection. As we can see in the earlier case study that we discussed there would also be a type inspection checking at the client application level where in the employee entities would be used. So just as in every functionality, we had checked for the type of employee we will also have to check in the main function about the type of employee we are handling. With polymorphism, we can have this level of type inspection also being eradicated totally.
Mapping the procedural approach to an object oriented scenario
How does .NET support object oriented programming?
As we have discussed in the earlier sections .NET happens a to be a “complete framework”. The basic approach adopted by the framework is object-oriented and the framework would support only object-oriented code. So no more C and COBOL applications! Although C++ and OO-COBOL would work perfectly fine.
Since the framework is inherently object-oriented everything i.e. every data type in the framework will be a class. Unlike C++, even the primitive data types will be given by the framework as a set of classes.
The framework also provides us with a rich set of classes which can be used by instantiating them or writing new classes by deriving from the framework classes. The framework does have a systematic organization of classes wherein the Object class from the System namespace (we will discuss namespaces in details later) tops the chart. All the other classes are derived from the Object class.
Component Oriented Programming
However, is it really enough just to have an object oriented approach? Well, now with the increasing influence of the web and code reusability getting extended across the language barriers its very much essential to even extend “Object Oriented approach “ itself.
We need to extend the definition of the “class” which happens to be the basic element of object oriented programming. We know that the class serves as an abstraction or simulation of a real life entity. However, in order to have a total encapsulation the internals of the class has to be totally hidden. Secondly, the class should be instantiable across various programming languages to have a more range of reusability. The class should ideally support properties (will be discussed a little later) to offer more user friendliness and overcoming the incompatibilities.
Therefore, a class must have the following extra abilities in addition to what it serves in object-oriented scenario:
• Encapsulated data and implementations
• Properties
• Language Interoperable
We can term instance of such a class as a “component”. VB.NET and CSharp happen to be component- oriented languages in a way that every class created in any of these languages when instantiated results in a component.