Design Patterns in .Net

Hi Friends,

This article is related to the Design Patterns in C#. Here I will explain about what is Design pattern, Why we need Design patterns, Where we can use the design Patterns, what are the various Classifications of Design Patterns according to GoF(Gang Of Four) Organization, What are the situation where the Design Patterns can be useful and finally do we really need to Design Patterns for our application and then the explanation of each design pattern with examples.

So first let’s talk about ‘What is the Design Pattern?’:

Design Pattern is the way to solve the recurring problems which occur during the designing of the software applications.

Q. Why we need design patterns?

A. Design patterns are needed to make the solution more decouples i.e. components should not be dependent to each other. This will make the solution more maintainable as well as scalable in the future prospect. In the future, if the application needs some additional component’s to be added; it will need few changes rather than changing in the whole application. So to do this, our solution should be more decoupled. Hence the Design pattern is the way to make the application more decoupled.

Q. Where we can use Design Patterns:

A. Design patterns are used in the solutions, where there is the need to scale the application in the future and to make the application more maintainable. If there is no scope of maintenance and scalability in the solution, Design Pattern is not the preferred way to implement as it will slow down the performance of the overall application.

Q. Classifications of Design Patterns according to GoF:

A. According to the GoF (Gang of Four) company, the design patterns can be classified in to 3 groups:

1. Creational Design Patterns

2. Structural Design Patterns

3. Behavioral Design Patterns

Creational Design Patterns: When the design pattern is used in the creating of the new object, creational design patterns are used. There are few design patterns which comes under this category-

·         Factory & Abstract Factory Design Pattern
·         Builder Pattern
·         Singleton Pattern
·         Prototype Pattern
·         Lazy Initialization Pattern

  

Structural Design Patterns: When the design pattern is applied in the structure of the object, structural design patterns are used. There are few design patterns which comes under this category-

·         Facade Pattern
·         Adapter Pattern

·         Bridge Pattern

·         Composite Pattern

·         Decorator Pattern

·         Flyweight Pattern

·         Proxy Pattern

           

Behavioral Design Patterns: When the design pattern is applied in the behavior of the object, behavioral design patterns are used. There are few design patterns which comes under this category-

·         Strategy Pattern

·         Observer Pattern or Publish-Subscribe Pattern

·         Chain of Responsibility Pattern

·         Command Pattern

·         Interpreter Pattern

·         Iterator Pattern  

·         Mediator Pattern

·         Memento Pattern

·         State Pattern 

·         Template Pattern

·         Visitor Pattern

Q. Situations where the Design patterns are useful:

A. When the application is large and scalable as well as it needs modifications in the coming future, Design Pattern is the best way to implement to make the solution more de-coupled so that individual components of the application should not be dependent to each other and the modification in one component should not affect the others.

Q. Do we really need to Design Patterns?

A. It’s always a good practice to use the Design patterns while developing the applications. Design Patterns will be more useful when the project scope could be increasing in future. But it is not mandatory to use design pattern when the scope of the project is limited and in the future the project will not be scalable.

Q. Explain about the Creational Design Patterns? Why they called as Creational Design Patterns?

A.

Q. Explain about the Structural Design Patterns? Why they called as Structural Design Patterns?

A.

Q. Explain about the Behavioral Design Patterns? Why they called as Behavioral Design Patterns?

A.