Design Patterns in C# With Real-Time Examples

In this article series, I am going to discuss the Design Patterns in C# with real-time examples using different types of dot net applications which include ASP.NET MVC, Web API, and Console Applications. It is very easy to understand and implement design patterns with real-time applications. Writing the code with design patterns will make your applications more Reliable, Scalable, and Maintainable.

For Whom?
These tutorials are design for beginners as well as professionals developers who want to learn Dot Net Design Patterns with Real-time Examples step by step from the very basics to the advanced concepts of many different types of Design Patterns in C# with real-time examples. This C# Design Patterns tutorial seriously provides a hands-on approach to the subject with step-by-step programming examples that will assist you to learn and put the acquired knowledge into practice.

History and Evolution of Design Patterns
The four authors of the book famously know as Gang of four is the ones who brought the concepts of design patterns in their book “Elements of Reusable Object-Oriented Software”.

Gang of Four has divided the book into two parts with the first part explaining the pros and cons of object-oriented programming and the second part describes the evolution of 23 classic software design patterns.

What are Design Patterns?
Design Patterns are nothing but documented and tested solutions for recurring problems in a given context. So, in simple words, we can say that the Design Patterns are reusable solutions to the problems that as a developer we encounter in our day to day programming. Design Patterns are basically used to solve the problems of object generation and integration.

The Design Pattern is not a silver bullet. Let us understand what it means. While developing your project you know your project requirement better. We have many design patterns. Take the design pattern as a reference and see does the design pattern does really solve your project problem. If yes, then only use the design pattern.

Do not overdo design patterns. One thing you need to remember is that the design patterns are for projects and projects are not for patterns. I saw many developers are enforcing the design pattern into their project which makes the project messy. So, use only when it required.

Types of Design Patterns
Gang of Four categorized the Design Pattern into three main categories based on the three problem area of software architecture. They are as follows.

1. Creational Design Pattern
2. Structural Design Pattern
3. Behavioral Design Pattern

Creational Design Patterns:
If you have a huge project with a lot of classes, a lot of classes mean you are going to deal with a lot of objects. So you need to create different objects (like new Customer(), new product(), new invoice(), etc.). If these objects creations are scattered on the client code, then it leads to lots of complicated logic at the client code. If the object creations are not centralized then it leads to very complicated code. The Creational Design pattern centralized the object creation logic.

As the name says these design patterns deal with object creation and initialization. Creational design pattern gives the programmer more flexibility in deciding which objects need to be created for a given case. Examples of Creational design patterns category: Singleton, Factory, Builder, Prototype, Fluent Interface, Factory Method, and Abstract Factory.

Structural Design Patterns:
Sometimes you need to change the structure of a class or you can say the relationship between the classes but you don’t want the project to be affected. For example, if you have a customer and product class and the product class is used inside the customer class making one to many relationships. Tomorrow, as the project proceeds, the customer wants to keep away the product class as they want to use the product and customer class independently. This is a structural change and you don’t want this structural change to affect your project. This is where the Structural Design Pattern helps us.

In simple words, this pattern focuses on the decoupling interface, implementation of classes and its objects. Examples of Structural design patterns category: Adapter, Facade, Decorator, Composite, Proxy, Flyweight, and Bridge Design Pattern.

Behavioral Design Patterns:
Sometimes you want to change the behavior of a class and again you want it to affect other classes of the project. For example, you have an Invoice class which currently applying taxes as 18%. Tomorrow if you have to add another extra tax. That means you are changing the behavior of a class. To solve such type of Behavioral issues Behavioral Design Pattern comes into the picture.

These patterns deal with communication between Classes and objects. Examples of Behavioral design patterns: Chain of Responsibility, Command, Observer, Iterator, State, Template Method, Visitor, Strategy, Mediator, Memento, and Interpreter Design Pattern.

How easily you are going to understand the design patterns that basically depends on how strong you are in object-oriented programming concepts. So, to take the full advantages of this Design Patterns in C# tutorials, it is very important for you to have at least the basic knowledge of the following object-oriented programming concepts.

1. Abstraction
2. Inheritance
3. Polymorphism
4. Encapsulation
5. Interfaces
6. Classes
7. Abstract classes

Along with GoF 23 Design Patterns, we are also going to discuss the following dot net design patterns which are used frequently in most of the real-time applications.
Dependency Injection Design Pattern.
Dependency Injection using Unity Container.
Repository Design Pattern using C#.
Repository Design Pattern using Unity of Work.
Inversion of Control in C#.

If you have any doubts or if you want to learn any design pattern which we missed in this course, then please give us a comment and we promised we will provide as soon as possible.