Design Patterns in C# With Real-Time Examples

Design Patterns in C# With Real-time Examples

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

For Whom?

These tutorials are designed for Students, Beginners as well as Professional Developers who want to learn and enhance their knowledge of Design Patterns with Real-time Examples using .NET Applications. Here, we will explain all the design patterns step by step i.e. first we will discuss the definition, then we will give a simple as well as multiple real-time examples, then we will discuss how to implement the same using .NET Application, then we will compare the example with the UML diagram of the design pattern so that you will understand the concept very easily. This Design Patterns in C# with Examples tutorial series 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 known as the Gang of four are the ones who brought the concepts of design patterns in their book “Elements of Reusable Object-Oriented Software”. Gang of Four (GoF) has divided the book into two parts with the first part explaining the Pros and Cons of Object-Oriented Programming and the second part describing the Evolution Of 23 Classic Software Design Patterns.

What are Design Patterns?

Design Patterns are nothing but, you can say, documented and tested solutions for recurring problems in a given context. So, in simple words, we can say that 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. As we progress in this Design Patterns series, you will understand what are Object Generation and Integration problems and how we solve them using different design patterns.

Design Pattern is not a Silver Bullet. What it means. While developing your project, you know your project requirements better. And we have many design patterns. Take the design pattern as a reference and see does the design pattern really solves your project problem. If yes, then only use the design pattern.

Do not Overdo Design Patterns. What it means. One thing you need to remember is that the design patterns are for projects and projects are not for patterns. I saw many developers enforcing the design pattern in their projects even though the design pattern is not required which makes the project messy. So, use Design Patterns only when required.

Note: Sometimes for a given context, we may need to use more than one design pattern to solve the problem. Every design pattern has pros and cons, so only use the design pattern when you are getting more pros than cons.

Types of Design Patterns

Gang of Four (GoF) categorized the Design Pattern into three main categories based on the three problem areas (Object Creation and Initialization, Structural Changes of Classes, and Interfaces, and the Relationship Between Classes, Communication Between Objects) of software architecture. They are as follows.

1. Creational Design Pattern (Object Creation and Initialization)
2. Structural Design Pattern (Structural Changes of Classes, and Interfaces, and the Relationship Between Classes)
3. Behavioral Design Pattern (Communication Between Objects)

Creational Design Patterns:

The Creational Design Pattern deals with Object Creation and Initialization. The Creational Design Pattern gives the programmer more flexibility in deciding which objects need to be created for a given case. For example, if we have a huge project, a huge project means we have a lot of classes, and a lot of classes mean we are dealing with a lot of objects. So we need to create different objects (like new Customer(), new Product(), new Invoice(), etc.) based on some conditions.

If the object creation logic based on some condition is implemented in the client code, then it leads to a lot of complicated logic in the client code. Client code means the class that is going to consume the object. That means if the object creations and initialization logic are not centralized, then it leads to a very complicated client code.

The Creational Design Pattern helps us to centralize the object creation and initialization logic and depending upon the condition, it will create and initialize the appropriate object and returns that object to the client and then the client can consume the object by calling the necessary methods and properties. The client does not know how the object is created and initialized. If this is not clear at the moment, then don’t worry, we will discuss Creational Design Patterns in detail in our upcoming articles.

Examples of Creational Design Patterns are Singleton, Factory, Builder, Prototype, Fluent Interface, Factory Method, and Abstract Factory.

Structural Design Patterns: 

The Structural Design Pattern is basically used to Manage the Structure of Classes and Interfaces as well as Manage the Relationship Between the Classes and Interfaces. For example, if we 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, now we want to keep away the product class from the Customer class as we want to use the Product and Customer classes independently. This is a structural change and we don’t want this structural change to affect our project. This is where the Structural Design Pattern helps us. If this is not clear at the moment, don’t worry, we will discuss Structural Design Patterns in detail in our upcoming articles.

Examples of Structural Design Patterns are Adapter, Facade, Decorator, Composite, Proxy, Flyweight, and Bridge Design Patterns. 

Behavioral Design Patterns: 

Behavioral Design Patterns deal with the Communication Between Classes and Objects. That means if you want to change the behavior of a class again you want it to affect other classes of the project as well. For example, you have an Invoice class that currently applies 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 types of Behavioral issues Behavioral Design Pattern comes into the picture.

Examples of Behavioral Design Patterns are Chain of Responsibility, Command,  Observer, Iterator, State, Template Method, Visitor, Strategy, Mediator, Memento, and Interpreter Design Pattern.

Pre-Requisites to Learn Dot Net Design Patterns:

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 full advantage of these Design Patterns using C#, 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