SOLID Design Principles in C#

 The SOLID Design Principles are the design principles that help us to solve most of the software design problems. These design principles provide us with multiple ways to move the tightly coupled code between the software components which makes the software designs more understandable, flexible, and maintainable. 

Why do we need SOLID Principles?

As a developer, we start developing applications using our experience and knowledge. But over time, the applications might arise bugs. We need to alter the application design for every change request or for a new feature request. After some time we might need to put a lot of effort, even for simple tasks and it might require the full working knowledge of the entire system

Advantages of SOLID Principles in C#

Maintainability: 

As we know, nowadays maintaining software is very important for organizations. Day by day the business may grow for the organization and you may need to enhance the software with new changes. So you need to design the software in such a way that it should accept future changes without any problem.

Testability:

Test-Driven Development (TDD) is one of the most important key aspects nowadays when you need to design and develop a large-scale application. We need to design the application in such a way that we should test each individual functionalities. 

Flexibility and Extensibility:

Nowadays flexibility and extensibility both are very much required for enterprise applications. So we should design the application in such a way that it should be flexible so that it can be adapted to work in different ways and extensible so that we can add new features easily with minimum modifications.

Parallel Development:

The Parallel Development of an application is one of the most important key aspects. As we know it is not possible to have the entire development team will work on the same module at the same time. So we need to design the software in such a way that different teams can work on different modules.

What are the Advantages of using SOLID Design Principles?

1. Achieve the reduction in complexity of the code
2. Increase readability, extensibility, and maintenance
3. Reduce error and implement Reusability
4. Achieve Better testability
5. Reduce tight coupling

What is the Single Responsibility Principle in C#?

The Single Responsibility Principle states that “Each software module or class should have only one reason to change“. In other words, we can say that each module or class should have only one responsibility to do.

So we need to design the software in such a way that everything in a class or module should be related to a single responsibility. That does not mean your class should contain only one method or property, you can have multiple members (methods or properties) as long as they are related to a single responsibility or functionality. So, with the help of SRP, the classes become smaller and cleaner and thus easier to maintain.

What is the Open-Closed Principle in C#?

https://dotnettutorials.net/lesson/open-closed-principle/

The Open-Closed Principle states that “software entities such as modules, classes, functions, etc. should be open for extension, but closed for modification“.

Let us understand the above definition in simple words. Here we need to understand two things. The first thing is Open for extension and the second thing is Closed for modification. The Open for extension means we need to design the software modules/classes in such a way that the new responsibilities or functionalities should be added easily when new requirements come. On the other hand, Closed for modification means, we should not modify the class/module until we find some bugs.

Implementation Guidelines for the Open-Closed Principle in C#

1. The easiest way to implement the Open-Closed Principle in C# is to add the new functionalities by creating new derived classes which should be inherited from the original base class.
2. Another way is to allow the client to access the original class with an abstract interface.
3. So, at any given point of time when there is a change in requirement or any new requirement comes then instead of touching the existing functionality, it’s always better and suggested to create new derived classes and leave the original class implementation as it is.

What is the Interface Segregation Principle in C#?

The Interface Segregation Principle states that “Clients should not be forced to implement any methods they don’t use. Rather than one fat interface, numerous little interfaces are preferred based on groups of methods with each interface serving one submodule“.

Let us break down the above definition into two parts.

1. First, no class should be forced to implement any method(s) of an interface they don’t use.
2. Secondly, instead of creating large or you can say fat interfaces, create multiple smaller interfaces with the aim that the clients should only think about the methods that are of interest to them.