SOLID Design Principles Elaborated - Programming

solid design principles

The SOLID are long-standing principles used to manage most of the software design problems you encounter in your daily programming process. So, following SOLID principles, ensures the system design is as clean and scalable as possible.

Whether you are designing or developing the application, you can take the following advantages of SOLID principles to write code in the right way.


So far, maintenance is very vital for any organization to keep high quality as a standard in software development. 


When you design and develop a large-scale application, it's essential to build one that is easily testable.

Flexibility and scalability: 

Flexibility and scalability are the most crucial parts of enterprise application systems, so the system design should be adaptable to any later update and extensible for adding new features smoothly and efficiently.

Parallel development:

 Parallel development is one of the key factors for saving time and costs in the software development process. It could be challenging for different developers to work on the same module at the same time. To work independently and simultaneously software needs to be broken down into various modules and components.

There are five design principles in Programming:

1. Single Responsibility Principle (SRP)

2. Open Closed Principle (OCP)

3. Liskov Substitution Principle (LSP)

4. Interface Segregation Principle (ISP)

5. Dependency Inversion Principle (DIP)

1. Single Responsibility Principle (SRP)

A class should have only one reason to change.

A class should not be loaded with multiple responsibilities or functionalities and a single responsibility should not be spread across multiple classes or mixed with other responsibilities. When there is a need to change in the future, the more changes the class needs to apply.

2. Open Closed Principle (OCP)

Software entities (classes, modules, functions, etc.) should be open for extension but closed for modification.

When there is a need of adding a new feature, extensibility is very efficient as it does not disturb previous running applications.

3. Liskov Substitution Principle (LSP)

Functions that use pointers or references to base classes must be able to use objects of derived classes without knowing it.

4. Interface Segregation Principle (ISP)

No client should be forced to implement methods that it does not use, and the contracts should be broken down into thin ones.

5. Dependency Inversion Principle (DIP)

This principle is about dependencies among components. High-level modules should not depend on low-level modules. Both should depend on abstractions.

Abstractions should not depend on details. Details should depend on abstractions.


The five SOLID principles discussed above are the base for Object Oriented design. Most of the SOLID principles involved are responsible for adding a layer of abstraction between classes that would otherwise depend on each other, Thus creating a loose coupling relationship that results in less rigid and fragile code. 

It is always recommended to keep these principles in mind when writing new code.

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