The SOLID theory was introduced by Robert Cecil Martin also known as Uncle Bob at the beginning of the 2000s. The name SOLID is a mnemonic acronym for five principles in Object Oriented Programming used to design manageable clear code. Today SOLID approach is widely used by the development teams worldwide providing their customers with quality.
What principles does the SOLID theory include?
- Single Responsibility Principle (SRP)
A class should have one, and only one, reason to change. SRP is a fundamental principle that is mostly related to requirements changes. The main idea here is that every single structure in code should be responsible for only one single purpose. This way SRP simplifies the way of dealing with requirements that are likely to change within the software development process than others. Such requirements usually include user interface design, input/output protocols, data exchange schemas and so on.
- Open / Closed Principle (OCP)
You should be able to extend a classes behavior, without modifying it. OCP refers to a prohibition on changing the source code of a software project. It means that a team shouldn’t modify the source code to change or extend functionality. Instead, the Open / Closed Principle offers developers to use alternative implementations like interfaces and abstract classes. This way once your team has written and tested the source code, its quality will remain the same regardless of functionality changes.
- 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. The third principle called LSP was formulated by Barbara Liskov and considered to be one of the most difficult to understand. It says that classes should be designed in a way that allows substituting dependencies with subclasses (without the client knowing about the change). In simple words, subclasses should match the methods and properties of the base class to make a substitution of dependencies possible. It makes code reusable and easier to maintain.
- Interface Segregation Principle (ISP)
A client should never be forced to implement an interface that it doesn’t use or clients shouldn’t be forced to depend on methods they do not use. ISP is focused on breaking large interfaces into smaller multiple ones to minimize dependencies and make interfaces easier to manage. Instead of using non-cohesive interfaces, ISP recommends creating multiple and small ones. It minimizes direct dependencies improving flexibility and increasing robustness.
- Dependency Inversion Principle (DIP)
High level modules should not depend upon low level modules. Both should depend upon abstractions. Abstractions should not depend upon details. Details should depend upon abstractions. The idea of DIP refers to removing direct dependency between low and high level modules that creates a hierarchy structure of the classes. In programming, high level classes deal with business logic, large sets of functionality and overall design. Low level classes are focused on specific features. DIP allows classes to refer to their dependencies using abstractions – interfaces or abstract classes. This way changes you are making on different levels don’t impact the whole software structure.
What benefits can you actually get for your software project as a business owner?
SOLID principles provide guidelines for software developers helping them to built quality robust code but what does it mean for you.
SOLID principles allow engineers to identify and fix problems in code easier saving your time and money. Tightly focused classes in code are simpler to test which minimizes class containing bugs and makes code more robust. Thanks to the OCP QA team needs to perform testing activities for your source code only once that helps to avoid appearing of new bugs regardless of functionality extension.
Clear manageable code
Following SOLID principles helps to keep code organized throughout the development process. Classes responsible for one purpose are more manageable as you don’t have to keep multiple elements inside the class connected. Instead of this you create different classes that work together and can deal with more complex tasks. This way your software is able to perform advanced functionality.
SOLID principles provide reusability of programming components that makes integration of new objects easier. You can extend the functionality of your app and make changes easier without rewriting code on multiple levels. It perfectly suits for software development using Agile frameworks where changing requirements are welcomed. SOLID principles also help to provide simpler onboarding for new specialists joining your team. Remember that the SOLID approach is suitable for projects developing from scratch, not for existing ones.
SOLID principles give names to specific concepts that help team members to have a substantive conversation on project issues both with stakeholders and each other. This way you can easily categorize the development issues as good or bad ones accelerating the process of finding the right solutions. By the way, Robert C. Martin himself called SOLID principles common-sense solutions to common problems that can help you stay out of trouble.
SOLID principles help developers to create your software project step-by-step focusing on the quality and performance of your platform. Exposit engineers have experience in applying SOLID principles to the development of custom software solutions. If you are planning to build a software platform for your business, we are ready to provide you with the full range of services using the most suitable methodologies and approaches.