In software development, SOLID design principles are such a popular approach to programming for good reason. All five principles are commonly used by engineers and provide several important benefits through the stages of development. SOLID breaks down to:
S – Single-responsibility Principle
O – Open-closed Principle
L – Liskov Substitution Principle
I – Interface Segregation Principle
D – Dependency Inversion Principle
These standards are perfect for maintaining along with your project’s growth, as their goal is to allow developers to refine one aspect of software without impacting others. SOLID is intended to make designs clearer, and easier to maintain. Using these principles makes it easier on engineers to build adaptive, effective, and agile software without issues. If adhered to correctly, the SOLID approach can lead to better code for both readability and testability.
Single Responsibility Principle
- This approach makes code easier to test and software more straightforward to implement. Future modifications are less likely to have unintended consequences under the Single Responsibility Principle.
- Any changes to the features of a class that handles multiple responsibilities may impact others. This is difficult enough if you’re working on a simple program, but it can quickly escalate into a nightmare if you’re working with significant, enterprise-level software. You may save a lot of time testing and establishing a more maintainable design by ensuring that each module wraps only one task.
- Consider utilizing an automated check on build to limit the scope of classes to guarantee that you’re following this guideline in development. This check isn’t a surefire technique to ensure that you’re adhering to the single responsibility principle, but it can help ensure that classes aren’t breaking it.
- The open-closed concept states that existing, well-tested classes will need to be updated when any content must be added. Changing classes, on the other hand, can cause issues or bugs. This guideline must be followed to write code that is uncomplicated to maintain and revise.
- You should be able to use OOP features like inheritance via subclasses and interfaces to extend your existing code. However, it would help if you never changed existing classes, interfaces, or other code units in production, as this can result in unexpected behavior. When you add a new feature to your code by extending it rather than changing it, you reduce the chances of failure. Furthermore, you aren’t necessarily required to unit test existing features.
- A typical technique to comply with this guideline is to use inheritance or interfaces that allow polymorphic substitutions. This guideline should be followed for writing code that is manageable and revisable.
If adhered to correctly, the SOLID approach can lead to better code for both readability and testability.
Liskov Substitution Principle
- This concept states that all derived classes should be interchangeable with their parent classes. It’s an extension of the open-closed principle in that it ensures that derived classes extend the base class without affecting behavior.
- Objects from their subclasses should replace a superclass object without causing problems in the application. As a result, a child class should never change its parent class’s traits. The Liskov Substitution Principle can be implemented by paying attention to the correct inheritance hierarchy.
- This principle ultimately helps minimize unintended repercussions of changes and avoids the need to reopen a closed class to make changes. It allows for simple program additions. While it may slow down the development process, adhering to this approach can prevent a slew of problems during updates and extensions.
Interface Segregation Principle
- It is preferable to have many smaller interfaces rather than a few larger ones. This means that software engineers shouldn’t merely start with an existing interface and add additional methods. Instead, start by creating a new interface and then allow your class to implement as many as necessary.
- Code readability is harmed by violations of the Interface Segregation Principle, which causes programmers to design dummy methods that do nothing. You should avoid interface pollution in a well-designed application. The best approach is to build smaller interfaces that are more flexible to implement.
- Developers should opt for composition over inheritance and decoupling over coupling. Engineers should also strive for many client-specific interfaces rather than a single, general-purpose interface.
Engineers should also strive for many client-specific interfaces rather than a single, general-purpose interface.
Dependency Inversion Principle
- According to the dependency inversion concept, developers must “rely on abstractions, not concretions.” This principle is essential if you are decoupling high-level and low-level classes. Higher-level classes usually summarize complex logic, while low-level types include data or utilities.
- Typically, most users want to make high-level classes depending on low-level classes. Per the Dependency Inversion Principle, it is advised that you invert the dependency. Otherwise, the high-level class will also be affected when the low-level class is replaced.
- A dependency inversion design is only one prominent solution for adhering to this idea. Finding a way to apply this idea will make your code more agile in the long run.
Implementing SOLID design principles increases a code base’s overall complexity and results in a more flexible design. Apart from monolithic systems, SOLID design concepts may be applied to microservices, where each microservice can be treated as a separate code module. When SOLID design principles are adhered to throughout development, systems become more manageable, scalable, and reusable.
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