How do you balance the trade-offs between extensibility and complexity when using the open-closed principle?

As the OCP separates stable, abstract parts from variable, concrete parts, you can modify or extend concrete components without impacting the stable interfaces, making the system easier to understand, test, and maintain. 🔗 Loose Coupling: Ensures components are independent with minimal dependencies. 🎯 High Cohesion: Keeps components focused with clear responsibilities.

Loose coupling and high cohesion are not some thing I know very well, but if I were to build a distributed system, I would definitely learn what they are and how to learn using them. I don’t find those two terms being used anywhere except for distributed systems. Of course I just studied spring and coupling is important there.

To me, OCP is just a strange explanation on how to create "framework code". Look at Windows Forms or WPF. You can use the existing components there. You can create your own components, but you do not have the source code of the frameworks (or, well, even if you have), you don't need to change the source code of those frameworks to be able to add your own components to your windows. If you create a "drawing framework" that draws circle and rectangles, but doesn't draw triangles or anything else... as long as you have the right abstractions, users can just create the Triangles and put that to be used by the framework, without having to change the framework itself. That is Open-Closed Principle (which was in practice way before the name).

Similarly, for any highly distributed application containing a lot of micro-services, if you have to structure the project, you will opt for a separate service layer and business layer. In such layers, its important to have a interfaces that define the contracts as generic as possible. Then the concrete classes implement those interfaces and provide the custom functionality. This is in line with the example stated above but for a larger complex application.

When applying the OCP with the strategy pattern, a common interface is defined for algorithms (e.g., payment methods) and concrete strategies are implemented (e.g., credit cards, PayPal). With this approach, you and yours can change behavior dynamically without altering existing code. 🔄 Strategy Pattern: Defines a family of algorithms, encapsulates them in separate classes, and makes them interchangeable at runtime. 🔧 Behavior Variation: Allows changing an object's behavior without modifying its class.

There are some patterns that you would never use unless you are dealing with a large system, and the strategy pattern is more commonly used in the past for gaming with different systems and very differently performing environments. Outside of that I think it would be hard for most people to know when the strategy pattern is used. There are some applications out there that still use different protocols to communicate with different operating systems on my payments is actually an architecture question because unless you were handling 100% of the payment system on a server connected to the same database, and everything else you may not use the strategy pattern. In fact, you might use two or three different applications already built in.

Using the OCP will provide you and your team with more flexibility, maintainability, and scalability, which will improve quality and readability. 💡 Avoids Code Duplication: Reduces errors by reusing and extending existing code. 🛠️ Enhances Testability & Maintainability: Isolates changes, minimizing impact on the rest of the system. 📈 Increases Modularity & Scalability: Adds functionality without disrupting existing features. 🔍 Improves Readability: Ensures code is clear and consistent, adhering to the principle of least surprise.

There used to be a code smell, where a programmer would leave executables or something else like a script in another language, waiting to be used. The strategy pattern, and the open closed principle simply describe the way you avoid a disorganized series of files. That is the practical aspect of using that pattern anyway. There were some systems where they were using classes and objects that could be changed at runtime, or where people were trying to use messaging to change behavior, but that sort of problem is so solved and learned in college projects now that it isn’t something that is really covered in at work or on a commonly used public educational website. And there is a good reason why coupling and the strategy pattern are paired.

The YAGNI (You Ain't Gonna Need It) principle can help you avoid over-complicating your designs and maintain a balance between flexibility and practicality while using OCP. ⚠️ Unnecessary Abstraction: Can add complexity or indirection that may not be needed. 🔄 Over-Engineering: Anticipating future requirements may lead to unnecessary complexity. 🧠 Increased Learning Curve: More abstract designs can increase cognitive load. 🚀 Performance Impact: Managing multiple objects may affect performance.

Oh yes, the YAGN principal causes some confusion at the small application level, where there are many factors to consider and different functionality to add in, and it isn’t so much about everything changing or needing the strategy pattern. If you have ever been on a private project where you are the only one working on something you would know what that is like. Outside of that I don’t know if it’s possible to teach people how to handle that kind of situation. Every design factor time limitation and effort limit some comes into play when you were building something on your own, and it clearly becomes the main challenge of your project over some 10000 lines of code, or 1000s.

Use OCP if it enhances quality without undue complexity; otherwise, refactor as needed. Agile practices help you and your design adapt effectively. 🔍 Project Nature & Scope: Use OCP more for large, complex, or dynamic projects; less for small, simple ones. 💡 Cost vs. Benefit: Weigh the value and quality added against complexity and overhead. 🔄 Feedback & Iteration: Agile methods, test-driven development, and continuous integration help refine OCP use based on real results.

Stealing from another answer long ago this is one of those experiences where you could build a chart with important variables, going from low to high and applying the OCP pattern and best practices change for a good reason, but not necessarily in one direction maybe two and with different results at different metrics of performance for the system an programmer. So the answer on how to use OCP is varied. That answer is stale and based on statistical analysis with obvious results. With the language, you can’t change and classes you can’t change once they are instantiated all of this applies. However, they might be some surprise over old languages or maybe new ones that if they are ever made that allow for changes to classes again.