What's your strategy for preventing errors in object-oriented code?

Abstraction and encapsulation increase app security. Abstraction limits object exposure, preventing unauthorized access. Encapsulation protects object data and methods, ensuring data consistency. On the other hand, abstraction and encapsulation can be challenging and have trade-offs. Abstraction can complexify and slow down code, while encapsulation can increase dependencies and complexity.

Without further explanation, it is hard to tell how this will help. In particular, not exposing internal details and having methods that do the proper validations means we will have code that is resistant (if not immune) to invalid states, which is always the purpose. About abstraction... it's a little hard to tell, the bad usage of abstraction is actually a cause of errors, so I wouldn't give a suggestion of using abstraction and encapsulation as a general solution.

Single responsibility principle improves code testability, organization, and decoupling. However, defining the extent of a single responsibility and level of abstraction can be challenging. Open/closed principle can prevent errors and make code more flexible, but it can also lead to complexity, over-engineering, and performance issues. Liskov substitution principle can improve code consistency and avoid errors but may limit design choices and impose strict rules. Interface segregation principle can make your code more modular and flexible, but it may lead to more interfaces, code duplication, and reliance on multiple abstractions. Dependency inversion can improve code but may bring complexity and dependency injection.

This is over-stated. Most people don't understand the solid principles and trying to use them without proper understanding (and need) creates more trouble than solutions.

It is very important to have Solid understanding of these principles as these are crucial for code maintenance. The SOLID principles become valuable when altering existing code. Adhering to these principles result in fewer file modifications when adding new changes. The SOLID principles ensure that the changes are contained to few files. A clear indicator of not following these correctly is when a minor functionality change leads to a whole lot of files updated. Applying these principles correctly should result in smaller Pull requests.

Inheritance and polymorphism can help you achieve code reuse and maintainability, as well as support the principle of substitution, which states that a subclass object can be used wherever a superclass object is expected. However, they can also violate the principle of encapsulation, which states that an object should hide its internal details and only expose its interface. Abstract classes and interfaces are useful tools to define contracts and behaviours for subclasses. An abstract class is a class that cannot be instantiated but can have both abstract and concrete methods. Both abstract classes and interfaces can be used to achieve polymorphism by allowing subclasses to override or implement their methods.

Saying to prefer composition over inheritance is a sentence that just shows that, somehow, people think they serve the same purpose. We should not prefer composition over inheritance, because they serve different purposes. What happens is that a common error is abuse of inheritance, in which case the sentence makes some sense... but... you need a list... you don't inherit from one. You need a lock. You don't inherit from one. Using those "odd" analogies to real beings... you need a horse, you don't inherit from a horse. You only use inheritance when you have a reason to override an existing method (and that method needs to be a planned to be overridden method, which makes Java default of all methods are virtual a bad thing).

I was recently reviewing a Pull Request of another Dev. This a C# web project with a bunch of Controllers inheriting from a BaseController. The new change is to add new method that will be used by 2 out of 8 controllers. He has chosen Inheritance and added the new method in BaseController and had to inject another dependency in the constructor. This has resulted in updating all the controllers to inject the dependency to base constructor, though only 2 use the new method. This is a clear indicator of how not to use Inheritance. After a suggestion, it was changed to use composition which resulted in only updating the two controllers instead of all the controllers.

Design patterns provide you the guidelines to design your Object oriented applications and to avoid common recurring problems. While design patterns are powerful, they are not silver bullets. They should not be forced into places where they don't fit, for example using a Facade pattern for simple systems. They can quickly become Anti patterns if not used correctly. Its important to understand the problem you are trying to solve and choose the appropriate design pattern for that problem.

Design patterns are not fixed solutions that can be applied to any situation, but rather guidelines that can be adapted and modified according to the specific context and problem. Therefore, they require a good understanding of the underlying concepts and principles, as well as the trade-offs and limitations of each pattern. Design patterns can also help you cope with changing requirements and evolving technologies, by making your code more flexible and extensible. By using design patterns, you can reduce the impact of changes on your existing code, and add new features or functionalities without breaking or modifying the existing ones. Also, you can make your code more readable and understandable, as well as easier to maintain and debug.

This is your solution to any OOP code. In fact, any OOP code should use SOLID principles and Apply design patterns. Many design patterns are dying or being replaced by keywords that solve them accordingly. In general, patterns only exist because a language feature to do the same doesn't exist. Before templates/generics? Either use lists of void*/Object everywhere, or create a new implementation for each type (that's a pattern). With templates/generics... one implementation does the job. Method call pattern? You only need that in Assembler... use C, C++ etc, and at most you need a "calling convention" modifier. Observer pattern? I C# you use a one line event and have it done.

Testing and debugging can help you achieve higher customer satisfaction and trust, as well as lower maintenance costs and risks, by delivering a reliable and secure software product that meets the user's expectations and needs as well as can help you follow the best practices and principles of object-oriented programming, such as abstraction, encapsulation, inheritance, and polymorphism, by ensuring that your code is consistent, coherent, and adheres to the design specifications.

I would say nothing to discuss here... but I do... Write meaningful tests. One issue I saw in many places that try to get 100% code coverage is that: 1. They need write one unit test for every parameter, just to pass an invalid value and see that it properly fails; 2. They start to REMOVE input validations, as those consume too much development time, testing time and make navigating test files a nightmare, actually hiding the places with real bugs. Bug... item 2 becomes a new source of bugs... So... test wisely!

It's mainly depend on error type in OOPS. If error generated because of system failure we can not control it via a oops error handling but if it's not system failure so we can controll it using exception handling macachnism. And more thing if we have real life OOPs example and we know every thing about that, then it would be more easily to handle it like both system and non system error handling.