If someone would ask me about my favorite keyword in PHP, I would certainly answer: final. It doesn’t mean I write this modifier in each class or method. It not only shows the intention but also provides a mechanism to protect the code. At least from the assumption.
The final keyword can be used both on the class level and on the method level. It prevents future extension of functionalities in a non-effective way. If a class is marked as final, then we can’t inherit from it. If a method is marked as final, we can’t override it.
The theory sounds good. Let’s go to details.