When should you prefer inheritance and when should you avoid it?

Inheritance is a fundamental concept in object-oriented programming that allows a class to inherit properties and methods from another class. However, it is essential to understand when to use inheritance effectively and when to avoid it to maintain clean, manageable, and flexible code.

When to Prefer Inheritance

• Code Reusability: Use inheritance when you want to reuse code across multiple classes. For instance, if you have a number of classes that share a common behavior.
• Hierarchical Classification: Choose inheritance when representing a hierarchy, where a subclass is a specialized version of a superclass.
• Polymorphism: Inheritance allows for polymorphic behavior, enabling you to treat objects of different classes through a common interface.

When to Avoid Inheritance

• Tight Coupling: Avoid inheritance when it leads to tightly coupled classes, making your code more difficult to maintain and test.
• Implementation Inheritance vs. Interface Inheritance: Prefer composition over inheritance when you need to adhere to the principle of separation of concerns.
• Fragile Base Class Problem: Be cautious with inheritance as changes in a superclass can inadvertently affect subclasses, leading to bugs.

Example

// Base class
class Animal {
    public function makeSound() {
        return "Generic animal sound";
    }
}

// Derived class
class Dog extends Animal {
    public function makeSound() {
        return "Bark";
    }
}

// Using the classes
$dog = new Dog();
echo $dog->makeSound(); // Outputs: Bark