PHP Inheritance Overview

In PHP, inheritance is a fundamental object-oriented programming (OOP) concept that allows you to build a new class on top of an existing one. The new class, known as the "child" or "derived" class, inherits the current class's properties and methods, known as the "parent" or "base" class. This allows for code duplication and supports a hierarchical class organisation.

In PHP, you use the extends keyword to indicate that a class is descended from another class. The child class can then access all of its parent class's non-private properties and methods.

The basic syntax for defining inheritance in PHP is as follows:

class CFParentClass {
    // properties and methods of the parent class
}

class CFChildClass extends CFParentClass {
    // properties and methods of the child class
}

Let's see a practical example to understand this better:

class CFAnimal {
    public $name;
    
    public function __construct($name) {
        $this->name = $name;
    }
    
    public function CFmakeSound() {
        return "Animal sound";
    }
}

class CFDog extends CFAnimal {
    public function CFmakeSound() {
        return "Woof!";
    }
}

// Creating instances of the classes
$animal = new CFAnimal("Generic Animal");
$dog = new CFDog("Buddy");

// Using inherited properties and methods
echo $animal->name; // Output: Generic Animal
echo $dog->name; // Output: Buddy

echo $animal->makeSound(); // Output: Animal sound
echo $dog->makeSound(); // Output: Woof!

In the above example, the Dog class derives from the Animal class. The Dog class overrides the makeSound() method, providing its own implementation of the method while retaining the Animal class's name attribute.

Inheritance enables the creation of specialised classes that share common functionality with their parent classes, facilitating code reuse and a disciplined approach to object-oriented programming. Remember that the parent class's private properties and methods are not available in the child class. You can use protected or public visibility instead to restrict access to these properties or methods.

Hope you enjoy this tutorial.