PHP Inheritance

PHP Inheritance – Extend Classes & Reuse Code 🚀

Inheritance allows a class (child) to inherit properties and methods from another class (parent). This helps in code reuse and maintaining cleaner code.

In PHP, inheritance is done using the extends keyword.

🔹 Basic PHP Inheritance

When a child class inherits from a parent class, it gets access to all public and protected properties and methods.

📝 Example 1: Simple Inheritance

<?php
// Parent class
class Animal {
    public $name;

    public function setName($name) {
        $this->name = $name;
    }

    public function getName() {
        return "This is a " . $this->name;
    }
}

// Child class inheriting from Animal
class Dog extends Animal {
    public function bark() {
        return "Woof! Woof! 🐶";
    }
}

// Creating an object of Dog
$myDog = new Dog();
$myDog->setName("Golden Retriever");

echo $myDog->getName(); // ✅ Inherited from Animal
echo "<br>";
echo $myDog->bark(); // ✅ Method from Dog class
?>

The Dog class inherited the methods from the Animal class. It also has its own method bark().

🔹 Overriding Parent Methods

A child class can override a method from the parent class by redefining it.

📝 Example 2: Method Overriding

<?php
class Vehicle {
    public function start() {
        return "Vehicle is starting... 🚗";
    }
}

// Child class overrides the start method
class Car extends Vehicle {
    public function start() {
        return "Car is revving up! 🚀";
    }
}

$myCar = new Car();
echo $myCar->start(); // Output: Car is revving up!
?>

Here, the Car class overrides the start() method of the Vehicle class.

🔹 Using Parent Methods in Child Class

The parent:: keyword lets you call a method from the parent class inside the child class.

📝 Example 3: Calling Parent Methods

<?php
class Laptop {
    public function start() {
        return "Laptop is booting up... 💻";
    }
}

class GamingLaptop extends Laptop {
    public function start() {
        return parent::start() . " Loading games! 🎮";
    }
}

$gamerPC = new GamingLaptop();
echo $gamerPC->start(); // ✅ Calls parent method + child method
?>

We used parent::start() inside the child class to call the method from the parent class.

🔹 Protected Properties & Methods in Inheritance

The protected keyword allows child classes to access properties/methods while keeping them hidden from outside the class.

📝 Example 4: Using Protected Properties

<?php
class Person {
    protected $name;

    public function setName($name) {
        $this->name = $name;
    }
}

// Child class can access protected properties
class Employee extends Person {
    public function getName() {
        return "Employee Name: " . $this->name;
    }
}

$emp = new Employee();
$emp->setName("John Doe");
echo $emp->getName(); // ✅ Works fine
?>

The $name property is protected, so it’s accessible in the child class but not outside the class.

🎯 Key Takeaways

• extends → Used to inherit a class.
• Child classes inherit public & protected properties/methods.
• Child classes can override parent methods.
• Use parent::method() to call a parent method inside a child class.
• Private properties/methods are not inherited.

📝 Practice Time!

Try creating a Superhero class 🦸 that inherits from a Human class and adds special powers!