PHP Inheritance

Introduction to Inheritance

Inheritance is a mechanism where a new class (child class or subclass) can inherit properties and methods from an existing class (parent class or superclass). This allows for code reuse and the creation of a hierarchical class structure.

Benefits of Inheritance

• Code Reusability: You can reuse existing code without rewriting it.
• Method Overriding: Child classes can provide specific implementations of methods defined in parent classes.
• Easy Maintenance: Changes made in the parent class automatically reflect in child classes.

Creating a Parent Class

To create a parent class, simply define a class with properties and methods that you want to be inherited:

<?php
class Animal {
    public $name;

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

    public function makeSound() {
        return "Some generic animal sound";
    }
}
?>

Creating a Child Class

To create a child class, use the extends keyword to inherit from the parent class:

<?php
class Dog extends Animal {
    public function makeSound() {
        return "Woof! My name is {$this->name}.";
    }
}

$dog = new Dog("Buddy");
echo $dog->makeSound(); // Outputs: Woof! My name is Buddy.
?>

Constructor Inheritance

Child classes can call the parent class's constructor using the parent:: keyword:

<?php
class Cat extends Animal {
    public function __construct($name) {
        parent::__construct($name); // Calling parent constructor
    }

    public function makeSound() {
        return "Meow! My name is {$this->name}.";
    }
}

$cat = new Cat("Whiskers");
echo $cat->makeSound(); // Outputs: Meow! My name is Whiskers.
?>

Accessing Parent Class Properties and Methods

Child classes can access public and protected properties and methods of the parent class:

<?php
class Bird extends Animal {
    public function getName() {
        return $this->name; // Accessing public property
    }
}

$bird = new Bird("Tweety");
echo $bird->getName(); // Outputs: Tweety
?>

Conclusion

Inheritance is a powerful feature of PHP that allows for efficient code organization and reuse. By creating parent and child classes, developers can build a structured and maintainable codebase.