Introduction to Polymorphism in PHP

<?php

// Define a base class Person with name and age attributes
class Person {
    protected $name;
    protected $age;

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

    // Define a method to display details, meant to be overridden in derived classes
    public function display() {
        echo "Name: {$this->name}, Age: {$this->age}\n";
    }
}

// Define a derived class Student with a major attribute
class Student extends Person {
    private $major;

    public function __construct($name, $age, $major) {
        parent::__construct($name, $age);
        $this->major = $major;
    }

    // Override the display method to include the major attribute
    public function display() {
        parent::display();
        echo "Major: {$this->major}\n";
    }
}

// Define a derived class Teacher with a subject attribute
class Teacher extends Person {
    private $subject;

    public function __construct($name, $age, $subject) {
        parent::__construct($name, $age);
        $this->subject = $subject;
    }

    // Override the display method to include the subject attribute
    public function display() {
        parent::display();
        echo "Subject: {$this->subject}\n";
    }
}

// Create instances of Student and Teacher using parent class references
$person1 = new Student("Alice", 30, "Computer Science");
$person2 = new Teacher("Bob", 25, "Mathematics");

// Call the display method on the parent class references. The appropriate derived class method will be invoked.
$person1->display();
$person2->display();

?>