PHP Objects And OOP

<?php

//Code/////////////////////////////////////////////////////////////////////

//Interface implementation in PHP.
interface IDrivable{
    public function drive($destination);
}

//Abstract class implementation in PHP.
abstract class Vehicle {
    //Force child class to make it's own implementation of this function.
    abstract protected function FillUpTank($fuel);

    //Child class will inherit this function and properties.
    
    //Properties.
    public $Mileage;
    public $Year;
    public $Model;

    public function GetCarStats(){
        echo "Mileage: " . $this->Mileage . " Year: " . $this->Year . " Model: " . $this->Model;
    }
}

//Class implementation in PHP.
class Car extends Vehicle implements IDrivable{

    //Constructor
    function __construct($mileage, $year, $model){
        //When referencing class mambers inside their class $this-> must be put infront.
        $this->Mileage = $mileage;
        $this->Year = $year;
        $this->Model = $model;
    }

    public $Fuel;

    //Implement FillUpTank from Vehicle.
    function FillUpTank($fuel){
        $this->Fuel += $fuel;
    }

    //Implement drive() from IDrivable interface.
    public function drive($destination){
        echo "Driving to " . $destination;
    }

    //Static class members don't need the class to be instantiated to be used.
    public static $VehicleType = "road vehicle";

    public static function GetVehicleType(){
        return Car::$VehicleType;
    }
}

////////////////////////////////////////////////////////////////////////////

//Entry point/////////////////////////////////////////////////////////////

//More about OOP in PHP: https://www.php.net/manual/en/language.oop5.php

echo Car::GetVehicleType();//:: is used to access static class members.
echo "<br>";

//Make new instance of Car.
$car = new Car(100000, 2010, "Some model...");

echo $car->Model;
echo "<br>";

$car->drive("somewhere...");
echo "<br>";

$car->GetCarStats();
echo "<br>";

////////////////////////////////////////////////////////////////////////////