If you don't know the difference in PHP between the self and the static keywords, then here is a dummy example for you. https://3v4l.org/HBXAe

index.php

<?php


class Vehicle {

  /**
   * @var string
   */
  private $name;


  protected static $type = 'vehicle';

  /**
   * Vehicle constructor.
   *
   * @param $name
   */
  public function __construct($name) {
    $this->name = $name;
  }

  /**
   * @param $type
   * @return static
   */
  public static function createStatic($type) {
    return new static($type);
  }

  /**
   * @param $type
   * @return \Vehicle
   */
  public static function createSelf($type) {
    return new self($type);
  }

  /**
   * @return string
   */
  public function getStaticType() {
    return static::$type;
  }

  /**
   * @return string
   */
  public function getSelfType() {
    return self::$type;
  }
}

class Bicycle extends Vehicle {

  protected static $type = 'bicycle';

  /**getSelfType
   * @inheritDoc
   */
  public function __construct($name) {
    parent::__construct($name);
  }
}

class Car extends Vehicle {

  protected static $type = 'car';

  /**
   * @inheritDoc
   */
  public function __construct($name) {
    parent::__construct($name);
  }
}

$vehicle = new Vehicle('vehicle1');
$bicycle = new Bicycle('bicycle1');
$car = new Car('car1');

var_dump('new Vehicle(\'vehicle\') is a ' . get_class($vehicle));
var_dump('new Bicycle(\'bicycle\') is a ' . get_class($bicycle));
var_dump('new Car(\'car\') is a ' . get_class($car));
var_dump('$car->getSelfType() is ' . $car->getSelfType());
var_dump('$car->getStaticType() is ' . $car->getStaticType());


$staticThing1 = Vehicle::createStatic('staticThing1');
$staticThing2 = Bicycle::createStatic('staticThing2');
$staticThing3 = Car::createStatic('staticThing3');

var_dump('Vehicle::createStatic(\'staticThing1\') is a ' . get_class($staticThing1));
var_dump('Bicycle::createStatic(\'staticThing2\') is a ' . get_class($staticThing2));
var_dump('Car::createStatic(\'staticThing3\') is a ' . get_class($staticThing3));
var_dump('$staticThing3->getSelfType() is ' . $staticThing3->getSelfType());
var_dump('$staticThing3->getStaticType() is ' . $staticThing3->getStaticType());

$selfThing1 = Vehicle::createSelf('selfThing1');
$selfThing2 = Bicycle::createSelf('selfThing2');
$selfThing3 = Car::createSelf('selfThing3');

var_dump('Vehicle::createSelf(\'selfThing1\') is a ' . get_class($selfThing1));
var_dump('Bicycle::createSelf(\'selfThing2\') is a ' . get_class($selfThing2));
var_dump('Car::createSelf(\'selfThing3\') is a ' . get_class($selfThing3));
var_dump('$selfThing3->getSelfType() is ' . $selfThing3->getSelfType());
var_dump('$selfThing3->getStaticType() is ' . $selfThing3->getStaticType());

output.txt

new Vehicle('vehicle') is a Vehicle

new Bicycle('bicycle') is a Bicycle

new Car('car') is a Car

$car->getSelfType() is vehicle

$car->getStaticType() is car

Vehicle::createStatic('statisThing1') is a Vehicle

Bicycle::createStatic('statisThing2') is a Bicycle

Car::createStatic('statisThing3') is a Car

$staticThing3->getSelfType() is vehicle

$staticThing3->getStaticType() is car

Vehicle::createSelf('selfThing1') is a Vehicle

Bicycle::createSelf('selfThing2') is a Vehicle

Car::createSelf('selfThing3') is a Vehicle

$selfThing3->getSelfType() is vehicle

$selfThing3->getStaticType() is vehicle