FactoryMethod

FactoryMethod

The good point over the SimpleFactory is you can subclass it to implement different ways to create objects. For simple cases, this abstract class could be just an interface. This pattern is a "real" design pattern because it achieves the dependency Inversion principle as known as the "D" in SOLID principles. It means the FactoryMethod class depends on abstractions, not concrete classes. This is the real trick compared to SimpleFactory or StaticFactory .

UML

Code

Vehicle.php

<?php

namespace Kuriv\PHPDesignPatterns\Creational\FactoryMethod;

abstract class Vehicle
{
    //
}

Bus.php

<?php

namespace Kuriv\PHPDesignPatterns\Creational\FactoryMethod;

class Bus extends Vehicle
{
    //
}

Car.php

<?php

namespace Kuriv\PHPDesignPatterns\Creational\FactoryMethod;

class Car extends Vehicle
{
    //
}

VehicleFactory.php

<?php

namespace Kuriv\PHPDesignPatterns\Creational\FactoryMethod;

interface VehicleFactory
{
    /**
     * Create vehicle.
     *
     * @param  void
     * @return Vehicle
     */
    public function createVehicle(): Vehicle;
}

BusFactory.php

<?php

namespace Kuriv\PHPDesignPatterns\Creational\FactoryMethod;

class BusFactory implements VehicleFactory
{
    /**
     * Create vehicle.
     *
     * @param  void
     * @return Vehicle
     */
    public function createVehicle(): Vehicle
    {
        return new Bus();
    }
}

CarFactory.php

<?php

namespace Kuriv\PHPDesignPatterns\Creational\FactoryMethod;

class CarFactory implements VehicleFactory
{
    /**
     * Create vehicle.
     *
     * @param  void
     * @return Vehicle
     */
    public function createVehicle(): Vehicle
    {
        return new Car();
    }
}

Test

FactoryMethodTest.php

<?php

namespace Kuriv\PHPDesignPatterns\Creational\FactoryMethod;

use PHPUnit\Framework\TestCase;

class FactoryMethodTest extends TestCase
{
    public function testCanCreateBus()
    {
        $busFactory = new BusFactory();
        $bus = $busFactory->createVehicle();
        $this->assertInstanceOf(Bus::class, $bus);
    }

    public function testCanCreateCar()
    {
        $carFactory = new CarFactory();
        $car = $carFactory->createVehicle();
        $this->assertInstanceOf(Car::class, $car);
    }
}