decorator.md

Decorator pattern

Stack on behaviour to an existing class dynamically Useful when you want to preform some action somewhere, but somewhere not Decorators exclude the need for creating different classes for doing basicaly the same thing, with only one or two functionalities more They should all adhere to the same interface

WITHOUT decorator

class BasicInspection
    {
        public function getCost()
        {
            return 19;
        }
    }

    class BasicInspectionAndOilChange
    {
        public function getCost()
        {
            return 19 + 19;
        }
    }

    class BasicInspectionAndOilChangeAndTireRotation
    {
        public function getCost()
        {
            return 19 + 19 + 10;
        }
    }

    echo (new BasicInspection)->getCost();
    echo (new BasicInspectionAndOilChange)->getCost();
    echo (new BasicInspectionAndOilChangeAndTireRotation)->getCost();

WITH decorator

interface CarService
{
    public function getCost();

    public function getDescription();
}

class BasicInspection implements CarService
{
    public function getCost()
    {
        return 19;
    }

    public function getDescription()
    {
        return 'Basic Inspection';
    }
}

class OilChange implements CarService
{
    protected $carService;

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

    public function getCost()
    {
        return 29 + $this->carService->getCost();
    }

    public function getDescription()
    {
        return $this->carService->getDescription() . 'and oil change';
    }
}

class TireRotation implements CarService
{
    protected $carService;

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

    public function getCost()
    {
        return 15 + $this->carService->getCost();
    }

    public function getDescription()
    {
        return $this->carService->getDescription() . 'and tire rotation';
    }
}

echo (new TireRotation(new OilChange(new BasicInspection())))->getCost();

$service = new OilChange(new TireRotation(new BasicInspection));
echo $service->getDescription();