Facade

Facade Design Pattern

A Facade is an outward appearance that conceals a less pleasant reality. In this project we use the facade design pattern to abstract away the inner workings of the Shipment Gateway and Payment Gateway. This allows us to hide the implementation details behind well known endpoints on which our core business logic can depend on. This enables us to reduced dependencies of outside code, allows more flexibility to switch providers, and reduces our code exposure to undesirable design patterns, such as the singleton design pattern extensively used in these 3rd party PHP libraries: EasyPost and Stripe.

Example

Stripe Payment Gateway

class Stripe implements PaymentGatewayInterface
{
    public function __construct($apiKey)
    {
        \Stripe\Stripe::setApiKey($apiKey);
    }

    public function createCharge(ChargeRequest $chargeRequest)
    {
        $card = $chargeRequest->getCreditCard();

        return \Stripe\Charge::create([
            'amount' => $chargeRequest->getAmount(),
            'currency' => $chargeRequest->getCurrency(),
            'card' => [
                'name' => $card->getName(),
                'address_zip' => $card->getZip5(),
                'number' => $card->getNumber(),
                'cvc' => $card->getCvc(),
                'exp_month' => $card->getExpirationMonth(),
                'exp_year' => $card->getExpirationYear(),
            ],
            'description' => $chargeRequest->getDescription(),
        ]);
    }
}