facade.md

Facade Design Pattern

The Facade design pattern provides a simplified interface to a more complex system, making it easier to use.

How to use

class Inventory
{
    public function checkAvailability(string $book): bool
    {
        echo "Checking availability of {$book}";
        return true;
    }
}

class Payment
{
    public function processPayment(float $amount): bool
    {
        echo "Processing payment of {$amount}";
        return true;
    }
}

class Shipping
{
    public function processShipping(string $book): void
    {
        echo "Shipping {$book} to the customer";
    }
}

class BookOrderFacade
{
    public function __construct(
        private Inventory $inventory = new Inventory(),
        private Payment $payment = new Payment(),
        private Shipping $shipping = new Shipping()
    ) {}

    public function processOrder(string $book, float $price): void
    {
        if ($this->inventory->checkAvailability($book)) {
            if ($this->payment->processPayment($price)) {
                $this->shipping->processShipping($book);
                echo "Order completed successfully for {$book}";
            }
        }
    }
}

Usage:

$orderFacade = new BookOrderFacade();
$orderFacade->processOrder("The lord of the Rings", 15.99);

Output:

Checking availability of The lord of the Rings
Processing payment of 15.99
Shipping The lord of the Rings to the customer
Order completed successfully for The lord of the Rings