PHP interfaces are a blueprint of a class, that defines a set of methods that must be implemented in the class that implements the interface. The interface allows you to define what methods a class should implement without providing the actual implementation, which enforces a contract between different classes and ensures that they have a common set of methods.
Declaration of an interface requires, the usage of the keyword “interface” followed by the interface name and a block of method signatures.
Let’s look at an example(PHP/Laravel):
PaymentGatewayInterface.php
Create an interface that specifies the required methods.
<?php
namespace App\Interfaces;
interface PaymentGatewayInterface {
public function pay($amount);
public function refund($paymentId, $amount);
}
PaypalPaymentGateway.php
Now let’s implement the interface by creating a new class that defines the methods specified in the interface.
<?php
namespace App\Services;
use App\Interfaces\PaymentGatewayInterface;
class PaypalPaymentGateway implements PaymentGatewayInterface
{
public function pay($amount)
{
// Implementation of payment gateway logic here
}
public function refund($paymentId, $amount)
{
// Implementation of refund logic here
}
}AppServiceProvider.php
Before you use this interface in the controller, let’s register it in AppServiceProvider.
<?php
namespace App\Providers;
use App\Interfaces\PaymentGatewayInterface;
use App\Services\PaypalPaymentGateway;
use Illuminate\Support\ServiceProvider;
class AppServiceProvider extends ServiceProvider
{
/**
* Register any application services.
*/
public function register(): void
{
$this->app->bind(PaymentGatewayInterface::class, PaypalPaymentGateway::class);
}
}
PaymentController.php
Use the interface by creating a new instance of the class that implements the interface
<?php
namespace App\Http\Controllers;
use App\Interfaces\PaymentGatewayInterface;
use App\Services\StripePaymentGateway;
class PaymentController extends Controller
{
protected PaymentGatewayInterface $gatewayService;
public function __construct(PaymentGatewayInterface $gatewayService) {
$this->gatewayService = $gatewayService;
}
public function makePayment()
{
$this->gatewayService->pay(100);
}
}That’s it, this was the simplest way of implementing the interface in PHP/Laavel.
