CODEWITHSUNDEEP
phpsymfonysilex
Carvefx
Carvefx

Reputation: 448

PHP Silex microframework syntax explanation

I've been playing around with Silex for the past couple of days. I'm having trouble understand how the following code snippet works.

I'm not interested in what it does but rather how it does it.

    use Silex\Application;
    use Symfony\Component\HttpFoundation\Request;
    use Symfony\Component\HttpKernel\HttpKernelInterface;

    $app->get('/foo', function (Application $app, Request $request) {
       $subRequest = Request::create('/', ...);
       $response = $app->handle($subRequest, HttpKernelInterface::SUB_REQUEST, false);

        return $response;
    });

I get confused around

function (Application $app, Request $request)

From my understanding that's an anonymous function being called as an argument to the $app->get method. How do the two arguments in this anonymous function work? specifically what's:

Application $app, Request $request?

Thanks!

Upvotes: 1

Views: 615

Answers (1)

igorw
igorw

Reputation: 28259

The implicit way that controller arguments get populated is probably one of the most confusing parts of silex.

When you define a controller via one of the HTTP verb methods, that controller can add type hints to its arguments. Request and Application are type hints for the two arguments $app and $request.

The HttpKernel is the part of Silex responsible for invoking the controller. It uses a ControllerResolver to figure out which arguments to pass in. The ControllerResolver will infer the arguments from the type hints.

  • For a Silex\Application type hint, it will inject the application.
  • For a Symfony\Component\HttpFoundation\Request type hint, it will inject the current request.

If you want to get a better understanding, I recommend reading the HttpKernel source code.

Upvotes: 9

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