Namespace with extends or interface causes Fatal Error without autoloader - php

Question

Why doesn't this work?
web/index.php (Not web/src/App/App.php)
<?php
namespace App;
// web/index.php
require_once __DIR__ . '/../vendor/autoload.php';
$app = new App();
class App extends \Silex\Application {
public function __construct()
{
parent::__construct();
echo 'Worked!';
}
}
I also tried namespace App {...}, no change. It throws this exception:
Fatal error: Uncaught Error: Class 'App\App' not found in /path/to/web/index2.php:8
Stack trace:
#0 {main}
thrown in /path/to/web/index2.php on line 8
As long as I remove the extends ... and the parent call part, it works. I also noticed interface does the same thing (trying to use Serializable). Is this an issue with the autoloader being confused? Is there a way to do this without putting the App\App class into a file in src\App\App.php?
Note: this is an exercise to build a single-file application with Silex, so "just put it in a file" isn't an answer. I want to know why this doesn't work, which has an answer.

Answer 1

The problem in your code is,
In namespace, You are initiating class object before it being declared and loaded. In your above code you are doing same thing,
1. You are initiating App class object which lies in App namespace
2. You are initiating class object at the moment class when is not yet declared(As it is defined below in your code).
In your above code, not even your loader be called. It will be called if you initiate App\App class object after its declaration. and If your loader does not work fine then afterwards you will possibly get this error.
Fatal Error: Silex\Application class not found
Please checkout some examples and findings.
Example 1 Here loader is expected to be called but not called, because you have registered after initialization of class($app = new App();).
Example 2 Here, calling class will look for autoloading class because here initialization takes place after registration of loader and declaration of class, which is probably answers your question.
Change your code with this to get it fix:
<?php
namespace App;
require_once __DIR__ . '/../vendor/autoload.php';
class App extends \Silex\Application {
public function __construct()
{
parent::__construct();
echo 'Worked!';
}
}
$app = new App();