Symfony's magic: dependency injection

Injecting dependencies is a fundamental principle that is recommended by various approaches, including SOLID.

More pragmatically, instead of doing this:

namespace App\Services;

class MyService {
    private $myDependency;

    public function __construct()
    {
        $this->myDependency = new MyDependency();
    }
}

You can do that (PHP 8):

namespace App\Services;

class MyService {

    public function __construct(private MyDependency $myDependency)
{}
}

However, you may wonder why it's better and how it works behind the scene.

Injections …

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