我在Symfony项目上设置了以下配置:

twig:
    debug: '%kernel.debug%'
    strict_variables: '%kernel.debug%'
    globals:
      web_dir: "%kernel.root_dir%/../web"

我完成了以下细枝符号函数(如中所示 Symfony generate cdn friendly asset url ):

namespace AppBundle\Twig;

class AllExtentions extends \Twig_Extension
{
  public function getFunctions()
  {
      return array(
          new \Twig_SimpleFunction('versionedAsset',array($this,'versionedAsset'))
      );
  }


  /**
     * Gebnerate a cdn friendly url for the assets.
     * @param string $path The url of the path RELATIVE to the css.
     * @return string
     */
    public function versionedWebAsset($path)
    {
        // Set the value of the web_dir global
        // $webDir=
        $hash=hash_file("sha512",$path);
        return $path."?v=".$hash;
    }

}

我的问题是如何获得 web_dir 全局到versionedAsset函数?

编辑1

我使用Symfony的autowire,并自动连接/自动配置 AllExtentions 类别:

use Symfony\Component\DependencyInjection\Definition;
use Symfony\Component\DependencyInjection\Reference;

// To use as default template
$definition = new Definition();

$definition
->setAutowired(true)
->setAutoconfigured(true)
->setPublic(false);

$this->registerClasses($definition, 'AppBundle\\', '../../src/AppBundle/*', '../../src/AppBundle/{Entity,Repository,Resources,Tests}');