Symfony\Component\DependencyInjection\Extension\ExtensionInterface::getAlias PHP Method

    public function getAlias();

 /**
  * Registers an extension.
  *
  * @param ExtensionInterface $extension An extension instance
  *
  * @api
  */
 public function registerExtension(ExtensionInterface $extension)
 {
     $this->extensions[$extension->getAlias()] = $extension;
     if (false !== $extension->getNamespace()) {
         $this->extensionsByNs[$extension->getNamespace()] = $extension;
     }
 }