GlobalVariables.php

<?php

namespace Diveshare\DiveshareBundle\Templating;

/**
 * Additional helpful methods that is needed in templates.
 *
 * @package DiveshareBundle
 */
class GlobalVariables extends \Symfony\Bundle\FrameworkBundle\Templating\GlobalVariables
{
    /**
     * For use in a twig template with `{% extends app.pjax ? 'empty.twig' : 'base.twig' %}` so it is possible to serve up a chromeless 
     * rendering.
     *
     * @return Boolean
     */
    public function isPjax()
    {
        if ($request = $this->getRequest() && $request->server->has('X-PJAX')) {
            return true;
        }

        return false;
    }
}

better than replacing the global variable set by the framework (as you cannot do it several times): register a new one