public function call( &$environmentArguments = array(), $isPackeStage = false  )
    {
        if ( $this->isTemplateFunction )
        {
            $tpl = eZTemplate::factory();
            $tpl->setVariable( 'arguments', $this->functionArguments );
            $tpl->setVariable( 'environment', $environmentArguments );
            return $tpl->fetch( 'design:' . $this->className . '/' . $this->functionName . '.tpl' );
        }
        else
        {
            return call_user_func_array( array( $this->className, $this->functionName ), array( $this->functionArguments, &$environmentArguments, $isPackeStage ) );
        }
    }