是否可以通过调用Twig_SimpleFunction来修改当前的Twig上下文？我注册了以下功能:new\Twig_SimpleFunction('setContextVar',array($this,'setContextVar'),array('needs_context'=>true)),);}publicfunctionsetContextVar($context,$str,$val){$context['context'][$str]=$val;var_dump(array_keys($context['context']));}}当从类似{{setContextVar('