php – 编译错误：不能对表达式的结果使用isset()

发布时间：2020-12-13 22:36:26 所属栏目：PHP教程来源：网络整理

导读：我在从SF2.0.x迁移到SF2.7的应用程序中收到此错误： [1] SymfonyComponentDebugExceptionFatalErrorException: Compile Error: Cannot use isset() on the result of an expression (you can use "null !== expression" instead) at n/a in /var/www/htm

我在从SF2.0.x迁移到SF2.7的应用程序中收到此错误：

[1] SymfonyComponentDebugExceptionFatalErrorException: Compile Error: Cannot use isset() on the result of an expression (you can use "null !== expression" instead)
    at n/a
        in /var/www/html/reptooln_admin/app/cache/dev/twig/68/7f/63589dd3687cb849dd68e6b6c10aa99eda1d82f95a5f3ac52a864d200499.php line 39

我不知道什么是失败或如何解决这个问题所以我需要一些建议.这是报告Stacktrace的缓存文件中的行：

if ((((empty((isset($context["form_action"]) ? $context["form_action"] : $this->getContext($context,"form_action"))) == true) || (isnull((isset($context["form_action"]) ? $context["form_action"] : $this->getContext($context,"form_action"))) == true)) || (isset((isset($context["form_action"]) ? $context["form_action"] : $this->getContext($context,"form_action"))) == false))) {
                echo " ";
                $context["form_action"] = "";
                echo " ";

我有这个TwigExtension：

class PDOneTwigExtension extends Twig_Extension
{
    public function getFilters()
    {
        return array(
            'var_dump'   => new Twig_Filter_Function('var_dump'),'empty' => new Twig_Filter_Function('empty',array($this,'is_empty')),'isset' => new Twig_Filter_Function('isset','is_set')),'isnull' => new Twig_Filter_Function('isnull','is_null')),'ucfirst' => new Twig_Filter_Function('ucfirst','uc_first')),'ucwords' => new Twig_Filter_Function('ucwords','uc_words')),'count' => new Twig_Filter_Function('count','co_unt')),'sizeof' => new Twig_Filter_Function('sizeof','size_of')),'concat' => new Twig_Filter_Function('concat','concat')),'in_array' => new Twig_Filter_Function('in_array','inarray')),'array' => new Twig_Filter_Function('array','array_')),'add_to_array' => new Twig_Filter_Function('add_to_array','add_to_array')),'replace' => new Twig_Filter_Function('replace','replace')),'htmlentitydecode' => new Twig_Filter_Function('htmlentitydecode','htmlentitydecode'))
        );
    }

    public function is_empty($sentence)
    {
        return empty($sentence) ? true : false;
    }

    // rest of methods goes here

    public function getName()
    {
        return 'pdone_twig_extension';
    }
}

我在模板上使用如下：

{% if form_action|empty == true or form_action|isnull == true or form_action|isset == false %} {% set form_action = '' %} {% endif %}

问题出在哪里？有什么建议？

从 documentation开始：

isset() only works with variables as passing anything else will result in a parse error.

您没有直接将变量传递给isset().因此,您需要首先计算该值,将其分配给变量,然后将其传递给isset().

例如,您目前正在做的事情如下：

if(isset($something === false)) { } // throws a parse error,because $something === false is not a variable

你需要做的是：

$something = false;
if(isset($something)) { ... }

（编辑：李大同）

【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容!