php – 编译错误:不能对表达式的结果使用isset()

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我在从SF2.0.x迁移到SF2.7的应用程序中收到此错误
  1. [1] Symfony\Component\Debug\Exception\FatalErrorException: Compile Error: Cannot use isset() on the result of an expression (you can use "null !== expression" instead)
  2. at n/a
  3. 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:

  1. 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))) {
  2. echo " ";
  3. $context["form_action"] = "";
  4. echo " ";

我有这个TwigExtension:

  1. class PDOneTwigExtension extends \Twig_Extension
  2. {
  3. public function getFilters()
  4. {
  5. return array(
  6. 'var_dump' => new \Twig_Filter_Function('var_dump'),'empty' => new \Twig_Filter_Function('empty',array($this,'is_empty')),'isset' => new \Twig_Filter_Function('isset','is_set')),'isnull' => new \Twig_Filter_Function('isnull','is_null')),'ucfirst' => new \Twig_Filter_Function('ucfirst','uc_first')),'ucwords' => new \Twig_Filter_Function('ucwords','uc_words')),'count' => new \Twig_Filter_Function('count','co_unt')),'sizeof' => new \Twig_Filter_Function('sizeof','size_of')),'concat' => new \Twig_Filter_Function('concat','concat')),'in_array' => new \Twig_Filter_Function('in_array','inarray')),'array' => new \Twig_Filter_Function('array','array_')),'add_to_array' => new \Twig_Filter_Function('add_to_array','add_to_array')),'replace' => new \Twig_Filter_Function('replace','replace')),'htmlentitydecode' => new \Twig_Filter_Function('htmlentitydecode','htmlentitydecode'))
  7. );
  8. }
  9.  
  10. public function is_empty($sentence)
  11. {
  12. return empty($sentence) ? true : false;
  13. }
  14.  
  15. // rest of methods goes here
  16.  
  17. public function getName()
  18. {
  19. return 'pdone_twig_extension';
  20. }
  21. }

我在模板上使用如下:

  1. {% 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?

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:

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

你需要做的是:

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

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