如何在PHP闭包中使用$ this？ [英] How to use $this inside php closure?

问题描述

我有这样的代码：

class Foo {
   var $callbacks = array();
   function __construct() {
      $this->callbacks[] = function($arg) {
         return $this->bar($arg);
      };
   }
   function bar($arg) {
      return $arg * $arg;
   }
}

，我想在闭包中使用$ this，我尝试添加 use（$ this），但是抛出错误：

and I would like to use $this inside closures, I've try to add use ($this) but this throw error:

Cannot use $this as lexical variable

推荐答案

您不能使用 $ this ，因为这是对类实例本身的引用内的类的显式保留变量。复制到 $ this ，然后将其传递给 use 语言构造。

You cannot use $this as this is an explicit reserved variable for the class inside reference to the class instance itself. Make a copy to $this and then pass it to the use language construct.

class Foo {
   var $callbacks = array();
   function __construct() {
      $class = $this;
      $this->callbacks[] = function($arg) use ($class) {
         return $class->bar($arg);
      };
   }
   function bar($arg) {
      return $arg * $arg;
   }
}

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