PHP使用$ this当不在对象上下文 [英] PHP using $this when not in object context

问题描述

我有以下类：

  class Decode {
 public $ code; 
 public $ codeStore; 
 public $ store; 
 public $ varName; 
 public $ storeNew = array（）; 
 public $ storeNew = array（）; 
 
 public function __construct（$ code）{
 $ this-> code = $ code; 
 $ this-> codeStore = $ code; 
 $ this-> varName = substr（$ this-> code，0，30）; 
 $ this-> varName = str_replace（var，，$ this-> varName）; 
 $ this-> varName = substr（$ this-> varName，0，strpos（$ this-> varName，= [\））; 
} 
 
 public function chrToVar（）{
 //下面的行是第38行
 $ this-> code = preg_replace_callback（'/'.$ this-> varName.'\ [ （[0-9] +）\] /'，function（$ matches）{return $ this-> storeNew [$ matches [1]];}，$ this-> code）; 
} 
} 
 
 $ script = new Decode（'stuff'）; 
 $ script-> chrToVar（）; 
  pre> 
 
 
当我运行这个代码，我得到以下错误：
 
 
致命错误：在第38行的
 /var/www/programs/decode.php中不在对象上下文中时使用$ this 
 
 
为什么会发生这种情况？我想它与具有 preg_replace_callback 中的函数的参数有关，但我不知道如何解决它。
解决方案
您得到此错误的原因是由于范围。您定义的匿名函数有自己的范围，范围。为了使它工作，你必须传递variale  $ this 到函数。这可以类似如下：
  function（）use（$ this）{... 
  
希望它有帮助。
 
I have the following class:
class Decode {
    public $code;
    public $codeStore;
    public $store;
    public $varName;
    public $storeNew = array();
    public $storeNew = array();

    public function __construct($code) {
        $this->code = $code;
        $this->codeStore = $code;
        $this->varName = substr($this->code, 0, 30);
        $this->varName = str_replace("var ", "", $this->varName);
        $this->varName = substr($this->varName, 0, strpos($this->varName, "=[\""));
    }

    public function chrToVar() {
        // The line below is line 38
        $this->code = preg_replace_callback('/'.$this->varName.'\[([0-9]+)\]/', function($matches) { return $this->storeNew[$matches[1]]; }, $this->code);
    }
}

$script = new Decode('stuff');
$script->chrToVar();
When I run this code, I get the following error:

  
Fatal error: Using $this when not in object context in
  /var/www/programs/decode.php on line 38
Why is this happening? I suppose it has something to do with the parameter that has the function in preg_replace_callback, but I have no idea how to fix it.
解决方案
The reason you are getting this error is because of scope. The anonymous function you have defined has its own scope that is separate from the class scope. So to make it work you have to pass the variale $this to the function. This can be like the following:
function() use ($this) {...
Hope it helps.

                        
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