单例 - 尝试初始化创建时的静态属性失败 [英] singleton - trying to initialise a static property on creation fails

问题描述

我有一个用于初始化error_handling的单例类。

I have a singleton class used to initialise error_handling.

类在参数中使用Zend_Config对象和可选的$ appMode，以允许覆盖定义的APPMODE常量当测试这个类。如果我创建具有非静态属性的对象，则一切正常，但初始化静态属性在调用通常的getInstance（）时不会按预期的方式工作。

The class as is takes a Zend_Config object and optional $appMode in parameter, to allow overriding the defined APPMODE constant when testing this class. All is fine if I create the object with non-static properties, but initialising a static property does not work the way I expected when calling the usual getInstance().

class ErrorHandling{

  private static $instance;
  private static $_appMode;  // not initialised in returned instance
  private $_errorConfig;

 private function __construct(Zend_Config $config, $appMode = null){

   $this->_errorConfig = $config;

   if(isset($appMode)){
       static::$_appMode = $appMode;
   }else{
         static::$_appMode = APPMODE;
   }  
 }

 private final function  __clone(){}

 public static function getInstance(Zend_config $config, $appMode = null){
     if(! (static::$instance instanceof self)){
         static::$instance = new static($config, $appMode);
     } 
     return static::$instance;
 }
}

不是我真的需要 $ _appMode根本就是静态的，我将其声明为私有并移动，但我仍然想知道是否可以从静态函数调用初始化静态属性。如果我真的需要静态$ _appMode，我可能会创建一个对象，然后使用setter方法设置该值，但这并不感觉为最好的方式。

Not that I really need $_appMode to be static at all, I declared it private and moved on, but I am still wondering if one can initialise static properties from a static function call. If I REALLY needed static $_appMode, I could probably create the object and set the value afterwards with a setter method but this doesn't "feel" as being the best way to do this.

推荐答案

结帐

<?

class ErrorHandling{

  private static $instance;
  private static $_appMode;  // not initialised in returned instance
  private $_errorConfig;

 private function __construct(array $config, $appMode = null){

   $this->_errorConfig = $config;

   if(isset($appMode)){
       self::$_appMode = $appMode;
   }else{
         self::$_appMode = APPMODE;
   }  
 }

 private final function  __clone(){}

 public static function getInstance(array $config, $appMode = null){
     if(! (self::$instance instanceof self)){
         self::$instance = new ErrorHandling($config, $appMode);
     } 
     return self::$instance;
 }

 public static function getAppMode() {
    return self::$_appMode;
 }
} 

$e = ErrorHandling::getInstance(array('dev' => true), -255);
var_dump($e, ErrorHandling::getAppMode());

这是你想要的吗？

你的可以在这里阅读关于 static 和 self之间的差异 - 晚期静态绑定

Your could read here about difference between static and self- late static binding

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