Question

以下代码在PHP 5.3中无效

class DatabaseConfiguration {

    public $development = array("user" => "dev");

    public $production = array("user" => "prod");

    public $default =& $this->development;

}

似乎$default只能用编译时常量初始化。它是在任何PHP文档中声明的吗？可以在不依赖构造函数的情况下$default进行初始化吗？

Answer 1

来自PHP documentation：

这个声明可能包括初始化，但是这个初始化必须是常量值 - 也就是说，它必须能够在编译时进行评估，不得依赖于运行时信息以便进行评估。

Answer 2

您可以考虑使用方法返回别名属性值...

class DatabaseConfiguration
{    public $development = array("user" => "dev");

     public $production = array("user" => "prod");

     // Method to define $this->default property as an alias of $this->development
     private function default(){return $this->development;}

     public function __get($name)
     {    if(property_exists($this,$name)){return $this->$name;}
          if(method_exists($this,$name)){return $this->$name();}
          throw new ErrorException('This property does not exist',42,E_USER_WARNING);
     }
}

在定义时对属性进行别名化

2 个答案: