Php 静态方法-调用函数

首先调用factory（），然后调用构造函数，最后调用execute（）。当然，这是意料之中的事

请求类包含两个非静态属性。我把它们都设置为工厂方法。像这样：

echo System\Core\Request::factory()->execute();

接下来是构造函数：

public static function factory()
{
   if(! Request::$initial)
   {
      $request = Request::$initial = Request::$current = new Request();
      $request->foo = 'bar';
   }
   else
   {
      Request::$current = $request = new Request();
      $request->foo = 'aaa';
   }
   return Request::$current;
}

---

发生了什么？

在您设置

foo

之前调用构造函数，因为您在实例化请求后在工厂中设置了它

public function __construct()
{
   echo $this->foo; // displays empty string
   echo Request::$current->foo; // trying to get property of non-object
}

public static function factory()
{
   if(! Request::$initial)
   {
      // constructor is called as part of this line
      $request = Request::$initial = Request::$current = new Request();

      // foo is set AFTER the constructor is called
      $request->foo = 'bar';
   }
   else
   {
      // constructor is called as part of this line
      Request::$current = $request = new Request();

      // foo is set AFTER the constructor is called
      $request->foo = 'aaa';
   }
   return Request::$current;
}