php - 在 PHP 中使用工厂模式创建对象

Question

我是 PHP 编程新手，正在尝试做一个基本的工厂模式。我正在尝试使用方法和构造函数创建一个类实例。

$ abstract class Car {
   public $type;
   public function getType(){
   echo $this->type;
   }
  }

 //Class that holds all the details on how to make a Honda.
 class Honda extends Car{
      public  $type = "Honda";
   }

 class CarFactory {
    const HONDA = "Honda";
    public  function __construct($carType){
    switch($carType){
        case self::HONDA:
            return new Honda();
            break;
    }
    die("Car isn't recognized.");
    }

 }

 $Honda = new CarFactory(carFactory::HONDA);
 var_dump($Honda);

结果是 CarFactory 类的对象。为什么它不创建本田类型的对象，因为返回类型是本田类型的对象？是因为我使用的是构造函数吗？

但是，如果我在 CarFactory 中使用如下方法，它会创建一个 Honda 类型的对象

    class CarFactory {
    const HONDA = "Honda";
      public static function createCar($carType){
        switch($carType){
            case self::HONDA:
             return new Honda();
            break;
    }
    die("Car isn't recognized.");
  }
    $carFactory = new CarFactory();
    //Create a Car
    $Honda = $carFactory->createCar(CarFactory::HONDA);
    var_dump($Honda); 

}

提前致谢。
SV

Answer 1

 abstract class Car {
   public static function createCar(){
        try
        { 
          // PHP 5.3+ support
          return new static;
        } 
        catch (Exception $e)
        {
           // in case child does not exists
        }
   }
} 

class Honda extends Car { 

}

$honda = Honda::createCar();
var_dump($honda);