我马上就知道你们中的一些人会假设接口(interface)或抽象，但这只能处理某些情况。这是它们损坏的示例。

假设我们有实现相同接口(interface)并扩展相同基类的类

  class car extends fourwheeler implements ipaygas{       

    protected $tank1;

    //interface
    public function payGas($amount){}

  }

  class sportscar extends fourwheeler implements ipaygas{

    protected $tank1;
    protected $tank2;

    //interface
    public function payGas($amount){}

  }

  interface ipaygas{

    function payGas($amount);
  }

在某些情况下，您只需要一个接口(interface)即可，因为您可能只想执行“payGas()”。但是当你有条件要满足时你会怎么做。

例如，如果 - 在支付汽油费之前，您需要 (1) 检查车型，(2) 为跑车使用高级汽油，以及 (3) 为跑车的第二个油箱加满油。

这是我想做却做不到的

   function pumpAndPay(iPayGas $car){
     if(gettype($car) == "car"){
       fillTank($car,(car) $car->tank1);
     }else{
       fillTank($car,(sportscar) $car->tank1);
       fillTank($car,(sportscar) $car->tank2);
     }
   }

如何使用真实类型转换来做到这一点？在 PHP 中可以吗？

更新(基于回复): 在我的“真实”案例中……假设我必须检查各种车辆类型，每种车辆都有不同的油漆、车身、内饰、gas_type、cleaner_type、颜色等……

   abstract class AVechicle{}
   abstract class ACar extends AVechicle{}
   abstract class ATruckOrSUV extends AVechicle{}
   abstract class ABike extends AVechicle{}

   class Car extends ACar{}
   class SportsCar extends ACar{}
   class SUV extends ATruckOrSUV{}
   class Truck extends ATruckOrSUV{}
   class Bike extends ABike{}
   class Scooter extends ABike{}

   class GasStation{

     public function cleanVehicle(AVehicle $car){
       //assume we need to check the car type to know
       //what type of cleaner to use and how to clean the car
       //if the car has leather or bucket seats

       //imagine we have to add an extra $2/h for sports cars

       //imagine a truck needs special treatment tires
       //or needs inspection
     }

     public function pumpAndPay(AVehicle $car){
       //need to know vehicle type to get gas type

       //maybe we have a special for scooters only, Green Air campaign etc.
     }

     public function fullService(AVehicle $car){
       //need to know if its a truck to do inspection FIRST

       $this->cleanVehicle($car);
       $this->pumpAndPay($car);

       //bikes get 10% off
       //cars get free carwash
     }

   }

仅靠接口(interface)和抽象就够了……

最佳答案

对你的问题的简短回答，不，你不能将一个对象重新转换为另一个对象。

不过，Dan Lee 的回应很好，接近我的建议。为什么不让 fillTank 成为车辆对象的属性，这样所有扩展车辆类的对象都知道如何填充自己的油箱。像这样:

abstract class Vehicle
{
    protected $tank1;
    protected $tank2;

    // Declaring an abstract function in parent class forces all child class to 
    // implement same class
    abstract public function fillGas() {}
}

class Car extends Vehicle
{
    public function fillGas()
    {
        $this->tank1 = 'full';
    }
}

class SportsCar extends Vehicle
{
    public function fillGas()
    {
        $this->tank1 = 'full';
        $this->tank2 = 'full';
    }
}

class Skateboard extends Vehicle
{
    // Skateboards don't have gastanks, just here to sastify parent abstract definition
    public function fillGas() {}
}

当然，您的 OP 的最大谬误是您假设所有跑车都有两个油箱，而实际上并非如此。只有某些跑车有多个油箱。

另一种方法是查看traits ( available as of PHP 5.4 )。看来您可以在不扩展同一类的对象之间强制执行接口(interface)和实现。

-- 更新--

Update (Based on responses): In my 'real' case... imagine I have to check various Vehicle types, each with different paint, body, interior, gas_type, cleaner_type, color, etc...

您提到的所有这些属性都是车辆属性，而不是 gastation、fillingstation、parkinglot 等属性，因此我会将所有这些属性添加到车辆类中，然后您可以将车辆传递给 GasStation::cleanVehicle( ) 操纵车辆属性的工厂方法。

下面的代码片段只是DEMONSTRATIVE，展示了如何将上述属性附加到车辆类，以及 GasStation 类如何根据类操作车辆属性的车辆。我在 5 分钟内写了以下内容，但很明显，正确处理工厂方法以及是否传递给其他对象等需要更多考虑。考虑以下几点:

abstract class Vehicle
{
    // Setting these to public for demonstration only, otherwise you should set these 
    //  to protected and write public accessors 
    public $paintType;
    public $bodyType;
    public $interior;
}

class Car extends Vehicle
{
}

class Suv extends Vehicle
{
}

class Truck extends Vehicle
{
}

class GasStation
{
    public static function cleanVehicle(Vehicle $vehicle)
    {
        switch (get_class($vehicle)) {

            case 'Car':
                // Car specific cleaning
                break;

            case 'Truck':
                // Truck specific cleaning
                break;

            default:
                throw new Exception(sprintf('Invalid $vehicle: %s', serialize($vehicle)));
        }

        // We've gone through our vehicle specific cleaning, now we can do generic
        if ('Leather' === $vehicle->getInterior()) {
            // Leather specific cleaning
        }

        if ('Sedan' === $vehicle->getBodyType()) {
            // Sedan specific cleaning
        }
    }
 }

$car = new Car();

$car->setPaintType = 'Glossy';
$car->setBodyType = 'Sedan';
$car->setInterior = 'Cloth';

$suv = new Suv();

$suv->setPaintType = 'Glossy';
$suv->setBodyType = 'Crossover';
$suv->setInterior = 'Leather';

$truck = new Truck();

$truck->setPaintType = 'Flat';
$truck->setBodyType = 'ClubCab';
$truck->setInterior = 'Cloth';

$vehicles = array($car, $suv, $truck);

foreach ($vehicles as $vehicle) {
    GasStation::cleanVehicle($vehicle);
}

关于php - 在 PHP 中转换自定义类的最佳方法是什么，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/10217428/