指定子类中的变量父

Question

类

我有这些相关的类：

class cars { 

    public $cars; 

    public function addCar($name, $car) 
    { 
     $this->cars[$name] = $car; 
    } 

    public function getCars() 
    { 
     return $this->cars; 
    } 

    public function getCar($name) 
    { 
     return $this->cars[$name]; 
    } 

    public function getParams() 
    { 
     return $this->params; 
    } 
} 

$cars = new cars(); 

class bmw extends cars { 

    private static $_instance = null; 
    protected $params; 

    function __construct() 
    { 
     $this->params['param'] = 'foo'; 
    } 

    public static function init() 
    { 
     if (self::$_instance === null) { 
      self::$_instance = new self; 
     } 

     return self::$_instance; 
    } 
} 

$cars->addCar('bmw', bmw::init()); 

基本上我需要从父类访问所有子类。并使用父类中定义的方法定义这些子类。添加新的子类时不应修改父类。

到底这应该是这样的：

foreach($cars->getCars() as $car) 
{ 
    foreach($car->getParams() as $key => $param) 
     echo "$key = $param"; 
} 

什么是做到这一点的正确方法？

Answer 1

提供帮助确实很困难，因为它不太清楚你想要达到的目标。

在我看来，你需要注册表类（carDealer），这是一个抽象类，具有共同的（对于每个孩子）方法和一个孩子（Bmw）。

所以，像这样：

// You seems to need what is called sometimes a Registry. 
// Something which deal with keeping and delivering a group of 'related' classes, as a register. 
class CarsDealer 
{ 
    public $cars; 

    public function addCar($name, $car) 
    { 
     $this->cars[$name] = $car; 
    } 

    public function getCars() 
    { 
     return $this->cars; 
    } 

    public function getCar($name) 
    { 
     return $this->cars[$name]; 
    } 
} 

// then you need a basic contract for each concrete classes 
// that will have the same nature and so will extend it 
abstract class Car 
{ 
    protected $params; 

    public function getParams() 
    { 
     return $this->params; 
    } 
} 

// finally the concrete class 
class Bmw extends Car 
{ 
    public function __construct($params = null) 
    { 
     $this->params['param'] = $params; 
    } 
} 

$carsDealer = new CarsDealer(); 

$carsDealer->addCar('bmw', new Bmw('foo')); 

foreach ($carsDealer->getCars() as $car) 
{ 
    foreach ($car->getParams() as $key => $param) { 
     echo "$key = $param"; 
    } 
} 

请注意一些基本规则/良好做法/惯例：

• 类命名，总是大写
• 责任（一类宝马不该” t有一个方法getCars，至少在本例中不是这样）
• Visibility方法，参数
• http://www.php-fig.org/psr/psr-1/
• http://www.php-fig.org/psr/psr-2/

Answer 2

只是一个另一种方法，如果你只需要得到这个 'PARAMS' :-)

class cars { 

    public $cars; 

    public function addCar($name, $car) 
    { 
     $this->cars[$name] = $car; 
    } 

    public function getCars() 
    { 
     return $this->cars; 
    } 

    public function getCar($name) 
    { 
     return $this->cars[$name]; 
    } 

    public function getParams($obj) 
    { 
     return $obj->params; 
    } 


} 

$cars = new cars(); 

class bmw extends cars { 

    private static $_instance = null; 
    protected $params; 

    function __construct() 
    { 
     $this->params['param'] = 'foo'; 
    } 

    public static function init() 
    { 
     if (self::$_instance === null) { 
      self::$_instance = new self; 
     } 

     return self::$_instance; 
    } 
} 

$cars->addCar('bmw', bmw::init()); 

print_r($cars->getParams($cars->getCar('bmw')));