$helloWorld = function() {
    return 'hello world';
};

var_dump($helloWorld);

/*
返回结果如下：
object(Closure)#1 (0) {
}
*/
Copy

// 闭包类
class Closure{
    // 禁止实例化
    private __construct()
    {

    }

    // 复制一个闭包,绑定指定的 $newThis 对象和类的作用域
    public static function bind(Closure $closure, object $newThis, mixed $newscope = 'static') :Closure
    {
        // TO-DO
    }

    // 复制当前闭包对象, 绑定指定的 $newThis 对象和类的作用域 
    public function bindTo(object $newThis, mixed $newscope = 'static') :Closure
    {
        // TO-DO
    }

    // 魔术方法,无作用
    public function __invoke()
    {
        // TO-DO
    }
}
Copy

$params = ['10', '20', '30', '40'];

$newArray = array_map(function($item) {
    return intval($item);
}, $params);

var_dump($newArray);

/*
返回结果如下：
array(4) {
  [0]=>
  int(10)
  [1]=>
  int(20)
  [2]=>
  int(30)
  [3]=>
  int(40)
}

*/Copy

/**
 * Closure class a method
 * 复制一个闭包,绑定指定的 $newThis对象和类的作用域
 *
 * @param Closure $closure
 * @param object $newThis
 * @param mixed $newscope
 * @return \Closure
 */
public static function bind(Closure $closure, object $newThis, mixed $newscope = 'static') :Closure
{
    // TO-DO
}Copy

class Order
{
    private $orderId = '001';

    private static $defaultMoney = '100';

    public $num = 1;
}

$getOrderId = function() {
    return $this->orderId;
};

$getNum = function() {
    return $this->num;
};

$getDefaultMoney = static function() {
    return Order::$defaultMoney;
};
Copy

$getDefaultMoney1 = Closure::bind($getDefaultMoney, null, Order::class);
// 输出：100

$getOrderId1 = Closure::bind($getOrderId, null, Order::class);
// 输出:PHP Fatal error:  Uncaught Error: Using $this when not in object context

$getNum1 = Closure::bind($getNum, null, Order::class);
// 输出:PHP Fatal error:  Uncaught Error: Using $this when not in object contextCopy

$getDefaultMoney2 = Closure::bind($getDefaultMoney, new Order(), Order::class);
// 输出：PHP Warning:  Cannot bind an instance to a static closure

$getOrderId2 = Closure::bind($getOrderId, new Order(), Order::class);
// 输出 string(3) "001"

$getNum2 = Closure::bind($getNum, new Order(), Order::class);
// 输出 int(1)Copy

$getDefaultMoney3 = Closure::bind($getDefaultMoney, new Order());
// 输出 PHP Warning:  Cannot bind an instance to a static closure

$getOrderId3 = Closure::bind($getOrderId, new Order());
// 输出 Fatal error: Uncaught Error: Cannot access private property Order::$orderId

$getNum3 = Closure::bind($getNum, new Order());
// 输出 int(1)Copy

$getOrderId1 = $getOrderId->bindTo(new Order(), Order::class);Copy

$order = new Order();
echo $order->getOrderId();

// 代码段
function getOrderId()
{
    return $this->orderId;
}Copy