dongsu1539 2015-07-26 12:44
浏览 30
已采纳

从对象迭代数组

I want to perform some magic so that when I try to iterate over an object I will actually iterate over an array from within the object. Something like a getter for loops.

class A {
    protected $array = [1,2,3];

    public function __foriteration() {
        return $this->array;
    }
}

$a = new A;

foreach($a as $value) {
   echo $value;
}

// output should be "123"

Not even sure that this is possible but I suspect I should be using ArrayObject but it is not very straightforward for me, I can't figure out how to make it do this.

Please note: I could define a getter method and loop over $a->getArray() but that is not what I want to do. Thank you.

  • 写回答

2条回答 默认 最新

  • duanren9163 2015-07-26 12:52
    关注

    You can implement the Iterator interface. To do that, you need to implement a couple of methods in your object, which you can redirect to your array:

    <?php
    
    class A implements Iterator {
        protected $array = [1,2,3];
    
        public function __foriteration() {
            return $this->array;
        }
    
        public function rewind()
        {
            reset($this->array);
        }
    
        public function current()
        {
            $value = current($this->array);
            return $value;
        }
    
        public function key() 
        {
            $key = key($this->array);
            return $key;
        }
    
        public function next() 
        {
            $value = next($this->array);
            return $value;
        }
    
        public function valid()
        {
            $key = key($this->array);
            return $key !== null && $key !== false;
        }    
    }
    
    $a = new A;
    
    foreach($a as $value) {
       echo $value;
    }
    

    Of course you can implement your own method of keeping track of the 'current' item, but since an array does that already, it's as easy to let it do it for you, and methods like rewind just call array functions.

    本回答被题主选为最佳回答 , 对您是否有帮助呢?
    评论
查看更多回答(1条)

报告相同问题?

悬赏问题

  • ¥15 ecplise在连接数据库时显示加载驱动成功但是数据库连接失败
  • ¥15 visionmaster启动失败,提示为“机器不满足授权而被禁用”
  • ¥50 用logisim设计16位单时钟周期cpu
  • ¥15 IDEA中圈复杂度如何具体设置
  • ¥50 labview采集不了数据
  • ¥15 Multisim红外倒车雷达仿真中距离问题
  • ¥15 请上面代码做什么处理或什么混淆
  • ¥15 英雄联盟自定义房间置顶
  • ¥15 W5500网线插上无反应
  • ¥15 如何用字典的Key,显示在WPF的xaml中