php - 无法向 IteratorAggregate 写入新元素？

Question

我认为 IteratorAggregate 仅提供对对象的类数组读取 访问是否正确？如果我需要写入对象数组，那么我需要使用 Iterator 吗？

尝试添加新元素时 IteratorAggregate 对象导致 fatal error 的演示如下:

<?

class foo implements IteratorAggregate {

    public $_array = array('foo'=>'bar', 'baz'=>'quux');

    public function getIterator() {
        return new ArrayIterator($this->_array);
    }

} // end class declaration


$objFoo = & new foo();

foreach ( $objFoo as $key => $value ) {
        echo "key: $key, value: $value\n";
}

$objFoo['reeb'] = "roob";

foreach ( $objFoo as $key => $value ) {
        echo "key: $key, value: $value\n";
}

---

$ php test.php
key: foo, value: bar
key: baz, value: quux

Fatal error: Cannot use object of type foo as array in /var/www/test.php on line 20

Call Stack:
    0.0009      57956   1. {main}() /var/www/test.php:0

Answer 1

对于它的值(value)，给定您的示例类，您可以使用 ArrayObject(它实现了 IteratorAggregate 和 ArrayAccess，例如我们想要)。

class Foo extends ArrayObject
{
    public function __construct()
    {
        parent::__construct(array('foo' => 'bar', 'baz' => 'quux'));
    }
}

$objFoo = new Foo();

foreach ( $objFoo as $key => $value ) {
    echo "$key => $value\n";
}

echo PHP_EOL;

$objFoo['foo'] = 'badger';
$objFoo['baz'] = 'badger';
$objFoo['bar'] = 'badger';

foreach ( $objFoo as $key => $value ) {
    echo "$key => $value\n";
}

输出如预期的那样:

foo => bar
baz => quux

foo => badger
baz => badger
bar => badger