interface Yielder
{
public function getData(): iterable;
}
class ClassicYielder implements Yielder
{
public function getData(): iterable
{
yield 1;
yield 2;
yield 3;
yield 4;
yield 5;
}
}
class LimitedYielder implements Yielder
{
private $wrapped;
private $total = 3;
private $count = 0;
public function __construct(Yielder $wrapped)
{
$this->wrapped = $wrapped;
}
public function getData(): iterable
{
if ($this->count < $this->total) {
$this->count++;
yield from $this->wrapped->getData();
}
// how to stop here?
}
}
$x = new ClassicYielder();
$y = new LimitedYielder($x);
foreach ($y->getData() as $data) {
echo $data;
}
===
Will print: 1 2 3 4 5
我有一个Yielder接口,它具有一个通过yield返回可迭代的单一方法。我想将我的经典yielder包装在一个有限的变量中,只要条件通过,它只会产生值。如您所见,上面的代码将产生我经典的yielder的所有值,而无需跟踪我的计数器。
我在这里做错了什么?有什么办法可以使它正常工作?