If your class implements also ArrayAccess interface, you could use as valid() body
function valid(){
return $this->offsetExists($this->position);
}
(PHP 5, PHP 7)
Iterator::valid — 检查当前位置是否有效
此方法在 Iterator::rewind() 和 Iterator::next() 方法之后被调用以此用来检查当前位置是否有效。
此函数没有参数。
返回将被转换为布尔型。成功时返回 TRUE， 或者在失败时返回 FALSE。
If your class implements also ArrayAccess interface, you could use as valid() body
function valid(){
return $this->offsetExists($this->position);
}
If Iterator::valid() returns false, the foreach() loop will be terminated.