Php 扩展的DomeElement对象将丢失它'；导入到另一个文档中时的属性

当将具有特定属性的扩展DomeElement对象导入到另一个DOMDocument中时，所有属性都会丢失（我猜它实际上并没有复制no，而是为另一个文档创建了一个新节点，并且只将DomeElement类的值复制到新节点）。让属性在导入的元素中仍然可用的最佳方法是什么

下面是一个问题示例：

<?php

class DOMExtendedElement extends DOMElement {

    private $itsVerySpecialProperty;

    public function setVerySpecialProperty($property) {$this->itsVerySpecialProperty = $property;}

}

// First document

$firstDocument = new DOMDocument();

$firstDocument->registerNodeClass("DOMElement", "DOMExtendedElement");

$elm = $firstDocument->createElement("elm");
$elm->setVerySpecialProperty("Hello World!");

var_dump($elm);

// Second document

$secondDocument = new DOMDocument();

var_dump($secondDocument->importNode($elm, true)); // The imported element is a DOMElement and doesn't have any other properties at all

// Third document

$thirdDocument = new DOMDocument();

$thirdDocument->registerNodeClass("DOMElement", "DOMExtendedElement");

var_dump($thirdDocument->importNode($elm, true)); // The imported element is a DOMExtendedElement and does have the extra property but it's empty


?>

---

它可能有更好的解决方案，但您可能需要克隆第一个对象

class DOMExtendedElement extends DOMElement {

    private $itsVerySpecialProperty;

    public function setVerySpecialProperty($property) {$this->itsVerySpecialProperty = $property;}
    public function getVerySpecialProperty(){ return isset($this->itsVerySpecialProperty) ?: ''; }
}
// First document
$firstDocument = new DOMDocument();
$firstDocument->registerNodeClass("DOMElement", "DOMExtendedElement");
$elm = $firstDocument->createElement("elm");
$elm->setVerySpecialProperty("Hello World!");
var_dump($elm);

$elm2 = clone $elm;
// Third document
$thirdDocument = new DOMDocument();
$thirdDocument->registerNodeClass("DOMElement", "DOMExtendedElement");
$thirdDocument->importNode($elm2); 
var_dump($elm2);

结果:

object(DOMExtendedElement)#2 (1) {
  ["itsVerySpecialProperty:private"]=>
  string(12) "Hello World!"
}
object(DOMExtendedElement)#3 (1) {
  ["itsVerySpecialProperty:private"]=>
  string(12) "Hello World!"
}

在您的示例中，最后一行的var_dump实际上并没有输出导入的元素，而是$firstDocument的克隆元素。它应该是：var_dump（$thirdDocument->importNode（$elm，true））；你终究会看到那处房产还是没了你的最终目标是什么？保存XML？