从新对象中删除引用“&”会导致 PHP 中出现意外问题

Question

我正在维护一些遗留代码，并且一直在删除对新对象的引用，例如：

$object = & new SomeObject();

对此：

$object = new SomeObject();

而且，尽管事实上它不应该有任何区别，因为 PHP5 确实搞砸了一些非常糟糕的事情，因为对象根本不再是引用。如果 & 被替换在那里，问题就会消失。

这是一个示例代码：

<?php

class TreeNode
{
    public $subtree;
    public $name;
    public $layer;
    public $children;

    function &addNode(&$node)
    {
        $this->children[] = &$node;
    }

}

$subtree = array(array('bla','blubb'), 'foo');

$tree = new TreeNode();
$tree->subtree = $subtree;
$tree->layer = 0;
$tree->name = 'root';

$b = buildTree($tree);

print_r($b);

function &buildTree(&$tree) {
    if(is_array($tree->subtree))
    {
        foreach($tree->subtree as $key => $subtree)
        {
            $node = new TreeNode(); ///#### This line is a toggle and it's unknown why
            $node->layer = $tree->layer + 1;
            $node->subtree = $subtree;
            $tree->addNode( buildTree($node) );
            unset($tree->subtree[$key]);
        }
    }
    else
    {
        $tree->name = $tree->subtree;
    }

    return $tree;
}

?>

如果行是$node = new TreeNode();，输出是：树节点对象 ( [subtree] => 数组 ( )

    [name] => root
    [layer] => 0
    [children] => Array
        (
            [0] => TreeNode Object
                (
                    [subtree] => foo
                    [name] => foo
                    [layer] => 1
                    [children] => 
                )

            [1] => TreeNode Object
                (
                    [subtree] => foo
                    [name] => foo
                    [layer] => 1
                    [children] => 
                )

        )

)

如果行是 $node = & new TreeNode(); 输出是：树节点对象 ( [subtree] => 数组 ( )

    [name] => root
    [layer] => 0
    [children] => Array
        (
            [0] => TreeNode Object
                (
                    [subtree] => Array
                        (
                        )

                    [name] => 
                    [layer] => 1
                    [children] => Array
                        (
                            [0] => TreeNode Object
                                (
                                    [subtree] => bla
                                    [name] => bla
                                    [layer] => 2
                                    [children] => 
                                )

                            [1] => TreeNode Object
                                (
                                    [subtree] => blubb
                                    [name] => blubb
                                    [layer] => 2
                                    [children] => 
                                )

                        )

                )

            [1] => TreeNode Object
                (
                    [subtree] => foo
                    [name] => foo
                    [layer] => 1
                    [children] => 
                )

        )

)

Answer 1

原来是引用多了导致的问题。有问题的代码看起来像这样：

function &recursiveFunction(&$someobject) {
  $object = & new SomeObject();
  $someobject->recursiveFunction($object);
  return $someobject;
}

从函数中删除引用并在使用该对象的所有地方最终解决了问题，而不必在创建时也有引用。所以这只是参考本身的部分问题，但其他参考也是如此。

function recursiveFunction($someobject) {
  $object = new SomeObject();
  $someobject->recursiveFunction($object);
  return $someobject;
}

我仍然有点不确定为什么会发生这种情况，但这可能是 PHP 内部处理的一些问题 &$object 仍然不同于 $object 即使在较新的版本中也是如此对象应该始终是对象本身的引用。

从新对象中删除引用“&”会导致 PHP 中出现意外问题

Removing reference "&" from new Object causes unexpected issues in PHP

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