PowerShell 5自定义类存入哈希表后更新异常问题求助

我创建了一个PowerShell自定义类变量，并将其存入哈希表的键值对“value”部分。但当我更新该自定义类中的整数字段时，另一个键值对也随之改变。

程序代码 #

class Contact
{
  [ValidateNotNullOrEmpty()][string]$First
  [ValidateNotNullOrEmpty()][string]$Last
  [ValidateNotNullOrEmpty()][int]$Changes
}

$ClassMates=@{}

$C = [Contact]@{
First = "Joel"
Last = "Bennett"
Changes = 0
}
$ClassMates['Child1']=$C

$C.First="Justine"
$C.Last="Smith"
$C.Changes=0
$ClassMates['Child2']=$C

write-host "All Class Mates"
write-host "---------------"
foreach ($child in $ClassMates.Keys) 
{
Write-Host $child ":"
[Contact] $thischild=$($ClassMates.Item($child))
write-host $thischild.First
write-host $thischild.Last
write-host $thischild.Changes
}

$C=$ClassMates['Child2']
$C.First="Justine"
$C.Last="Smythe"
$C.Changes++
$ClassMates['Child2']=$C

write-host "All Class Mates After Update"
write-host "----------------------------"
foreach ($child in $ClassMates.Keys) 
{
Write-Host $child ":"
[Contact] $thischild=$($ClassMates.Item($child))
write-host $thischild.First
write-host $thischild.Last
write-host $thischild.Changes
}

运行输出 #

.\CustomVarTypes2.ps1
All Class Mates
---------------
Child1 :
Justine
Smith
0
Child2 :
Justine
Smith
0
All Class Mates After Update
----------------------------
Child2 :
Justine
Smythe
1
Child1 :
Justine
Smythe
1

可以看到Child1的Changes字段本应保持为0，请问哪里出错了？该如何修复？

PowerShell中的自定义类属于引用类型，当你把$C对象存入哈希表时，哈希表中存储的并不是对象的副本，而是指向该对象在内存中的引用地址。所以Child1和Child2两个键实际上指向的是同一个Contact对象，无论修改哪一个引用指向的对象属性，都会影响到所有指向该对象的键值对。

需要为每个哈希表条目创建独立的Contact实例，避免复用同一个对象引用。有两种常见方式：

方式1：每次添加时创建新实例 #

不用复用$C变量，每次添加到哈希表前都新建一个Contact对象：

$ClassMates=@{}

# 添加Child1
$ClassMates['Child1'] = [Contact]@{
    First = "Joel"
    Last = "Bennett"
    Changes = 0
}

# 添加Child2，创建新实例
$ClassMates['Child2'] = [Contact]@{
    First = "Justine"
    Last = "Smith"
    Changes = 0
}

# 后续更新Child2时，修改的是独立实例
$C = $ClassMates['Child2']
$C.Last = "Smythe"
$C.Changes++
$ClassMates['Child2'] = $C

方式2：复制现有对象的属性到新实例 #

如果需要基于现有对象创建新实例，可以复制原对象的属性到新的Contact实例中：

$ClassMates=@{}

$C = [Contact]@{
    First = "Joel"
    Last = "Bennett"
    Changes = 0
}
$ClassMates['Child1'] = $C

# 复制$C的属性到新实例，再存入Child2
$ClassMates['Child2'] = [Contact]@{
    First = $C.First
    Last = $C.Last
    Changes = $C.Changes
}
# 修改Child2的属性
$ClassMates['Child2'].First = "Justine"
$ClassMates['Child2'].Last = "Smith"

# 后续更新操作只会影响Child2的独立实例
$C = $ClassMates['Child2']
$C.Last = "Smythe"
$C.Changes++
$ClassMates['Child2'] = $C

内容的提问来源于stack exchange，提问作者phillip-from-oz