如何在PowerShell中配置System.Xml.XmlWriter

Question

我正在尝试处置XmlWriter对象:

try
{
    [System.Xml.XmlWriter] $writer = [System.Xml.XmlWriter]::Create('c:\some.xml')
}
finally
{
    $writer.Dispose()
}

错误:

方法调用失败,因为[System.Xml.XmlWellFormedWriter]不包含名为"Dispose"的方法.

另一方面:

 $writer -is [IDisposable]
 # True

我该怎么办？

Answer 1

处置是保护上System.Xml.XmlWriter.你应该使用Close.

$writer.Close

Answer 2

这是另一种方法:

(get-interface $obj ([IDisposable])).Dispose()

Get-Interface脚本可以在http://www.nivot.org/2009/03/28/PowerShell20CTP3ModulesInPracticeClosures.aspx找到,并在此响应中提出.

使用'using'关键字,我们得到:

$MY_DIR = Split-Path -Path $MyInvocation.MyCommand.Definition -Parent

# http://www.nivot.org/2009/03/28/PowerShell20CTP3ModulesInPracticeClosures.aspx
. ($MY_DIR + '\get-interface.ps1')

# A bit modified code from http://blogs.msdn.com/powershell/archive/2009/03/12/reserving-keywords.aspx
function using
{
    param($obj, [scriptblock]$sb)

    try {
        & $sb
    } finally {
        if ($obj -is [IDisposable]) {
            (get-interface $obj ([IDisposable])).Dispose()
        }
    }
}

# Demo
using($writer = [System.Xml.XmlWriter]::Create('c:\some.xml')) {

}