使用开始，过程，结束在脚本块

Question

是否有可能使用adavanced函数的特征是在脚本块Begin, Process, End？

例如我有以下脚本块：

$startStopService = { 
Param(
    [bool] $startService)  

    if ($startService){ 
    ... 
    Start-Service "My-Service" 
    } 
    else { 
    Stop-Service "My-Service" 
    } 
} 

因为我希望能够控制脚本块的详细输出我想块更改为：

$startStopService = { 
Param(
    [bool] $startService)  

    Begin { 
    $oldPreference = $VerbosePreference 
    $VerbosePreference = $Using:VerbosePreference 
    } 
    Process { 
    if ($startService){ 
     ... 
     Start-Service "My-Service" 
    } 
    else { 
     Stop-Service "My-Service" 
    } 
    } 
    End { 
    # Restore the old preference 
    $VerbosePreference = $oldPreference 
    } 
} 

这里有没有可能使用Begin, Process, End，尽管scriptblock不是一个cmdlet？我只是希望VerbosePreference恢复到旧值，无论是否发生错误。当然，我可以使用try{}finally{}作为替代，但我发现Begin, Process, End更直观。

THX

Answer 1

这是可能的，如在about_script_blocks描述：

一样的功能，脚本块可以包括DynamicParam，开始， 过程和结束关键字。欲了解更多信息，请参阅about_Functions 和about_Functions_Advanced。

---

为了验证这一点，我修改你的脚本块，并运行此：

$startStopService = { 
Param(
    # a bool needs $true or $false passed AFAIK 
    # A switch is $true if specified, $false if not included 
    [switch] $startService 
)  

    Begin { 
    $oldPreference = $VerbosePreference 
    Write-Output "Setting VerbosePreference to Continue" 

    # $Using:VerbosePreference gave me an error 
    $VerbosePreference = "Continue" 
    } 
    Process { 
    if ($startService){ 
     Write-Verbose "Service was started" 
    } 
    else { 
     Write-Verbose "Service was not started" 
    } 
    } 
    End { 
    # Restore the old preference 
    Write-Output "Setting VerbosePreference back to $oldPreference" 
    $VerbosePreference = $oldPreference 
    } 

} 

Write-Verbose "This message will not print if VerbosePreference is the default SilentlyContinue" 

. $startStopService -startService 

Write-Verbose "This message will not print if VerbosePreference is the default SilentlyContinue" 

---

后，哪些功能是你吗？如果运行一个脚本块，但在脚本的其余部分没有改变$VerbosePreference时，你会打印详细消息，请考虑使用[CmdletBinding()]和-Verbose标志：

$startStopService = { 
    [CmdLetBinding()] 
    Param(
     [switch] $startService 
    ) 

    Write-Verbose "This is a verbose message" 

} 
Write-Verbose "This message will not print if VerbosePreference is the default SilentlyContinue" 

. $startStopService -verbose 

Write-Verbose "This message will not print if VerbosePreference is the default SilentlyContinue" 

---

编辑 - 调用命令

您的评论后，我寻找到的Invoke-Command功能。并发现很多不起作用的东西。

短的版本，我认为这是最适合您：你可以宣布一个脚本块内$VerbosePreference = "Continue"，这将限制在脚本块的范围。之后无需改变。

$startStopService = { 
    [CmdLetBinding()] 
    Param(
     [parameter(Position=0)] 
     [switch]$startStopService, 

     [parameter(Position=1)] 
     [switch]$Verbose 
    ) 

    if($Verbose){ 
     $VerbosePreference = "Continue" 
    } 

    Write-Verbose "This is a verbose message" 

} 

Write-output "VerbosePreference: $VerbosePreference" 
Write-Verbose "This message will not print if VerbosePreference is the default SilentlyContinue" 

Invoke-Command -Scriptblock $startStopService -ArgumentList ($true,$true) 

Write-output "VerbosePreference: $VerbosePreference" 
Write-Verbose "This message will not print if VerbosePreference is the default SilentlyContinue" 

试图通过-Verbose开关CommonParameter到Invoke-Command是一个没有去。这使用标准Verbose开关参数，允许你传递$true/$false（或省略）来控制详细的输出。

_{相关：
about_Functions
about_Functions_Advanced}