如何将脚本块作为启动作业中的参数之一传递 [英] How do I pass a scriptblock as one of the parameters in start-job

问题描述

我正在尝试创建一个执行脚本块的后台作业.我需要将此脚本块作为参数传递，但我似乎无法使语法起作用.脚本块正在沿途的某个地方转换为字符串.

I'm trying to create a background job, which executes a scriptblock. I need to pass this scriptblock in as a parameter, but I can't seem to get the syntax to work. The scriptblock is being converted to a string somewhere along the way.

当我将脚本块传递给本地函数时它工作正常，但不能通过 start-job

It works fine when I pass the script block to a local function, but not through start-job

以下语法有效:

function LocalFunction
{
    param (
        [parameter(Mandatory=$true)]
        [ScriptBlock]$ScriptBlock
    )

    &$ScriptBlock | % { echo "got $_" }
}

LocalFunction -ScriptBlock { echo "hello" }

这会按预期输出got hello".

This outputs "got hello" as expected.

但以下失败:

$job = start-job -argumentlist { echo "hello" } -scriptblock {
    param (
        [parameter(Mandatory=$true)]
        [ScriptBlock]$ScriptBlock
    )
    &$ScriptBlock | % { echo "got $_" }
}
start-sleep -s 1
receive-job $job

返回的错误是

Receive-Job : Cannot process argument transformation on parameter 'ScriptBlock'. Cannot convert the " echo "hello" " value of type "System.String" to type "System.Management.Automation.ScriptBlock".

因此，如果我正确地阅读了错误，似乎 -argumentlist 以某种方式将其参数强制转换为字符串.

So if I'm reading the error right, it appears that -argumentlist is somehow forcing its arguments into strings.

任何 powershell 专家都知道如何使这种语法起作用?

Any powershell gurus know how to make this syntax work?

提前致谢，

本

推荐答案

这里有一个方法可以解决这个问题，将脚本块代码作为字符串传递，然后从作业内部的字符串创建一个脚本块并执行

Here's one way to solve this, pass the scriptblock code as a string, then create a scriptblock from the string inside the job and execute it

Start-Job -ArgumentList "write-host hello"  -scriptblock {

    param (
        [parameter(Mandatory=$true)][string]$ScriptBlock
    )

    & ([scriptblock]::Create($ScriptBlock))

} | Wait-Job | Receive-Job

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