powershell - 在 powershell 脚本中强制立即评估（按值复制变量，而不是引用）

Question

我对以下代码有问题

foreach ($ex in ("foo", "bar", "baz")) {
$timer = New-Object Timers.timer
$taction =  {
    Write-Host "Timer fired for: $ex"
}
$timer.Interval = 1000 
$timer.AutoReset = $false
$timer.Start()

Register-ObjectEvent -InputObject $timer -EventName elapsed -SourceIdentifier "$ex" -Action $taction

}

此代码给出以下输出

Timer fired for: baz
Timer fired for: baz
Timer fired for: baz

但我想要它 foo、bar 和 baz。问题似乎是 $ex 变量最终被所有计时器读取，所以无论它有什么值，他们都得到它。如何在 $taction 中复制 $ex 的值以使其唯一？

Answer 1

尝试使用[scriptblock]::Create()，这会在创建时评估参数：

foreach ($ex in ("foo", "bar", "baz"))
{

$timer = New-Object Timers.timer
$taction =  [scriptblock]::create("Write-Host Timer fired for: $ex")

$timer.Interval = 1000 
$timer.AutoReset = $false
$timer.Start()

Register-ObjectEvent -InputObject $timer -EventName elapsed -SourceIdentifier $ex  -Action $taction
}