powershell 気になったこと

環境

• windows 10
• PowerShell 7.x

valuefrompipelinebypropertyname

System.Management.Automation.ArgumentTypeConverterAttributeでキャスト可能であれば、引数の型に変更してくれる

enum keyCodes {
    vk_A = 0x41
    ...
    ...
}
function func {
    [CmdletBinding()]
    param (
        [Parameter(Position=0, Mandatory, ValueFromPipeline, ValueFromPipelinebyPropertyName)]
        [ValidateNotNullOrEmpty()]
        [int] $code1,

        [Parameter(Position=1, Mandatory, ValueFromPipeline, ValueFromPipelinebyPropertyName)]
        [ValidateNotNullOrEmpty()]
        [string] $code2
    )

    process {
        Write-Output "$code1, $code2"
    }
}

[keyCodes]::vk_A | func

実行結果

65, vk_A

Call演算子

Write-Output後の一回目の値が変わらない
dot演算子、foreach-Objectでは期待通りに動作する

$dateAfterWriteOutput = Get-Date
$dateBeforeWriteOutput = Get-Date
while ($true) {
    1..3 | & {
        process {
            $dateBeforeWriteOutput = Get-Date
            Write-Output "$_ > After : $dateAfterWriteOutput, Before : $dateBeforeWriteOutput"
            Start-Sleep -s 1
            $dateAfterWriteOutput = Get-Date
        }
    }
}

実行結果

1 > After : 07/31/2022 18:21:31, Before : 07/31/2022 18:21:31
2 > After : 07/31/2022 18:21:32, Before : 07/31/2022 18:21:32
3 > After : 07/31/2022 18:21:33, Before : 07/31/2022 18:21:33
1 > After : 07/31/2022 18:21:31, Before : 07/31/2022 18:21:34
2 > After : 07/31/2022 18:21:35, Before : 07/31/2022 18:21:35
3 > After : 07/31/2022 18:21:36, Before : 07/31/2022 18:21:36
1 > After : 07/31/2022 18:21:31, Before : 07/31/2022 18:21:37
2 > After : 07/31/2022 18:21:38, Before : 07/31/2022 18:21:38
3 > After : 07/31/2022 18:21:39, Before : 07/31/2022 18:21:39

beginブロックに書けば期待通りに動作する

while ($true) {
    1..3 | & {
        begin {
            $dateAfterWriteOutput = Get-Date
            $dateBeforeWriteOutput = Get-Date
        }
        process {
            $dateBeforeWriteOutput = Get-Date
            Write-Output "$_ > After : $dateAfterWriteOutput, Before : $dateBeforeWriteOutput"
            Start-Sleep -s 1
            $dateAfterWriteOutput = Get-Date
        }
    }
}