Question

我试图模拟一种数据结构和逻辑来处理延迟的日志写入，但是我遇到了一种奇怪的情况。如果返回的arrayList只是一项，则if ([collections.arrayList]$deferredLog = Get-PxDeferredLogItems) {错误，

Cannot convert the "logged: 07/20/2019 10:56:29" value of type "System.String" to type "System.Collections.ArrayList".

有两个项目就可以了。现在，我知道必须将单个项目的数组强制为数组，因为PS有时由于其自身的优势而过于聪明，但是我认为[collections.arrayList]的Add方法即使在第一个Add上也产生了arrayList。是我完全误解了，还是我的逻辑在其他地方错误？我也尝试过像这样转换函数调用的结果 if ([collections.arrayList]$deferredLog = [collections.arrayList](Get-PxDeferredLogItems)) {，但更糟的是，每次通话都会出错。我还尝试在Main中使用Set-PxDeferredLogItems (New-Object collections.arrayList)将变量初始化为空的arrayList，而不是在第一次调用Add-PxDeferredLogItem时将n初始化为空，但这显示出相同的行为，直到延迟的日志包含两项为止。我通过在错误行之后直接将Write-Host更改为Write-Host "Process deferred items $($deferredLog.count)"来验证这一点，直到出现2之前我都收到了错误，然后一切正常。

function Get-PxDeferredLogItems {
    return $script:deferredLogItems
}
function Set-PxDeferredLogItems {
    param (
        [collections.arrayList]$deferredLog
    )
    [collections.arrayList]$script:deferredLogItems = $deferredLog
}

function Add-PxDeferredLogItem {
    param (
        [string]$item
    )
    if (-not $script:deferredLogItems) {
        [collections.arrayList]$script:deferredLogItems = New-Object collections.arrayList
    }
    [void]$script:deferredLogItems.Add($item)
}

function Add-PxLogContent {
    param (
        [string]$string
    )

    function Assert-PxWrite {
        if ((Get-Random -minimum:1 -maximum:4) -gt 1) {
            return $true
        } else {
            return $false
        }
    }

    if ([collections.arrayList]$deferredLog = Get-PxDeferredLogItems) {
        Write-Host "Process deferred items"
        :deferredItemsWrite do {
            if (Assert-PxWrite) {
                Write-Host "$($deferredLog[0]) ($(Get-Date))"
                $deferredLog.RemoveAt(0)
            } else {
                break :deferredItemsWrite
            }
        } while ($deferredLog.count -gt 0)
        if ($deferredLog.count -eq 0) {
            $deferredLogPending = $false
        } else {
            $deferredLogPending = $true
        }
        Set-PxDeferredLogItems $deferredLog
    } else {
        $deferredLogPending = $false
    }

    if (-not $deferredLogPending) {
        if (Assert-PxWrite) {
            Write-Host $string
        } else {
            Add-PxDeferredLogItem $string
        }
    } else {
        Add-PxDeferredLogItem $string
    }
}


### MAIN 
$startTime = Get-Date
$endTime = $startTime + (New-TimeSpan -minutes:2)
Clear-Host

do {
    Add-PxLogContent "logged: $(Get-Date)"
    Start-SLeep -s:5
} while ((Get-Date) -lt $endTime) 

if ($deferredLog = Get-PxDeferredLogItems) {
    foreach ($item in $deferredLog) {
        Write-Host "!$item"
    }
}

编辑：这似乎与传递arrayList有关，因为在不涉及任何函数的情况下，此操作可以按预期工作。

Clear-Host

$deferredLogItems = New-Object collections.arrayList
Write-Host "$($deferredLogItems.getType()) $($deferredLogItems.count) $deferredLogItems"
[void]$deferredLogItems.Add('One')
Write-Host "$($deferredLogItems.getType()) $($deferredLogItems.count) $deferredLogItems"
[void]$deferredLogItems.Add('Two')
Write-Host "$($deferredLogItems.getType()) $($deferredLogItems.count) $deferredLogItems"
[void]$deferredLogItems.Add('Three')
Write-Host "$($deferredLogItems.getType()) $($deferredLogItems.count) $deferredLogItems"


function Get-DeferredLogItems {
    if (-not $script:deferredLogItems) {
        [collections.arrayList]$script:deferredLogItems = New-Object collections.arrayList
    }
    [void]$script:deferredLogItems.Add("$($script:deferredLogItems.count + 1)")
    return $script:deferredLogItems
}

$script:deferredLogItems = $localDeferredLogItems = $null
foreach ($i in 1..5) {
    [collections.arrayList]$localDeferredLogItems = Get-DeferredLogItems
    Write-Host "$($localDeferredLogItems.getType()) $($localDeferredLogItems.count) $localDeferredLogItems"
}

EDIT2：由于混乱，用实际的令人反感的代码行替换了＃行引用。

EDIT3：值得一试的是，将Get-DeferredLogItems的结果强制为数组确实可以工作。但是我仍然想知道为什么甚至需要这样做。为什么Add方法在第一次添加时会产生正确的arrayList，但是当作为返回值传递时，PowerShell会@％＃$加起来。

collections.ArrayList Add方法在第一个Add

0 个答案: