ArrayList在函式中首次參考時不顯示

在 PowerShell 中面臨幾個后勤問題 - 顯然我缺少一個基本概念：

設定：創建 menu.ps1 檔案（如下所示），啟動 PowerShell 7.2.2 并在本地呼叫該檔案。

問題：

1. 第一次為 ArrayList ( ) 選擇選項 1 時$psArrayList，它不會顯示（盡管我們從初始螢屏加載中看到專案已填充）。如果您回傳選單并再次選擇選項 1，它將在第二遍時顯示。（$psArray第一次嘗試加載正常，所以這是型別問題。？）
2. 當腳本結束時，$psArrayList并且$psArray仍在當前會話變數中，如：Get-Variable psArray*。即使我用它們實體化它們$script:psArrayList = [System.Collections.ArrayList]@()并且$script:psArray = @()它們似乎仍然在會話范圍內。當 ps1 結束時，是否有“正確”的方法來清除它們？

menu.ps1 內容：

$psArrayList = [System.Collections.ArrayList]@()
# example of populating later in function etc...
$psArrayList.Add([pscustomobject]@{name="bird";color="blue"})
$psArrayList.Add([pscustomobject]@{name="cat";color="orange"})
$psArrayList.Add([pscustomobject]@{name="bear";color="brown"})

$psArray = @()
# example of populating later in function etc...
$psArray  = "dog"
$psArray  = "fish"
$psArray  = "squirrel"

function End-Script {
    Remove-Variable psArray*
    Exit
}
    
function Display-Menu { 
    [int]$choice=-1

    Write-Host "This is a menu..." -ForegroundColor Green

    Write-Host "Here are your options:"
    Write-Host
    Write-Host "`t1 - ArrayList"
    Write-Host "`t2 - Array"
    Write-Host "`t0 - quit (do nothing)"
    Write-Host

    while ($choice -lt 0) { $choice= Read-Host -Prompt "Choose 1-2 (or 0 to quit)" }
    
    Process-Menu($choice)
}

function Process-Menu([int]$choice) {   
    switch($choice) {
        1 { Write-Host "You chose ArrayList:"; Write-Output $psArrayList }
        2 { Write-Host "You chose Array:"; Write-Output $psArray }
        0 { Write-Host "You chose to quit. Exiting."; End-Script }  
    }
    
    $yn=""
    while ($yn -eq "") { $yn= Read-Host -Prompt "Return to main menu? (y/n)" }
    
    if ($yn -eq "y") { Display-Menu } else { Write-Host "Ending..."; End-Script }
}

Display-Menu

uj5u.com熱心網友回復：

關于第一個問題，您需要使用Out-HostorOut-Default以便將兩個輸出（Write-Host連同陣列）正確顯示到控制臺。有關詳細資訊，請參閱這些有用的答案：

• https://stackoverflow.com/a/50416448/15339544
• https://stackoverflow.com/a/34858911/15339544

關于第二個問題，您的End-Script函式將有一個范圍問題，Remove-Variable正在嘗試洗掉在函式范圍內定義的變數（Local），如果您想定位在它之外定義的變數（Script），您需要使用-Scope引數，因為例子：

function End-Script {
    Get-Variable psArray* | Remove-Variable -Scope Script
    # `Remove-Variable psArray* -Scope Script` would be valid too
}

從 cmdlet 的引數部分，我們可以讀取引數的以下內容-Scope：

一個相對于當前作用域的數字（0 到作用域的數量，其中 0 是當前作用域，1 是其父作用域）

從這個意義上說，-Scope 1也可以。

您可以在下面看到一個帶有一些改進和輸入驗證的腳本示例：

$psArrayList = [System.Collections.ArrayList]@()
$psArrayList.AddRange(@(
    [pscustomobject]@{name="bird";color="blue"}
    [pscustomobject]@{name="cat";color="orange"}
    [pscustomobject]@{name="bear";color="brown"}
))

$psArray = "dog", "fish", "squirrel"

function End-Script {
    Get-Variable psArray* | Remove-Variable -Scope Script
}

function Display-Menu {
    Write-Host "This is a menu..." -ForegroundColor Green
    Write-Host "Here are your options:"
    Write-Host
    Write-Host "`t1 - ArrayList"
    Write-Host "`t2 - Array"
    Write-Host "`t0 - quit (do nothing)"
    Write-Host

    # one of many methods for input validation is a Recursive Script Block:
    $tryInput = {
        try {
            [ValidateSet(0, 1, 2)] $choice = Read-Host "Choose 1-2 (or 0 to quit)"
            $choice
        }
        catch {
            Write-Warning 'Invalid choice!'
            & $tryInput
        }
    }
    Process-Menu (& $tryInput)
}

function Process-Menu([int] $choice) {
    switch($choice) {
        1 {
            Write-Host "You chose ArrayList:"
            $psArrayList | Out-Host
        }
        2 {
            Write-Host "You chose Array:"
            $psArray | Out-Host
        }
        0 {
            Write-Host "You chose to quit. Exiting."
            End-Script
            Return # => Exit this function
        }
    }

    $tryInput = {
        try {
            [ValidateSet('y', 'n')] $choice = Read-Host "Return to main menu? (y/n)"
            $choice
        }
        catch {
            Write-Warning 'Invalid choice!'
            & $tryInput
        }
    }

    # No need to check for `N`
    if((& $tryInput) -eq 'y') { Display-Menu }
}

Display-Menu

標籤：电源外壳

上一篇：結構搜索log.debug(String.format....沒有按預期作業

下一篇：“中斷”導致PowerShell腳本失敗