當(dāng)你調(diào)用某個函數(shù)時，PowerShell會增加一次嵌套層次。當(dāng)一個函數(shù)調(diào)用了另一個函數(shù)，或著腳本，也會增加嵌套層次。今天分享一個函數(shù)，它能告訴你的腳本嵌套的層次：

function Test-NestLevel{$i = 1$ok = $truedo{try{$test = Get-Variable -Name Host -Scope $i}catch{$ok = $false}$i++} While ($ok) $i}

當(dāng)你調(diào)用的函數(shù)具有遞歸調(diào)用時，上面的函數(shù)非常有用，來看一個調(diào)用的示例:

function Test-Diving{param($Depth) if ($Depth -gt 10) { return } "Diving deeper to $Depth meters..." $currentDepth = Test-NestLevel"calculated depth: $currentDepth" Test-Diving -depth ($Depth+1)} Test-Diving -depth 1 

當(dāng)你運行Test-Diving時，函數(shù)會調(diào)用自己10次。函數(shù)使用一個參數(shù)來控制嵌套層次，而Test-NestLevel負(fù)責(zé)返回確切的深度數(shù)。

注意這里有個區(qū)別：Test-NestLevel返回絕對的嵌套層次，參數(shù)會紀(jì)錄這個函數(shù)調(diào)用自己多少次。如果Test-Diving被嵌入到另外一個函數(shù)中，絕對深度和相對深度會不同。

PS C:/> Test-Diving -Depth 1diving deeper to 1 meters...calculated depth: 1diving deeper to 2 meters...calculated depth: 2diving deeper to 3 meters...calculated depth: 3diving deeper to 4 meters...calculated depth: 4diving deeper to 5 meters...calculated depth: 5diving deeper to 6 meters...calculated depth: 6diving deeper to 7 meters...calculated depth: 7diving deeper to 8 meters...calculated depth: 8diving deeper to 9 meters...calculated depth: 9diving deeper to 10 meters...calculated depth: 10 PS C:/> & { Test-Diving -Depth 1 }diving deeper to 1 meters...calculated depth: 2diving deeper to 2 meters...calculated depth: 3diving deeper to 3 meters...calculated depth: 4diving deeper to 4 meters...calculated depth: 5diving deeper to 5 meters...calculated depth: 6diving deeper to 6 meters...calculated depth: 7diving deeper to 7 meters...calculated depth: 8diving deeper to 8 meters...calculated depth: 9diving deeper to 9 meters...calculated depth: 10diving deeper to 10 meters...calculated depth: 11 PS C:/>

Test-NestLevel總會返回從當(dāng)前代碼的作用域到全局作用域的嵌套深度。