當你調用某個函數時，PowerShell會增加一次嵌套層次。當一個函數調用了另一個函數，或著腳本，也會增加嵌套層次。今天分享一個函數，它能告訴你的腳本嵌套的層次：
function Test-NestLevel
{
$i = 1
$ok = $true
do
{
try
{
$test = Get-Variable -Name Host -Scope $i
}
catch
{
$ok = $false
}
$i++
} While ($ok)
$i
}
當你調用的函數具有遞歸調用時，上面的函數非常有用，來看一個調用的示例:
function Test-Diving
{
param($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
當你運行Test-Diving時，函數會調用自己10次。函數使用一個參數來控制嵌套層次，而Test-NestLevel負責返回確切的深度數。
注意這里有個區別：Test-NestLevel返回絕對的嵌套層次，參數會紀錄這個函數調用自己多少次。如果Test-Diving被嵌入到另外一個函數中，絕對深度和相對深度會不同。
PS C:\&; Test-Diving -Depth 1
diving deeper to 1 meters...
calculated depth: 1
diving deeper to 2 meters...
calculated depth: 2
diving deeper to 3 meters...
calculated depth: 3
diving deeper to 4 meters...
calculated depth: 4
diving deeper to 5 meters...
calculated depth: 5
diving deeper to 6 meters...
calculated depth: 6
diving deeper to 7 meters...
calculated depth: 7
diving deeper to 8 meters...
calculated depth: 8
diving deeper to 9 meters...
calculated depth: 9
diving deeper to 10 meters...
calculated depth: 10
PS C:\&; { Test-Diving -Depth 1 }
diving deeper to 1 meters...
calculated depth: 2
diving deeper to 2 meters...
calculated depth: 3
diving deeper to 3 meters...
calculated depth: 4
diving deeper to 4 meters...
calculated depth: 5
diving deeper to 5 meters...
calculated depth: 6
diving deeper to 6 meters...
calculated depth: 7
diving deeper to 7 meters...
calculated depth: 8
diving deeper to 8 meters...
calculated depth: 9
diving deeper to 9 meters...
calculated depth: 10
diving deeper to 10 meters...
calculated depth: 11
PS C:\&;
Test-NestLevel總會返回從當前代碼的作用域到全局作用域的嵌套深度。
