當(dāng)你調(diào)用某個(gè)函數(shù)時(shí)，PowerShell會(huì)增加一次嵌套層次。當(dāng)一個(gè)函數(shù)調(diào)用了另一個(gè)函數(shù)，或著腳本，也會(huì)增加嵌套層次。今天分享一個(gè)函數(shù)，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(dāng)你調(diào)用的函數(shù)具有遞歸調(diào)用時(shí)，上面的函數(shù)非常有用，來(lái)看一個(gè)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(yùn)行Test-Diving時(shí)，函數(shù)會(huì)調(diào)用自己10次。函數(shù)使用一個(gè)參數(shù)來(lái)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(gè)區(qū)別：Test-NestLevel返回絕對(duì)的嵌套層次，參數(shù)會(huì)紀(jì)錄這個(gè)函數(shù)調(diào)用自己多少次。如果Test-Diving被嵌入到另外一個(gè)函數(shù)中，絕對(duì)深度和相對(duì)深度會(huì)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(huì)返回從當(dāng)前代碼的作用域到全局作用域的嵌套深度。