PowerShell实现统计函数嵌套深度

当你调用某个函数时，powershell会增加一次嵌套层次。当一个函数调用了另一个函数，或着脚本，也会增加嵌套层次。今天分享一个函数，它能告诉你的脚本嵌套的层次：

function test-nestlevel
{
$i = 1
$ok = $true
do
{
try
{
$test = get-variable -name host -scope $i
}
catch
{
$ok = $false
}
$i++
} while ($ok)
 
$i
}

当你调用的函数具有递归调用时，上面的函数非常有用，来看一个调用的示例:

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
 

当你运行test-diving时，函数会调用自己10次。函数使用一个参数来控制嵌套层次，而test-nestlevel负责返回确切的深度数。

注意这里有个区别：test-nestlevel返回绝对的嵌套层次，参数会纪录这个函数调用自己多少次。如果test-diving被嵌入到另外一个函数中，绝对深度和相对深度会不同。

 

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总会返回从当前代码的作用域到全局作用域的嵌套深度。