Anonymous Recursive Function

April 28, 2022

Is it possible to create an anonymous Recursive Function in PowerShell? (if yes, how?)

I have a recursive object and using a recursive function to drill down through the properties, like:

$Object = ConvertFrom-Json '
{
    "Name" : "Level1",
    "Folder" : {
        "Name" : "Level2",
        "Folder" : {
            Name : "Level3"
        }       
    }
}'

Function GetPath($Object) {
    $Object.Name
    if ($Object.Folder) { GetPath $Object.Folder }
}

(GetPath($Object)) -Join '\'

Level1\Level2\Level3

The function is relative small and only required ones, therefore I would like to directly invoke it as an anonymous function, some like:

(&{
    $Object.Name
    if ($Object.Folder) { ???? $Object.Folder }
}) -Join '\'

Is this possible in PowerShell?
If yes, how can I (as clean as possible) refer to the current function at ?????

>Solution :

Unfortunately there is not much documentation on this topic but you could execute the anonymous script block by calling $MyInvocation.MyCommand.ScriptBlock, a simple example:

&{
    param([int] $i)

    if($i -eq 10) { return $i }
    ($i++)
    & $MyInvocation.MyCommand.ScriptBlock $i
}

# Results in 0..10

Using your current code and Json as example:

(&{
    param($s)

    $s.Name
    if ($s.Folder) { & $MyInvocation.MyCommand.ScriptBlock $s.Folder }
} $Object) -Join '\'

# Results in Level1\Level2\Level3