powershell indentation

Question

I'm writing a large script that deploys an application. This script is based on several nested function calls.

Is there any way to "ident" the output based on the depth?

For example, I have:

function myFn()
{
    Write-Host "Start of myfn"
    myFnNested()
    Write-Host "End of myfn"
}
function myFnNested()
{
    Write-Host "Start of myFnNested"
    Write-Host "End of myFnNested"
}

Write-Host "Start of myscript"
Write-Host "End of myscript"

The output of the script will be :

Start of myscript
Start of myfn
Start of myfnNested
End of myFnNested
End of myFn
End of myscript

What I want to achieve is this output :

Start of myscript
  Start of myfn
    Start of myfnNested
    End of myFnNested
  End of myFn
End of myscript

As I don't want to hardly code the number of spaces (since I does not know the depth level in complex script). How can I simply reach my goal ?

Maybe something like this?

function myFn()
{
    Indent()
    Write-Host "Start of myfn"
    myFnNested()
    Write-Host "End of myfn"
    UnIndent()
}
function myFnNested()
{
    Indent()
    Write-Host "Start of myFnNested"
    Write-Host "End of myFnNested"
    UnIndent()
}

Write-Host "Start of myscript"
Write-Host "End of myscript"

Answer 1

You could use a wrapper function around write-host which used $MyInvocation to determine the stack depth to create a number of spaces to prefix the message.

Combine this with the -scope ‹n› parameter of Get-Variable to pull out each calling level… something like the showstack function adapted from Windows PowerShell In Action (Payette, 1^st Ed):

function ShowStack {
  trap { continue; }
  0..100 | Foreach-Object {
    (Get-Variable -scope $_ 'MyInvocation').Value.PositionMessage -replace "`n"
  }
}

You'll need the maximum value of $_ in the pipeline before Get-Variable fails for scope count being too high.

Answer 2

Check out this script http://poshcode.org/scripts/3386.html

If you load up that Write-Verbose wrapper, you can set $WriteHostAutoIndent = $true and then just call Write-Host and it will be indented based on stack depth. So given these functions as you defined them originally:

function myFn()
{
   Write-Host "Start of myfn"
   myFnNested
   Write-Host "End of myfn"
}
function myFnNested()
{
   Write-Host "Start of myFnNested"
   Write-Host "End of myFnNested"
}

With no changes, you can just dot-source a script file with that Write-Host wrapper function in it:

C:\PS> . C:\Users\Jaykul\Documents\WindowsPowerShell\PoshCode\3386.ps1

And then merely set the preference variable before you call your function:

C:\PS> $WriteHostAutoIndent = $true
C:\PS> myFn
  Start of myfn
    Start of myFnNested
    End of myFnNested
  End of myfn

Beautiful indented output, like magic ;-)