Is there a way to return to the command prompt temporarily

Question

How would One allow users to "Pause the current Pipeline and return to the command prompt" and later resume in a powershell script?

I stumbled upon this line in a blog post about User Interaction in Powershell

$suspend = New-Object System.Management.Automation.Host.ChoiceDescription "&Suspend", "Pause the current pipeline and return to the command prompt. Type ""exit"" to resume the pipeline."

It was a mock option in a prompt imitating the appearance of a native command (Remove-Item). Lo and behold: That command actually Implements that behavior. Doing a quick Google Search, I did not find an implementation in a script.

Answer 1

You can use $Host.EnterNestedPrompt() to suspend the current operation to enter a "nested" prompt - execution will resume once you exit it (using either exit or $Host.ExitNestedPrompt()):

function f {
  param([switch]$Intervene)

  $abc = 123

  if($Intervene.IsPresent){
    $host.EnterNestedPrompt()
  }

  Write-Host "`$abc has value '$abc'"
}

Now try invoking the function with and without the -Intervene switch:

Answer 2

Mathias R. Jessen's helpful answer is undoubtedly the best solution for your use case.

Because there is functional overlap, let me offer a solution for on-demand debugging of a script or function, using the Wait-Debugger cmdlet, which also enters a nested prompt in the current scope, while offering additional, debugging-specific functionality to step through the code.

function foo {
  'Entering foo.'
  if (0 -eq $host.ui.PromptForChoice('Debugging', 'Enter the debugger?', ('&Yes', '&No'), 1)) {
    Wait-Debugger
  }
  'Exiting foo.'
}

Executing foo presents a yes/no prompt for whether the debugger should be entered.

The debugging prompt can be exited with exit or simply c (one of the debugging-specific commands; h shows them all).