Recursive Function Call : Powershell (Scope?)

Question

Having trouble getting my menus to work. I would like to make a menu class, but I'm stuck with v2. Each time I enter "1" at the "Main Menu", it will simply re-present me with the main menu instead of re-entering the function with the new $menuType.

function presentMenu{
param ([string]$menuType)

if($menuType = "Main"){
     Write-Host "MAIN MENU: 1.) Add Scanner 2.) Remove Scanner 3.) Lookup Scanner Config 4.) Exit"
     $command = Read-Host
     ##DEBUG## write-host $menuType

     if ($command -eq 1){
         presentMenu("addScaner")
     }
     elseif ($command -eq 2){

     }
     elseif ($command -eq 3){

     }
     elseif ($command -eq 4){
        exit
     }
     elseif ($command -eq 5){
        exit
     }
    else{
        presentMenu("Main")
    }
  }

elseif($menuType = "addScanner"){
    Write-Host "ADD SCANNER: 1.) From File 2.) From Input 3.) Back  4.) Exit"
    $command = Read-Host
    if ($command -eq 1){
        addScannerController("File")
    }
    if ($command -eq 2){
        addScannerController("Input")
    }
    if ($command -eq 3){
        presentMenu("Main")
    }
    if ($command -eq 4){
        exit
    }
    else{
        presentMenu("addScanner")
    }       
  }
}


try{
presentMenu("Main")
}
catch{
  Write-Error $_.Exception.ToString()
  Read-Host -Prompt "The above error occurred. Press Enter to exit."
}

The expected outcome when you enter "1" at the main menu, would be that you are presented with the "addScanner" menu. This really seems like a scope issue to me, but I can't seem to figure out how to correct it?

replace your call by presentMenu "addScanner" (without parenthesis). This is a typical gotcha when you start with powershell. No parenthesis for function calls. — David Brabant
– David Brabant, Commented Mar 30, 2017 at 11:56
Also consider using a switch statement rather than if..elseif..elseif.. — arco444
– arco444, Commented Mar 30, 2017 at 11:57
= is assignment, but not comparison. BTW, PowerShell is not functional language and, AFAIK, does not support tailcall optimization. — user4003407
– user4003407, Commented Mar 30, 2017 at 12:00

Bali C · Accepted Answer · 2017-03-30 12:05:56Z

1

You are using = to compare the parameter, you need to use -eq.

You also have a typo, missing an n in addScanner.

Here's a stripped down example:

function presentMenu
{
    param ([string]$menuType)
    if($menuType -eq "Main")
    {
         Write-Host "MAIN MENU: 1.) Add Scanner 2.) Remove Scanner 3.) Lookup Scanner Config 4.) Exit"
         $command = Read-Host
         if ($command -eq 1)
         {
             presentMenu addScanner
         }
    }
    elseif($menuType -eq "addScanner")
    {
        Write-Host "ADD SCANNER: 1.) From File 2.) From Input 3.) Back  4.) Exit"
        $command = Read-Host
        if ($command -eq 1)
        {
            Write-Host "Scanner added"
        }
    }
}

presentMenu Main

edited Mar 30, 2017 at 12:05

answered Mar 30, 2017 at 11:59

Bali C

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2 Comments

Christopher Over a year ago

Palm to face Yes -eq NOT =. Can you tell I'm new to PS? :D

Bali C Over a year ago

I do that all the time, occupational hazard of switching between languages!

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