PowerShell pass array as a reference

Question

I'm building a menu and want to pass an array to a function as a reference.

When I'm passing just the reference everything works fine. But when I want to pass a second parameter, it won't work with an "ParameterBindingArgumentTransformationException". And I do not understand why.

Here is the - working- minimal code:

function Menu {
    param([Ref]$mi)
    Write-Host "var"
    Write-Host $mi.value[0].cmd
    Write-Host $mi.value[1].desc
    Write-Output 0
}


function MainMenu {
    $mm = @(@{desc='Windows Tools';cmd='WinToolsMenue'},
            @{desc='copy setup.exe';cmd='setupexe'},
            @{desc='gpupdate (Policy)';cmd='cmd /c gpupdate /force'},
            @{desc='Exit';cmd='break'})
    $a = Menu([Ref]$mm)
}

& MainMenu

The problem-code:

function Menu {
    param([Ref]$mi, $b)
    Write-Host $b
    Write-Host $mi.value[0].cmd
    Write-Host $mi.value[1].desc
    Write-Output 0
}

function MainMenu {

    $mm = @(@{desc='Windows Tools';cmd='WinToolsMenue'},
            @{desc='copy setup.exe';cmd='setupexe'},
            @{desc='gpupdate (Policy)';cmd='cmd /c gpupdate /force'},
            @{desc='Exit';cmd='break'} )
    $mm

    $a = Menu([Ref]$mm, "b")
}

& MainMenu

Almost tried ([Ref]$mi), $b or ([Ref]$mi, $b), but it won't work. Someone out there who knows what I'm doing wrong?

Bacon Bits · Accepted Answer · 2015-09-26 16:42:26Z

2

$a = Menu ([Ref]$mm, "b")

That's not how you call a function. Remember, the comma is an operator for arrays, and parentheses indicate a expression that gets evaluated first. That doesn't change just because you're calling a function. This says, "Call function Menu, with the first parameter an array with two elements of [Ref]$mm and "b". Essentially, you're calling this:

$a = Menu -mi @([Ref]$mm, "b") -b $null

You need to specify:

$a = Menu ([Ref]$mm) "b"

Or:

$a = Menu -mi ([Ref]$mm) -b "b"

answered Sep 26, 2015 at 16:42

Bacon Bits

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1 Comment

Mago Over a year ago

ok, got it. Thank you for your replay. References need to be evaluated and comma is an array separator, that was my fault. Will remember this

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