Using a variables string value in variable name

Question

It should work like:

$part = 'able'

$variable = 5

Write-Host $vari$($part)

And this should print "5", since that's the value of $variable.

I want to use this to call a method on several variables that have similar, but not identical names without using a switch-statement. It would be enough if I can call the variable using something similar to:

New-Variable -Name "something"

but for calling the variable, not setting it.

Editing to add a concrete example of what I'm doing:

Switch($SearchType) {
    'User'{
        ForEach($Item in $OBJResults_ListBox.SelectedItems) {
           $OBJUsers_ListBox.Items.Add($Item)
        } 
    }
    'Computer' {
        ForEach($Item in $OBJResults_ListBox.SelectedItems) {
            $OBJComputers_ListBox.Items.Add($Item)
        } 
    }
    'Group' {
        ForEach($Item in $OBJResults_ListBox.SelectedItems) {
            $OBJGroups_ListBox.Items.Add($Item)
        } 
    }
}

I want this to look like:

ForEach($Item in $OBJResults_ListBox.SelectedItems) {
   $OBJ$($SearchType)s_ListBox.Items.Add($Item)
}

Mathias R. Jessen · Accepted Answer · 2018-02-07 14:17:56Z

2

You're looking for Get-Variable -ValueOnly:

Write-Host $(Get-Variable "vari$part" -ValueOnly)

Instead of calling Get-Variable every single time you need to resolve a ListBox reference, you could pre-propulate a hashtable based on the partial names and use that instead:

# Do this once, just before launching the GUI:
$ListBoxTable = @{}
Get-Variable OBJ*_ListBox|%{
  $ListBoxTable[($_.Name -replace '^OBJ(.*)_ListBox$','$1')] = $_.Value
}

# Replace your switch with this
foreach($Item in $OBJResults_ListBox.SelectedItems) {
    $ListBoxTable[$SearchType].Items.Add($Item)
}

edited Feb 7, 2018 at 14:17

answered Feb 7, 2018 at 12:39

Mathias R. Jessen

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3 Comments

Viktor Axén Over a year ago

This looks right. Can I use this to call a method as well? '$(Get-Variable "vari$part" -ValueOnly).methodname()'

Viktor Axén Over a year ago

This worked, although my GUI runs noticeably slower when using this method rather than the switch-statement. Any Idea as to why and if it's solveable in another way than this and the switch-statement?

Mathias R. Jessen Over a year ago

@ViktorAxén Instead of doing the variable lookup everytime, you could create a hashtable once and use that for the lookup

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