In Powershell, get join-path to work with $null and empty string

Question

Powershell 5 says "no way Jose", can't join path with null or empty string. I say why not? Is there a way to get join-path to be more "Flexible" without adding more if-else blocks?

    $its_in_the_path = $true
    #$its_in_the_path = $false

    if ($its_in_the_path) {
        $mydir = ""
    }
    else {
        $mydir "C:\tool\path  
    }

    $tool = join-path $mydir "runit.exe"

Cannot bind argument to parameter 'Path' because it is an empty string.
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At + ~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidData: (:) [frunsim], ParameterBindingValidationException
    + FullyQualifiedErrorId : ParameterArgumentValidationErrorEmptyStringNotAllowed,frunsim

Answer 1

Join-Path will not allow $null values or [string]::Empty. You can use Path.Combine Method for that:

PS \> [System.IO.Path]::Combine($null, "runit.exe")
runit.exe

PS \> [System.IO.Path]::Combine('C:\', 'Documents', "runit.exe")
C:\Documents\runit.exe