Powershell Cmdlet that takes params or a config file with name value pairs

gistfile1.txt

function foo {
    param (
        [parameter(Mandatory=$true,ParameterSetName = "config")]
        [String]$Configuration,
 
        [parameter(Mandatory=$true,ParameterSetName = "param")]
        [String]$Name,
 
        [parameter(Mandatory=$true,ParameterSetName = "param")]
        [String]$Email
    )
 
    if ($PsCmdlet.ParameterSetName -eq "config") {
        $params = Invoke-Expression ((Get-Content $Configuration) -join "`n")
        return (. $MyInvocation.MyCommand @params)
    }
 
    return "${Name}<${Email}>"
}