Chapter4/4.6_AdvancedFunctions/4.6.2_Parameter/ParameterAlias.ps1

function Get-DirectorySize {
    [CmdletBinding()]
    param(
      [parameter(Mandatory = $true, ValueFromPipeline = $true, ValueFromPipelineByPropertyName = $true)]
      [Alias("Path", "PSPath")]
      [string[]]$LiteralPath,
  
      [parameter(ValueFromPipelineByPropertyName = $true)]
      [int]$OverSize
    )
  
    process {
      $measure = Get-ChildItem -LiteralPath $LiteralPath -Recurse -Force -File | Measure-Object -Sum Length
      $output = [pscustomobject]@{
        Path      = $LiteralPath
        FileCount = $measure.Count
        Sum       = $measure.Sum
        OverSize  = $measure.Sum -ge $OverSize
      }
      Write-Output $output
    }
  }