This is a useful template for starting a CmdLet that needs to work in a PipeLine or by passing parameters.

Processing is implemented in the processItem sub-function.  All the “–ne $null” conditions handle the differences between pipeline and parameter invocation.

function Test-PipelineOrParm ($parm)

{

  begin

  {

    function processItem($item)

    {

      # Implement processing in this function

      "processItem $item"

    }

    if ($parm -ne $null)

    {

      foreach ($item in $parm)

      {

        "begin $(processItem $item)"

      }

    }

  }

  process

  {

    if ($_ -ne $null)

    {

      "process $(processItem $_)"

    }

  }

  end

  {

    Write-Host "Done"

  }

}

These two examples demonstrate calling the template.

Write-Host "Test Pipeline processing"

Get-ChildItem | Test-PipelineOrParm

Write-Host "Test Parm processing"

Test-PipelineOrParm $(Get-ChildItem)