http://aerie.hatenablog.jp/entry/2014/05/22/133615

Filter-Sample.ps1

filter Filter-Sample1 {

  Write-Host "process: 複数回実行されます: $_"

}

filter Filter-Sample2 {

  param($X)

  Write-Host "process: 複数回実行されます: $_; $X"

}

1,2,3 | Filter-Sample1

4,5,6 | Filter-Sample2 -X ほげ

Pipeline-Sample.ps1

function Pipeline-Sample {

  param(
    [Parameter(Mandatory, Position = 0, ValueFromPipeline)]
    [int[]] $X)

  begin {

    Write-Host 'begin: 一回だけ実行されます'

  }
  process {

    @($X) | % {
      Write-Host "process: 複数回実行されます: $_"
    }

  }
  end {

    Write-Host 'end: 一回だけ実行されます'

  }
}

Write-Host '=== パイプライン経由で実行 ==='
1,2,3 | Pipeline-Sample

Write-Host '=== 引数経由で実行 ==='
Pipeline-Sample 4,5,6

Using-Resource.ps1

function Using-Resource {

  [CmdletBinding()]

  param(
    [Parameter(Mandatory, Position = 0, ValueFromPipeline)]
    [int[]] $X)

  begin {

    $resource = New-Object PSCustomObject |
      Add-Member ScriptMethod Initialize { Write-Host '初期化処理をしたつもり' } -PassThru |
      Add-Member ScriptMethod CleanUp { Write-Host 'クリーンアップ処理をしたつもり' } -PassThru

    $resource.Initialize()

    function CleanUp-Resource {
      $resource.CleanUp()
    }

  }
  process {

    @($X) | % {

      try {
        Write-Host "処理中：$_"

        if ($_ -lt 0) {
          throw 'あかん'
        }

        Write-Host "処理完了：$_"
      }
      catch {
        CleanUp-Resource
        throw
      }

    }

  }
  end {
    CleanUp-Resource
  }

}