The Wiert Corner – irregular stream of stuff

I need to write some tests for this, but it looks like you can use the keywords Begin/Process/End with code blocks when the script block is inside a .ForEach member call.

The behaviour seems to be the same as if these blocks are part of a function that executes inside a pipeline (Begin and End are executed once; Process is executed for each item in the pipeline).

It’s hard to Google on this, as all hits of all queries I tried got me into these keywords in the context of functions.

The below links are on my reading list.

Microsoft documentation:

• [WayBack] about_Arrays: Methods of Arrays – PowerShell | Microsoft Docs
• [WayBack] ForEach-Object
• [WayBack] about_Script_Blocks – PowerShell | Microsoft Docs
• [WayBack] about_Functions – PowerShell | Microsoft Docs
• [WayBack] about_Functions_Advanced – PowerShell | Microsoft Docs
• [WayBack] about_Functions_Advanced_Methods – PowerShell | Microsoft Docs

SS64 docs (which has guidance on which of the 3 foreach constructs to use when):

• [WayBack] ForEach method – PowerShell – SS64.com
• [WayBack] ForEach – PowerShell – SS64.com on the foreach statement)
• [WayBack] ForEach-Object % – PowerShell – SS64.com (aliased ForEach and %)
• [WayBack] Function Begin Process End – PowerShell – SS64.com[WayBack] Powershell Arrays – PowerShell – SS64.com
• [WayBack] Scriptblocks – PowerShell – SS64.com

Social media and blog posts:

• [WayBack] PowerShell: $array.ForEach({}) | Saved Keystrokes
• [WayBack] PowerShell 4.0 Where and ForEach Method Syntax – TechNet Articles – United States (English) – TechNet Wiki
• [WayBack] Extending the Reach of ForEach in PowerShell — Microsoft Certified Professional Magazine Online
• [WayBack] PowerShell functions: begin, process and end blocks
• [WayBack] $input gotchas | Dmitry’s Blog: Cloud, PowerShell and beyond
• [WayBack] Advanced PowerShell Functions: Begin to Process to End – SAPIEN Blog (shows what happens when nesting functions having these blocks)
• [WayBack] PowerShell – Begin Process End – CodeAndKeep.Com – Code and keep calm…
• [WayBack] Implement Pipeline Support by making proper use of begin, process and end blocks in PowerShell functions – mohitgoyal.co

StackOverflow entries:

• [WayBack] powershell – How does begin/process/end save the need for foreach? Still needed for the parameter isn’t it? – Stack Overflow
• [WayBack] PowerShell: the mysterious -RemainingScripts parameter of ForEach-Object – Stack Overflow
• [WayBack] powershell – Use Begin, Process, End in Scriptblock – Stack Overflow
• [WayBack] Difference between ForEach and ForEach-Object in powershell – Stack Overflow
• [WayBack] PowerShell: How to get count of piped collection? – Stack Overflow
• [WayBack] powershell – Nested function inside a function with begin/process/end blocks? – Stack Overflow
• [WayBack] PowerShell Pipeline iteration – Stack Overflow
• [WayBack] powershell – How to query registry values skipping the PS* ones – Stack Overflow (thanks [WayBack] User Keith Miller – Stack Overflow / [WayBack] Keith A. Miller – Microsoft Community for bringing this to my attention)
  

  I know this is truly old, but here’s a function I added to my Profile to facilitate registry exploration:

  Function Get-KeyProperty  {
  Param(
      [Parameter(Mandatory=$true,ValueFromPipeline=$true)]
      [ValidateScript( {(Resolve-Path $_).Provider.Name -Like 'Registry'} )]
      [String[]]
      $Path,
      [String[]]
      $Name=@("*")
  )
  Process {
      $Name.ForEach({ (Get-Item $Path).Property -like $_}).ForEach({
          Begin {$Hash = @{}}
          Process { $Hash += @{ $_ = (Get-Item $Path).GetValue($_)} }
          End {[PSCustomObject]$Hash}
      })
  }}

  …

   

–jeroen