PowerShell: the mysterious -RemainingScripts parameter of ForEach-Object

Question

Short question: anyone has detailed information on -RemainingScripts parameter of ForEach-Object?

Long question:

I just started

Answer 1

I believe -remainingscripts (with attribute 'ValueFromRemainingArguments') is to enable an idiom like this from Windows Powershell in Action, an idiom which almost nobody knows (20% of Powershell is only documented in that book):

Get-ChildItem | ForEach {$sum=0} {$sum++} {$sum}

The blocks end up acting like begin process end. The parameters being used are actually -process and -remainingscripts.

trace-command -name parameterbinding { Get-ChildItem | ForEach-Object {$sum=0} {$sum++} {$sum} } -PSHost

That trace-command seems to confirm this.

Here's a simple demo of ValueFromRemainingArguments with scriptblocks.

function remaindemo {
  param ($arg1,  [Parameter(ValueFromRemainingArguments)]$remain)
  & $arg1
  foreach ($i in $remain) {
    & $i
  }
}

remaindemo { 'hi' } { 'how are you' } { 'I am fine' }

Other commands with ValueFromRemainingArguments parameters:

gcm -pv cmd | select -exp parametersets | select -exp parameters |
  where ValueFromRemainingArguments | 
  select @{n='Cmdname';e={$cmd.name}},name

Cmdname        Name
-------        ----
ForEach-Object RemainingScripts
ForEach-Object ArgumentList
Get-Command    ArgumentList
Get-Command    ArgumentList
Join-Path      AdditionalChildPath
New-Module     ArgumentList
New-Module     ArgumentList
Read-Host      Prompt
Trace-Command  ArgumentList
Write-Host     Object
Write-Output   InputObject