# encoding: ascii
# api: powershell
# title: Demo-Pipepline
# description: Just a simple learning tool …
# version: 0.1
# type: function
# author: Joel Bennett
# license: CC0
# function: Demo-Pipeline
# x-poshcode-id: 5939
# x-archived: 2016-08-26T03:52:22
# x-published: 2016-07-16T19:19:00
#
# Made InputObject optional, so you can call it without any pipeline input
#
function Demo-Pipeline {
#.Synopsis
# Useful for demonstrating how pipeline output works
#.Example
# 1..3 | Demo-Pipeline Red | Demo-Pipeline Green -OutputFromBegin | Demo-Pipeline Blue
[CmdletBinding()]
param (
[Parameter(Position=0)]
[ConsoleColor]$Color,
[Parameter(Position=1,ValueFromPipeline=$true)]
[String[]]$InputObject,
[Switch]$OutputFromBegin,
[Switch]$OutputFromEnd
)
begin {
Write-Verbose "ENTER Begin $Color"
if ($PSBoundParameters.ContainsKey("InputObject")) {
Write-Warning "We don't process InputObject in begin, because that wouldn't be PowerShelly"
}
Write-Host "BEGIN ($Color)" -Foreground $Color
$HasOutput = $false
if($OutputFromBegin) {
$HasOutput = $true
Write-Output "$Color BEGIN OUTPUT"
}
Write-Verbose "EXIT Begin $Color"
}
process {
Write-Verbose "ENTER Process $Color"
# This happens for each item that comes through:
Write-Host "PROCESS: $InputObject ($Color)" -Fore $Color
# We pass through the InputObject for the next guy
Write-Output $InputObject
# We _add_ one output thing of our own..
if(!$HasOutput -and !$OutputFromEnd) {
$HasOutput = $true
Write-Output "$Color PROCESS OUTPUT"
}
Write-Verbose "EXIT Process $Color"
}
end {
Write-Verbose "ENTER End $Color"
# This happens just once, at the end (notice the last input object is still around):
Write-Host "END: $InputObject ($Color)" -Fore $Color
if($OutputFromEnd) {
$HasOutput = $true
Write-Output "$Color END OUTPUT"
}
Write-Verbose "EXIT End $Color"
}
}