Add-NoteProperty.ps1

<#
.SYNOPSIS
Adds a NoteProperty to a PSObject, calculating the value with the object in context.

.DESCRIPTION
The Add-Member cmdlet can either add a property with a single static value to objects
in the pipeline, or add a script property to objects which executes each time it's used.

This adds a static value to each object, but calculated from each object.

.INPUTS
System.Management.Automation.PSObject item to add a note property to.

.OUTPUTS
System.Management.Automation.PSObject with the added note property.

.FUNCTIONALITY
Properties

.LINK
Add-Member

.EXAMPLE
Get-ChildItem Get-*.ps1 |Add-NoteProperty.ps1 Size {Format-ByteUnits.ps1 $Length -Precision 1} -Properties Length -PassThru |Format-Table Size,Name -AutoSize

|  Size Name
|  ---- ----
| 8.1KB Get-AspNetEvents.ps1
|   840 Get-AssemblyFramework.ps1
|38.3KB Get-CharacterDetails.ps1
| 1.1KB Get-ClassicAspEvents.ps1
| 1.3KB Get-CommandPath.ps1
| 1.2KB Get-ConfigConnectionStringBuilders.ps1
| 4.9KB Get-ConsoleColors.ps1
| 1.4KB Get-ContentSecurityPolicy.ps1
|   617 Get-Dns.ps1
| 2.4KB Get-EnumValues.ps1
|   6KB Get-IisLog.ps1
| 1.9KB Get-LibraryVulnerabilityInfo.ps1
| 2.7KB Get-DotNetFrameworkVersions.ps1
|   969 Get-RepoName.ps1
| 3.3KB Get-SslDetails.ps1
| 4.2KB Get-SystemDetails.ps1
| 6.8KB Get-TypeAccelerators.ps1
| 1.2KB Get-XmlNamespaces.ps1

.EXAMPLE
Get-ChildItem Get-*.ps1 |Add-NoteProperty.ps1 @{Size={Format-ByteUnits.ps1 $_.Length -Precision 1};Ext={$_ |Split-Path -Extension};Hat='Y'} -PassThru |Format-Table Size,Name,Ext,Hat -AutoSize

|  Size Name                                   Ext  Hat
|  ---- ----                                   ---  ---
|   928 Get-ADServiceAccountInfo.ps1           .ps1 Y
| 1.9KB Get-ADUserStatus.ps1                   .ps1 Y
| 8.1KB Get-AspNetEvents.ps1                   .ps1 Y
| 1.1KB Get-AssemblyFramework.ps1              .ps1 Y
| 2.9KB Get-CachedCredential.ps1               .ps1 Y
|34.5KB Get-CharacterDetails.ps1               .ps1 Y
#>

[CmdletBinding()][OutputType([psobject])] Param(
# The name of the NoteProperty to add to the object.
[Parameter(ParameterSetName='NameValue',Position=0,Mandatory=$true)][string] $Name,
# The expression to use to set the value of the NoteProperty.
[Parameter(ParameterSetName='NameValue',Position=1,Mandatory=$true)][ScriptBlock] $Value,
# A hashtable mapping names of new properties to script blocks generating the values of those properties.
[Parameter(ParameterSetName='NewProperties',Position=0,Mandatory=$true)][hashtable] $NewProperties,
# Properties of the input object to include as variables in the script block scope.
[Alias('Import')][string[]] $Properties = @(),
# The object to add the NoteProperty to.
[Parameter(ValueFromPipeline=$true,Mandatory=$true)][PSObject] $InputObject,
# Returns the object with the NoteProperty added. Normally there is no output.
[switch] $PassThru,
# Overwrite an existing property.
[switch] $Force
)
Process
{
	[psvariable[]] $context = New-Object psvariable _,$InputObject
	if($Properties -and $Properties.Length)
	{
		if($Properties[0] -eq '*')
		{
			$context += $InputObject.PSObject.Properties |
				ForEach-Object {New-Object psvariable $_.Name,$_.Value}
		}
		else
		{
			$context += $InputObject.PSObject.Properties |
				Where-Object Name -in $Properties |
				ForEach-Object {New-Object psvariable $_.Name,$_.Value}
		}
	}
	switch($PSCmdlet.ParameterSetName)
	{
		NameValue
		{
			$v = $Value.InvokeWithContext($null,$context,$null) |Select-Object -First 1
			Add-Member -InputObject $InputObject -MemberType NoteProperty -Name $Name `
				-Value $v -PassThru:$PassThru -Force:$Force
		}
		NewProperties
		{
			$NewProperties.Keys |ForEach-Object {
				$v = $NewProperties[$_]
				if($v -is [scriptblock]) {$v = $v.InvokeWithContext($null,$context,$null) |Select-Object -First 1}
				Add-Member -InputObject $InputObject -MemberType NoteProperty -Name $_ -Value $v -Force:$Force
			}
			if($PassThru) {Write-Output $InputObject}
		}
		default {Stop-ThrowError.ps1 'Unknown parameter set' -TargetObject $PSBoundParameters}
	}
}