Powershell add-member. Add a member that's an ArrayList? - arrays

Question

The Powershell "add-member" command is very useful. I use it to add properties to custom objects. Sometimes I set a member as an array to hold multiple objects. Is it possible to add an ArrayList as a member on a custom object?
Imagine a list of articles has properties "index", "title", and "keywords." In Powershell, you could put this code in a loop:
for($i = 0; $i -lt 100; $i++) {
$a = new-object -TypeName PSObject
$a | Add-Member -MemberType NoteProperty -Name index -Value $i
$a | Add-Member -MemberType NoteProperty -Name title -Value "Article $i"
$a | Add-Member -MemberType NoteProperty -Name keywords -Value #()
$articles += $a
}
You'd end up with an array, $articles, of Article objects, each with members index, title, and keywords. Furthermore, the keywords member is an array that can have multiple entries:
$articles[2].keywords += "Stack Exchange", "Powershell", "ArrayLists"
$articles[2].keywords[2]
Powershell
This meets most of my needs, but I just don't like dealing with arrays. ArrayLists are just easier to work with, if only because
$arrayList1.remove("value")
is so much more intuitive than
$array1 = $array1 |? {$_ new "value"}
Is there a way with Add-Member to add an ArrayList as a member? Or am I stuck with arrays? If Powershell doesn't support thi snatively, could I pop in some C# code to make a new class with an ArrayList as a member?

Answer 1

$arr = #("one","two","three")
$arr.GetType()
IsPublic IsSerial Name BaseType
-------- -------- ---- --------
True True Object[] System.Array
$a = new-object -TypeName PSObject
[System.Collections.ArrayList]$arrList=$arr
$a | Add-Member -MemberType NoteProperty -Name ArrayList -value $arrlist
$a.ArrayList
one
two
three
$a.ArrayList.remove("one")
$a.ArrayList
two
three
To add a blank ArrayList to your custom object just use
$a | Add-Member -MemberType NoteProperty -Name ArrayList -value (New-object System.Collections.Arraylist)

Answer 2

I find all this Add-Member stuff to be confusing for data only. In powershell 3, you can just make an object from a hashtable, and use a little thing I learned from a blog about using Invoke to get a Collection typed object:
$myObject = [PSCustomObject]#{
index = $idx;
title = $title;
keywords = {#()}.Invoke()
}
$myObject.keywords.Add("foo")
$myObject.keywords.Add("bar")
Write-Host "Original"
$myObject.keywords
Write-Host
Write-Host "New:"
[void]$myObject.keywords.Remove("foo")
$myObject.keywords
Write-Host
Original
foo
bar
New:
bar