Creating objects with methods in PowerShell - Part 2

gistfile1.ps1

# Code from my blog entry at http://betterlivingthroughcode.blogspot.com/2014/02/creating-objects-with-methods-in.html

$myObj1 = New-Object -TypeName PSObject -Property @{Prop1 = "1"; Prop2 = 2}
$myObj2 = [pscustomobject]@{Prop1 = "1"; Prop2 = 2}

$myObj2 | Get-Member

$myObj2.Prop1 = 42

$myObj2 | Get-Member

$myObj3 = New-Module -ScriptBlock {
    [string]$Prop1 = "1"
    [int]$Prop2 = 2
    
    Export-ModuleMember -Function * -Variable *
} -AsCustomObject

$myObj3 | Get-Member

$myObj3.Prop2 = "Does this work?"

$myBook = New-Module -ScriptBlock {
  [string]$Title = ""
  [string]$Author = ""
  [int]$NumberSold = 0
  [System.Nullable``1[[System.DateTime]]]$DatePublished = $null
  
  Function WriteSummary() {
    "$($this.Title) by $($this.Author), published on $(($this.DatePublished).ToString("yyyy-MM-dd")) has sold $($this.NumberSold) copies."
  }

  Export-ModuleMember -Function * -Variable *
} -AsCustomObject

$myBook.Author = "Robert Heinlein"
$myBook.Title = "The Moon is a Harsh Mistress"
$myBook.DatePublished = "1966-03-17"
$myBook.NumberSold = 1000000
$myBook.WriteSummary()

Function New-Book {
  param([string]$Title = "", [string]$Author = "", [int]$NumberSold = 0, [System.Nullable``1[[System.DateTime]]]$DatePublished = $null)

  $newBook = New-Module -ScriptBlock {
    [string]$Title = ""
    [string]$Author = ""
    [int]$NumberSold = 0
    [System.Nullable``1[[System.DateTime]]]$DatePublished = $null
   
    Function WriteSummary() {
      "$($this.Title) by $($this.Author), published on $(($this.DatePublished).ToString("yyyy-MM-dd")) has sold $($this.NumberSold) copies."
    }

    Export-ModuleMember -Function * -Variable *
  } -AsCustomObject

  $newBook.Author = $Author
  $newBook.Title = $Title
  $newBook.DatePublished = $DatePublished
  $newBook.NumberSold = $NumberSold

  $newBook
}

$jb = New-Book -Title "Jitterbug Perfume" -Author "Tom Robbins" -DatePublished "1984-09-07" -NumberSold 400000
$hhgtg = New-Book -Title "The Hitchhiker's Guide to the Galaxy" -Author "Douglas Adams" -DatePublished "1979-10-12" -NumberSold 42
$jb.WriteSummary()
$hhgtg.WriteSummary()