PowerShell Pipeline

What I Like in PowerShell V5, Part 2: New Features

• By Boe Prox
• 09/29/2016

Continuing from where I left off with my previous article on some things that I like about PowerShelll V5, I am going to move away from the new cmdlets and parameters and instead look at some other features which are available in PowerShell V5 such as Classes, enhanced scriptblock logging, setting a global transcript and additional streams. I do want to remind you that I am not covering version 5.1 in this series and am just focusing on things that came out with version 5.0.

A Quick Look at Classes
PowerShell classes help define a type of object by building out its properties, methods and how you can create the object by using constructors within the class. The use for this was to support Desired State Configuration (DSC). But, as with most things in IT, something that had a singular purpose can quickly become used for other things that had not been thought of before. Although, I am willing to bet that the PowerShell team knew that the use of classes would extend far beyond just DSC use. Before this, we had to make do with New-Object PSObject for PowerShell V1/2,[pscustomobject] for PowerShell V3/4 and had to use Add-Member to build out script methods or we would write C# code and use Add-Type to call in the classes that were defined to use to create objects.

So with that, let's step through a small example of creating a class that includes the following items:

• Properties
• Hidden Property
• Method
• Default Constructor (no parameters)
• Constructor with parameters

class House {

  #Parameters  which define various parts of the house

  [string]$Color

  [int]$NumberBedrooms

  [int]$NumberBathrooms

  #The hidden  property is something that we do not want publicly shown when

  #the object  is displayed

  hidden[int]$NumberOwners
    #Methods are  defined here that an be used to do a variety of things

  #In this case  we have a Sell and Paint method to change owners of the house

  #or to change  the color of the house

  [void]Sell() {

  $This.NumberOwners =  $this.NumberOwners+1

  }

  [void]Paint([string]$Color) {

  $This.Color = $Color

  }
    #Constructors  are defined here to allow us different options to build the house

  #such as  using a default constructor or being able to supply different parameters

  House  () {

  $This.Color = 'White'

  $This.NumberBedrooms =  2

  $This.NumberBathrooms =  1

  $This.NumberOwners =  1

  }
    House  ([string]$Color) {

  $This.Color = $Color

  $This.NumberBedrooms =  2

  $This.NumberBathrooms =  1

  $This.NumberOwners =  1

  }

  House  ([string]$Color,[int]$NumberBedrooms)  {

  $This.Color = $Color

  $This.NumberBedrooms =  $NumberBedrooms

  $This.NumberBathrooms =  1

  $This.NumberOwners =  1

  }

  House  ([string]$Color,[int]$NumberBedrooms,[int]$NumberBathrooms)  {

  $This.Color = $Color

  $This.NumberBedrooms =  $NumberBedrooms

  $This.NumberBathrooms =  $NumberBathrooms

  $This.NumberOwners =  1

  }

  } 

Here we have our properties at the top of our house class, followed by the methods which allow us to make changes to the house object and lastly we define our constructors on the house so we know how to build it properly. Also note the use of $This in the scriptblocks which means that it will use $This as the current object (being itself) to adjust the properties.

Now that we have defined our class, we can show some examples on building out the object with the allowed constructors that we have configured.

Fun fact: Also in PowerShell V5, there is now a New() static method which makes it easier to build out an object, but if you leave out the parenthesis, you can get a list of all of the possible ways to build the object by looking at the constructors.

[house]::New 

I'll go ahead and use the default constructor to build my house and then we can look at giving it a paint job later on.

$House = [house]::New()

  $House 

  $House.Paint('Green')

$House 

What you do not see is the NumberOwners property being shown. That is because we said to hide this property unless it is explicitly called.

$House.NumberOwners

  $House.Sell()

$House.NumberOwners 

While using classes may not be for everyone, I encourage you to at least check them out and see if they happen work with something that you are working on.

Defining a Global Transcript
This and the following section deal with a more security focused side of PowerShell in knowing what is being run on a system and also being able to log what is running so there is some sort of accountability in case something does go south.

In the case of a global transcript, we now have a group policy that can be enabled to allow complete transcript logging across all computers that receive it. This is much nicer than a per-user transcript logging that you would normally have that would write to their own home directories.  To enable this, you would normally use the group policy management console (gpmc) and navigate down to the Computer configuration>Administrative Templates>Windows Components>Windows PowerShell. Within that you will see the setting for the Turn on PowerShell Transcriptions. Set the setting to Enabled. From there you can direct where the transcript logs will be outputted to and also decide if you want to include the invocation headers.