PowerShell Function for Creating a New Dynamic Variable

function New-DynamicVariable
{
    ##############################################################################
    ##
    ## New-DynamicVariable
    ##
    ## From Windows PowerShell Cookbook (O'Reilly)
    ## by Lee Holmes (https://www.leeholmes.com/tags/guide/)
    ##
    ##############################################################################

    <#
    .SYNOPSIS
        Creates a variable that supports scripted actions for its getter and setter

    .EXAMPLE
        PS > .\New-DynamicVariable GLOBAL:WindowTitle `
             -Getter { $host.UI.RawUI.WindowTitle } `
             -Setter { $host.UI.RawUI.WindowTitle = $args[0] }

        PS > $windowTitle
        Administrator: C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe
        PS > $windowTitle = "Test"
        PS > $windowTitle
        Test

    #>

    param(
        ## The name for the dynamic variable
        [Parameter(Mandatory = $true)]
        $Name,

        ## The scriptblock to invoke when getting the value of the variable
        [Parameter(Mandatory = $true)]
        [ScriptBlock] $Getter,

        ## The scriptblock to invoke when setting the value of the variable
        [ScriptBlock] $Setter
    )

    Set-StrictMode -Version 3

    Add-Type @"
    using System;
    using System.Collections.ObjectModel;
    using System.Management.Automation;

    namespace Lee.Holmes
    {
        public class DynamicVariable : PSVariable
        {
            public DynamicVariable(
                string name,
                ScriptBlock scriptGetter,
                ScriptBlock scriptSetter)
                    : base(name, null, ScopedItemOptions.AllScope)
            {
                getter = scriptGetter;
                setter = scriptSetter;
            }
            private ScriptBlock getter;
            private ScriptBlock setter;

            public override object Value
            {
                get
                {
                    if(getter != null)
                    {
                        Collection<PSObject> results = getter.Invoke();
                        if(results.Count == 1)
                        {
                            return results[0];
                        }
                        else
                        {
                            PSObject[] returnResults =
                                new PSObject[results.Count];
                            results.CopyTo(returnResults, 0);
                            return returnResults;
                        }
                    }
                    else { return null; }
                }
                set
                {
                    if(setter != null) { setter.Invoke(value); }
                }
            }
        }
    }
"@

    ## If we've already defined the variable, remove it.
    if(Test-Path variable:\$name)
    {
        Remove-Item variable:\$name -Force
    }

    ## Set the new variable, along with its getter and setter.
    $executioncontext.SessionState.PSVariable.Set((New-Object Lee.Holmes.DynamicVariable $name,$getter,$setter))
}