TopolearnWhen no cmdlet exists, the entire .NET library is one line away, and classes give you real types.
PowerShell runs on .NET, so every .NET type is available. Static members use [Type]::Member: [math]::Round(2.567, 2), [System.IO.Path]::GetExtension($f), [datetime]::Parse('2026-01-15'), [guid]::NewGuid(). Common namespaces may be shortened ([IO.Path]), and a using namespace System.Text line at the top of a script lets you write [StringBuilder]. Create instances with [Type]::new(args) (or the older New-Object).
PowerShell classes (since 5.0) define real .NET types with typed properties, constructors, methods, static members, inheritance and enums:
- methods must declare a return type and use
returnexplicitly; unlike functions, stray values are not output, - reference the instance with
$this, - override
ToString()to control how objects appear in strings.
Classes are useful for validated data structures and for advanced features like custom validation attributes and DSC resources. Limitations: a class must be defined before the code that uses it is parsed, and changes to a class in a module need a new session to reload.
Add-Type -TypeDefinition compiles C# source on the fly, for performance-critical code or P/Invoke calls into native APIs. Compiled types cannot be unloaded from the session, so rename them while iterating.
Example
[System.IO.Path]::GetExtension('report.final.csv') # .csv
[math]::Sqrt(144) # 12
[datetime]::Parse('2026-01-15').DayOfWeek # Thursday
$sb = [System.Text.StringBuilder]::new()
[void]$sb.Append('fast ').Append('strings')
$sb.ToString() # fast strings
class Server {
[string]$Name
[int]$Cpu
Server([string]$name, [int]$cpu) { $this.Name = $name; $this.Cpu = $cpu }
[bool] IsBusy() { return $this.Cpu -gt 80 }
[string] ToString() { return "$($this.Name) ($($this.Cpu)%)" }
}
$s = [Server]::new('web1', 92)
$s.IsBusy() # True
"$s" # web1 (92%)
Add-Type -TypeDefinition 'public static class Calc { public static int Twice(int x) { return x * 2; } }'
[Calc]::Twice(21) # 42Remember
- [Type]::StaticMember and [Type]::new() reach all of .NET
- Class methods need return types and explicit return
- Add-Type compiles C# for speed or native interop
Watch out for
- Expecting a class method to output values like a function: only the return value comes back.