Powershell Add custom class to InitialSessionState of runspacepool

I can add a function to my runspacepool using initialsessionstate like this:

$initialSessionState = [InitialSessionState]::CreateDefault()
$definition = Get-Content Function:\Icmp-Ping -ErrorAction Stop   
$addMessageSessionStateFunction = New-Object System.Management.Automation.Runspaces.SessionStateFunctionEntry -ArgumentList 'Icmp-Ping', $definition
$initialSessionState.Commands.Add($addMessageSessionStateFunction)

Now u want u add a simple class definition in the same manner:

I tried to use add-type with no success, i also read about type tables, but cant find a matching example for runspacepools. The classes type is unknown to the script in the runspace. At this point I wonder if what i want is possible at all. On the other hand if I can introduce functions and sessionstatevariables like this why not classes?

Solution

For an external assembly you could add using a SessionStateAssemblyEntry:

$iss = [InitialSessionState]::CreateDefault()
$iss.Assemblies.Add([System.Management.Automation.Runspaces.SessionStateAssemblyEntry]::new(
    ...
    ...))

However for PowerShell classes this is not an option as far as I know, the alternatives are either hardcode the class definition in the runspace script itself:

$ps = [powershell]::Create().AddScript{
    class Test {
        static [string] SayHey() {
            return 'hey there!'
        }
    }
    [Test]::SayHey()
}
$ps.Invoke()

Or if you have the definitions in a ps1 file, you can dot source it in the runspace script. For this second option you could for example pass an array of paths to the runspace using a parameter, this is obviously not needed but might be cleaner than hardcoding the path in the runspace script itself.

$paths = @(
    'path\to\myTestClass.ps1'
    'path\to\myOtherTestClass.ps1'
)

$ps = [powershell]::Create().AddScript{
    param([string[]] $ClassesToLoad)

    $ClassesToLoad | ForEach-Object { . $_ }

    [Test]::SayHey()
}.AddParameters(@{ ClassesToLoad = $paths })
$ps.Invoke()