How to use Windows.Storage.Streams.DataWriter with PowerShell

Question

I am trying to use the method DetachBuffer() of Windows.Storage.Streams.DataWriter but PowerShell only recognizes the IBuffer that it supposed to return as __ComObject. I have used other WinRT objects successfully, but this one is giving me trouble.

[void][Windows.Storage.Streams.DataWriter, Windows.Storage.Streams, ContentType = WindowsRuntime]
$dataWriter = [Windows.Storage.Streams.DataWriter]::new()
$dataWriter.WriteByte(0x01)
$buffer = $dataWriter.DetachBuffer()
$buffer

System.__ComObject

$buffer | Get-Member


   TypeName: System.__ComObject

Name                      MemberType Definition
----                      ---------- ----------
CreateObjRef              Method     System.Runtime.Remoting.ObjRef CreateObjRef(type requestedType)
Equals                    Method     bool Equals(System.Object obj)
GetHashCode               Method     int GetHashCode()
GetLifetimeService        Method     System.Object GetLifetimeService()
GetType                   Method     type GetType()
InitializeLifetimeService Method     System.Object InitializeLifetimeService()
ToString                  Method     string ToString() 

I am assuming that I need to "import" some WinRT class that DetachBuffer() is actually returning, but I have no clue what it is other than it implements IBuffer interface.

Answer 1

In my search for an answer to a similar problem (IInputStream Interface) I came upon this Reddit thread that gets the content of IBuffer as follows:

[System.Runtime.InteropServices.WindowsRuntime.WindowsRuntimeBufferExtensions].
GetMethod(
    'ToArray',
    [type[]]@([Windows.Storage.Streams.IBuffer])).
Invoke($null, @($buffer))

From your question it is unclear what you want to achieve, but let me know if this helps. If not, please amend the question so that it is clear what you want to do with the IBuffer.

As the commenter below correctly adds: PowerShell does not work with WinRT object that have no concrete type (in this case IBuffer Interface). I've been using .Invoke() to work around that, but in my very limited experience it's a hassle and not always gives you what you really need.