Examples of using Marshal.GetTypedObjectForIUnknown()?

[Valery Polyakov]

Hi, does anyone has examples or code snippets showing
usage of GetTypedObjectForIUnknown() to get a COM object
of a desired type form its IUnknown pointer?

Thanks

[NETMaster]

Here it is:
- Let's create an object by known ProgID,
- query it's IUnknown,
- clone this IU back to the object by using GetTypedObjectForIUnknown,
- and free/Release all

// ------------------------------ (c) NETMaster ;-) ------------
// activate object of any COM-server via ProgID:
Type srvtype = Type.GetTypeFromProgID( "customize here: Vendor.ProgID" );
object actobj = Activator.CreateInstance( srvtype );

// query the IUnknown-pointer for this object (does internal AddRef!)
IntPtr iuptr = Marshal.GetIUnknownForObject( actobj );

// now clone this IUnknown-pointer back to the object..
object sameobj = Marshal.GetTypedObjectForIUnknown( iuptr, srvtype );

// reverse the GetIUnknownForObject
Marshal.Release( iuptr );
iuptr = IntPtr.Zero;

// free the clone
sameobj = null;

// free the origin
Marshal.ReleaseComObject( actobj );
actobj = null;
// -------------------------------------------

Ok?

"Valery Polyakov" <valery....@writeme.com> wrote in message news:840301c137b5$3cca8c80$19ef2ecf@tkmsftngxa01...

[Valery Polyakov]

Thanks for your reply.

Now a question is: can you instead of

object sameobj = Marshal.GetTypedObjectForIUnknown( iuptr, srvtype );

have that "sameobj" to be of a desired type, corresponding to srvtype, noting that this type was already imported
through tlbimp and is known in the application namespace.

something like:

myCOMtype sameobj = Marshal.GetTypedObjectForIUnknown( iuptr, srvtype );

this would allow be to get the advantages of early binding in the application.

Thanks again

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[NETMaster]

sure, use typeof() and casting:
myCOMtype sameobj = (myCOMtype) Marshal.GetTypedObjectForIUnknown( iuptr, typeof( myCOMtype) );

Please use specific newsgroup:
microsoft.public.dotnet.framework.interop
for more help...

"Valery Polyakov" <valery....@writeme.com> wrote in message news:#JfayA8NBHA.1692@tkmsftngp04...

[Valery Polyakov]

Thanks,

But, in my case this throws a InvalidCastException during runtime. Do you know how to avoid it?

Valery

[NETMaster]

Ah, I see...
If you do TLB-import/reference a component, you have a
'managed wrapper class type',
and not a plain 'COM object'...

try this two steps :

// convert IUnknown-pointer to temporary COM-object
object iuobj = Marshal.GetObjectForIUnknown( iuptr );

// convert COM-object to wrapper-object
myCOMtype wrpobj = (myCOMtype) Marshal.CreateWrapperOfType( iuobj, typeof( myCOMtype ));

// free temporary COM-object
iuobj = null;

note, it depends on how you got the IUnknown-pointer and
if the types are compatible...

"Valery Polyakov" <valery....@writeme.com> wrote in message news:Otc7Dr8NBHA.1880@tkmsftngp05...

>
> myCOMtype sameobj = Marshal.GetTypedObjectForIUnknown( iuptr, srvtype );

[Alexander Shaburov]

Hi, NETmaster.

You know as run COM-server, but how can I release Word or OUTLOOK from
memory in this VB6 code?

All 'nothing' don't work in this code.

Thank you for advise. Alex

=============VB6

Sub Main()

Dim an As New NetTest7.IClassMain

Dim wa As New Word.Application

an.Init_Class2 wa

Set an = Nothing

Set wa = Nothing

End Sub

============VC#

using System;

using System.Windows.Forms;

using System.Runtime.InteropServices; // For COMException

namespace NetTest7

{

public interface IClassMain

{

void Init_Class2(ref Word.Application wa);

}

public class ClassMain : IClassMain

{

public ClassMain()

{

MessageBox.Show("Create");

}

public void Init_Class2(ref Word.Application wa)

{

Word.Application wa1;

wa1 = (Word.Application )Marshal.CreateWrapperOfType( wa ,
typeof(Word.Application ) );

}

}

}

"NETMaster" <spam.ne...@swissonline.ch> wrote in message
news:e2u3fu9NBHA.1432@tkmsftngp03...