Skip to Main Content
C# in a Nutshell
book

C# in a Nutshell

by Ben Albahari, Ted Neward, Peter Drayton
March 2002
Intermediate to advanced content levelIntermediate to advanced
864 pages
31h 8m
English
O'Reilly Media, Inc.
Content preview from C# in a Nutshell

Exposing COM Objects to C#

When you instantiate a COM object you are actually working with a proxy known as the Runtime Callable Wrapper (RCW). The RCW is responsible for managing the lifetime requirements of the COM object and translating the methods called on it into the appropriate calls on the COM object. When the garbage collector finalizes the RCW, it releases all references to the object it was holding. For situations in which you need to release the COM object without waiting for the garbage collector to finalize the RCW, you can use the static ReleaseComObject method of the System.Runtime.InteropServices.Marshal type.

The following example demonstrates how to change your MSN Instant Messenger friendly name using C# via COM Interop:

// RenameMe.cs - compile with:
//   csc RenameMe.cs /r:Messenger.dll
// Run RenameMe.exe "new name" to change your name
//   as it is displayed to other users.
// Run TlbImp.exe "C:\Program Files\Messenger\msmsgs.exe"
//   to create Messenger.dll
using System;
using Messenger;
class MSNFun {
    static void Main(string[] args) {
        MsgrObject mo = new MsgrObject();
        IMsgrService ims = mo.Services.PrimaryService;
        ims.FriendlyName = args[0];
    }
}

You can also work with COM objects using the reflection API. This is more cumbersome than using TlbImp.exe, but is handy in cases in which it’s impossible or inconvenient to run TlbImp.exe. To use COM through reflection, you have to get a Type from Type.GetTypeFromProgID() for each COM type you want to work with. Then, ...

Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Start your free trial

You might also like

C# 8.0 in a Nutshell

C# 8.0 in a Nutshell

Joseph Albahari, Eric Johannsen
C# 10 in a Nutshell

C# 10 in a Nutshell

Joseph Albahari
C# in a Nutshell, Second Edition

C# in a Nutshell, Second Edition

Peter Drayton, Ben Albahari, Ted Neward
Code like a Pro in C#

Code like a Pro in C#

Jort Rodenburg

Publisher Resources

ISBN: 0596001819Catalog PageErrata