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Get rid of COM Interop DLL by using the new C# 4 dynamic keyword

, 7 Jan 2011 CPOL
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How to instantiate a COM object wrapper and call a method at runtime

Up to now, to call a COM object from managed code, you had to either:

  • make a reference to the COM instance from your Visual Studio project (which means you had to have the COM object setup on your development machine)
  • or make a reference to a precompiled assembly containing your COM interop wrapper

With the new framework .NET and C# 4 comes the dynamic keyword that allows binding to an object's method at runtime using the underlying DLR.

So to make thing short, the only thing you've got to do to interop with a COM object is to instantiate it using an activator as a dynamic variable and call a runtime bound method on it, in two lines:

dynamic comInterop= Activator.CreateInstance(Type.GetTypeFromProgID("MyCOM.Object.Name"));
var result = comInterop.MethodCall(parameter);

Hope this helps! Smile | :)


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Philippe Bouteleux
Software Developer (Senior)
France France
A happy .NET developper, fond of all the new bits of technologies M$ has to offer.

I code in C# using WPF, Linq, WCF and SQL Server all day long and I'm paied for that Smile | :)

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Comments and Discussions

QuestionInconsistent crashes in C# application which uses COM interop Pin
AmodVKulkarni14-Jun-12 2:51
memberAmodVKulkarni14-Jun-12 2:51 
Hi Philippe,

I have an addin written in C# which runs inside Microsoft Project. This addin inturn uses COM API of another application (our own product which exposes COM API to communicate with its database). The target framework is .NET 4.0.

Most of the times the functionality of addin works fine. But sometimes (very unpredictable) we found that COM API does not get called when they are expected to get called. We confirmed that by putting log information inside API implementation. This log does not get generated when we face this issue. The still bad part is that addin gets crashed when this error situation occurs.

I have two points.

1) Is there any known issue with COM interoperability in .NET which can result into such inconsistent behavior?

2) Do you think your suggestion of using dynamic keyword and eleminating interop dll can improve the things. If yes, we might think of refactoring our code.

Thanks in advance for your reply.
AnswerRe: Inconsistent crashes in C# application which uses COM interop Pin
Philippe Bouteleux14-Jun-12 4:25
memberPhilippe Bouteleux14-Jun-12 4:25 
QuestionObject Required Pin
ttflim21-Apr-12 14:15
memberttflim21-Apr-12 14:15 
AnswerRe: Object Required Pin
Philippe Bouteleux14-Jun-12 4:31
memberPhilippe Bouteleux14-Jun-12 4:31 

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