Why do I get a QueryInterface(IID_IMarshal) and then nothing?

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Jack Mathews says:

February 20, 2004 at 9:59 am

COM sometimes makes me want to cry.

Lonnie McCullough says:

February 20, 2004 at 12:29 pm

I have a question I have always wondered about. Say you have several objects that all aggregate the free threaded marshaler (and of course abide by the rules of doing so…no non free threded object references being held and whatnot). Is there any benefit to making the class object for those objects also aggregate the free threaded marshaler? Is this even safe (don’t see why it wouldn’t be on first inspection)?

Raymond Chen says:

February 20, 2004 at 12:37 pm

Sorry, I’m not an expert on COM marshalling. Maybe there’s a COM blogger you can ask.

Mike Dunn says:

February 20, 2004 at 3:27 pm

I always had the impression that you had to implement IMarshal only if you wanted to use your own custom marshaling. If you didn’t respond to a QI for IMarshal, you would get the default marshaling from COM (using the type library, for instance).

February 20, 2004 at 3:34 pm

This assumes that the interface COM is trying to marshal has a registered type library in the first place.

February 24, 2004 at 8:05 am

Unfortunately COM is so 2001 and your the only guy I know of that has even mentioned an IID in the past couple weeks.

Anonymous says:

February 25, 2004 at 8:50 am

I had this problem with some CE ActiveX controls originally developed for Pocket PC, when running them on a custom platform (PDT7200, if memory serves)….

The Old New Thing says:

December 13, 2004 at 11:51 am

It’s the other half of the missing IMarshal.

Date:	February 20, 2004 / year-entry #70
Tags:	code
Orig Link:	https://blogs.msdn.microsoft.com/oldnewthing/20040220-00/?p=40533
Comments:	8
Summary:	A common problem when trying to get your new COM object off the ground is that you can't seem to be able to get it created. The object comes out of the class factory, and it gets a QueryInterface for IMarshal, and then nothing. What's going on? This is a sure sign that you didn't...