COM Objects on Windows 7 with 4.7.2

[kwire]

schnitzel,

I downloaded and installed VB express. Tried it on the DYMO .NET VB example included in the SDK. After it converted the project it compiled it and ran just fine. I was able to open the label, fill in the data fields and it printed my labels including the barcode. So I guess the COM objects are registered and working OK.

I still can't think of a good reason I have to take the COM object instantiation out of the constructor. This project has a Main Form where I call each job from the menu by creating another form where I do the work and print my labels. Something in Qt must need to be done in the constructor before I can create these two COM objects.

I hate it when I don't know what is going on...

Keith

high_flyer,

I may be wrong, but I thought COM objects were reference counted and didn't need to be manually deleted. At least that is the way they always worked in Delphi and C#. When the last variable went out of scope that referenced the COM object the object was automatically deleted.

Is that not true for Qt?

Keith

[schnitzel]

Do they provide a C++ example? If so, are they also allocating the objects using new in the constructor?

[kwire]

schnitzel,

They have a Visual C++ example but they use CreateDispatch().

I took my inspiration for my code from the Qt dumpcpp documentation I found here.

I have tried lots of things and read lots and I think my usage is correct, it just won't work in the constructor of the form...

Keith

[high_flyer]

I may be wrong, but I thought COM objects were reference counted and didn't need to be manually deleted. At least that is the way they always worked in Delphi and C#. When the last variable went out of scope that referenced the COM object the object was automatically deleted.

Is that not true for Qt?

It has nothing to do with Qt.
Regarding the reference count on COM objects, I think it depends on what kind of pointer container they are held.
CComXXX<T> pointer does ref counts, but a plain pointer does not.
I can't see the declaration of the pointer variable so I don't know for your case.

You should run you application through a leak detection tool, which can also detect COM leakages to be sure.
I'd recommend that you ask that on a COM oriented forum, where the people know these issues in more detail.

[kwire]

high_flier, can you recommend a good "leak detection tool" that works on Windows 7?

[high_flyer]

You need more the just a leak detection tool, you need one that can also detect COM leaks (which (can be)/is trickier).
For "regular" leak detection you can use the CRT leak detection tool:
http://msdn.microsoft.com/en-us/libr...=vs.71%29.aspx
In my company we use our own brewed leak detection (which basically intercepts ALL (external as well) allocations/frees before the kernel) since we didn't find anything that could handle our large code base.
Again, you should ask that on forums that specialize with COM.