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Exposing .Net Methods To VBA (COM)

Posted on 2013-06-29
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Last Modified: 2013-09-10
I am currently in the process of extending my Excel VBA project using VB.Net and Visual Studio. I’ve created a working DLL, made it COM visible and registered, and referenced it from my Excel file.
      In my DLL, I have created a few classes (each with its own interface and explicit GUID to prevent errors caused by adding/removing methods/properties). I have successfully used these classes in VBA in this way:

Dim abc As New MyClass
abc.MyMethod

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      The problem is that I have a few subs that I am trying to use that aren’t part of any class. These are in a module call “Misc”, as shown below:

Public Module Misc
	Public Sub MySub()

	End Sub
End Module

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      I want to be able to call these from VBA, either by just saying:
Call MySub

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Or
Call MyNamespace.MySub

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     But when I try to call the sub, it can’t find it and I get “sub or function not defined”.
The only way I’ve been able to access the sub is to write a class and interface that simply calls that sub, but that seems like a lot of work just to call one sub, plus I also have to create a new instance of the class in VBA before I can call the sub, adding an extra line of code.
      Is there any way around this?
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Question by:BROOKLYN1950
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7 Comments
 
LVL 83

Expert Comment

by:CodeCruiser
ID: 39287280
Does following work?

Call Misc.MySub
0
 
LVL 16

Expert Comment

by:Easwaran Paramasivam
ID: 39287853
There is an option. Change the module to NonInheritable (static) class and method as Shared (static) method. So that it could be called as Module.Method without more code changes.

http://stackoverflow.com/questions/436605/vb-net-how-to-reference-vb-net-module


HTH.
0
 

Author Comment

by:BROOKLYN1950
ID: 39288943
I tried both your suggestions. I can't believe I didn't think of CodeCruiser's suggestion, but just as well I guess, 'cause unfortunately it doesn't work. As for EaswaranP's suggestion, I changed:

Public Module Misc

      Public Sub MySub

      ...

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to

Public NotInheritable Class Misc

      Public Shared Sub MySub

      ...

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      Unfortunately this didn't work either. I could not call the sub directly, no mater how explicitly I wrote it or how I used the "Call" statement. I could get the module (or class as it now is) to show up by saying:
Dim abc as MyNamespace.Misc

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But when I tried:
Dim abc as MyNamespace.Misc
abc.MySub

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I got an "object reference not set to instance of an object" error.

So no solution yet, but hopefully we're getting close.
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LVL 16

Expert Comment

by:Easwaran Paramasivam
ID: 39289127
You no need to declare using Dim. Just call the method as MyNamespace.Misc whenever you required. Thats it.
0
 

Author Comment

by:BROOKLYN1950
ID: 39290704
I tried that, as I said in my last reply,
I could not call the sub directly, no mater how explicitly I wrote it or how I used the "Call" statement.

I tried all of the below:
MySub
Misc.MySub
MyNamespace.Misc.MySub

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And I also tried each of those prefixed with the "Call" statement (though I don't  think that would make a difference).
0
 

Accepted Solution

by:
BROOKLYN1950 earned 0 total points
ID: 39467540
I pretty much forgot about this question until I stumbled on it today. I have figured out my own solution and though its far from optimal it was the only thing I found that worked the way I needed it to.

I created a standard class with an explicit GUID and an explicit interface with en explicit GUID. This class has members named after the the ones in my module (static class). The members in the normal class call the members in the module.

The non-static class is exposed to COM the same was as my other non-static classes and I can call the members of my module through this class. At the same time, my VB.Net code can call the members straight from the module without need to create an instance of a class to use.

So in short, COM sees a non-static class, and .Net sees both a static call and a non-static class which has calls to the static class.

The downside to this is that I have to declare each of my members three times, which can get annoying, but at least it works!
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Author Closing Comment

by:BROOKLYN1950
ID: 39479072
I figured out my own solution as explained in the answer
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