Shared object cannot be accessed in ExcelFunction

[Johnny24]

Hello,

maybe it's my fault, but I cannot understand the logic behing this.

I built an empty project with Excel-DNA, and I have a shared (static) object in a class named ThisAddIn.

Public Shared MyObj as Object

    Private Sub ThisAddIn_Startup() Handles Me.Startup
        MyObj = new MyObjClass() ' from external library
    End Sub

Everything works fine, except accessing the object from Excel function. For instance:

    <ExcelFunction(Name:="MyStrFunc", Description:="Return a property of MyObj")>
    Public Shared Function  MyStrFunc() As String
        Return MyObj.myProperty' here MyObj is nothing
    End Function

I also tried:

    <ExcelFunction(Name:="MyStrFunc", Description:="Return a property of MyObj")>
    Public Shared Function  MyStrFunc() As String
        Return Globals.ThisAddIn.MyObj.myProperty ' again, MyObj  is nothing
    End Function

What am I doing wrong? I'd expected that MyObj would be available even in  ExcelFunctions. In other parts of the code it's all fine, only ExcelFunctions are not working.

thanks in advance,

Giovanni

[Govert van Drimmelen]

Hi Giovanni,

 

You seem to be mixing a VSTO add-in (ThisAddIn etc.) and an Excel-DNA add-in into the same library.

This does not work well.

 

What is possibly happening in this case is that your code is loaded as a VSTO add-in into one AppDomain, and running code like ThisAddIn_Startup.

Then the code is loaded a second time as an Excel-DNA add-in, into a different AppDomain, and your functions registered and run in this AppDomain.

Shared objects are not ‘shared’ between AppDomains.

 

My suggestion is to neve mix VSTO (anything Microsoft.Office.Tools.*) and Excel-DNA in this same project.

 

Nearly all functionality from VSTO is available from the Excel-DNA add-in, though sometimes you have to do a little bit more work.

Is there a specific reason you are making this a VSTO add-in?

 

-Govert

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[Johnny24]

Yes, I mixed VSTO and Excel-DNA just to have visual design of ribbon bar. I suspected this would be the problem, but not sure before your reply (I was thinking  the AppDomain was unique). I'll have a closer look to the ribbon management in Excel-DNA, initially the XML for the ribbon discouraged me.

thanks,

Giovanni