ExcelDna 1.9.0-rc3: Issues with ParamArray in VB.NET UDFs
SJ Rhi
<PackageReference Include="ExcelDna.Interop" Version="15.0.1" />
<PackageReference Include="ExcelDna.Addin" Version="1.9.0-rc3" />
<PackageReference Include="ExcelDna.IntelliSense" Version="1.9.0-rc3" />
<PackageReference Include="ExcelDna.Registration" Version="1.9.0-rc3" />
<PackageReference Include="ExcelDna.Registration.VisualBasic" Version="1.9.0-rc3" />
<PackageReference Include="ExcelDna.XmlSchemas" Version="1.0.0" />
Function DnaAddValues(<ExcelArgument(Name:="Value1", Description:="value")> val1 As Double,
<ExcelArgument(Name:="Values", Description:="values")> ParamArray vals As Double()) As Double
Dim sum As Double = val1
If vals IsNot Nothing Then
For Each val As Double In vals
sum += val
Next
End If
Return sum
End Function
Govert van Drimmelen
The code you show should work, and does work right on my machine.
Is this the whole project, or perhaps embedded in an existing add-in where you are doing explicit registration processing in your AutoOpen()?
The new extended registration support works as long as you don’t have ‘ExplicitRegistration’ enabled in the project or .dna file (if you have a .dna file – you shouldn’t need one anymore – it’s auto-generated by the build).
You should be able to remove the two “ExcelDna.Registration****” packages, as well as “ExcelDna.Integration”.
Then for the IntelliSense to work you need something like this:
Imports ExcelDna.Integration
Imports ExcelDna.IntelliSense
Public Class MyAddIn
Implements IExcelAddIn
Public Sub AutoOpen() Implements IExcelAddIn.AutoOpen
IntelliSenseServer.Install()
End Sub
Public Sub AutoClose() Implements IExcelAddIn.AutoClose
IntelliSenseServer.Uninstall()
End Sub
End Class
I then get:
-Govert
From: exce...@googlegroups.com <exce...@googlegroups.com> On Behalf Of SJ Rhi
Sent: 17 July 2025 10:19
To: Excel-DNA <exce...@googlegroups.com>
Subject: [ExcelDna] ExcelDna 1.9.0-rc3: Issues with ParamArray in VB.NET UDFs
Hi Govert,
I'm experiencing some unexpected behavior with ParamArray when developing Excel UDFs using ExcelDna 1.9.0-rc3. I installed the NuGet packages and am trying to use a ParamArray as shown in the sample code below, but it doesn't seem to be working as expected.
1. When I enter a third argument (e.g., =DnaAddValues(1, 2, 3, 4) ), Excel treats it as a #VALUE! error, and this argument is not passed to the UDF.
2. The function only seems to work correctly when the second argument is explicitly an array (e.g., =DnaAddValues(1, {2, 3, 4}) )
3. IntelliSense doesn't display help for the third argument onwards, even though it should be part of the ParamArray.
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SJ Rhi
Thank you for the reply.
As you suggested, I removed the two Registration packages and the Integration package,
disabled the <ExplicitRegistration> option,
and finally removed the RegisterFunctions process.
I've confirmed that it's now working correctly.
I need to use multilingual descriptions for UDFs,
so I have to apply descriptions with RegisterFunctions depending on the language environment.
Is there a way to do this?
Govert van Drimmelen
You can add a public method like this to your add-in:
<ExcelFunctionProcessor>
Public Shared Iterator Function ApplyLocalisation(registration As IEnumerable(Of IExcelFunctionInfo), config As IExcelFunctionRegistrationConfiguration) As IEnumerable(Of IExcelFunctionInfo)
' This function can be used to apply localization to the functions.
' For example, you could modify the names or descriptions based on the user's locale.
For Each func As IExcelFunctionInfo In registration
Debug.Print($"Processing function: {func.FunctionAttribute.Name}")
func.FunctionAttribute.Description = "Localised" & func.FunctionAttribute.Description
For Each param As ExcelParameterRegistration In func.Parameters
param.ArgumentAttribute.Description = "Localised " & param.ArgumentAttribute.Description
Next
Yield func
Next
End Function
If will work for your `ParamArray` function, but at the moment won't work for your standard functions that don't get extra transformations applied.
So, a simple function like this one won't get processed through the function processor:
<ExcelFunction(Description: "Not Localised :-( ")>
Public Shared Function AddThem(d1 As Double, d2 As Double) As Double
Return d1 + d2
End Function
We're looking at it some more to get a better answer.
-Govert