Expose dll for COM Interop

Question

I thought I knew how to do this, but obviously not so I'd appreciate some help! I can't get my dll to register so I can instantiate it in a VBS, or elsewhere.

I wrote the following sample class, checked "Make assembly COM Visible", checked "Register for COM Interop", then built it. When I try to instantiate it from VBS I get the "Activex component can't create object" error.

This is the class code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Smurf
{
    public class Pants
    {
        public string Explode(bool Loud)
        {
            string result;
            if (Loud)
                result = "BANG";
            else
                result = "pop";
            return result;
        }
    }
}

...and this is the VBS:

Dim a

Set a = CreateObject("Smurf.Pants")

msgbox("ok")

What else do I need to do?

Thanks :)

[edit]

Forgot to mention, after the first failure I tried REGSVR32 and REGASM - no help!

[/edit]

Note that when I try REGSVR32, I get this message:

The Module "C:...\Smurf.dll" was loaded but the entry-point DllRegisterServer was not found. Make sure that "C:...\Smurf.dll" is a valid DLL or OCX file and then try again.

How helpful is that??

This is the latest version of the code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;

namespace Smurf
{
    [Guid("EAA4976A-45C3-4BC5-BC0B-E474F4C3C83F")]
    public interface IPants
    {
        [DispId(1)]
        string Explode(bool Loud);
    }

    [Guid("7BD20046-DF8C-44A6-8F6B-687FAA26FA71"),
        InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]
    public interface IPantsEvents
    {
        string Explode(bool Loud);
    }

    [ComVisible(true)]
    [Guid("0D53A3E8-E51A-49C7-944E-E72A2064F938"),
        ClassInterface(ClassInterfaceType.None),
        ComSourceInterfaces(typeof(IPantsEvents))]
    public class Pants : IPants
    {
        public Pants() { }

        [ComVisible(true)]
        [ComRegisterFunction()]
        public static void DllRegisterServer(string key) { }
        [ComVisible(true)]
        [ComUnregisterFunction()]
        public static void DllUnregisterServer(string key) { }

        [ComVisible(true)]
        public string Explode(bool Loud)
        {
            string result;
            if (Loud)
                result = "BANG";
            else
                result = "pop";
            return result;
        }
    }
}

Answer 1

There could be a few different things at play here. First, you'll want to use the regasm tool with the /codebase /tlb switch from an elevated command prompt (assuming Windows Vista, 7 or Windows Server 2008). Something like:

regasm "Path to Smurf.dll" /codebase /tlb

Once you have registered the dll using regasm you should be able to invoke it using VBS, VBA or VB6.

I was able to use early binding and late binding from VBA to call the Explode method. However, when I tried from VBScript I received the "ActiveX can't create object error as you did."

I'm running on Windows 7 64 bit, and I recalled that this can cause problems when compiling to 32 bit dlls and running them on 64 bit operating systems. On a whim, I fired up a command prompt and entered:

C:\Windows\SysWow64\CScript.exe "Path to VBScript"

The result was that the script ran correctly and displayed "Pop" on screen.

Here's the somewhat simplified C# code I used as well as the contents of the VBScript file.

namespace Smurf
{
    [Guid("EAA4976A-45C3-4BC5-BC0B-E474F4C3C83F")]
    public interface IPants
    {
        string Explode(bool Loud);
    }

    [Guid("7BD20046-DF8C-44A6-8F6B-687FAA26FA71"),
     InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]
    public interface IPantsEvents
    {
        string Explode(bool Loud);
    }

    [ComVisible(true)]
    [Guid("0D53A3E8-E51A-49C7-944E-E72A2064F938")]
    [ClassInterface(ClassInterfaceType.None)]
    [ComSourceInterfaces(typeof(IPantsEvents))]
    public class Pants : IPants
    {

        [ComVisible(true)]
        public string Explode(bool Loud)
        {
            string result;
            if (Loud)
                result = "BANG";
            else
                result = "pop";
            return result;
        }
    }
}

VBScript:

Dim x 
Set x = CreateObject("Smurf.Pants")
MsgBox (x.Explode(False))
Set x = Nothing