Easy way to make a com DLL in c#?

Easy way:
1) run Visual Studio (I am using 2003 .Net)
2) File - new - project
3) Visual C# - Windows Control Library (or Class Library), enter the name
4) Define what you need to do (all methods you want to public must be defined as public...)
5) use

	[ClassInterface(ClassInterfaceType.AutoDual)]

before your class definition
(using System.Runtime.InteropServices;)
6) Open properties for your project, Configuration properties - Register For COM interop = true
7) Build the project
8) use it in Navision...

Because I am begginer in C#, I do not know how to "public" something through inheritance (to not need define each function I want to public once more...)

Thank you for the answer, but I find my answer in Navision 4.00 Development II chapter 9, where it says "However, Microsoft Navision only supports non-visual controls".

So, then there`s no point in using Windows Control Library, you can just use Control Library, since "Windows Control Library" can`t be added or shown anyhow in Navision.

Yes, I am solving same thing in Visual Studio 2005 now. What I found yet is, that the DualInterface is not recommanded. But I do not know, how to do it without this... If I do not use this, I do not see the functions and properties in Navision... (and I do not want to use external tools)...

Here is an C# example of how to code a .Net dll that is available to Navision, without exposing all of the default Com methods.

This example will expose just one property: HelloWorld()

using System;
using System.Runtime.InteropServices;

namespace WhatEver
{
	
  public interface IMyClassInterface
  {
    [DispId(1)]
      string HelloWorld {get;}
  }

  [ClassInterface(ClassInterfaceType.None)]
  [GuidAttribute("E0A33D6F-FCD2-4e85-9A2D-1A908EC39598")]
  public class MyClass : IMyClassInterface
  {
    public MyClass() {}

    public string HelloWorld
    {
      get
      {
        return("Hello World!");
      }
    }
  }
}

Yes, the fixed DispId is the key factor here.

My thoughts about this: Navision is not capable of using late binding. For that reason you have to know the DispId at designtime. Specifying the DispId in your interface makes the DispId fixed, so Navision is able to store the correct DispId during compilation and use it runtime.

By default, the interfaces used by a .NET Class are transformed to dual interfaces in the IDL. This allows the client to get the best of both early binding and late binding. However, there may be occasions when you want the interface to be a pure-dispinterface or a custom IUnknown only based interface. You can override the default type of the interface using the InterfaceTypeAttribute.
To have the Interface hidden for Navision you have to specify that the Interface is type IUnknown.
By using

<InterfaceType(ComInterfaceType.InterfaceIsIUnknown)> _
Interface MyInterface

However, this will hide the interface information of the methods and properties. If you try this you will see that Navision is not able to determine the return type of the methods and instead is using something like

HRESULT = Property(VARIANT parameter)

The other option is to specify your Class as DualInterface. Because every .Net class derives the base interface from the _Object interface, you will see that the Equals, ToString and GetHash methods are specified, along with your interface methods.

Still have problem with visibility of the functions and properties...
I am using VS 2005.

Example of my code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Text;
using System.Windows.Forms;
using System.Reflection;
using System.Runtime.InteropServices;

namespace MyWrapper2005
{
    [GuidAttribute("MyIFGUID")]
    interface IWrapperClass
    {
        [DispId(1)]
        string Property1 { get; set; }
        [DispId(2)]
        public void Function1(string x, string y, short zoom);
    }

    [ClassInterface(ClassInterfaceType.None)]
    [GuidAttribute("myGUID")]
    public partial class WrapperClass : Form, IWrapperClass
    {
        public string Property1        {
            get
            {
                return Component.Property1;
            }
            set
            {
                Component.Property1 = value;
            }
        }
        public void Function1(string x, string y, short zoom)
        {
            Component.Function1(x, y, zoom);
        }
    }
}

But still I am not able to see the properties (I see only the class in Navision, not the interface). I am using StrongName for the class...

I have "Make assembly COM-visible = true" in Project property, "Register for COM interop = true".

Have someone tip where can be the problem?

The class is wrapper for one Automation, which I am opening in new window (it is why the class is inherited from Form class) and on this form I placed visual component "Component".
When I use ClassInterfaceType.AutoDual, I can use the class without problems (but I see all the functions and properties from _Object)...

Added, without success... :-/

How can I unregister the .net interop DLL? (I know only the way of regsvr32 but this is not the correct one in this case)