Using early binding on a COM object

Question

I have this piece of code that works very well and gives me the path the user's start menu:

    Dim oShell As Object = CreateObject("Shell.Application")
    MsgBox(oShell.NameSpace(11).Self.Path)

This obviously uses late binding. Now say I want to do this in C#, or in VB.NET strict mode, neither of which support this kind of syntax with late binding.

Is this possible? How?

Thanks for you help!

Answer 1

If you want to solve this the COM way you have to figure out, which COM reference to add in your VB project.

Open regedit and navigate to HKEY_CLASSES_ROOT\<class id>\CLSID, i.e.

HKEY_CLASSES_ROOT\Shell.Application\CLSID

and you will find the class id which uniquely identifies the COM component.

Under HKEY_CLASSES_ROOT\CLSID you can now look up which file is behind the COM component:

HKEY_CLASSES_ROOT\CLSID\{13709620-C279-11CE-A49E-444553540000}\InProcServer32

shows the following value:

%SystemRoot%\system32\SHELL32.dll

Now go to Visual Studio, and add a reference to this file (on the Browse tab of the Add References dialog). If you open up the projects properties, you will actually see that the nice name of the COM component added is Microsoft Shell Controls and Automation.

Once the reference is added you can use the Shell.Application object as follows:

Option Strict On

Module PrintStartMenuLocation

    Sub Main()
        Dim shell As New Shell32.Shell
        Dim folder As Shell32.Folder
        Dim folderItem As Shell32.FolderItem
        Dim startMenuPath As String

        folder = shell.NameSpace(Shell32.ShellSpecialFolderConstants.ssfSTARTMENU)
        folderItem = CType(folder.Items(0), Shell32.FolderItem)
        startMenuPath = folderItem.Path

        Console.WriteLine(startMenuPath)
    End Sub

End Module

A version in C# would look as follows:

class Program
{
    static void Main(string[] args)
    {
        Shell32.Shell shell = new Shell32.Shell();
        Shell32.Folder folder = shell.NameSpace(Shell32.ShellSpecialFolderConstants.ssfSTARTMENU);
        Shell32.FolderItem folderItem = folder.Items().Item(0) as Shell32.FolderItem;
        string startMenuPath = folderItem.Path;

        Console.WriteLine(startMenuPath);
    }
}

However, if you simply need to retrieve the location of the Start Menu folder you can do the same directly in .NET using

Dim path As String = System.Environment.GetFolderPath(Environment.SpecialFolder.StartMenu)

Answer 2

If I remember correctly, all you have to do is to cast the object reference into the appropriate interface. If you use a COM object in .NET, you typically import the type library and then have the interfaces readily available.

Answer 3

Dim DirPath As String = _
    System.Environment.GetFolderPath(Environment.SpecialFolder.StartMenu)

See here for more.

Answer 4

Well actually you could use reflection:

Type shellType = Type.GetTypeFromProgID("Shell.Application", true);
object shell = Activator.CreateInstance(shellType);
object folder = shellType.InvokeMember("NameSpace", BindingFlags.InvokeMethod, null, shell, new object[] { 11 });
object self = folder.GetType().InvokeMember("Self", BindingFlags.GetProperty, null, folder, new object[] { });
object path = self.GetType().InvokeMember("Path", BindingFlags.GetProperty, null, self, new object[] { });
Console.WriteLine(path);

Not the kind of code I like, but in C# 4.0 you could use the dynamic type to clean up this mess.