[C#] COM Object から TypeInfoName を取得する

var type = Type.GetTypeFromProgID("Shell.Application");
var comObject = Activator.CreateInstance(type);
var name = MarshalUtil.GetTypeInfoName(comObject);

Console.WriteLine(name); // IShellDispatch6

using System.Runtime.InteropServices;
using System.Runtime.InteropServices.ComTypes;

public static class MarshalUtil
{
    public static string? GetTypeInfoName(object comObject)
    {
        if (comObject is not IDispatch dispatch)
            return null;

        var typeInfo = dispatch.GetTypeInfo(0, 0);
        return Marshal.GetTypeInfoName(typeInfo);
    }

    [ComImport]
    [Guid("00020400-0000-0000-C000-000000000046")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    private interface IDispatch
    {
        int GetTypeInfoCount();
        ITypeInfo GetTypeInfo(int iTInfo, int lcid);
    }
}

var typeInfo = dispatch.GetTypeInfo(0, 0);
typeInfo.GetDocumentation(-1, out var name, out var doc, out var helpContext, out var helpFile);

Console.WriteLine(name);        // IShellDispatch6
Console.WriteLine(doc);         // Updated IShellDispatch
Console.WriteLine(helpContext); // 0
Console.WriteLine(helpFile);    // null

var name = Microsoft.VisualBasic.Information.TypeName(comObject);

var dispatchPtr = Marshal.GetIDispatchForObject(comObject);
var typeInfoPtr = Marshal.GetITypeInfoForType(dispatchPtr.GetType());
var typeInfo = (ITypeInfo)Marshal.GetTypedObjectForIUnknown(typeInfoPtr, typeof(ITypeInfo));
var name = Marshal.GetTypeInfoName(typeInfo);