Delphi 7 not generating COM classes when importing Type Library

Question

In C#, I have a class and its interface in my solution, and I want them to be COM visible.

I have:

1. created the interface and the class as following:

   [InterfaceType(ComInterfaceType.InterfaceIsDual), Guid("0D1ABB24-144E-4C88-A4A5-DC3ED0E61BEB")]
   [ComVisible(true)]
   public interface IMyInterface
   {
       // methods here
   }
   
   [ClassInterface(ClassInterfaceType.None), Guid("01AA5822-83D1-42C6-A578-C9A84AB836AA")]
   [ComVisible(true)]
   public class MyClass : IMyInterface
   {
       // implementation here
   }
   

   (note they are both COM visible)

2. generated a GUID and informed it in the Assembly Info:

   [assembly: Guid("MY-GUID-HERE")]
   

3. Registered it with this command line:

   c:\regasm.exe /tlb MyAssembly.Dll
   

4. Imported the Type Library in Delphi 7.

A unit is generated, but it does not contain the class and functions/procedures. Calling CoClass.Create returned a "Class not registered" error.

Later I created a new solution with a class library, performing the same operations above, and the classes/methods where generated and I could access them.

Are there any tips about what I might have missed?

Answer 1

I found out the difference. One TLB class I wanted to export had some constructors in a region. When I expanded it, I saw there was no overloaded constructor without parameters. After adding a no-argument constructor, it was visible at Delphi and I could use it normally.