IEnumerable.GetEnumerator() returns IEnumVariant in Delphi 6

Question

I am using a .Net2.0 Assembly in Delphi 6 via COM. One of the methods in one of the interfaces returns IEnumerable. As long as I import mscorlib.tlb located in

"C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727"

, I can reach both IEnumerable and IEnumerator interfaces in Delphi 6. Here is the part where IEnumerable is defined in mscorlib_TLB.pas:

// *********************************************************************//
// Interface: IEnumerable
// Flags:     (4416) Dual OleAutomation Dispatchable
// GUID:      {496B0ABE-CDEE-11D3-88E8-00902754C43A}
// *********************************************************************//
  IEnumerable = interface(IDispatch)
    ['{496B0ABE-CDEE-11D3-88E8-00902754C43A}']
    function GetEnumerator: IEnumVARIANT; safecall;
  end;

The return value of the GetEnumerator method is not IEnumerator and when I try to cast it to IEnumerator 'Interface not supported' exception is thrown.

Has anyone encountered this or a similar problem before? How can it be resolved?

Answer 1

This is standard behavior when interacting with .NET objects through COM interop, as specified here:

http://msdn.microsoft.com/en-us/library/111chfb8(VS.71).aspx

Answer 2

A link to MSDN's explanation of the IEnumVARIANT may also be valuable: http://msdn.microsoft.com/en-us/library/ms221053.aspx