Importing interfaces in IDL from an external type library

Question

I have two type libraries with COM interfaces that I wrote using ATL and Microsoft's IDL. I would like an interface in one library to inherit from an interface in the other.

Essentially, I would like to do the same thing that Steven described at How do I create interface methods using .tlb types in VS C++?. The only person who answered him did not seem to understand the question.

Here's what I'd like to do, in code:

---

SomeLibrary DLL/TLB

ISomeInterface.idl

interface ISomeInterface : IDispatch { ... };

SomeLibrary.idl

import "ISomeInterface.idl";

library SomeLibrary
{
    interface ISomeInterface;
};

---

SomeOtherLibrary DLL/TLB

ISomeOtherInterface.idl

// What do I put here so that the MIDL compiler knows
// what to do when it encounters the ISomeInterface type?

interface ISomeOtherInterface : ISomeInterface { ... };

SomeOtherLibrary.idl

import "ISomeOtherInterface.idl";

library SomeOtherLibrary
{
    interface ISomeOtherInterface;
};

---

The MIDL import directive only works when importing IDL files, and I only have a DLL and TLB. I can't use importlib because that only works within a library definition. The MIDL compiler doesn't understand Microsoft's C++ import, importidl, and importlib attributes.

What to do?

Answer 1

If you are willing to introduce a manual step, you can open the tlb in oleview and get a generated .idl file that way. oleview.exe lives in the bin dir of the Windows SDK, eg

  C:\Program Files\Microsoft SDKs\Windows\v6.0A\bin\oleview.exe