can any interface inheriting IUnknown be made into a COM interface?

问题

I need to call methods of the IWeatherStation interface which inherits IUnknown from C#. How do I go about it, if it is possible?

Thank you

回答1:

Sure. There is an example here: Example COM Class (C# Programming Guide).

The first thing you should do is locate the real (idl or c/c++) definition of the interface. For this SDK it's located for example in the <setup path>\Lockheed Martin\Prepar3D v4 SDK 4.3.29.25520\inc\PDK\IWeatherSystem.h header file. This is where you will get the methods and the interface id (a.k.a. 'IID').

So in your case, it would be something like:

[Guid("e4452b96-16ba-4e82-9342-aa37af1f5c26")] // IID
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
public interface IWeatherStationV430 // IUnknown base interface is implicit
{
    bool IsValid();
    float GetSurfaceWind();
    void SetSurfaceWind(float aVal);
    // etc...
}

来源：https://stackoverflow.com/questions/52425122/can-any-interface-inheriting-iunknown-be-made-into-a-com-interface