iunknown

what's your opinion on IUnknown?

http://en.wikipedia.org/wiki/IUnknown
http://en.wikipedia.org/wiki/Component_Object_Model

Would you choose to use such an interface/design yourself?

>>2,3

Yeah, I have only seen it used in a few times. I find it interesting though. If I was to implement arbitrary interfaces in C, I might have tried an implementation similar to iunknown, where one would query an object with an interface id, and then get back a structure of function pointers that implement the interface for that object. But I've seen IUnknown reinvented and used in applications that are nothing but seeples, and I don't understand why someone wouldn't just rely on oo provided through the language in such a case.