.net - COM interop interface casting -

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following this article, have translated c++ com class/interface declaration c# this:

[interfacetype(cominterfacetype.interfaceisiunknown), guid(ifaceguid)] public interface ifoo {   void bar(); }  [comimport, guid(classguid)] public class foo { }

i use this:

var foo = new foo(); var ifoo = (ifoo)foo;  ifoo.bar();

my question is, how can possibly work, considering foo doesn't implement ifoo (even @ runtime, typeof(foo).getinterfaces() empty) , user-defined conversions interfaces forbidden?

is special handling reserved com? c# specification have this?

comimport types treated differently compared "normal" .net classes, constitute runtime-callable wrapper around underlying com coclass. casting instance of 1 of these com interface type transparently mapped call object's implementation of com interface method iunknown.queryinterface.

if qi requested interface succeeds @ com level, c# cast succeed.


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