A Programmer's Introduction to Visual Basic® .NET

Cross-Language Interoperability

If you've been building COM components for a while, you know that one of the great promises of COM is that it is language independent. If you build a COM component in C++, you can call it from VB, and vice versa. However, to reach that point, your code had to be compiled to a COM standard. Much of this was hidden from the VB developer, but your component had to implement the IUnknown and IDispatch interfaces. Without these interfaces, it would not have been a true COM component. COM is only giving you cross-language interoperability at the binary level, however. This means that you can only take advantage of this interoperability at run time.

Now, however, the CLR gives you much better language interoperability. ...