Why can't a Visual C++ interface contain operators?

Question

As per the MSDN doc on __interface, a Visual C++ interface "Cannot contain constructors, destructors, or operators."

Why can't an interface contain an operator? Is there that much of a difference between a get method that returns a reference:

SomeType& Get(WORD wIndex);

and the overloaded indexer operator?

SomeType& operator[](WORD wIndex);

Answer 1

The __interface modifier is a Visual C++ extension to help implementing COM interfaces. This allows you to specify a COM 'interface' and enforces the COM interface rules.

And because COM is a C compatible definition, you cannot have operators, Ctor or Dtors.