[boost] Re: Empty member optimization

David Abrahams wrote:

I think the question is whether it's ever desirable to break the current C++ invariant that no two objects of the same type will ever share an address **in generic code** -- that is, when you don't know anything about the assumptions that may be made by that type.

An alternative implementation is to privately inherit from the specified type for empty classes as compressed_pair does. This maintains the invariant but has the drawback that inheritance is visible in user code. For a generic compressed_tuple the private inheritance should not be a problem. João