----- Original Message ----- From: "Jonathan Turkanis" <technews@kangaroologic.com> To: <boost@lists.boost.org> Sent: Friday, January 28, 2005 6:00 PM Subject: [boost] Re: BIL and boost::any
One can think of smart references as generalizations of any in which
- the ownership policy can vary; e.g., it could be reference-counted instead of clone-on-copy - the type of admissible objects can restricted using interfaces - the syntax for binding is slightly different
For instance, a reference-counted any that can bind to anything is shared_obj<IAnything>.
Would it be a reasonable request then to have clone(interface_value)? Would make sense to also have dynamic traits, i.e. is_clonesable(interface_value). This seems to be pointing down a path of never ending feature requests to interface. I think it would be nice to lay down an easily extendible interface type. I mentioned earlier about allowing users to extend interface types. One way which I would like to extend interface types is to have an interface type which provides an extra function: Usage: dynamic_traits traits = extract_traits(interface_value); dyanmic_traits could be a class which provides run-time functions like: is_copy_constructible(); is_default_constructible(); size_of(); is_primitive(); is_integral(); etc.
I'm thinking of adding a template boost::interfaces::any, which has cloning semantics and uses the same syntax as any for binding, i.e., assignment and construction from a const reference.
template<typename Interface = IAnything> class any;
(I think boost::interfaces::null might be a better name for IAnything.)
How about IUnknown? It will be especially meaningful when boost::interfaces allow dynamic introspection.
However, maybe what is needed instead is just a policy-based smart reference.
That would be a good thing. Excited about C++ again, Christopher