Re: [boost] optional: Extending optional to hold derived values

10 Oct 2006

      Fernando Cacciola wrote:
...
Vaclav Vesely wrote:
...
I would like to do somethink like this:
class Base {...}
    class Derived: public Base {...}
optional<Base> x = Derived();
    y->call_virtual_functions()
It looks a lot like Boost.Any.
Have you looked at it?
boost::any doesn't support derived classes as well. For example:

any x = Derived();
any_cast<Base>(x).virtual_function(); // throws bad_any_cast

And moreover boost::any is too general. I want to store only values of Base 
and its derived classes.

Regards,
Vaclav