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

From: Vaclav Vesely (vaclav.vesely_at_[hidden])
Date: 2006-10-10 04:11:53

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