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

Vaclav Vesely wrote:

Fernando Cacciola wrote:

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Vaclav Vesely wrote:

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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.

Perhaps you can use Boost.PtrContainer: typedef boost::ptr_vector< boost::nullable<Base> > OptionalContainer; ? -Thorsten