Question

May I know is there any way to determine parent class from boost::any?

#include <iostream>
#include <boost/any.hpp>

class a {
public:
    virtual ~a() {}
};

class b : public a {
};

bool is_class_a(const boost::any& any)
{
    return boost::any_cast<a>(&any) != 0;
}

bool is_class_a_v2(const boost::any& any)
{
    try
    {
        boost::any_cast<a>(any);
        return true;
    }
    catch(const boost::bad_any_cast &)
    {
        return false;
    }
}

int main()
{
    std::cout<< is_class_a(b())<< std::endl;    // return 0. but i wish to return 1.
    std::cout<< is_class_a(a())<< std::endl;    // return 1.

    std::cout<< is_class_a_v2(b())<< std::endl; // return 0. but i wish to return 1.
    std::cout<< is_class_a_v2(a())<< std::endl; // return 1.
}

Answer 1

boost::any was designed so that it holds strongly informational objects for which identity is not significant. If you want to work with polymorphic types then you could use pointers to base class or boost::shared_ptr with base class instead of boost::any.