Hi!what do you mean by parent? boost::any does not derive from any other class. Just a note, using that version of cast:
boost::any_cast<a*>(&any);
or
boost::any_cast<a const*>(&any);
will not throw, but return a null pointer if any does not contain the expected type. Consider using boost::variant, which supports visitor-pattern for dispatching.
Best Regards,
Ovanes
On Mon, Nov 23, 2009 at 5:18 PM, Yan Cheng Cheok
<yccheok@yahoo.com> wrote:
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.
}
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